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Sample records for fracture surface analysis

  1. 3-D description of fracture surfaces and stress-sensitivity analysis for naturally fractured reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, S.Q.; Jioa, D.; Meng, Y.F.; Fan, Y.

    1997-08-01

    Three kinds of reservoir cores (limestone, sandstone, and shale with natural fractures) were used to study the effect of morphology of fracture surfaces on stress sensitivity. The cores, obtained from the reservoirs with depths of 2170 to 2300 m, have fractures which are mated on a large scale, but unmated on a fine scale. A specially designed photoelectric scanner with a computer was used to describe the topography of the fracture surfaces. Then, theoretical analysis of the fracture closure was carried out based on the fracture topography generated. The scanning results show that the asperity has almost normal distributions for all three types of samples. For the tested samples, the fracture closure predicted by the elastic-contact theory is different from the laboratory measurements because plastic deformation of the aspirates plays an important role under the testing range of normal stresses. In this work, the traditionally used elastic-contact theory has been modified to better predict the stress sensitivity of reservoir fractures. Analysis shows that the standard deviation of the probability density function of asperity distribution has a great effect on the fracture closure rate.

  2. Anisotropic characterization of rock fracture surfaces subjected to profile analysis

    International Nuclear Information System (INIS)

    Zhou, H.W.; Xie, H.

    2004-01-01

    The mechanical parameters of a rock fracture are dependent on its surface roughness anisotropy. In this Letter, we show how quantitatively describe the anisotropy of a rock fracture surface. A parameter, referred to as the index for the accumulation power spectral density psd*, is proposed to characterize the anisotropy of a rock fracture surface. Variation of psd*, with orientation angle θ of sampling, is also discussed

  3. QAPP for Hydraulic Fracturing (HF) Surface Spills Data Analysis

    Science.gov (United States)

    This QAPP provides information concerning the analysis of spills associated with hydraulic fracturing. This project is relevant to both the chemical mixing and flowback and produced water stages of the HF water cycle as found in the HF Study Plan.

  4. Evaluation of tensile strength and fracture toughness of yttria-stabilized zirconia polycrystals with fracture surface analysis

    International Nuclear Information System (INIS)

    Oishi, Manabu; Matsuda, Yukihisa; Noguchi, Kenichi; Masaki, Takaki

    1995-01-01

    The tensile strength of yttria-stabilized tetragonal zirconia polycrystals (Y-TZPs) was measured and the fracture surfaces were analyzed with the scanning electron microscope and X-ray microanalyzer. The fracture origins of the pressureless-sintered samples were voids or inclusions such as Al 2 O 3 , Al 2 O 3 with SiO 2 , and cubic-ZrO 2 , while the fracture origins of the hot isostatically pressed samples were inclusions; no voids were detected at fracture origins. The higher strengths of the hot isostatically pressed samples versus those of the pressureless-sintered samples were consistent with the change in fracture origins. The fracture toughness of the samples calculate from the tensile strength and analysis of the fracture origins was 3.4 to 3.7 MPa ·√m. These values are lower than those measured with the SEPB method. These discrepancies might be caused by the difference in the state of the fracture origin and its neighborhood, such as the size of the fracture origin and interaction between two surfaces in the precrack

  5. Statistical analysis of surface lineaments and fractures for characterizing naturally fractured reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Genliang; George, S.A.; Lindsey, R.P.

    1997-08-01

    Thirty-six sets of surface lineaments and fractures mapped from satellite images and/or aerial photos from parts of the Mid-continent and Colorado Plateau regions were collected, digitized, and statistically analyzed in order to obtain the probability distribution functions of natural fractures for characterizing naturally fractured reservoirs. The orientations and lengths of the surface linear features were calculated using the digitized coordinates of the two end points of each individual linear feature. The spacing data of the surface linear features within an individual set were, obtained using a new analytical sampling technique. Statistical analyses were then performed to find the best-fit probability distribution functions for the orientation, length, and spacing of each data set. Twenty-five hypothesized probability distribution functions were used to fit each data set. A chi-square goodness-of-fit test was used to rank the significance of each fit. A distribution which provides the lowest chi-square goodness-of-fit value was considered the best-fit distribution. The orientations of surface linear features were best-fitted by triangular, normal, or logistic distributions; the lengths were best-fitted by PearsonVI, PearsonV, lognormal2, or extreme-value distributions; and the spacing data were best-fitted by lognormal2, PearsonVI, or lognormal distributions. These probability functions can be used to stochastically characterize naturally fractured reservoirs.

  6. Analysis of the intergranular fracture surface by the Fourier spectrum method

    Energy Technology Data Exchange (ETDEWEB)

    Hao Yao; Tian Jifeng; Wang Zhongguang (National Lab. for Fatigue and Fracture of Materials, Inst. of Metal Research, Academia Sinica, Shen Yang (China))

    1991-11-30

    A quantitative analysis of the fracture surface of a 1045 steel was undertaken in order to relate important microstructural features to brittle intergranular fractures in the steel. It was found that the character of the profile was not random but periodic. There is a direct correspondence between the Fourier spectrum of the profile and the microstructure features. Utilization of secondary-electron line scanning facilitated the analysis of the fracture surface in this case. The results of the analysis from both the profile and the scanning line showed that the first autocorrelation length is related to the average grain size and that the total power corresponds to the impact energy of the fracture. (orig.).

  7. Analysis of fracture surface of CFRP material by three-dimensional reconstruction methods

    International Nuclear Information System (INIS)

    Lobo, Raquel M.; Andrade, Arnaldo H.P.

    2009-01-01

    Fracture surfaces of CFRP (carbon Fiber Reinforced Polymer) materials, used in the nuclear fuel cycle, presents an elevated roughness, mainly due to the fracture mode known as pulling out, that displays pieces of carbon fibers after debonding between fiber and matrix. The fractographic analysis, by bi-dimensional images is deficient for not considering the so important vertical resolution as much as the horizontal resolution. In this case, the knowledge of this heights distribution that occurs during the breaking, can lead to the calculation of the involved energies in the process that would allows a better agreement on the fracture mechanisms of the composite material. An important solution for the material characterization, whose surface presents a high roughness due to the variation in height, is to reconstruct three-dimensionally these fracture surfaces. In this work, the 3D reconstruction was done by two different methods: the variable focus reconstruction, through a stack of images obtained by optical microscopy (OM) and the parallax reconstruction, carried through with images acquired by scanning electron microscopy (SEM). The results of both methods present an elevation map of the reconstructed image that determine the height of the surface pixel by pixel,. The results obtained by the methods of reconstruction for the CFRP surfaces, have been compared with others materials such as aluminum and copper that present a ductile type fracture surface, with lower roughness. (author)

  8. Analysis of BTEX groundwater concentrations from surface spills associated with hydraulic fracturing operations.

    Science.gov (United States)

    Gross, Sherilyn A; Avens, Heather J; Banducci, Amber M; Sahmel, Jennifer; Panko, Julie M; Tvermoes, Brooke E

    2013-04-01

    Concerns have arisen among the public regarding the potentialfor drinking-water contamination from the migration of methane gas and hazardous chemicals associated with hydraulic fracturing and horizontal drilling. However, little attention has been paid to the potentialfor groundwater contamination resulting from surface spills from storage and production facilities at active well sites. We performed a search for publically available data regarding groundwater contamination from spills at ULS. drilling sites. The Colorado Oil and Gas Conservation Commission (COGCC) database was selected for further analysis because it was the most detailed. The majority ofspills were in Weld County, Colorado, which has the highest density of wells that used hydraulic fracturing for completion, many producing both methane gas and crude oil. We analyzed publically available data reported by operators to the COGCC regarding surface spills that impacted groundwater From July 2010 to July 2011, we noted 77 reported surface spills impacting the groundwater in Weld County, which resulted in surface spills associated with less than 0.5% of the active wells. The reported data included groundwater samples that were analyzed for benzene, toluene, ethylbenzene, andxylene (BTEX) components of crude oil. For groundwater samples taken both within the spill excavation area and on the first reported date of sampling, the BTEX measurements exceeded National Drinking Water maximum contaminant levels (MCLs) in 90, 30, 12, and 8% of the samples, respectively. However, actions taken to remediate the spills were effective at reducing BJTEX levels, with at least 84% of the spills reportedly achieving remediation as of May 2012. Our analysis demonstrates that surface spills are an important route of potential groundwater contamination from hydraulic fracturing activities and should be a focus of programs to protect groundwater While benzene can occur naturally in groundwater sources, spills and migration

  9. Fracture surfaces of granular pastes.

    Science.gov (United States)

    Mohamed Abdelhaye, Y O; Chaouche, M; Van Damme, H

    2013-11-01

    Granular pastes are dense dispersions of non-colloidal grains in a simple or a complex fluid. Typical examples are the coating, gluing or sealing mortars used in building applications. We study the cohesive rupture of thick mortar layers in a simple pulling test where the paste is initially confined between two flat surfaces. After hardening, the morphology of the fracture surfaces was investigated, using either the box counting method to analyze fracture profiles perpendicular to the mean fracture plane, or the slit-island method to analyze the islands obtained by cutting the fracture surfaces at different heights, parallel to the mean fracture plane. The fracture surfaces were shown to exhibit scaling properties over several decades. However, contrary to what has been observed in the brittle or ductile fracture of solid materials, the islands were shown to be mass fractals. This was related to the extensive plastic flow involved in the fracture process.

  10. Fracture analysis

    International Nuclear Information System (INIS)

    Ueng, Tzoushin; Towse, D.

    1991-01-01

    Fractures are not only the weak planes of a rock mass, but also the easy passages for the fluid flow. Their spacing, orientation, and aperture will affect the deformability, strength, heat transmittal, and fluid transporting properties of the rock mass. To understand the thermomechanical and hydrological behaviors of the rock surrounding the heater emplacement borehole, the location, orientation, and aperture of the fractures of the rock mass should be known. Borehole television and borescope surveys were performed to map the location, orientation, and aperture of the fractures intersecting the boreholes drilled in the Prototype Engineered Barrier System Field Tests (PEBSFT) at G-Tunnel. Core logging was also performed during drilling. However, because the core was not oriented and the depth of the fracture cannot be accurately determined, the results of the core logging were only used as reference and will not be discussed here

  11. Quantitative analysis by X-ray fractography of fatigue fractured surface under variable amplitude loading

    International Nuclear Information System (INIS)

    Akita, Koichi; Kodama, Shotaro; Misawa, Hiroshi

    1994-01-01

    X-ray fractography is a method of analysing the causes of accidental fracture of machine components or structures. Almost all of the previous research on this problem has been carried out using constant amplitude fatigue tests. However, the actual loads on components and structures are usually of variable amplitudes. In this study, X-ray fractography was applied to fatigue fractured surfaces produced by variable amplitude loading. Fatigue tests were carried out on Ni-Cr-Mo steel CT specimens under the conditions of repeated, two-step and multiple-step loading. Residual stresses were measured on the fatigue fractured surface by an X-ray diffraction method. The relationships between residual stress and stress intensity factor or crack propagation rate were studied. They were discussed in terms of the quantitative expressions under constant amplitude loading, proposed by the authors in previous papers. The main results obtained were as follows : (1) It was possible to estimate the crack propagation rate of the fatigue fractured surface under variable amplitude loading by using the relationship between residual stress and stress intensity factor under constant amplitude loading. (2) The compressive residual stress components on the fatigue fractured surface correspond with cyclic softening of the material rather than with compressive plastic deformation at the crack tip. (author)

  12. X-ray analysis on the fatigue fracture surface of stainless steels

    International Nuclear Information System (INIS)

    Yoshioka, Yasuo; Guimard, B.

    1986-01-01

    Several X-ray diffraction parameters were observed on the fatigue fracture surface and its vicinity of both of SUS420J1 martensitic and SUS304 austenitic stainless steels and we discussed the relation between the stress intensity factor and these parameters. Monotonic plastic zone depth determined by the measurement of residual stress distribution proportionals to the squre of the maximum stress intensity factor as well as the case of ferritic steel. However, it is very difficult to find the relation between the stress intensity factor and residual stress or half value breadth of X-ray diffraction profile in the fracture surface for both materials. On the other hand, the amount of martensite induced by the transformation during fatigue process in SUS304 is related to the maximum stress intensity factor in the fracture surface regardless the stress ratio R. (author)

  13. Fracture surface analysis on nano-SiO{sub 2}/epoxy composite

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Rongguo [Institute of Fundamental Mechanics and Material Engineering, Xiangtan University, Hunan 411105 (China); Key Laboratory of Low Dimensional Materials and Application Technology, Xiangtan University, Ministry of Education, Hunan 411105 (China)], E-mail: zhaorongguo@xtu.edu.cn; Luo Wenbo [Institute of Fundamental Mechanics and Material Engineering, Xiangtan University, Hunan 411105 (China); Key Laboratory of Low Dimensional Materials and Application Technology, Xiangtan University, Ministry of Education, Hunan 411105 (China)

    2008-06-15

    Fracture surface morphologies of nano-SiO{sub 2}/epoxy composite with different weight percentage of SiO{sub 2} are investigated using scanning electron microscopy. Two types of curing agent, dimethylbenzanthracene (DMBA) and methyltetrahydrophthalic anhydride (MeTHPA), are individually used for preparing the composites. It is found that the fracture surface morphology of the composite cured by DMBA shows as radial striations, which suggests a rapid brittle fracture mode, while the fracture surface morphology of the composite cured by MeTHPA shows as regularly spaced 'rib' markings, which indicates a stick-slip motion during the fracture process. Furthermore, the uniaxial tensile behavior under constant loading rate and ambient temperature are investigated. It is shown that the elastic modulus of the composite cured by DMBA firstly increases, and then decreases with the mass fraction of nano-SiO{sub 2} particles, but the elongation of the composite cured by MeTHPA is reversed with increasing fraction of nano-SiO{sub 2} particles. For nano-SiO{sub 2}/epoxy composite cured with MeTHPA that possesses a suitable fraction of nano-SiO{sub 2}, an excellent synthetic mechanical property on elastic modulus and elongation is obtained.

  14. The influences of mesh subdivision on nonlinear fracture analysis for surface cracked structures

    International Nuclear Information System (INIS)

    Shimakawa, T.

    1991-01-01

    The leak-before-break (LBB) concept can be expected to be applied not only to safety assessment, but also to the rationalization of nuclear power plants. The development of a method to evaluate fracture characteristics is required to establish this concept. The finite element method (FEM) is one of the most useful tools for this evaluation. However, the influence of various factors on the solution is not well understood and the reliability has not been fully verified. In this study, elastic-plastic 3D analyses are performed for two kinds of surface cracked structure, and the influence of mesh design is discussed. The first problem is surface crack growth in a carbon steel plate subjected to tension loading. A crack extension analysis is performed under a generation phase simulation using the crack release technique. Numerical instability of the J-integral solution is observed when the number of elements in the thickness direction of the ligament is reduced to three. The influence of mesh design in the ligament on the solution is discussed. The second problem is a circumferential part-through crack in a carbon steel pipe subjected to a bending moment. Two kinds of mesh design are employed, and a comparison between two sets of results shows that the number of elements on the crack surface also affects the solution as well as the number of elements in the ligament. (author)

  15. Fracture surface analysis in composite and titanium bonding: Part 1: Titanium bonding

    Science.gov (United States)

    Sanderson, K. A.; Wightman, J. P.

    1985-01-01

    Fractured lap shear Ti 6-4 adherends bonded with polyphenyquinoxaline (PPQ) and polysulfone were analyzed. The effects of adherend pretreatment, stress level, thermal aging, anodizing voltage, and modified adhesive of Ti 6-4 adherend bonded with PPQ on lap shear strength were studied. The effect of adherend pretreatment on lap shear strength was investigated for PS samples. Results of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) used to study the surface topography and surface composition are also discussed.

  16. Automated Method for Fractographic Analysis of Shape and Size of Dimples on Fracture Surface of High-Strength Titanium Alloys

    Directory of Open Access Journals (Sweden)

    Ihor Konovalenko

    2018-03-01

    Full Text Available An automated method for analyzing the shape and size of dimples of ductile tearing formed during static and impact fracture of titanium alloys VT23 and VT23M is proposed. The method is based on the analysis of the image topology. The method contains the operations of smoothing the initial fractographic image; its convolution with a filter to identify the topological ridges; thresholding with subsequent skeletonization to identify boundaries between dimples; clustering to isolate the connected areas that represent the sought objects—dimples. For each dimple, the following quantitative characteristics were calculated: area, coefficient of roundness and visual depth in units of image intensity. The surface of ductile tearing was studied by analyzing the peculiarities of parameter distribution of the found dimples. The proposed method is applied to fractograms of fracture surfaces of titanium alloys VT23 and VT23M.

  17. Determination of the fractal dimension surface of the fracture from SEM images with assistance of the computer image quantitative analysis system

    International Nuclear Information System (INIS)

    Wawszczak, J.

    1999-01-01

    This paper presents a procedure for quantitative image analysis for determination of the fractal dimension from SEM surface images of the fracture 0H14N5CuNb steel. Investigated quenched and tempered samples of the steel after impact tests (in room and -85 o C temperatures). This method can be useful for analysing local fractal dimension of any surface parts (not oriented) of the fracture with different topography of this surface. (author)

  18. Statistics of ductile fracture surfaces: the effect of material parameters

    DEFF Research Database (Denmark)

    Ponson, Laurent; Cao, Yuanyuan; Bouchaud, Elisabeth

    2013-01-01

    distributed. The three dimensional analysis permits modeling of a three dimensional material microstructure and of the resulting three dimensional stress and deformation states that develop in the fracture process region. Material parameters characterizing void nucleation are varied and the statistics...... of the resulting fracture surfaces is investigated. All the fracture surfaces are found to be self-affine over a size range of about two orders of magnitude with a very similar roughness exponent of 0.56 ± 0.03. In contrast, the full statistics of the fracture surfaces is found to be more sensitive to the material...

  19. Physical fracture properties (fracture surfaces as information sources; crackgrowth and fracture mechanisms; exemples of cracks)

    International Nuclear Information System (INIS)

    Meny, Lucienne.

    1979-06-01

    Fracture surfaces are considered as a useful source of informations: an introduction to fractography is presented; the fracture surface may be observed through X ray microanalysis, and other physical methods such as Auger electron spectroscopy or secundary ion emission. The mechanisms of macroscopic and microscopic crackgrowth and fracture are described, in the case of unstable fracture (cleavage, ductile with shear, intergranular brittleness) and of progressive crack propagation (creep, fatigue). Exemples of cracks are presented in the last chapter [fr

  20. Analysis of stress fractures associated with lameness in Thoroughbred flat racehorses training on different track surfaces undergoing nuclear scintigraphic examination.

    Science.gov (United States)

    MacKinnon, M C; Bonder, D; Boston, R C; Ross, M W

    2015-05-01

    There is limited information regarding the impact of training track surface on the occurrence of stress fractures. To evaluate the impact of training track surface on the proportion of long bone and pelvic stress fractures associated with lameness in Thoroughbred horses in flat race training undergoing nuclear scintigraphic examination. Retrospective study. Scintigraphic examinations of Thoroughbred flat racehorses were evaluated from 2 hospitals (hospital A [Toronto Equine Hospital], 2003-2009, and hospital B [George D. Widener Hospital for Large Animals, School of Veterinary Medicine, University of Pennsylvania], 1994-2006). Horses admitted to hospital A trained at a single track, at which the main training surface changed from dirt to synthetic on 27 August 2006. Two distinct populations existed at hospital B: horses that trained on dirt (numerous trainers) and those that trained on turf (single trainer). All scintigraphic images were evaluated by a blinded reviewer. Fisher's exact test and logistic regression were used when appropriate, and significance was set at Pfractures detected in scintigraphic examinations from horses training on a synthetic surface (31.7%) in comparison to scintigraphic examinations from horses training on a dirt surface (23.0%) at an earlier point in time (P = 0.03). There was a greater proportion of hindlimb/pelvic and tibial stress fractures diagnosed in horses from the synthetic surface-trained group than from the dirt-trained group at hospital A (Pfractures diagnosed, but other factors, such as training philosophy, appear to be important. Future prospective investigations to fully elucidate the relationship between training track surface and the proportion of stress fractures and other nonfatal musculoskeletal injuries are warranted. © 2014 EVJ Ltd.

  1. Fractures on curved surfaces: A classic problem solved

    Science.gov (United States)

    Balcerak, Ernie

    2011-11-01

    Sheeting joints—large fractures parallel to a curved rock surface—are common in many locations on Earth, such as the iconic Half Dome in Yosemite National Park in California. Explaining how these fractures form has been a classic unsolved problem in geology. Martel solved the problem by reformulating the static equilibrium equations in a curvilinear reference frame. His analysis shows that compression along a curved surface can induce tension perpendicular to the surface, which can cause subsurface cracks to open. He found that the curvature of a rock surface plays a key role in the formation of fractures.

  2. The Surface and Interior Evolution of Ceres Revealed by Analysis of Fractures and Secondary Crater Chains Using Dawn Data

    Science.gov (United States)

    Scully, J. E. C.; Buczkowski, D.; King, S. D.; Castillo, J. C.; Schmedemann, N.; Raymond, C. A.; O'Brien, D. P.; Marchi, S.; Russell, C. T.; Mitri, G.; Bland, M. T.

    2016-12-01

    Dawn is the first spacecraft to visit and orbit Ceres, a dwarf planet and the largest body in the asteroid belt (radius 470 km) (Russell et al., 2016). Previously, telescopic observations and thermal evolution modeling indicated Ceres was at least partially differentiated, with a density of 2,100 kg/m3 (e.g. Drummond et al., 2014; Castillo-Rogez & McCord, 2010). Moreover, models of crater retention predicted that pervasive viscous relaxation in a water-ice-rich outer layer could erase most surface features (Bland, 2013). However, a full understanding of Ceres' surface and interior evolution remained elusive until Dawn explored Ceres. Here we present a global geologic map of Ceres' ≥1 km wide linear features, which we interpret as: 1) the surface expression of subsurface fractures, and 2) secondary crater chains formed when material ejected during impact-crater formation impacts and scours the surface. The formation and preservation of these linear features indicate Ceres' outer layer is relatively strong, and not dominated by viscous relaxation as predicted (Buczkowski et al., 2016). The fractures (called the Samhain Catenae) give us insights into the interior. Based on a fracture spacing to fractured layer thickness ratio of 1 (Bai & Pollard, 2000), the spacing of the Samhain Catenae indicates that the outer, fractured layer is 88 km thick. Moreover, consistent with geodynamic modeling (King et al., 2016), we interpret the Samhain Catenae formed because of uplift and extension induced by an upwelling region. Unlike many cerean secondary crater chains, the Junina Catenae secondary crater chains are not radial to their source impact crater(s). On account of Ceres' fast rotation (period of 9 hours) and relatively small radius, modeling indicates that the Junina Catenae originated from the Urvara/Yalode impact craters, which are located in a different hemisphere. Our results show Ceres has different surface and interior characteristics than predicted, and underwent

  3. Elastic-plastic fracture mechanics analysis of a pressure vessel with an axial outer surface flaw

    International Nuclear Information System (INIS)

    Aurich, D.

    1988-04-01

    Elastic-plastic finite element analyses of a test vessel (steel 1.6310=20 MnMoNi 55) with a semi-elliptical axial outer surface crack have been performed. The variations of J and CTOD along the crack front and the stresse state in the vicinity of the crack are presented. The applicability of approaches to determine J is examined. The FE results are compared with the experimental data. The results are analyzed with respect to the validity of J-controlled crack growth. It will be shown that the local ductile crack growth and, especially, the 'canoe effect' for a semi-elliptical crack can only be described correctly if local J R -curves are used which account for the varying triaxiality of the stress state along the crack front. (orig./HP) [de

  4. Prediction of Ductile Fracture Surface Roughness Scaling

    DEFF Research Database (Denmark)

    Needleman, Alan; Tvergaard, Viggo; Bouchaud, Elisabeth

    2012-01-01

    . Ductile crack growth in a thin strip under mode I, overall plane strain, small scale yielding conditions is analyzed. Although overall plane strain loading conditions are prescribed, full 3D analyses are carried out to permit modeling of the three dimensional material microstructure and of the resulting......Experimental observations have shown that the roughness of fracture surfaces exhibit certain characteristic scaling properties. Here, calculations are carried out to explore the extent to which a ductile damage/fracture constitutive relation can be used to model fracture surface roughness scaling...... three dimensional stress and deformation states that develop in the fracture process region. An elastic-viscoplastic constitutive relation for a progressively cavitating plastic solid is used to model the material. Two populations of second phase particles are represented: large inclusions with low...

  5. Water infiltration into exposed fractured rock surfaces

    International Nuclear Information System (INIS)

    Rasmussen, T.C.; Evans, D.D.

    1993-01-01

    Fractured rock media are present at many existing and potential waste disposal sites, yet characterization data and physical relationships are not well developed for such media. This study focused on water infiltration characteristics of an exposed fractured rock as an approach for defining the upper boundary condition for unsaturated-zone water percolation and contaminant transport modeling. Two adjacent watersheds of 0.24 and 1.73 ha with slopes up to 45% were instrumented for measuring rainfall and runoff. Fracture density was measured from readily observable fracture traces on the surface. Three methods were employed to evaluate the rainfall-runoff relationship. The first method used the annual totals and indicated that only 22.5% of rainfall occurred as runoff for the 1990-1991 water year, which demonstrates a high water intake rate by the exposed fracture system. The second method employed total rainfall and runoff for individual storms in conjunction with the commonly used USDA Soil Conservation Service curve number method developed for wide ranges of soils and vegetation. Curve numbers between 75 and 85 were observed for summer and winter storms with dry antecedent runoff conditions, while values exceeded 90 for wet conditions. The third method used a mass-balance approach for four major storms, which indicated that water intake rates ranged from 2.0 to 7.3 mm h -1 , yielding fracture intake velocities ranging from 122 to 293 m h -1 . The three analyses show the complexity of the infiltration process for fractured rock. However, they contribute to a better understanding of the upper boundary condition for predicting contaminant transport through an unsaturated fractured rock medium. 17 refs., 4 figs., 1 tab

  6. Failure analysis of fractured dental zirconia implants.

    Science.gov (United States)

    Gahlert, M; Burtscher, D; Grunert, I; Kniha, H; Steinhauser, E

    2012-03-01

    The purpose of the present study was the macroscopic and microscopic failure analysis of fractured zirconia dental implants. Thirteen fractured one-piece zirconia implants (Z-Look3) out of 170 inserted implants with an average in situ period of 36.75±5.34 months (range from 20 to 56 months, median 38 months) were prepared for macroscopic and microscopic (scanning electron microscopy [SEM]) failure analysis. These 170 implants were inserted in 79 patients. The patient histories were compared with fracture incidences to identify the reasons for the failure of the implants. Twelve of these fractured implants had a diameter of 3.25 mm and one implant had a diameter of 4 mm. All fractured implants were located in the anterior side of the maxilla and mandibula. The patient with the fracture of the 4 mm diameter implant was adversely affected by strong bruxism. By failure analysis (SEM), it could be demonstrated that in all cases, mechanical overloading caused the fracture of the implants. Inhomogeneities and internal defects of the ceramic material could be excluded, but notches and scratches due to sandblasting of the surface led to local stress concentrations that led to the mentioned mechanical overloading by bending loads. The present study identified a fracture rate of nearly 10% within a follow-up period of 36.75 months after prosthetic loading. Ninety-two per cent of the fractured implants were so-called diameter reduced implants (diameter 3.25 mm). These diameter reduced implants cannot be recommended for further clinical use. Improvement of the ceramic material and modification of the implant geometry has to be carried out to reduce the failure rate of small-sized ceramic implants. Nevertheless, due to the lack of appropriate laboratory testing, only clinical studies will demonstrate clearly whether and how far the failure rate can be reduced. © 2011 John Wiley & Sons A/S.

  7. Ductile fracture surface morphology of amorphous metallic alloys

    NARCIS (Netherlands)

    Miskuf, J; Csach, K; Ocelik, [No Value; Bengus, VZ; Tabachnikova, ED; Duhaj, P; Ocelik, Vaclav

    1999-01-01

    Fracture surfaces of ductile failure of two types bulk amorphous metallic alloys were studied using quantitative and qualitative fractographic analysis. The observed fractographic behaviour of ductile failure in comparison with the ductile failure of amorphous alloy ribbons shows signs of the same

  8. Assessing Impact Direction in 3-point Bending of Human Femora: Incomplete Butterfly Fractures and Fracture Surfaces,.

    Science.gov (United States)

    Isa, Mariyam I; Fenton, Todd W; Deland, Trevor; Haut, Roger C

    2018-01-01

    Current literature associates bending failure with butterfly fracture, in which fracture initiates transversely at the tensile surface of a bent bone and branches as it propagates toward the impact surface. The orientation of the resulting wedge fragment is often considered diagnostic of impact direction. However, experimental studies indicate bending does not always produce complete butterfly fractures or produces wedge fragments variably in tension or compression, precluding their use in interpreting directionality. This study reports results of experimental 3-point bending tests on thirteen unembalmed human femora. Complete fracture patterns varied following bending failure, but incomplete fractures and fracture surface characteristics were observed in all impacted specimens. A flat, billowy fracture surface was observed in tension, while jagged, angular peaks were observed in compression. Impact direction was accurately reconstructed using incomplete tension wedge butterfly fractures and tension and compression fracture surface criteria in all thirteen specimens. © 2017 American Academy of Forensic Sciences.

  9. Scaling exponents for fracture surfaces in opal glass

    International Nuclear Information System (INIS)

    Chavez-Guerrero, L.; Garza, F.J.; Hinojosa, M.

    2010-01-01

    We have investigated the scaling properties of fracture surfaces in opal glass. Specimens with two different opacifying particle sizes (1 μm and 0.4 μm) were broken by three-point bending test and the resulting fracture surfaces were analyzed using Atomic Force Microscopy. The analysis of the self-affine behavior was performed using the Variable Bandwidth and Height-Height Correlation Methods, and both the roughness exponent, ζ, and the correlation length, ξ, were determined. It was found that the roughness exponent obtained in both samples is ζ ∼ 0.8; whereas the correlation length in both fractures is of the order of the particle size, demonstrating the dependence of this self-affine parameter on the microstructure of opal glass.

  10. Scaling exponents for fracture surfaces in opal glass

    Energy Technology Data Exchange (ETDEWEB)

    Chavez-Guerrero, L., E-mail: guerreroleo@hotmail.com [Facultad de Ingenieria Mecanica y Electrica. Cd. Universitaria s/n, C.P. 66450, Universidad Autonoma de Nuevo Leon, Nuevo Leon (Mexico); Center of Innovation, Research and Development on Engineering and Technology, Universidad Autonoma de Nuevo Leon Monterrey, C.P. 66600, Apodaca, Nuevo Leon (Mexico); Garza, F.J., E-mail: fjgarza@gama.fime.uanl.mx [Facultad de Ciencias Quimicas, Cd. Universitaria s/n, C.P. 66450, Universidad Autonoma de Nuevo Leon, Nuevo Leon (Mexico); Hinojosa, M., E-mail: hinojosa@gama.fime.uanl.mx [Facultad de Ingenieria Mecanica y Electrica. Cd. Universitaria s/n, C.P. 66450, Universidad Autonoma de Nuevo Leon, Nuevo Leon (Mexico); Center of Innovation, Research and Development on Engineering and Technology, Universidad Autonoma de Nuevo Leon Monterrey, C.P. 66600, Apodaca, Nuevo Leon (Mexico)

    2010-09-25

    We have investigated the scaling properties of fracture surfaces in opal glass. Specimens with two different opacifying particle sizes (1 {mu}m and 0.4 {mu}m) were broken by three-point bending test and the resulting fracture surfaces were analyzed using Atomic Force Microscopy. The analysis of the self-affine behavior was performed using the Variable Bandwidth and Height-Height Correlation Methods, and both the roughness exponent, {zeta}, and the correlation length, {xi}, were determined. It was found that the roughness exponent obtained in both samples is {zeta} {approx} 0.8; whereas the correlation length in both fractures is of the order of the particle size, demonstrating the dependence of this self-affine parameter on the microstructure of opal glass.

  11. Analysis of the structural parameters that influence gas production from the Devonian shale. Annual progress report, 1979-1980. Volume II. Data repository and reports published during fiscal year 1979-1980: regional structure, surface structure, surface fractures, hydrology

    Energy Technology Data Exchange (ETDEWEB)

    Negus-De Wys, J.; Dixon, J. M.; Evans, M. A.; Lee, K. D.; Ruotsala, J. E.; Wilson, T. H.; Williams, R. T.

    1980-10-01

    This volume comprises appendices giving regional structure data, surface structure data, surface fracture data, and hydrology data. The fracture data covers oriented Devonian shale cores from West Virginia, Ohio, Virginia, Pennsylvania, and Kentucky. The subsurface structure of the Eastern Kentucky gas field is also covered. (DLC)

  12. Effect of reference loads on fracture mechanics analysis of surface cracked pipe based on reference stress method

    International Nuclear Information System (INIS)

    Shim, Do Jun; Son, Beom Goo; Kim, Young Jin; Kim, Yun Jae

    2004-01-01

    To investigate relevance of the definition of the reference stress to estimate J and C * for surface crack problems, this paper compares FE J and C * results for surface cracked pipes with those estimated according to the reference stress approach using various definitions of the reference stress. Pipes with part circumferential inner surface crack and finite internal axial crack are considered, subject to internal pressure and global bending. The crack depth and aspect ratio are systematically varied. The reference stress is defined in four different ways using (I) the local limit load, (II) the global limit load, (III) the global limit load determined from the FE limit analysis, and (IV) the optimised reference load. It is found that the reference stress based on the local limit load gives overall excessively conservative estimates of J and C * . Use of the global limit load clearly reduces the conservatism, compared to that of the local limit load, although it can provide sometimes non-conservative estimates of J and C * . The use of the FE global limit load gives overall non-conservative estimates of J and C * . The reference stress based on the optimised reference load gives overall accurate estimates of J and C * , compared to other definitions of the reference stress. Based on the present finding, general guidance on the choice of the reference stress for surface crack problems is given

  13. Elastic-plastic fracture mechanics analysis of a pressure vessel with an axial outer surface flaw. Pt. 2

    International Nuclear Information System (INIS)

    Brocks, W.; Kuenecke, G.

    1989-06-01

    Continuing preceding investigations, a further elastic-plastic finite element analysis of a test vessel with a semi-elliptical axial outer surface crack has been performed. The variations of J and CTOD along the crack front and the stress state in the vicinity of the crack are presented. The applicability of analytical approaches to determine J is examined. The FE results are used to analyze the experimental data with respect to the validity of J-controlled crack growth. Local J R -curves of the surface flaw are compared with J R -curves of various specimens of different geometries. Again, it became evident that the local ductile crack growth and, especially, the developing 'canoe shape' of the surface crack cannot be described by a single resistance curve which is assumed to be a material property. A method described in a previous report to predict the ductile crack growth by using local J R -curves which depend on the triaxiality of the stress state did not result in a satisfactory outcome, in the present case. The presumed reasons will be discussed. (orig.) [de

  14. A NEW HIGH RESOLUTION OPTICAL METHOD FOR OBTAINING THE TOPOGRAPHY OF FRACTURE SURFACES IN ROCKS

    Directory of Open Access Journals (Sweden)

    Steven Ogilvie

    2011-05-01

    Full Text Available Surface roughness plays a major role in the movement of fluids through fracture systems. Fracture surface profiling is necessary to tune the properties of numerical fractures required in fluid flow modelling to those of real rock fractures. This is achieved using a variety of (i mechanical and (ii optical techniques. Stylus profilometry is a popularly used mechanical method and can measure surface heights with high precision, but only gives a good horizontal resolution in one direction on the fracture plane. This method is also expensive and simultaneous coverage of the surface is not possible. Here, we describe the development of an optical method which images cast copies of rough rock fractures using in-house developed hardware and image analysis software (OptiProf™ that incorporates image improvement and noise suppression features. This technique images at high resolutions, 15-200 μm for imaged areas of 10 × 7.5 mm and 100 × 133 mm, respectively and a similar vertical resolution (15 μm for a maximum topography of 4 mm. It uses in-house developed hardware and image analysis (OptiProf™ software and is cheap and non-destructive, providing continuous coverage of the fracture surface. The fracture models are covered with dye and fluid thicknesses above the rough surfaces converted into topographies using the Lambert-Beer Law. The dye is calibrated using 2 devices with accurately known thickness; (i a polycarbonate tile with wells of different depths and (ii a wedge-shaped vial made from silica glass. The data from each of the two surfaces can be combined to provide an aperture map of the fracture for the scenario where the surfaces touch at a single point or any greater mean aperture. The topography and aperture maps are used to provide data for the generation of synthetic fractures, tuned to the original fracture and used in numerical flow modelling.

  15. SEM/XPS analysis of fractured adhesively bonded graphite fibre surface resin-rich/graphite fibre composites

    Science.gov (United States)

    Devilbiss, T. A.; Wightman, J. P.; Progar, D. J.

    1988-01-01

    Samples of graphite fiber-reinforced polyimide were fabricated allowing the resin to accumulate at the composite surface. These surface resin-rich composites were then bonded together and tested for lap shear strength both before and after thermal aging. Lap shear strength did not appear to show a significant improvement over that previously recorded for resin-poor samples and was shown to decrease with increasing aging time and temperature.

  16. Fracture behavior of short circumferentially surface-cracked pipe

    International Nuclear Information System (INIS)

    Krishnaswamy, P.; Scott, P.; Mohan, R.

    1995-11-01

    This topical report summarizes the work performed for the Nuclear Regulatory Comniission's (NRC) research program entitled ''Short Cracks in Piping and Piping Welds'' that specifically focuses on pipes with short, circumferential surface cracks. The following details are provided in this report: (i) material property deteminations, (ii) pipe fracture experiments, (iii) development, modification and validation of fracture analysis methods, and (iv) impact of this work on the ASME Section XI Flaw Evaluation Procedures. The material properties developed and used in the analysis of the experiments are included in this report and have been implemented into the NRC's PIFRAC database. Six full-scale pipe experiments were conducted during this program. The analyses methods reported here fall into three categories (i) limit-load approaches, (ii) design criteria, and (iii) elastic-plastic fracture methods. These methods were evaluated by comparing the analytical predictions with experimental data. The results, using 44 pipe experiments from this and other programs, showed that the SC.TNP1 and DPZP analyses were the most accurate in predicting maximum load. New Z-factors were developed using these methods. These are being considered for updating the ASME Section XI criteria

  17. Model of T-Type Fracture in Coal Fracturing and Analysis of Influence Factors of Fracture Morphology

    Directory of Open Access Journals (Sweden)

    Yuwei Li

    2018-05-01

    Full Text Available Special T-type fractures can be formed when coal is hydraulically fractured and there is currently no relevant theoretical model to calculate and describe them. This paper first establishes the height calculation model of vertical fractures in multi-layered formations and deduces the stress intensity factor (SIF at the upper and lower sides of the fracture in the process of vertical fracture extension. Combined with the fracture tip stress analysis method of fracture mechanics theory, the horizontal bedding is taken into account for tensile and shear failure, and the critical mechanical conditions for the formation of horizontal fracture in coal are obtained. Finally, the model of T-type fracture in coal fracturing is established, and it is verified by fracturing simulation experiments. The model calculation result shows that the increase of vertical fracture height facilitates the increase of horizontal fracture length. The fracture toughness of coal has a significant influence on the length of horizontal fracture and there is a threshold. When the fracture toughness is less than the threshold, the length of horizontal fracture remains unchanged, otherwise, the length of horizontal fracture increases rapidly with the increase of fracture toughness. When the shear strength of the interface between the coalbed and the interlayer increases, the length of the horizontal fracture of the T-type fracture rapidly decreases.

  18. Correlation analysis of fracture arrangement in space

    Science.gov (United States)

    Marrett, Randall; Gale, Julia F. W.; Gómez, Leonel A.; Laubach, Stephen E.

    2018-03-01

    We present new techniques that overcome limitations of standard approaches to documenting spatial arrangement. The new techniques directly quantify spatial arrangement by normalizing to expected values for randomly arranged fractures. The techniques differ in terms of computational intensity, robustness of results, ability to detect anti-correlation, and use of fracture size data. Variation of spatial arrangement across a broad range of length scales facilitates distinguishing clustered and periodic arrangements-opposite forms of organization-from random arrangements. Moreover, self-organized arrangements can be distinguished from arrangements due to extrinsic organization. Traditional techniques for analysis of fracture spacing are hamstrung because they account neither for the sequence of fracture spacings nor for possible coordination between fracture size and position, attributes accounted for by our methods. All of the new techniques reveal fractal clustering in a test case of veins, or cement-filled opening-mode fractures, in Pennsylvanian Marble Falls Limestone. The observed arrangement is readily distinguishable from random and periodic arrangements. Comparison of results that account for fracture size with results that ignore fracture size demonstrates that spatial arrangement is dominated by the sequence of fracture spacings, rather than coordination of fracture size with position. Fracture size and position are not completely independent in this example, however, because large fractures are more clustered than small fractures. Both spatial and size organization of veins here probably emerged from fracture interaction during growth. The new approaches described here, along with freely available software to implement the techniques, can be applied with effect to a wide range of structures, or indeed many other phenomena such as drilling response, where spatial heterogeneity is an issue.

  19. Dynamic characterisation of the specific surface area for fracture networks

    Science.gov (United States)

    Cvetkovic, V.

    2017-12-01

    One important application of chemical transport is geological disposal of high-level nuclear waste for which crystalline rock is a prime candidate for instance in Scandinavia. Interconnected heterogeneous fractures of sparsely fractured rock such as granite, act as conduits for transport of dissolved tracers. Fluid flow is known to be highly channelized in such rocks. Channels imply narrow flow paths, adjacent to essentially stagnant water in the fracture and/or the rock matrix. Tracers are transported along channelised flow paths and retained by minerals and/or stagnant water, depending on their sorption properties; this mechanism is critical for rocks to act as a barrier and ultimately provide safety for a geological repository. The sorbing tracers are retained by diffusion and sorption on mineral surfaces, whereas non-sorbing tracers can be retained only by diffusion into stagnant water of fractures. The retention and transport properties of a sparsely fractured rock will primarily depend on the specific surface area (SSA) of the fracture network which is determined by the heterogeneous structure and flow. The main challenge when characterising SSA on the field-scale is its dependence on the flow dynamics. We first define SSA as a physical quantity and clarify its importance for chemical transport. A methodology for dynamic characterisation of SSA in fracture networks is proposed that relies on three sets of data: i) Flow rate data as obtained by a flow logging procedure; ii) transmissivity data as obtained by pumping tests; iii) fracture network data as obtained from outcrop and geophysical observations. The proposed methodology utilises these data directly as well as indirectly through flow and particle tracking simulations in three-dimensional discrete fracture networks. The methodology is exemplified using specific data from the Swedish site Laxemar. The potential impact of uncertainties is of particular significance and is illustrated for radionuclide

  20. Effects of fracture surface roughness and shear displacement on geometrical and hydraulic properties of three-dimensional crossed rock fracture models

    Science.gov (United States)

    Huang, Na; Liu, Richeng; Jiang, Yujing; Li, Bo; Yu, Liyuan

    2018-03-01

    While shear-flow behavior through fractured media has been so far studied at single fracture scale, a numerical analysis of the shear effect on the hydraulic response of 3D crossed fracture model is presented. The analysis was based on a series of crossed fracture models, in which the effects of fracture surface roughness and shear displacement were considered. The rough fracture surfaces were generated using the modified successive random additions (SRA) algorithm. The shear displacement was applied on one fracture, and at the same time another fracture shifted along with the upper and lower surfaces of the sheared fracture. The simulation results reveal the development and variation of preferential flow paths through the model during the shear, accompanied by the change of the flow rate ratios between two flow planes at the outlet boundary. The average contact area accounts for approximately 5-27% of the fracture planes during shear, but the actual calculated flow area is about 38-55% of the fracture planes, which is much smaller than the noncontact area. The equivalent permeability will either increase or decrease as shear displacement increases from 0 to 4 mm, depending on the aperture distribution of intersection part between two fractures. When the shear displacement continuously increases by up to 20 mm, the equivalent permeability increases sharply first, and then keeps increasing with a lower gradient. The equivalent permeability of rough fractured model is about 26-80% of that calculated from the parallel plate model, and the equivalent permeability in the direction perpendicular to shear direction is approximately 1.31-3.67 times larger than that in the direction parallel to shear direction. These results can provide a fundamental understanding of fluid flow through crossed fracture model under shear.

  1. Linking advanced fracture models to structural analysis

    Energy Technology Data Exchange (ETDEWEB)

    Chiesa, Matteo

    2001-07-01

    Shell structures with defects occur in many situations. The defects are usually introduced during the welding process necessary for joining different parts of the structure. Higher utilization of structural materials leads to a need for accurate numerical tools for reliable prediction of structural response. The direct discretization of the cracked shell structure with solid finite elements in order to perform an integrity assessment of the structure in question leads to large size problems, and makes such analysis infeasible in structural application. In this study a link between local material models and structural analysis is outlined. An ''ad hoc'' element formulation is used in order to connect complex material models to the finite element framework used for structural analysis. An improved elasto-plastic line spring finite element formulation, used in order to take cracks into account, is linked to shell elements which are further linked to beam elements. In this way one obtain a global model of the shell structure that also accounts for local flexibilities and fractures due to defects. An important advantage with such an approach is a direct fracture mechanics assessment e.g. via computed J-integral or CTOD. A recent development in this approach is the notion of two-parameter fracture assessment. This means that the crack tip stress tri-axiality (constraint) is employed in determining the corresponding fracture toughness, giving a much more realistic capacity of cracked structures. The present thesis is organized in six research articles and an introductory chapter that reviews important background literature related to this work. Paper I and II address the performance of shell and line spring finite elements as a cost effective tool for performing the numerical calculation needed to perform a fracture assessment. In Paper II a failure assessment, based on the testing of a constraint-corrected fracture mechanics specimen under tension, is

  2. Fracture surface energy of the Punchbowl fault, San Andreas system.

    Science.gov (United States)

    Chester, Judith S; Chester, Frederick M; Kronenberg, Andreas K

    2005-09-01

    Fracture energy is a form of latent heat required to create an earthquake rupture surface and is related to parameters governing rupture propagation and processes of slip weakening. Fracture energy has been estimated from seismological and experimental rock deformation data, yet its magnitude, mechanisms of rupture surface formation and processes leading to slip weakening are not well defined. Here we quantify structural observations of the Punchbowl fault, a large-displacement exhumed fault in the San Andreas fault system, and show that the energy required to create the fracture surface area in the fault is about 300 times greater than seismological estimates would predict for a single large earthquake. If fracture energy is attributed entirely to the production of fracture surfaces, then all of the fracture surface area in the Punchbowl fault could have been produced by earthquake displacements totalling <1 km. But this would only account for a small fraction of the total energy budget, and therefore additional processes probably contributed to slip weakening during earthquake rupture.

  3. Analysis of compressive fracture in rock using statistical techniques

    Energy Technology Data Exchange (ETDEWEB)

    Blair, S.C.

    1994-12-01

    Fracture of rock in compression is analyzed using a field-theory model, and the processes of crack coalescence and fracture formation and the effect of grain-scale heterogeneities on macroscopic behavior of rock are studied. The model is based on observations of fracture in laboratory compression tests, and incorporates assumptions developed using fracture mechanics analysis of rock fracture. The model represents grains as discrete sites, and uses superposition of continuum and crack-interaction stresses to create cracks at these sites. The sites are also used to introduce local heterogeneity. Clusters of cracked sites can be analyzed using percolation theory. Stress-strain curves for simulated uniaxial tests were analyzed by studying the location of cracked sites, and partitioning of strain energy for selected intervals. Results show that the model implicitly predicts both development of shear-type fracture surfaces and a strength-vs-size relation that are similar to those observed for real rocks. Results of a parameter-sensitivity analysis indicate that heterogeneity in the local stresses, attributed to the shape and loading of individual grains, has a first-order effect on strength, and that increasing local stress heterogeneity lowers compressive strength following an inverse power law. Peak strength decreased with increasing lattice size and decreasing mean site strength, and was independent of site-strength distribution. A model for rock fracture based on a nearest-neighbor algorithm for stress redistribution is also presented and used to simulate laboratory compression tests, with promising results.

  4. Fracture Resistance, Surface Defects and Structural Strength of Glass

    OpenAIRE

    Rodichev, Y.M.; Veer, F.A.

    2010-01-01

    This paper poses the theory that the fracture resistance of basic float glass is dependent on it physicochemical properties and the surface defects fonned under the float glass production, glass processing and handling at the service conditions compose the aggregate basis for structural glass strength assessment. The effect of loading conditions, constructional and technological factors on the engineering strength of glass can be evaluated in certain cases using fracture mechanics with inform...

  5. Petrous bone fracture: a virtual trauma analysis.

    Science.gov (United States)

    Montava, Marion; Deveze, Arnaud; Arnoux, Pierre-Jean; Bidal, Samuel; Brunet, Christian; Lavieille, Jean-Pierre

    2012-06-01

    The temporal bone shields sensorineural, nervous, and vascular structures explaining the potential severity and complications of trauma related to road and sport accidents. So far, no clear data are available on the exact mechanisms involved for fracture processes. Modelization of structures helps to answer these concerns. Our objective was to design a finite element model of the petrous bone structure to modelize temporal bone fracture propagation in a scenario of lateral impact. A finite element model of the petrous bone structure was designed based on computed tomography data. A 7-m/s lateral impact was simulated to reproduce a typical lateral trauma. Results of model analysis was based on force recorded, stress level on bone structure up to induce a solution of continuity of the bony structure. Model simulation showed that bone fractures follow the main axes of the petrous bone and occurred in a 2-step process: first, a crush, and second, a massive fissuration of the petrous bone. The lines of fracture obtained by simulation of a lateral impact converge toward the middle ear region. This longitudinal fracture is located at the mastoid-petrous pyramid junction. Using this model, it was possible to map petrous bone fractures including fracture chronology and areas of fusion of the middle ear region. This technique may represent a first step to investigate the pathophysiology of the petrous bone fractures, aiming to define prognostic criteria for patients' care.

  6. Properties of fracture surfaces of glassy polymers: chain scission versus chain pullout

    NARCIS (Netherlands)

    Fischer, H.R.

    2010-01-01

    Fresh fracture surfaces formed by tensile failure of craze in molded polystyrene (PS) bars have been compared with the molded surfaces of the same bars, using an atomic force microscope with a thermal probe and operated in local thermal analysis. The results indicate that molecular weight is much

  7. Fracture mechanics assessment of surface and sub-surface cracks in the RPV under non-symmetric PTS loading

    Energy Technology Data Exchange (ETDEWEB)

    Keim, E; Shoepper, A; Fricke, S [Siemens AG Unternehmensbereich KWU, Erlangen (Germany)

    1997-09-01

    One of the most severe loading conditions of a reactor pressure vessel (rpv) under operation is the loss of coolant accident (LOCA) condition. Cold water is injected through nozzles in the downcomer of the rpv, while the internal pressure may remain at a high level. Complex thermal hydraulic situations occur and the fluid and downcomer temperatures as well as the fluid to wall heat transfer coefficient at the inner surface are highly non-linear. Due to this non-symmetric conditions, the problem is investigated by three-dimensional non-linear finite element analyses, which allow for an accurate assessment of the postulated flaws. Transient heat transfer analyses are carried out to analyze the effect of non-symmetrical cooling of the inner surface of the pressure vessel. In a following uncoupled stress analysis the thermal shock effects for different types of defects, surface flaws and sub-surface flaws are investigated for linear elastic and elastic-plastic material behaviour. The obtained fracture parameters are calculated along the crack fronts. By a fast fracture analysis the fracture parameters at different positions along the crack front are compared to the material resistance. Safety margins are pointed out in an assessment diagram of the fracture parameters and the fracture resistance versus the transient temperature at the crack tip position. (author). 4 refs, 10 figs.

  8. The effect of loading rate on ductile fracture toughness and fracture surface roughness

    DEFF Research Database (Denmark)

    Osovski, S.; Srivastava, Akhilesh Kumar; Ponson, L.

    2015-01-01

    The variation of ductile crack growth resistance and fracture surface roughness with loading rate is modeled under mode I plane strain, small scale yielding conditions. Three-dimensional calculations are carried out using an elastic-viscoplastic constitutive relation for a progressively cavitatin...

  9. Fractal dimension of the fractured surface of materials

    International Nuclear Information System (INIS)

    Lung, C.W.; Zhang, S.Z.

    1989-05-01

    Fractal dimension of the fractured surface of materials is discussed to show that the origin of the negative correlation between D F and toughness lies in the method of fractal dimension measurement with perimeter-area relation and also in the physical mechanism of crack propagation. (author). 8 refs, 4 figs, 1 tab

  10. Fracture Resistance, Surface Defects and Structural Strength of Glass

    NARCIS (Netherlands)

    Rodichev, Y.M.; Veer, F.A.

    2010-01-01

    This paper poses the theory that the fracture resistance of basic float glass is dependent on it physicochemical properties and the surface defects fonned under the float glass production, glass processing and handling at the service conditions compose the aggregate basis for structural glass

  11. Probabilistic fracture mechanics of nuclear structural components. Consideration of transition from embedded crack to surface crack

    International Nuclear Information System (INIS)

    Yagawa, Genki; Yoshimura, Shinobu; Kanto, Yasuhiro

    1998-01-01

    This paper describes a probabilistic fracture mechanics (PFM) analysis of aged nuclear reactor pressure vessel (RPV) material. New interpolation formulas are first derived for both embedded elliptical surface cracks and semi-elliptical surface cracks. To investigate effects of transition from embedded crack to surface crack in PFM analyses, one of PFM round-robin problems set by JSME-RC111 committee, i.e. 'aged RPV under normal and upset operating conditions' is solved, employing the interpolation formulas. (author)

  12. 3-D Experimental Fracture Analysis at High Temperature

    Energy Technology Data Exchange (ETDEWEB)

    John H. Jackson; Albert S. Kobayashi

    2001-09-14

    T*e, which is an elastic-plastic fracture parameter based on incremental theory of plasticity, was determined numerically and experimentally. The T*e integral of a tunneling crack in 2024-T3 aluminum, three point bend specimen was obtained through a hybrid analysis of moire interferometry and 3-D elastic-plastic finite element analysis. The results were verified by the good agreement between the experimentally and numerically determined T*e on the specimen surface.

  13. Fracture toughness and fracture surface energy of sintered uranium dioxide fuel pellets

    International Nuclear Information System (INIS)

    Kutty, T.R.G.; Chandrasekharan, K.N.; Panakkal, J.P.; Ghosh, J.K.

    1987-01-01

    The paper concerns the variation of fracture toughness Ksub(ic) and fracture surface energy γsub(s) in sintered uranium dioxide pellets in the density range 9.86 to 10.41 g cm -3 , using Vickers indentation technique. A minimum of four indentations were made on each pellet sample and the average crack length of each indentation and the hardness values were determined. The overall average crack-length datra and the data on volume fraction porosity in the pellets fitted a straight line, from which Ksub(ic) and γsub(s) were calculated. The fracture parameters of nonporous polycrystalline UO 2 , calculated from the experimental data, are presented in tabular form. (U.K.)

  14. Hydraulic-fracture growth in dipping anisotropic strata as viewed through the surface deformation field

    International Nuclear Information System (INIS)

    Holzhausen, G.R.; Haase, C.S.; Stow, S.H.; Gazonas, G.

    1985-01-01

    In 1983 and 1984 Oak Rdige National Laboratory conducted a series of precision ground deformation measurements before, during, and after the generation of several large hydraulic fractures in a dipping member of the Cambrian Conasauga Shale. Each fracture was produced by the injection of approximately 500,000 L of slurry on a single day. Injection depth was 300 m. Leveling surveys were run several days before and several days after the injections. An array of eight high-precision borehole tiltmeters monitored ground deformations continuously for a period of several weeks. Analysis of the leveling and the tilt measurements revealed surface uplifts as great as 25 mm and tilts of tens of microradians during each injection. Furthermore, partial recovery (subsidence) of the ground took place during the days following an injection, accompanied by shifts in the position of maximum resultant uplift. Interpretation of the tilt measurements is consistent with stable widening and extension of hydraulic fractures with subhorizontal orientations. Comparison of the measured tilt patterns with fracture orientations established from logging of observation wells suggests that shearing parallel to the fracture planes accompanied fracture dilation. This interpretation is supported by measured tilts and ground uplifts that were as much as 100 percent greater than those expected from fracture dilation alone. Models of elastically anisotropic overburden rock do not explain the measured tilt patterns in the absence of shear stresses in the fracture planes. This work represents the first large-scale hydraulic-fracturing experiment in which the possible effects of material anisotropy and fracture-parallel shears have been measured and interpreted

  15. Hydraulic-fracture growth in dipping anisotropic strata as viewed through the surface deformation field

    International Nuclear Information System (INIS)

    Holzhausen, G.R.; Haase, C.S.; Stow, S.H.; Gazonas, G.

    1985-01-01

    In 1983 and 1984 Oak Ridge National Laboratory conducted a series of precision ground deformation measurements before, during, and after the generation of several large hydraulic fractures in a dipping member of the Cambrian Conassauga Shale. Each fracture was produced by the injection of approximately 500,000 liters of slurry on a single day. Injection depth was 300 m. Leveling surveys were run several days before and several days after the injections. An array of eight high-precision borehole tiltmeters monitored ground deformations continuously for a period of several weeks. Analysis of the leveling and the tilt measurements revealed surface uplifts as great as 25 mm and tilts of tens of microradians during each injection. Furthermore, partial recovery (subsidence) of the ground took place during the days following an injection, accompanied by shifts in the position of maximum resultant uplift. Interpretation of the tilt measurements is consistent with stable widening and extension of hydraulic fractures with subhorizontal orientations. Comparison of the measured tilt patterns with fracture orientations established from logging of observation wells suggests that shearing parallel to the fracture planes accompanied fracture dilation. This interpretation is supported by measured tilts and ground uplifts that were as much as 100 percent greater than those expected from fracture dilation alone. Models of elastically anisotropic overburden rock do not explain the measured tilt patterns in the absence of shear stresses in the fracture planes. This work represents the first large-scale hydraulic-fracturing experiment in which the possible effects of material anisotropy and fracture-parallel shears have been measured and interpreted

  16. Laser-treated stainless steel mini-screw implants: 3D surface roughness, bone-implant contact, and fracture resistance analysis.

    Science.gov (United States)

    Kang, He-Kyong; Chu, Tien-Min; Dechow, Paul; Stewart, Kelton; Kyung, Hee-Moon; Liu, Sean Shih-Yao

    2016-04-01

    This study investigated the biomechanical properties and bone-implant intersurface response of machined and laser surface-treated stainless steel (SS) mini-screw implants (MSIs). Forty-eight 1.3mm in diameter and 6mm long SS MSIs were divided into two groups. The control (machined surface) group received no surface treatment; the laser-treated group received Nd-YAG laser surface treatment. Half in each group was used for examining surface roughness (Sa and Sq), surface texture, and facture resistance. The remaining MSIs were placed in the maxilla of six skeletally mature male beagle dogs in a randomized split-mouth design. A pair with the same surface treatment was placed on the same side and immediately loaded with 200 g nickel-titanium coil springs for 8 weeks. After killing, the bone-implant contact (BIC) for each MSI was calculated using micro computed tomography. Analysis of variance model and two-sample t test were used for statistical analysis with a significance level of P titanium alloy MSIs. © The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  17. Evaluation of the conditions imposed by the fracture surface geometry on water seepage through fractured porous media

    International Nuclear Information System (INIS)

    Fuentes, Nestor O.; Faybishenko, B.

    2003-01-01

    In order to determine the geometric patterns of the fracture surfaces that imposes conditions on the fluid flow through fractured porous media, a series a fracture models have been analyzed using the RIMAPS technique and the variogram method. Results confirm that the main paths followed by the fluid channels are determined by the surface topography and remain constant during water seepage evolution. Characteristics scale lengths of both situations: fracture surface and the flow of water, are also found. There exists a relationship between the scale lengths corresponding to each situation. (author)

  18. Fracture Penis: An Analysis of 26 Cases

    Directory of Open Access Journals (Sweden)

    G.V.Soundra Pandyan

    2006-01-01

    Full Text Available The aim of this study was to review the pattern of penile fracture occurrence, its clinical presentation, diagnosis, management, and outcome at our center. A retrospective analysis of 26 patients with penile fractures treated at our hospital from January 1997 to January 2005 was carried out. We noted an incidence of 3.5 cases per year, occurring more commonly in unmarried men. Of our study group, 28 episodes of penile fractures occurred in 26 patients. Hospital presentation after trauma varied from 2 h to 21 days. Masturbation was the main initiating causative factor and penile hematoma was the most common clinical finding. Nearly 81% noticed the characteristic click prior to the fracture. Clinical diagnosis was adequate in a majority of the cases. Midshaft fractures with right-sided laterality were more frequent in this series. The tear size ranged from 0.5—2.5 cm with a mean of 1.1 cm. All cases, but one, were treated by surgical repair using absorbable sutures. Out of three cases treated conservatively, two failed to respond and had to be treated surgically. False fracture with dorsal vein tear was present in two cases. Involvement of bilateral corpora was seen in one patient. Infection was the most common early complication, while pain with deviation was the late complication. In our experience, clinical findings are adequate enough to diagnose fracture penis in a majority of cases. Surgical exploration with repair of the tear is recommended both in early and delayed presentations. There was no noticeable relationship to the time of initial presentation or with the size and site of tear to the final outcome.

  19. Fracture behavior of circumferentially surface-cracked elbows. Technical report, October 1993--March 1996

    International Nuclear Information System (INIS)

    Kilinski, T.; Mohan, R.; Rudland, D.; Fleming, M.

    1996-12-01

    This report presents the results from Task 2 of the Second International Piping Integrity Research Group (IPIRG-2) program. The focus of the Task 2 work was directed towards furthering the understanding of the fracture behavior of long-radius elbows. This was accomplished through a combined analytical and experimental program. J-estimation schemes were developed for both axial and circumferential surface cracks in elbows. Large-scale, quasi-static and dynamic, pipe-system, elbow fracture experiments under combined pressure and bending loads were performed on elbows containing an internal surface crack at the extrados. In conjunction with the elbow experiments, material property data were developed for the A106-90 carbon steel and WP304L stainless steel elbow materials investigated. A comparison of the experimental data with the maximum stress predictions using existing straight pipe fracture prediction analysis methods, and elbow fracture prediction methods developed in this program was performed. This analysis was directed at addressing the concerns regarding the validity of using analysis predictions developed for straight pipe to predict the fracture stresses of cracked elbows. Finally, a simplified fitting flaw acceptance criteria incorporating ASME B2 stress indices and straight pipe, circumferential-crack analysis was developed

  20. Fracture behavior of circumferentially surface-cracked elbows. Technical report, October 1993--March 1996

    Energy Technology Data Exchange (ETDEWEB)

    Kilinski, T.; Mohan, R.; Rudland, D.; Fleming, M. [and others

    1996-12-01

    This report presents the results from Task 2 of the Second International Piping Integrity Research Group (IPIRG-2) program. The focus of the Task 2 work was directed towards furthering the understanding of the fracture behavior of long-radius elbows. This was accomplished through a combined analytical and experimental program. J-estimation schemes were developed for both axial and circumferential surface cracks in elbows. Large-scale, quasi-static and dynamic, pipe-system, elbow fracture experiments under combined pressure and bending loads were performed on elbows containing an internal surface crack at the extrados. In conjunction with the elbow experiments, material property data were developed for the A106-90 carbon steel and WP304L stainless steel elbow materials investigated. A comparison of the experimental data with the maximum stress predictions using existing straight pipe fracture prediction analysis methods, and elbow fracture prediction methods developed in this program was performed. This analysis was directed at addressing the concerns regarding the validity of using analysis predictions developed for straight pipe to predict the fracture stresses of cracked elbows. Finally, a simplified fitting flaw acceptance criteria incorporating ASME B2 stress indices and straight pipe, circumferential-crack analysis was developed.

  1. Japanese round robin analysis for probabilistic fracture mechanics

    International Nuclear Information System (INIS)

    Yagawa, G.; Yoshimura, S.; Handa, N.

    1991-01-01

    Recently attention is focused on the probabilistic fracture mechanics, a branch of fracture mechanics with probability theory for a rational mean to assess the strength of components and structures. In particular, the probabilistic fracture mechanics is recognized as the powerful means for quantitative investigation of significance of factors and rational evaluation of life on problems involving a number of uncertainties, such as degradation of material strength, accuracy and frequency of inspection. Comparison with reference experiments are generally employed to assure the analytical accuracy. However, accuracy and reliability of analytical methods in the probabilistic fracture mechanics are hardly verified by experiments. Therefore, it is strongly needed to verify the probabilistic fracture mechanics through the round robin analysis. This paper describes results from the round robin analysis of flat plate with semi-elliptic cracks on the surface, conducted by the PFM Working Group of LE Subcommittee of the Japan Welding Society under the contract of the Japan Atomic Energy Research Institute and participated by Tokyo University, Yokohama National University, the Power Reactor and Nuclear Fuel Corporation, Tokyo Electric Power Co. Central Research Institute of Electric Power Industry, Toshiba Corporation, Kawasaki Heavy Industry Co. and Mitsubishi Heavy Industry Co. (author)

  2. Finite element analysis of tibial fractures

    DEFF Research Database (Denmark)

    Wong, Christian Nai En; Mikkelsen, Mikkel Peter W; Hansen, Leif Berner

    2010-01-01

    Project. The data consisted of 21,219 3D elements with a cortical shell and a trabecular core. Three types of load of torsion, a direct lateral load and axial compression were applied. RESULTS: The finite element linear static analysis resulted in relevant fracture localizations and indicated relevant...

  3. The optimal XFEM approximation for fracture analysis

    International Nuclear Information System (INIS)

    Jiang Shouyan; Du Chengbin; Ying Zongquan

    2010-01-01

    The extended finite element method (XFEM) provides an effective tool for analyzing fracture mechanics problems. A XFEM approximation consists of standard finite elements which are used in the major part of the domain and enriched elements in the enriched sub-domain for capturing special solution properties such as discontinuities and singularities. However, two issues in the standard XFEM should specially be concerned: efficient numerical integration methods and an appropriate construction of the blending elements. In the paper, an optimal XFEM approximation is proposed to overcome the disadvantage mentioned above in the standard XFEM. The modified enrichment functions are presented that can reproduced exactly everywhere in the domain. The corresponding FORTRAN program is developed for fracture analysis. A classic problem of fracture mechanics is used to benchmark the program. The results indicate that the optimal XFEM can alleviate the errors and improve numerical precision.

  4. School playground surfacing and arm fractures in children: a cluster randomized trial comparing sand to wood chip surfaces.

    Directory of Open Access Journals (Sweden)

    Andrew W Howard

    2009-12-01

    Fibar and seven schools randomized to sand that installed sand. Noncompliant schools were added to the analysis to complete a cohort type analysis by treatment received (two schools that were randomized to Fibar but installed sand and seven schools that were randomized to sand but installed Fibar. Among compliant schools, an arm fracture rate of 1.9 (95% confidence interval [CI] 0.04-6.9 per 100,000 student-months was observed for falls into sand, compared with an arm fracture rate of 9.4 (95% CI 3.7-21.4 for falls onto Fibar surfaces (p< or =0.04905. Among all schools, the arm fracture rate was 4.5 (95% CI 0.26-15.9 per 100,000 student-months for falls into sand compared with 12.9 (95% CI 5.1-30.1 for falls onto Fibar surfaces. No serious head injuries and no fatalities were observed in either group.Granitic sand playground surfaces reduce the risk of arm fractures from playground falls when compared with engineered wood fibre surfaces. Upgrading playground surfacing standards to reflect this information will prevent arm fractures.Current Controlled Trials ISRCTN02647424.

  5. Multiple Sclerosis Increases Fracture Risk: A Meta-Analysis

    Directory of Open Access Journals (Sweden)

    Guixian Dong

    2015-01-01

    Full Text Available Purpose. The association between multiple sclerosis (MS and fracture risk has been reported, but results of previous studies remain controversial and ambiguous. To assess the association between MS and fracture risk, a meta-analysis was performed. Method. Based on comprehensive searches of the PubMed, Embase, and Web of Science, we identified outcome data from all articles estimating the association between MS and fracture risk. The pooled risk ratios (RRs with 95% confidence intervals (CIs were calculated. Results. A significant association between MS and fracture risk was found. This result remained statistically significant when the adjusted RRs were combined. Subgroup analysis stratified by the site of fracture suggested significant associations between MS and tibia fracture risk, femur fracture risk, hip fracture risk, pelvis fracture risk, vertebrae fracture risk, and humerus fracture risk. In the subgroup analysis by gender, female MS patients had increased fracture risk. When stratified by history of drug use, use of antidepressants, hypnotics/anxiolytics, anticonvulsants, and glucocorticoids increased the risk of fracture risk in MS patients. Conclusions. This meta-analysis demonstrated that MS was significantly associated with fracture risk.

  6. Examination of fracture surfaces using focused ion beam milling

    International Nuclear Information System (INIS)

    Cairney, J.M.; Munroe, P.R.; Schneibel, J.H.

    2000-01-01

    Composite materials consisting of an iron aluminide matrix with composition approximately Fe-40at%Al, reinforced with a volume fraction of 40--70% ceramic particles (TiC, WC, TiB 2 or ZrB 2 ), are currently being developed. Focused ion beam milling is a relatively new tool to materials science. It uses a high resolution (<5nm), energetic beam of gallium ions to selectively sputter regions of a material, whilst also functioning as a scanning ion microscope. The milling accuracy is of the order of the beam size allowing very precise sectioning to be carried out. The focused ion beam can be used to prepare highly localized cross sections which reveal the internal sub-structure of materials, avoiding detrimental processes such as deformation, or closing of existing cracks by mechanical abrasion. An area is milled from the sample such that, upon tilting, the internal structure can be imaged. The focused ion beam therefore offers a unique opportunity to examine cross-sections of the fracture surfaces in FeAl-based composites. In the present study, the focused ion beam was used to obtain cross-sections of fracture surfaces in two composite materials, in order to examine the extent of interfacial debonding and matrix deformation, thus providing more information about the mode of fracture. These cross-sections were prepared at regions where significant debonding was observed

  7. Fracture Mechanics

    International Nuclear Information System (INIS)

    Jang, Dong Il; Jeong, Gyeong Seop; Han, Min Gu

    1992-08-01

    This book introduces basic theory and analytical solution of fracture mechanics, linear fracture mechanics, non-linear fracture mechanics, dynamic fracture mechanics, environmental fracture and fatigue fracture, application on design fracture mechanics, application on analysis of structural safety, engineering approach method on fracture mechanics, stochastic fracture mechanics, numerical analysis code and fracture toughness test and fracture toughness data. It gives descriptions of fracture mechanics to theory and analysis from application of engineering.

  8. Probabilistic fracture mechanics of nuclear structural components: consideration of transition from embedded crack to surface crack

    International Nuclear Information System (INIS)

    Yagawa, G.; Yoshimura, S.

    1999-01-01

    This paper describes a probabilistic fracture mechanics (PFM) analysis of aged nuclear reactor pressure vessel (RPV) material. New interpolation formulas of three-dimensional stress intensity factors are presented for both embedded elliptical surface cracks and semi-elliptical surface cracks. To investigate effects of transition from embedded crack to surface crack in PFM analyses, one of the PFM round-robin problems set by JSME-RC111 committee (i.e. aged RPV under normal and upset operating conditions) is solved, employing the interpolation formulas. (orig.)

  9. Reduced Fracture Finite Element Model Analysis of an Efficient Two-Scale Hybrid Embedded Fracture Model

    KAUST Repository

    Amir, Sahar Z.

    2017-06-09

    A Hybrid Embedded Fracture (HEF) model was developed to reduce various computational costs while maintaining physical accuracy (Amir and Sun, 2016). HEF splits the computations into fine scale and coarse scale. Fine scale solves analytically for the matrix-fracture flux exchange parameter. Coarse scale solves for the properties of the entire system. In literature, fractures were assumed to be either vertical or horizontal for simplification (Warren and Root, 1963). Matrix-fracture flux exchange parameter was given few equations built on that assumption (Kazemi, 1968; Lemonnier and Bourbiaux, 2010). However, such simplified cases do not apply directly for actual random fracture shapes, directions, orientations …etc. This paper shows that the HEF fine scale analytic solution (Amir and Sun, 2016) generates the flux exchange parameter found in literature for vertical and horizontal fracture cases. For other fracture cases, the flux exchange parameter changes according to the angle, slop, direction, … etc. This conclusion rises from the analysis of both: the Discrete Fracture Network (DFN) and the HEF schemes. The behavior of both schemes is analyzed with exactly similar fracture conditions and the results are shown and discussed. Then, a generalization is illustrated for any slightly compressible single-phase fluid within fractured porous media and its results are discussed.

  10. Reduced Fracture Finite Element Model Analysis of an Efficient Two-Scale Hybrid Embedded Fracture Model

    KAUST Repository

    Amir, Sahar Z.; Chen, Huangxin; Sun, Shuyu

    2017-01-01

    A Hybrid Embedded Fracture (HEF) model was developed to reduce various computational costs while maintaining physical accuracy (Amir and Sun, 2016). HEF splits the computations into fine scale and coarse scale. Fine scale solves analytically for the matrix-fracture flux exchange parameter. Coarse scale solves for the properties of the entire system. In literature, fractures were assumed to be either vertical or horizontal for simplification (Warren and Root, 1963). Matrix-fracture flux exchange parameter was given few equations built on that assumption (Kazemi, 1968; Lemonnier and Bourbiaux, 2010). However, such simplified cases do not apply directly for actual random fracture shapes, directions, orientations …etc. This paper shows that the HEF fine scale analytic solution (Amir and Sun, 2016) generates the flux exchange parameter found in literature for vertical and horizontal fracture cases. For other fracture cases, the flux exchange parameter changes according to the angle, slop, direction, … etc. This conclusion rises from the analysis of both: the Discrete Fracture Network (DFN) and the HEF schemes. The behavior of both schemes is analyzed with exactly similar fracture conditions and the results are shown and discussed. Then, a generalization is illustrated for any slightly compressible single-phase fluid within fractured porous media and its results are discussed.

  11. Plain film analysis of acetabular fracture

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chang Soo; Han, Sang Suk; Yoon, Eu Giene; Cha, Seong Sook; Eun, Tchoong Kie; Chung, Duck Hwan [Inje Medical College Paik Hospital, Pusan (Korea, Republic of)

    1986-02-15

    Acetabular fracture can result in severe limitation of the motion of the hip joint, which supports total weight of human body. Because of different methods of surgical approach according to fracture type, precise interpretation of X-ray films of acetabular fracture is required. We reviewed 38 cases of simple X-ray films showing acetabular fracture. The results were as follows: 1. Almost 60% of the cases-were in their 2nd and 3rd decades. 2. Twenty cases were male, and 18 cases were female. 3. The most common cause of the injury was traffic accident (33 cases, 86.8%), followed by fall down (4 cases, 10.5%), and slip down (1 case, 2.7%). 4. Elementary fractures were 21 cases (55.3%), and associated fractures were 17 cases (44.7%). 5. Among elementary fractures, posterior wall fractures were 9 cases (23.7%), followed by anterior column fractures (8 cases, 21.1%), anterior wall fractures (4 cases, 10.5%). 6. Among associated fractures, T-shaped fractures were 8 cases (21.1%), followed by both column fractures (6 cases, 15.8%), anterior and hemitransverse fractures (3 cases, 7.8%). 7. Other pelvic bone fractures associated with the acetabular fracture were as follows: fractures of contralateral pubic rami (6 cases, 15.8%) contralateral iliac bone (1 case, 2.6%) and ipsilateral iliac bone (1 case, 2.6%). 8. Injuries of other organs adjacent to the acetabulum were as follows: rupture of the bladder (3 cases, 7.9%), urethra (2 cases, 5.3%) and uterus (1 cases, 2.6%)

  12. Plain film analysis of acetabular fracture

    International Nuclear Information System (INIS)

    Kim, Chang Soo; Han, Sang Suk; Yoon, Eu Giene; Cha, Seong Sook; Eun, Tchoong Kie; Chung, Duck Hwan

    1986-01-01

    Acetabular fracture can result in severe limitation of the motion of the hip joint, which supports total weight of human body. Because of different methods of surgical approach according to fracture type, precise interpretation of X-ray films of acetabular fracture is required. We reviewed 38 cases of simple X-ray films showing acetabular fracture. The results were as follows: 1. Almost 60% of the cases-were in their 2nd and 3rd decades. 2. Twenty cases were male, and 18 cases were female. 3. The most common cause of the injury was traffic accident (33 cases, 86.8%), followed by fall down (4 cases, 10.5%), and slip down (1 case, 2.7%). 4. Elementary fractures were 21 cases (55.3%), and associated fractures were 17 cases (44.7%). 5. Among elementary fractures, posterior wall fractures were 9 cases (23.7%), followed by anterior column fractures (8 cases, 21.1%), anterior wall fractures (4 cases, 10.5%). 6. Among associated fractures, T-shaped fractures were 8 cases (21.1%), followed by both column fractures (6 cases, 15.8%), anterior and hemitransverse fractures (3 cases, 7.8%). 7. Other pelvic bone fractures associated with the acetabular fracture were as follows: fractures of contralateral pubic rami (6 cases, 15.8%) contralateral iliac bone (1 case, 2.6%) and ipsilateral iliac bone (1 case, 2.6%). 8. Injuries of other organs adjacent to the acetabulum were as follows: rupture of the bladder (3 cases, 7.9%), urethra (2 cases, 5.3%) and uterus (1 cases, 2.6%).

  13. Interpretation and significance of reverse chevron-shaped markings on fracture surfaces of API X100 pipeline steels

    International Nuclear Information System (INIS)

    Sowards, Jeffrey W.; McCowan, Chris N.; Drexler, Elizabeth S.

    2012-01-01

    Highlights: ► We investigated fractures of X100 steel linepine produced during fracture mechanics testing. ► Fractures exhibited a unique chevron pattern that points in the direction of crack propagation. ► A qualitative model is proposed to explain the fracture pattern formation. ► Findings indicate that careful interpretation of ductile material fractures is necessary. - Abstract: Fracture surfaces of X100 pipeline steels were examined with optical and electron microscopy after crack tip opening angle fracture testing. Some fracture surfaces exhibited chevron-shaped fracture patterns that are markedly different from classic chevron fracture. The chevron-shaped markings on the X100 fracture surfaces point in the direction of crack growth, rather than towards the location of fracture initiation, as observed in classic cases of chevron fracture. Existing models, predicting formation of chevron fracture patterns, do not explain the fracture behavior observed for X100 steel. A mechanism is proposed where reverse chevron-shaped patterns are developed due to the shape of the crack front itself. The chevron shape forms as a result of crack tunneling, and the overall pattern is developed on the fracture surface due to intermittent crack growth, resulting in alternating regions (bands) of fast fracture and slower, more ductile fracture. The contrast between these bands of alternating fracture defines the chevron. Care should be taken during interpretation of intermittent chevron markings on fractures of ductile materials, as they may point away from rather than towards the origin of fracture.

  14. Crack propagation in disordered materials: how to decipher fracture surfaces

    Science.gov (United States)

    Ponson, L.

    For a half-century, engineers know how to describe and predict the propagation of a crack in a model elastic homogeneous medium. The case of real materials is much more complex. Indeed, we do not know how to relate their lifetime or their resistance to their microstructure. To achieve such a prediction, understanding the role of the microstructural disorder on the behavior of a crack is determinant. Fracture surfaces represent a promising field of investigation to address this question. From the study of various disordered materials, we propose a statistical description of their roughness and determine to which extent their properties are dependent of the material. We show that fracture surfaces display an anisotropic scale invariant geometry characterized by two universal exponents. Glass ceramics is then studied because its microstructure can be tuned in a controlled manner. Their fracture surfaces display the same general anisotropic properties but with surprisingly low exponents independent of the detail of the ceramics microstructure. This suggests the existence of a second universality class in failure problems. Using finally theoretical tools from out-of-equilibrium statistical physics and fracture mechanics, we relate the statistical properties of fracture surfaces with the mechanisms occurring at the microscopic scale during the failure of a material. In particular, we show that the first class of fracture surfaces results from a failure involving damage processes while the second one results from a perfectly brittle failure. Propagation de fissures dans les matériaux désordonnés : comment déchiffrer les surfaces de rupture. Depuis près d'un demi-siècle, les ingénieurs savent décrire et prévoir la propagation d'une fissure dans un milieu élastique homogène modèle. Le cas des matériaux réels est beaucoup plus complexe. En effet, on ne sait pas relier leur durée de vie ou leur résistance à leur microstructure. Passage obligé avant de telles

  15. Fracture zones constrained by neutral surfaces in a fault-related fold: Insights from the Kelasu tectonic zone, Kuqa Depression

    Science.gov (United States)

    Sun, Shuai; Hou, Guiting; Zheng, Chunfang

    2017-11-01

    Stress variation associated with folding is one of the controlling factors in the development of tectonic fractures, however, little attention has been paid to the influence of neutral surfaces during folding on fracture distribution in a fault-related fold. In this study, we take the Cretaceous Bashijiqike Formation in the Kuqa Depression as an example and analyze the distribution of tectonic fractures in fault-related folds by core observation and logging data analysis. Three fracture zones are identified in a fault-related fold: a tensile zone, a transition zone and a compressive zone, which may be constrained by two neutral surfaces of fold. Well correlation reveals that the tensile zone and the transition zone reach the maximum thickness at the fold hinge and get thinner in the fold limbs. A 2D viscoelastic stress field model of a fault-related fold was constructed to further investigate the mechanism of fracturing. Statistical and numerical analysis reveal that the tensile zone and the transition zone become thicker with decreasing interlimb angle. Stress variation associated with folding is the first level of control over the general pattern of fracture distribution while faulting is a secondary control over the development of local fractures in a fault-related fold.

  16. Spartan Release Engagement Mechanism (REM) stress and fracture analysis

    Science.gov (United States)

    Marlowe, D. S.; West, E. J.

    1984-01-01

    The revised stress and fracture analysis of the Spartan REM hardware for current load conditions and mass properties is presented. The stress analysis was performed using a NASTRAN math model of the Spartan REM adapter, base, and payload. Appendix A contains the material properties, loads, and stress analysis of the hardware. The computer output and model description are in Appendix B. Factors of safety used in the stress analysis were 1.4 on tested items and 2.0 on all other items. Fracture analysis of the items considered fracture critical was accomplished using the MSFC Crack Growth Analysis code. Loads and stresses were obtaind from the stress analysis. The fracture analysis notes are located in Appendix A and the computer output in Appendix B. All items analyzed met design and fracture criteria.

  17. Finding Large Aperture Fractures in Geothermal Resource Areas Using a Three-Component Long-Offset Surface Seismic Survey, PSInSAR and Kinematic Structural Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Teplow, William J. [US Geothermal, Inc., Boise, ID (United States); Warren, Ian [US Geothermal, Inc., Boise, ID (United States)

    2015-08-12

    The DOE cost-share program applied innovative and cutting edge seismic surveying and processing, permanent scatter interferometry-synthetic aperture radar (PSInSAR) and structural kinematics to the exploration problem of locating and mapping largeaperture fractures (LAFs) for the purpose of targeting geothermal production wells. The San Emidio geothermal resource area, which is under lease to USG, contains production wells that have encountered and currently produce from LAFs in the southern half of the resource area (Figure 2). The USG lease block, incorporating the northern extension of the San Emidio geothermal resource, extends 3 miles north of the operating wellfield. The northern lease block was known to contain shallow thermal waters but was previously unexplored by deep drilling. Results of the Phase 1 exploration program are described in detail in the Phase 1 Final Report (Teplow et al., 2011). The DOE cost shared program was completed as planned on September 30, 2014. This report summarizes results from all of Phase 1 and 2 activities.

  18. Analysis of blowout fractures using cine mode MRI

    International Nuclear Information System (INIS)

    Kawahara, Masaaki; Shiihara, Kumiko; Kimura, Hisashi; Fukai, Sakuko; Tabuchi, Akio; Kojo, Tuyoshi

    1995-01-01

    By observing conventional CT and MRI images, it is difficult to distinguish extension failure from adhesion, bone fracture or damage to the extraocular muscle, any one of which may be the direct cause of the eye movement disturbance accompanying blowout fracture. We therefore carried out dynamic analysis of eye movement disturbance using a cine mode MRI. We put seven fixation points in the gantry of the MRI and filmed eye movement disturbances by the gradient echo method, using a surface coil and holding the vision on each fixation point. We also video recorded the CRT monitor of the MRI to obtain dynamic MRI images. The subjects comprised 5 cases (7-23 years old). In 4 cases, we started orthoptic treatment, saccadic eye movement training, convergence training and fusional amplitude training after surgery, with only orthoptic treatment in the 5 th case. In all cases, fusion area improvement was recognized during training. In 2 cases examined by cine mode MRI before and after surgery, we observed improved eye movement after training, the effectiveness of which was thereby proven. Also, using cine mode MRI we were able to determine the character of incarcerated tissue and the cause of eye movement disturbance. We conclude that it blowout fracture, cine mode MRI may be useful in selecting treatment and observing its effectiveness. (author)

  19. Remodeled articular surface after surgical fixation of patella fracture in a child

    Directory of Open Access Journals (Sweden)

    Moruf Babatunde Yusuf

    2017-01-01

    Full Text Available Patella fracture is uncommon in pediatric age group and their patella is better preserved in any class of patella fracture. We reported a case of a 13-year-old male with right patella fracture nonunion. He had open reduction and internal fixation using tension band wire device. Fracture union was monitored with serial radiographs and he was followed up for 60 weeks. There was articular surface step after surgical fixation of the patella fracture. At 34 weeks postoperative, there was complete remodeling of the articular surface with good knee function after removal of the tension band wire. Children have good capacity of bone remodeling after fracture. Little retropatella step in a child after patella fracture surgical fixation will remodel with healing.

  20. Well test analysis in fractured media

    Energy Technology Data Exchange (ETDEWEB)

    Karasaki, K.

    1987-04-01

    The behavior of fracture systems under well test conditions and methods for analyzing well test data from fractured media are investigated. Several analytical models are developed to be used for analyzing well test data from fractured media. Numerical tools that may be used to simulate fluid flow in fractured media are also presented. Three types of composite models for constant flux tests are investigated. These models are based on the assumption that a fracture system under well test conditions may be represented by two concentric regions, one representing a small number of fractures that dominates flow near the well, and the other representing average conditions farther away from the well. Type curves are presented that can be used to find the flow parameters of these two regions and the extent of the inner concentric region. Several slug test models with different geometric conditions that may be present in fractured media are also investigated. A finite element model that can simulate transient fluid flow in fracture networks is used to study the behavior of various two-dimensional fracture systems under well test conditions. A mesh generator that can be used to model mass and heat flow in a fractured-porous media is presented.

  1. Fractal analysis of fracture increasing spontaneous imbibition in porous media with gas-saturated

    KAUST Repository

    Cai, Jianchao; Sun, Shuyu

    2013-01-01

    Spontaneous imbibition (SI) of wetting liquid into matrix blocks due to capillary pressure is regarded as an important recovery mechanism in low permeability fractured reservoir. In this paper, an analytical model is proposed for characterizing SI horizontally from a single plane fracture into gas-saturated matrix blocks. The presented model is based on the fractal character of pores in porous matrix, with gravity force included in the entire imbibition process. The accumulated mass of wetting liquid imbibed into matrix blocks is related to a number of factors such as contact area, pore fractal dimension, tortuosity, maximum pore size, porosity, liquid density and viscosity, surface tension, contact angle, as well as height and tilt angle of the fracture. The mechanism of fracture-enhanced SI is analyzed accordingly. Because of the effect of fracture, the gravity force is positive to imbibition process. Additionally, the farther away from the fracture top of the pore, the more influential the hydrostatic pressure is upon the imbibition action. The presented fractal analysis of horizontal spontaneous imbibition from a single fracture could also shed light on the scaling study of the mass transfer function between matrix and fracture system of fractured reservoirs. © 2013 World Scientific Publishing Company.

  2. Fractal analysis of fracture increasing spontaneous imbibition in porous media with gas-saturated

    KAUST Repository

    Cai, Jianchao

    2013-08-01

    Spontaneous imbibition (SI) of wetting liquid into matrix blocks due to capillary pressure is regarded as an important recovery mechanism in low permeability fractured reservoir. In this paper, an analytical model is proposed for characterizing SI horizontally from a single plane fracture into gas-saturated matrix blocks. The presented model is based on the fractal character of pores in porous matrix, with gravity force included in the entire imbibition process. The accumulated mass of wetting liquid imbibed into matrix blocks is related to a number of factors such as contact area, pore fractal dimension, tortuosity, maximum pore size, porosity, liquid density and viscosity, surface tension, contact angle, as well as height and tilt angle of the fracture. The mechanism of fracture-enhanced SI is analyzed accordingly. Because of the effect of fracture, the gravity force is positive to imbibition process. Additionally, the farther away from the fracture top of the pore, the more influential the hydrostatic pressure is upon the imbibition action. The presented fractal analysis of horizontal spontaneous imbibition from a single fracture could also shed light on the scaling study of the mass transfer function between matrix and fracture system of fractured reservoirs. © 2013 World Scientific Publishing Company.

  3. Fracture Testing with Surface Crack Specimens. [especially the residual tensile strength test

    Science.gov (United States)

    Orange, T. W.

    1974-01-01

    Recommendations are given for the design, preparation, and static fracture testing of surface crack specimens. The recommendations are preceded by background information including discussions of stress intensity factors, crack opening displacements, and fracture toughness values associated with surface crack specimens. Cyclic load and sustained load tests are discussed briefly.

  4. [Mechanics analysis of fracture of orthodontic wires].

    Science.gov (United States)

    Wang, Yeping; Sun, Xiaoye; Zhang, Longqi

    2003-03-01

    Fracture problem of orthodontic wires was discussed in this paper. The calculation formulae of bending stress and tensile stress were obtained. All main factors that affect bending stress and tensile stress of orthodontic wires were analyzed and discussed. It was concluded that the main causes of fracture of orthodontic wires were fatigue and static disruption. Some improving proposals for preventing fracture of orthodontic wires were put forward.

  5. Well test analysis in fractured media

    Energy Technology Data Exchange (ETDEWEB)

    Karasaki, K.

    1986-04-01

    In this study the behavior of fracture systems under well test conditions and methods for analyzing well test data from fractured media are investigated. Several analytical models are developed to be used for analyzing well test data from fractured media. Numerical tools that may be used to simulate fluid flow in fractured media are also presented. Three types of composite models for constant flux tests are investigated. Several slug test models with different geometric conditions that may be present in fractured media are also investigated. A finite element model that can simulate transient fluid flow in fracture networks is used to study the behavior of various two-dimensional fracture systems under well test conditions. A mesh generator that can be used to model mass and heat flow in a fractured-porous media is presented. This model develops an explicit solution in the porous matrix as well as in the discrete fractures. Because the model does not require the assumptions of the conventional double porosity approach, it may be used to simulate cases where double porosity models fail.

  6. Characterization of fracture networks for fluid flow analysis

    International Nuclear Information System (INIS)

    Long, J.C.S.; Billaux, D.; Hestir, K.; Majer, E.L.; Peterson, J.; Karasaki, K.; Nihei, K.; Gentier, S.; Cox, L.

    1989-06-01

    The analysis of fluid flow through fractured rocks is difficult because the only way to assign hydraulic parameters to fractures is to perform hydraulic tests. However, the interpretation of such tests, or ''inversion'' of the data, requires at least that we know the geometric pattern formed by the fractures. Combining a statistical approach with geophysical data may be extremely helpful in defining the fracture geometry. Cross-hole geophysics, either seismic or radar, can provide tomograms which are pixel maps of the velocity or attenuation anomalies in the rock. These anomalies are often due to fracture zones. Therefore, tomograms can be used to identify fracture zones and provide information about the structure within the fracture zones. This structural information can be used as the basis for simulating the degree of fracturing within the zones. Well tests can then be used to further refine the model. Because the fracture network is only partially connected, the resulting geometry of the flow paths may have fractal properties. We are studying the behavior of well tests under such geometry. Through understanding of this behavior, it may be possible to use inverse techniques to refine the a priori assignment of fractures and their conductances such that we obtain the best fit to a series of well test results simultaneously. The methodology described here is under development and currently being applied to several field sites. 4 refs., 14 figs

  7. Selection of pipeline steels with an engineering fracture mechanical analysis

    Energy Technology Data Exchange (ETDEWEB)

    Stenbacka, N [Swedish State Power Board, Vaellingby

    1985-01-01

    Selection of pipeline steels is discussed on the basis of two mutually independent failure mechanisms: elastic fracture and plastic collapse. The presentation is restricted to axial flaws. A formal analysis shows that brittle fracture in modern pipelines has no high priority in design, since steels used today have a high fracture toughness. Instead, a case of practical concern is tha plastic collapse mode, where failure is flow stress controlled. Conditions governing this design case are specified. In conjunction with this, criterions for material selection with regard to fracture toughness is presented.

  8. From analysis to surface

    DEFF Research Database (Denmark)

    Bemman, Brian; Meredith, David

    it with a “ground truth” analysis of the same music pro- duced by a human expert (see, in particular, [5]). In this paper, we explore the problem of generating an encoding of the musical surface of a work automatically from a systematic encoding of an analysis. The ability to do this depends on one having...... an effective (i.e., comput- able), correct and complete description of some aspect of the structure of the music. Generating the surface struc- ture of a piece from an analysis in this manner serves as a proof of the analysis' correctness, effectiveness and com- pleteness. We present a reductive analysis......In recent years, a significant body of research has focused on developing algorithms for computing analyses of mu- sical works automatically from encodings of these works' surfaces [3,4,7,10,11]. The quality of the output of such analysis algorithms is typically evaluated by comparing...

  9. Measurement of kinaesthetic properties of in-brine table olives by microstructure of fracture surface, sensory evaluation and texture profile analysis (TPA).

    Science.gov (United States)

    Lanza, Barbara; Amoruso, Filomena

    2018-02-02

    A series of transformations occur in olive fruit both during ripening and processing. In particular, significant changes in the microstructural composition affect the flavour, texture, nutrients and overall quality of the end product. Texture is one of the sensory quality attributes of greatest importance to consumer acceptance. In the present work, kinaesthetic properties of in-brine table olives of three cultivars of Olea europaea L. (Bella di Cerignola, Peranzana and Taggiasca cvs) were provided by several measurements of olive tissue texture by sensory, rheological and microstructural approaches. Olives at the same stage of ripening and processed with the same technology, but belonging to different cultivars, showed significant differences at microstructural, sensorial and rheological levels. To describe the relationship between the three variables, multiple regression analysis and principal component analysis were chosen. Differences in microstructure were closely related both in terms of hardness measured by texture profile analysis and hardness measured by sensory analysis. The information provided could be an aid for screening and training of a sensory panel. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

  10. Fracture analysis of tube boiler for physical explosion accident.

    Science.gov (United States)

    Kim, Eui Soo

    2017-09-01

    Material and failure analysis techniques are key tools for determining causation in case of explosive and bursting accident result from material and process defect of product in the field of forensic science. The boiler rupture generated by defect of the welding division, corrosion, overheating and degradation of the material have devastating power. If weak division of boiler burner is fractured by internal pressure, saturated vapor and water is vaporized suddenly. At that time, volume of the saturated vapor and water increases up to thousands of volume. This failure of boiler burner can lead to a fatal disaster. In order to prevent an explosion and of the boiler, it is critical to introduce a systematic investigation and prevention measures in advance. In this research, the cause of boiler failure is investigated through forensic engineering method. Specifically, the failure mechanism will be identified by fractography using scanning electron microscopes (SEM) and Optical Microscopes (OM) and mechanical characterizations. This paper presents a failure analysis of household welding joints for the water tank of a household boiler burner. Visual inspection was performed to find out the characteristics of the fracture of the as-received material. Also, the micro-structural changes such as grain growth and carbide coarsening were examined by optical microscope. Detailed studies of fracture surfaces were made to find out the crack propagation on the weld joint of a boiler burner. It was concluded that the rupture may be caused by overheating induced by insufficient water on the boiler, and it could be accelerated by the metal temperature increase. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. A New Approach to the Modeling and Analysis of Fracture through Extension of Continuum Mechanics to the Nanoscale

    KAUST Repository

    Sendova, T.; Walton, J. R.

    2010-01-01

    In this paper we focus on the analysis of the partial differential equations arising from a new approach to modeling brittle fracture based on an extension of continuum mechanics to the nanoscale. It is shown that ascribing constant surface tension

  12. Analysis Strategy for Fracture Assessment of Defects in Ductile Materials

    Energy Technology Data Exchange (ETDEWEB)

    Dillstroem, Peter; Andersson, Magnus; Sattari-Far, Iradj; Weilin Zang (Inspecta Technology AB, Stockholm (Sweden))

    2009-06-15

    The main purpose of this work is to investigate the significance of the residual stresses for defects (cracks) in ductile materials with nuclear applications, when the applied primary (mechanical) loads are high. The treatment of weld-induced stresses as expressed in the SACC/ProSACC handbook and other fracture assessment procedures such as the ASME XI code and the R6-method is believed to be conservative for ductile materials. This is because of the general approach not to account for the improved fracture resistance caused by ductile tearing. Furthermore, there is experimental evidence that the contribution of residual stresses to fracture diminishes as the degree of yielding increases to a high level. However, neglecting weld-induced stresses in general, though, is doubtful for loads that are mostly secondary (e.g. thermal shocks) and for materials which are not ductile enough to be limit load controlled. Both thin-walled and thick-walled pipes containing surface cracks are studied here. This is done by calculating the relative contribution from the weld residual stresses to CTOD and the J-integral. Both circumferential and axial cracks are analysed. Three different crack geometries are studied here by using the finite element method (FEM). (i) 2D axisymmetric modelling of a V-joint weld in a thin-walled pipe. (ii) 2D axisymmetric modelling of a V-joint weld in a thick-walled pipe. (iii) 3D modelling of a X-joint weld in a thick-walled pipe. t. Each crack configuration is analysed for two load cases; (1) Only primary (mechanical) loading is applied to the model, (2) Both secondary stresses and primary loading are applied to the model. Also presented in this report are some published experimental investigations conducted on cracked components of ductile materials subjected to both primary and secondary stresses. Based on the outcome of this study, an analysis strategy for fracture assessment of defects in ductile materials of nuclear components is proposed. A new

  13. Analysis Strategy for Fracture Assessment of Defects in Ductile Materials

    International Nuclear Information System (INIS)

    Dillstroem, Peter; Andersson, Magnus; Sattari-Far, Iradj; Weilin Zang

    2009-06-01

    The main purpose of this work is to investigate the significance of the residual stresses for defects (cracks) in ductile materials with nuclear applications, when the applied primary (mechanical) loads are high. The treatment of weld-induced stresses as expressed in the SACC/ProSACC handbook and other fracture assessment procedures such as the ASME XI code and the R6-method is believed to be conservative for ductile materials. This is because of the general approach not to account for the improved fracture resistance caused by ductile tearing. Furthermore, there is experimental evidence that the contribution of residual stresses to fracture diminishes as the degree of yielding increases to a high level. However, neglecting weld-induced stresses in general, though, is doubtful for loads that are mostly secondary (e.g. thermal shocks) and for materials which are not ductile enough to be limit load controlled. Both thin-walled and thick-walled pipes containing surface cracks are studied here. This is done by calculating the relative contribution from the weld residual stresses to CTOD and the J-integral. Both circumferential and axial cracks are analysed. Three different crack geometries are studied here by using the finite element method (FEM). (i) 2D axisymmetric modelling of a V-joint weld in a thin-walled pipe. (ii) 2D axisymmetric modelling of a V-joint weld in a thick-walled pipe. (iii) 3D modelling of a X-joint weld in a thick-walled pipe. t. Each crack configuration is analysed for two load cases; (1) Only primary (mechanical) loading is applied to the model, (2) Both secondary stresses and primary loading are applied to the model. Also presented in this report are some published experimental investigations conducted on cracked components of ductile materials subjected to both primary and secondary stresses. Based on the outcome of this study, an analysis strategy for fracture assessment of defects in ductile materials of nuclear components is proposed. A new

  14. Analysis of fracture patterns and local stress field variations in fractured reservoirs

    Science.gov (United States)

    Deckert, Hagen; Drews, Michael; Fremgen, Dominik; Wellmann, J. Florian

    2010-05-01

    A meaningful qualitative evaluation of permeabilities in fractured reservoirs in geothermal or hydrocarbon industry requires the spatial description of the existing discontinuity pattern within the area of interest and an analysis how these fractures might behave under given stress fields. This combined information can then be used for better estimating preferred fluid pathway directions within the reservoir, which is of particular interest for defining potential drilling sites. A description of the spatial fracture pattern mainly includes the orientation of rock discontinuities, spacing relationships between single fractures and their lateral extent. We have examined and quantified fracture patterns in several outcrops of granite at the Costa Brava, Spain, and in the Black Forest, Germany, for describing reservoir characteristics. For our analysis of fracture patterns we have used photogrammetric methods to create high-resolution georeferenced digital 3D images of outcrop walls. The advantage of this approach, compared to conventional methods for fracture analysis, is that it provides a better 3D description of the fracture geometry as the entity of position, extent and orientation of single fractures with respect to their surrounding neighbors is conserved. Hence for instance, the method allows generating fracture density maps, which can be used for a better description of the spatial distribution of discontinuities in a given outcrop. Using photogrammetric techniques also has the advantage to acquire very large data sets providing statistically sound results. To assess whether the recorded discontinuities might act as fluid pathways information on the stress field is needed. A 3D model of the regional tectonic structure was created and the geometry of the faults was put into a mechanical 3D Boundary Element (BE) Model. The model takes into account the elastic material properties of the geological units and the orientation of single fault segments. The

  15. Analysis of PITFL injuries in rotationally unstable ankle fractures.

    Science.gov (United States)

    Warner, Stephen J; Garner, Matthew R; Schottel, Patrick C; Hinds, Richard M; Loftus, Michael L; Lorich, Dean G

    2015-04-01

    Reduction and stabilization of the syndesmosis in unstable ankle fractures is important for ankle mortise congruity and restoration of normal tibiotalar contact forces. Of the syndesmotic ligaments, the posterior inferior tibiofibular ligament (PITFL) provides the most strength for maintaining syndesmotic stability, and previous work has demonstrated the significance of restoring PITFL function when it remains attached to a posterior malleolus fracture fragment. However, little is known regarding the nature of a PITFL injury in the absence of a posterior malleolus fracture. The goal of this study was to describe the PITFL injury pattern based on magnetic resonance imaging (MRI) and intraoperative observation. A prospective database of all operatively treated ankle fractures by a single surgeon was used to identify all supination-external rotation (SER) types III and IV ankle fracture patients with complete preoperative orthogonal ankle radiographs and MRI. All patients with a posterior malleolus fracture were excluded. Using a combination of preoperative imaging and intraoperative findings, we analyzed the nature of injuries to the PITFL. In total, 185 SER III and IV operatively treated ankle fractures with complete imaging were initially identified. Analysis of the preoperative imaging and operative reports revealed 34% (63/185) had a posterior malleolus fracture and were excluded. From the remaining 122 ankle fractures, the PITFL was delaminated from the posterior malleolus in 97% (119/122) of cases. A smaller proportion (3%; 3/122) had an intrasubstance PITFL rupture. Accurate and stable syndesmotic reduction is a significant component of restoring the ankle mortise after unstable ankle fractures. In our large cohort of rotationally unstable ankle fractures without posterior malleolus fractures, we found that most PITFL injuries occur as a delamination off the posterior malleolus. This predictable PITFL injury pattern may be used to guide new methods for

  16. Morphology Analysis of Cu Film Fractures in Sandwiched Methylmethacrylate Plates

    Directory of Open Access Journals (Sweden)

    Cristiano Fidani

    2015-06-01

    Full Text Available Thin films of Cu were evaporated on solid plates of polymethylmethacrylate (PMMA. A polymerization process was made to realize sandwiched structure to protect the Cu films. Fracturing of the metal film surface was observed with several morphologies showing two different fracture systems. Surface film morphology was analysed in terms of the distribution area of the islands and contour fractal dimension. The island areas showed a maximum corresponding to 42 nm of the Cu thickness, it was also the threshold to observe the second fracture system. The fractures pattern resulted to be scale invariant with fractal dimensions between 1.55 and 1.7. The minimum fractal dimension also occurred at the film thickness corresponding to the maximum island area. The reported effects can be understood on the basis of different thermal expansion coefficients of the two materials and their thermally induced adhesion.DOI: http://dx.doi.org/10.5755/j01.ms.21.2.6518

  17. Fractographic analysis of fractured dental implant components

    Directory of Open Access Journals (Sweden)

    Chih-Ling Chang

    2013-03-01

    Conclusion: To avoid implant fracture, certain underlying mechanical risk factors should be noted such as patients with a habit of bruxism, bridgework with a cantilever design, or two implants installed in a line in the posterior mandible.

  18. Stochastic and fractal analysis of fracture trajectories

    Science.gov (United States)

    Bessendorf, Michael H.

    1987-01-01

    Analyses of fracture trajectories are used to investigate structures that fall between 'micro' and 'macro' scales. It was shown that fracture trajectories belong to the class of nonstationary processes. It was also found that correlation distance, which may be related to a characteristic size of a fracture process, increases with crack length. An assemblage of crack trajectory processes may be considered as a diffusive process. Chudnovsky (1981-1985) introduced a 'crack diffusion coefficient' d which reflects the ability of the material to deviate the crack trajectory from the most energetically efficient path and thus links the material toughness to its structure. For the set of fracture trajectories in AISI 304 steel, d was found to be equal to 1.04 microns. The fractal dimension D for the same set of trajectories was found to be 1.133.

  19. Effective Wettability of Heterogenous Fracture Surfaces Using the Lattice-Boltzmann Method

    Science.gov (United States)

    E Santos, J.; Prodanovic, M.; Landry, C. J.

    2017-12-01

    Fracture walls in the subsurface are often structured by minerals of different composition (potentially further altered in contact with fluids during hydrocarbon extraction or CO2 sequestration), this yields in a heterogeneous wettability of the surface in contact with the fluids. The focus of our work is to study how surfaces presenting different mineralogy and roughness affect multiphase flow in fractures. Using the Shan-Chen model of the lattice-Boltzmann method (LBM) we define fluid interaction and surface attraction parameters to simulate a system of a wetting and a non-wetting fluid. In this work, we use synthetically created fractures presenting different arrangements of wetting and non-wetting patches, and with or without roughness; representative of different mineralogy, similar workflow can be applied to fractures extracted from X-ray microtomography images of fractures porous media. The results from the LBM simulations provide an insight on how the distribution of mineralogy and surface roughness are related with the observed macroscopic contact angle. We present a comparison between the published analytical models, and our results based on surface areas, spatial distribution and local fracture aperture. The understanding of the variables that affect the contact angle is useful for the comprehension of multiphase processes in naturally fractured reservoirs like primary oil production, enhanced oil recovery and CO2 sequestration. The macroscopic contact angle analytical equations for heterogeneous surfaces with variable roughness are no longer valid in highly heterogeneous systems; we quantify the difference thus offering an alternative to analytical models.

  20. Applications of surface analysis and surface theory in tribology

    Science.gov (United States)

    Ferrante, John

    1989-01-01

    Tribology, the study of adhesion, friction and wear of materials, is a complex field which requires a knowledge of solid state physics, surface physics, chemistry, material science, and mechanical engineering. It has been dominated, however, by the more practical need to make equipment work. With the advent of surface analysis and advances in surface and solid-state theory, a new dimension has been added to the analysis of interactions at tribological interfaces. In this paper the applications of tribological studies and their limitations are presented. Examples from research at the NASA Lewis Research Center are given. Emphasis is on fundamental studies involving the effects of monolayer coverage and thick films on friction and wear. A summary of the current status of theoretical calculations of defect energetics is presented. In addition, some new theoretical techniques which enable simplified quantitative calculations of adhesion, fracture, and friction are discussed.

  1. Uncertainty analysis on probabilistic fracture mechanics assessment methodology

    International Nuclear Information System (INIS)

    Rastogi, Rohit; Vinod, Gopika; Chandra, Vikas; Bhasin, Vivek; Babar, A.K.; Rao, V.V.S.S.; Vaze, K.K.; Kushwaha, H.S.; Venkat-Raj, V.

    1999-01-01

    Fracture Mechanics has found a profound usage in the area of design of components and assessing fitness for purpose/residual life estimation of an operating component. Since defect size and material properties are statistically distributed, various probabilistic approaches have been employed for the computation of fracture probability. Monte Carlo Simulation is one such procedure towards the analysis of fracture probability. This paper deals with uncertainty analysis using the Monte Carlo Simulation methods. These methods were developed based on the R6 failure assessment procedure, which has been widely used in analysing the integrity of structures. The application of this method is illustrated with a case study. (author)

  2. Analysis of Flow Behavior for Acid Fracturing Wells in Fractured-Vuggy Carbonate Reservoirs

    Directory of Open Access Journals (Sweden)

    Mingxian Wang

    2018-01-01

    Full Text Available This study develops a mathematical model for transient flow analysis of acid fracturing wells in fractured-vuggy carbonate reservoirs. This model considers a composite system with the inner region containing finite number of artificial fractures and wormholes and the outer region showing a triple-porosity medium. Both analytical and numerical solutions are derived in this work, and the comparison between two solutions verifies the model accurately. Flow behavior is analyzed thoroughly by examining the standard log-log type curves. Flow in this composite system can be divided into six or eight main flow regimes comprehensively. Three or two characteristic V-shaped segments can be observed on pressure derivative curves. Each V-shaped segment corresponds to a specific flow regime. One or two of the V-shaped segments may be absent in particular cases. Effects of interregional diffusivity ratio and interregional conductivity ratio on transient responses are strong in the early-flow period. The shape and position of type curves are also influenced by interporosity coefficients, storativity ratios, and reservoir radius significantly. Finally, we show the differences between our model and the similar model with single fracture or without acid fracturing and further investigate the pseudo-skin factor caused by acid fracturing.

  3. CANDIDATE GENE ANALYSIS IN ISRAELI SOLDIERS WITH STRESS FRACTURES

    Directory of Open Access Journals (Sweden)

    Ran Yanovich

    2012-03-01

    Full Text Available To investigate the association of polymorphisms within candidate genes which we hypothesized may contribute to stress fracture predisposition, a case-control, cross- sectional study design was employed. Genotyping 268 Single Nucleotide Polymorphisms- SNPs within 17 genes in 385 Israeli young male and female recruits (182 with and 203 without stress fractures. Twenty-five polymorphisms within 9 genes (NR3C1, ANKH, VDR, ROR2, CALCR, IL6, COL1A2, CBG, and LRP4 showed statistically significant differences (p < 0.05 in the distribution between stress fracture cases and non stress fracture controls. Seventeen genetic variants were associated with an increased stress fracture risk, and eight variants with a decreased stress fracture risk. None of the SNP associations remained significant after correcting for multiple comparisons (false discovery rate- FDR. Our findings suggest that genes may be involved in stress fracture pathogenesis. Specifically, the CALCR and the VDR genes are intriguing candidates. The putative involvement of these genes in stress fracture predisposition requires analysis of more cases and controls and sequencing the relevant genomic regions, in order to define the specific gene mutations

  4. Fractal Dimension of Fracture Surface in Rock Material after High Temperature

    Directory of Open Access Journals (Sweden)

    Z. Z. Zhang

    2015-01-01

    Full Text Available Experiments on granite specimens after different high temperature under uniaxial compression were conducted and the fracture surfaces were observed by scanning electron microscope (SEM. The fractal dimensions of the fracture surfaces with increasing temperature were calculated, respectively. The fractal dimension of fracture surface is between 1.44 and 1.63. Its value approximately goes up exponentially with the increase of temperature. There is a quadratic polynomial relationship between the rockburst tendency and fractal dimension of fracture surface; namely, a fractal dimension threshold can be obtained. Below the threshold value, a positive correlativity shows between rockburst tendency and fractal dimension; when the fractal dimension is greater than the threshold value, it shows an inverse correlativity.

  5. Scaling properties of fracture surfaces on glass strengthened by ionic exchange

    International Nuclear Information System (INIS)

    Garza-Mendez, F.J.; Hinojosa-Rivera, M.; Gomez, I.; Sanchez, E.M.

    2007-01-01

    In this work the results of the statistical topometric analysis of fracture surfaces of soda-lime-silica glass with and without ionic exchange treatment are reported. In this case, the mechanism of substitution is K + -Na + . atomic force microscopy (AFM) was employed to record the topometric data from the fracture surface. The roughness exponent (ζ) and the correlation length (ξ) were calculated by the variable bandwidth method. The analysis for both glasses (subjected and non-subjected to ionic exchange) for ζ shows a value ∼0.8, this value agrees well with that reported in the literature for rapid crack propagation in a variety of materials. The correlation length shows different values for each condition. These results, along with those of microhardness indentations suggest that the self-affine correlation length is influenced by the complex interactions of the stress field of microcracks with that resulting from the collective behavior of the point defects introduced by the strengthening mechanism of ionic exchange

  6. Compartmentalization analysis using discrete fracture network models

    Energy Technology Data Exchange (ETDEWEB)

    La Pointe, P.R.; Eiben, T.; Dershowitz, W. [Golder Associates, Redmond, VA (United States); Wadleigh, E. [Marathon Oil Co., Midland, TX (United States)

    1997-08-01

    This paper illustrates how Discrete Fracture Network (DFN) technology can serve as a basis for the calculation of reservoir engineering parameters for the development of fractured reservoirs. It describes the development of quantitative techniques for defining the geometry and volume of structurally controlled compartments. These techniques are based on a combination of stochastic geometry, computational geometry, and graph the theory. The parameters addressed are compartment size, matrix block size and tributary drainage volume. The concept of DFN models is explained and methodologies to compute these parameters are demonstrated.

  7. The surface analysis methods

    International Nuclear Information System (INIS)

    Deville, J.P.

    1998-01-01

    Nowadays, there are a lot of surfaces analysis methods, each having its specificity, its qualities, its constraints (for instance vacuum) and its limits. Expensive in time and in investment, these methods have to be used deliberately. This article appeals to non specialists. It gives some elements of choice according to the studied information, the sensitivity, the use constraints or the answer to a precise question. After having recalled the fundamental principles which govern these analysis methods, based on the interaction between radiations (ultraviolet, X) or particles (ions, electrons) with matter, two methods will be more particularly described: the Auger electron spectroscopy (AES) and x-rays photoemission spectroscopy (ESCA or XPS). Indeed, they are the most widespread methods in laboratories, the easier for use and probably the most productive for the analysis of surface of industrial materials or samples submitted to treatments in aggressive media. (O.M.)

  8. Fracture of nasal bones: an epidemiologic analysis

    Directory of Open Access Journals (Sweden)

    Fornazieri, Marco Aurélio

    2008-12-01

    Full Text Available Introduction: One of the most common diseases in the otorhinolaryngology emergency room is the nasal bones fracture. The peak of incidence is between 15 and 25 years of age. Generally men are more affected. Objective: To analyze the age, gender and the most frequent causes of nasal fractures evaluated in the otorhinolaryngology service of a tertiary hospital. Method: Retrospective study of records of the patients with nasal fracture diagnosis treated between July 1st, 2003 and July 1st, 2007. Results: 167 patients with nasal bones fracture were included in the study, including 134 men and 33 women. Violence was the most frequent cause, with 55 cases (32.9%, followed by fall from their own height, with 33 cases (19.7%, and motorcycle accident, 14 cases (8.4%. The most common age was between 21 and 39 years (46.1%. Conclusion: Male, age between 21 and 39 years and violence are the most common characteristics found in our service. Motorcycle accidents also play an important role in this affection.

  9. Combining periodic hydraulic tests and surface tilt measurements to explore in situ fracture hydromechanics

    Science.gov (United States)

    Schuite, Jonathan; Longuevergne, Laurent; Bour, Olivier; Guihéneuf, Nicolas; Becker, Matthew W.; Cole, Matthew; Burbey, Thomas J.; Lavenant, Nicolas; Boudin, Frédéric

    2017-08-01

    Fractured bedrock reservoirs are of socio-economical importance, as they may be used for storage or retrieval of fluids and energy. In particular, the hydromechanical behavior of fractures needs to be understood as it has implications on flow and governs stability issues (e.g., microseismicity). Laboratory, numerical, or field experiments have brought considerable insights to this topic. Nevertheless, in situ hydromechanical experiments are relatively uncommon, mainly because of technical and instrumental limitations. Here we present the early stage development and validation of a novel approach aiming at capturing the integrated hydromechanical behavior of natural fractures. It combines the use of surface tiltmeters to monitor the deformation associated with the periodic pressurization of fractures at depth in crystalline rocks. Periodic injection and withdrawal advantageously avoids mobilizing or extracting significant amounts of fluid, and it hinders any risk of reservoir failure. The oscillatory perturbation is intended to (1) facilitate the recognition of its signature in tilt measurements and (2) vary the hydraulic penetration depth in order to sample different volumes of the fractured bedrock around the inlet and thereby assess scale effects typical of fractured systems. By stacking tilt signals, we managed to recover small tilt amplitudes associated with pressure-derived fracture deformation. Therewith, we distinguish differences in mechanical properties between the three tested fractures, but we show that tilt amplitudes are weakly dependent on pressure penetration depth. Using an elastic model, we obtain fracture stiffness estimates that are consistent with published data. Our results should encourage further improvement of the method.

  10. Fracture resistance of dental nickel-titanium rotary instruments with novel surface treatment: Thin film metallic glass coating.

    Science.gov (United States)

    Chi, Chih-Wen; Deng, Yu-Lun; Lee, Jyh-Wei; Lin, Chun-Pin

    2017-05-01

    Dental nickel-titanium (NiTi) rotary instruments are widely used in endodontic therapy because they are efficient with a higher success rate. However, an unpredictable fracture of instruments may happen due to the surface characteristics of imperfection (or irregularity). This study assessed whether a novel surface treatment could increase fatigue fracture resistance of dental NiTi rotary instruments. A 200- or 500-nm thick Ti-zirconium-boron (Ti-Zr-B) thin film metallic glass was deposited on ProTaper Universal F2 files using a physical vapor deposition process. The characteristics of coating were analyzed by scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry. In cyclic fatigue tests, the files were performed in a simulated root canal (radius=5 mm, angulation=60°) under a rotating speed of 300rpm. The fatigue fractured cross sections of the files were analyzed with their fractographic performances through scanning electron microscopy images. The amorphous structure of the Ti-Zr-B coating was confirmed by transmission electron microscopy and X-ray diffractometry. The surface of treated files presented smooth morphologies without grinding irregularity. For the 200- and 500-nm surface treatment groups, the coated files exhibited higher resistance of cyclic fatigue than untreated files. In fractographic analysis, treated files showed significantly larger crack-initiation zone; however, no significant differences in the areas of fatigue propagation and catastrophic fracture were found compared to untreated files. The novel surface treatment of Ti-Zr-B thin film metallic glass on dental NiTi rotary files can effectively improve the fatigue fracture resistance by offering a smooth coated surface with amorphous microstructure. Copyright © 2016. Published by Elsevier B.V.

  11. Failure analysis of eleven Gates Glidden drills that fractured intraorally during post space preparation. A retrieval analysis study.

    Science.gov (United States)

    Al Jabbari, Youssef S; Fournelle, Raymond; Al Taweel, Sara M; Zinelis, Spiros

    2017-07-19

    The purpose of this study was to determine the failure mechanism of clinically failed Gates Glidden (GG) drills. Eleven retrieved GG drills (sizes #1 to #3) which fractured during root canal preparation were collected and the fracture location was recorded based on macroscopic observation. All fracture surfaces were investigated by a SEM. Then the fractured parts were embedded in acrylic resin and after metallographic preparation, the microstructure and elemental composition was evaluated by SEM and EDS. The Vickers hardness (HV) of all specimens was also determined. Macroscopic examination and SEM analysis showed that the drills failed near the hand piece end by torsional fatigue with fatigue cracks initiating at several locations around the circumference and propagating toward the center. Final fracture followed by a tensile overloading at the central region of cross section. Microstructural analysis, hardness measurements and EDS show that the drills are made of a martensitic stainless steel like AISI 440C. Based on the findings of this study, clinicians should expect fatigue fracture of GG drills that have small size during root canal preparation. Selection of a more fatigue resistant stainless steel alloy and enhancing the instrument design might reduce the incidence of quasi-cleavage fracture on GG drills.

  12. Fractures of the mandible and maxilla: A 10-year analysis

    Directory of Open Access Journals (Sweden)

    Estie Kruger

    2016-01-01

    Full Text Available Background Previous analysis of jaw fracture hospitalisations in Western Australia (WA indicated disproportionately high rates of hospitalisations for Aboriginal people. This study was to follow-up on the earlier analysis to determine if inequalities in terms of jaw fracture hospitalisation rates between Aboriginal and non-Aboriginal people have changed. Aims This study, done over a 10-year period from 1999/2000 to 2008/2009, aimed to determine rates of hospitalisations for jaw fractures in WA, trends over the 10–year period, and direct costs associated with these hospital admissions. Methods Hospitalisation data were obtained from the Western Australian Hospital Morbidity Data System (HMDS. Episodes were selected on the basis of an ICD10-AM code being S02.4 (Fracture of the malar and maxillary bones and S02.6 (Fracture of the mandible. Self-reported Aboriginality were used to compare Aboriginal to non-Aboriginal populations. Estimated cost of care was determined for each episode using the national standard diagnostic-related group (DRG average price. Results Our findings indicate that inequalities between Aboriginal and non-Aboriginal people in terms of hospital admissions for jaw fractures exist in WA, and continued over a decade-long period. Higher fracture rates occurred amongst males, Aboriginal people, younger adult age-groups, those from low socioeconomic areas, and those from remote and very remote areas. The DRG cost per person for jaw fractures ranged between AUD $842 and $109,002, with a median cost of $4,965. Conclusion Hospital admission rates for the treatment of maxillary and mandibular fractures is very strongly divided along racial and socioeconomic lines in WA.

  13. Surface self-potential patterns related to transmissive fracture trends during a water injection test

    Science.gov (United States)

    DesRoches, A. J.; Butler, K. E.; MacQuarrie, K. TB

    2018-03-01

    Variations in self-potential (SP) signals were recorded over an electrode array during a constant head injection test in a fractured bedrock aquifer. Water was injected into a 2.2 m interval isolated between two inflatable packers at 44 m depth in a vertical well. Negative SP responses were recorded on surface corresponding to the start of the injection period with strongest magnitudes recorded in electrodes nearest the well. SP response decreased in magnitude at electrodes further from the well. Deflation of the packer system resulted in a strong reversal in the SP signal. Anomalous SP patterns observed at surface at steady state were found to be aligned with dominant fracture strike orientations found within the test interval. Numerical modelling of fluid and current flow within a simplified fracture network showed that azimuthal patterns in SP are mainly controlled by transmissive fracture orientations. The strongest SP gradients occur parallel to hydraulic gradients associated with water flowing out of the transmissive fractures into the tighter matrix and other less permeable cross-cutting fractures. Sensitivity studies indicate that increasing fracture frequency near the well increases the SP magnitude and enhances the SP anomaly parallel to the transmissive set. Decreasing the length of the transmissive fractures leads to more fluid flow into the matrix and into cross-cutting fractures proximal to the well, resulting in a more circular and higher magnitude SP anomaly. Results from the field experiment and modelling provide evidence that surface-based SP monitoring during constant head injection tests has the ability to identify groundwater flow pathways within a fractured bedrock aquifer.

  14. A numerical procedure for transient free surface seepage through fracture networks

    Science.gov (United States)

    Jiang, Qinghui; Ye, Zuyang; Zhou, Chuangbing

    2014-11-01

    A parabolic variational inequality (PVI) formulation is presented for the transient free surface seepage problem defined for a whole fracture network. Because the seepage faces are specified as Signorini-type conditions, the PVI formulation can effectively eliminate the singularity of spillpoints that evolve with time. By introducing a continuous penalty function to replace the original Heaviside function, a finite element procedure based on the PVI formulation is developed to predict the transient free surface response in the fracture network. The effects of the penalty parameter on the solution precision are analyzed. A relative error formula for evaluating the flow losses at steady state caused by the penalty parameter is obtained. To validate the proposed method, three typical examples are solved. The solutions for the first example are compared with the experimental results. The results from the last two examples further demonstrate that the orientation, extent and density of fractures significantly affect the free surface seepage behavior in the fracture network.

  15. Quantitative x-ray fractographic analysis of fatigue fractures

    International Nuclear Information System (INIS)

    Saprykin, Yu.V.

    1983-01-01

    The study deals with quantitative X-ray fractographic investigation of fatigue fractures of samples with sharp notches tested at various stresses and temperatures with the purpose of establishing a connection between material crack resistance parameters and local plastic instability zones restraining and controlling the crack growth. At fatigue fractures of notched Kh18N9T steel samples tested at +20 and -196 deg C a zone of sharp ring notch effect being analogous to the zone in which crack growth rate is controlled by the microshifting mechanisms is singled out. The size of the notched effect zone in the investigate steel is unambiguosly bound to to the stress amplitude. This provides the possibility to determine the stress value by the results of quantitative fractographic analysis of notched sample fractures. A possibility of determining one of the threshold values of cyclic material fracture toughness by the results of fatigue testing and fractography of notched sample fractures is shown. Correlation between the size of the hsub(s) crack effect zone in the notched sample, delta material yield limit and characteristic of cyclic Ksub(s) fracture toughness has been found. Such correlation widens the possibilities of quantitative diagnostics of fractures by the methods of X-ray fractography

  16. Fatigue fracture analysis in medium carbon structural steel and austenitic stainless steel by X-ray fractography

    International Nuclear Information System (INIS)

    Rao, N.N.; Azmi bin Rahmat

    1994-01-01

    Apart from the reidual stresses present in the bulk material, a growing fatigue crack may develop its own stress field ahead of the crack tip which in turn could influence the crack propagation behaviour. A fracture surface analysis through measurement of the residual stress of a failed component may provide some additional useful information to that obtained through conventional metallurgical and fracture mechanics investigations. This method of fracture surface analysis using x-ray diffraction technique is known as X -ray Fractography . Residual stress (ρ sub γ) and the full width at half maximum (FWHM) of the x-ray diffraction profile of any reflection are determined at different crack lengths on the fracture surface. These are then corelated to the fracture toughness parameters such as fracture toughness K sub I sub C, the maximum stress intensity factor K sub max and the stress intensity factor range δK. The present investigation aims at detailed x-ray analysis of the fatigue fractured surfaces of the compact tension specimens prepared from ferritic and austenitic stainless steels. The ferritic steel has been subjected to various heat treatments to obtain different microstructures and mechanical properties. The overall observations are analyzed through fatigue (cumulative) damage and material science concepts

  17. Imaging of acute injuries of the articular surfaces (chondral, osteochondral and subchondral fractures)

    Energy Technology Data Exchange (ETDEWEB)

    Bohndorf, K. [Department of Radiology, Zentralklinikum Augsburg (Germany)

    1999-10-01

    Fractures involving the articulating surfaces of bone are a common cause of chronic disability after joint injury. Acute fractures of the articular surface typically run parallel to the surface and are confined to the cartilage and/or the immediate subchondral cancellous bone. They should be distinguished from vertical or oblique bone fractures with intra-articular extension. This article reviews the mechanism of acute articular surface injuries, as well as their incidence, clinical presentation, radiologic appearance and treatment. A classification is presented based on direct inspection (arthroscopy) and imaging (especially MRI), emphasizing the distinction between lesions with intact (subchondral impaction and subchondral bone bruises) and disrupted (chondral, osteochondral lesions) cartilage. Hyaline cartilage, subchondral bone plate and subchondral cancellous bone are to be considered an anatomic unit. Subchondral articular surface lesions, osteochondral fractures and solely chondral fractures are different manifestations of impaction injuries that affect the articulating surface. Of the noninvasive imaging modalities, conventional radiography and MRI provide the most relevant information. The appropriate use of short tau inversion recovery, T1-weighted and T2-weighted (turbo) spin-echo as well as gradient-echo sequences, enables MRI to classify the various acute articular surface lesions with great accuracy and provides therapeutic guidance. (orig.)

  18. Imaging of acute injuries of the articular surfaces (chondral, osteochondral and subchondral fractures)

    International Nuclear Information System (INIS)

    Bohndorf, K.

    1999-01-01

    Fractures involving the articulating surfaces of bone are a common cause of chronic disability after joint injury. Acute fractures of the articular surface typically run parallel to the surface and are confined to the cartilage and/or the immediate subchondral cancellous bone. They should be distinguished from vertical or oblique bone fractures with intra-articular extension. This article reviews the mechanism of acute articular surface injuries, as well as their incidence, clinical presentation, radiologic appearance and treatment. A classification is presented based on direct inspection (arthroscopy) and imaging (especially MRI), emphasizing the distinction between lesions with intact (subchondral impaction and subchondral bone bruises) and disrupted (chondral, osteochondral lesions) cartilage. Hyaline cartilage, subchondral bone plate and subchondral cancellous bone are to be considered an anatomic unit. Subchondral articular surface lesions, osteochondral fractures and solely chondral fractures are different manifestations of impaction injuries that affect the articulating surface. Of the noninvasive imaging modalities, conventional radiography and MRI provide the most relevant information. The appropriate use of short tau inversion recovery, T1-weighted and T2-weighted (turbo) spin-echo as well as gradient-echo sequences, enables MRI to classify the various acute articular surface lesions with great accuracy and provides therapeutic guidance. (orig.)

  19. Odontoid fractures: A retrospective analysis of 53 cases

    Directory of Open Access Journals (Sweden)

    Shetty Arjun

    2009-01-01

    Full Text Available Background: The management of odontoid fracture has evolved but controversy persists as to the best method for Type II odontoid fractures with or without atlantoaxial (AA instability. The anterior odontoid screw fixation can be associated with significant morbidity while delayed odontoid screw fixation has shown to be associated with reasonable good fusion rates. We conducted a retrospective analysis to evaluate the outcome of a trial of conservative management in type II odontoid fractures without atlantoaxial instability (Group A followed by delayed odontoid screw fixation in cases in which fusion was not achieved by conservative treatment. The outcome of type II odontoid fracture with AA subluxation (Group B was also analysed where closed reduction on traction could be achieved and in those atlantoaxial subluxations that were irreducible an intraoperative reduction was done. Materials and Methods: A retrospective evaluation of 53 cases of odontoid fractures treated over a 9-year period is being reported. All odontoid fractures without AA instability (n=29 were initially managed conservatively. Three patients who did not achieve union with conservative management were treated with delayed anterior screw fixation. Twenty-four cases of odontoid fractures were associated with AA instability; 17 of them could be reduced with skeletal traction and were managed with posterior fusion and fixation. Of the seven cases that were irreducible, the initial three cases were treated by odontoid excision followed by posterior fusion and fixation; however, in the later four cases, intra operative reduction was achieved by a manipulation procedure, and posterior fusion and fixation was performed. Results: Twenty-six of 29 cases of odontoid fracture without AA instability achieved fracture union with conservative management whereas the remaining three patients achieved union following delayed anterior odontoid screw fixation. 17 out of 24 odontoid fracture with

  20. Three-dimensional reconstruction of fracture surfaces of CFRP type composite materials

    International Nuclear Information System (INIS)

    Lobo, Raquel de Moraes

    2009-01-01

    The three-dimensional reconstruction of fracture surfaces of CFRP type composite materials is presented in this work as a possible method for the fractographic analysis of this material, whose rupture surface can present an accentuated roughness, with great variation in height. Two methods are presented for this purpose: the reconstruction for variable focus, carried through with images of optic microscopy and the reconstruction for parallax, carried through with pair of stereo images, obtained by means of scanning electronic microscopy. An evaluation is carried through for each one of the two methods, having argued its limits and the efficiency of each one of them, before the difficulties of analysis of unidirectional and multidirectional composite materials. The method of variable focus presented an excellent reconstruction result, but it has the need of a great number of images, spent time of the instrument and magnifying limit of the images as factors to be considered in the choice of better method. The tilting of the specimen, during the parallax method, discloses alterations in the histograms of the images acquired in the clockwise direction that limit the use of the method for materials with high roughness. The acquiring of images in only one direction and the construction of a region of interest, located in the center of the image are suggestions to turn the method most including. The linearity of the projections of features in the inclined image also suggests the possibility to carry through the reconstruction using, instead of only two, multiple images gotten in the counter-clockwise direction. The alterations proposals to modify the routine, are suggested so that the program can be applied in a more comprehensive form, independent of the quality of the observed fracture surface. (author)

  1. Diagnostic value of 3 D CT surface reconstruction in spinal fractures

    Energy Technology Data Exchange (ETDEWEB)

    Koesling, S. [Department of Radiology, Univ. of Leipzig (Germany); Dietrich, K. [Department of Radiology, Univ. of Leipzig (Germany); Steinecke, R. [Department of Radiology, Univ. of Leipzig (Germany); Kloeppel, R. [Department of Radiology, Univ. of Leipzig (Germany); Schulz, H.G. [Department of Radiology, Univ. of Leipzig (Germany)

    1997-02-01

    Our purpose was to evaluate the diagnostic value of three-dimensional (3 D) CT surface reconstruction in spinal fractures in comparison with axial and reformatted images. A total of 50 patients with different CT-proven spinal fractures were analysed retrospectively. Based on axial scans and reformatted images, the spinal fractures were classified according to several classifications as Magerl for the thoraco-lumbar and lower cervical spine by one radiologist. Another radiologist performed 3 D CT surface reconstructions with the aim of characterizing the different types of spinal fractures. A third radiologist classified the 3 D CT surface reconstruction according to the Magerl classification. The results of the blinded reading process were compared. It was checked to see in which type and subgroup 3 D surface reconstructions were helpful. Readers one and two obtained the same results in the classification. The 3 D surface reconstruction did not yield any additional diagnostic information concerning type A and B injuries. Indeed, the full extent of the fracture could be easier recognized with axial and reformatted images in all cases. In 10 cases of C injuries, the dislocation of parts of vertebrae could be better recognized with the help of 3 D reconstructions. A 3 D CT surface reconstruction is only useful in rotational and shear vertebral injuries (Magerl type C injury). (orig.). With 4 figs., 1 tab.

  2. Fracture behaviour of a magnesium–aluminium alloy treated by selective laser surface melting treatment

    International Nuclear Information System (INIS)

    Taltavull, C.; López, A.J.; Torres, B.; Rams, J.

    2014-01-01

    Highlights: • β-Mg 17 Al 12 presents fragile fracture behavior decreasing the ductility of AZ91D. • SLSM treatment only modifies the β-Mg 17 Al 12 phase whilst α-Mg remains unaltered. • In-situ SEM bending test allows to observe and data record of the crack propagation. • Eutectic microestructure of modified β-phase presents ductile fracture behaviour. • Fracture toughness of laser treated specimen is 40% greater than as-received alloy. - Abstract: Fracture behaviour of AZ91D magnesium alloy is dominated by the brittle fracture of the β-Mg 17 Al 12 phase so its modification is required to improve the toughness of this alloy. The novel laser treatment named as Selective Laser Surface Melting (SLSM) is characterized by the microstructural modification of the β-Mg 17 Al 12 phase without altering the α-Mg matrix. We have studied the effect of the selected microstructural modification induced by the laser treatment in the fracture behaviour of the alloy has been studied using in situ Scanning Electron Microscopy bending test. This test configuration allows the in situ observation of the crack progression and the record of the load–displacement curve. It has been observed that the microstructural modification introduced by SLSM causes an increase of 40% of the fracture toughness of the treated specimen. This phenomenon can be related with the transition from brittle to ductile fracture behaviour of the laser modified β-phase

  3. New model for surface fracture induced by dynamical stress

    OpenAIRE

    Andersen, J. V.; Lewis, L. J.

    1997-01-01

    We introduce a model where an isotropic, dynamically-imposed stress induces fracture in a thin film. Using molecular dynamics simulations, we study how the integrated fragment distribution function depends on the rate of change and magnitude of the imposed stress, as well as on temperature. A mean-field argument shows that the system becomes unstable for a critical value of the stress. We find a striking invariance of the distribution of fragments for fixed ratio of temperature and rate of ch...

  4. Effect of implantoplasty on fracture resistance and surface roughness of standard diameter dental implants.

    Science.gov (United States)

    Costa-Berenguer, Xavier; García-García, Marta; Sánchez-Torres, Alba; Sanz-Alonso, Mariano; Figueiredo, Rui; Valmaseda-Castellón, Eduard

    2018-01-01

    To assess the effect of implantoplasty on the fracture resistance, surface roughness, and macroscopic morphology of standard diameter (4.1 mm) external connection dental implants. An in vitro study was conducted in 20 screw-shaped titanium dental implants with an external connection. In 10 implants, the threads and surface were removed and polished with high-speed burs (implantoplasty), while the remaining 10 implants were used as controls. The final implant dimensions were recorded. The newly polished surface quality was assessed by scanning electron microscopy (SEM) and by 3D surface roughness analysis using a confocal laser microscope. Finally, all the implants were subjected to a mechanical pressure resistance test. A descriptive analysis of the data was made. Also, Student's t tests were employed to detect differences regarding the compression tests. Implantoplasty was carried out for a mean time of 10 min and 48 s (standard deviation (SD) of 1 min 22 s). Macroscopically, the resulting surface had a smooth appearance, although small titanium shavings and silicon debris were present. The final surface roughness (S a values 0.1 ± 0.02 μm) was significantly lower than that of the original (0.75 ± 0.08 μm S a ) (p = .005). There was minimal reduction in the implant's inner body diameter (0.19 ± 0.03 mm), and no statistically significant differences were found between the test and control implants regarding the maximum resistance force (896 vs 880 N, respectively). Implantoplasty, although technically demanding and time-consuming, does not seem to significantly alter fracture resistance of standard diameter external connection implants. A smooth surface with S a values below 0.1 μm can be obtained through the use of silicon polishers. A larger sample is required to confirm that implantoplasty does not significantly affect the maximum resistance force of standard diameter external connection implants. © 2017 John Wiley & Sons A/S. Published

  5. The morphologies of fractured surfaces and fracture toughness in some As-Se-Sb-S-I glasses

    International Nuclear Information System (INIS)

    Lukic, S.R.; Petrovic, D.M.; Skuban, F.; Sidanin, L.; Guth, I.O.

    2006-01-01

    As part of a general physical characterization of amorphous materials in the pseudobinary system (As 2 Se 3 ) 100-x (SbSI) x type, their indentation fracture toughness was determined. It is a system with the variable ratio of classical amorphous compound As 2 Se 3 and the molecule of antimony sulfoiodide, SbSI, which in the monocrystal form is characterized as ferroelectrics. Because of chalcogenides are generally very brittle and under load they crack very easily, these glasses have been studied with the aim of examining the possibility of obtaining some new structures on the basis of the materials with amorphous internal network, the structures that will have a higher quality in respect of mechanical properties. The morphologies of fractured surfaces were investigated by scanning electron microscope

  6. The morphologies of fractured surfaces and fracture toughness in some As-Se-Sb-S-I glasses

    Energy Technology Data Exchange (ETDEWEB)

    Lukic, S.R. [Department of Physics, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 4, 21000 Novi Sad (Serbia and Montenegro)]. E-mail: svetdrag@im.ns.ac.yu; Petrovic, D.M. [Department of Physics, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 4, 21000 Novi Sad (Serbia and Montenegro); Skuban, F. [Department of Physics, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 4, 21000 Novi Sad (Serbia and Montenegro); Sidanin, L. [Department for Production Engineering, Faculty of Technical Sciences, University of Novi Sad, Trg D. Obradovica 6, 21000 Novi Sad (Serbia and Montenegro); Guth, I.O. [Department of Physics, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 4, 21000 Novi Sad (Serbia and Montenegro)

    2006-09-15

    As part of a general physical characterization of amorphous materials in the pseudobinary system (As{sub 2}Se{sub 3}){sub 100-x}(SbSI) {sub x} type, their indentation fracture toughness was determined. It is a system with the variable ratio of classical amorphous compound As{sub 2}Se{sub 3} and the molecule of antimony sulfoiodide, SbSI, which in the monocrystal form is characterized as ferroelectrics. Because of chalcogenides are generally very brittle and under load they crack very easily, these glasses have been studied with the aim of examining the possibility of obtaining some new structures on the basis of the materials with amorphous internal network, the structures that will have a higher quality in respect of mechanical properties. The morphologies of fractured surfaces were investigated by scanning electron microscope.

  7. Fracture analysis of concrete gravity dam under earthquake induced ...

    African Journals Online (AJOL)

    Michael Horsfall

    Fracture analysis of concrete gravity dam under earthquake induced loads. 1. ABBAS MANSOURI;. 2 ... 1 Civil Engineering, Islamic Azad University (South Branch of Tehran)Tehran, Iran ..... parameter has on the results of numerical calculations. In this analysis ... with the help of Abaqus software (Abaqus theory manual ...

  8. Analysis of thin fractures with GPR: from theory to practice

    Science.gov (United States)

    Arosio, Diego; Zanzi, Luigi; Longoni, Laura; Papini, Monica

    2017-04-01

    Whenever we perform a GPR survey to investigate a rocky medium, being the ultimate purpose of the survey either to study the stability of a rock slope or to determine the soundness of a quarried rock block, we would like mainly to detect any fracture within the investigated medium and, possibly, to estimate the parameters of the fractures, namely thickness and filling material. In most of the practical cases, rock fracture thicknesses are very small when compared to the wavelength of the electromagnetic radiation generated by the GPR systems. In such cases, fractures are to be considered as thin beds, i.e. two interfaces whose distance is smaller than GPR resolving capability, and the reflected signal is the sum of the electromagnetic reverberation within the bed. According to this, fracture parameters are encoded in the thin bed complex response and in this work we propose a methodology based on deterministic deconvolution to process amplitude and phase information in the frequency domain to estimate fracture parameters. We first present some theoretical aspects related to thin bed response and a sensitivity analysis concerning fracture thickness and filling. Secondly, we deal with GPR datasets collected both during laboratory experiments and in the facilities of quarrying activities. In the lab tests fractures were simulated by placing materials with known electromagnetic parameters and controlled thickness in between two small marble blocks, whereas field GPR surveys were performed on bigger quarried ornamental stone blocks before they were submitted to the cutting process. We show that, with basic pre-processing and the choice of a proper deconvolving signal, results are encouraging although an ambiguity between thickness and filling estimates exists when no a-priori information is available. Results can be improved by performing CMP radar surveys that are able to provide additional information (i.e., variation of thin bed response versus offset) at the expense

  9. Two- and three-dimensional CT analysis of ankle fractures

    International Nuclear Information System (INIS)

    Magid, D.; Fishman, E.K.; Ney, D.R.; Kuhlman, J.E.

    1988-01-01

    CT with coronal and sagittal reformatting (two-dimensional CT) and animated volumetric image rendering (three-dimensional CT) was used to assess ankle fractures. Partial volume limits transaxial CT in assessments of horizontally oriented structures. Two-dimensional CT, being orthogonal to the plafond, superior mortise, talar dome, and tibial epiphysis, often provides the most clinically useful images. Two-dimensional CT is most useful in characterizing potentially confusing fractures, such as Tillaux (anterior tubercle), triplane, osteochondral talar dome, or nondisplaced talar neck fractures, and it is the best study to confirm intraarticular fragments. Two-and three-dimensional CT best indicate the percentage of articular surface involvement and best demonstrate postoperative results or complications (hardware migration, residual step-off, delayed union, DJD, AVN, etc). Animated three-dimensional images are the preferred means of integrating the two-dimensional findings for surgical planning, as these images more closely simulate the clinical problem

  10. A demographic analysis of vertical root fractures.

    Science.gov (United States)

    Cohen, Stephen; Berman, Louis H; Blanco, Lucia; Bakland, Leif; Kim, Jay S

    2006-12-01

    Teeth with vertical root fractures (VRFs) have complete or incomplete fractures that extends through the enamel, dentin and pulp, down the long axis of the tooth. Several different variables were investigated and statistically evaluated as to their correlation with the presence of VRFs. Specifically analyzed were gender, tooth location, age, radiographic and clinical findings, bruxism, and pulpal status. The data were collected from three different endodontists, from three different geographic locations, comprising a total of 227 teeth. Although VRFs may occur in conjunction with any of the parameters investigated, only certain factors were found to occur in a significant number of cases. The results indicate that VRFs are statistically more prevalent in mandibular molars and maxillary premolars. They are associated with periradicular bone loss, pain to percussion, extensive restorations, and seem to occur more often in females and older patients. However, VRFs are not necessarily related to periapical bone loss, a widening of the periodontal ligament space, associated periodontal pockets, a sinus tract, particular pulpal status, or bruxism.

  11. Probabilistic fracture mechanics analysis of reactor vessels with low upper-shelf fracture toughness

    International Nuclear Information System (INIS)

    Yoon, K.K.

    1993-01-01

    A class of submerged-arc welds used in fabricating early reactor vessels has relatively high copper contents. Studies have shown that when such vessels are irradiated, the copper contributes to lowering the Charpy upper-shelf energy level. To address this concern, 10CFR50, Appendix G requires a fracture mechanics analysis to demonstrate an adequate margin of safety for continued service. The B and W Owners Group (B and WOG) has been accumulating J-resistance fracture toughness data for these weld metals. Based on a mathematical model derived from this B and WOG data base, the first Appendix G analysis was performed. Another important issue affecting reactor vessel integrity is pressurized thermal shock (PIS) transients. In the early 1980s, probabilistic fracture mechanics analyses were performed on a reactor vessel to determine the probability of failure under postulated accident scenarios. Results of such analyses were used by the Nuclear Regulatory Commission (NRC) to establish the screening criteria for assessing reactor vessel integrity under PTS transient loads. This paper addresses the effect of low upper-shelf toughness on the probability of failure of reactor vessels under PTS loads. Probabilistic fracture mechanics codes were modified to include the low upper-shelf toughness model used in a reference and a series of analyses was performed using plant-specific material conditions and realistic PTS scenarios. The results indicate that low upper-shelf toughness has an insignificant effect on the probability of reactor vessel failures. This is mostly due to PTS transients being susceptible to crack initiation at low temperatures and not affected by upper-shelf fracture toughness

  12. Viscosity and surface tension effects during multiphase flow in propped fractures

    Science.gov (United States)

    Dzikowski, Michał; Dąbrowski, Marcin

    2017-04-01

    Geological sequestration of CO2 was proposed as an important mechanism to reduce its emission into atmosphere. CO2 exhibits a higher affinity to organic matter than methane molecules and, potentially, it could be pumped and stored in shale reservoirs while enhancing late stage shale gas production. A successful analysis of CO2 sequestration in low matrix permeability rocks such as shales requires a thorough understanding of multiphase flow in stimulated rock fractures, which provide most significant pathways for fluids in such systems. Multiphase fracture flows are also of great relevance to brine, oil and gas migration in petroleum systems, water and stream circulation in geothermal reservoirs, and chemical transport of non-aqueous phase liquids in shallow hydrogeological systems, particularly in partially saturated zones. There are various physical models that describe phenomena taking place during multiphase flow through porous media. One of key aspects that need to be considered are pore-scale effects related to capillarity. Unfortunately, detailed models that describe motion and evolution of phase or component boundary require direct numerical simulations and spatial resolutions that are hard to reach when considering industrial relevant systems. Main aim of the presented work was the development of reduced 2.5D models based on Brinkman approximation of thin domain flow that would be able to capture local scale phenomena without expensive 3D simulations. Presented approach was designed specifically to tackle incompressible and immiscible systems and is based on Continuous Surface Force approach presented by Brackbill et al., implemented using Lattice Boltzmann Method. Presented approach where firstly validated against standard test cases with known classical solution and known experimental data. In the second part, we present and discuss two component, immiscible permeability data for rough and propped fracture obtained with our code for a rage of proppants

  13. Influence of material ductility and crack surface roughness on fracture instability

    International Nuclear Information System (INIS)

    Khezrzadeh, Hamed; Wnuk, Michael P; Yavari, Arash

    2011-01-01

    This paper presents a stability analysis for fractal cracks. First, the Westergaard stress functions are proposed for semi-infinite and finite smooth cracks embedded in the stress fields associated with the corresponding self-affine fractal cracks. These new stress functions satisfy all the required boundary conditions and according to Wnuk and Yavari's (2003 Eng. Fract. Mech. 70 1659-74) embedded crack model they are used to derive the stress and displacement fields generated around a fractal crack. These results are then used in conjunction with the final stretch criterion to study the quasi-static stable crack extension, which in ductile materials precedes the global failure. The material resistance curves are determined by solving certain nonlinear differential equations and then employed in predicting the stress levels at the onset of stable crack growth and at the critical point, where a transition to the catastrophic failure occurs. It is shown that the incorporation of the fractal geometry into the crack model, i.e. accounting for the roughness of the crack surfaces, results in (1) higher threshold levels of the material resistance to crack propagation and (2) higher levels of the critical stresses associated with the onset of catastrophic fracture. While the process of quasi-static stable crack growth (SCG) is viewed as a sequence of local instability states, the terminal instability attained at the end of this process is identified with the global instability. The phenomenon of SCG can be used as an early warning sign in fracture detection and prevention.

  14. Intra-articualr calcaneal fractures: Computed tomographic analysis

    International Nuclear Information System (INIS)

    Rosenberg, Z.S.; Feldman, F.; Singson, R.D.

    1987-01-01

    Computed tomography (CT) analysis of 21 intra-articular calcaneal fractures categorized according to the Essex-Lopresti classification revealed the following distribution: joint depression-type 57%, comminuted type 43%, tongue-type 0%. The posterior calcaneal facet was fractured and/or depressed in 100% of the cases while the medial facet was involved in only 25% of the cases. CT proved superior to plain films by consistently demonstrating additional fracture components within each major category suggesting subclassifications which have potential prognostic value. CT allowed more expeditious handling of acutely injured patients, and improved preoperative planning, postoperative follow-up, and detailed analysis of causes for chronic residual pain. CT further identified significant soft tissue injuries such as peroneal tendon displacement which cannot be delineated on plain films. (orig.)

  15. Fracture Behavior of High-Nitrogen Austenitic Stainless Steel Under Continuous Cooling: Physical Simulation of Free-Surface Cracking of Heavy Forgings

    Science.gov (United States)

    Wang, Zhenhua; Xue, Hongpeng; Fu, Wantang

    2018-03-01

    18Mn18Cr0.6N steel was tension tested at 0.001 s-1 to fracture from 1473 K to 1363 K (1200 °C to 1090 °C, fracture temperature) at a cooling rate of 0.4 Ks-1. For comparison, specimens were tension tested at temperatures of 1473 K and 1363 K (1200 °C and 1090 °C). The microstructure near the fracture surface was examined using electron backscatter diffraction analysis. The lowest hot ductility was observed under continuous cooling and was attributed to the suppression of dynamic recrystallization nucleation.

  16. Monitoring massive fracture growth at 2-km depths using surface tiltmeter arrays

    Science.gov (United States)

    Wood, M.D.

    1979-01-01

    Tilt due to massive hydraulic fractures induced in sedimentary rocks at depths of up to 2.2 km have been recorded by surface tiltmeters. Injection of fluid volumes up to 4 ?? 105 liters and masses of propping agent up to 5 ?? 105 kg is designed to produce fractures approximately 1 km long, 50-100 m high and about 1 cm wide. The surface tilt data adequately fit a dislocation model of a tensional fault in a half-space. Theoretical and observational results indicate that maximum tilt occurs at a distance off the strike of the fracture equivalent to 0.4 of the depth to the fracture. Azimuth and extent of the fracture deduced from the geometry of the tilt field agree with other kinds of geophysical measurements. Detailed correlation of the tilt signatures with pumping parameters (pressure, rate, volume, mass) have provided details on asymmetry in geometry and growth rate. Whereas amplitude variations in tilt vary inversely with the square of the depth, changes in flow rate or pressure gradient can produce a cubic change in width. These studies offer a large-scale experimental approach to the study of problems involving fracturing, mass transport, and dilatancy processes. ?? 1979.

  17. Mechanical test and fractal analysis on anisotropic fracture of cortical bone

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Dagang [State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044 (China); College of Aerospace Engineering, Chongqing University, Chongqing 400044 (China); Chen, Bin, E-mail: bchen@cqu.edu.cn [State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044 (China); College of Aerospace Engineering, Chongqing University, Chongqing 400044 (China); Ye, Wei [College of Aerospace Engineering, Chongqing University, Chongqing 400044 (China); Gou, Jihua [Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL 32816 (United States); Fan, Jinghong [Division of Mechanical Engineering, Alfred University, Alfred, NY 14802 (United States)

    2015-12-01

    Highlights: • The mechanical properties of the cortical bone of fresh bovine femora along three different directions are tested through four-point bending experiments. • SEM observation shows that the roughness of the fracture surfaces of the three different directions of the bone are remarkably different. • The fractal dimensions of the different fracture surfaces of the bone are calculated by box-counting method in MATLAB. • The fracture energies of the different fracture directions are calculated based on their fractal models. - Abstract: The mechanical properties of the cortical bone of fresh bovine femora along three different directions are tested through four-point bending experiments. It is indicated that the fracture energy along the transversal direction of the bone is distinctly larger than those of the longitudinal and radial directions. The fracture surfaces of the three different directions are observed by scanning electron microscope (SEM). It is shown that the roughness of the fracture surface of the transversal direction is obviously larger than those of the fracture surfaces of the longitudinal and radial directions. It is also revealed that the osteons in the bone are perpendicular to the fracture surface of the transversal direction and parallel to the fracture surfaces of the longitudinal and radial directions. Based on these experimental results, the fractal dimensions of the fracture surfaces of different directions are calculated by box-counting method in MATLAB. The calculated results show that the fractal dimension of the fracture surface of the transversal direction is remarkably larger than those of the fracture surfaces of the longitudinal and radial directions. The fracture energies of different directions are also calculated based on their fractal models. It is denoted that the fracture energy of the transversal direction is remarkably larger than those of the longitudinal and radial directions. The calculated results are in

  18. Mechanical test and fractal analysis on anisotropic fracture of cortical bone

    International Nuclear Information System (INIS)

    Yin, Dagang; Chen, Bin; Ye, Wei; Gou, Jihua; Fan, Jinghong

    2015-01-01

    Highlights: • The mechanical properties of the cortical bone of fresh bovine femora along three different directions are tested through four-point bending experiments. • SEM observation shows that the roughness of the fracture surfaces of the three different directions of the bone are remarkably different. • The fractal dimensions of the different fracture surfaces of the bone are calculated by box-counting method in MATLAB. • The fracture energies of the different fracture directions are calculated based on their fractal models. - Abstract: The mechanical properties of the cortical bone of fresh bovine femora along three different directions are tested through four-point bending experiments. It is indicated that the fracture energy along the transversal direction of the bone is distinctly larger than those of the longitudinal and radial directions. The fracture surfaces of the three different directions are observed by scanning electron microscope (SEM). It is shown that the roughness of the fracture surface of the transversal direction is obviously larger than those of the fracture surfaces of the longitudinal and radial directions. It is also revealed that the osteons in the bone are perpendicular to the fracture surface of the transversal direction and parallel to the fracture surfaces of the longitudinal and radial directions. Based on these experimental results, the fractal dimensions of the fracture surfaces of different directions are calculated by box-counting method in MATLAB. The calculated results show that the fractal dimension of the fracture surface of the transversal direction is remarkably larger than those of the fracture surfaces of the longitudinal and radial directions. The fracture energies of different directions are also calculated based on their fractal models. It is denoted that the fracture energy of the transversal direction is remarkably larger than those of the longitudinal and radial directions. The calculated results are in

  19. A study on the ductile fracture of a surface crack, 1

    International Nuclear Information System (INIS)

    Kikuchi, Masanori; Nishio, Tamaki; Yano, Kazunori; Machida, Kenji; Miyamoto, Hiroshi

    1988-01-01

    Ductile fracture of surface crack is studied experimentally and numerically. At first, fatigue pre-crack is introduced, and the aspect ratios of the growing fatigue crack are measured. Then the ductile fracture test is carried out and the distributions of SZW and Δa are measured. It is noted that Δa is largest where φ, the angle from surface, is nearly 30deg. J integral distribution is evaluated by the finite element method, and it is shown that the J value is also the largest where φ is nearly 30deg. (author)

  20. Reliability Analysis of Fatigue Fracture of Wind Turbine Drivetrain Components

    DEFF Research Database (Denmark)

    Berzonskis, Arvydas; Sørensen, John Dalsgaard

    2016-01-01

    in the volume of the casted ductile iron main shaft, on the reliability of the component. The probabilistic reliability analysis conducted is based on fracture mechanics models. Additionally, the utilization of the probabilistic reliability for operation and maintenance planning and quality control is discussed....

  1. X-ray fractography on fatigue fracture surface of high manganese austenitic steel

    International Nuclear Information System (INIS)

    Akita, Koichi; Misawa, Hiroshi; Kodama, Shotaro; Saito, Tetsuro.

    1997-01-01

    Fatigue tests were carried out under constant stress amplitude, using a non-magnetic high manganese Mn-Cr steel. X-ray fractography was applied on the fatigue fractured surface to investigate the relationship between stress intensity factor and residual stress or half-value breadth of the X-ray diffraction profile. The fatigue crack propagation rate of this non-magnetic Mn-Cr steel had the same tendency as in the ordinary structural ferritic steels. The relationship between stress intensity factor and the residual stress or half-value breadth of the steel was almost the same as that of the ferritic cyclic work hardening steels. No stress induced transformation was observed on the fracture surface, but the residual stress on the fractured surface was compressive in the high stress intensity factors range, which is typical in the cyclic work hardening steels. The half-value breadth on the fractured surface increased with increasing effective stress intensity factor range. The relationship between the half-value breadth and stress intensity factor range was represented by a linear line regardless of the stress ratio. Therefore, the acting stress intensity factor range at the time of fracture can be estimated from the half-value breadth. The depth of monotonic plastic zone was estimated from the distribution of half-value breadth beneath the fractured surface. The relationship between the maximum stress intensity factor and half-value breadth was expressed by the equation ω m α(K max /σ y ) 2 , where the value of α was 0.025. This is about one sixth of the value for ferritic steels, and the fact shows the severe work hardening occuring in the plastic zone in this manganese steel. (author)

  2. On the formation and nature of quasi-cleavage fracture surfaces in hydrogen embrittled steels

    Energy Technology Data Exchange (ETDEWEB)

    Martin, May L.; Fenske, Jamey A.; Liu, Grace S.; Sofronis, Petros [University of Illinois, Dept. of Materials Science and Engineering, 1304 W. Green St., Urbana, IL 61801 (United States); Robertson, Ian M., E-mail: ianr@illinois.edu [University of Illinois, Dept. of Materials Science and Engineering, 1304 W. Green St., Urbana, IL 61801 (United States)

    2011-02-15

    Quasi-cleavage, a common feature of hydrogen-induced fracture surfaces, is generally taken as being cleavage-like but not along a known cleavage plane. Despite the frequency with which this surface is observed, the relationship to the underlying microstructure remains unknown. Through a combination of topographical reconstruction of secondary electron microscope fractographs and a transmission electron microscopy study of the microstructure from site-specific locations, it will be shown that the features on quasi-cleavage surfaces are ridges that can be correlated with sub-surface intense and highly localized deformation bands. It will be demonstrated that the fracture surface arises from the growth and coalescence of voids that initiate at and extend along slip band intersections. This mechanism and process is fully consistent with hydrogen enhancing and localizing plastic processes.

  3. Influence of different surface treatments on the fracture toughness of a commercial ZTA dental ceramic

    Directory of Open Access Journals (Sweden)

    Flavio Teixeira da Silva

    2007-03-01

    Full Text Available The objective of this study was to investigate how mechanical surface treatments performed for removal of excess of molten glass, influence the fracture toughness of a dental zirconia toughened alumina (In-Ceram® Zirconia. Infiltrated ZTA disks were submitted to three different surface treatments (grinding, sandblasting and grinding + sandblasting + annealing. Fracture toughness was accessed through indentation strength test (IS. X ray diffraction was used to investigate the metastability of tetragonal zirconia particles under all treatments proposed. Kruskall-Wallis non-parametrical test and Weibull statistics were used to analyze the results. Grinding (group 1 introduced defects which decreased the fracture toughness and reliability, presenting the lowest K IC. On the other hand, grinding followed by sandblasting and annealing (group 3 presented the highest K IC. Sandblasting (group 2 presented the highest reliability but lower K IC compared to group 3.

  4. Fracture Failure Analysis of Fuel Pump Transmission Shaft of Dual-Fuel Engine

    Directory of Open Access Journals (Sweden)

    Chen Pei-hong

    2017-01-01

    Full Text Available NTS6ZLCz-129 dual-fuel turbocharged and intercooled engine durability test at 1000h, fuel pump shaft fractured. Fracture analysis, chemical analysis, microstructure examination and finite element stress analysis were carried out on the fractured shaft. The analysis result showed that the shaft fracture cause is forging fold. By improving the forging process, the forging fold was solved, and the durability test can be carried out smoothly.

  5. Analysis of energy flow during playground surface impacts.

    Science.gov (United States)

    Davidson, Peter L; Wilson, Suzanne J; Chalmers, David J; Wilson, Barry D; Eager, David; McIntosh, Andrew S

    2013-10-01

    The amount of energy dissipated away from or returned to a child falling onto a surface will influence fracture risk but is not considered in current standards for playground impact-attenuating surfaces. A two-mass rheological computer simulation was used to model energy flow within the wrist and surface during hand impact with playground surfaces, and the potential of this approach to provide insights into such impacts and predict injury risk examined. Acceleration data collected on-site from typical playground surfaces and previously obtained data from children performing an exercise involving freefalling with a fully extended arm provided input. The model identified differences in energy flow properties between playground surfaces and two potentially harmful surface characteristics: more energy was absorbed by (work done on) the wrist during both impact and rebound on rubber surfaces than on bark, and rubber surfaces started to rebound (return energy to the wrist) while the upper limb was still moving downward. Energy flow analysis thus provides information on playground surface characteristics and the impact process, and has the potential to identify fracture risks, inform the development of safer impact-attenuating surfaces, and contribute to development of new energy-based arm fracture injury criteria and tests for use in conjunction with current methods.

  6. An Improved Rate-Transient Analysis Model of Multi-Fractured Horizontal Wells with Non-Uniform Hydraulic Fracture Properties

    Directory of Open Access Journals (Sweden)

    Youwei He

    2018-02-01

    Full Text Available Although technical advances in hydraulically fracturing and drilling enable commercial production from tight reservoirs, oil/gas recovery remains at a low level. Due to the technical and economic limitations of well-testing operations in tight reservoirs, rate-transient analysis (RTA has become a more attractive option. However, current RTA models hardly consider the effect of the non-uniform production on rate decline behaviors. In fact, PLT results demonstrate that production profile is non-uniform. To fill this gap, this paper presents an improved RTA model of multi-fractured horizontal wells (MFHWs to investigate the effects of non-uniform properties of hydraulic fractures (production of fractures, fracture half-length, number of fractures, fracture conductivity, and vertical permeability on rate transient behaviors through the diagnostic type curves. Results indicate obvious differences on the rate decline curves among the type curves of uniform properties of fractures (UPF and non-uniform properties of fractures (NPF. The use of dimensionless production integral derivative curve magnifies the differences so that we can diagnose the phenomenon of non-uniform production. Therefore, it’s significant to incorporate the effects of NPF into the RDA models of MFHWs, and the model proposed in this paper enables us to better evaluate well performance based on long-term production data.

  7. X-ray fractographic study on fatigue fracture surface of structural steels

    International Nuclear Information System (INIS)

    Ogura, Keiji; Miyoshi, Yoshio; Kawaguchi, Masahiro; Kayama, Masahiro.

    1985-01-01

    An X-ray fractographic study was made on the fatigue fracture surface of the structural steels with various strength levels. An emphasis was put on examining the effect of strength level on the residual stress and half-value breadth on and under the fracture surface. It was found that the residual stress on the fracture surface was controlled by Ksub(max) in a low Ksub(max) or ΔK region (Region I), while it was controlled by ΔK rather than Ksub(max) in a high Ksub(max) or ΔK region (Region III). It was also found that another transitional region (Region II) was observed between these two regions in SNCM 815 steel. An explanation for all these behavior was discussed by a proposed model. The distribution of the residual stress and half-value breadth under the fracture surface was found to be usefull for estimating the value of Ksub(max), although the distribution itself was strongly influenced by strength level, particularly the work-softening behavior, of the materials. (author)

  8. Unified fluid flow model for pressure transient analysis in naturally fractured media

    International Nuclear Information System (INIS)

    Babak, Petro; Azaiez, Jalel

    2015-01-01

    Naturally fractured reservoirs present special challenges for flow modeling with regards to their internal geometrical structure. The shape and distribution of matrix porous blocks and the geometry of fractures play key roles in the formulation of transient interporosity flow models. Although these models have been formulated for several typical geometries of the fracture networks, they appeared to be very dissimilar for different shapes of matrix blocks, and their analysis presents many technical challenges. The aim of this paper is to derive and analyze a unified approach to transient interporosity flow models for slightly compressible fluids that can be used for any matrix geometry and fracture network. A unified fractional differential transient interporosity flow model is derived using asymptotic analysis for singularly perturbed problems with small parameters arising from the assumption of a much smaller permeability of the matrix blocks compared to that of the fractures. This methodology allowed us to unify existing transient interporosity flow models formulated for different shapes of matrix blocks including bounded matrix blocks, unbounded matrix cylinders with any orthogonal crossection, and matrix slabs. The model is formulated using a fractional order diffusion equation for fluid pressure that involves Caputo derivative of order 1/2 with respect to time. Analysis of the unified fractional derivative model revealed that the surface area-to-volume ratio is the key parameter in the description of the flow through naturally fractured media. Expressions of this parameter are presented for matrix blocks of the same geometrical shape as well as combinations of different shapes with constant and random sizes. Numerical comparisons between the predictions of the unified model and those obtained from existing transient interporosity ones for matrix blocks in the form of slabs, spheres and cylinders are presented for linear, radial and spherical flow types for

  9. Influence of Structural Features and Fracture Processes on Surface Roughness: A Case Study from the Krosno Sandstones of the Górka–Mucharz Quarry (Little Beskids, Southern Poland

    Directory of Open Access Journals (Sweden)

    Pieczara Łukasz

    2015-09-01

    Full Text Available The paper presents the results of analysis of surface roughness parameters in the Krosno Sandstones of Mucharz, southern Poland. It was aimed at determining whether these parameters are influenced by structural features (mainly the laminar distribution of mineral components and directional distribution of non-isometric grains and fracture processes. The tests applied in the analysis enabled us to determine and describe the primary statistical parameters used in the quantitative description of surface roughness, as well as specify the usefulness of contact profilometry as a method of visualizing spatial differentiation of fracture processes in rocks. These aims were achieved by selecting a model material (Krosno Sandstones from the Górka-Mucharz Quarry and an appropriate research methodology. The schedule of laboratory analyses included: identification analyses connected with non-destructive ultrasonic tests, aimed at the preliminary determination of rock anisotropy, strength point load tests (cleaved surfaces were obtained due to destruction of rock samples, microscopic analysis (observation of thin sections in order to determine the mechanism of inducing fracture processes and a test method of measuring surface roughness (two- and three-dimensional diagrams, topographic and contour maps, and statistical parameters of surface roughness. The highest values of roughness indicators were achieved for surfaces formed under the influence of intragranular fracture processes (cracks propagating directly through grains. This is related to the structural features of the Krosno Sandstones (distribution of lamination and bedding.

  10. Fracture resistance of dental nickel–titanium rotary instruments with novel surface treatment: Thin film metallic glass coating

    Directory of Open Access Journals (Sweden)

    Chih-Wen Chi

    2017-05-01

    Conclusion: The novel surface treatment of Ti-Zr-B thin film metallic glass on dental NiTi rotary files can effectively improve the fatigue fracture resistance by offering a smooth coated surface with amorphous microstructure.

  11. NASGRO(registered trademark): Fracture Mechanics and Fatigue Crack Growth Analysis Software

    Science.gov (United States)

    Forman, Royce; Shivakumar, V.; Mettu, Sambi; Beek, Joachim; Williams, Leonard; Yeh, Feng; McClung, Craig; Cardinal, Joe

    2004-01-01

    This viewgraph presentation describes NASGRO, which is a fracture mechanics and fatigue crack growth analysis software package that is used to reduce risk of fracture in Space Shuttles. The contents include: 1) Consequences of Fracture; 2) NASA Fracture Control Requirements; 3) NASGRO Reduces Risk; 4) NASGRO Use Inside NASA; 5) NASGRO Components: Crack Growth Module; 6) NASGRO Components:Material Property Module; 7) Typical NASGRO analysis: Crack growth or component life calculation; and 8) NASGRO Sample Application: Orbiter feedline flowliner crack analysis.

  12. Fracture Surface Morphology Under Ductile Tearing of Metal Plates

    DEFF Research Database (Denmark)

    Kacar, Muhammet F.; Tekoglu, Cihan; Nielsen, Kim Lau

    2017-01-01

    The present work takes as offset the hypothesis that microstructural parameters, related to particle size and distribution, govern the transition between crack surface morphologies observed in experiments. The key question is; why does tearing of a given metal plate leave a specific morphology...

  13. Fracture Analysis of the FAA/NASA Wide Stiffened Panels

    Science.gov (United States)

    Seshadri, B. R.; Newman, J. C., Jr.; Dawicke, D. S.; Young, R. D.

    1999-01-01

    This paper presents the fracture analyses conducted on the FAA/NASA stiffened and unstiffened panels using the STAGS (STructural Analysis of General Shells) code with the critical crack-tip-opening angle (CTOA) fracture criterion. The STAGS code with the "plane-strain" core option was used in all analyses. Previous analyses of wide, flat panels have shown that the high-constraint conditions around a crack front, like plane strain, has to be modeled in order for the critical CTOA fracture criterion to predict wide panel failures from small laboratory tests. In the present study, the critical CTOA value was determined from a wide (unstiffened) panel with anti-buckling guides. The plane-strain core size was estimated from previous fracture analyses and was equal to about the sheet thickness. Rivet flexibility and stiffener failure was based on methods and criteria, like that currently used in industry. STAGS and the CTOA criterion were used to predict load-against-crack extension for the wide panels with a single crack and multiple-site damage cracking at many adjacent rivet holes. Analyses were able to predict stable crack growth and residual strength within a few percent (5%) of stiffened panel tests results but over predicted the buckling failure load on an unstiffened panel with a single crack by 10%.

  14. X-ray fractography of fatigue fracture surface under mode I and mode III loading

    International Nuclear Information System (INIS)

    Akiniwa, Yoshiaki; Tanaka, Keisuke; Tsumura, Tsuyoshi

    2001-01-01

    The propagation behavior of a circumferential fatigue crack in cylindrical bars of a carbon steel (JIS SGV410) and a stainless steel (JIS SUS316NG) was investigated under cyclic axial and torsional loadings. The J-integral range was used as a fracture mechanics parameter. When compared at the same J-integral range, the crack propagation rate under mode III was smaller than that under mode I. Parallel markings perpendicular to the crack propagation direction were observed on the fatigue fracture surface obtained under mode III loading. The residual stresses in the radial direction, σ r , and in the tangential direction, σ θ , were measured for both mode I and mode III fatigue fracture surfaces. For mode I fracture surface, σ r was tension, and was almost constant irrespective of the applied J-integral range. σ θ was close to zero for both materials. On the other hand, for mode III, σ r and σ θ were compression. For SUS316NG steel, the compressive stress of σ θ increased with the J-integral range. For SGV410 steel, the change of σ θ with the J-integral range was small. The breadth of diffraction profiles increased with J-integral range for both mode I and III. The breadth was found to be a good parameter to evaluate the applied J-integral range. (author)

  15. Fracture Surface Morphology and Impact Strength of Cellulose/PLA Composites.

    Science.gov (United States)

    Gao, Honghong; Qiang, Tao

    2017-06-07

    Polylactide (PLA)-based composite materials reinforced with ball-milled celluloses were manufactured by extrusion blending followed by injection molding. Their surface morphology from impact fracture were imaged with scanning electron microscopy (SEM) and investigated by calculating their fractal dimensions. Then, linear regression was used to explore the relationship between fractal dimension and impact strength of the resultant cellulose/PLA composite materials. The results show that filling the ball-milled celluloses into PLA can improve the impact toughness of PLA by a minimum of 38%. It was demonstrated that the fracture pattern of the cellulose/PLA composite materials is different from that of pristine PLA. For the resultant composite materials, the fractal dimension of the impact fractured surfaces increased with increasing filling content and decreasing particle size of the ball-milled cellulose particles. There were highly positive correlations between fractal dimension of the fractured surfaces and impact strength of the cellulose/PLA composites. However, the linearity between fractal dimension and impact strength were different for the different methods, due to their different R-squared values. The approach presented in this work will help to understand the structure-property relationships of composite materials from a new perspective.

  16. Tidal Disruption of Phobos as the Cause of Surface Fractures

    Science.gov (United States)

    Hurford, T. A.; Asphaug, E.; Spitale, J. N.; Hemingway, D.; Rhoden, A. R.; Henning, W. G.; Bills, B. G.; Kattenhorn, S. A.; Walker, M.

    2016-01-01

    Phobos, the innermost satellite of Mars, displays an extensive system of grooves that are mostly symmetric about its sub-Mars point. Phobos is steadily spiraling inward due to the tides it raises on Mars lagging behind Phobos' orbital position and will suffer tidal disruption before colliding with Mars in a few tens of millions of years. We calculate the surface stress field of the deorbiting satellite and show that the first signs of tidal disruption are already present on its surface. Most of Phobos' prominent grooves have an excellent correlation with computed stress orientations. The model requires a weak interior that has very low rigidity on the tidal evolution time scale, overlain by an approximately 10-100 m exterior shell that has elastic properties similar to lunar regolith as described by Horvath et al. (1980).

  17. Thermal image analysis of plastic deformation and fracture behavior by a thermo-video measurement system

    International Nuclear Information System (INIS)

    Ohbuchi, Yoshifumi; Sakamoto, Hidetoshi; Nagatomo, Nobuaki

    2016-01-01

    The visualization of the plastic region and the measurement of its size are necessary and indispensable to evaluate the deformation and fracture behavior of a material. In order to evaluate the plastic deformation and fracture behavior in a structural member with some flaws, the authors paid attention to the surface temperature which is generated by plastic strain energy. The visualization of the plastic deformation was developed by analyzing the relationship between the extension of the plastic deformation range and the surface temperature distribution, which was obtained by an infrared thermo-video system. Furthermore, FEM elasto-plastic analysis was carried out with the experiment, and the effectiveness of this non-contact measurement system of the plastic deformation and fracture process by a thermography system was discussed. The evaluation method using an infrared imaging device proposed in this research has a feature which does not exist in the current evaluation method, i.e. the heat distribution on the surface of the material has been measured widely by noncontact at 2D at high speed. The new measuring technique proposed here can measure the macroscopic plastic deformation distribution on the material surface widely and precisely as a 2D image, and at high speed, by calculation from the heat generation and the heat propagation distribution. (paper)

  18. Numerical Fracture Analysis of Cryogenically Treated Alloy Steel Weldments

    International Nuclear Information System (INIS)

    Rasool Mohideen, S; Thamizhmanii, S; Muhammed Abdul Fatah, M.M; Saidin, W. Najmuddin W.

    2016-01-01

    Cryogenic treatment is being used commercially in the industries in the last two decades for improving the life of many engineering component such as bearings and cutting tools. Though their influence in improving the wear resistance of tool materials is well established, the effect of treatment on weldments is not much investigated. In the present work, a two dimensional finite element analysis was carried out on the compact tension specimen model for simulating the treatment process and to study the fracture behaviour. The weldments were modelled by thermo- mechanical coupled field analysis for simulating he temperature distribution in the model during weld pool cooling and introducing thermal stresses due to uneven contraction and cooling. The model was subjected to cryogenic treatment by adopting radiation effect. The fracture analysis was carried out using Rice's J- Integral approach. The analysis produced a similar outcome of experimental results i.e. Increase in the fracture toughness of the specimen after cryogenic treatment in the heat affected zone of weldment. (paper)

  19. Monitoring Induced Fractures with Electrical Measurements using Depth to Surface Resistivity: A Field Case Study

    Science.gov (United States)

    Wilt, M.; Nieuwenhuis, G.; Sun, S.; MacLennan, K.

    2016-12-01

    Electrical methods offer an attractive option to map induced fractures because the recovered anomaly is related to the electrical conductivity of the injected fluid in the open (propped) section of the fracture operation. This is complementary to existing micro-seismic technology, which maps the mechanical effects of the fracturing. In this paper we describe a 2014 field case where a combination of a borehole casing electrode and a surface receiver array was used to monitor hydrofracture fracture creation and growth in an unconventional oil field project. The fracture treatment well was 1 km long and drilled to a depth of 2.2 km. Twelve fracture events were induced in 30 m intervals (stages) in the 1 km well. Within each stage 5 events (clusters) were initiated at 30 m intervals. Several of the fracture stages used a high salinity brine, instead of fresh water, to enhance the electrical signal. The electrical experiment deployed a downhole source in a well parallel to the treatment well and 100 m away. The source consisted of an electrode attached to a wireline cable into which a 0.25 Hz square wave was injected. A 60-station electrical field receiver array was placed above the fracture and extending for several km. Receivers were oriented to measure electrical field parallel with the presumed fracture direction and those perpendicular to it. Active source electrical data were collected continuously during 7 frac stages, 3 of which used brine as the frac fluid over a period of several days. Although the site was quite noisy and the electrical anomaly small we managed to extract a clear frac anomaly using field separation, extensive signal averaging and background noise rejection techniques. Preliminary 3D modeling, where we account for current distribution of the casing electrode and explicitly model multiple thin conductive sheets to represent fracture stages, produces a model consistent with the field measurements and also highlights the sensitivity of the

  20. Surface Reconstruction from Parallel Curves with Application to Parietal Bone Fracture Reconstruction.

    Directory of Open Access Journals (Sweden)

    Abdul Majeed

    Full Text Available Maxillofacial trauma are common, secondary to road traffic accident, sports injury, falls and require sophisticated radiological imaging to precisely diagnose. A direct surgical reconstruction is complex and require clinical expertise. Bio-modelling helps in reconstructing surface model from 2D contours. In this manuscript we have constructed the 3D surface using 2D Computerized Tomography (CT scan contours. The fracture part of the cranial vault are reconstructed using GC1 rational cubic Ball curve with three free parameters, later the 2D contours are flipped into 3D with equidistant z component. The constructed surface is represented by contours blending interpolant. At the end of this manuscript a case report of parietal bone fracture is also illustrated by employing this method with a Graphical User Interface (GUI illustration.

  1. Analysis of Fractured Teeth Utilizing Digital Microscopy: A Pilot Study

    Science.gov (United States)

    2016-06-01

    pathology (8). Artifacts such as beam hardening, streaking and cupping may limit the clinician’s ability to detect fractures (9). Metallic structures...visualization of a pathologic condition in the area of diagnostic interest (9). There have been multiple studies published which measure the size of...Heimel P, Metscher B. Volume analysis of heat-induced cracks in human molars: A preliminary study. J Forensic Dent Sci 2014;6:139-44. 13. Hunter J

  2. Applications of Automation Methods for Nonlinear Fracture Test Analysis

    Science.gov (United States)

    Allen, Phillip A.; Wells, Douglas N.

    2013-01-01

    Using automated and standardized computer tools to calculate the pertinent test result values has several advantages such as: 1. allowing high-fidelity solutions to complex nonlinear phenomena that would be impractical to express in written equation form, 2. eliminating errors associated with the interpretation and programing of analysis procedures from the text of test standards, 3. lessening the need for expertise in the areas of solid mechanics, fracture mechanics, numerical methods, and/or finite element modeling, to achieve sound results, 4. and providing one computer tool and/or one set of solutions for all users for a more "standardized" answer. In summary, this approach allows a non-expert with rudimentary training to get the best practical solution based on the latest understanding with minimum difficulty.Other existing ASTM standards that cover complicated phenomena use standard computer programs: 1. ASTM C1340/C1340M-10- Standard Practice for Estimation of Heat Gain or Loss Through Ceilings Under Attics Containing Radiant Barriers by Use of a Computer Program 2. ASTM F 2815 - Standard Practice for Chemical Permeation through Protective Clothing Materials: Testing Data Analysis by Use of a Computer Program 3. ASTM E2807 - Standard Specification for 3D Imaging Data Exchange, Version 1.0 The verification, validation, and round-robin processes required of a computer tool closely parallel the methods that are used to ensure the solution validity for equations included in test standard. The use of automated analysis tools allows the creation and practical implementation of advanced fracture mechanics test standards that capture the physics of a nonlinear fracture mechanics problem without adding undue burden or expense to the user. The presented approach forms a bridge between the equation-based fracture testing standards of today and the next generation of standards solving complex problems through analysis automation.

  3. Fracture Analysis of Functionally Graded Materials

    International Nuclear Information System (INIS)

    Zhang, Ch.; Gao, X. W.; Sladek, J.; Sladek, V.

    2010-01-01

    This paper reports our recent research works on crack analysis in continuously non-homogeneous and linear elastic functionally graded materials. A meshless boundary element method is developed for this purpose. Numerical examples are presented and discussed to demonstrate the efficiency and the accuracy of the present numerical method, and to show the effects of the material gradation on the crack-opening-displacements and the stress intensity factors.

  4. Titanium and steel fracture fixation plates with different surface topographies: Influence on infection rate in a rabbit fracture model.

    Science.gov (United States)

    Metsemakers, W J; Schmid, Tanja; Zeiter, Stephan; Ernst, Manuela; Keller, Iris; Cosmelli, Nicolo; Arens, Daniel; Moriarty, T Fintan; Richards, R Geoff

    2016-03-01

    Implant-related infection is a challenging complication in musculoskeletal trauma surgery. In the present study, we examined the role of implant material and surface topography as influencing factors on the development of infection in an experimental model of plating osteosynthesis in the rabbit. The implants included in this experimental study were composed of: standard Electropolished Stainless Steel (EPSS), standard titanium (Ti-S), roughened stainless steel (RSS) and surface polished titanium (Ti-P). Construct stability and load-to-failure of Ti-P implants was compared to that of Ti-S implants in a rabbit cadaveric model. In an in vivo study, a rabbit humeral fracture model was used. Each rabbit received one of three Staphylococcus aureus inocula, aimed at determining the infection rate at a low, medium and high dose of bacteria. Outcome measures were quantification of bacteria on the implant and in the surrounding tissues, and determination of the infectious dose 50 (ID50). No significant differences were observed between Ti-S and Ti-P regarding stiffness or failure load in the cadaver study. Of the 72 rabbits eventually included in the in vivo study, 50 developed an infection. The ID50 was found to be: EPSS 3.89×10(3) colony forming units (CFU); RSS 8.23×10(3) CFU; Ti-S 5.66×10(3) CFU; Ti-P 3.41×10(3) CFU. Significantly lower bacterial counts were found on the Ti-S implants samples compared with RSS implants (ptitanium and steel implants with conventional or modified topographies. Ti-P implants, which have previously been shown in preclinical studies to reduce complications associated with tissue adherence, do not affect infection rate in this preclinical fracture model. Therefore, Ti-P implants are not expected to affect the infection rate, or influence implant stability in the clinical situation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Surface analysis the principal techniques

    CERN Document Server

    Vickerman, John C

    2009-01-01

    This completely updated and revised second edition of Surface Analysis: The Principal Techniques, deals with the characterisation and understanding of the outer layers of substrates, how they react, look and function which are all of interest to surface scientists. Within this comprehensive text, experts in each analysis area introduce the theory and practice of the principal techniques that have shown themselves to be effective in both basic research and in applied surface analysis. Examples of analysis are provided to facilitate the understanding of this topic and to show readers how they c

  6. The relationship of seismic velocity structure and surface fracture characteristics of basalt outcrops to rippability estimates

    International Nuclear Information System (INIS)

    Kay, S.E.; Dougherty, M.E.; Pelton, J.R.

    1994-01-01

    Seismic velocity has been shown in previous engineering studies to be related to the fracture characteristics and rippability of rock outcrops. However, common methods of measuring seismic velocity in outcrops do not take into account the many possible travel paths for wave propagation and the fact that velocity zones may exist within an outcrop. Presented here are the results of using raytracing inversion of first-arrival travel-time data to map P-velocity structure in basalt outcrops, and also the investigation of the relationship of the mapped velocities to observed surface fractures and hand-sample P-velocities. It is shown that basalt outcrops commonly consist of an irregular near-surface low-velocity zone underlain by higher velocity material; that velocity gradients can exist in outcrops; that hand-sample velocity measurements are typically higher than outcrop-scale measurements; and that the characteristics of surface fractures are empirically related to near-surface P-velocity. All of these findings are relevant to the estimated rippability of rock in geotechnical engineering. The data for this study are derived from eleven sites on basalt outcrops of the Troodos Ophiolite in Cyprus. The basalt types include pillow basalts, massive flows, and a pillow breccia. A commonly available raytracing inversion program (RAYINVR) was used to produce a velocity profile of each outcrop. Different velocity zones were detailed by inverting observed travel times to produce a model of outcrop velocity structure which produces rippability profiles for each outcrop. 16 refs., 9 figs

  7. Evaluation of viscoplastic fracture criteria and analysis methods

    International Nuclear Information System (INIS)

    Bass, B.R.; Pugh, C.E.; Keeney-Walker, J.; Dexter, R.J.; O'Donoghue, P.E.; Schwartz, C.W.

    1988-01-01

    The role of nonlinear rate-dependent effects in the interpretation of crack run-arrest events in ductile materials is being investigated by the Heavy-Section Steel Technology (HSST) program through development and applications of viscoplastic-dynamic finite element analysis techniques. This paper describes a portion of these studies wherein various viscoplastic constitutive models and several proposed nonlinear fracture criteria are being installed in general purpose (ADINA) and special purpose (VISCRK) finite element computer programs. The formulations of the Bodner-Partom, the Perzyna, and the Robinson constitutive models installed in the HSST computer programs are summarized. This is followed by a description of three integral functions that are candidate fracture parameters. The capabilities of these nonlinear techniques re compared and evaluated through applications to one of the HSST wide-plate crack-arrest tests. Results are presented from benchmark viscoplastic-dynamic wide-plate analyses performed using the ADINA and VISCRK computer programs. Finally, plans are summarized for additional computational and experimental studies to assess the utility of viscoplastic analysis techniques in constructing a transferable inelastic fracture mechanics model for ductile steels. (author)

  8. Probabilistic finite elements for fatigue and fracture analysis

    Science.gov (United States)

    Belytschko, Ted; Liu, Wing Kam

    1993-04-01

    An overview of the probabilistic finite element method (PFEM) developed by the authors and their colleagues in recent years is presented. The primary focus is placed on the development of PFEM for both structural mechanics problems and fracture mechanics problems. The perturbation techniques are used as major tools for the analytical derivation. The following topics are covered: (1) representation and discretization of random fields; (2) development of PFEM for the general linear transient problem and nonlinear elasticity using Hu-Washizu variational principle; (3) computational aspects; (4) discussions of the application of PFEM to the reliability analysis of both brittle fracture and fatigue; and (5) a stochastic computational tool based on stochastic boundary element (SBEM). Results are obtained for the reliability index and corresponding probability of failure for: (1) fatigue crack growth; (2) defect geometry; (3) fatigue parameters; and (4) applied loads. These results show that initial defect is a critical parameter.

  9. Fracture analysis for engineering geological utilization

    Energy Technology Data Exchange (ETDEWEB)

    Choi, H I; Choi, P Y; Hong, S H; Chi, K H; Kim, J Y; Lee, S R; Lee, S G; Park, D W; Han, J G [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)

    1997-12-01

    The problem of geological hazards (earthquakes) and water or thermal resources urges us to understand the regional tectonic setting or recent tectonics. The Uisong Subbasin is located in one of the seismicity zones in Korea. Because the reactivity of the Gaeum Fault System is an important problem focussing on these faults, we studied their whole extension and timing of faulting in terms of tectonics. Fault tectonic analysis is so effective as to easily reconstruct the tectonic sequence and each stress state at each site, eventually in a region. One can get insights for faulting timing in terms of the restored tectonic sequence, and discriminating the active faults or the faults active in the last (present) tectonics. Examining the filling materials in tension gashes, one can get raw knowledge regarding the thermal states at each site. For this study, we first analyzed the topographic textures (lineament, drainage and circular structures) on the relief map produced based on the topographic maps of 1:100,000 scale. Through investigations of susceptible area along the faults, their existence and movement modes were studied, and we can get information about movement history and whole extension of the faults belonging to the WNW-ESE trending Gaeum Fault System. In order to reconstruct the tectonic sequence, we measured fault slip data, tension gashes and dikes, from which fault populations were classified and stress (and thermal) states were determined. Seven compressional tectonic events and six extensional events were reconstructed. Because coaxial events partially coexisted, we bundled these events in one, finally we get seven tectonic events. Determining the types of minerals filling the tension gashes, we suggested the possibility of investigation of geothermal resources with less efforts. (author). 162 refs., 14 tabs., 51 figs.

  10. Three-Dimensional Geostatistical Analysis of Rock Fracture Roughness and Its Degradation with Shearing

    Directory of Open Access Journals (Sweden)

    Nima Babanouri

    2013-12-01

    Full Text Available Three-dimensional surface geometry of rock discontinuities and its evolution with shearing are of great importance in understanding the deformability and hydro-mechanical behavior of rock masses. In the present research, surfaces of three natural rock fractures were digitized and studied before and after the direct shear test. The variography analysis of the surfaces indicated a strong non-linear trend in the data. Therefore, the spatial variability of rock fracture surfaces was decomposed to one deterministic component characterized by a base polynomial function, and one stochastic component described by the variogram of residuals. By using an image-processing technique, 343 damaged zones with different sizes, shapes, initial roughness characteristics, local stress fields, and asperity strength values were spatially located and clustered. In order to characterize the overall spatial structure of the degraded zones, the concept of ‘pseudo-zonal variogram’ was introduced. The results showed that the spatial continuity at the damage locations increased due to asperity degradation. The increase in the variogram range was anisotropic and tended to be higher in the shear direction; thus, the direction of maximum continuity rotated towards the shear direction. Finally, the regression-kriging method was used to reconstruct the morphology of the intact surfaces and degraded areas. The cross-validation error of interpolation for the damaged zones was found smaller than that obtained for the intact surface.

  11. Numerical analysis of standard and modified osteosynthesis in long bone fractures treatment.

    Science.gov (United States)

    Sisljagić, Vladimir; Jovanović, Savo; Mrcela, Tomislav; Radić, Radivoje; Selthofer, Robert; Mrcela, Milanka

    2010-03-01

    The fundamental problem in osteoporotic fracture treatment is significant decrease in bone mass and bone tissue density resulting in decreased firmness and elasticity of osteoporotic bone. Application of standard implants and standard surgical techniques in osteoporotic bone fracture treatment makes it almost impossible to achieve stable osteosynthesis sufficient for early mobility, verticalization and load. Taking into account the form and the size of the contact surface as well as distribution of forces between the osteosynthetic materials and the bone tissue numerical analysis showed advantages of modified osteosynthesis with bone cement filling in the screw bed. The applied numerical model consisted of three sub-models: 3D model from solid elements, 3D cross section of the contact between the plate and the bone and the part of 3D cross section of the screw head and body. We have reached the conclusion that modified osteosynthesis with bone cement resulted in weaker strain in the part of the plate above the fracture fissure, more even strain on the screws, plate and bone, more even strain distribution along all the screws' bodies, significantly greater strain in the part of the screw head opposite to the fracture fissure, firm connection of the screw head and neck and the plate hole with the whole plate and more even bone strain around the screw.

  12. Analysis of the applicability of fracture mechanics on the basis of large scale specimen testing

    International Nuclear Information System (INIS)

    Brumovsky, M.; Polachova, H.; Sulc, J.; Anikovskij, V.; Dragunov, Y.; Rivkin, E.; Filatov, V.

    1988-01-01

    The verification is dealt with of fracture mechanics calculations for WWER reactor pressure vessels by large scale model testing performed on the large testing machine ZZ 8000 (maximum load of 80 MN) in the Skoda Concern. The results of testing a large set of large scale test specimens with surface crack-type defects are presented. The nominal thickness of the specimens was 150 mm with defect depths between 15 and 100 mm, the testing temperature varying between -30 and +80 degC (i.e., in the temperature interval of T ko ±50 degC). Specimens with a scale of 1:8 and 1:12 were also tested, as well as standard (CT and TPB) specimens. Comparisons of results of testing and calculations suggest some conservatism of calculations (especially for small defects) based on Linear Elastic Fracture Mechanics, according to the Nuclear Reactor Pressure Vessel Codes which use the fracture mechanics values from J IC testing. On the basis of large scale tests the ''Defect Analysis Diagram'' was constructed and recommended for brittle fracture assessment of reactor pressure vessels. (author). 7 figs., 2 tabs., 3 refs

  13. Plastic fracture mechanics prediction of fracture instability in a circumferentially cracked pipe in bending - 1. J-integral analysis

    Energy Technology Data Exchange (ETDEWEB)

    Zahoor, A.; Kanninen, M.F.

    1981-11-01

    A method of evaluating the J-integral for a circumferentially cracked pipe in bending is proposed. The method allows a J-resistance curve to be evaluated directly from the load-displacement record obtained in a pipe fracture experiment. It permits an analysis for fracture instability in a circumferential crack growth using a J-resistance curve and the tearing modulus parameter. The influence of the system compliance on fracture instability is discussed in conjunction with the latter application. The importance of using a J-resistance curve that is consistent with the type of constraint for a given application is emphasized. The possibility of a pipe fracture emanating from a stress corrosion crack in the heat-affected zones of girth-welds in Type 304 stainless steel pipes was investigated. The J-resistance curve was employed. A pipe fracture experiment was performed using a spring-loaded four-point bending system that simulated an 8.8-m long section of unsupported 102-mm-dia pipe. An initial through-wall crack of length equal to 104 mm was used. Fracture instability was predicted to occur between 15.2 and 22.1 mm of stable crack growth at each tip. In the actual experiment, the onset of fracture instability occurred beyond maximum load at an average stable crack growth of 11.7 to 19 mm at each tip. 24 refs.

  14. Plastic fracture mechanics prediction of fracture instability in a circumferentially cracked pipe in bending - 1. J-integral analysis

    International Nuclear Information System (INIS)

    Zahoor, A.; Kanninen, M.F.

    1981-01-01

    A method of evaluating the J-integral for a circumferentially cracked pipe in bending is proposed. The method allows a J-resistance curve to be evaluated directly from the load-displacement record obtained in a pipe fracture experiment. It permits an analysis for fracture instability in a circumferential crack growth using a J-resistance curve and the tearing modulus parameter. The influence of the system compliance on fracture instability is discussed in conjunction with the latter application. The importance of using a J-resistance curve that is consistent with the type of constraint for a given application is emphasized. The possibility of a pipe fracture emanating from a stress corrosion crack in the heat-affected zones of girth-welds in Type 304 stainless steel pipes was investigated. The J-resistance curve was employed. A pipe fracture experiment was performed using a spring-loaded four-point bending system that simulated an 8.8-m long section of unsupported 102-mm-dia pipe. An initial through-wall crack of length equal to 104 mm was used. Fracture instability was predicted to occur between 15.2 and 22.1 mm of stable crack growth at each tip. In the actual experiment, the onset of fracture instability occurred beyond maximum load at an average stable crack growth of 11.7 to 19 mm at each tip. 24 refs

  15. The effect of crack propagation mechanism on the fractal dimension of fracture surfaces in steels

    Czech Academy of Sciences Publication Activity Database

    Dlouhý, Ivo; Strnadel, B.

    2008-01-01

    Roč. 75, č. 3-4 (2008), s. 726-738 ISSN 0013-7944 R&D Projects: GA ČR(CZ) GA106/06/0646; GA AV ČR IAA200410502 Institutional research plan: CEZ:AV0Z20410507 Keywords : low-alloyed steel * fracture surface * fractography Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.713, year: 2008

  16. Hybrid external fixation in the treatment of tibial pilon fractures: A retrospective analysis of 162 fractures.

    Science.gov (United States)

    Galante, Vito N; Vicenti, Giovanni; Corina, Gianfranco; Mori, Claudio; Abate, Antonella; Picca, Girolamo; Conserva, Vito; Speciale, Domenico; Scialpi, Lorenzo; Tartaglia, Nicola; Caiaffa, Vincenzo; Moretti, Biagio

    2016-10-01

    To determine the efficacy of hybrid external fixation in the treatment of tibial pilon fractures. Retrospective, multicentre study. Adult patients with tibial pilon fractures treated with hybrid external fixation. Fracture reduction with ligamentotaxis and fixation with XCaliber hybrid external fixator. Fracture union, complications, functional outcome (Mazur Ankle Score). Union was obtained in 159 fractures at an average of 125days; there were three delayed unions and three non-unions. The most frequent complication was superficial pin-track infections (48), all of which responded to local wound care and antibiotics. There were no deep infections and no DVT. Only one fracture had loss of reduction that required frame revision. The overall functional scores were 91 (excellent) for AO/OTA type A fractures, 89 (good) for type B fractures, and 75 (satisfactory) for type C fractures. Hybrid external fixation is an effective method of stabilising tibial pilon fractures, particularly those with marked comminution. The minimally-invasive technique and stable fixation enable early mobilisation, with good functional results and minimal complications. Level IV Case series. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Dispersion analysis for waves propagated in fractured media

    Energy Technology Data Exchange (ETDEWEB)

    Lesniak, A; Niitsuma, H [Tohoku University, Sendai (Japan). Faculty of Engineering

    1996-05-01

    Dispersion of velocity is defined as a variation of the phase velocity with frequency. This paper describes the dispersion analysis of compressional body waves propagated in the heterogeneous fractured media. The new method proposed and discussed here permitted the evaluation of the variation in P wave arrival with frequency. For this processing method, any information about the attenuation of the medium are not required, and only an assumption of weak heterogeneity is important. It was shown that different mechanisms of dispersion can be distinguished and its value can be quantitatively estimated. Although the frequency used in this study was lower than those in most previous experiments reported in literature, the evaluated dispersion was large. It was suggested that such a large dispersion may be caused by the velocity structure of the media studied and by frequency dependent processes in a highly fractured zone. It was demonstrated that the present method can be used in the evaluation of subsurface fracture systems or characterization of any kind of heterogeneities. 10 refs., 6 figs.

  18. Surface Temperature Data Analysis

    Science.gov (United States)

    Hansen, James; Ruedy, Reto

    2012-01-01

    Small global mean temperature changes may have significant to disastrous consequences for the Earth's climate if they persist for an extended period. Obtaining global means from local weather reports is hampered by the uneven spatial distribution of the reliably reporting weather stations. Methods had to be developed that minimize as far as possible the impact of that situation. This software is a method of combining temperature data of individual stations to obtain a global mean trend, overcoming/estimating the uncertainty introduced by the spatial and temporal gaps in the available data. Useful estimates were obtained by the introduction of a special grid, subdividing the Earth's surface into 8,000 equal-area boxes, using the existing data to create virtual stations at the center of each of these boxes, and combining temperature anomalies (after assessing the radius of high correlation) rather than temperatures.

  19. Fundamentals of Reservoir Surface Energy as Related to Surface Properties, Wettability, Capillary Action, and Oil Recovery from Fractured Reservoirs by Spontaneous Imbibition

    Energy Technology Data Exchange (ETDEWEB)

    Norman Morrow; Herbert Fischer; Yu Li; Geoffrey Mason; Douglas Ruth; Siddhartha Seth; Zhengxin Tong; Evren Unsal; Siluni Wickramathilaka; Shaochang Wo; Peigui Yin

    2008-06-30

    The objective of this project is to increase oil recovery from fractured reservoirs through improved fundamental understanding of the process of spontaneous imbibition by which oil is displaced from the rock matrix into the fractures. Spontaneous imbibition is fundamentally dependent on the reservoir surface free energy but this has never been investigated for rocks. In this project, the surface free energy of rocks will be determined by using liquids that can be solidified within the rock pore space at selected saturations. Thin sections of the rock then provide a two-dimensional view of the rock minerals and the occupant phases. Saturations and oil/rock, water/rock, and oil/water surface areas will be determined by advanced petrographic analysis and the surface free energy which drives spontaneous imbibition will be determined as a function of increase in wetting phase saturation. The inherent loss in surface free energy resulting from capillary instabilities at the microscopic (pore level) scale will be distinguished from the decrease in surface free energy that drives spontaneous imbibition. A mathematical network/numerical model will be developed and tested against experimental results of recovery versus time over broad variation of key factors such as rock properties, fluid phase viscosities, sample size, shape and boundary conditions. Two fundamentally important, but not previously considered, parameters of spontaneous imbibition, the capillary pressure acting to oppose production of oil at the outflow face and the pressure in the non-wetting phase at the no-flow boundary versus time, will also be measured and modeled. Simulation and network models will also be tested against special case solutions provided by analytic models. In the second stage of the project, application of the fundamental concepts developed in the first stage of the project will be demonstrated. The fundamental ideas, measurements, and analytic/numerical modeling will be applied to mixed

  20. FUNDAMENTALS OF RESERVOIR SURFACE ENERGY AS RELATED TO SURFACE PROPERTIES, WETTABILITY, CAPILLARY ACTION, AND OIL RECOVERY FROM FRACTURED RESERVOIRS BY SPONTANEOUS IMBIBITION

    Energy Technology Data Exchange (ETDEWEB)

    Norman R. Morrow

    2004-05-01

    The objective of this project is to increase oil recovery from fractured reservoirs through improved fundamental understanding of the process of spontaneous imbibition by which oil is displaced from the rock matrix into the fractures. Spontaneous imbibition is fundamentally dependent on the reservoir surface free energy but this has never been investigated for rocks. In this project, the surface free energy of rocks will be determined by using liquids that can be solidified within the rock pore space at selected saturations. Thin sections of the rock then provide a two-dimensional view of the rock minerals and the occupant phases. Saturations and oil/rock, water/rock, and oil/water surface areas will be determined by advanced petrographic analysis and the surface free energy which drives spontaneous imbibition will be determined as a function of increase in wetting phase saturation. The inherent loss in surface free energy resulting from capillary instabilities at the microscopic (pore level) scale will be distinguished from the decrease in surface free energy that drives spontaneous imbibition. A mathematical network/numerical model will be developed and tested against experimental results of recovery versus time over broad variation of key factors such as rock properties, fluid phase viscosities, sample size, shape and boundary conditions. Two fundamentally important, but not previously considered, parameters of spontaneous imbibition, the capillary pressure acting to oppose production of oil at the outflow face and the pressure in the nonwetting phase at the no-flow boundary versus time, will also be measured and modeled. Simulation and network models will also be tested against special case solutions provided by analytic models. In the second stage of the project, application of the fundamental concepts developed in the first stage of the project will be demonstrated. The fundamental ideas, measurements, and analytic/numerical modeling will be applied to mixed

  1. FUNDAMENTALS OF RESERVOIR SURFACE ENERGY AS RELATED TO SURFACE PROPERTIES, WETTABILITY, CAPILLARY ACTION, AND OIL RECOVERY FROM FRACTURED RESERVOIRS BY SPONTANEOUS IMBIBITION

    Energy Technology Data Exchange (ETDEWEB)

    Norman R. Morrow

    2004-07-01

    The objective of this project is to increase oil recovery from fractured reservoirs through improved fundamental understanding of the process of spontaneous imbibition by which oil is displaced from the rock matrix into the fractures. Spontaneous imbibition is fundamentally dependent on the reservoir surface free energy but this has never been investigated for rocks. In this project, the surface free energy of rocks will be determined by using liquids that can be solidified within the rock pore space at selected saturations. Thin sections of the rock then provide a two-dimensional view of the rock minerals and the occupant phases. Saturations and oil/rock, water/rock, and oil/water surface areas will be determined by advanced petrographic analysis and the surface free energy which drives spontaneous imbibition will be determined as a function of increase in wetting phase saturation. The inherent loss in surface free energy resulting from capillary instabilities at the microscopic (pore level) scale will be distinguished from the decrease in surface free energy that drives spontaneous imbibition. A mathematical network/numerical model will be developed and tested against experimental results of recovery versus time over broad variation of key factors such as rock properties, fluid phase viscosities, sample size, shape and boundary conditions. Two fundamentally important, but not previously considered, parameters of spontaneous imbibition, the capillary pressure acting to oppose production of oil at the outflow face and the pressure in the nonwetting phase at the no-flow boundary versus time, will also be measured and modeled. Simulation and network models will also be tested against special case solutions provided by analytic models. In the second stage of the project, application of the fundamental concepts developed in the first stage of the project will be demonstrated. The fundamental ideas, measurements, and analytic/numerical modeling will be applied to mixed

  2. Characterizing Fractures Across the Astronaut Corps: Preliminary Findings from Population-Level Analysis

    Science.gov (United States)

    Rossi, Meredith M.; Charvat, Jacqueline; Sibonga, Jean; Sieker, Jeremy

    2017-01-01

    -selection fractures experienced those fractures following their first mission (mean 12.7 +/- 11.1 years following first mission; range 14.0 days - 50.6 years). Additional analyses are ongoing and include examination of fracture history, skeletal site, mechanism, and type of fracture, age at time of fracture, time from spaceflight to fracture, as well as multivariable analysis comparing fracture events to non-events. The results of such analyses may reveal trends in risk factors for fracture among the astronaut corps that have yet to be systematically described through a corps-wide approach.

  3. Sensitivity analysis of a discrete fracture network model for performance assessment of Aberg

    International Nuclear Information System (INIS)

    Outters, N.; Shuttle, D.

    2000-12-01

    This report presents a sensitivity analysis of pathway simulations in a DFN model. The DFN model consists of two sets of stochastic fractures at different scales and the canister locations of a hypothetical repository layout. The hydrogeological base case model is defined by constant head boundary conditions on the edges of a 2000 x 2000 x 1000 m 3 block. The pathway analysis carried out by the program PAWorks provides pathway parameters (pathway length, pathway width, transport aperture, reactive surface area, pathway transmissivity), canister statistics (average number of pathways per canister, percentage of canister locations with pathways) and visualisation of pathways. The project provided the following results from the alternative cases: Case 1: Model with a 100 m thick fracture network at the repository scale instead of 50 m in the base case. The model is little sensitive to the increase of the thickness of the local fracture network. Case 2: Model including fracture networks where the mean size and size standard deviation is twice the ones used in the base case. The travel times to the biosphere is slightly shortened by increasing the fracture diameter. Case 3: Two models with alternative hydraulic boundary conditions: two different flux boundary conditions are tested instead of head boundary conditions in the base case. The advective travel time is shortened by changing the boundary conditions in both alternative cases; in some cases it is reduced to less than a year. Case 4: Study of alternative pathway search algorithms: the pathway search is here based on minimum travel time. The pathway search algorithm of PAWorks based on minimum travel time gives much more optimistic results than the base case where the maximum flow rate was used. The mean travel time is about 5000 years. Due to editorial reasons only a subset of all this information is treated in this report

  4. A New Approach to the Modeling and Analysis of Fracture through Extension of Continuum Mechanics to the Nanoscale

    KAUST Repository

    Sendova, T.

    2010-02-15

    In this paper we focus on the analysis of the partial differential equations arising from a new approach to modeling brittle fracture based on an extension of continuum mechanics to the nanoscale. It is shown that ascribing constant surface tension to the fracture surfaces and using the appropriate crack surface boundary condition given by the jump momentum balance leads to a sharp crack opening profile at the crack tip but predicts logarithmically singular crack tip stress. However, a modified model, where the surface excess property is responsive to the curvature of the fracture surfaces, yields bounded stresses and a cusp-like opening profile at the crack tip. Further, two possible fracture criteria in the context of the new theory are discussed. The first is an energy-based crack growth condition, while the second employs the finite crack tip stress the model predicts. The classical notion of energy release rate is based upon the singular solution, whereas for the modeling approach adopted here, a notion analogous to the energy release rate arises through a different mechanism associated with the rate of working of the surface excess properties at the crack tip. © The Author(s), 2010.

  5. Internal fixation of mandibular angle fractures: a meta-analysis.

    Science.gov (United States)

    Regev, Eran; Shiff, Jacob S; Kiss, Alex; Fialkov, Jeffrey A

    2010-06-01

    The degree of rigidity of internal fixation required for the treatment of mandibular angle fractures has long been at the center of debate in the literature. A statistical comparison between rigid fixation and monocortical fixation has been difficult because of multiple terms, definitions, and technical variations. The purpose of this study was to use the meta-analysis tool to combine information from multiple studies and to compare complication rates for different fixation methods. An English language literature search was conducted for articles on mandibular angle fractures. Information was collected on four variables of interest: compression/noncompression technique, monocortical/bicortical screws, number of plates, and location of plates. Five outcome rates were analyzed: infection, reoperation, hardware removal, malunion, and nonunion. Meta-analyses were run using Comprehensive Meta Analysis, version 2.2.03. Twenty-four studies with relevant data on the variables and outcomes of interest met the inclusion criteria. Significantly higher rates of infection, reoperation, and hardware removal were found for compression compared with noncompression, two plates compared with one plate, and for plates located on both the inferior and superior borders as compared with superior or inferior only. There were also significantly higher infection rates for bicortical screws compared with monocortical screws and higher malunion rates for compression compared with noncompression plating techniques. The results of this meta-analysis found lower complication rates with the use of noncompression, monocortical, and single-plate fixation, supporting the trend toward a single, superiorly placed, monocortical miniplate for fixation of mandibular angle fractures.

  6. Study of Hip Fracture Risk using Tree Structured Survival Analysis

    Directory of Open Access Journals (Sweden)

    Lu Y

    2003-01-01

    Full Text Available In dieser Studie wird das Hüftfraktur-Risiko bei postmenopausalen Frauen untersucht, indem die Frauen in verschiedene Subgruppen hinsichtlich dieses Risikos klassifiziert werden. Frauen in einer gemeinsamen Subgruppe haben ein ähnliches Risiko, hingegen in verschiedenen Subgruppen ein unterschiedliches Hüftfraktur-Risiko. Die Subgruppen wurden mittels der Tree Structured Survival Analysis (TSSA aus den Daten von 7.665 Frauen der SOF (Study of Osteoporosis Fracture ermittelt. Bei allen Studienteilnehmerinnen wurde die Knochenmineraldichte (BMD von Unterarm, Oberschenkelhals, Hüfte und Wirbelsäule gemessen. Die Zeit von der BMD-Messung bis zur Hüftfraktur wurde als Endpunkt notiert. Eine Stichprobe von 75% der Teilnehmerinnen wurde verwendet, um die prognostischen Subgruppen zu bilden (Trainings-Datensatz, während die anderen 25% als Bestätigung der Ergebnisse diente (Validierungs-Datensatz. Aufgrund des Trainings-Datensatzes konnten mittels TSSA 4 Subgruppen identifiziert werden, deren Hüftfraktur-Risiko bei einem Follow-up von im Mittel 6,5 Jahren bei 19%, 9%, 4% und 1% lag. Die Einteilung in die Subgruppen erfolgte aufgrund der Bewertung der BMD des Ward'schen Dreiecks sowie des Oberschenkelhalses und nach dem Alter. Diese Ergebnisse konnten mittels des Validierungs-Datensatzes reproduziert werden, was die Sinnhaftigkeit der Klassifizierungregeln in einem klinischen Setting bestätigte. Mittels TSSA war eine sinnvolle, aussagekräftige und reproduzierbare Identifikation von prognostischen Subgruppen, die auf dem Alter und den BMD-Werten beruhen, möglich. In this paper we studied the risk of hip fracture for post-menopausal women by classifying women into different subgroups based on their risk of hip fracture. The subgroups were generated such that all the women in a particular subgroup had relatively similar risk while women belonging to two different subgroups had rather different risks of hip fracture. We used the Tree Structured

  7. Fracture Analysis of Debonded Sandwich Columns Under Axial Compression

    DEFF Research Database (Denmark)

    May, A.; Avilés, F.; Berggreen, Christian

    A sandwich structure consists of two strong and stiff face sheets bonded to a weak low density core. The large separation between the face sheets provides increased bending rigidity and strength at low weight cost. Thus, sandwich structures frequently present better mechanical properties than...... monolithic structures of the same weight. The vast range of applications of such materials includes wind turbines, marine, and aerospace industries. In this work, geometrically nonlinear finite element analysis is conducted to investigate the fracture parameters and debond propagation of sandwich columns...

  8. Fracture analysis of HFIR beam tube caused by radiation embrittlement

    International Nuclear Information System (INIS)

    Chang, S.J.

    1994-01-01

    With an attempt to estimate the neutron beam tube embrittlement condition for the Oak Ridge High Flux Isotope Reactor (HFIR), fracture mechanics calculations are carried out in this paper. The analysis provides some numerical result on how the tube has been structurally weakened. In this calculation, a lateral impact force is assumed. Numerical result is obtained on how much the critical crack size should be reduced if the beam tube has been subjected to an extended period of irradiation. It is also calculated that buckling strength of the tube is increased, not decreased, with irradiation

  9. Coupled Analysis of Change in Fracture Permeability during the Cooling Phase of the Yucca Mountain Drift Scale Test

    International Nuclear Information System (INIS)

    Rutqvist, Jonny; Rutqvist, J.; Freifeld, B.; Tsang, Y.W.; Min, K.B.; Elsworth, D.

    2008-01-01

    This paper presents results from a coupled thermal, hydrological and mechanical analysis of thermally-induced permeability changes during heating and cooling of fractured volcanic rock at the Drift Scale Test at Yucca Mountain, Nevada. The analysis extends the previous analysis of the four-year heating phase to include newly available data from the subsequent four year cooling phase. The new analysis of the cooling phase shows that the measured changes in fracture permeability follows that of a thermo-hydro-elastic model on average, but at several locations the measured permeability indicates (inelastic) irreversible behavior. At the end of the cooling phase, the air-permeability had decreased at some locations (to as low as 0.2 of initial), whereas it had increased at other locations (to as high as 1.8 of initial). Our analysis shows that such irreversible changes in fracture permeability are consistent with either inelastic fracture shear dilation (where permeability increased) or inelastic fracture surface asperity shortening (where permeability decreased). These data are important for bounding model predictions of potential thermally-induced changes in rock-mass permeability at a future repository at Yucca Mountain

  10. The surface and interior evolution of Ceres revealed by fractures and secondary crater chains

    Science.gov (United States)

    Scully, Jennifer E. C.; Buczkowski, Debra; Schmedemann, Nico; King, Scott; O'Brien, David P.; Castillo-Rogez, Julie; Raymond, Carol; Marchi, Simone; Russell, Christopher T.; Mitri, Giuseppe; Bland, Michael T.

    2016-10-01

    Dawn became the first spacecraft to visit and orbit Ceres, a dwarf planet and the largest body in the asteroid belt (radius ~470 km) (Russell et al., 2016). Before Dawn's arrival, telescopic observations and thermal evolution modeling indicated Ceres was differentiated, with an average density of 2,100 kg/m3 (e.g. McCord & Sotin, 2005; Castillo-Rogez & McCord, 2010). Moreover, pervasive viscous relaxation in a water-ice-rich outer layer was predicted to erase most features on Ceres' surface (Bland, 2013). However, a full understanding of Ceres' surface and interior evolution remained elusive. On the basis of global geologic mapping, we identify prevalent ≥1 km wide linear features that formed: 1) as the surface expression of subsurface fractures, and 2) as material ejected during impact-crater formation impacted and scoured the surface, forming secondary crater chains. The formation and preservation of these linear features indicates Ceres' outer layer is relatively strong, and is not dominated by viscous relaxation as predicted. The fractures also give us insights into Ceres' interior: their spacing indicates the fractured layer is ~30 km thick, and we interpret the fractures formed because of uplift and extension induced by an upwelling region, which is consistent with geodynamic modeling (King et al., 2016). In addition, we find that some secondary crater chains do not form radial patterns around their source impact craters, and are located in a different hemisphere from their source impact craters, because of Ceres' fast rotation (period of ~9 hours) and relatively small radius. Our results show Ceres has a surface and outer layer with characteristics that are different than predicted, and underwent complex surface and interior evolution. Our fuller understanding of Ceres, based on Dawn data, gives us important insights into the evolution of bodies in the asteroid belt, and provides unique constraints that can be used to evaluate predictions of the surface

  11. On the mechanical interaction between a fluid-filled fracture and the earth's surface

    Science.gov (United States)

    Pollard, D.D.; Holzhausen, G.

    1979-01-01

    The mechanical interaction between a fluid-filled fracture (e.g., hydraulic fracture joint, or igneous dike) and the earth's surface is analyzed using a two-dimensional elastic solution for a slit of arbitrary inclination buried beneath a horizontal free surface and subjected to an arbitrary pressure distribution. The solution is obtained by iteratively superimposing two fundamental sets of analytical solutions. For uniform internal pressure the slit behaves essentially as if it were in an infinite region if the depth-to-center is three times greater than the half-length. For shallower slits interaction with the free surface is pronounced: stresses and displacements near the slit differ by more than 10% from values for the deeply buried slit. The following changes are noted as the depth-to-center decreases: 1. (1) the mode I stress intensity factor increases for both ends of the slit, but more rapidly at the upper end; 2. (2) the mode II stress-intensity factor is significantly different from zero (except for vertical slits) suggesting propagation out of the original plane of the slit; 3. (3) displacements of the slit wall are asymmetric such that the slit gaps open more widely near the upper end. Similar changes are noted if fluid density creates a linear pressure gradient that is smaller than the lithostatic gradient. Under such conditions natural fractures should propagate preferentially upward toward the earth's surface requiring less pressure as they grow in length. If deformation near the surface is of interest, the model should account explicitly for the free surface. Stresses and displacements at the free surface are not approximated very well by values calculated along a line in an infinite region, even when the slit is far from the line. As depth-to-center of a shallow pressurized slit decreases, the following changes are noted: 1. (1) displacements of the free surface increase to the same order of magnitude as the displacements of the slit walls, 2. (2

  12. High volume hydraulic fracturing operations: potential impacts on surface water and human health.

    Science.gov (United States)

    Mrdjen, Igor; Lee, Jiyoung

    2016-08-01

    High volume, hydraulic fracturing (HVHF) processes, used to extract natural gas and oil from underground shale deposits, pose many potential hazards to the environment and human health. HVHF can negatively affect the environment by contaminating soil, water, and air matrices with potential pollutants. Due to the relatively novel nature of the process, hazards to surface waters and human health are not well known. The purpose of this article is to link the impacts of HVHF operations on surface water integrity, with human health consequences. Surface water contamination risks include: increased structural failure rates of unconventional wells, issues with wastewater treatment, and accidental discharge of contaminated fluids. Human health risks associated with exposure to surface water contaminated with HVHF chemicals include increased cancer risk and turbidity of water, leading to increased pathogen survival time. Future research should focus on modeling contamination spread throughout the environment, and minimizing occupational exposure to harmful chemicals.

  13. Fracture-free surfaces of CAD/CAM lithium metasilicate glass-ceramic using micro-slurry jet erosion.

    Science.gov (United States)

    Yin, Ling; Baba, Takashi; Nakanishi, Yoshitaka

    2018-04-01

    This paper reports the use of micro-slurry jet erosion (MSJE) on CAD/CAM lithium mesilicate glass ceramic (LMGC) that is capable of achieving the fracture-free surface quality. A computer-controlled MSJE process using a low-pressure and low-concentration alumina slurry was applied to diamond-ground LMGC surfaces with surface and subsurface damage. The MSJE processed and diamond-ground LMGC surfaces were examined using scanning electron microscopy (SEM) to examine surface morphology, fractures, and residual defects. 3D confocal laser microscopy (CLM) was used to quantitatively characterize all machined surface textures as a function of processing conditions. Our results show that surface and subsurface damage induced in diamond-ground surfaces were significantly diminished after 50-cycle MSJE processing. Fracture-free surfaces were obtained after 100 MSJE cycles. Our measured parameters of the 3D surface topography included the average surface roughness, maximum peak-valley height, highest peak height, lowest valley height, and kurtosis and absolute skewness of height distributions. All these parameters were significantly reduced with the increase of MSJE cycles. This work implies that MSJE promises to be an effective manufacturing technique for the generation of fracture-free LMGC surfaces which are crucial for high-quality monolithic restorations made from the material. Copyright © 2018 Elsevier Ltd. All rights reserved.

  14. Technology development on analysis program for measuring fracture toughness of irradiated specimens

    International Nuclear Information System (INIS)

    Shibata, Akira; Takada, Fumiki

    2007-03-01

    The fracture toughness which represents resistance for brittle or ductile fracture is one of the most important material property concerning linear and non-linear fracture mechanics analyses. In order to respond to needs of collecting data relating to fracture toughness of pressure vessel and austenitic stainless steels, fracture toughness test for irradiated materials has been performed in JMTR hot laboratory. On the other hand, there has been no computer program for analysis of fracture toughness using the test data obtained from the test apparatus installed in the hot cell. Therefore, only load-displacement data have been provided to users to calculate fracture toughness of irradiated materials. Recently, request of analysis of fracture toughness have been increased. Thus a computer program, which calculates the amount of the crack extension, the compliance and the fracture toughness from the data acquired from the test apparatus installed in the hot cell, has been developed. In the program unloading elastic compliance method is applied based on ASTM E1820-01. Through the above development, the request for the fracture toughness analysis can be satisfied and the fracture toughness of irradiated test specimens can be provided to users. (author)

  15. Fracture analysis of axially cracked pressure tube of pressurized heavy water reactor

    International Nuclear Information System (INIS)

    Krishnan, S.; Bhasin, V.; Mahajan, S.C.

    1997-01-01

    Three Dimensional (313) finite element elastic plastic fracture analysis was done for through wall axially cracked thin pressure tubes of 220 MWe Indian Pressurized Heavy Water Reactor. The analysis was done for Zr-2 and Zr-2.5Nb pressure tubes operating at 300 degrees C and subjected to 9.5 Mpa internal pressure. Critical crack length was determined based on tearing instability concept. The analysis included the effect of crack face pressure due to the leaking fluid from tube. This effect was found to be significant for pressure tubes. The available formulae for calculating J (for axially cracked tubes) do not take into account the effect of crack face pressure. 3D finite element analysis also gives insight into variation of J across the thickness of pressure tube. It was observed that J is highest at the mid-surface of tube. The results have been presented in the form of across the thickness average J value and a peak factor on J. Peak factor on J is ratio of J at mid surface to average J value. Crack opening area for different cracked lengths was calculated from finite element results. The fracture assessment of pressure tubes was also done using Central Electricity Generating Board R-6 method. Ductile tearing was considered

  16. Fracture analysis of axially cracked pressure tube of pressurized heavy water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Krishnan, S.; Bhasin, V.; Mahajan, S.C. [Bhabha Atomic Research Centre, Bombay (India)] [and others

    1997-04-01

    Three Dimensional (313) finite element elastic plastic fracture analysis was done for through wall axially cracked thin pressure tubes of 220 MWe Indian Pressurized Heavy Water Reactor. The analysis was done for Zr-2 and Zr-2.5Nb pressure tubes operating at 300{degrees}C and subjected to 9.5 Mpa internal pressure. Critical crack length was determined based on tearing instability concept. The analysis included the effect of crack face pressure due to the leaking fluid from tube. This effect was found to be significant for pressure tubes. The available formulae for calculating J (for axially cracked tubes) do not take into account the effect of crack face pressure. 3D finite element analysis also gives insight into variation of J across the thickness of pressure tube. It was observed that J is highest at the mid-surface of tube. The results have been presented in the form of across the thickness average J value and a peak factor on J. Peak factor on J is ratio of J at mid surface to average J value. Crack opening area for different cracked lengths was calculated from finite element results. The fracture assessment of pressure tubes was also done using Central Electricity Generating Board R-6 method. Ductile tearing was considered.

  17. Stresses, fatigue and fracture analysis in the tube sheets

    International Nuclear Information System (INIS)

    Billon, F.

    1986-05-01

    The purpose of the present work is to study the behaviour of the nuclear PWR steam generator tube sheet. But the methods developed in this field can easily be generalized in order to study tube sheets from any other type of heat exchangers. The aim of the stress analysis of these sheets is to verify their correct design, to quantify the risk of fatigue damage in the areas submitted to a high stress concentration and through the fracture mechanic, to make sure there is no risk of fast fracture resulting from initiated or pre-existing defects. This analysis necessarily relates to the calculation of stresses in all parts of the multidrilled area, mainly around the holes where they are concentrated. However the tube sheets are so complexe structures that their direct modelization cannot be envisaged within the context of the finite element method. We then must refer to the concept of equivalent medium in order to calculate the nominal stresses. Then using the stresses multiple fonctions appropriate to the net geometry, we can calculate the actual stresses concentrated around the holes. The method depends on the behaviour of the elementary volume which represents the behaviour of the multidrilled medium. This approach must allow to correctly take account of the ''thermal skin effect'', which is a phenomenon particular to the tube sheets with thermal loads. It must as well be generalized in order to analyse the irregular ligaments which affect the periodical stresses distribution and locally overconcentrate them [fr

  18. Cause analysis of missing diagnosis for vertebral fracture on lateral chest radiography

    International Nuclear Information System (INIS)

    Yu Wei; Yao Jinpeng; Lin Qiang; Mu Wenbin

    2010-01-01

    Objective: To analyze the cause of missing diagnosis for vertebral fracture on lateral chest radiography. Methods: Lateral chest radiographies of 1638 hospitalized patients (871 males and 767 females) were retrospectively reviewed for identifying vertebral fractures. Their ages ranged from 50 to 91 years with the mean of 63.5 years. Complains and application for chest radiography in all patients were not related to osteoporosis and vertebral fracture. Vertebral fracture and fracture severity were evaluated using Genant's semiquantitative visual method, taking approximately a 20%-25% vertebral height reduction as mild grade, 26%--40% as moderate grade and 41% or greater as severe grade. Evaluation results of the vertebral fracture, original X-ray reports, as well as medical records were compared for further analysis. Results: Eighty-four in 1638 patients showed vertebral fractures on the lateral chest radiographies. Of them, vertebral fractures were reported in 30 cases and 54 patients were not reported on their original X-ray reports. There were 63 vertebral fractures in 54 un-reported patients, most of which were single fracture (75% or 47/63). Grade I fracture accounted for 54% (34/63), Grade II fracture 33% (21/63), while 13% presented grade III fracture (8/63). In all 84 patients with vertebral fractures, only 5 cases (6%) underwent dual energy X-ray absorptiometry (DXA) measurement, 5 cases (6%) were recorded to have vertebral fractures on the medical papers, as well as 15 cases (18%) were prescribed drugs related to the osteoporosis when discharged from hospital. All drugs prescribed for the 15 patients were limited only to calcium. Conclusions: More attention should be paid to osteoporosis by doctors including radiologists. Vertebral fracture on lateral chest radiography should be completely diagnosed, which is helpful for both prevention and treatment. (authors)

  19. An analysis of 214 cases of rib fractures

    OpenAIRE

    Karadayi, Sule; Nadir, Aydin; Sahin, Ekber; Celik, Burcin; Arslan, Sulhattin; Kaptanoglu, Melih

    2011-01-01

    INTRODUCTION: Rib fractures are the most common type of injury associated with trauma to the thorax. In this study, we investigated whether morbidity and mortality rates increased in correlation with the number of fractured ribs. MATERIALS AND METHODS: Data from 214 patients with rib fractures who applied or were referred to our clinic between January 2007 and December 2008 were retrospectively evaluated. The patients were allocated into three groups according to the number of fractures: 1) p...

  20. Early Weightbearing After Operatively Treated Ankle Fractures: A Biomechanical Analysis.

    Science.gov (United States)

    Tan, Eric W; Sirisreetreerux, Norachart; Paez, Adrian G; Parks, Brent G; Schon, Lew C; Hasenboehler, Erik A

    2016-06-01

    No consensus exists regarding the timing of weightbearing after surgical fixation of unstable traumatic ankle fractures. We evaluated fracture displacement and timing of displacement with simulated early weightbearing in a cadaveric model. Twenty-four fresh-frozen lower extremities were assigned to Group 1, bimalleolar ankle fracture (n=6); Group 2, trimalleolar ankle fracture with unfixed small posterior malleolar fracture (n=9); or Group 3, trimalleolar ankle fracture with fixed large posterior malleolar fracture (n=9) and tested with axial compressive load at 3 Hz from 0 to 1000 N for 250 000 cycles to simulate 5 weeks of full weightbearing. Displacement was measured by differential variable reluctance transducer. The average motion at all fracture sites in all groups was significantly less than 1 mm (P fracture was 0.1±0.1 mm and 0.4±0.4 mm, respectively. Group 2 displacement of the lateral, medial, and posterior malleolar fracture was 0.6±0.4 mm, 0.5±0.4 mm, and 0.5±0.6 mm, respectively. Group 3 displacement of the lateral, medial, and posterior malleolar fracture was 0.1±0.1 mm, 0.5±0.7 mm, and 0.5±0.4 mm, respectively. The majority of displacement (64.0% to 92.3%) occurred in the first 50 000 cycles. There was no correlation between fracture displacement and bone mineral density. No significant fracture displacement, no hardware failure, and no new fractures occurred in a cadaveric model of early weightbearing in unstable ankle fracture after open reduction and internal fixation. This study supports further investigation of early weightbearing postoperative protocols after fixation of unstable ankle fractures. © The Author(s) 2016.

  1. Fragility Fracture Incidence in Chronic Obstructive Pulmonary Disease (COPD) Patients Associates With Nanoporosity, Mineral/Matrix Ratio, and Pyridinoline Content at Actively Bone-Forming Trabecular Surfaces.

    Science.gov (United States)

    Paschalis, Eleftherios P; Gamsjaeger, Sonja; Dempster, David; Jorgetti, Vanda; Borba, Victoria; Boguszewski, Cesar L; Klaushofer, Klaus; Moreira, Carolina A

    2017-01-01

    Chronic obstructive pulmonary disease (COPD) is associated with low areal bone mineral density (aBMD) by dual-energy X-ray absorptiometry (DXA) and altered microstructure by bone histomorphometry and micro-computed tomography. Nevertheless, not all COPD patients sustain fragility fractures. In the present study, we used Raman microspectroscopic analysis to determine bone compositional properties at actively forming trabecular surfaces (based on double fluorescent labels) in iliac crest biopsies from 19 postmenopausal COPD patients (aged 62.1 ± 7.3 years). Additionally, we analyzed trabecular geometrical centers, representing tissue much older than the forming surfaces. Eight of the patients had sustained fragility fractures, and 13 had received treatment with inhaled glucocorticoids. None of the patients had taken oral glucocorticoids. The monitored parameters were mineral/matrix ratio (MM), nanoporosity, and relative glycosaminoglycan (GAG), lipid, and pyridinoline contents (PYD). There were no significant differences between the glucocorticoid-treated patients and those who did not receive any. On the other hand, COPD patients sustaining fragility fractures had significantly lower nanoporosity and higher MM and PYD values compared with COPD patients without fragility fractures. To the best of our knowledge, this is the first study to discriminate between fracture and non-fracture COPD patients based on differences in the material properties of bone matrix. Given that these bone material compositional differences are evident close to the cement line (a major bone interface), they may contribute to the inferior bone toughness and coupled with the lower lumbar spine bone mineral density values result in the fragility fractures prevalent in these patients. © 2016 American Society for Bone and Mineral Research. © 2016 American Society for Bone and Mineral Research.

  2. Correlation between Fatigue Crack Growth Behavior and Fracture Surface Roughness on Cold-Rolled Austenitic Stainless Steels in Gaseous Hydrogen

    Directory of Open Access Journals (Sweden)

    Tai-Cheng Chen

    2018-03-01

    Full Text Available Austenitic stainless steels are often considered candidate materials for use in hydrogen-containing environments because of their low hydrogen embrittlement susceptibility. In this study, the fatigue crack growth behavior of the solution-annealed and cold-rolled 301, 304L, and 310S austenitic stainless steels was characterized in 0.2 MPa gaseous hydrogen to evaluate the hydrogen-assisted fatigue crack growth and correlate the fatigue crack growth rates with the fracture feature or fracture surface roughness. Regardless of the testing conditions, higher fracture surface roughness could be obtained in a higher stress intensity factor (∆K range and for the counterpart cold-rolled specimen in hydrogen. The accelerated fatigue crack growth of 301 and 304L in hydrogen was accompanied by high fracture surface roughness and was associated with strain-induced martensitic transformation in the plastic zone ahead of the fatigue crack tip.

  3. Temporal moment analysis of solute transport in a coupled fracture ...

    Indian Academy of Sciences (India)

    by considering an inlet boundary condition of constant continuous source in a single fracture. The effect of various fracture-skin parameters like porosity, thickness and ... Study on fluid flow and transport of solute through fractures has been an .... of solutes is happening normal to the direction of flow due to the free molecular.

  4. Analysis of 213 currently used rehabilitation protocols in foot and ankle fractures.

    Science.gov (United States)

    Pfeifer, Christian G; Grechenig, Stephan; Frankewycz, Borys; Ernstberger, Antonio; Nerlich, Michael; Krutsch, Werner

    2015-10-01

    Fractures of the ankle, hind- and midfoot are amongst the five most common fractures. Besides initial operative or non-operative treatment, rehabilitation of the patients plays a crucial role for fracture union and long term functional outcome. Limited evidence is available with regard to what a rehabilitation regimen should include and what guidelines should be in place for the initial clinical course of these patients. This study therefore investigated the current rehabilitation concepts after fractures of the ankle, hind- and midfoot. Written rehabilitation protocols provided by orthopedic and trauma surgery institutions in terms of recommendations for weight bearing, range of motion (ROM), physiotherapy and choice of orthosis were screened and analysed. All protocols for lateral ankle fractures type AO 44A1, AO 44B1 and AO 44C1, for calcaneal fractures and fractures of the metatarsal as well as other not specific were included. Descriptive analysis was carried out and statistical analysis applied where appropriate. 209 rehabilitation protocols for ankle fractures type AO 44B1 and AO 44C1, 98 for AO 44A1, 193 for metatarsal fractures, 142 for calcaneal fractures, 107 for 5(th) metatarsal base fractures and 70 for 5(th) metatarsal Jones fractures were evaluated. The mean time recommended for orthosis treatment was 6.04 (SD 0.04) weeks. While the majority of protocols showed a trend towards increased weight bearing and increased ROM over time, the best consensus was noted for weight bearing recommendations. Our study shows that there exists a huge variability in rehabilitation of fractures of the ankle-, hind- and midfoot. This may be contributed to a lack of consensus (e.g. missing publication of guidelines), individualized patient care (e.g. in fragility fractures) or lack of specialization. This study might serve as basis for prospective randomized controlled trials in order to optimize rehabilitation for these common fractures. Copyright © 2015 Elsevier Ltd

  5. Research on fracture analysis, groundwater flow and sorption processes in fractured rocks

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dae Ha [Korea Institute of Geology Mining and Materials, Taejon (Korea)

    1998-12-01

    Due to increasing demand for numerous industrial facilities including nuclear power plants and waste repositories, the feasibility of rocks masses as sites for the facilities has been a geological issue of concern. Rock masses, in general, comprises systems of fractures which can provide pathways for groundwater flow and may also affect the stability of engineered structures. such properties of fractures stimulate a synthetic study on (1) analyses of fracture systems, and (2) characterization of groundwater flow and sorption processes in fractured rocks to establish a preliminary model for assessing suitable sites for industrial facilities. The analyses of fracture systems cover (1) reconstruction of the Cenozoic tectonic movements and estimation of frequency indices for the Holocene tectonic movements, (2) determination of distributions and block movements of the Quaternary marine terraces, (3) investigation of lithologic and geotechnical nature of study area, and (4) examination of the Cenozoic volcanic activities and determination of age of the dike swarms. Using data obtained from above mentioned analyses along with data related to earthquakes and active faults, probabilistic approach is performed to determine various potential hazards which may result from the Quaternary or the Holocene tectonic movements. In addition, stepwise and careful integration of various data obtained from field works and laboratory experiments are carried out to analyze groundwater flow in fractures rocks as follows; (1) investigation of geological feature of the site, (2) identification and characterization of fracture systems using core and televiewer logs, (3) determination of conductive fractures using electrical conductivity, temperature, and flow logs, (4) identification of hydraulic connections between fractures using televiewer logs with tracer tests within specific zones. The results obtained from these processes allow a qualitative interpretation of groundwater flow patterns

  6. Tensile toughness test and high temperature fracture analysis of thermal barrier coatings

    International Nuclear Information System (INIS)

    Qian, G.; Nakamura, T.; Berndt, C.C.; Leigh, S.H.

    1997-01-01

    In this paper, an effective fracture toughness test which uses interface fracture mechanics theory is introduced. This method is ideally suited for determining fracture resistance of multilayered thermal barrier coatings (TBCs) consisting of ceramic and bond layers and, unlike other fracture experiments, requires minimal set-up over a simple tensile adhesion test. Furthermore, while other test methods usually use edge cracked specimens, the present test models a crack embedded within the coatings, which is more consistent with actual TBCs where failure initiates from internal voids or defects. The results of combined computational and experimental analysis show that any defects located within the ceramic coating can significantly weaken a TBC, whereas the debonding resistances of the bond coating and its interfaces are found to be much higher. In a separate analysis, the authors have studied fracture behavior of TBCs subjected to thermal loading in a high temperature environment. The computed fracture parameters reveal that when the embedded crack size is on order of the coating thickness, the fracture driving force is comparable to the fracture resistance of the coating found in the toughness test. In addition, the major driving force for fracture derives from the thermal insulating effect across the crack faces rather than the mismatch in the coefficients of thermal expansion. The authors have also investigated the effects of functionally graded material (FGM) within TBCs and found its influences on the fracture parameters to be small. This result implies that the FGM may not contribute toward enhancing the fracture toughness of the TBCs considered here

  7. An analysis of fracture trace patterns in areas of flat-lying sedimentary rocks for the detection of buried geologic structure. [Kansas and Texas

    Science.gov (United States)

    Podwysocki, M. H.

    1974-01-01

    Two study areas in a cratonic platform underlain by flat-lying sedimentary rocks were analyzed to determine if a quantitative relationship exists between fracture trace patterns and their frequency distributions and subsurface structural closures which might contain petroleum. Fracture trace lengths and frequency (number of fracture traces per unit area) were analyzed by trend surface analysis and length frequency distributions also were compared to a standard Gaussian distribution. Composite rose diagrams of fracture traces were analyzed using a multivariate analysis method which grouped or clustered the rose diagrams and their respective areas on the basis of the behavior of the rays of the rose diagram. Analysis indicates that the lengths of fracture traces are log-normally distributed according to the mapping technique used. Fracture trace frequency appeared higher on the flanks of active structures and lower around passive reef structures. Fracture trace log-mean lengths were shorter over several types of structures, perhaps due to increased fracturing and subsequent erosion. Analysis of rose diagrams using a multivariate technique indicated lithology as the primary control for the lower grouping levels. Groupings at higher levels indicated that areas overlying active structures may be isolated from their neighbors by this technique while passive structures showed no differences which could be isolated.

  8. Surgical interventions to treat humerus shaft fractures: A network meta-analysis of randomized controlled trials.

    Directory of Open Access Journals (Sweden)

    Jia-Guo Zhao

    Full Text Available There are three main surgical techniques to treat humeral shaft fractures: open reduction and plate fixation (ORPF, intramedullary nail (IMN fixation, and minimally invasive percutaneous osteosynthesis (MIPO. We performed a network meta-analysis to compare three surgical procedures, including ORPF, IMN fixation, and MIPO, to provide the optimum treatment for humerus shaft fractures.MEDLINE, EMBASE, Cochrane Bone, Joint and Muscle Trauma Group Specialised Register, and Cochrane library were researched for reports published up to May 2016. We only included randomized controlled trials (RCTs comparing two or more of the three surgical procedures, including the ORPF, IMN, and MIPO techniques, for humeral shaft fractures in adults. The methodological quality was evaluated based on the Cochrane risk of bias tool. We used WinBUGS1.4 to conduct this Bayesian network meta-analysis. We used the odd ratios (ORs with 95% confidence intervals (CIs to calculate the dichotomous outcomes and analyzed the percentages of the surface under the cumulative ranking curve.Seventeen eligible publications reporting 16 RCTs were included in this study. Eight hundred and thirty-two participants were randomized to receive one of three surgical procedures. The results showed that shoulder impingement occurred more commonly in the IMN group than with either ORPF (OR, 0.13; 95% CI, 0.03-0.37 or MIPO fixation (OR, 0.08; 95% CI, 0.00-0.69. Iatrogenic radial nerve injury occurred more commonly in the ORPF group than in the MIPO group (OR, 11.09; 95% CI, 1.80-124.20. There were no significant differences among the three procedures in nonunion, delayed union, and infection.Compared with IMN and ORPF, MIPO technique is the preferred treatment method for humeral shaft fractures.

  9. Plastic fracture instability analysis of wall breakthrough in a circumferentially cracked pipe subjected to bending loads

    International Nuclear Information System (INIS)

    Zahoor, A.; Kanninen, M.F.

    1981-01-01

    A method of analyzing internal surface circumferential cracks in ductile reactor piping is presented. The method utilizes an alternate but equivalent definition of the J-integral based on nonlinear structural compliance. The analysis is valid for situations where the cross section containing the crack is fully yielded. Results are obtained for radial and circumferential crack growth for pipes subjected to bending. The stability of radial crack growth (wall breakthrough) is assessed using the J-integral-based tearing modulus approach. The analysis is shown to be in agreement with experimental results on the stability of surface crack growth in Type 304 stainless stee pipes. Example quantitative results for fracture instability assessments for nuclear piping are presented. 23 refs

  10. Plastic fracture instability analysis of wall breakthrough in a circumferentially cracked pipe subjected to bending loads

    Energy Technology Data Exchange (ETDEWEB)

    Zahoor, A.; Kanninen, M.F.

    1981-07-01

    A method of analyzing internal surface circumferential cracks in ductile reactor piping is presented. The method utilizes an alternate but equivalent definition of the J-integral based on nonlinear structural compliance. The analysis is valid for situations where the cross section containing the crack is fully yielded. Results are obtained for radial and circumferential crack growth for pipes subjected to bending. The stability of radial crack growth (wall breakthrough) is assessed using the J-integral-based tearing modulus approach. The analysis is shown to be in agreement with experimental results on the stability of surface crack growth in Type 304 stainless stee pipes. Example quantitative results for fracture instability assessments for nuclear piping are presented. 23 refs.

  11. Analysis on the risk factors of second fracture in osteoporosis-

    Directory of Open Access Journals (Sweden)

    RUAN Wen-dong

    2011-04-01

    Full Text Available 【Abstract】 Objective: To explore the clinical characteristics and risk factors of refracture in patients suffering from osteoporosis-related fractures as well as effective interventions. Methods: From January 2006 to January 2008, both out-patients and in-patients in our hospital who were over 50 years old and suffered from osteoporosis-related fractures were selected for this research. They were divided into fracture group and refracture group. The refracture rate was followed up for 2 years, during which 11 patients developed refracture, thus were included in the refracture group. Therefore, 273 patients, 225 first-fracture cases, aged (67.7± 8.5 years, and 48 refracture cases, aged (72.7±9.5 years, were included in this study. General data including age and sex, fracture types, femoral neck bone mineral density (BMD T-scores tested by dual-energy X-rays absorptiometry (DEXA, Charlson index, time-frame between two fractures as well as mobility skill assessment were collected and analyzed by single-factor and multivariate statistical methods. Results: Females accounted for 70.2% of the fracture group and 77.1% of the refracture group. The most common refracture type was vertebral fracture for the first time and femoral neck fracture for the second time during the followup. The second fracture happened 3.7 years after the first one on average. The refracture rate was 2.12% within one year, and 4.66% within two years. Risk factors for a second fracture in osteoporotic fracture patients included age (>75 years, HR=1.23, 95%CI 1.18-1.29; >85 years, HR=1.68, 95% CI 1.60-1.76, female sex (HR=1.36, 95%CI 1.32-1.40, prior vertebral fractures (HR=1.62, 95%CI 1.01-2.07, prior hip fractures (HR=1.27, 95%CI 0.89-2.42, BMD T-score<-3.5 (HR=1.38, 95%CI 1.17-1.72 and weakened motor skills (HR=1.27, 95%CI 1.09-1.40. Conclusions: The risks of second fracture among patients with initial brittle fracture are substantial. There is adequate time between the

  12. Visualization and Hierarchical Analysis of Flow in Discrete Fracture Network Models

    Science.gov (United States)

    Aldrich, G. A.; Gable, C. W.; Painter, S. L.; Makedonska, N.; Hamann, B.; Woodring, J.

    2013-12-01

    Flow and transport in low permeability fractured rock is primary in interconnected fracture networks. Prediction and characterization of flow and transport in fractured rock has important implications in underground repositories for hazardous materials (eg. nuclear and chemical waste), contaminant migration and remediation, groundwater resource management, and hydrocarbon extraction. We have developed methods to explicitly model flow in discrete fracture networks and track flow paths using passive particle tracking algorithms. Visualization and analysis of particle trajectory through the fracture network is important to understanding fracture connectivity, flow patterns, potential contaminant pathways and fast paths through the network. However, occlusion due to the large number of highly tessellated and intersecting fracture polygons preclude the effective use of traditional visualization methods. We would also like quantitative analysis methods to characterize the trajectory of a large number of particle paths. We have solved these problems by defining a hierarchal flow network representing the topology of particle flow through the fracture network. This approach allows us to analyses the flow and the dynamics of the system as a whole. We are able to easily query the flow network, and use paint-and-link style framework to filter the fracture geometry and particle traces based on the flow analytics. This allows us to greatly reduce occlusion while emphasizing salient features such as the principal transport pathways. Examples are shown that demonstrate the methodology and highlight how use of this new method allows quantitative analysis and characterization of flow and transport in a number of representative fracture networks.

  13. Outcrop-scale fracture trace identification using surface roughness derived from a high-density point cloud

    Science.gov (United States)

    Okyay, U.; Glennie, C. L.; Khan, S.

    2017-12-01

    Owing to the advent of terrestrial laser scanners (TLS), high-density point cloud data has become increasingly available to the geoscience research community. Research groups have started producing their own point clouds for various applications, gradually shifting their emphasis from obtaining the data towards extracting more and meaningful information from the point clouds. Extracting fracture properties from three-dimensional data in a (semi-)automated manner has been an active area of research in geosciences. Several studies have developed various processing algorithms for extracting only planar surfaces. In comparison, (semi-)automated identification of fracture traces at the outcrop scale, which could be used for mapping fracture distribution have not been investigated frequently. Understanding the spatial distribution and configuration of natural fractures is of particular importance, as they directly influence fluid-flow through the host rock. Surface roughness, typically defined as the deviation of a natural surface from a reference datum, has become an important metric in geoscience research, especially with the increasing density and accuracy of point clouds. In the study presented herein, a surface roughness model was employed to identify fracture traces and their distribution on an ophiolite outcrop in Oman. Surface roughness calculations were performed using orthogonal distance regression over various grid intervals. The results demonstrated that surface roughness could identify outcrop-scale fracture traces from which fracture distribution and density maps can be generated. However, considering outcrop conditions and properties and the purpose of the application, the definition of an adequate grid interval for surface roughness model and selection of threshold values for distribution maps are not straightforward and require user intervention and interpretation.

  14. Plastic fracture mechanics prediction of fracture instability in a circumferentially cracked pipe in bending--1. J-integral analysis

    International Nuclear Information System (INIS)

    Zahoor, A.; Kanninen, M.F.

    1980-01-01

    A method of evaluating the J-integral for a circumferentially cracked pipe in bending is proposed. The method allows a J-resistance curve to be evaluated directly from the load-displacement record obtained in a pipe fracture experiment. This method also permits an analysis for fracture instability in a circumferential crack growth using a J-resistance curve and the tearing modulus parameter. The importance of using a J-resistance curve that is consistent with the type of constraint for a given application is emphasized. 18 refs

  15. Fatigue Fracture Characteristics of Ti6Al4V Subjected to Ultrasonic Nanocrystal Surface Modification

    Directory of Open Access Journals (Sweden)

    Xiaojian Cao

    2018-01-01

    Full Text Available The influence of ultrasonic nanocrystal surface modification (UNSM on the fatigue fracture characteristics of Ti6Al4V was investigated. Two groups of specimens were separated due to different heat treatment conditions. Group one was stress-relief annealed at 650 °C, and group two was then treated with solid solution-aging. UNSM with the conditions of a static load of 25 N, vibration amplitude of 30 μm, and 36,000 strikes per unit produced about 40 μm surface severe plastic deformation (SPD layers on both groups of specimens. UNSM improved the microhardness and the compressive residual stress. UNSM also helped achieve a neat surface, almost without changing the surface roughness. The fatigue strengths of these two groups were improved by 7% and 11.7%, respectively. After UNSM, fatigue cracks mainly initiated from the surface of the specimen before the fatigue life of 106 cycles, while they appeared at the internal compress deformed α-phase at the zone between the SPD layer and the core after the fatigue life of 106 cycles. The cracks usually extended along the deformation overflow bands and the process traces on the surface. Through the change of micro-dimples in the fatigue final rupture region, nanocrystals were achieved in the SPD layer. The crystal slip and the surface remodeling together influenced the energy field of crack evolution.

  16. Pressurized thermal shock probabilistic fracture mechanics sensitivity analysis for Yankee Rowe reactor pressure vessel

    International Nuclear Information System (INIS)

    Dickson, T.L.; Cheverton, R.D.; Bryson, J.W.; Bass, B.R.; Shum, D.K.M.; Keeney, J.A.

    1993-08-01

    The Nuclear Regulatory Commission (NRC) requested Oak Ridge National Laboratory (ORNL) to perform a pressurized-thermal-shock (PTS) probabilistic fracture mechanics (PFM) sensitivity analysis for the Yankee Rowe reactor pressure vessel, for the fluences corresponding to the end of operating cycle 22, using a specific small-break-loss- of-coolant transient as the loading condition. Regions of the vessel with distinguishing features were to be treated individually -- upper axial weld, lower axial weld, circumferential weld, upper plate spot welds, upper plate regions between the spot welds, lower plate spot welds, and the lower plate regions between the spot welds. The fracture analysis methods used in the analysis of through-clad surface flaws were those contained in the established OCA-P computer code, which was developed during the Integrated Pressurized Thermal Shock (IPTS) Program. The NRC request specified that the OCA-P code be enhanced for this study to also calculate the conditional probabilities of failure for subclad flaws and embedded flaws. The results of this sensitivity analysis provide the NRC with (1) data that could be used to assess the relative influence of a number of key input parameters in the Yankee Rowe PTS analysis and (2) data that can be used for readily determining the probability of vessel failure once a more accurate indication of vessel embrittlement becomes available. This report is designated as HSST report No. 117

  17. Research on fracture analysis, groundwater flow and sorption processes in fractured rocks

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dae-Ha; Kim, Won-Young; Lee, Seung-Gu [Korea Institute of Geology Mining and Materials, Taejon (KR)] (and others)

    1999-12-01

    Due to increasing demand for numerous industrial facilities including nuclear power plants and waste repositories, the feasibility of rocks masses as sites for the facilities has been a geological issue of concern. Rock masses, in general, comprises systems of fractures which can provide pathways for groundwater flow and may also affect the stability of engineered structures. For the study of groundwater flow and sorption processes in fractured rocks, five boreholes were drilled. A stepwise and careful integration of various data obtained from field works and laboratory experiments were carried out to analyze groundwater flow in fractured rocks as follows; (1) investigation of geological feature of the site, (2) identification and characterization of fracture systems using core and televiewer logs, (3) determination of hydrogeological properties of fractured aquifers using geophysical borehole logging, pumping and slug tests, and continuous monitoring of groundwater level and quality, (4) evaluation of groundwater flow patterns using fluid flow modeling. The results obtained from these processes allow a qualitative interpretation of fractured aquifers in the study area. Column experiments of some reactive radionuclides were also performed to examine sorption processes of the radionuclides including retardation coefficients. In addition, analyses of fracture systems covered (1) reconstruction of the Cenozoic tectonic movements and estimation of frequency indices for the Holocene tectonic movements, (2) determination of distributions and block movements of the Quaternary marine terraces, (3) investigation of lithologic and geotechnical nature of study area, and (4) examination of the Cenozoic volcanic activities and determination of age of the dike swarms. Using data obtained from above mentioned analyses along with data related to earthquakes and active faults, probabilistic approach was performed to determine various potential hazards which may result from the

  18. Probabilistic finite elements for fracture and fatigue analysis

    Science.gov (United States)

    Liu, W. K.; Belytschko, T.; Lawrence, M.; Besterfield, G. H.

    1989-01-01

    The fusion of the probabilistic finite element method (PFEM) and reliability analysis for probabilistic fracture mechanics (PFM) is presented. A comprehensive method for determining the probability of fatigue failure for curved crack growth was developed. The criterion for failure or performance function is stated as: the fatigue life of a component must exceed the service life of the component; otherwise failure will occur. An enriched element that has the near-crack-tip singular strain field embedded in the element is used to formulate the equilibrium equation and solve for the stress intensity factors at the crack-tip. Performance and accuracy of the method is demonstrated on a classical mode 1 fatigue problem.

  19. Evaluation of piping fracture analysis method by benchmark study, 1

    International Nuclear Information System (INIS)

    Takahashi, Yukio; Kashima, Koichi; Kuwabara, Kazuo

    1987-01-01

    Importance of strength evaluation methods for cracked piping is growing with the progress of the rationalization of the nuclear piping system based on the leak-before-break concept. As an analytical tool, finite element method is principally used. To obtain the reliable solutions by the finite element programs, it is important to grasp the influences of various factors on the solutions. In this study, benchmark analysis is carried out for a stainless steel pipe with a circumferential through-wall crack subjected to four-point bending loading. Eight solutions obtained by using five finite element programs are compared with each other. Good agreement is obtained between the solutions on the deformation characteristics as well as fracture mechanics parameters. It is found through this study that the influence of the difference in the solution technique is generally small. (author)

  20. Failure analysis of the fractured wires in sternal perichronal loops.

    Science.gov (United States)

    Chao, Jesús; Voces, Roberto; Peña, Carmen

    2011-10-01

    We report failure analysis of sternal wires in two cases in which a perichronal fixation technique was used to close the sternotomy. Various characteristics of the retrieved wires were compared to those of unused wires of the same grade and same manufacturer and with surgical wire specifications. In both cases, wire fracture was un-branched and transgranular and proceeded by a high cycle fatigue process, apparently in the absence of corrosion. However, stress anlysis indicates that the effective stress produced during strong coughing is lower than the yield strength. Our findings suggest that in order to reduce the risk for sternal dehiscence, the diameter of the wire used should be increased. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Mezzo-scopic Analysis of Fracture Toughness in Steels

    Directory of Open Access Journals (Sweden)

    Miyata Takashi

    2002-01-01

    Full Text Available The cleavage fracture toughness of steels was mezzo-scopically analyzed on the basis of the statistical local fracture criterion approach. The statistical stress criterion at the crack tip region suggests that the cleavage fracture toughness in steels can be described as a function of the yield stress, the cleavage fracture stress, and other mechanical properties of the materials. Formulation of the cleavage fracture toughness was first examined through an investigation on correlation between the cleavage toughness and the cleavage fracture stress obtained in notched round bar specimens in accordance with the theoretical prediction. Then, the scatter of the toughness, specimen thickness effect on the toughness, deterioration of the toughness due to cold working and irradiation, and improvement of the toughness caused by the Ni addition, were analyzed through the formulation of the toughness.

  2. Disclosure of hydraulic fracturing fluid chemical additives: analysis of regulations.

    Science.gov (United States)

    Maule, Alexis L; Makey, Colleen M; Benson, Eugene B; Burrows, Isaac J; Scammell, Madeleine K

    2013-01-01

    Hydraulic fracturing is used to extract natural gas from shale formations. The process involves injecting into the ground fracturing fluids that contain thousands of gallons of chemical additives. Companies are not mandated by federal regulations to disclose the identities or quantities of chemicals used during hydraulic fracturing operations on private or public lands. States have begun to regulate hydraulic fracturing fluids by mandating chemical disclosure. These laws have shortcomings including nondisclosure of proprietary or "trade secret" mixtures, insufficient penalties for reporting inaccurate or incomplete information, and timelines that allow for after-the-fact reporting. These limitations leave lawmakers, regulators, public safety officers, and the public uninformed and ill-prepared to anticipate and respond to possible environmental and human health hazards associated with hydraulic fracturing fluids. We explore hydraulic fracturing exemptions from federal regulations, as well as current and future efforts to mandate chemical disclosure at the federal and state level.

  3. Prospective Computed Tomographic Analysis of Osteochondral Lesions of the Ankle Joint Associated With Ankle Fractures.

    Science.gov (United States)

    Nosewicz, Tomasz L; Beerekamp, M Suzan H; De Muinck Keizer, Robert-Jan O; Schepers, Tim; Maas, Mario; Niek van Dijk, C; Goslings, J Carel

    2016-08-01

    Osteochondral lesions (OCLs) associated with ankle fracture correlate with unfavorable outcome. The goals of this study were to detect OCLs following ankle fracture, to associate fracture type to OCLs and to investigate whether OCLs affect clinical outcome. 100 ankle fractures requiring operative treatment were prospectively included (46 men, 54 women; mean age 44 ± 14 years, range 20-77). All ankle fractures (conventional radiography; 71 Weber B, 22 Weber C, 1 Weber A, 4 isolated medial malleolus and 2 isolated posterior malleolus fractures) were treated by open reduction and internal fixation. Multidetector computed tomography (CT) was performed postoperatively. For each OCL, the location, size, and Loomer OCL classification (CT modified Berndt and Harty classification) were determined. The subjective Foot and Ankle Outcome Scoring (FAOS) was used for clinical outcome at 1 year. OCLs were found in 10/100 ankle fractures (10.0%). All OCLs were solitary talar lesions. Four OCLs were located posteromedial, 4 posterolateral, 1 anterolateral, and 1 anteromedial. There were 2 type I OCLs (subchondral compression), 6 type II OCLs (partial, nondisplaced fracture) and 2 type IV OCLs (displaced fracture). Mean OCL size (largest diameter) was 4.4 ± 1.7 mm (range, 1.7 mm to 6.2 mm). Chi-square analysis showed no significant association between ankle fracture type and occurrence of OCLs. OCLs did occur only in Lauge-Hansen stage III/IV ankle fractures. There were no significant differences in FAOS outcome between patients with or without OCLs. Ten percent of investigated ankle fractures had associated OCLs on CT. Although no significant association between fracture type and OCL was found, OCLs only occurred in Lauge-Hansen stage III/IV ankle fractures. With the numbers available, OCLs did not significantly affect clinical outcome at 1 year according to FAOS. Level IV, observational study. © The Author(s) 2016.

  4. Cardiovascular Risk Factor Analysis in Patients with a Recent Clinical Fracture at the Fracture Liaison Service

    Directory of Open Access Journals (Sweden)

    Caroline E. Wyers

    2014-01-01

    Full Text Available Patients with a low bone mineral density have an increased risk of cardiovascular diseases (CVD and venous thromboembolic events (VTE. The aim of our retrospective chart review was to investigate the prevalence of CVD, VTE, hypertension (HT, and diabetes mellitus type 2 (DM2 in patients with a recent clinical fracture visiting the Fracture Liaison Service (FLS. Out of 3057 patients aged 50–90 years, 1359 consecutive patients, who agreed and were able to visit the FLS for fracture risk evaluation, were included (71.7% women; mean age 65.2 yrs. Based on medical history, 29.9% had a history of CVD (13.7%, VTE (1.7%, HT (14.9%, and DM2 (7.1% or a combination. Their prevalence increased with age (21% in patients aged 50–59 years to 48% in patients aged >80 years and was higher in men than in women (36% versus 27%, but independent of bone mineral density and fracture type. Careful evaluation of medical history with respect to these risk factors should be performed in patients with a recent clinical fracture before starting treatment with medications that increase the risk of VTE or cardiovascular events, such as raloxifene, strontium ranelate, or NSAIDs.

  5. Analysis of the kinetics of the fragile fracture process in Mo monocrystals in quasi-relaxation

    International Nuclear Information System (INIS)

    Tamayo Meza, Pedro; Bautista Godinez, Eric Gustavo; Yermishkin, Viacheslav

    2008-01-01

    The method of quasi-relaxation, generally known as the force relaxation method, has been widely applied in the study of elementary dislocational processes. It is essential for the study and analysis of thermoactivated mechanisms, for the determination of the energy of interaction between dislocations and inclusions, in the definition of the dislocational constants, to predict the development of creep, and even for the study of fracture kinetics. For the first time the use of the quasi-relaxation method for evaluating the fragile fracture tendency was presented in the work. However, as usually carried out, the use of mass specimens and the development of a considerable plastic deformation in the vertex of the crack-notch sample limits the possibilities for this method. Many studies analyze the theoretical aspects of the fracture process, and the obtention of reliable quantitative information about the behavior of the dislocation based on an analytical description of the process, and how and when it influences the conditions under which the final catastrophic fracture occurs. This work proposes a new method to analyze the effect of a tension concentrator on the surface of Mo monocrystal specimens. The relaxation of the force and the increase in the crack opening is related to the development of the plastic zone in its vertex with the help of the Irwin correction. During the relaxation, the crack-groove grows until it attains the length of the plastic zone. Specimens with and without force concentrators were tested in quasi-relaxation. The cracks appearing under these conditions are analyzed using a scanning electron microscopy (SEM). The crack appearing in the specimens under load conditions, whose development produced heavy force relaxation, allowed the force relaxation value to be defined and compared in the specimens with and without tension concentrators (au)

  6. Medical Cost Analysis of the Osteoporotic Hip Fractures

    Directory of Open Access Journals (Sweden)

    Savaş Çamur

    2015-12-01

    Full Text Available Objective: Osteoporotic hip fractures decrease the life expectancy for 20% about 20-50% of the patients become permanently dependent in terms of walking for the rest of their life. Life expectancy is increasing in Turkey in the last 20 years. We investigated the impact of osteoporotic hip fractures which increase the morbidity and mortality on the national economy. Materials and Methods: A total of 81 patients admitted to our emergency department with the diagnosis of femur intertrochanteric fracture and femoral neck fracture between 2008 and 2012 were included in this study. We retrospectively evaluated the medical records and the medical costs of these patients from hospital information management system. Results: Of the 81 patients 32 (39.6% males and 49 (60.4% females meeting the inclusion criteria were included in this study. The mean age was 80.1 years (range, 61-103. Twenty-three (27.5% patients had femoral neck fracture and 58 (72.5% patients had intertrochanteric femur fracture. The mean length of hospital stay was 13.4 days in intertrochanteric femur fracture and 15.5 days in femoral neck fracture; average of the total days of hospitalization of all patients was 13.9 days. The average treatment cost per patient was 5,912.36 TL for intertrochanteric fractures, 5,753.00 TL for neck fractures, and 5,863.09 TL for the whole patient population. Conclusion: Hip fracture is a substantial cause of morbidity and mortality in elderly. Taking preventive measures before the fracture occurs may help to prevent this problem which has a high cost treatment and which is a substantial burden for the national economy.

  7. Analysis of nature of brazed joints fracture under operating conditions

    International Nuclear Information System (INIS)

    Orlov, A.V.; Gura, P.M.

    1985-01-01

    Technique establishing causes leading to brazed joint fracture in pressure boundary components, operating under heavy conditions of high temperature and corrosive medium is described. Some cases of tube brazed joint fractures in a superheater of 12Kh1MF and 08Kh18N10T steels are considered. The attention is paid on using metallography for determination of mechanical or corrosion fracture properties. The diagram is developed permitting to take into account the interrelation between the fracture area in the given zone and its strength

  8. Elastic-plastic fracture analysis of carbon steel piping using the latest CEGB R6 approach

    International Nuclear Information System (INIS)

    Kanno, S.; Hasegawa, K.; Shimizu, T.; Kobayashi, H.

    1991-01-01

    The elastic-plastic fracture of carbon steel piping having various pipe diameters and circumferential crack angles and subjected to a bending moment is analyzed using the latest United Kingdom Central Electricity Generating Board R6 approach. The elastic-plastic fracture criterion must be applied instead of the plastic collapse criterion with increase of the pipe diameter and the crack angle. A simplified elastic-plastic fracture analysis procedure based on the R6 approach is proposed. (author)

  9. comparison of elastic-plastic FE method and engineering method for RPV fracture mechanics analysis

    International Nuclear Information System (INIS)

    Sun Yingxue; Zheng Bin; Zhang Fenggang

    2009-01-01

    This paper described the FE analysis of elastic-plastic fracture mechanics for a crack in RPV belt line using ABAQUS code. It calculated and evaluated the stress intensity factor and J integral of crack under PTS transients. The result is also compared with that by engineering analysis method. It shows that the results using engineering analysis method is a little larger than the results using FE analysis of 3D elastic-plastic fracture mechanics, thus the engineering analysis method is conservative than the elastic-plastic fracture mechanics method. (authors)

  10. Elastic Plastic Fracture Analysis of an Aluminum COPV Liner

    Science.gov (United States)

    Forth, Scott; Gregg, Bradley; Bailey, Nathaniel

    2012-01-01

    Onboard any space-launch vehicle, composite over-wrapped pressure vessels (COPVs) may be utilized by propulsion or environmental control systems. The failure of a COPV has the potential to be catastrophic, resulting in the loss of vehicle, crew or mission. The latest COPV designs have reduced the wall-thickness of the metallic liner to the point where the material strains plastically during operation. At this time, the only method to determine the damage tolerance lifetime (safe-life) of a plastically responding metallic liner is through full-scale COPV testing. Conducting tests costs substantially more and can be far more time consuming than performing an analysis. As a result of this cost, there is a need to establish a qualifying process through the use of a crack growth analysis tool. This paper will discuss fracture analyses of plastically responding metallic liners in COPVs. Uni-axial strain tests have been completed on laboratory specimens to collect elastic-plastic crack growth data. This data has been modeled with the crack growth analysis tool, NASGRO 6.20 to predict the response of laboratory specimens and subsequently the complexity of a COPV.

  11. Fracture analysis of concrete gravity dam under earthquake induced ...

    African Journals Online (AJOL)

    In this paper, seismic fracture behavior of the concrete gravity dam using finite element (2D) theory has been studied. Bazant model which is non-linear fracture mechanics criteria as a measure of growth and smeared crack was chosen to develop profiles of the crack. Behavior of stress - strain curves of concrete as a ...

  12. Finite element analysis of intramedullary nailing and double locking plate for treating extra-articular proximal tibial fractures.

    Science.gov (United States)

    Chen, Fancheng; Huang, Xiaowei; Ya, Yingsun; Ma, Fenfen; Qian, Zhi; Shi, Jifei; Guo, Shuolei; Yu, Baoqing

    2018-01-16

    Proximal tibia fractures are one of the most familiar fractures. Surgical approaches are usually needed for anatomical reduction. However, no single treatment method has been widely established as the standard care. Our present study aims to compare the stress and stability of intramedullary nails (IMN) fixation and double locking plate (DLP) fixation in the treatment of extra-articular proximal tibial fractures. A three-dimensional (3D) finite element model of the extra-articular proximal tibial fracture, whose 2-cm bone gap began 7 cm from the tibial plateau articular surface, was created fixed by different fixation implants. The axial compressive load on an adult knee during single-limb stance was imitated by an axial force of 2500 N with a distribution of 60% to the medial compartment, while the distal end was fixed effectively. The equivalent von Mises stress and displacement of the model was used as the output measures for analysis. The maximal equivalent von Mises stress value of the system in the IMN model was 293.23 MPa, which was higher comparing against that in the DLP fixation model (147.04 MPa). And the mean stress of the model in the IMN model (9.25 MPa) was higher than that of the DLP fixation system in terms of equivalent von Mises stress (EVMS) (P tibial fractures of young patients.

  13. Morphological Changes Of The Root Surface And Fracture Resistance After Treatment Of Root Fracture By CO2 Laser And Glass Ionomer Or Mineral Trioxide Aggregates

    Science.gov (United States)

    Badr, Y. A.; Abd El-Gawad, L. M.; Ghaith, M. E.

    2009-09-01

    This in vitro study evaluates the morphological changes of the root surface and fracture resistance after treatment of root cracks by CO2 laser and glass Ionomer or mineral trioxide aggregates (MTA). Fifty freshly extracted human maxillary central incisor teeth with similar dimension were selected. Crowns were sectioned at the cemento-enamel junction, and the lengths of the roots were adjusted to 13 mm. A longitudinal groove with a dimension of 1×5 mm2 and a depth of 1.5 mm was prepared by a high speed fissure bur on the labial surface of the root. The roots were divided into 5 groups: the 10 root grooves in group 1 were remained unfilled and were used as a control group. The 10 root grooves in group 2 were filled with glass Ionomer, 10 root grooves in group 3 were filled with MTA, the 10 root grooves in group 4 were filled with glass Ionomer and irradiated by CO2 laser and the 10 root grooves in group 5 were filled with MTA and irradiated with CO2 laser. Scanning electron microscopy was performed for two samples in each group. Tests for fracture strength were performed using a universal testing machine and a round tip of a diameter of 4 mm. The force was applied vertically with a constant speed of 1 mm min 1. For each root, the force at the time of fracture was recorded in Newtons. Results were evaluated statistically with ANOVA and Turkey's Honestly Significant Difference (HSD) tests. SEM micrographs revealed that the melted masses and the plate-like crystals formed a tight Chemical bond between the cementum and glass Ionomer and melted masses and globular like structure between cementum and MTA. The mean fracture resistance was the maximum fracture resistance in group 5 (810.8 N). Glass Ionomer and MTA with the help of CO2 laser can be an alternative to the treatment of tooth crack or fracture. CO2 laser increase the resistance of the teeth to fracture.

  14. The Auger-spectroscopic study of the elemental composition of the fracture surface of titanic alloy vt-22 with different structure

    International Nuclear Information System (INIS)

    Tkachenko, E.A.; Chokin, K.Sh.; Masyagin, V.E.; Chasnikov, A.I.

    2002-01-01

    High titanium alloys belong to a group of materials with high thermal stability and strength-to-weight ratio, which, for example, are widely used in aviation. The structure and properties of this materials strongly depends on variations of their elemental composition. In the dependence on the content of alloying elements the structure after the hardening from β-phase changes that, in its turn, leads to the alteration of the mechanical properties. So, the study of the redistribution of the impurity and alloying elements at straining the alloys with different structures that associated with premature destruction of construction components made of the titanic alloys is of great interest. The present work performs the results of the Auger spectroscopic investigation of the elemental composition of the alloy VT-22 fraction surface. This investigation was fulfilled for the alloy samples with different structure: laminated (L), globular (G), and laminated-globular ones with the plasticity level 1280-1350 MPa. The alterations of the elemental concentrations on the fracture surface have been estimated with the special Auger-spectrometer (OSIPR-1). The analysis of the fracture surface for samples with L- and G-structures right after the destruction at different velocities have shown the enrichment of the surface with aluminium, oxygen, and carbon in bound state as titan carbide (TiC). At this, the content of these elements decreases with the growth of the test velocity. The impurities in the samples with different structures behave as follows. In the sample with L-structure sulphur, phosphorus, and calcium on the fracture surface have been detected. At this, with the growth of the test velocity their concentration increases, but not significantly. In the samples with G-structure sulphur presents on the surface only at great straining velocities, and phosphorus is absent. At the analysis of the obtained results, one should note that the fracture surface is being enriched

  15. Outcome analysis of sports-related multiple facial fractures.

    Science.gov (United States)

    Hwang, Kun; You, Sun Hye; Lee, Hong Sik

    2009-05-01

    In this paper, we report a retrospective study of 236 patients with facial bone fractures from various sports who were treated at the Department of Plastic and Reconstructive Surgery, Inha University Hospital, Incheon, South Korea, between February 1996 and April 2007. The medical records of these patients were reviewed and analyzed to determine the clinical characteristics and treatment of the sports-related facial bone fractures. The highest frequency of sports-related facial bone fractures was in the age group 11 to 20 years (40.3%); there was a significant male predominance in all age groups (13.75:1). The most common causes of the injury were soccer (38.1%), baseball (16.1%), basketball (12.7%), martial arts (6.4%), and skiing or snowboarding (11%). Fractures of the nasal bone were the most common in all sports; mandible fractures were common in soccer and martial arts, orbital bone fractures were common in baseball, basketball, and ice sports, and fractures of the zygoma were frequently seen in soccer and martial arts. The main causes of the sports injuries were direct body contact (50.8%), and the most commonly associated soft tissue injuries were found in the head and neck regions (92.3%). Nasal bone fractures were the most common (54.2%), and tripod fractures were the most common type of complex injuries (4.2%). The complication rate was 3.0%. Long-term epidemiological data regarding the natural history of sports-related facial bone fractures are important for the evaluation of existing preventative measures and for the development of new methods of injury prevention and treatment.

  16. Probabilistic fracture mechanics analysis of reactor vessel for pressurized thermal shock: the effect of residual stress and fracture toughness

    International Nuclear Information System (INIS)

    Jung, Sung Gyu; Jin, Tae Eun; Jhung, Myung Jo; Choi, Young Hwan

    2003-01-01

    The structural integrity of the reactor vessel with the approaching end of life must be assured for pressurized thermal shock. The regulation specifies the screening criteria for this and requires that specific analysis be performed for the reactor vessel which is anticipated to exceed the screening criteria at the end of plant life. In case the screening criteria is exceeded by the deterministic analysis, probabilistic analysis must be performed to show that failure probability is within the limit. In this study, probabilistic fracture mechanics analysis of the reactor vessel for pressurized thermal shock is performed and the effects of residual stress and master curve on the failure probability are investigated

  17. Development of autoradiographic method for measuring sorption of radionuclides on natural fracture surfaces

    International Nuclear Information System (INIS)

    Muuronen, S.

    1983-11-01

    On the basis of positive results about sorption of radionuclides in rock thin sections an autoradiographic method applicable for measurement sorption of radionuclides on rough rock surfaces was developed. There is no method available because 1) a plane film cannot be used because due to the roughness of rock surfaces 2) rock samples used in this investigation cannot be studied with microscopes and 3) autoradiogram cannot be studied fixed on the surface of a rock sample because the colours of the minerals in the sample will interfere with the interpretation. This report discusses experimental work done to find an useful proedure. In the development of the method main emphasis was put on investigation of the following steps: 1) preparation of the sample for equilibration and spiking; 2) properties of the covering paint for the rock surface and 3) testing of autoradiographic methods using different nuclear emulsions. As the result of these experiments promising autoradiograms with gel emulsion for sawed rock surfaces and with stripping film for rough rock surfaces were obtained. The mineralogic disribution of sorbed activity is easily seen in autoradiograms. Much work must still be done to get reliable quantitative information from autoradiograms. For developing of the autoradiographic method sawed plane rock samples of quartz feldspar intergrowth, pegmatite and limestone were used. In addition core samples of tonalite and mica gneiss from Olkiluoto were utilized. The distribution coefficients (Ksub(a)) obtained for cesium were 560 x 10 -4 and 620 x 10 -4 m 3 /m 2 for tonalite and mica gneiss, respectively. The results are little higher but of the same order of magnitude as obtained by the autoradiographic method using rock thin sections and by the batch method using crused samples. The natural fracture surface sorption study is a logical step in determining the scaling factor from laboratory to field studies. Field data will be needed to determine whether laboratory

  18. RIMAPS characterization of a surface in the variable aperture fracture model and determination of the main paths for water flow

    International Nuclear Information System (INIS)

    Fuentes, Nestor O.

    2003-01-01

    To understand the real incidence of fracture geometry in the unsteady behavior of flowing water channels, the RIMAPS (Rotated Image with Maximum Average Power Spectrum) technique is used to determine the main directions of these channels. This new characterization technique works on digitized images obtained from the surfaces under study. The present work presents the results of a comparison between the flow directions predicted by RIMAPS and the real channels directions observed in a laboratory experiment. A perfect accordance was verified between the directions obtained in both cases. It can be concluded from these results that geometrical characteristics of a fracture surface determine the main path directions for water flow. (author)

  19. Analysis of the pressure response of high angle multiple (HAM) fractures intersecting a welbore; Kokeisha multi fracture (HAM) kosei ni okeru atsuryoku oto kaiseki ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Ujo, S; Osato, K [Geothermal Energy Research and Development Co. Ltd., Tokyo (Japan); Arihara, N [Waseda University, Tokyo (Japan); Schroeder, R

    1996-05-01

    This paper reports pressure response analysis on wells piercing a high angle multi (HAM) fracture model. In this model which is defined on a three-dimensional space, a plurality of slanted fractures intersect with wells at high angles (however, intersection of fractures with each other is not considered). With respect to the pressure response analysis method using this model, the paper presents a basic differential equation on pressure drawdown and boundary conditions in the wells taking flows in the fractures pseudo-linear, as well as external boundary conditions in calculation regions (a reservoir spreads to an infinite distance, and its top and bottom are closed by non-water permeating beds). The paper also indicates that results of calculating a single vertical fracture model and a slanted fracture model by using a numerical computation program (MULFRAC) based on the above equations agree well respectively with the existing calculation results (calculations performed by Erlougher and Cinco et al). 5 refs., 6 figs.

  20. Analysis of the fractures of metallic materials using optical coherence tomography

    Science.gov (United States)

    Hutiu, Gh.; Duma, V.-F.; Demian, D.; Bradu, A.; Podoleanu, A. Gh.

    2017-06-01

    Forensic in situ investigations, for example for aviation, maritime, road, or rail accidents would benefit from a method that may allow to distinguish ductile from brittle fractures of metals - as material defects are one of the potential causes of such accidents. Currently, the gold standard in material studies is represented by scanning electron microscopy (SEM). However, SEM are large, lab-based systems, therefore in situ measurements are excluded. In addition, they are expensive and time-consuming. We have approached this problem and propose the use of Optical Coherence Tomography (OCT) in such investigations in order to overcome these disadvantages of SEM. In this respect, we demonstrate the capability to perform such fracture analysis by obtaining the topography of metallic surfaces using OCT. Different materials have been analyzed; in this presentation a sample of low soft carbon steel with the chemical composition of C 0.2%, Mn 1.15%, S 0.04%, P 0.05 % and Fe for the rest has been considered. An in-house developed Swept Source (SS) OCT system has been used, and height profiles have been generated for the sample surface. This profile allowed for concluding that the carbon steel sample was subjected to a ductile fracture. A validation of the OCT images obtained with a 10 microns resolution has been made with SEM images obtained with a 4 nm resolution. Although the OCT resolution is much lower than the one of SEM, we thus demonstrate that it is sufficient in order to obtain clear images of the grains of the metallic materials and thus to distinguish between ductile and brittle fractures. This study analysis opens avenues for a range of applications, including: (i) to determine the causes that have generated pipe ruptures, or structural failures of metallic bridges and buildings, as well as damages of machinery parts; (ii) to optimize the design of various machinery; (iii) to obtain data regarding the structure of metallic alloys); (iv) to improve the

  1. Cleaving the Halqeh-ye-nur diamonds: a dynamic fracture analysis.

    Science.gov (United States)

    Atkinson, Colin; Martineau, Philip M; Khan, Rizwan U A; Field, John E; Fisher, David; Davies, Nick M; Samartseva, Julia V; Putterman, Seth J; Hird, Jonathan R

    2015-03-28

    The degree of surface roughness and clarity with which a surface in a brittle material can be formed via fracture is known to be related to the speed of the propagating crack. Cracks traversing a brittle material at low speed produce very smooth surfaces, while those propagating faster create less reflective and rough surfaces (Buehler MJ, Gao H. 2006 Nature 439, 307-310 (doi:10.1038/nature04408)). The elastic wave speeds (c(l)≈18 000 m s(-1), c(s)≈11 750 m s(-1)) in diamond are fast (Willmott GR, Field JE. 2006 Phil. Mag. 86, 4305-4318 (doi:10.1080/14786430500482336)) and present a particular problem in creating smooth surfaces during the cleaving of diamond-a routine operation in the fashioning of diamonds for gemstone purposes--as the waves are reflected from the boundaries of the material and can add a tensile component to the propagating crack tip causing the well-known cleavage steps observed on diamond surfaces (Field JE. 1971 Contemp. Phys. 12, 1-31 (doi:10.1080/00107517108205103); Field JE. 1979 Properties of diamond, 1st edn, Academic Press; Wilks EM. 1958 Phil. Mag. 3, 1074-1080 (doi:10.1080/14786435808237036)). Here we report an analysis of two diamonds, having large dimensions and high aspect ratio, which from a gemological analysis are shown to have been cleaved from the same 200 carat specimen. A methodology for their manufacture is calculated by an analysis of a model problem. This takes into account the effect of multiple reflections from the sample boundaries. It is suggested that the lapidary had an intuitive guide to how to apply the cleavage force in order to control the crack speed. In particular, it is shown that it is likely that this technique caused the fracture to propagate at a lower speed. The sacrifice of a large diamond with the intention of creating thin plates, rather than a faceted gemstone, demonstrates how symbolism and beliefs associated with gemstones have changed over the centuries (Harlow GE. 1998 The nature

  2. [Analysis of 163 rib fractures by imaging examination].

    Science.gov (United States)

    Song, Tian-fu; Wang, Chao-chao

    2014-12-01

    To explore the applications of imaging examination on rib fracture sites in forensic identification. Features including the sites, numbers of the processed imaging examination and the first radiological technology at diagnosis in 56 cases of rib fractures from 163 injuries were retrospectively analyzed. The detection rate of the rib fractures within 14 days was 65.6%. The initial detection rate of anterior rib fracture proceeded by X-ray was 76.2%, then 90.5% detected at a second time X-ray, while the detection rate of CT was 66.7% and 80.0%, respectively. The initial detec- tion rate of rib fracture in axillary section proceeded by X-ray was 27.6%, then 58.6% detected at a second time X-ray, while the detection rate of CT was 54.3% and 80.4%, respectively. The initial detection rate of posterior rib fracture proceeded by X-ray was 63.6%, then 81.8% detected at a second time X-ray, while the detection rate of CT was 50.0% and 70.0%, respectively. It is important to pay attention to the use of combined imaging examinations and the follow-up results. In the cases of suspicious for rib fracture in axillary section, CT examination is suggested in such false X-ray negative cases.

  3. An analysis of 214 cases of rib fractures

    Directory of Open Access Journals (Sweden)

    Sule Karadayi

    2011-01-01

    Full Text Available INTRODUCTION: Rib fractures are the most common type of injury associated with trauma to the thorax. In this study, we investigated whether morbidity and mortality rates increased in correlation with the number of fractured ribs. MATERIALS AND METHODS: Data from 214 patients with rib fractures who applied or were referred to our clinic between January 2007 and December 2008 were retrospectively evaluated. The patients were allocated into three groups according to the number of fractures: 1 patients with an isolated rib fracture (RF1 (n = 50, 23.4%, 2 patients with two rib fractures (RF2 (n = 53, 24.8%, and 3 patients with more than two rib fractures (RF3 (n = 111, 51.9%. The patients were evaluated and compared according to the number of rib fractures, mean age, associated chest injuries (hemothorax, pneumothorax, and/or pulmonary contusion, and co-existing injuries to other systems. FINDINGS: The mean age of the patients was 51.5 years. The distribution of associated chest injuries was 30% in group RF1, 24.6% in group RF2, and 75.6% in group RF3 (p<0.05. Co-existing injuries to other systems were 24% in group RF1, 23.2% in group RF2, and 52.6% in group RF3 (p<0.05. Two patients (4% in group RF1, 2 patients (3.8% in group RF2, and 5 patients (4.5% in group RF3 (total n = 9; 4.2% died. CONCLUSION: Patients with any number of rib fractures should be carefully screened for co-existing injuries in other body systems and hospitalized to receive proper treatment.

  4. Detection of Natural Fractures from Observed Surface Seismic Data Based on a Linear-Slip Model

    Science.gov (United States)

    Chen, Huaizhen; Zhang, Guangzhi

    2018-03-01

    Natural fractures play an important role in migration of hydrocarbon fluids. Based on a rock physics effective model, the linear-slip model, which defines fracture parameters (fracture compliances) for quantitatively characterizing the effects of fractures on rock total compliance, we propose a method to detect natural fractures from observed seismic data via inversion for the fracture compliances. We first derive an approximate PP-wave reflection coefficient in terms of fracture compliances. Using the approximate reflection coefficient, we derive azimuthal elastic impedance as a function of fracture compliances. An inversion method to estimate fracture compliances from seismic data is presented based on a Bayesian framework and azimuthal elastic impedance, which is implemented in a two-step procedure: a least-squares inversion for azimuthal elastic impedance and an iterative inversion for fracture compliances. We apply the inversion method to synthetic and real data to verify its stability and reasonability. Synthetic tests confirm that the method can make a stable estimation of fracture compliances in the case of seismic data containing a moderate signal-to-noise ratio for Gaussian noise, and the test on real data reveals that reasonable fracture compliances are obtained using the proposed method.

  5. Fracture analysis of the planet support used in a nuclear power plant

    Directory of Open Access Journals (Sweden)

    Zu Shuai

    2016-01-01

    Full Text Available In this paper, the fracture analysis of the planet support, which was made of aluminium alloy and used in an electric actuator, was investigated. The laboratory analysis was conducted to find out whether there are defects generated during manufacturing process. Besides, the finite element analysis was carried out to calculate the maximum tensile stress and compared it with the material strength. The mechanism of the fracture was found to be low-cycle fatigue.

  6. ROCK FRACTURES NEAR FAULTS: SPECIFIC FEATURES OF STRUCTURAL‐PARAGENETIC ANALYSIS

    Directory of Open Access Journals (Sweden)

    Yu. P. Burzunova

    2017-01-01

    Full Text Available The new approach to structural‐paragenetic analysis of near‐fault fractures [Seminsky, 2014, 2015] and specific features of its application are discussed. This approach was tested in studies of fracturing in West Pribaikalie and Central Mongolia. We give some recommendations concerning collection, selection and initial processing of the data on fractures and faults. The analysis technique is briefly described, and its distinctive details are specified. Under the new approach, we compare systems of natural fractures with the standard joint sets. By analysing the mass measurements of the orientations of joint sets in a fault zone, it becomes possible to reveal the characteristics of this fault zone, such as its structure, morphogenetic type, etc. The comparative analysis is based on the identification of the main fracture paragenesis near the faults. This paragenesis is represented by a triplet of mutually perpendicular joint sets. The technique uses the qualitative approach to establish the rank hierarchy of fractures and stress fields on the basis of genetic subordination. We collect and analyse the data on tectonic fractures identified from a number of indicators, the main of which are the geometric structure of the (systematic or chaotic fracture system, and shear type of fractures. The new technique can be applied to analyse other genetic types of fractures (primary, hypergenic, provided that tectonic stresses were significantly involved in fracturing, which is evidenced by the corresponding indicators. Methods for conducting geological and structural observations are uniform for all sites and points, and increasing the number of observation points provides for a more effective use of the new technique. In our paper, we give specific parameters for constructing circle fracture diagrams. All the maximums in the diagram are involved in the analysis for comparison with the standard patterns. Errors caused by random coincidence are minimized

  7. In-situ bending under tension shear fracture analysis and microstructure “earthquake” of DP780 dual phase steels

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yixi, E-mail: yxzhao@sjtu.edu.cn [State Key Laboratory of Mechanical System and Vibration, Shanghai Key Laboratory of Digital Manufacture for Thin-walled Structures, Shanghai Jiao Tong University, Shanghai 200240 (China); Huang, Sheng [State Key Laboratory of Mechanical System and Vibration, Shanghai Key Laboratory of Digital Manufacture for Thin-walled Structures, Shanghai Jiao Tong University, Shanghai 200240 (China); Dan, Wenjiao; Zhang, Weigang [Innovation Center for Advanced Ship and Deep-Sea Exploration, Department of Engineering Mechanics, Shanghai Jiao Tong University, Shanghai 200240 (China); Li, Shuhui [State Key Laboratory of Mechanical System and Vibration, Shanghai Key Laboratory of Digital Manufacture for Thin-walled Structures, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2017-05-17

    Dual phase (DP) steels consist of hard brittle martensite phase and soft ductile ferrite phase. With a novel bending under tension test system, in-situ symmetrical bending under tension experiments were carried out and photomicrographs of bending surface were recorded. The microstructure “earthquake” of DP780 dual phase steels was observed in the bending under tension process. By analyzing the in-situ images serious, the initiation, coalescence of cavities and propagation of micro-cracks until final fracture were analyzed. The micro-cracks form only in the outside surface of bending radius, and mainly appear near the phase boundary of ferrite and martensite. Micro-cracks coalesce and propagate in the direction perpendicular to the stretching direction approximately, and at the phase boundary of martensite and ferrite. Furthermore, digital image correlation technology was used in this study to analysis the strain distribution between ferrite and martensite during the bending under tension deformation and fracture.

  8. Epidemiological analysis of mandibular fractures treated in Sao Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    Kelly Marinho

    2015-10-01

    Conclusion: The treatment of mandibular fractures should be aimed at restoring the occlusion and mastication function, with surgery being the most indicated treatment, using reduction and internal fixation with the use of a plates and screws system based on the experience of the authors. Knowledge of surgical techniques and methods of reduction and fixation of fractures, and periodic monitoring allow these patients to receive the appropriate treatment.

  9. New quantitative ultrasound techniques for bone analysis at the distal radius in hip fracture cases: differences between femoral neck and trochanteric fractures.

    Science.gov (United States)

    Horii, Motoyuki; Fujiwara, Hiroyoshi; Sakai, Ryo; Sawada, Koshiro; Mikami, Yasuo; Toyama, Syogo; Ozaki, Etsuko; Kuriyama, Nagato; Kurokawa, Masao; Kubo, Toshikazu

    2017-01-01

    Ample evidence on etiological and pathological differences between femoral neck and trochanteric fracture cases suggests the possibility of individualized treatment. There are many issues related to areal bone mineral density and other quantitative computed tomography parameters of the proximal femur. Although osteoporosis is a systemic problem, little has been reported regarding differences in bone structural parameters, including bone mineral density, between them in regions other than the proximal femur. Participants were consecutive female patients >50 years of age admitted to the Saiseikai Suita Hospital (Osaka prefecture, Japan) for their first hip fracture between January 2012 and September 2014. Cortical thickness (CoTh, mm), volumetric trabecular bone mineral density (TBD, mg/cm 3 ), and elastic modulus of trabecular bone (EMTb, GPa) were obtained as the new QUS parameters using the LD-100 system (Oyo Electric, Kyoto, Japan). The mean values of these parameters were compared between femoral neck and trochanteric fracture cases. In addition, correlations between age and each QUS parameter were investigated for each fracture type. A receiver operating characteristic (ROC) curve analysis was performed to examine the degree of effect each parameter on the fracture types. The area under the curve (AUC) for each parameter was compared to the AUC for age. There were 63 cases of femoral neck fracture (mean age, 78.2 years) and 37 cases of trochanteric fracture (mean age, 85.9 years). Mean TBD and EMTb were significantly higher for femoral neck fractures. There were significant negative correlations between QUS parameters and age for femoral neck fractures (P fractures were above those for trochanteric fractures for TBD and EMTb. AUCs were 0.72 for age, and 0.61, 0.65, and 0.65 for CoTh, TBD, and EMTb, respectively. The new QUS parameters indicated that TR fracture cases were more osteoporotic than were FN fracture cases, even at the distal radius. There might be

  10. Determining when a fracture occurred: Does the method matter? Analysis of the similarity of three different methods for estimating time since fracture of juvenile long bones.

    Science.gov (United States)

    Drury, Anne; Cunningham, Craig

    2018-01-01

    Radiographic fracture date estimation is a critical component of skeletal trauma analysis in the living. Several timetables have been proposed for how the appearance of radiographic features can be interpreted to provide a likely time frame for fracture occurrence. This study compares three such timetables for pediatric fractures, by Islam et al. (2000), Malone et al. (2011), and Prosser et al. (2012), in order to determine whether the fracture date ranges produced by using these methods are in agreement with one another. Fracture date ranges were estimated for 112 long bone fractures in 96 children aged 1-17 years, using the three different timetables. The extent of similarity of the intervals was tested by statistically comparing the overlap between the ranges. Results showed that none of the methods were in perfect agreement with one another. Differences seen included the size of the estimated date range for when a fracture occurred, and the specific dates given for both the upper and lower ends of the fracture date range. There was greater similarity between the ranges produced by Malone et al. (2011) and both the other two studies than there was between Islam et al. (2000) and Prosser et al. (2012). The greatest similarity existed between Malone et al. (2011) and Islam et al. (2000). The extent of differences between methods can vary widely, depending on the fracture analysed. Using one timetable gives an average earliest possible fracture date of less than 2 days before another, but the range was extreme, with one method estimating minimum time since fracture as 25 days before another method for a given fracture. In most cases, one method gave maximum time since fracture as a week less than the other two methods, but range was extreme and some estimates were nearly two months different. The variability in fracture date estimates given by these timetables indicates that caution should be exercised when estimating the timing of a juvenile fracture if relying

  11. Adherence to a Mediterranean-style diet and incident fractures: pooled analysis of observational evidence.

    Science.gov (United States)

    Kunutsor, Setor K; Laukkanen, Jari A; Whitehouse, Michael R; Blom, Ashley W

    2018-06-01

    The Mediterranean diet is associated with decreased morbidity and mortality from various chronic diseases. Adherence to a Mediterranean-style diet has been suggested to have protective effects on bone health and decreases the incidence of bone fractures, but the evidence is not clear. We conducted a systematic review and meta-analysis of available observational studies to quantify the association between adherence to a Mediterranean-style diet, as assessed by the Mediterranean Diet Score (MDS), and the risk of fractures in the general population. Relevant studies were identified in a literature search of MEDLINE, EMBASE, Web of Science, and reference lists of relevant studies to October 2016. Relative risks (RRS) with 95% confidence intervals (CIs) were aggregated using random-effects models. Five observational studies with data on 353,076 non-overlapping participants and 33,576 total fractures (including 6,881 hip fractures) were included. The pooled fully adjusted RR (95% CI) for hip fractures per 2-point increment in adherence to the MDS was 0.82 (0.71-0.96). Adherence to the MDS was not associated with the risk of any or total fractures based on pooled analysis of only two studies. Limited observational evidence supports a beneficial effect of adherence to a Mediterranean-style diet on the incidence of hip fractures. Well-designed intervention studies are needed to elucidate the relationship between adherence to a Mediterranean-style diet and the risk of adverse bone health outcomes such as fractures.

  12. Semi-Analysis for the Pseudo-Colloid Migration of Multi-member Decay Chains in the Fractured Porous Medium with the Flux Boundary

    International Nuclear Information System (INIS)

    Jeong, Mi Seon; Hwang, Yong Soo; Kang, Chul Hyung

    2010-01-01

    stationary solid wall surface of a fracture. Even though the colloid can not penetrate into the surrounding rock matrix, the solute diffuses into the porous matrix. In this analysis, the Laplace transformed solution is derived for a pseudo-colloid in a fracture and a solute in a fracture and a surrounding rock with a realistic inlet boundary condition. The canonical form solutions are used for the Fortran based a computational code which uses a special subroutine for the inversion of Laplace transform based on the Theory of Green. This new solution can be combined with the total system performance assessment code such as the Goldsim which can exchange the information such as the inlet concentration and the outlet flux with the newly developed code by using its dll file

  13. Analysis of impact energy to fracture un-notched charpy specimens made from railroad tank car steel

    Science.gov (United States)

    2007-09-11

    This paper describes a nonlinear finite element analysis : (FEA) framework that examines the impact energy to fracture : unnotched Charpy specimens by an oversized, nonstandard : pendulum impactor called the Bulk Fracture Charpy Machine : (BFCM). The...

  14. Lubrication theory analysis of the permeability of rough-walled fractures

    International Nuclear Information System (INIS)

    Zimmerman, R.W.; Kumar, S.; Bodvarsson, G.S.

    1991-01-01

    The flow of a fluid between the rough surfaces of a rock fracture is very complex, due to the tortuous paths followed by the fluid particles. Exact analytical modeling of these flows is made difficult by the irregular geometry of rock fracture surfaces, while full three-dimensional numerical simulations of these flows are as yet still impractical. To overcome the difficulties of working with the three-dimensional Navier-Stokes equations, the simpler Reynolds lubrication equation has sometimes been used to model flow in fractures. This paper focuses on two aspects of lubrication theory. First, lubrication theory is applied to two simplified aperture profiles, sinusoidal and sawtooth, and analytical expressions are found for the permeabilities. These results are then compared with numerical results obtained by solving the lubrication equation for fractures with random surfaces. Secondly, the validity of the lubrication equations for modeling flow in rough fractures is studied by examining higher-order perturbation solutions, as well as numerical solutions, to the Navier-Stokes equations for flow in fractures with sinusoidally-varying apertures. 22 refs., 6 figs

  15. Monitoring of surface deformation and microseismicity applied to radioactive waste disposal through hydraulic fracturing at Oak Ridge National Laboratory

    International Nuclear Information System (INIS)

    Stow, S.H.; Haase, C.S.; Switek, J.; Holzhausen, G.R.; Majer, E.

    1985-01-01

    Low-level liquid nuclear wastes are disposed of at Oak Ridge National Laboratory by the hydrofracture process. Wastes are mixed with cement and other additives to form a slurry that is injected into shale of low permeability at 300 m depth. The slurry spreads radially along bedding plane fractures before setting as a grout. Different methods for monitoring the location and behavior of the fractures have been investigated. Radioactive grout sheets can be located by gamma-ray logging of cased observation wells. Two other methods are based on the fact that the ground surface is deformed by the injection. The first entails surface leveling of a series of benchmarks; uplift up to 2.5 cm occurs. The second method involves use of tiltmeters that are sensitive and measure ground deformation in real time during an injection. Both methods show subsidence during the weeks following an injection. Interpretive models for the tiltmeter data are based on the elastic response of isotropic and anisotropic media to the inflation of a fluid-filled fracture. A fourth monitoring method is based on microseismicity. Geophone arrays were used to characterize the fracture process and to provide initial assessment of the feasibility of using seismic measurements to map the fractures as they form. An evaluation of each method is presented. 8 refs., 6 figs

  16. Monitoring of surface deformation and microseismicity applied to radioactive waste disposal through hydraulic fracturing at Oak Ridge National Laboratory

    International Nuclear Information System (INIS)

    Stow, S.H.; Haase, C.S.; Switek, J.; Holzhausen, G.R.; Majer, E.; Applied Geomechanics, Inc., Santa Cruz, CA; Lawrence Berkeley Lab., CA)

    1985-01-01

    Low-level liquid nuclear wastes are disposed of at Oak Ridge National Laboratory by the hydrofracture process. Wastes are mixed with cement and other additives to form a slurry that is injected into shale of low permeability at 300 m depth. The slurry spreads radially along bedding plane fractures before setting as a grout. Different methods for monitoring the location and behavior of the fractures have been investigated. Radioactive grout sheets can be located by gamma-ray logging of cased observation wells. Two other methods are based on the fact that the ground surface is deformed by the injection. The first entails surface leveling of a series of benchmarks; uplift up to 2.5 cm occurs. The second method involves use of tiltmeters that are sensitive and measure ground deformation in real time during an injection. Both methods show subsidence during the weeks following an injection. Interpretive models for the tiltmeter data are based on the elastic response of isotropic and anisotropic media to the inflation of a fluid-filled fracture. A fourth monitoring method is based on microseismicity. Geophone arrays were used to characterize the fracture process and to provide initial assessment of the feasibility of using seismic measurements to map the fractures as they form. An evaluation of each method is presented

  17. Fracture overprinting history using Markov chain analysis: Windsor-Kennetcook subbasin, Maritimes Basin, Canada

    Science.gov (United States)

    Snyder, Morgan E.; Waldron, John W. F.

    2018-03-01

    The deformation history of the Upper Paleozoic Maritimes Basin, Atlantic Canada, can be partially unraveled by examining fractures (joints, veins, and faults) that are well exposed on the shorelines of the macrotidal Bay of Fundy, in subsurface core, and on image logs. Data were collected from coastal outcrops and well core across the Windsor-Kennetcook subbasin, a subbasin in the Maritimes Basin, using the circular scan-line and vertical scan-line methods in outcrop, and FMI Image log analysis of core. We use cross-cutting and abutting relationships between fractures to understand relative timing of fracturing, followed by a statistical test (Markov chain analysis) to separate groups of fractures. This analysis, previously used in sedimentology, was modified to statistically test the randomness of fracture timing relationships. The results of the Markov chain analysis suggest that fracture initiation can be attributed to movement along the Minas Fault Zone, an E-W fault system that bounds the Windsor-Kennetcook subbasin to the north. Four sets of fractures are related to dextral strike slip along the Minas Fault Zone in the late Paleozoic, and four sets are related to sinistral reactivation of the same boundary in the Mesozoic.

  18. Diagnostic value of MR analysis of cartilaginous lesions compared with intraoperative arthroscopy in calcaneal fractures

    International Nuclear Information System (INIS)

    Schroeder, R.J.; Nekwasil, S.J.; Felix, R.; Hidajat, N.; Boack, D.H.; Haas, N.P.; Martus, P.

    2005-01-01

    Purpose: To determine the diagnostic value of MRI in preoperative analysis and classification of cartilaginous lesions - especially of the posterior facet - in traumatic calcaneal fractures compared with intraoperative arthroscopy. Materials and Methods: Twenty-four consecutive patients with traumatic calcaneal fractures underwent prospective MRI of the subtalar joint surface using T1- and T2-weighted spin echo sequences and fat suppressed 3D gradient echo sequences in semicoronal slice orientation (1.5 T MRI). After randomization, the images were analyzed by two blinded and independent readers experienced in MRI. The results were compared with the intraoperative arthroscopic findings as to location and depth of the defects using the Outerbridge classification. Results: We examined 12 calcaneal fractures of type 2, 8 of type 3 and 4 of type 4 according to the Sanders classification. With respect to principal detection and exact classification, 67 to 96 (69.8%) of all arthroscopic verified cartilaginous defects were diagnosed correctly by MRI. Disregarding the degree of the defects, 38 of 44 (86.4%) chondral lesions were detected (sensitivity: 86.4%, specificity: 86.5%, diagnostic accuracy: 86.5%). Considering the chondral lesions of degrees 3 and 4 together, the sensitivity was 86.0%, the specificity 86.8%, and the diagnostic accuracy 86.5%. Assessing these degrees separately, the sensitivity was only 33.3% for degree 3 and 58.1% for degree 4, whereas the specificity was definitely higher with 82.1% for degree 3 and 89.2% for degree 4. (orig.)

  19. Sensitivity Analysis of the Bone Fracture Risk Model

    Science.gov (United States)

    Lewandowski, Beth; Myers, Jerry; Sibonga, Jean Diane

    2017-01-01

    Introduction: The probability of bone fracture during and after spaceflight is quantified to aid in mission planning, to determine required astronaut fitness standards and training requirements and to inform countermeasure research and design. Probability is quantified with a probabilistic modeling approach where distributions of model parameter values, instead of single deterministic values, capture the parameter variability within the astronaut population and fracture predictions are probability distributions with a mean value and an associated uncertainty. Because of this uncertainty, the model in its current state cannot discern an effect of countermeasures on fracture probability, for example between use and non-use of bisphosphonates or between spaceflight exercise performed with the Advanced Resistive Exercise Device (ARED) or on devices prior to installation of ARED on the International Space Station. This is thought to be due to the inability to measure key contributors to bone strength, for example, geometry and volumetric distributions of bone mass, with areal bone mineral density (BMD) measurement techniques. To further the applicability of model, we performed a parameter sensitivity study aimed at identifying those parameter uncertainties that most effect the model forecasts in order to determine what areas of the model needed enhancements for reducing uncertainty. Methods: The bone fracture risk model (BFxRM), originally published in (Nelson et al) is a probabilistic model that can assess the risk of astronaut bone fracture. This is accomplished by utilizing biomechanical models to assess the applied loads; utilizing models of spaceflight BMD loss in at-risk skeletal locations; quantifying bone strength through a relationship between areal BMD and bone failure load; and relating fracture risk index (FRI), the ratio of applied load to bone strength, to fracture probability. There are many factors associated with these calculations including

  20. [ANALYSIS OF CLINICAL EFFECT IN SURGICAL TREATMENT OF Maisonneuve FRACTURE].

    Science.gov (United States)

    Zhang, Zhiwen; Cai, Xianhua; Wei, Shijun; Liu, Ximing

    2015-03-01

    To investigate the operative method and short-term effectiveness in the surgical treatment of Maisonneuve fracture. Between January 2010 and February 2013, 23 patients with Maisonneuve fracture were treated. There were 14 males and 9 females with an average age of 40.3 years (range, 30-68 years). The causes of injuries were falling injury in 11 patients, sports related injury in 5 patients, traffic accident injury in 4 patients, and falling injury from height in 3 patients. The interval between injury and operation was 7-10 days (mean, 8.5 days). All of fractures were closed. Three patients had combined injury of deltoid ligament. The surgical procedures included surgical reduction and fixation of medial malleolus fracture and posterior malleolus fracture, repair of the deltoid ligament with ground anchor suture, and fixation of the disrupted distal tibiofibular syndesmosis. All incisions achieved primary healing, no postoperative complications such as infection occurred. Twenty-one patients were followed up 24-36 months (mean, 26.5 months). No patients complained of pain, tenderness, and obvious swelling of the ankle. At 3-6 months (mean, 4.6 months) after operation, X-ray films showed bony union of fractures and normal mortises in 21 patients. And no traumatic arthritis was observed with reliable fixation. The range of motion of ankle dorsi flexion and plantar flexion was 30-40 degrees) (mean, 34.5 degrees) Baird-Jackson anide functional score was 85-100 (mean, 94); 16 cases were rated as excellent, 4 as good, and 1 as fair with an excellent and good rate of 95.2%. Surgical treatments of Maisonneuve fracture include surgical reduction and fixation of the medial malleolus and posterior malleolus, repair of the deltoid ligament and fixation of the disrupted distal tibiofibular syndesmosis, and good effectiveness can be achieved.

  1. Surface analysis and techniques in biology

    CERN Document Server

    Smentkowski, Vincent S

    2014-01-01

    This book highlights state-of-the-art surface analytical instrumentation, advanced data analysis tools, and the use of complimentary surface analytical instrumentation to perform a complete analysis of biological systems.

  2. Fracture Analysis of basement rock: A case example of the Eastern Part of the Peninsular Malaysia

    International Nuclear Information System (INIS)

    Shamsuddin, A; Ghosh, D

    2015-01-01

    In general, reservoir rocks can be defined into carbonates, tight elastics and basement rocks. Basement rocks came to be highlighted as their characteristics are quite complicated and remained as a significant challenge in exploration and production area. Motivation of this research is to solve the problem in some area in the Malay Basin which consist fractured basement reservoirs. Thus, in order to increase understanding about their characteristic, a study was conducted in the Eastern part of the Peninsular Malaysia. The study includes the main rock types that resemble the offshore rocks and analysis on the factors that give some effect on fracture characteristic that influence fracture systems and fracture networks. This study will allow better fracture prediction which will be beneficial for future hydrocarbon prediction in this region

  3. [Correlation analysis between residual displacement and hip function after reconstruction of acetabular fractures].

    Science.gov (United States)

    Ma, Kunlong; Fang, Yue; Luan, Fujun; Tu, Chongqi; Yang, Tianfu

    2012-03-01

    To investigate the relationships between residual displacement of weight-bearing and non weight-bearing zones (gap displacement and step displacement) and hip function by analyzing the CT images after reconstruction of acetabular fractures. The CT measures and clinical outcome were retrospectively analyzed from 48 patients with displaced acetabular fracture between June 2004 and June 2009. All patients were treated by open reduction and internal fixation, and were followed up 24 to 72 months (mean, 36 months); all fractures healed after operation. The residual displacement involved the weight-bearing zone in 30 cases (weight-bearing group), and involved the non weight-bearing zone in 18 cases (non weight-bearing group). The clinical outcomes were evaluated by Merle d'Aubigné-Postel criteria, and the reduction of articular surface by CT images, including the maximums of two indexes (gap displacement and step displacement). All the data were analyzed in accordance with the Spearman rank correlation coefficient analysis. There was strong negative correlation between the hip function and the residual displacement values in weight-bearing group (r(s) = -0.722, P = 0.001). But there was no correlation between the hip function and the residual displacement values in non weight-bearing group (r(s) = 0.481, P = 0.059). The results of clinical follow-up were similar to the correlation analysis results. In weight-bearing group, the hip function had strong negative correlation with step displacement (r(s) = 0.825, P = 0.002), but it had no correlation with gap displacement (r(s) = 0.577, P = 0.134). In patients with acetabular fracture, the hip function has correlation not only with the extent of the residual displacement but also with the location of the residual displacement, so the residual displacement of weight-bearing zone is a key factor to affect the hip function. In patients with residual displacement in weight-bearing zone, the bigger the step displacement is, the

  4. Dairy product consumption and risk of hip fracture: a systematic review and meta-analysis

    OpenAIRE

    Bian, Shanshan; Hu, Jingmin; Zhang, Kai; Wang, Yunguo; Yu, Miaohui; Ma, Jie

    2018-01-01

    Background Dairy product consumption may affect the risk of hip fracture, but previous studies have reported inconsistent findings. The primary aim of our meta-analysis was to examine and quantify the potential association of dairy product consumption with risk of hip fracture. Methods We searched the databases of PubMed and EMBASE for relevant articles from their inception through April 17, 2017. The final analysis included 10 cohort studies and 8 case-control studies. Random-effects models ...

  5. Fracture mechanical analysis of strengthened concrete tension members with one crack

    DEFF Research Database (Denmark)

    Hansen, Christian Skodborg; Stang, Henrik

    2012-01-01

    A concrete tension member strengthened 2 with fiber reinforced polymer plates on two sides 3 is analyzed with non-linear fracture mechanics. The 4 analysis of the strengthened tension member incorpo5 rates cohesive properties for both concrete and inter6 face between concrete and strengthening...... the structural classification parameters, is inves13 tigated in a non-dimensional analysis, and found to 14 depend strongly on the ratio between interfacial and 15 concrete fracture energies....

  6. Clinical Utility of Dual-Energy CT Analysis of Bone Marrow Edema in Acute Wrist Fractures.

    Science.gov (United States)

    Ali, Ismail T; Wong, William D; Liang, Teresa; Khosa, Faisal; Mian, Memoona; Jalal, Sabeena; Nicolaou, Savvas

    2018-04-01

    The purpose of this study is to determine the utility of dual-energy CT (DECT) for assessing carpal fractures and to obtain an attenuation value cutoff (in Hounsfield units) to identify bone marrow edema due to an acute carpal fracture. In this retrospective study, 24 patients who presented with wrist fractures from September 3, 2014, through March 9, 2015, underwent imaging with DECT (80 and 140 kVp). Using the three-material decomposition algorithm specific for virtual noncalcium to construct images, two radiologists identified carpal fractures and associated bone marrow edema. Readers noted the attenuation at areas with and without bone marrow edema. The cutoff value was obtained by ROC analysis and was internally validated on 13 separate patients with suspected wrist fractures. A p edema than in areas without it (p edema associated with acute wrist fractures with 100% sensitivity and 99.5% specificity, compared with visual DECT interpretation. In the 13 validation cases, the cutoff of 5.90 HU identified bone marrow edema with 100% accuracy, compared with visual interpretation. Kappa values were 0.83 between the two readings by reader 1, and 0.73 and 0.96 comparing the two readings of reader 1 with the reading by reader 2. DECT is a useful tool for identifying bone marrow edema in the setting of acute wrist fractures, providing an alternative to MRI. A cutoff value of 5.90 HU can be used for accurate diagnosis and exclusion of carpal fractures.

  7. Stress analysis of implant-bone fixation at different fracture angle

    Science.gov (United States)

    Izzawati, B.; Daud, R.; Afendi, M.; Majid, MS Abdul; Zain, N. A. M.; Bajuri, Y.

    2017-10-01

    Internal fixation is a mechanism purposed to maintain and protect the reduction of a fracture. Understanding of the fixation stability is necessary to determine parameters influence the mechanical stability and the risk of implant failure. A static structural analysis on a bone fracture fixation was developed to simulate and analyse the biomechanics of a diaphysis shaft fracture with a compression plate and conventional screws. This study aims to determine a critical area of the implant to be fractured based on different implant material and angle of fracture (i.e. 0°, 30° and 45°). Several factors were shown to influence stability to implant after surgical. The stainless steel, (S. S) and Titanium, (Ti) screws experienced the highest stress at 30° fracture angle. The fracture angle had a most significant effect on the conventional screw as compared to the compression plate. The stress was significantly higher in S.S material as compared to Ti material, with concentrated on the 4th screw for all range of fracture angle. It was also noted that the screws closest to the intense concentration stress areas on the compression plate experienced increasing amounts of stress. The highest was observed at the screw thread-head junction.

  8. Adaptive Finite Element-Discrete Element Analysis for Microseismic Modelling of Hydraulic Fracture Propagation of Perforation in Horizontal Well considering Pre-Existing Fractures

    Directory of Open Access Journals (Sweden)

    Yongliang Wang

    2018-01-01

    Full Text Available Hydrofracturing technology of perforated horizontal well has been widely used to stimulate the tight hydrocarbon reservoirs for gas production. To predict the hydraulic fracture propagation, the microseismicity can be used to infer hydraulic fractures state; by the effective numerical methods, microseismic events can be addressed from changes of the computed stresses. In numerical models, due to the challenges in accurately representing the complex structure of naturally fractured reservoir, the interaction between hydraulic and pre-existing fractures has not yet been considered and handled satisfactorily. To overcome these challenges, the adaptive finite element-discrete element method is used to refine mesh, effectively identify the fractures propagation, and investigate microseismic modelling. Numerical models are composed of hydraulic fractures, pre-existing fractures, and microscale pores, and the seepage analysis based on the Darcy’s law is used to determine fluid flow; then moment tensors in microseismicity are computed based on the computed stresses. Unfractured and naturally fractured models are compared to assess the influences of pre-existing fractures on hydrofracturing. The damaged and contact slip events were detected by the magnitudes, B-values, Hudson source type plots, and focal spheres.

  9. Cost-effectiveness analysis of treatments for vertebral compression fractures.

    Science.gov (United States)

    Edidin, Avram A; Ong, Kevin L; Lau, Edmund; Schmier, Jordana K; Kemner, Jason E; Kurtz, Steven M

    2012-07-01

    Vertebral compression fractures (VCFs) can be treated by nonsurgical management or by minimally invasive surgical treatment including vertebroplasty and balloon kyphoplasty. The purpose of the present study was to characterize the cost to Medicare for treating VCF-diagnosed patients by nonsurgical management, vertebroplasty, or kyphoplasty. We hypothesized that surgical treatments for VCFs using vertebroplasty or kyphoplasty would be a cost-effective alternative to nonsurgical management for the Medicare patient population. Cost per life-year gained for VCF patients in the US Medicare population was compared between operated (kyphoplasty and vertebroplasty) and non-operated patients and between kyphoplasty and vertebroplasty patients, all as a function of patient age and gender. Life expectancy was estimated using a parametric Weibull survival model (adjusted for comorbidities) for 858 978 VCF patients in the 100% Medicare dataset (2005-2008). Median payer costs were identified for each treatment group for up to 3 years following VCF diagnosis, based on 67 018 VCF patients in the 5% Medicare dataset (2005-2008). A discount rate of 3% was used for the base case in the cost-effectiveness analysis, with 0% and 5% discount rates used in sensitivity analyses. After accounting for the differences in median costs and using a discount rate of 3%, the cost per life-year gained for kyphoplasty and vertebroplasty patients ranged from $US1863 to $US6687 and from $US2452 to $US13 543, respectively, compared with non-operated patients. The cost per life-year gained for kyphoplasty compared with vertebroplasty ranged from -$US4878 (cost saving) to $US2763. Among patients for whom surgical treatment was indicated, kyphoplasty was found to be cost effective, and perhaps even cost saving, compared with vertebroplasty. Even for the oldest patients (85 years of age and older), both interventions would be considered cost effective in terms of cost per life-year gained.

  10. Analysis of the premeability characteristics along rough-walled fractures using a homogenization method

    International Nuclear Information System (INIS)

    Chae, Byung Gon; Choi, Jung Hae; Ichikawa, Yasuaki; Seo, Yong Seok

    2012-01-01

    To compute a permeability coefficient along a rough fracture that takes into account the fracture geometry, this study performed detailed measurements of fracture roughness using a confocal laser scanning microscope, a quantitative analysis of roughness using a spectral analysis, and a homogenization analysis to calculate the permeability coefficient on the microand macro-scale. The homogenization analysis is a type of perturbation theory that characterizes the behavior of microscopically inhomogeneous material with a periodic boundary condition in the microstructure. Therefore, it is possible to analyze accurate permeability characteristics that are represented by the local effect of the fracture geometry. The Cpermeability coefficients that are calculated using the homogenization analysis for each rough fracture model exhibit an irregular distribution and do not follow the relationship of the cubic law. This distribution suggests that the permeability characteristics strongly depend on the geometric conditions of the fractures, such as the roughness and the aperture variation. The homogenization analysis may allow us to produce more accurate results than are possible with the preexisting equations for calculating permeability.

  11. Ductile fracture evaluation of ductile cast iron and forged steel by nonlinear-fracture-mechanics. Pt. 1. Tensile test by large scaled test pieces with surface crack

    International Nuclear Information System (INIS)

    Kosaki, Akio; Ajima, Tatsuro; Inohara, Yasuto

    1999-01-01

    The ductile fracture tests of Ductile Cast Iron and Forged Steel under a tensile stress condition were conducted using large-scaled flat test specimens with a surface crack and were evaluated by the J-integral values, in order to propose an evaluation method of initiation of ductile fracture of a cask body with crack by nonlinear-fracture-mechanics. Following results were obtained. 1) 1 -strain relations of Ductile Cast Iron and Forged Steel under the tensile stress condition were obtained, which is necessary for the development of J-integral design curves for evaluating the initiation of ductile fracture of the cask body. 2) In case of Ductile Cast Iron, the experimental J-integral values obtained from strain-gauges showed a good agreement with the linear-elastic-theory by Raju and Newman at room temperature, in both elastic and plastic regions. But, at 70degC in plastic region, the experimental i-integral values showed middle values between those predicted by the linear-elastic-theory and by the non- linear-elastic- theory (based on the fully plastic solution by Yagawa et al.). 3) In case of Forged Steel at both -25degC and room temperature, the experimental i-integral values obtained from strain-gauges showed a good agreement with those predicted by the linear-elastic-theory by Raju and Newman, in the elastic region. In the plastic region, however, the experimental i-integral values fell apart from the curve predicted by the linear-elastic-theory by Raju and Newman, and also approached to those by the non-linear-elastic-theory with increasing strain.(author)

  12. Analysis for preliminary evaluation of discrete fracture flow and large-scale permeability in sedimentary rocks

    International Nuclear Information System (INIS)

    Kanehiro, B.Y.; Lai, C.H.; Stow, S.H.

    1987-05-01

    Conceptual models for sedimentary rock settings that could be used in future evaluation and suitability studies are being examined through the DOE Repository Technology Program. One area of concern for the hydrologic aspects of these models is discrete fracture flow analysis as related to the estimation of the size of the representative elementary volume, evaluation of the appropriateness of continuum assumptions and estimation of the large-scale permeabilities of sedimentary rocks. A basis for preliminary analysis of flow in fracture systems of the types that might be expected to occur in low permeability sedimentary rocks is presented. The approach used involves numerical modeling of discrete fracture flow for the configuration of a large-scale hydrologic field test directed at estimation of the size of the representative elementary volume and large-scale permeability. Analysis of fracture data on the basis of this configuration is expected to provide a preliminary indication of the scale at which continuum assumptions can be made

  13. Carotenoids and risk of fracture: a meta-analysis of observational studies.

    Science.gov (United States)

    Xu, Jiuhong; Song, Chunli; Song, Xiaochao; Zhang, Xi; Li, Xinli

    2017-01-10

    To quantify the association between dietary and circulating carotenoids and fracture risk, a meta-analysis was conducted by searching MEDLINE and EMBASE databases for eligible articles published before May 2016. Five prospective and 2 case-control studies with 140,265 participants and 4,324 cases were identified in our meta-analysis. Among which 5 studies assessed the association between dietary carotenoids levels and hip fracture risk, 2 studies focused on the association between circulating carotenoids levels and any fracture risk. A random-effects model was employed to summarize the risk estimations and their 95% confidence intervals (CIs). Hip fracture risk among participants with high dietary total carotenoids intake was 28% lower than that in participants with low dietary total carotenoids (OR: 0.72; 95% CI: 0.51, 1.01). A similar risk of hip fracture was found for β-carotene based on 5 studies, the summarized OR for high vs. low dietary β-carotene was 0.72 (95% CI: 0.54, 0.95). However, a significant between-study heterogeneity was found (total carotene: I2 = 59.4%, P = 0.06; β-carotene: I2 = 74.4%, P = 0.04). Other individual carotenoids did not show significant associations with hip fracture risk. Circulating carotene levels had no significant association with any fracture risk, the pooled OR (95% CI) was 0.83 (0.59, 1.17). Based on the evidence from observational studies, our meta-analysis supported the hypothesis that higher dietary total carotenoids or β-carotene intake might be potentially associated with a low risk of hip fracture, however, future well-designed prospective cohort studies and randomized controlled trials are warranted to specify the associations between carotenoids and fracture.

  14. Numerical Analysis and Experimental Study of Hard Roofs in Fully Mechanized Mining Faces under Sleeve Fracturing

    Directory of Open Access Journals (Sweden)

    Zhitao Zheng

    2015-11-01

    Full Text Available Sudden falls of large-area hard roofs in a mined area release a large amount of elastic energy, generate dynamic loads, and cause disasters such as impact ground pressure and gas outbursts. To address these problems, in this study, the sleeve fracturing method (SFM was applied to weaken a hard roof. The numerical simulation software FLAC3D was used to develop three models based on an analysis of the SFM working mechanism. These models were applied to an analysis of the fracturing effects of various factors such as the borehole diameter, hole spacing, and sleeve pressure. Finally, the results of a simulation were validated using experiments with similar models. Our research indicated the following: (1 The crack propagation directions in the models were affected by the maximum principal stress and hole spacing. When the borehole diameter was fixed, the fracturing pressure increased with increasing hole spacing. In contrast, when the fracturing pressure was fixed, the fracturing range increased with increasing borehole diameter; (2 The most ideal fracturing effect was found at a fracturing pressure of 17.6 MPa in the model with a borehole diameter of 40 mm and hole spacing of 400 mm. The results showed that it is possible to regulate the falls of hard roofs using the SFM. This research may provide a theoretical basis for controlling hard roofs in mining.

  15. Analysis of size effect applicable to evaluation of fracture toughness of base metal for PWR vessel

    International Nuclear Information System (INIS)

    Benhamou, C.; Joly, P.; Andrieu, A.; Parrot, A.; Vidard, S.

    2015-01-01

    The objective of the present paper is to review the specimen size effect (also called crack front length effect) on Fracture Toughness of PWR Reactor Pressure Vessel Steel base metal. The analysis of the reality and amplitude of this effect is conducted in a first step on a database (the so-called GKSS database) including fracture toughness test results on a single representative material using specimens of different thicknesses, tested in the same temperature range. A realistic analytical form for describing the size effect observed in this data set is thus derived from statistical analyses and proposed for engineering application. In a second step, this size effect formulation is then applied to a large number of fracture toughness data, obtained in Irradiation Surveillance Programs, and also to the numerous data used for the definition of the ASME (and RCC-M) fracture toughness reference curves. This analysis allows normalizing all the available fracture toughness data with a single specimen width of 100 mm and defining the fracture toughness reference curve as the lower bound of this normalized set of data points. It is thus demonstrated that the fracture toughness reference curve is associated with a reference crack length of 100 mm, and can be used in RPV integrity analyses for other crack front length in association with the crack front length correction formula defined in the first step. (authors)

  16. Mapping and analysis of geological fractures extracted by remote sensing on Landsat TM images, example of the Imilchil-Tounfite area (Central High Atlas, Morocco)

    Energy Technology Data Exchange (ETDEWEB)

    Alaoui, H. El; Moujahid, El; Ibouh, H.; Bachnou, A.; Babram, M. Ait; Harti, A. EI

    2016-07-01

    The use of remote sensing, in this research, can be summarized in mapping and statistical studies of lineaments on the satellites images of the Jurassic outcrops in the Imilchil-Tounfite area, Central High Atlas of Morocco. This is to apply various manual techniques for extracting lineaments from Landsat TM image. Analytical techniques used in this work are: the principal component analysis (PCA) applied to selective bands of the visible and infrared, which allows creating new images with better visual interpretation. Directional filters N0°, N45°, N90°, and N135° with a 5×5 matrix were used to enhance lineaments in the corresponding perpendicular directions, and therefore to obtain a good discrimination of those structures. Preliminary results highlight a dominant geological fracturing trending ENE/WSW with 52% of the total lineaments, a second fracture trending is WNW/ESE at 23%, a third fracture series trending NE/SW with 20% and finally, a minor series of fractures trending NW/SE with 5% of the total lineaments. Distribution and statistical relationship, between fractures and the affected surface on the one hand and the fracture length on the other hand, shows a network of well-structured fractures. The final lineament map constitutes a contribution to complete the geology and assisting the mining and hydrogeological prospection, in the Imilchil-Tounfite area. (Author)

  17. Fracture analysis of a transversely isotropic high temperature superconductor strip based on real fundamental solutions

    Science.gov (United States)

    Gao, Zhiwen; Zhou, Youhe

    2015-04-01

    Real fundamental solution for fracture problem of transversely isotropic high temperature superconductor (HTS) strip is obtained. The superconductor E-J constitutive law is characterized by the Bean model where the critical current density is independent of the flux density. Fracture analysis is performed by the methods of singular integral equations which are solved numerically by Gauss-Lobatto-Chybeshev (GSL) collocation method. To guarantee a satisfactory accuracy, the convergence behavior of the kernel function is investigated. Numerical results of fracture parameters are obtained and the effects of the geometric characteristics, applied magnetic field and critical current density on the stress intensity factors (SIF) are discussed.

  18. Experimental and finite element analysis of fracture criterion in ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Birla Institute of Technology and Science, Pilani 333 031, India. 2 Research and ... The prevention of failure in stressed structural components currently ..... propagates. In the present work, a similar principle is extended to predict fracture limits using ... ASTM 1991 American Society for Testing and Materials (ASTM). E399-91 ...

  19. Discrete Dislocation Plasticity Analysis of Cracks and Fracture

    NARCIS (Netherlands)

    Giessen, Erik van der; Pippan, R; Gumbsch, P

    2010-01-01

    Fracture in plastically deforming crystals involves several length scales for cleavage-like crack growth. The relevant length scales range from that of the macroscale object to the atomic scale, including the various microstructural length scales in between that are associated with, for example,

  20. Fracture analysis of randomized implant-supported fixed dental prostheses

    Science.gov (United States)

    Esquivel-Upshaw, Josephine F.; Mehler, Alex; Clark, Arthur E.; Neal, Dan; Anusavice, Kenneth J.

    2014-01-01

    Objective Fractures of posterior fixed dental all-ceramic prostheses can be caused by one or more factors including prosthesis design, flaw distribution, direction and magnitude of occlusal loading, and nature of supporting infrastructure (tooth root/implant), and presence of adjacent teeth. This clinical study of implant-supported, all-ceramic fixed dental prostheses, determined the effects of (1) presence of a tooth distal to the most distal retainer; (2) prosthesis loading either along the non-load bearing or load bearing areas; (3) presence of excursive contacts or maximum intercuspation contacts in the prosthesis; and (4) magnitude of bite force on the occurrence of veneer ceramic fracture. Methods 89 implant-supported FDPs were randomized as either a three-unit posterior metal-ceramic (Au-Pd-Ag alloy and InLine POM, Ivoclar, Vivadent) FDP or a ceramic-ceramic (ZirCAD and ZirPress, Ivoclar, Vivadent) FDP. Two implants (Osseospeed, Dentsply) and custom abutments (Atlantis, Dentsply) supported these FDPs, which were cemented with resin cement (RelyX Universal Cement). Baseline photographs were made with markings of teeth from maximum intercuspation (MI) and excursive function. Patients were recalled at 6 months and 1 to 3 years. Fractures were observed, their locations recorded, and images compared with baseline photographs of occlusal contacts. Conclusion No significant relationship exists between the occurrence of fracture and: (1) the magnitude of bite force; (2) a tooth distal to the most distal retainer; and (3) contacts in load-bearing or non-load-bearing areas. However, there was a significantly higher likelihood of fracture in areas with MI contacts only. Clinical Significance This clinical study demonstrates that there is a need to evaluate occlusion differently with implant-supported prostheses than with natural tooth supported prostheses because of the absence of a periodontal ligament. Implant supported prostheses should have minimal occlusion and

  1. Fractal analysis of fractures and microstructures in rocks

    International Nuclear Information System (INIS)

    Merceron, T.; Nakashima, S.; Velde, B.; Badri, A.

    1991-01-01

    Fractal geometry was used to characterize the distribution of fracture fields in rocks, which represent main pathways for material migration such as groundwater flow. Fractal investigations of fracture distribution were performed on granite along Auriat and Shikoku boreholes. Fractal dimensions range between 0.3 and 0.5 according to the different sets of fracture planes selected for the analyses. Shear, tension and compressional modes exhibit different fractal values while the composite fracture patterns are also fractal but with a different, median, fractal value. These observations indicate that the fractal method can be used to distinguish fracture types of different origins in a complex system. Fractal results for Shikoku borehole also correlate with geophysical parameters recorded along, drill-holes such as resistivity and possibly permeability. These results represent the first steps of the fractal investigation along drill-holes. Future studies will be conducted to verify relationships between fractal dimensions and permeability by using available geophysical data. Microstructures and microcracks were analysed in the Inada granite. Microcrack patterns are fractal but fractal dimensions values vary according to both mineral type and orientations of measurement within the mineral. Microcracks in quartz are characterized by more irregular distribution (average D = 0.40) than those in feldspars (D = 0.50) suggesting a different mode of rupture. Highest values of D are reported along main cleavage planes for feldspars or C axis for quartz. Further fractal investigations of microstructure in granite will be used to characterize the potential pathways for fluid migration and diffusion in the rock matrix. (author)

  2. Using decision analysis to assess comparative clinical efficacy of surgical treatment of unstable ankle fractures.

    Science.gov (United States)

    Michelson, James D

    2013-11-01

    The development of a robust treatment algorithm for ankle fractures based on well-established stability criteria has been shown to be prognostic with respect to treatment and outcomes. In parallel with the development of improved understanding of the biomechanical rationale of ankle fracture treatment has been an increased emphasis on assessing the effectiveness of medical and surgical interventions. The purpose of this study was to investigate the use of using decision analysis in the assessment of the cost effectiveness of operative treatment of ankle fractures based on the existing clinical data in the literature. Using the data obtained from a previous structured review of the ankle fracture literature, decision analysis trees were constructed using standard software. The decision nodes for the trees were based on ankle fracture stability criteria previously published. The outcomes were assessed by calculated Quality-Adjusted Life Years (QALYs) assigned to achieving normal ankle function, developing posttraumatic arthritis, or sustaining a postoperative infection. Sensitivity analysis was undertaken by varying the patient's age, incidence of arthritis, and incidence or infection. Decision analysis trees captured the essential aspects of clinical decision making in ankle fracture treatment in a clinically useful manner. In general, stable fractures yielded better outcomes with nonoperative treatment, whereas unstable fractures had better outcomes with surgery. These were consistent results over a wide range of postoperative infection rates. Varying the age of the patient did not qualitatively change the results. Between the ages of 30 and 80 years, surgery yielded higher expected QALYs than nonoperative care for unstable fractures, and generated lower QALYs than nonoperative care for stable fractures. Using local cost estimates for operative and nonoperative treatment, the incremental cost of surgery for unstable fractures was less than $40,000 per QALY (the

  3. Does Alendronate reduce the risk of fracture in men? A meta-analysis incorporating prior knowledge of anti-fracture efficacy in women

    Directory of Open Access Journals (Sweden)

    Papaioannou Alexandra

    2005-07-01

    Full Text Available Abstract Background Alendronate has been found to reduce the risk of fractures in postmenopausal women as demonstrated in multiple randomized controlled trials enrolling thousands of women. Yet there is a paucity of such randomized controlled trials in osteoporotic men. Our objective was to systematically review the anti-fracture efficacy of alendronate in men with low bone mass or with a history of prevalent fracture(s and incorporate prior knowledge of alendronate efficacy in women in the analysis. Methods We examined randomized controlled trials in men comparing the anti-fracture efficacy of alendronate to placebo or calcium or vitamin D, or any combination of these. Studies of men with secondary causes of osteoporosis other than hypogonadism were excluded. We searched the following electronic databases (without language restrictions for potentially relevant citations: Medline, Medline in Process (1966-May 24/2004, and Embase (1996–2004. We also contacted the manufacturer of the drug in search of other relevant trials. Two reviewers independently identified two trials (including 375 men, which met all inclusion criteria. Data were abstracted by one reviewer and checked by another. Results of the male trials were pooled using Bayesian random effects models, incorporating prior information of anti-fracture efficacy from meta-analyses of women. Results The odds ratios of incident fractures in men (with 95% credibility intervals with alendronate (10 mg daily were: vertebral fractures, 0.44 (0.23, 0.83 and non-vertebral fractures, 0.60 (0.29, 1.44. Conclusion In conclusion, alendronate decreases the risk of vertebral fractures in men at risk. There is currently insufficient evidence of a statistically significant reduction of non-vertebral fractures, but the paucity of trials in men limit the statistical power to detect such an effect.

  4. Finite element analysis and fracture resistance testing of a new intraradicular post

    Directory of Open Access Journals (Sweden)

    Eron Toshio Colauto Yamamoto

    2012-08-01

    Full Text Available OBJECTIVES: The objective of the present study was to evaluate a prefabricated intraradicular threaded pure titanium post, designed and developed at the São José dos Campos School of Dentistry - UNESP, Brazil. This new post was designed to minimize stresses observed with prefabricated post systems and to improve cost-benefits. MATERIAL AND METHODS: Fracture resistance testing of the post/core/root complex, fracture analysis by microscopy and stress analysis by the finite element method were used for post evaluation. The following four prefabricated metal post systems were analyzed: group 1, experimental post; group 2, modification of the experimental post; group 3, Flexi Post, and group 4, Para Post. For the analysis of fracture resistance, 40 bovine teeth were randomly assigned to the four groups (n=10 and used for the fabrication of test specimens simulating the situation in the mouth. The test specimens were subjected to compressive strength testing until fracture in an EMIC universal testing machine. After fracture of the test specimens, their roots were sectioned and analyzed by microscopy. For the finite element method, specimens of the fracture resistance test were simulated by computer modeling to determine the stress distribution pattern in the post systems studied. RESULTS: The fracture test presented the following averages and standard deviation: G1 (45.63±8.77, G2 (49.98±7.08, G3 (43.84±5.52, G4 (47.61±7.23. Stress was homogenously distributed along the body of the intraradicular post in group 1, whereas high stress concentrations in certain regions were observed in the other groups. These stress concentrations in the body of the post induced the same stress concentration in root dentin. CONCLUSIONS: The experimental post (original and modified versions presented similar fracture resistance and better results in the stress analysis when compared with the commercial post systems tested (08/2008-PA/CEP.

  5. Bending strength and fracture surface topography of natural fiber-reinforced shell for investment casting process

    Directory of Open Access Journals (Sweden)

    Kai Lu

    2016-05-01

    Full Text Available In order to improve the properties of silica sol shell for investment casting process, various contents of cattail fibers were added into the slurry to prepare a fiber-reinforced shell in the present study. The bending strength of fiber-reinforced shell was investigated and the fracture surfaces of shell specimens were observed using SEM. It is found that the bending strength increases with the increase of fiber content, and the bending strength of a green shell with 1.0 wt.% fiber addition increases by 44% compared to the fiber-free shell. The failure of specimens of the fiber-reinforced green shell results from fiber rupture and debonding between the interface of fibers and adhesive under the bending load. The micro-crack propagation in the matrix is inhibited by the micro-holes for ablation of fibers in specimens of the fiber-reinforced shell during the stage of being fired. As a result, the bending strength of specimens of the fired shell had no significant drop. Particularly, the bending strength of specimens of the fired shell reinforced with 0.6wt.% fiber reached the maximum value of 4.6 MPa.

  6. Mechanical strength and analysis of fracture of titanium joining submitted to laser and tig welding

    Directory of Open Access Journals (Sweden)

    Ana Cláudia Gabrielli Piveta

    2012-12-01

    Full Text Available This study compared the tensile strength and fracture mechanism of tungsten inert gas (TIG welds in cylindrical rods of commercially pure titanium (cp Ti with those of laser welds and intact samples. Thirty dumbbell-shaped samples were developed by using brass rods as patterns. The samples were invested in casings, subjected to thermal cycles, and positioned in a plasma arc welding machine under argon atmosphere and vacuum, and titanium was injected under vacuum/pressure. The samples were X-rayed to detect possible welding flaws and randomly assigned to three groups to test the tensile strength and the fracture mechanism: intact, laser welding, and TIG welding. The tensile test results were investigated using ANOVA, which indicated that the samples were statistically similar. The fracture analysis showed that the cpTi samples subjected to laser welding exhibited brittle fracture and those subjected to TIG welding exhibited mixed brittle/ductile fracture with a predominance of ductile fracture with the presence of microcavities and cleavage areas. Intact samples presented the characteristic straightening in the fracture areas, indicating the ductility of the material.

  7. A Mathematical Pressure Transient Analysis Model for Multiple Fractured Horizontal Wells in Shale Gas Reservoirs

    Directory of Open Access Journals (Sweden)

    Yan Zeng

    2018-01-01

    Full Text Available Multistage fractured horizontal wells (MFHWs have become the main technology for shale gas exploration. However, the existing models have neglected the percolation mechanism in nanopores of organic matter and failed to consider the differences among the reservoir properties in different areas. On that account, in this study, a modified apparent permeability model was proposed describing gas flow in shale gas reservoirs by integrating bulk gas flow in nanopores and gas desorption from nanopores. The apparent permeability was introduced into the macroseepage model to establish a dynamic pressure analysis model for MFHWs dual-porosity formations. The Laplace transformation and the regular perturbation method were used to obtain an analytical solution. The influences of fracture half-length, fracture permeability, Langmuir volume, matrix radius, matrix permeability, and induced fracture permeability on pressure and production were discussed. Results show that fracture half-length, fracture permeability, and induced fracture permeability exert a significant influence on production. A larger Langmuir volume results in a smaller pressure and pressure derivative. An increase in matrix permeability increases the production rate. Besides, this model fits the actual field data relatively well. It has a reliable theoretical foundation and can preferably describe the dynamic changes of pressure in the exploration process.

  8. X-ray fractography by using synchrotron radiation source. Residual stress distribution just beneath fatigue fracture surface

    International Nuclear Information System (INIS)

    Akita, Koichi; Yoshioka, Yasuo; Suzuki, Hiroshi; Sasaki, Toshihiko

    2000-01-01

    The residual stress distributions just beneath the fatigue fracture surface were measured using synchrotron radiation with three different wavelengths, i.e., three different penetration depths. The residual stress distributions were estimated from three kinds of diffraction data by the following process. First, a temporary residual stress distribution in the depth direction is assumed. Theoretical 2θ-sin 2 ψ diagrams for each wavelength, where each has a different penetration depth, are calculated by the cosψ method developed by one of the authors. The sum total of the differences between the theoretical and experimental values of the diffraction angle in 2θ-sin 2 ψ diagrams is calculated. This total value is minimized by changing the assumed stress distribution by the quasi-Newton optimization method. Finally, optimized 2θ-sin 2 ψ diagrams for each penetration depth and detailed stress distribution are determined. The true surface residual stress is obtained from this stress distribution. No effect of load ratio R (= P min /P max ) on the residual stresses of the fatigue fracture surfaces in low-carbon steels was observed when the sin 2 ψ method was used for stress measurement. However, the residual stresses became higher with increasing R when these were measured by the proposed method. On the basis of this, the stress intensity factor range, ΔK, can be estimated from the residual stress on the fatigue fracture surface. (author)

  9. [Effect factors analysis of knee function recovery after distal femoral fracture operation].

    Science.gov (United States)

    Bei, Chaoyong; Wang, Ruiying; Tang, Jicun; Li, Qiang

    2009-09-01

    To investigate the effect factors of knee function recovery after operation in distal femoral fractures. From January 2001 to May 2007, 92 cases of distal femoral fracture were treated. There were 50 males and 42 females, aged 20-77 years old (average 46.7 years old). Fracture was caused by traffic accident in 48 cases, by falling from height in 26 cases, by bruise in 12 cases and by tumble in 6 cases. According to Müller's Fracture classification, there were 29 cases of type A, 12 cases of type B and 51 cases of type C. According to American Society of Anesthesiologists (ASA) classification, there were 21 cases of grade I, 39 cases of grade II, 24 cases of grade III, and 8 cases of grade IV. The time from injury to operation was 4 hours to 24 days with an average of 7 days. Anatomical plate was used in 43 cases, retrograde interlocking intramedullary nail in 37 cases, and bone screws, bolts and internal fixation with Kirschner pins in 12 cases. After operation, the HSS knee function score was used to evaluate efficacy. Ten related factors were applied for statistical analysis, to knee function recovery after operation in distal femoral fractures, such as age, sex, preoperative ASA classification, injury to surgery time, fracture type, treatment, reduction quality, functional exercise after operation, whether or not CPM functional training and postoperative complications. Wound healed by first intention in 88 cases, infection occurred in 4 cases. All patients followed up 16-32 months with an average of 23.1 months. Clinical union of fracture was achieved within 3-7 months after operation. Extensor device adhesions and the scope of activities of fracture displacement in 6 cases, mild knee varus or valgus in 7 cases and implant loosening in 6 cases. According to HSS knee function score, the results were excellent in 52 cases, good in 15 cases, fair in 10 cases and poor in 15 cases with an excellent and good rate of 72.83%. Single factor analysis showed that age

  10. Analysis and experimental validation of through-thickness cracked large-scale biaxial fracture tests

    International Nuclear Information System (INIS)

    Wiesner, C.S.; Goldthorpe, M.R.; Andrews, R.M.; Garwood, S.J.

    1999-01-01

    Since 1984 TWI has been involved in an extensive series of tests investigating the effects of biaxial loading on the fracture behaviour of A533B steel. Testing conditions have ranged from the lower to upper shelf regions of the transition curve and covered a range of biaxiality ratios. In an attempt to elucidate the trends underlying the experimental results, finite element-based mechanistic models were used to analyse the effects of biaxial loading. For ductile fracture, a modified Gunson model was used and important effects on tearing behaviour were found for through thickness cracked wide plates, as observed in upper shelf tests. For cleavage fracture, both simple T-stress methods and the Anderson-Dodds and Beremin models were used. Whilst the effect of biaxiality on surface cracked plates was small, a marked effect of biaxial loading was found for the through-thickness crack. To further validate the numerical predictions for cleavage fracture, TWI have performed an additional series of lower shelf through thickness cracked biaxial wide plate fracture tests. These tests were performed using various biaxiality loading conditions varying from simple uniaxial loading, through equibiaxial loading, to a biaxiality ratio equivalent to a circumferential crack in a pressure vessel. These tests confirmed the predictions that there is a significant effect of biaxial loading on cleavage fracture of through thickness cracked plate. (orig.)

  11. Comparative analysis of deterministic and probabilistic fracture mechanical assessment tools

    Energy Technology Data Exchange (ETDEWEB)

    Heckmann, Klaus [Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) gGmbH, Koeln (Germany); Saifi, Qais [VTT Technical Research Centre of Finland, Espoo (Finland)

    2016-11-15

    Uncertainties in material properties, manufacturing processes, loading conditions and damage mechanisms complicate the quantification of structural reliability. Probabilistic structure mechanical computing codes serve as tools for assessing leak- and break probabilities of nuclear piping components. Probabilistic fracture mechanical tools were compared in different benchmark activities, usually revealing minor, but systematic discrepancies between results of different codes. In this joint paper, probabilistic fracture mechanical codes are compared. Crack initiation, crack growth and the influence of in-service inspections are analyzed. Example cases for stress corrosion cracking and fatigue in LWR conditions are analyzed. The evolution of annual failure probabilities during simulated operation time is investigated, in order to identify the reasons for differences in the results of different codes. The comparison of the tools is used for further improvements of the codes applied by the partners.

  12. Impact and fracture analysis of fish scales from Arapaima gigas.

    Science.gov (United States)

    Torres, F G; Malásquez, M; Troncoso, O P

    2015-06-01

    Fish scales from the Amazonian fish Arapaima gigas have been characterised to study their impact and fracture behaviour at three different environmental conditions. Scales were cut in two different directions to analyse the influence of the orientation of collagen layers. The energy absorbed during impact tests was measured for each sample and SEM images were taken after each test in order to analyse the failure mechanisms. The results showed that scales tested at cryogenic temperatures display fragile behaviour, while scales tested at room temperature did not fracture. Different failure mechanisms have been identified, analysed and compared with the failure modes that occur in bone. The impact energy obtained for fish scales was two to three times higher than the values reported for bone in the literature. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Depression and risk of fracture and bone loss: an updated meta-analysis of prospective studies.

    Science.gov (United States)

    Wu, Q; Liu, B; Tonmoy, S

    2018-03-12

    This meta-analysis pooled results from 23 qualifying individual cohort studies and found that depression was significantly associated with an increased risk of fractures and bone loss. The association between depression and risk of fracture remains controversial. We conducted a comprehensive meta-analysis to examine the effect of depression on the risk of osteoporotic fractures and bone loss. We searched databases and reviewed citations in relevant articles for eligible cohort studies. Two investigators independently conducted study selection, appraisal, and data abstraction through the use of a standardized protocol. Random effect models were used for meta-analysis. Cochrane Q and I 2 statistics were used to assess heterogeneity. Funnel plots and rank correlation tests were used to evaluate publication bias. Twenty-three studies were included for meta-analysis. In studies that reported hazard ratio (HR) as the outcome (nine studies [n = 309,862]), depression was associated with 26% increase in fracture risk (HR = 1.26, 95% CI, 1.10-1.43, p meta-analysis having modified inclusion criteria and in different subgroup analyses as well. Significant heterogeneity was observed in the meta-analysis; however, no significant publication bias was detected. Depression is associated with a significant increased risk in fracture and bone loss. Effective prevention may decrease such risk.

  14. Dynamic Mechanical Properties and Fracture Surface Morphologies of Core-Shell Rubber (CSR) Toughened Epoxy at Liquid Nitrogen (Ln2) Temperatures

    Science.gov (United States)

    Wang, J.; Magee, D.; Schneider, J. A.

    2009-01-01

    The dynamic mechanical properties and fracture surface morphologies were evaluated for a commercial epoxy resin toughened with two types of core-shell rubber (CSR) toughening agents (Kane Ace(Registered TradeMark) MX130 and MX960). The impact resistance (R) was evaluated by the resulting breaking energy measured in Charpy impact tests conducted on an instrumented drop tower. The resulting fracture surface morphologies were examined using Scanning Electron Microscopy (SEM). Fractographic observations of the CSR toughened epoxy tested at ambient temperature, showed a fracture as characterized by slender dendrite textures with large voids. The increasing number of dendrites and decreasing size of scale-like texture with more CSR particles corresponded with increased R. As the temperature decreased to Liquid Nitrogen (LN 2), the fracture surfaces showed a fracture characterized by a rough, torn texture containing many river markings and deep furrows.

  15. Type III odontoid fractures: A subgroup analysis of complex, high-energy fractures treated with external immobilization

    Directory of Open Access Journals (Sweden)

    Thomas E Niemeier

    2018-01-01

    Conclusions: Complex Type III odontoid fractures are distinctly different from low-energy injuries. In the current study, 21% of patients were unsuccessfully treated nonoperatively with external immobilization and required surgery. For complex Type III fractures, we recommend initial conservative treatment, while maintaining close monitoring throughout patient recovery and fracture union.

  16. Fracture analysis of a transversely isotropic high temperature superconductor strip based on real fundamental solutions

    International Nuclear Information System (INIS)

    Gao, Zhiwen; Zhou, Youhe

    2015-01-01

    Highlights: • We studied fracture problem in HTS based on real fundamental solutions. • When the thickness of HTS strip increases the SIF decrease. • A higher applied field leads to a larger stress intensity factor. • The greater the critical current density is, the smaller values of the SIF is. - Abstract: Real fundamental solution for fracture problem of transversely isotropic high temperature superconductor (HTS) strip is obtained. The superconductor E–J constitutive law is characterized by the Bean model where the critical current density is independent of the flux density. Fracture analysis is performed by the methods of singular integral equations which are solved numerically by Gauss–Lobatto–Chybeshev (GSL) collocation method. To guarantee a satisfactory accuracy, the convergence behavior of the kernel function is investigated. Numerical results of fracture parameters are obtained and the effects of the geometric characteristics, applied magnetic field and critical current density on the stress intensity factors (SIF) are discussed

  17. Use of Pressure-Redistributing Support Surfaces among Elderly Hip Fracture Patients across the Continuum of Care: Adherence to Pressure Ulcer Prevention Guidelines

    Science.gov (United States)

    Baumgarten, Mona; Margolis, David; Orwig, Denise; Hawkes, William; Rich, Shayna; Langenberg, Patricia; Shardell, Michelle; Palmer, Mary H.; McArdle, Patrick; Sterling, Robert; Jones, Patricia S.; Magaziner, Jay

    2010-01-01

    Purpose: To estimate the frequency of use of pressure-redistributing support surfaces (PRSS) among hip fracture patients and to determine whether higher pressure ulcer risk is associated with greater PRSS use. Design and Methods: Patients (n = 658) aged [greater than or equal] 65 years who had surgery for hip fracture were examined by research…

  18. Interpretation of Microseismicity Observed From Surface and Borehole Seismic Arrays During Hydraulic Fracturing in Shale - Bedding Plane Slip Model

    Science.gov (United States)

    Stanek, F.; Jechumtalova, Z.; Eisner, L.

    2017-12-01

    We present a geomechanical model explaining microseismicity induced by hydraulic fracturing in shales developed from many datasets acquired with two most common types of seismic monitoring arrays, surface and dual-borehole arrays. The geomechanical model explains the observed source mechanisms and locations of induced events from two stimulated shale reservoirs. We observe shear dip-slip source mechanisms with nodal planes aligned with location trends. We show that such seismicity can be explained as a shearing along bedding planes caused by aseismic opening of vertical hydraulic fractures. The source mechanism inversion was applied only to selected high-quality events with sufficient signal-to-noise ratio. We inverted P- and P- and S-wave arrival amplitudes to full-moment tensor and decomposed it to shear, volumetric and compensated linear vector dipole components. We also tested an effect of noise presented in the data to evaluate reliability of non-shear components. The observed seismicity from both surface and downhole monitoring of shale stimulations is very similar. The locations of induced microseismic events are limited to narrow depth intervals and propagate along distinct trend(s) showing fracture propagation in direction of maximum horizontal stress from injection well(s). The source mechanisms have a small non-shear component which can be partly explained as an effect of noise in the data, i.e. events represent shearing on faults. We observe predominantly dip-slip events with a strike of the steeper (almost vertical) nodal plane parallel to the fracture propagation. Therefore the other possible nodal plane is almost horizontal. The rake angles of the observed mechanisms divide these dip-slips into two groups with opposite polarities. It means that we observe opposite movements on the nearly identically oriented faults. Realizing a typical structural weakness of shale in horizontal planes, we interpret observed microseismicity as a result of shearing

  19. Immediate versus delayed intramedullary nailing for open fractures of the tibial shaft: a multivariate analysis of factors affecting deep infection and fracture healing.

    Science.gov (United States)

    Yokoyama, Kazuhiko; Itoman, Moritoshi; Uchino, Masataka; Fukushima, Kensuke; Nitta, Hiroshi; Kojima, Yoshiaki

    2008-10-01

    The purpose of this study was to evaluate contributing factors affecting deep infection and fracture healing of open tibia fractures treated with locked intramedullary nailing (IMN) by multivariate analysis. We examined 99 open tibial fractures (98 patients) treated with immediate or delayed locked IMN in static fashion from 1991 to 2002. Multivariate analyses following univariate analyses were derived to determine predictors of deep infection, nonunion, and healing time to union. The following predictive variables of deep infection were selected for analysis: age, sex, Gustilo type, fracture grade by AO type, fracture location, timing or method of IMN, reamed or unreamed nailing, debridement time (6 h), method of soft-tissue management, skin closure time (1 week), existence of polytrauma (ISS or =18), existence of floating knee injury, and existence of superficial/pin site infection. The predictive variables of nonunion selected for analysis was the same as those for deep infection, with the addition of deep infection for exchange of pin site infection. The predictive variables of union time selected for analysis was the same as those for nonunion, excluding of location, debridement time, and existence of floating knee and superficial infection. Six (6.1%; type II Gustilo n=1, type IIIB Gustilo n=5) of the 99 open tibial fractures developed deep infections. Multivariate analysis revealed that timing or method of IMN, debridement time, method of soft-tissue management, and existence of superficial or pin site infection significantly correlated with the occurrence of deep infection (Prate in type IIIB + IIIC was significantly higher than those in type I + II and IIIA (P = 0.016). Nonunion occurred in 17 fractures (20.3%, 17/84). Multivariate analysis revealed that Gustilo type, skin closure time, and existence of deep infection significantly correlated with occurrence of nonunion (P < 0.05). Gustilo type and existence of deep infection were significantly correlated

  20. Global Analysis of Minimal Surfaces

    CERN Document Server

    Dierkes, Ulrich; Tromba, Anthony J

    2010-01-01

    Many properties of minimal surfaces are of a global nature, and this is already true for the results treated in the first two volumes of the treatise. Part I of the present book can be viewed as an extension of these results. For instance, the first two chapters deal with existence, regularity and uniqueness theorems for minimal surfaces with partially free boundaries. Here one of the main features is the possibility of 'edge-crawling' along free parts of the boundary. The third chapter deals with a priori estimates for minimal surfaces in higher dimensions and for minimizers of singular integ

  1. Deposition behavior of polystyrene latex particles on solid surfaces during migration through an artificial fracture in a granite rock sample

    International Nuclear Information System (INIS)

    Chinju, Hirofumi; Tanaka, Satoru; Kuno, Yoshio

    2001-01-01

    The deposition behavior of colloids during transport through heterogeneous media was observed by conducting column experiments to study migration of polystyrene latex particles (diameter=309 nm) through columns packed with artificially fractured granite rock (length=300 and 150 mm). The experiments were conducted under conditions of different ionic strengths and flow rates. The results were similar to those for colloid deposition in columns packed with glass beads reported previously; the colloid breakthrough curves showed three stages, characterized by different rates of change in the concentration of effluent. Colloid deposition on the fracture surfaces was described by considering strong and weak deposition sites. Scanning Electron Microscopy (SEM) observations indicated the existence of strong and weak sites on the fracture surfaces regardless of mineral composition. The observations also showed that the strong deposition sites tended to exist on surface irregularities such as cracks or protrusions. The degree of colloid deposition increased with increasing ionic strength and decreasing flow rate. The dependencies on ionic strength and flow rate agreed qualitatively with the DLVO theory and the previous experimental results, respectively. (author)

  2. In situ observation of fluoride-ion-induced hydroxyapatite-collagen detachment on bone fracture surfaces by atomic force microscopy

    International Nuclear Information System (INIS)

    Kindt, J H; Thurner, P J; Lauer, M E; Bosma, B L; Schitter, G; Fantner, G E; Izumi, M; Weaver, J C; Morse, D E; Hansma, P K

    2007-01-01

    The topography of freshly fractured bovine and human bone surfaces was determined by the use of atomic force microscopy (AFM). Fracture surfaces from both kinds of samples exhibited complex landscapes formed by hydroxyapatite mineral platelets with lateral dimensions ranging from ∼90 nm x 60 nm to ∼20 nm x 20 nm. Novel AFM techniques were used to study these fracture surfaces during various chemical treatments. Significant topographical changes were observed following exposure to aqueous solutions of ethylenediaminetetraacetic acid (EDTA) or highly concentrated sodium fluoride (NaF). Both treatments resulted in the apparent loss of the hydroxyapatite mineral platelets on a timescale of a few seconds. Collagen fibrils situated beneath the overlying mineral platelets were clearly exposed and could be resolved with high spatial resolution in the acquired AFM images. Time-dependent mass loss experiments revealed that the applied agents (NaF or EDTA) had very different resulting effects. Despite the fact that the two treatments exhibited nearly identical results following examination by AFM, bulk bone samples treated with EDTA exhibited a ∼70% mass loss after 72 h, whereas for the NaF-treated samples, the mass loss was only of the order of ∼10%. These results support those obtained from previous mechanical testing experiments, suggesting that enhanced formation of superficial fluoroapatite dramatically weakens the protein-hydroxyapatite interfaces. Additionally, we discovered that treatment with aqueous solutions of NaF resulted in the effective extraction of noncollagenous proteins from bone powder

  3. Thin film surface reconstruction analysis

    Energy Technology Data Exchange (ETDEWEB)

    Imperatori, P [CNR, Monterotondo Stazione, Rome (Italy). Istituto di Chimica dei materiali

    1996-09-01

    The study of the atomic structure of surfaces and interfaces is a fundamental step in the knowledge and the development of new materials. Among the several surface-sensitive techniques employed to characterise the atomic arrangements, grazing incidence x-ray diffraction (GIXD) is one of the most powerful. With a simple data treatment, based on the kinematical theory, and using the classical methods of x-ray bulk structure determination, it gives the atomic positions of atoms at a surface or an interface and the atomic displacements of subsurface layers for a complete determination of the structure. In this paper the main features of the technique will be briefly reviewed and selected of application to semiconductor and metal surfaces will be discussed.

  4. Gap Surface Plasmon Waveguide Analysis

    DEFF Research Database (Denmark)

    Nielsen, Michael Grøndahl; Bozhevolnyi, Sergey I.

    2014-01-01

    Plasmonic waveguides supporting gap surface plasmons (GSPs) localized in a dielectric spacer between metal films are investigated numerically and the waveguiding properties at telecommunication wavelengths are presented. Especially, we emphasize that the mode confinement can advantageously...

  5. Comparison of Neck Screw and Conventional Fixation Techniques in Mandibular Condyle Fractures Using 3-Dimensional Finite Element Analysis.

    Science.gov (United States)

    Conci, Ricardo Augusto; Tomazi, Flavio Henrique Silveira; Noritomi, Pedro Yoshito; da Silva, Jorge Vicente Lopes; Fritscher, Guilherme Genehr; Heitz, Claiton

    2015-07-01

    To compare the mechanical stress on the mandibular condyle after the reduction and fixation of mandibular condylar fractures using the neck screw and 2 other conventional techniques according to 3-dimensional finite element analysis. A 3-dimensional finite element model of a mandible was created and graphically simulated on a computer screen. The model was fixed with 3 different techniques: a 2.0-mm plate with 4 screws, 2 plates (1 1.5-mm plate and 1 2.0-mm plate) with 4 screws, and a neck screw. Loads were applied that simulated muscular action, with restrictions of the upper movements of the mandible, differentiation of the cortical and medullary bone, and the virtual "folds" of the plates and screws so that they could adjust to the condylar surface. Afterward, the data were exported for graphic visualization of the results and quantitative analysis was performed. The 2-plate technique exhibited better stability in regard to displacement of fractures, deformity of the synthesis materials, and minimum and maximum tension values. The results with the neck screw were satisfactory and were similar to those found when a miniplate was used. Although the study shows that 2 isolated plates yielded better results compared with the other groups using other fixation systems and methods, the neck screw could be an option for condylar fracture reduction. Copyright © 2015 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  6. Effect of boundary conditions on the strength and deformability of replicas of natural fractures in welded tuff: Data analysis

    International Nuclear Information System (INIS)

    Wibowo, J.; Amadei, B.; Sture, S.

    1994-04-01

    Assessing the shear behavior of intact rock ampersand rock fractures is an important issue in the design of a potential nuclear waste repository at Yucca Mountain Nevada. Cyclic direct shear experiments were conducted on replicas of three natural fractures and a laboratory-developed tensile fracture of welded tuff. The tests were carried out under constant normal loads or constant normal stiffnesses with different initial normal load levels. Each test consisted of five cycles of forward and reverse shear motion. Based on the results of the shear tests conducted under constant normal load, the shear behavior of the joint replicas tested under constant normal stiffness was predicted by using the graphical analysis method of Saeb (1989), and Amadei and Saeb (1990). Comparison between the predictions and the actual constant stiffness direct shear experiment results can be found in a report by Wibowo et al. (1993b). Results of the constant normal load shear experiments are analyzed using several constitutive models proposed in the rock mechanics literature for joint shear strength, dilatancy, and joint surface damage. It is shown that some of the existing models have limitations. New constitutive models are proposed and are included in a mathematical analysis tool that can be used to predict joint behavior under various boundary conditions

  7. Potential effect of fracture technology on IPTS [Integrated Pressurized Thermal Shock] analysis (Fracture toughness: Kla and Klc and warm prestressing)

    International Nuclear Information System (INIS)

    Dickson, T.L.

    1990-01-01

    A major nuclear plant life extension issue to be confronted in the 1990's is pressure vessel integrity for the pressurized thermal shock (PTS) loading condition. Governing criteria associated with PTS are included in ''The PTS Rule'' (10 CFR 50.61) and Regulatory Guide 1.154: Format and Content of Plant-Specific Pressurized Thermal Shock Safety Analysis Reports for Pressurized Water Reactors. The results of the Integrated Pressurized Water Reactors. The results of the Integrated Pressurized Thermal Shock (IPTS) Program, along with risk assessments and fracture analyses performed by the NRC and reactor system vendors, contributed to the derivation of the PTS Rule. Over the last several years, the Heavy Section Steel Technology (HSST) Program at the Oak Ridge National Laboratory (ORNL) has performed a series of large-scale fracture-mechanics experiments. The Thermal Shock Experiments (TSE), Pressurized Thermal Shock Experiments (PTSE), and Wide Plate Experiments (WPE) produced K IC and K Ia data that suggest increased mean K IC and K Ia curves relative to the ones used in the IPTS study. Also, the PTSE and WPE have demonstrated that prototypical nuclear reactor pressure vessel steels are capable of arresting a propagating crack at K I values considerably above 220 MPa√m, the implicit limit of the ASME Code and the limit used in the IPTS studies. This document provides a discussion of the results of these experiments

  8. Risk of fracture with thiazolidinediones: an individual patient data meta-analysis

    Directory of Open Access Journals (Sweden)

    Marloes T Bazelier

    2013-02-01

    Full Text Available Background: The use of thiazolidinediones (TZDs has been associated with increased fracture risks. Our aim was to estimate the risk of fracture with TZDs in three different healthcare registries, using exactly the same study design, and to perform an individual patient data meta-analysis of these three studies. Methods: Population-based cohort studies were performed utilizing the British General Practice Research Database (GPRD, the Dutch PHARMO Record Linkage System, and the Danish National Health Registers. In all three databases, the exposed cohort consisted of all patients (aged 18+ with at least one prescription of antidiabetic (AD medication. Cox proportional hazards models were used to estimate hazard ratios (HRs of fracture. The total period of follow-up for each patient was divided into periods of current exposure and past exposure, with patients moving between current and past use.Results: In all three registries, the risk of fracture was increased for women who were exposed to TZDs: HR 1.48 [1.37-1.60] in GPRD, HR 1.35 [1.15-1.58] in PHARMO and HR 1.22 [1.03-1.44] in Denmark. Combining the data in an individual patient data meta-analysis resulted, for women, in a 1.4-fold increased risk of any fracture for current TZD users versus other AD drug users (adj. HR 1.44 [1.35-1.53]. For men, there was no increased fracture risk (adj. HR 1.05 [0.96-1.14]. Risks were increased for fractures of the radius/ulna, humerus, tibia/fibula, ankle and foot, but not for hip/femur or vertebral fractures. Current TZD users with more than 25 TZD presciptions ever before had a 1.6-fold increased risk of fracture compared with other AD drug users (HR 1.59 [1.46-1.74].Conclusion: In this study, we consistently found a 1.2- to 1.5-fold increased risk of fractures for women using TZDs, but not for men, across three different healthcare registries. TZD users had an increased risk for fractures of the extremities, and risks further increased for prolonged users

  9. Fracture strength of fiber-reinforced surface-retained anterior cantilever restorations

    NARCIS (Netherlands)

    Oezcan, Mutlu; Kumbuloglu, Ovul; User, Atilla

    2008-01-01

    Purpose: This study compared the fracture strength of direct anterior cantilever fiber-reinforced composite (FRC) fixed partial dentures (FPD) reinforced with 3 types of E-glass fibers preimpregnated with either urethane tetramethacrylate, bisphenol glycidylmethacrylate/polymethyl methacrylate, or

  10. Geophysical characterization of the role of fault and fracture systems for recharging groundwater aquifers from surface water of Lake Nasser

    Directory of Open Access Journals (Sweden)

    Khamis Mansour

    2018-06-01

    Full Text Available The role of the fracture system is important for enhancing the recharge or discharge of fluids in the subsurface reservoir. The Lake Nasser is consider one of the largest artificial lakes all over the world and contains huge bulk of storage water. In this study, the influence of fracture zones on subsurface fluid flow in groundwater reservoirs is investigated using geophysical techniques including seismicity, geoelectric and gravity data. These data have been utilized for exploring structural structure in south west Lake Nasser, and subsurface discontinuities (joints or faults notwithstanding its related fracture systems. Seismicity investigation gave us the comprehension of the dynamic geological structure sets and proposing the main recharging paths for the Nubian aquifer from Lake Nasser surface water. Processing and modelling of aerogravity data show that the greater thickness of sedimentary cover (700 m is located eastward and northward while basement outcrops occur at Umm Shaghir and Al Asr areas. Sixty-nine vertical electrical soundings (VES’s were used to delineate the subsurface geoelectric layers along eight profiles that help to realize the subsurface geological structure behind the hydrogeological conditions of the studied area. Keywords: Fracture system, Seismicity, Groundwater reservoir, Gravity, VES

  11. Trajectory of social isolation following hip fracture: an analysis of the English Longitudinal Study of Ageing (ELSA) cohort.

    Science.gov (United States)

    Smith, Toby O; Dainty, Jack R; MacGregor, Alex

    2018-01-01

    social isolation is defined as a lack of meaningful and sustained communication or interactions with social networks. There is limited understanding on the prevalence of social isolation and loneliness in people following hip fracture and no previous understanding of how this changes over time. to determine the prevalence and trajectory of social isolation and loneliness before a hip fracture, during the recovery phase and a minimum of 2 years post-hip fracture in an English population. data were from the English Longitudinal Study of Ageing (ELSA) cohort (2004/5-2014/15). The sample comprised of 215 participants who had sustained a hip fracture. Measures of social isolation and loneliness were analysed through multilevel modelling to determine their trajectories during three-time intervals (pre-fracture; interval at hip fracture and recovery; minimum 2 years post-fracture). The prevalence of social isolation and loneliness were determined pre- and post-fracture. prevalence of social isolation was 19% post-hip fracture and loneliness 13% post-hip fracture. There was no statistically significant change in social isolation pre-fracture compared to a minimum of 2 years post-fracture (P = 0.78). Similarly, there was no statistically significant change in loneliness pre-fracture compared to a minimum of 2 years post-fracture (P = 0.12). this analysis has determined that whilst social isolation and loneliness do not change over time following hip fracture, these remain a significant problem for this population. Interventions are required to address these physical and psychological health needs. This is important as they may have short and longer term health benefits for people post-hip fracture. © The Author 2017. Published by Oxford University Press on behalf of the British Geriatrics Society.All rights reserved. For permissions, please email: journals.permissions@oup.com

  12. Summary of micrographic analysis of fracture coating phases on drill cores from Pahute Mesa, Nevada Test Site. Revision 1

    International Nuclear Information System (INIS)

    1998-12-01

    The flow path between Pahute Mesa and the groundwater discharge area in Oasis Valley (approximately 18 miles to the southwest) is of concern due to the relatively short travel distance between a recharge area where underground nuclear testing has been conducted and the off-site water users. Groundwater flow and transport modeling by IT Corporation (IT) has shown rapid tritium transport in the volcanic rock aquifers along this flow path. The resultant estimates of rapid transport were based on water level data, limited hydraulic conductivity data, estimates of groundwater discharge rates in Oasis Valley, assumed porosities, and estimated retardation rates. Many of these parameters are poorly constrained and may vary considerably. Sampling and analytical techniques are being applied as an independent means to determine transport rates by providing an understanding of the geochemical processes that control solute movement along the flow path. As part of these geochemical investigations, this report summarizes the analysis of fracture coating mineral phases from drill core samples from the Pahute mesa area of the Nevada Test Site (NTS). Archived samples were collected based on the presence of natural fractures and on the types and abundance of secondary mineral phases present on those fracture surfaces. Mineral phases present along fracture surfaces are significant because, through the process of water-rock interaction, they can either contribute (as a result of dissolution) or remove (as a result of precipitation or adsorption) constituents from solution. Particular attention was paid to secondary calcite occurrences because they represent a potential source of exchangeable carbon and can interact with groundwater resulting in a modified isotopic signature and apparent water age

  13. Histomorphometrical analysis on the effects of two therapeutic ultrasound intensities on fracture healing in aged rats

    Directory of Open Access Journals (Sweden)

    Jeronimo Rafael Skau

    Full Text Available Introduction Experimental studies conducted in young animals show that therapeutic ultrasound (TUS has been successfully used to shorten the healing time of bone fractures. However, they were not found in the literature, studies comparing the effect of different intensities of UST in aged animals. Objective To test the efficacy of intensity 1.0 W/cm2 and of 0.5 W/cm2 in the consolidation of experimental fracture of the tibia from aged Wistar rats. Materials and methods Three groups of 15 month old rats were submitted to a midshaft osteotomy of the tibia and then, the hind member was immobilized with a metal splint and plaster of Paris, wrapping the knee and ankle joint. One group (L, received ultrasound at 0.5 W/cm2; the other group (I, were exposed to ultrasound at 1.0 W/cm2. One control group (C, did not receive the ultrasound. Fifteen animals (five from each group were euthanatized at the end of the first week and fifteen (five from each group at the end of the third week. The progress of the fracture healing was performed for each group by morphometric analysis of histological sections of the fracture region. Results and conclusion The results showed that fractures treated with ultrasound at 1.0 W/cm2 healed significantly faster than did the fractures treated with ultrasound at 0.5 W/cm2 and the control.

  14. Electrical resistivity dynamics beneath a fractured sedimentary bedrock riverbed in response to temperature and groundwater–surface water exchange

    Directory of Open Access Journals (Sweden)

    C. M. Steelman

    2017-06-01

    Full Text Available Bedrock rivers occur where surface water flows along an exposed rock surface. Fractured sedimentary bedrock can exhibit variable groundwater residence times, anisotropic flow paths, and heterogeneity, along with diffusive exchange between fractures and rock matrix. These properties of the rock will affect thermal transients in the riverbed and groundwater–surface water exchange. In this study, surface electrical methods were used as a non-invasive technique to assess the scale and temporal variability of riverbed temperature and groundwater–surface water interaction beneath a sedimentary bedrock riverbed. Conditions were monitored at a semi-daily to semi-weekly interval over a full annual period that included a seasonal freeze–thaw cycle. Surface electromagnetic induction (EMI and electrical resistivity tomography (ERT methods captured conditions beneath the riverbed along a pool–riffle sequence of the Eramosa River in Canada. Geophysical datasets were accompanied by continuous measurements of aqueous specific conductance, temperature, and river stage. Time-lapse vertical temperature trolling within a lined borehole adjacent to the river revealed active groundwater flow zones along fracture networks within the upper 10 m of rock. EMI measurements collected during cooler high-flow and warmer low-flow periods identified a spatiotemporal riverbed response that was largely dependent upon riverbed morphology and seasonal groundwater temperature. Time-lapse ERT profiles across the pool and riffle sequence identified seasonal transients within the upper 2 and 3 m of rock, respectively, with spatial variations controlled by riverbed morphology (pool versus riffle and dominant surficial rock properties (competent versus weathered rock rubble surface. While the pool and riffle both exhibited a dynamic resistivity through seasonal cooling and warming cycles, conditions beneath the pool were more variable, largely due to the formation of river

  15. Analysis of two different surgical approaches for fractures of the mandibular condyle.

    Science.gov (United States)

    Kumaran, S; Thambiah, L J

    2012-01-01

    Fractures of the condyle account for one third of all the mandibular fractures. Different surgical approaches to the condyle described hitherto testify to the advantages and disadvantages of the different surgical techniques used for approaching the condyle in such cases of fractures. We have described and compared two of such surgical techniques in this study. The aim of this study is to compare the outcome of dealing with condylar fractures by two different surgical techniques: the mini retromandibular approach, and the preauricular approach. A prospective study of 31 patients who had suffered with mandibular condylar fractures was carried out. Of these, 26 patients had unilateral condylar fractures, and 5 patients had a bilateral fracture. Further, 19 of these patients were treated by the mini retromandibular approach and 12 by the preauricular approach. The treated patients were followed up and evaluated for a minimum period of 1 year and assessed for parameters such as the maximum mouth opening, lateral movement on the fractured side, mandibular movements such as protrusion, dental occlusion, scar formation, facial nerve weakness, salivary fistula formation and time taken for the completion of the surgical procedure. t- test was used for statistical analysis of the data obtained in the study. Dental occlusion was restored in all the cases, and good anatomical reduction was achieved. The mean operating time was higher 63.53 (mean) ± 18.12 minutes standard deviation (SD) in the preauricular approach compared to 45.22 (mean) ± 18.86 minutes SD in the mini retromandibular approach. Scar formation was satisfactory in almost all the cases.

  16. Evaluation of fracture behavior of SA-516 steel welds using acoustic emission analysis

    International Nuclear Information System (INIS)

    Na, Eui Gyun; Ono, Kanji; Lee, Dong Whan

    2006-01-01

    The purpose of this study is to evaluate the AE characteristics for the basemetal, PWHT (Post-Weld Heat Treatment) and weldment specimens of SA-516 steel during fracture testing. Four-point bending and AE tests were conducted simultaneously. AE signals were emitted in the process of plastic deformation. AE signal strength and amplitude of the weldment was the strongest, followed by PWHT specimen and basemetal. More AE signals were emitted from the weldment samples because of the oxides, and discontinuous mechanical properties. AE signal strength and amplitude for the basemetal or PWHT specimen decreased remarkably compared to the weldment because of lower strength. Pre-cracked specimens emitted even lower event counts than the corresponding blunt notched specimens. Dimple fracture from void coalescence mechanism is associated with low-level AE signal strength for the basemetal or PWHT. Tearing mode and dimple formation were shown on the fracture surfaces of the weldment, but only a small fraction produced detectable AE

  17. Thyroid Function Tests in the Reference Range and Fracture: Individual Participant Analysis of Prospective Cohorts.

    Science.gov (United States)

    Aubert, Carole E; Floriani, Carmen; Bauer, Douglas C; da Costa, Bruno R; Segna, Daniel; Blum, Manuel R; Collet, Tinh-Hai; Fink, Howard A; Cappola, Anne R; Syrogiannouli, Lamprini; Peeters, Robin P; Åsvold, Bjørn O; den Elzen, Wendy P J; Luben, Robert N; Bremner, Alexandra P; Gogakos, Apostolos; Eastell, Richard; Kearney, Patricia M; Hoff, Mari; Le Blanc, Erin; Ceresini, Graziano; Rivadeneira, Fernando; Uitterlinden, André G; Khaw, Kay-Tee; Langhammer, Arnulf; Stott, David J; Westendorp, Rudi G J; Ferrucci, Luigi; Williams, Graham R; Gussekloo, Jacobijn; Walsh, John P; Aujesky, Drahomir; Rodondi, Nicolas

    2017-08-01

    Hyperthyroidism is associated with increased fracture risk, but it is not clear if lower thyroid-stimulating hormone (TSH) and higher free thyroxine (FT4) in euthyroid individuals are associated with fracture risk. To evaluate the association of TSH and FT4 with incident fractures in euthyroid individuals. Individual participant data analysis. Thirteen prospective cohort studies with baseline examinations between 1981 and 2002. Adults with baseline TSH 0.45 to 4.49 mIU/L. Primary outcome was incident hip fracture. Secondary outcomes were any, nonvertebral, and vertebral fractures. Results were presented as hazard ratios (HRs) with 95% confidence interval (CI) adjusted for age and sex. For clinical relevance, we studied TSH according to five categories: 0.45 to 0.99 mIU/L; 1.00 to 1.49 mIU/L; 1.50 to 2.49 mIU/L; 2.50 to 3.49 mIU/L; and 3.50 to 4.49 mIU/L (reference). FT4 was assessed as study-specific standard deviation increase, because assays varied between cohorts. During 659,059 person-years, 2,565 out of 56,835 participants had hip fracture (4.5%; 12 studies with data on hip fracture). The pooled adjusted HR (95% CI) for hip fracture was 1.25 (1.05 to 1.49) for TSH 0.45 to 0.99 mIU/L, 1.19 (1.01 to 1.41) for TSH 1.00 to 1.49 mIU/L, 1.09 (0.93 to 1.28) for TSH 1.50 to 2.49 mIU/L, and 1.12 (0.94 to 1.33) for TSH 2.50 to 3.49 mIU/L (P for trend = 0.004). Hip fracture was also associated with FT4 [HR (95% CI) 1.22 (1.11 to 1.35) per one standard deviation increase in FT4]. FT4 only was associated with any and nonvertebral fractures. Results remained similar in sensitivity analyses. Among euthyroid adults, lower TSH and higher FT4 are associated with an increased risk of hip fracture. These findings may help refine the definition of optimal ranges of thyroid function tests. Copyright © 2017 Endocrine Society

  18. Analysis of radionuclide transport through fracture networks by percolation theory

    International Nuclear Information System (INIS)

    Ahn, Joonhong; Furuhama, Yutaka; Li, Yadong; Suzuki, Atsuyuki

    1991-01-01

    Presented are results of numerical simulations for radionuclide diffusion through fracture networks in geologic layers. Actual fracture networks are expressed as two-dimensional honeycomb percolation lattices. Random-walk simulations of diffusion on percolation lattices are made by the exact-enumeration method, and compared with those from Fickian diffusion with constant and decreasing diffusion coefficients. Mean-square displacement of a random-walker on percolation lattices increases more slowly with time than that for Fickian diffusion with the constant diffusion coefficient. Though the same relation of mean-square displacement vs. time as for the percolation lattices can be obtained for a continuum with decreasing diffusion coefficients, spatial distribution of probability densities of finding the random-walker on the percolation lattice differs from that on a continuum with the decreasing diffusion coefficient. The percolation model results in slow spreading near the origin and fast spreading in the outer region, whereas the decreasing-diffusion coefficient model shows the reverse because of smaller diffusion coefficient in the outer region. We could derive a general formula that can include both Fickian and anomalous diffusion in terms of fractal and fracton dimensionalities and the anomalous diffusion exponent. (author)

  19. Elastoplasticity analysis of the nails used in long bone fractures

    International Nuclear Information System (INIS)

    Paterson, R; Paterson, A; Miralles, M T; Del Sel, G; Del Sel, N

    2011-01-01

    Elastoplastic endomedullary nail-insertion system in long bone fractures is a method which allows generating forces, moments, frictions and stress states in parts of the bone previously selected. Adding previous knowledge on the distribution of forces and acting moments over the bone fragments to be threaded, as well as on the elastoplastic and mechanical properties of the nails to be inserted (designing a special, specific structure for each case), the results, coming from 26 years of applying this technique, have been promising. It is from this perspective that we call this threading and anchoring procedure 'Selective Tension System' (STS). Physicochemical analyses and mechanical trials on elastoplastic nails used in the osteosynthesis in long bone fractures are presented. The magnitude of the forces produced by flattening the nails and the reacting forces at both ends are measured. It is expected that the evidence provided on the elastic variability of these nails will be useful as guidance on the availability and choice of the elastoplastic combinations that best fit each patient.

  20. J-integral evaluation and stability analysis in the unstable ductile fracture

    International Nuclear Information System (INIS)

    Miyoshi, Toshiro; Yoshida, Yuichiro; Shiratori, Masaki.

    1984-01-01

    Concerning unstable ductile fracture, which is an important problem on the structural stability of line pipes, nuclear reactor piping and so on, the research on fracture mechanics parameters which control the beginning of the stable growth and unstable growth of cracks attracts interest. At present, as the parameters, the T-modulus based on J-integral crack tip opening angle, crack opening angle averaged over crack developing part, plastic work coefficient and so on have been proposed. The research on the effectiveness and inter-relation of these parameters is divided into generation phase and application phase, and by these researches, it was reported that all T-modulus, CTOA and COA took almost constant values in relation to crack development, except initial transition period. In order to decide which parameter is most appropriate, the detailed analysis is required. In this study, the analysis of unstable ductile fracture of a central crack test piece and a small tensile test piece was carried out by finite element method, and the evaluation of J-integral in relation to crack development, J-integral resistance value when COA is assumed to be a constant, the form of an unstable fracture occurring point and the compliance dependence were examined. The method of analysis, the evaluation of J-integral, J-integral resistance value, unstable fracture occurring point and stability diagram are described. (Kako, I.)

  1. A description of the BNL active surface analysis facility

    International Nuclear Information System (INIS)

    Tyler, J.W.

    1989-11-01

    Berkeley Nuclear Laboratories has a responsibility for the assessment of radioactive specimens arising both from post irradiation examination of power reactor components and structures and experimental programmes concerned with fission and activation product transport. Existing analytical facilities have been extended with the commissioning of an active surface analysis instrument (XSAM 800pci, Kratos Analytical). Surface analysis involves the characterisation of the outer few atomic layers of a solid surface/interface whose chemical composition and electronic structure will probably be different from the bulk. The new instrument consists three interconnected chambers positioned in series; comprising of a high vacuum sample introduction chamber, an ultra-high vacuum sample treatment/fracture chamber and an ultra-high vacuum sample analysis chamber. The sample analysis chamber contains the electron, X-ray and ion-guns and the electron and ion detectors necessary for performing X-ray photoelectron spectroscopy, scanning Auger microscopy and secondary-ion mass spectroscopy. The chamber also contains a high stability manipulator to enable sub-micron imaging of specimens to be achieved and provide sample heating and cooling between - 180 and 600 0 C. (author)

  2. Ion implantation and fracture toughness of ceramics

    International Nuclear Information System (INIS)

    Clark, J.; Pollock, J.T.A.

    1985-01-01

    Ceramics generally lack toughness which is largely determined by the ceramic surface where stresses likely to cause failure are usually highest. Ion implantation has the capacity to improve the surface fracture toughness of ceramics. Significantly reduced ion size and reactivity restrictions exist compared with traditional methods of surface toughening. We are studying the effect of ion implantation on ceramic fracture toughness using indentation testing as the principal tool of analysis

  3. Intraarticular calcaneal fractures. Clinical results and functional analysis of the surgical treatment

    International Nuclear Information System (INIS)

    Calixto B, Luis Fernando; Gomez R, Jairo Fernando; Prieto S, Hernan Augusto

    2004-01-01

    This study evaluated the clinical and functional outcome of open reduction and internal fixation in intraarticular calcaneal fractures 22 patients with 24 intra-articular fractures of calcaneous were treated, 19 with open reduction and internal fixation using a 3.5 mm AO/ASIF calcaneal plate. The fractures were classified according the Sanders tomographic system. The Bohler angle was measured before and after the surgery. All patients were evaluated using the functional ankle-hind foot AOFAS scale (American Orthopaedics Foot and Ankle Society) 6 and 12 months after the surgery. Mean age was 39.8 years. The distribution according the type of fracture was: Sanders II: 41.67% and Sanders III: 58.33%. The mean value of the initial Bohler angle was 11.45% and the final was 24.5 degrees. The functional outcome after 6 months was 70 points and after 12 months was 82 points. There were only two complications (12.5%) a fistula and a wound dehiscence. The displaced and slightly comminuted intra articular fractures have the calcaneus (Sandres II and Sandres III) benefit of ORIF obtaining good functional outcomes 6 and 12 months after surgery. This procedure allows a better articular surface reduction, a satisfactory Bohler angle correction and earlier rehabilitation

  4. User's manual and analysis methodology of probabilistic fracture mechanics analysis code PASCAL Ver.2 for reactor pressure vessel (Contract research)

    International Nuclear Information System (INIS)

    Osakabe, Kazuya; Onizawa, Kunio; Shibata, Katsuyuki; Kato, Daisuke

    2006-09-01

    As a part of the aging structural integrity research for LWR components, the probabilistic fracture mechanics (PFM) analysis code PASCAL (PFM Analysis of Structural Components in Aging LWR) has been developed in JAEA. This code evaluates the conditional probabilities of crack initiation and fracture of a reactor pressure vessel (RPV) under transient conditions such as pressurized thermal shock (PTS). The development of the code has been aimed to improve the accuracy and reliability of analysis by introducing new analysis methodologies and algorithms considering the recent development in the fracture mechanics and computer performance. PASCAL Ver.1 has functions of optimized sampling in the stratified Monte Carlo simulation, elastic-plastic fracture criterion of the R6 method, crack growth analysis models for a semi-elliptical crack, recovery of fracture toughness due to thermal annealing and so on. Since then, under the contract between the Ministry of Economy, Trading and Industry of Japan and JAEA, we have continued to develop and introduce new functions into PASCAL Ver.2 such as the evaluation method for an embedded crack, K I database for a semi-elliptical crack considering stress discontinuity at the base/cladding interface, PTS transient database, and others. A generalized analysis method is proposed on the basis of the development of PASCAL Ver.2 and results of sensitivity analyses. Graphical user interface (GUI) including a generalized method as default values has been also developed for PASCAL Ver.2. This report provides the user's manual and theoretical background of PASCAL Ver.2. (author)

  5. A retrospective, semi-quantitative image quality analysis of cone beam computed tomography (CBCT) and MSCT in the diagnosis of distal radius fractures

    International Nuclear Information System (INIS)

    Lang, H.; Neubauer, J.; Fritz, B.; Spira, E.M.; Strube, J.; Langer, M.; Kotter, E.

    2016-01-01

    To compare image quality and diagnostic validity of CBCT and MSCT for distal radius fractures. 35 CBCT and 33 MSCT scans were retrospectively reviewed with a visual grading scale regarding the depiction of cortical bone, trabecular bone, articular surfaces, and soft tissue. The extent and type of artefacts was analyzed. Agreement on AO classification and measurement of cortical disruption and length of the fracture gap was determined. Fracture reduction was evaluated in post-treatment x-rays. Statistical analysis was performed with visual grading characteristics (VGC), chi square tests, and Kendall's coefficient of concordance. CBCT performed significantly worse for cortical bone, articular surfaces, and especially soft tissue. Trabecular bone showed no significant difference. Significantly more CBCT images showed artefacts. Physics-based artefacts were the most common. CBCT scans also showed motion artefacts. There was no significant difference in agreement on AO classification. The agreement on measurements was substantial for both modalities. Slightly more fractures that had undergone MSCT imaging showed adequate reduction. This initial study of an orthopaedic extremity CBCT scanner showed that the image quality of a CBCT scanner remains inferior for most structures at standard settings. Diagnostic validity of both modalities for distal radius fractures seems similar. (orig.)

  6. A retrospective, semi-quantitative image quality analysis of cone beam computed tomography (CBCT) and MSCT in the diagnosis of distal radius fractures

    Energy Technology Data Exchange (ETDEWEB)

    Lang, H.; Neubauer, J.; Fritz, B.; Spira, E.M.; Strube, J.; Langer, M.; Kotter, E. [University Medical Center Freiburg, Department of Radiology, Freiburg (Germany)

    2016-12-15

    To compare image quality and diagnostic validity of CBCT and MSCT for distal radius fractures. 35 CBCT and 33 MSCT scans were retrospectively reviewed with a visual grading scale regarding the depiction of cortical bone, trabecular bone, articular surfaces, and soft tissue. The extent and type of artefacts was analyzed. Agreement on AO classification and measurement of cortical disruption and length of the fracture gap was determined. Fracture reduction was evaluated in post-treatment x-rays. Statistical analysis was performed with visual grading characteristics (VGC), chi square tests, and Kendall's coefficient of concordance. CBCT performed significantly worse for cortical bone, articular surfaces, and especially soft tissue. Trabecular bone showed no significant difference. Significantly more CBCT images showed artefacts. Physics-based artefacts were the most common. CBCT scans also showed motion artefacts. There was no significant difference in agreement on AO classification. The agreement on measurements was substantial for both modalities. Slightly more fractures that had undergone MSCT imaging showed adequate reduction. This initial study of an orthopaedic extremity CBCT scanner showed that the image quality of a CBCT scanner remains inferior for most structures at standard settings. Diagnostic validity of both modalities for distal radius fractures seems similar. (orig.)

  7. Structural analysis of a fractured basement reservoir, central Yemen

    Science.gov (United States)

    Veeningen, Resi; Rice, Hugh; Schneider, Dave; Grasemann, Bernhard; Decker, Kurt

    2013-04-01

    The Pan-African Arabian-Nubian Shield (ANS), within which Yemen lies, formed as a result of Neoproterozoic collisional events between c. 870-550 Ma. Several subsequent phases of extension occurred, from the Mesozoic (due to the breakup of Gondwana) to the Recent (forming the Gulf of Aden and the Red Sea). These resulted in the formation of numerous horst- and-graben structures and the development of fractured basement reservoirs in the southeast part of the ANS. Two drill cores from the Mesozoic Marib-Shabwa Basin, central Yemen, penetrated the upper part of the Pan-African basement. The cores show both a lithological and structural inhomogeneity, with variations in extension-related deformation structures such as dilatational breccias, open fractures and closed veins. At least three deformation events have been recognized: D1) Ductile to brittle NW-SE directed faulting during cooling of a granitic pluton. U-Pb zircon ages revealed an upper age limit for granite emplacement at 627±3.5 Ma. As these structures show evidence for ductile deformation, this event must have occurred during the Ediacaran, shortly after intrusion, since Rb/Sr and (U-Th)/He analyses show that subsequent re-heating of the basement did not take place. D2) The development of shallow dipping, NNE-SSW striking extensional faults that formed during the Upper Jurassic, simultaneously with the formation of the Marib-Shabwa Basin. These fractures are regularly cross-cut by D3. D3) Steeply dipping NNE-SSW to ENE-WSW veins that are consistent with the orientation of the opening of the Gulf of Aden. These faults are the youngest structures recognized. The formation of ductile to brittle faults in the granite (D1) resulted in a hydrothermally altered zone ca. 30 cm wide replacing (mainly) plagioclase with predominantly chlorite, as well as kaolinite and heavy element minerals such as pyrite. The alteration- induced porosity has an average value of 20%, indicating that the altered zone is potentially a

  8. Essential work of fracture analysis for starch filled poly(propylene carbonate) composites

    International Nuclear Information System (INIS)

    Wang, X.L.; Li, R.K.Y.; Cao, Y.X.; Meng, Y.Z.

    2007-01-01

    Starch filled poly(propylene carbonate) composites are environmental friendly materials. In this study, the fracture toughness of composites under mode I loading was determined by the essential work of fracture concept. The specific essential fracture work of the poly(propylene carbonate)/starch composites decreases with increasing the starch content, while the non-essential work term, βw p increases with increasing the starch content. In addition, the morphologies, thermal properties, thermo-mechanical properties were studied by scanning electron microscope, thermogravimetric analysis, dynamic mechanical analysis, and differential scanning calorimetry, respectively. The thermal and thermo-mechanical measurements revealed that increasing starch content led to an increase in glass transition temperature and thermal stability. Morphology observation indicates that poly(propylene carbonate) and starch have weak interfacial adhesion

  9. Outcome analysis of retrograde nailing and less invasive stabilization system in distal femoral fractures: A retrospective analysis

    Directory of Open Access Journals (Sweden)

    Christian Hierholzer

    2011-01-01

    . Accumulative result of functional outcome using the Knee and Osteoarthritis Outcome (KOOS score demonstrated in type A fractures a score of 263 (RN and 260 (LISS, and in type C fractures 257 (RN and 218 (LISS. Differences between groups for type A were statistically insignificant, statistical analysis for type C fractures between the two groups are not possible, since in type C2 and C3 fractures only LISS plating was performed. Conclusion: Both retrograde IM nailing and angular stable plating are adequate treatment options for distal femur fractures. Locked plating can be used for all distal femur fractures including complex type C fractures, periprosthetic fractures, as well as osteoporotic fractures. IM nailing provides favorable stability and can be successfully implanted in bilateral or multisegmental fractures of the lower extremity as well as in extra-articular fractures. However, both systems require precise preoperative planning and advanced surgical experience to reduce the risk of revision surgery. Clinical outcome largely depends on surgical technique rather than on the choice of implant.

  10. Uncertainty analysis for probabilistic pipe fracture evaluations in LBB applications

    International Nuclear Information System (INIS)

    Rahman, S.; Ghadiali, N.; Wilkowski, G.

    1997-01-01

    During the NRC's Short Cracks in Piping and Piping Welds Program at Battelle, a probabilistic methodology was developed to conduct fracture evaluations of circumferentially cracked pipes for application to leak-rate detection. Later, in the IPIRG-2 program, several parameters that may affect leak-before-break and other pipe flaw evaluations were identified. This paper presents new results from several uncertainty analyses to evaluate the effects of normal operating stresses, normal plus safe-shutdown earthquake stresses, off-centered cracks, restraint of pressure-induced bending, and dynamic and cyclic loading rates on the conditional failure probability of pipes. systems in BWR and PWR. For each parameter, the sensitivity to conditional probability of failure and hence, its importance on probabilistic leak-before-break evaluations were determined

  11. Uncertainty analysis for probabilistic pipe fracture evaluations in LBB applications

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, S.; Ghadiali, N.; Wilkowski, G.

    1997-04-01

    During the NRC`s Short Cracks in Piping and Piping Welds Program at Battelle, a probabilistic methodology was developed to conduct fracture evaluations of circumferentially cracked pipes for application to leak-rate detection. Later, in the IPIRG-2 program, several parameters that may affect leak-before-break and other pipe flaw evaluations were identified. This paper presents new results from several uncertainty analyses to evaluate the effects of normal operating stresses, normal plus safe-shutdown earthquake stresses, off-centered cracks, restraint of pressure-induced bending, and dynamic and cyclic loading rates on the conditional failure probability of pipes. systems in BWR and PWR. For each parameter, the sensitivity to conditional probability of failure and hence, its importance on probabilistic leak-before-break evaluations were determined.

  12. First spinning cylinder test analysis by using local approach to fracture

    International Nuclear Information System (INIS)

    Eripret, C.; Rousselier, G.

    1993-01-01

    In recent years, several experimental programs on large scale specimens were organized to evaluate capabilities of the fracture mechanics concepts employed in structural integrity assessment of PWR pressure vessels. During the first spinning cylinder test, a geometry effect was experimentally pointed out and exhibited the problem of transferability of toughness data from small scale to large scale specimens. An original analysis of this test, by means of local approach to fracture is presented in this paper. Both compact tension specimen and spinning cylinder fracture behaviour were computed by using a continuum damage mechanics model developed at EDF. The authors confirmed by numerical analysis that the cylinder's resistance to ductile tearing was considerably larger than in small scale fracture mechanics specimens tests, about 50 percent. The final crack growth predicted by the model was close to the experimental value. Discrepancies in J-R curves seemed to be due to an effect of stress triaxiality and plastic zone evolution. The geometry effect inducing differences in resistance to ductile tearing of the material involved in the specimens can be investigated and explained by using local approach to fracture methodology. 14 refs., 9 figs., 2 tabs

  13. Spall formation in solution mined storage caverns based on a creep and fracture analysis

    International Nuclear Information System (INIS)

    Munson, Darrell E.

    2000-01-01

    Because of limited direct observation, understanding of the interior conditions of the massive storage caverns constructed in Gulf Coast salt domes is realizable only through predictions of salt response. Determination of the potential for formation of salt spans, leading to eventual salt falls, is based on salt creep and fracture using the Multimechanism-Deformation Coupled Fracture (MCDF) model. This is a continuum model for creep, coupled to continuum damage evolution. The model has been successfully tested against underground results of damage around several test rooms at the Waste Isolation Pilot Plant (WIPP). Model simulations, here, evaluate observations made in the Strategic Petroleum Reserve (SPR) storage caverns, namely, the accumulation of material on cavern floors and evidence of salt falls. A simulation of a smooth cavern wall indicates damage is maximum at the surface but diminishes monotonically into the salt, which suggests the source of salt accumulation is surface sluffing. If a protuberance occurs on the wall, fracture damage can form beneath the protuberance, which will eventually cause fracture, and lead to a salt fall

  14. A multicomponent tracer field experiment to measure the flow volume, surface area, and rectilinear spacing of fractures away from the wellbore

    Science.gov (United States)

    Cathles, L. M.; Sanford, W. E.; Hawkins, A.; Li, Y. V.

    2017-12-01

    The nature of flow in fractured porous media is important to almost all subsurface processes including oil and gas recovery, contaminant transport and remediation, CO2 sequestration, and geothermal heat extraction. One would like to know, under flowing conditions, the flow volume, surface area, effective aperture, and rectilinear spacing of fractures in a representative volume of rock away from the well bore, but no methods currently allow acquisition of this data. It could, however, be collected by deploying inert tracers with a wide range of aqueous diffusion constants (e.g., rapidly diffusing heat to non-diffusing nanoparticle) in the following fashion: The flow volume is defined by the heated volume measured by resistivity surveys. The fracture volume within this flow volume is indicate by the nanoparticle transit time. The average fracture spacing is indicated by the evolving thermal profile in the monitor and the production wells (measured by fiber optic cable), and by the retention of absorbing tracers. The average fracture aperture is determined by permeability measurements and the average fracture separation. We have proposed a field test to redundantly measure these fracture parameters in the fractured Dakota Sandstone where it approaches the surface in Ft Collins, Colorado. Five 30 m deep wells (an injection, production, and 3 monitor wells) cased to 20 m are proposed. The experiments will involve at least 9 different tracers. The planned field test and its potential significance will be described.

  15. Surface computing and collaborative analysis work

    CERN Document Server

    Brown, Judith; Gossage, Stevenson; Hack, Chris

    2013-01-01

    Large surface computing devices (wall-mounted or tabletop) with touch interfaces and their application to collaborative data analysis, an increasingly important and prevalent activity, is the primary topic of this book. Our goals are to outline the fundamentals of surface computing (a still maturing technology), review relevant work on collaborative data analysis, describe frameworks for understanding collaborative processes, and provide a better understanding of the opportunities for research and development. We describe surfaces as display technologies with which people can interact directly, and emphasize how interaction design changes when designing for large surfaces. We review efforts to use large displays, surfaces or mixed display environments to enable collaborative analytic activity. Collaborative analysis is important in many domains, but to provide concrete examples and a specific focus, we frequently consider analysis work in the security domain, and in particular the challenges security personne...

  16. Assessment of Surface Water Contamination from Coalbed Methane Fracturing-Derived Volatile Contaminants in Sullivan County, Indiana, USA.

    Science.gov (United States)

    Meszaros, Nicholas; Subedi, Bikram; Stamets, Tristan; Shifa, Naima

    2017-09-01

    There is a growing concern over the contamination of surface water and the associated environmental and public health consequences from the recent proliferation of hydraulic fracturing in the USA. Petroleum hydrocarbon-derived contaminants of concern [benzene, toluene, ethylbenzene, and xylenes (BTEX)] and various dissolved cations and anions were spatially determined in surface waters around 15 coalbed methane fracking wells in Sullivan County, IN, USA. At least one BTEX compound was detected in 69% of sampling sites (n = 13) and 23% of sampling sites were found to be contaminated with all of the BTEX compounds. Toluene was the most common BTEX compound detected across all sampling sites, both upstream and downstream from coalbed methane fracking wells. The average concentration of toluene at a reservoir and its outlet nearby the fracking wells was ~2× higher than other downstream sites. However, one of the upstream sites was found to be contaminated with BTEX at similar concentrations as in a reservoir site nearby the fracking well. Calcium (~60 ppm) and sulfates (~175 ppm) were the dominant cations and anions, respectively, in surface water around the fracking sites. This study represents the first report of BTEX contamination in surface water from coalbed methane hydraulic fracturing wells.

  17. Dairy product consumption and risk of hip fracture: a systematic review and meta-analysis.

    Science.gov (United States)

    Bian, Shanshan; Hu, Jingmin; Zhang, Kai; Wang, Yunguo; Yu, Miaohui; Ma, Jie

    2018-01-22

    Dairy product consumption may affect the risk of hip fracture, but previous studies have reported inconsistent findings. The primary aim of our meta-analysis was to examine and quantify the potential association of dairy product consumption with risk of hip fracture. We searched the databases of PubMed and EMBASE for relevant articles from their inception through April 17, 2017. The final analysis included 10 cohort studies and 8 case-control studies. Random-effects models were used to estimate the pooled risk. Subgroup and dose-response analyses were conducted to explore the relationships between the consumption of milk and the risk of hip fracture. After pooling the data from the included studies, the summary relative risk (RR) for hip fracture for highest versus lowest consumption were 0.91 (95% CI: 0.74-1.12), 0.75 (95% CI: 0.66-0.86), 0.68 (95% CI: 0.61-0. 77), 1.02 (95% CI: 0.93-1.12) for milk, yogurt, cheese, and total dairy products in cohort studies, respectively. Higher milk consumption [Odds ratio (OR), 0.71, 95% CI: 0.55-0. 91] was associated with lower risk of hip fracture for highest versus lowest consumption in case-control studies. After quantifying the specific dose of milk, the summary RR/OR for an increased milk consumption of 200 g/day was 1.00 (95% CI: 0.94-1.07), and 0.89 (95%CI: 0.64-1.24) with significant heterogeneity for cohort and case-control studies, respectively; There was a nonlinear association between milk consumption and hip fracture risk in cohort, and case-control studies. Our findings indicate that consumption of yogurt and cheese was associated with lower risk of hip fracture in cohort studies. However, the consumption of total dairy products and cream was not significantly associated with the risk of hip fracture. There was insufficient evidence to deduce the association between milk consumption and risk of hip fracture. A lower threshold of 200 g/day milk intake may have beneficial effects, whereas the effects of a higher

  18. A customized fixation plate with novel structure designed by topological optimization for mandibular angle fracture based on finite element analysis.

    Science.gov (United States)

    Liu, Yun-Feng; Fan, Ying-Ying; Jiang, Xian-Feng; Baur, Dale A

    2017-11-15

    The purpose of this study was to design a customized fixation plate for mandibular angle fracture using topological optimization based on the biomechanical properties of the two conventional fixation systems, and compare the results of stress, strain and displacement distributions calculated by finite element analysis (FEA). A three-dimensional (3D) virtual mandible was reconstructed from CT images with a mimic angle fracture and a 1 mm gap between two bone segments, and then a FEA model, including volume mesh with inhomogeneous bone material properties, three loading conditions and constraints (muscles and condyles), was created to design a customized plate using topological optimization method, then the shape of the plate was referenced from the stress concentrated area on an initial part created from thickened bone surface for optimal calculation, and then the plate was formulated as "V" pattern according to dimensions of standard mini-plate finally. To compare the biomechanical behavior of the "V" plate and other conventional mini-plates for angle fracture fixation, two conventional fixation systems were used: type A, one standard mini-plate, and type B, two standard mini-plates, and the stress, strain and displacement distributions within the three fixation systems were compared and discussed. The stress, strain and displacement distributions to the angle fractured mandible with three different fixation modalities were collected, respectively, and the maximum stress for each model emerged at the mandibular ramus or screw holes. Under the same loading conditions, the maximum stress on the customized fixation system decreased 74.3, 75.6 and 70.6% compared to type A, and 34.9, 34.1, and 39.6% compared to type B. All maximum von Mises stresses of mandible were well below the allowable stress of human bone, as well as maximum principal strain. And the displacement diagram of bony segments indicated the effect of treatment with different fixation systems. The

  19. Fracture detection, mapping, and analysis of naturally fractured gas reservoirs using seismic technology. Final report, November 1995

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-10-01

    Many basins in the Rocky Mountains contain naturally fractured gas reservoirs. Production from these reservoirs is controlled primarily by the shape, orientation and concentration of the natural fractures. The detection of gas filled fractures prior to drilling can, therefore, greatly benefit the field development of the reservoirs. The objective of this project was to test and verify specific seismic methods to detect and characterize fractures in a naturally fractured reservoir. The Upper Green River tight gas reservoir in the Uinta Basin, Northeast Utah was chosen for the project as a suitable reservoir to test the seismic technologies. Knowledge of the structural and stratigraphic geologic setting, the fracture azimuths, and estimates of the local in-situ stress field, were used to guide the acquisition and processing of approximately ten miles of nine-component seismic reflection data and a nine-component Vertical Seismic Profile (VSP). Three sources (compressional P-wave, inline shear S-wave, and cross-line, shear S-wave) were each recorded by 3-component (3C) geophones, to yield a nine-component data set. Evidence of fractures from cores, borehole image logs, outcrop studies, and production data, were integrated with the geophysical data to develop an understanding of how the seismic data relate to the fracture network, individual well production, and ultimately the preferred flow direction in the reservoir. The multi-disciplinary approach employed in this project is viewed as essential to the overall reservoir characterization, due to the interdependency of the above factors.

  20. Facial Fractures.

    Science.gov (United States)

    Ghosh, Rajarshi; Gopalkrishnan, Kulandaswamy

    2018-06-01

    The aim of this study is to retrospectively analyze the incidence of facial fractures along with age, gender predilection, etiology, commonest site, associated dental injuries, and any complications of patients operated in Craniofacial Unit of SDM College of Dental Sciences and Hospital. This retrospective study was conducted at the Department of OMFS, SDM College of Dental Sciences, Dharwad from January 2003 to December 2013. Data were recorded for the cause of injury, age and gender distribution, frequency and type of injury, localization and frequency of soft tissue injuries, dentoalveolar trauma, facial bone fractures, complications, concomitant injuries, and different treatment protocols.All the data were analyzed using statistical analysis that is chi-squared test. A total of 1146 patients reported at our unit with facial fractures during these 10 years. Males accounted for a higher frequency of facial fractures (88.8%). Mandible was the commonest bone to be fractured among all the facial bones (71.2%). Maxillary central incisors were the most common teeth to be injured (33.8%) and avulsion was the most common type of injury (44.6%). Commonest postoperative complication was plate infection (11%) leading to plate removal. Other injuries associated with facial fractures were rib fractures, head injuries, upper and lower limb fractures, etc., among these rib fractures were seen most frequently (21.6%). This study was performed to compare the different etiologic factors leading to diverse facial fracture patterns. By statistical analysis of this record the authors come to know about the relationship of facial fractures with gender, age, associated comorbidities, etc.

  1. The initiation and linkage of surface fractures above a buried strike ...

    Indian Academy of Sciences (India)

    a buried strike-slip fault: An experimental approach. N Ghosh and A ... conditions viz., (i) heterogeneous simple shear of the cover rocks above a buried strike slip fault. (wrench .... (iii) study of fracture types in the damage zones from Gozo .... was dominant, the results may vary from a true ... For example, as shown in figure 5 ...

  2. [Calcaneal fractures treated by open reduction and internal fixation with a locking compression plate (LCP). A prospective study. part I: basic analysis of the group].

    Science.gov (United States)

    Svatoš, F; Bartoška, R; Skála-Rosenbaum, J; Douša, P; Pacovský, V; Krbec, M

    2011-01-01

    this was recorded in 38 patients (49.4 %); 18 patients (24.3 %) had a fall from a height below 3 metres. Eight fractures were caused by a fall from the window, seven calcaneal fractures, as part of .polytrauma, were sustained in road accidents (9.1 %) and six calcaneal bones were injured due to ankle sprain in walking on a flat surface (7.8 %). Bilateral fractures occurred in five (6.5 %) patients, the right and left heel bones were injured in 31 (40.3 %) and 41 (53.2 %) fracture cases, respectively. An open fracture was recorded on three occasions (3.7 %). Of the 82 evaluated fractures, 23 were type IIa fractures (28 %) and 59 were type IIb fractures (72 %) according to the Essex-Lopresti classification system. The average injury-surgery interval was 10 days (range, 1 - 23 days). The average operative time was 77 minutes (range, 45-175 min) and the average duration of tourniquet application was 61 minutes (range, 20-130 min). The average length of hospital stay was 18 days (range, 7-61 days). In 15 patients (18.3 % of osteosynthesis cases) wound healing was delayed. Deep wound infection developed in three cases (3.7 %); these required revision surgery which involved implant removal before bone union in two cases and healing of the wound after revision without implant removal in one case. A necrotic lesion in one case (1.2 %) was treated by muscle flap transfer. Complications which varied in type and severity were recorded in 22 % of the patients. The Rowe score was used to evaluate functional outcomes, which were excellent in 44 %, good in 46 %, satisfactory in 4 % and poor in 6 % of the surgically treated patients.. Only about one-third of the patients with calcaneal fractures were indicated for open LCP osteosynthesis. This is in agreement with the strict indication criteria established by the foreign authors with Professors Zwipp and Sanders at the head. It appears that this fracture chiefly occurs in the population of young active men (Kočiš reported only men

  3. Sensitivity analysis of hydraulic fracturing Using an extended finite element method for the PKN model

    NARCIS (Netherlands)

    Garikapati, Hasini; Verhoosel, Clemens V.; van Brummelen, Harald; Diez, Pedro; Papadrakakis, M.; Papadopoulos, V.; Stefanou, G.; Plevris, V.

    2016-01-01

    Hydraulic fracturing is a process that is surrounded by uncertainty, as available data on e.g. rock formations is scant and available models are still rudimentary. In this contribution sensitivity analysis is carried out as first step in studying the uncertainties in the model. This is done to

  4. Preliminary fracture analysis of the core pressure boundary tube for the Advanced Neutron Source Research Reactor

    International Nuclear Information System (INIS)

    Schulz, K.C.

    1995-08-01

    The outer core pressure boundary tube (CPBT) of the Advanced neutron Source (ANS) reactor being designed at Oak Ridge National Laboratory is currently specified as being composed of 6061-T6 aluminum. ASME Boiler and Pressure Vessel Code fracture analysis rules for nuclear components are based on the use of ferritic steels; the expressions, tables, charts and equations were all developed from tests and analyses conducted for ferritic steels. Because of the nature of the Code, design with thin aluminum requires analytical approaches that do not directly follow the Code. The intent of this report is to present a methodology comparable to the ASME Code for ensuring the prevention of nonductile fracture of the CPBT in the ANS reactor. 6061-T6 aluminum is known to be a relatively brittle material; the linear elastic fracture mechanics (LEFM) approach is utilized to determine allowable flaw sizes for the CPBT. A J-analysis following the procedure developed by the Electric Power Research Institute was conducted as a check; the results matched those for the LEFM analysis for the cases analyzed. Since 6061-T6 is known to embrittle when irradiated, the reduction in K Q due to irradiation is considered in the analysis. In anticipation of probable requirements regarding maximum allowable flaw size, a survey of nondestructive inspection capabilities is also presented. A discussion of probabilistic fracture mechanics approaches, principally Monte Carlo techniques, is included in this report as an introduction to what quantifying the probability of nonductile failure of the CPBT may entail

  5. Evidence for the interior evolution of Ceres from geologic analysis of fractures

    Science.gov (United States)

    Scully, Jennifer E. C.; Buczkowski, Debra; Schmedemann, Nico; Raymond, Carol A.; Castillo-Rogez, Julie C.; Scott King,; Bland, Michael T.; Ermakov, Anton; O'Brien, D.P.; Marchi, S.; Longobardo, A.; Russell, C.T.; Fu, R.R.; Neveu, M.

    2017-01-01

    Ceres is the largest asteroid belt object, and the Dawn spacecraft observed Ceres since 2015. Dawn observed two morphologically distinct linear features on Ceres's surface: secondary crater chains and pit chains. Pit chains provide unique insights into Ceres's interior evolution. We interpret pit chains called the Samhain Catenae as the surface expression of subsurface fractures. Using the pit chains' spacings, we estimate that the localized thickness of Ceres's fractured, outer layer is approximately ≥58 km, at least ~14 km greater than the global average. We hypothesize that extensional stresses, induced by a region of upwelling material arising from convection/diapirism, formed the Samhain Catenae. We derive characteristics for this upwelling material, which can be used as constraints in future interior modeling studies. For example, its predicted location coincides with Hanami Planum, a high-elevation region with a negative residual gravity anomaly, which may be surficial evidence for this proposed region of upwelling material.

  6. Mapping the prescriptiome to fractures in men--a national analysis of prescription history and fracture risk

    DEFF Research Database (Denmark)

    Abrahamsen, B; Brixen, K; Abrahamsen, B

    2009-01-01

    SUMMARY: A nationwide case-control study was performed in 62,865 men aged 50+ using fracture data from the national hospital discharge register to screen all redeemed prescriptions in the past 5 years for significant mapping to fracture risk, employing measures to control for false discovery rate....... INTRODUCTION: Osteoporosis in men is frequently related to alcohol abuse, hypogonadism, hypercalciuria, or the use of glucocorticoids. Very limited information is available on the impact of other medications on fracture risk in men. METHODS: We conducted a nationwide population-based case-control study...... collecting fracture data from the Danish National Hospital Discharge Register and prescriptions from the National Prescriptions Database (1995-2000). We included men aged 50+ years, with hospital-treated fractures in the year 2000 (n = 15,716), and age- and sex-matched controls (n = 47,149). RESULTS: We...

  7. Finite element analysis of cutting tools prior to fracture in hard turning operations

    International Nuclear Information System (INIS)

    Cakir, M. Cemal; I Sik, Yahya

    2005-01-01

    In this work cutting FEA of cutting tools prior to fracture is investigated. Fracture is the catastrophic end of the cutting edge that should be avoided for the cutting tool in order to have a longer tool life. This paper presents finite element modelling of a cutting tool just before its fracture. The data used in FEA are gathered from a tool breakage system that detects the fracture according to the variations of the cutting forces measured by a three-dimensional force dynamometer. The workpiece material used in the experiments is cold work tool steel, AISI O1 (60 HRC) and the cutting tool material is uncoated tungsten carbide (DNMG 150608). In order to investigate the cutting tool conditions in longitudinal external turning operations prior to fracture, static and dynamic finite element analyses are conducted. After the static finite element analysis, the modal and harmonic response analyses are carried on and the dynamic behaviours of the cutting tool structure are investigated. All FE analyses were performed using a commercial finite element package ANSYS

  8. Natural time analysis of critical phenomena: The case of pre-fracture electromagnetic emissions

    Energy Technology Data Exchange (ETDEWEB)

    Potirakis, S. M. [Department of Electronics, Technological Education Institute (TEI) of Piraeus, 250 Thivon and P. Ralli, Aigaleo, Athens GR-12244 (Greece); Karadimitrakis, A. [Department of Physics, Section of Electronics, Computers, Telecommunications and Control, University of Athens, Panepistimiopolis, Zografos, Athens GR-15784 (Greece); Eftaxias, K. [Department of Physics, Section of Solid State Physics, University of Athens, Panepistimiopolis, Zografos, Athens GR-15784 (Greece)

    2013-06-15

    Criticality of complex systems reveals itself in various ways. One way to monitor a system at critical state is to analyze its observable manifestations using the recently introduced method of natural time. Pre-fracture electromagnetic (EM) emissions, in agreement to laboratory experiments, have been consistently detected in the MHz band prior to significant earthquakes. It has been proposed that these emissions stem from the fracture of the heterogeneous materials surrounding the strong entities (asperities) distributed along the fault, preventing the relative slipping. It has also been proposed that the fracture of heterogeneous material could be described in analogy to the critical phase transitions in statistical physics. In this work, the natural time analysis is for the first time applied to the pre-fracture MHz EM signals revealing their critical nature. Seismicity and pre-fracture EM emissions should be two sides of the same coin concerning the earthquake generation process. Therefore, we also examine the corresponding foreshock seismic activity, as another manifestation of the same complex system at critical state. We conclude that the foreshock seismicity data present criticality features as well.

  9. Natural time analysis of critical phenomena: the case of pre-fracture electromagnetic emissions.

    Science.gov (United States)

    Potirakis, S M; Karadimitrakis, A; Eftaxias, K

    2013-06-01

    Criticality of complex systems reveals itself in various ways. One way to monitor a system at critical state is to analyze its observable manifestations using the recently introduced method of natural time. Pre-fracture electromagnetic (EM) emissions, in agreement to laboratory experiments, have been consistently detected in the MHz band prior to significant earthquakes. It has been proposed that these emissions stem from the fracture of the heterogeneous materials surrounding the strong entities (asperities) distributed along the fault, preventing the relative slipping. It has also been proposed that the fracture of heterogeneous material could be described in analogy to the critical phase transitions in statistical physics. In this work, the natural time analysis is for the first time applied to the pre-fracture MHz EM signals revealing their critical nature. Seismicity and pre-fracture EM emissions should be two sides of the same coin concerning the earthquake generation process. Therefore, we also examine the corresponding foreshock seismic activity, as another manifestation of the same complex system at critical state. We conclude that the foreshock seismicity data present criticality features as well.

  10. Natural time analysis of critical phenomena: The case of pre-fracture electromagnetic emissions

    International Nuclear Information System (INIS)

    Potirakis, S. M.; Karadimitrakis, A.; Eftaxias, K.

    2013-01-01

    Criticality of complex systems reveals itself in various ways. One way to monitor a system at critical state is to analyze its observable manifestations using the recently introduced method of natural time. Pre-fracture electromagnetic (EM) emissions, in agreement to laboratory experiments, have been consistently detected in the MHz band prior to significant earthquakes. It has been proposed that these emissions stem from the fracture of the heterogeneous materials surrounding the strong entities (asperities) distributed along the fault, preventing the relative slipping. It has also been proposed that the fracture of heterogeneous material could be described in analogy to the critical phase transitions in statistical physics. In this work, the natural time analysis is for the first time applied to the pre-fracture MHz EM signals revealing their critical nature. Seismicity and pre-fracture EM emissions should be two sides of the same coin concerning the earthquake generation process. Therefore, we also examine the corresponding foreshock seismic activity, as another manifestation of the same complex system at critical state. We conclude that the foreshock seismicity data present criticality features as well.

  11. [Association between hip fractures and risk factors for osteoporosis. Multivariate analysis].

    Science.gov (United States)

    Masoni, Ana; Morosano, Mario; Tomat, María Florencia; Pezzotto, Stella M; Sánchez, Ariel

    2007-01-01

    In this observational, case-control study, 376 inpatients were evaluated in order to determine the association of risk factors (RF) and hip fracture; 151 patients had osteoporotic hip fracture (cases); the remaining were controls. Data were obtained from medical charts, and through a standardized questionnaire about RF. Mean age of the sample (+/- SD) was 80.6 +/- 8.1 years, without statistically significant difference between cases and controls; the female:male ratio was 3:1 in both groups. Fractured women were older than men (82.5 +/- 8.1 vs. 79.7 +/- 7.2 years, respectively; p household duties was a RF (p = 0.007), which was absent in males. In multivariate analysis, the following RF were significantly more frequent: Cognitive impairment (p = 0.001), and previous falls (p < 0.0001); whereas the following protective factors were significantly different from controls: Calcium intake during youth (p < 0.0001), current calcium intake (p < 0.0001), and mechanical aid for walking (p < 0.0001). Evaluation of RF and protective factors may contribute to diminish the probability of hip fracture, through a modification of personal habits, and measures to prevent falls among elderly adults. Present information can help to develop local and national population-based strategies to diminish the burden of hip fractures for the health system.

  12. Directional semivariogram analysis to identify and rank controls on the spatial variability of fracture networks

    Science.gov (United States)

    Hanke, John R.; Fischer, Mark P.; Pollyea, Ryan M.

    2018-03-01

    In this study, the directional semivariogram is deployed to investigate the spatial variability of map-scale fracture network attributes in the Paradox Basin, Utah. The relative variability ratio (R) is introduced as the ratio of integrated anisotropic semivariogram models, and R is shown to be an effective metric for quantifying the magnitude of spatial variability for any two azimuthal directions. R is applied to a GIS-based data set comprising roughly 1200 fractures, in an area which is bounded by a map-scale anticline and a km-scale normal fault. This analysis reveals that proximity to the fault strongly influences the magnitude of spatial variability for both fracture intensity and intersection density within 1-2 km. Additionally, there is significant anisotropy in the spatial variability, which is correlated with trends of the anticline and fault. The direction of minimum spatial correlation is normal to the fault at proximal distances, and gradually rotates and becomes subparallel to the fold axis over the same 1-2 km distance away from the fault. We interpret these changes to reflect varying scales of influence of the fault and the fold on fracture network development: the fault locally influences the magnitude and variability of fracture network attributes, whereas the fold sets the background level and structure of directional variability.

  13. A new approach to tracer transport analysis: From fracture systems to strongly heterogeneous porous media

    International Nuclear Information System (INIS)

    Tsang, Chin-Fu.

    1989-02-01

    Many current development and utilization of groundwater resources include a study of their flow and transport properties. These properties are needed in evaluating possible changes in groundwater quality and potential transport of hazardous solutes through the groundwater system. Investigation of transport properties of fractured rocks is an active area of research. Most of the current approaches to the study of flow and transport in fractured rocks cannot be easily used for analysis of tracer transport field data. A new approach is proposed based on a detailed study of transport through a fracture of variable aperture. This is a two-dimensional strongly heterogeneous permeable system. It is suggested that tracer breakthrough curves can be analyzed based on an aperture or permeability probability distribution function that characterizes the tracer flow through the fracture. The results are extended to a multi-fracture system and can be equally applied to a strongly heterogeneous porous medium. Finally, the need for multi-point or line and areal tracer injection and observation tests is indicated as a way to avoid the sensitive dependence of point measurements on local permeability variability. 30 refs., 15 figs

  14. Analysis of fluid flow and solute transport though a single fracture intersecting a canister: comparison between fractal and Gaussian fractures

    International Nuclear Information System (INIS)

    Liu, L.; Neretnieks, I.

    2005-01-01

    Full text of publication follows: Canisters with spent fuel will be deposited in fractured crystalline rock in the Swedish concept for a final repository. The fractures intersect the canister holes at different angles and they have variable apertures and therefore locally varying flowrates. Our previous model with fractures with a constant aperture and a 90 deg. intersection angle is now extended to arbitrary intersection angles and stochastically variable apertures. It is shown the previous basic model can be simply amended to account for these effects. The mean and the standard deviation of the water flowrate in the fractures are obtained from the statistics of the aperture variations by a simple formula. Likewise, the statistical form of distribution of the so-called 'equivalent flowrate', which describes the mass transfer of solutes between the canister and the flowing water, is also obtained by a simple relation. These simple statistical relations obviate the need to simulate each fracture that intersects a canister in great detail. The water flowrate and the equivalent flowrate of a fracture are instead taken from the simple distributions presented in this work. This allows the use of complex fractures also in very large fracture network models used in performance assessment. The distributions have been obtained by generating a multitude of fractures and by studying their flow and transport properties. Fractal as well as Gaussian aperture distributions have been studied. It has been found that the distributions of the volumetric and the equivalent flow rates are all close to the Normal for both types of fractures, with the mean of the distribution of the volumetric flow rate being determined solely by the hydraulic aperture, and that of the equivalent flow rate being determined by the mechanical aperture. Moreover, the standard deviation of the volumetric flow rates of the many realizations increases with increasing roughness and spatial correlation length of

  15. Fracture Mechanics Assessment for Different Notch Sizes Using Finite Element Analysis Based on Ductile Failure Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Keun Hyung; Jeon, Jun Young; Han, Jae Jun; Nam, Hyun Suk; Lee, Dae Young; Kim, Yun Jae [Korea Univ., Seoul (Korea, Republic of)

    2016-08-15

    In this study, notch defects are evaluated using fracture mechanics. To understand the effects of notch defects, FE analysis is conducted to predict the limit load and J-integral for middle-cracked and single-edge cracked plates with various sizes of notch under tension and bending. As the radius of the notch increases, the energy release rate also increases, although the limit load remains constant. The values of fracture toughness(J{sub IC}) of SM490A are determined for various notch radii through FE simulation instead of conducting an experiment. As the radius of the notch increases, the energy release rate also increases, together with a more significant increase in fracture toughness. To conclude, as the notch radius increases, the resistance to crack propagation also increases.

  16. Real frequency of ordinary and atypical sub-trochanteric and diaphyseal fractures in France based on X-rays and medical file analysis.

    Science.gov (United States)

    Beaudouin-Bazire, Constance; Dalmas, Noémie; Bourgeois, Julie; Babinet, Antoine; Anract, Philippe; Chantelot, Christophe; Farizon, Frédéric; Chopin, Florence; Briot, Karine; Roux, Christian; Cortet, Bernard; Thomas, Thierry

    2013-03-01

    Atypical sub-trochanteric and femoral shaft fractures have been reported in patients treated with bisphosphonates. Their incidence has been determined from registered data analysis using international codes. Therefore, the aim of our study was to estimate the real frequency of typical and atypical sub-trochanteric or diaphyseal fractures, based on radiological and clinical data compared to registered data. In the registers of three large French University Hospitals, patients identified with International Classification of Diseases, 10th Revision diagnosis codes for sub-trochanteric or diaphyseal fracture were selected. Frequencies of ordinary and atypical fractures were calculated after both registered data, radiological and clinical files analysis. Among the 4592 patients hospitalized for a femoral fracture over 5 years, 574 were identified to have had a sub-trochanteric or femoral shaft fracture. 47.7% of the sub-trochanteric and femoral shaft fractures were misclassified, predominantly in the sub-trochanteric fractures subset. 12 patients had an atypical fracture (4% of the sub-trochanteric and femoral shaft fractures) and 11 fractures presented radiological features of atypical fractures, whereas clinical files analysis revealed they were pathological or traumatic fractures. Atypical fractures frequency is very low. Because of their low frequency and the unreliability of registered databases, the risk of atypical fractures is very difficult to estimate retrospectively. A prospective study is needed to clarify the risk factors associated with these fractures. Copyright © 2012 Société française de rhumatologie. Published by Elsevier SAS. All rights reserved.

  17. Application of elastic and elastic-plastic fracture mechanics methods to surface flaws

    Science.gov (United States)

    McCabe, Donald E.; Ernst, Hugo A.; Newman, James C., Jr.

    Fuel tanks that are a part of the External Tank assembly for the Space Shuttle are made of relatively thin 2219-T87 aluminum plate. These tanks contain about 917 m of fusion weld seam, all of which is nondestructively inspected for flaws and all those found are repaired. The tanks are subsequently proof-tested to a pressure that is sufficiently severe to cause weld metal yielding in a few local regions of the weld seam. The work undertaken in the present project was to develop a capability to predict flaw growth from undetected surface flaws that are assumed to be located in the highly stressed regions. The technical challenge was to develop R-curve prediction capability for surface cracks in specimens that contain the flaws of unusual sizes and shapes deemed to be of interest. The test techniques developed and the elastic-plastic analysis concepts adopted are presented. The flaws of interest were quite small surface cracks that were narrow-deep ellipses that served to exacerbate the technical difficulties involved.

  18. 3-D fracture analysis using a partial-reduced integration scheme

    International Nuclear Information System (INIS)

    Leitch, B.W.

    1987-01-01

    This paper presents details of 3-D elastic-plastic analyses of axially orientated external surface flaw in an internally pressurized thin-walled cylinder and discusses the variation of the J-integral values around the crack tip. A partial-reduced-integration-penalty method is introduced to minimize this variation of the J-integral near the crack tip. Utilizing 3-D symmetry, an eighth segment of a tube containing an elliptically shaped external surface flaw is modelled using 20-noded isoparametric elements. The crack-tip elements are collapsed to form a 1/r stress singularity about the curved crack front. The finite element model is subjected to internal pressure and axial pressure-generated loads. The virtual crack extension method is used to determine linear elastic stress intensity factors from the J-integral results at various points around the crack front. Despite the different material constants and the thinner wall thickness in this analysis, the elastic results compare favourably with those obtained by other researchers. The nonlinear stress-strain behaviour of the tube material is modelled using an incremental theory of plasticity. Variations of the J-integral values around the curved crack front of the 3-D flaw were seen. These variations could not be resolved by neglecting the immediate crack-tip elements J-integral results in favour of the more remote contour paths or else smoothed out when all the path results are averaged. Numerical incompatabilities in the 20-noded 3-D finite elements used to model the surface flaw were found. A partial-reduced integration scheme, using a combination of full and reduced integration elements, is proposed to determine J-integral results for 3-D fracture analyses. This procedure is applied to the analysis of an external semicircular surface flaw projecting halfway into the tube wall thickness. Examples of the J-integral values, before and after the partial-reduced integration method is employed, are given around the

  19. Analysis of gravity data using trend surfaces

    Science.gov (United States)

    Asimopolos, Natalia-Silvia; Asimopolos, Laurentiu

    2013-04-01

    In this paper we have developed algorithms and related software programs for calculating of trend surfaces of higher order. These methods of analysis of trends, like mobile media applications are filtration systems for geophysical data in surface. In particular we presented few case studies for gravity data and gravity maps. Analysis with polynomial trend surfaces contributes to the recognition, isolation and measurement of trends that can be represented by surfaces or hyper-surfaces (in several sizes), thus achieving a separation in regional variations and local variations. This separation is achieved by adjusting the trend function at different values. Trend surfaces using the regression analysis satisfy the criterion of least squares. The difference between the surface of trend and the observed value in a certain point is the residual value. Residual sum of squares of these values should be minimal as the criterion of least squares. The trend surface is considered as regional or large-scale and the residual value will be regarded as local or small-scale component. Removing the regional trend has the effect of highlighting local components represented by residual values. Surface analysis and hyper-surfaces principles are applied to the surface trend and any number of dimensions. For hyper-surfaces we can work with polynomial functions with four or more variables (three variables of space and other variables for interest parameters) that have great importance in some applications. In the paper we presented the mathematical developments about generalized trend surfaces and case studies about gravimetric data. The trend surfaces have the great advantage that the effect of regional anomalies can be expressed as analytic functions. These tendency surfaces allows subsequent mathematical processing and interesting generalizations, with great advantage to work with polynomial functions compared with the original discrete data. For gravity data we estimate the depth of

  20. Fracture mechanical materials characterisation

    International Nuclear Information System (INIS)

    Wallin, K.; Planman, T.; Nevalainen, M.

    1998-01-01

    The experimental fracture mechanics development has been focused on the determination of reliable lower-bound fracture toughness estimates from small and miniature specimens, in particular considering the statistical aspects and loading rate effects of fracture mechanical material properties. Additionally, materials aspects in fracture assessment of surface cracks, with emphasis on the transferability of fracture toughness data to structures with surface flaws have been investigated. Further a modified crack-arrest fracture toughness test method, to increase the effectiveness of testing, has been developed. (orig.)

  1. Fracture analysis of an Eocene reservoir in Eastern Tunisia by coupling Terrestrial Laser Scanning with GigaPan Technology and seismic attribute

    Science.gov (United States)

    Mastouri, Raja; Guerin, Antoine; Marchant, Robin; Derron, Marc-Henri; Boulares, Achref; Lazzez, Marzouk; Marillier, François; Jaboyedoff, Michel; Bouaziz, Samir

    2015-04-01

    It is usually not possible to study in situ fractures and faults of oil reservoirs. Then outcropping reservoir analogues are used instead. For this purpose, Terrestrial Laser Scanning (TLS) has been increasingly used for some years in the petroleum sector. The formations El Garia and Reineche make the Eocene oil reservoir of Eastern Tunisia. The fracturing of these formations has been analyzed on the surface by TLS on a reservoir analogue outcrop and in the depth by 3D seismic data. TLS datasets provide clear information on fracture geometry distribution (spacing and persistence), connectivity and joint orientation. These results were then compared to structures observed in depth with seismic data. The reservoir analogues are the Ousselat cliff (formation El Garia) and the Damous quarry (formation Reineche). Those two sites are made of marine limestone rich in large foraminifers, gastropods and nummulites. Fieldwork, TLS acquisitions and high-resolution GigaPan panoramas were put together to create digital outcrop models. A total of 9 scans at 3 different survey positions were carried out. Firstly, the data processing (cleaning, alignment and georeferencing of the raw point clouds) was carried out using the Polyworks software. Secondly, we draped Gigapixel pictures on the triangular mesh generated with 3DReshaper to produce relief shading. This process produces a photorealistic model that gives a 3D representation of the outcrop. Finally, Coltop3D was used to identify the different sets of discontinuities and to measure their orientations. Furthermore, we used some 3D seismic attribute data to interpret approximately 60 fractures and faults at the top of the Eocene reservoir. The Coltop3D analysis of the Ousselat cliff shows 5 sets of joints and fractures, with different dips and dip directions. They all strike in directions NW-SE, NNE-SSW, NE-SW and ENE-WSW. Using the photorealistic model, we measured approximately 120 fracture spacings ranging from 1.75m to 10m

  2. Acquirement of true stress-strain curve using true fracture strain obtained by tensile test and FE analysis

    International Nuclear Information System (INIS)

    Lee, Kyoung Yoon; Kim, Tae Hyung; Lee, Hyung Yil

    2009-01-01

    In this work, we predict a true fracture strain using load-displacement curves from tensile test and Finite Element Analysis (FEA), and suggest a method for acquiring true Stress-Strain (SS) curves by predicted fracture strain. We first derived the true SS curve up to necking point from load-displacement curve. As the beginning, the posterior necking part of true SS curve is linearly extrapolated with the slope at necking point. The whole SS curve is then adopted for FE simulation of tensile test. The Bridgman factor or suitable plate correction factors are applied to pre and post FEA. In the load-true strain curve from FEA, the true fracture strain is determined as the matching point to test fracture load. The determined true strain is validated by comparing with test fracture strain. Finally, we complete the true SS curve by combining the prior necking part and linear part, the latter of which connects necking and predicted fracture points.

  3. Acquirement of true stress-strain curve using true fracture strain obtained by tensile test and FE analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyoung Yoon; Kim, Tae Hyung; Lee, Hyung Yil [Sogang University, Seoul (Korea, Republic of)

    2009-07-01

    In this work, we predict a true fracture strain using load-displacement curves from tensile test and Finite Element Analysis (FEA), and suggest a method for acquiring true Stress-Strain (SS) curves by predicted fracture strain. We first derived the true SS curve up to necking point from load-displacement curve. As the beginning, the posterior necking part of true SS curve is linearly extrapolated with the slope at necking point. The whole SS curve is then adopted for FE simulation of tensile test. The Bridgman factor or suitable plate correction factors are applied to pre and post FEA. In the load-true strain curve from FEA, the true fracture strain is determined as the matching point to test fracture load. The determined true strain is validated by comparing with test fracture strain. Finally, we complete the true SS curve by combining the prior necking part and linear part, the latter of which connects necking and predicted fracture points.

  4. Acquirement of True Stress-strain Curve Using True Fracture Strain Obtained by Tensile Test and FE Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyoung Yoon; Lee, Hyung Yil [Sogang University, Seoul (Korea, Republic of); Kim, Tae Hyung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2009-10-15

    In this work, we predict a true fracture strain using load-displacement curves from tensile test and finite element analysis (FEA), and suggest a method for acquiring true stress-strain (SS) curves by predicted fracture strain. We first derived the true SS curve up to necking point from load-displacement curve. As the beginning, the posterior necking part of true SS curve is linearly extrapolated with the slope at necking point. The whole SS curve is then adopted for FE simulation of tensile test. The Bridgman factor or suitable plate correction factors are applied to pre and post FEA. In the load-true strain curve from FEA, the true fracture strain is determined as the matching point to test fracture load. The determined true strain is validated by comparing with test fracture strain. Finally, we complete the true SS curve by combining the prior necking part and linear part, the latter of which connects necking and predicted fracture points.

  5. Fathoms Below: Propagation of Deep Water-driven Fractures and Implications for Surface Expression and Temporally-varying Activity at Europa

    Science.gov (United States)

    Walker, C. C.; Craft, K.; Schmidt, B. E.

    2015-12-01

    The fracture and failure of Europa's icy shell are not only observable scars of variable stress and activity throughout its evolution, they also serve key as mechanisms in the interaction of surface and subsurface material, and thus crucial aspects of the study of crustal overturn and ice shell habitability. Galileo images, our best and only reasonable-resolution views of Europa until the Europa Multiple Flyby Mission arrives in the coming decades, illustrates a single snapshot in time in Europa's history from which we deduce many temporally-based hypotheses. One of those hypotheses, which we investigate here, is that sub-surface water-both in the form of Great Lake-sized perched water pockets in the near-surface and the larger global ocean below-drives the deformation, fracture, and failure of the surface. Using Galileo's snapshot in time, we use a 2D/3D hydraulic fracturing model to investigate the propagation of vertical fractures upward into the ice shell, motion of water within and between fractures, and the subsequent break-up of ice over shallow water, forming the chaos regions and other smaller surface features. We will present results from a cohesive fragmentation model to determine the time over which chaos formation occurs, and use a fracking model to determine the time interval required to allow water to escape from basal fractures in the ice shell. In determining the style, energy, and timescale of these processes, we constrain temporal variability in observable activity and topography at the surface. Finally, we compare these results to similar settings on Earth-Antarctica-where we have much higher resolution imagery and observations to better understand how sub-surface water can affect ice surface morphology, which most certainly have implications for future flyby and surface lander exploration.

  6. Fractal Characteristics of Rock Fracture Surface under Triaxial Compression after High Temperature

    Directory of Open Access Journals (Sweden)

    X. L. Xu

    2016-01-01

    Full Text Available Scanning Electron Microscopy (SEM test on 30 pieces of fractured granite has been researched by using S250MK III SEM under triaxial compression of different temperature (25~1000°C and confining pressure (0~40 MPa. Research results show that (1 the change of fractal dimension (FD of rock fracture with temperature is closely related to confining pressure, which can be divided into two categories. In the first category, when confining pressure is in 0~30 MPa, FD fits cubic polynomial fitting curve with temperature, reaching the maximum at 600°C. In the second category, when confining pressure is in 30~40 MPa, FD has volatility with temperature. (2 The FD of rock fracture varies with confining pressure and is also closely related to the temperature, which can be divided into three categories. In the first category, FD has volatility with confining pressure at 25°C, 400°C, and 800°C. In the second category, it increases exponentially at 200°C and 1000°C. In the third category, it decreases exponentially at 600°C. (3 It is found that 600°C is the critical temperature and 30 MPa is the critical confining pressure of granite. The rock transfers from brittle to plastic phase transition when temperature exceeds 600°C and confining pressure exceeds 30 MPa.

  7. Evaluation of liquid droplet impingement erosion by micro-scale fracture analysis

    International Nuclear Information System (INIS)

    Kitajima, Yasumi; Hagiwara, Tsuyoshi; Jimbo, Masakazu; Endo, Tetsuo

    2008-01-01

    Several estimation methods based on round-robin experiments and/or actual plant experiences have been used to estimate erosion by liquid drop impingement (LDI). However, in recent years, due to developments on computer technology, it is possible to utilize large scale computational analyses. This study proposes a method for the evaluation of LDI erosion by means of computational fracture analysis using results (diameters, velocity, or speed of drops) of fluid dynamics analysis. (author)

  8. Computational methods for fracture analysis of heavy-section steel technology (HSST) pressure vessel experiments

    International Nuclear Information System (INIS)

    Bass, B.R.; Bryan, R.H.; Bryson, J.W.; Merkle, J.G.

    1983-01-01

    This paper summarizes the capabilities and applications of the general-purpose and special-purpose computer programs that have been developed for use in fracture mechanics analyses of HSST pressure vessel experiments. Emphasis is placed on the OCA/USA code, which is designed for analysis of pressurized-thermal-shock (PTS) conditions, and on the ORMGEN/ADINA/ORVIRT system which is used for more general analysis. Fundamental features of these programs are discussed, along with applications to pressure vessel experiments

  9. Mandibular fractures: a comparative analysis between young and adult patients in the southeast region of Turkey

    Directory of Open Access Journals (Sweden)

    Serhat Atilgan

    2010-02-01

    Full Text Available OBJECTIVE: The purpose of this study was to review and compare the differences between mandibular fractures in young and adult patients. MATERIAL AND METHODS: Patients treated at the Oral and Maxillofacial Department of Dicle University during a five-year period between 2000 and 2005 were retrospectively evaluated with respect to age groups, gender, etiology, localization and type of fractures, treatment methods and complications. RESULTS: 532 patients were included in the study, 370 (70% males and 162 (30% females, with a total of 744 mandibular fractures. The mean age of young patients was 10, with a male-female ratio of 2:1. The mean age of adult patients was 28, with a male-female ratio of 3:1. The most common causes of injury were falls (65% in young patients and traffic accidents (38% in adults. The most common fracture sites were the symphysis (35% and condyle (36% in young patients, and the symphysis in adults (36%. Mandibular fractures were generally treated by arch bar and maxillomandibular fixation in both young (67% and adult (39% patients, and 43% of the adult patients were treated by open reduction and internal fixation. CONCLUSION: There was a similar gender, monthly and type of treatment distribution in both young and adult patients in the southeast region of Turkey. However, there were differences regarding age, etiology and fracture site. These findings between young and adult patients are broadly similar to those from other studies. Analysis of small differences may be an important factor in assessing educational and socioeconomic environments.

  10. Effect of anodic surface treatment on PAN-based carbon fiber and its relationship to the fracture toughness of the carbon fiber-reinforced polymer composites

    DEFF Research Database (Denmark)

    Sarraf, Hamid; Skarpova, Ludmila

    2008-01-01

    The effect of anodic surface treatment on the polyacrylonitrile (PAN)-based carbon fibers surface properties and the mechanical behavior of the resulting carbon fiber-polymer composites has been studied in terms of the contact angle measurements of fibers and the fracture toughness of composites...... in the fiber surface nature and the mechanical interfacial properties between the carbon fiber and epoxy resin matrix of the resulting composites, i.e., the fracture toughness. We suggest that good wetting plays an important role in improving the degree of adhesion at interfaces between fibers and matrices...

  11. Analysis of patterns and treatment strategies for mandibular condyle fractures: review of 175 condyle fractures with review of literature.

    Science.gov (United States)

    Reddy, N Viveka V; Reddy, P Bhaskar; Rajan, Ritesh; Ganti, Srinivas; Jhawar, D K; Potturi, Abhinand; Pradeep

    2013-09-01

    This study aims to evaluate incidence, patterns and epidemiology of mandibular condylar fractures (MCF) to propose a treatment strategy for managing MCF and analyze the factors which influence the outcome. One hundred and seventy-five MCF's were evaluated over a four year period and their pattern was recorded in terms of displacement, level of fracture, age of incidence and dental occlusion. Of the 2,718 facial bone fractures, MCF incidence was the third most common at 18.39 %. Of 175 MCF 58.8 % were unilateral and 41.12 % were bilateral. 67 % of bilateral fractures and 43.8 % of unilateral fractures were associated with midline symphysis and contralateral parasymphysis fractures respectively. Most of the MCF was seen in the age group of above 16 years and 50 % of them were at subcondylar level (below the neck of the condyle). Majority of MCF sustained due to inter personal violence were undisplaced (72.7 %) and contrary to this majority of MCF sustained during road traffic accident were displaced. 62.9 % of total fractures required open reduction and rigid fixation and 37.1 % were managed with closed reduction. 80 % of MCF managed with closed reduction were in the age group of below 16 years. From this study it can be concluded that the treatment algorithm proposed for managing MCF is reliable and easy to adopt. We observed that absolute indication for open reduction of MCF is inability to achieve satisfactory occlusion by closed method and absolute contraindication for open reduction is condylar head fracture irrespective of the age of the patient.

  12. Experimental analysis of quasi-static and dynamic fracture initiation toughness of gy4 armor steel material

    Science.gov (United States)

    Ren, Peng; Guo, Zitao

    Quasi-static and dynamic fracture initiation toughness of gy4 armour steel material are investigated using three point bend specimen. The modified split Hopkinson pressure bar (SHPB) apparatus with digital image correlation (DIC) system is applied to dynamic loading experiments. Full-field deformation measurements are obtained by using DIC to elucidate on the strain fields associated with the mechanical response. A series of experiments are conducted at different strain rate ranging from 10-3 s-1 to 103 s-1, and the loading rate on the fracture initiation toughness is investigated. Specially, the scanning electron microscope imaging technique is used to investigate the fracture failure micromechanism of fracture surfaces. The gy4 armour steel material fracture toughness is found to be sensitive to strain rate and higher for dynamic loading as compared to quasi-static loading. This work is supported by National Nature Science Foundation under Grant 51509115.

  13. Effects of multiple root canal usage on the surface topography and fracture of two different Ni-Ti rotary file systems.

    Science.gov (United States)

    Kottoor, Jojo; Velmurugan, Natanasabapathy; Gopikrishna, Velayutham; Krithikadatta, Jogikalmat

    2013-01-01

    The purpose of this study was to evaluate the effect of multiple root canal usage on the surface topography and fracture of Twisted File (TF) and ProTaper (PT) rotary Ni-Ti file systems, using scanning electron microscope (SEM). Ten sets of PT and TF instruments were used to prepare the mesial canals of mandibular first molars. TF 25, 0.06 taper and PT F1 instruments were analyzed by SEM when new and thereafter every three root canal usages. This sequence was repeated for both the TF and PT groups until 12 uses. Two images of the instrument were recorded, one of the instrument tip and the other 5 mm from the tip, both at × 100 magnification. The sequential use was continued till the instrument fractured and the number of root canal usages for the file to fracture was noted. All fracture surfaces were examined under the SEM. Fresh TF instruments showed no surface wear when compared to PT instruments (P 0.05), while at the 9 th usage TF showed a steep increase in the spiral distortion score when compared to PT (P < 0.05). PT instruments fractured at a mean root canal usage of 17.4, while TF instruments showed a mean root canal usage of 11.8. Fractographically, all the TF instruments failed due to torsion, while all the PT instruments failed because of cyclic fatigue. PT instruments showed more resistance to fracture than TF instruments.

  14. Modelling of surface stresses and fracturing during dyke emplacement: Application to the 2009 episode at Harrat Lunayyir, Saudi Arabia

    Science.gov (United States)

    Al Shehri, Azizah; Gudmundsson, Agust

    2018-05-01

    Correct interpretation of surface stresses and deformation or displacement during volcanotectonic episodes is of fundamental importance for hazard assessment and dyke-path forecasting. Here we present new general numerical models on the local stresses induced by arrested dykes. In the models, the crustal segments hosting the dyke vary greatly in mechanical properties, from uniform or non-layered (elastic half-spaces) to highly anisotropic (layers with strong contrast in Young's modulus). The shallow parts of active volcanoes and volcanic zones are normally highly anisotropic and some with open contacts. The numerical results show that, for a given surface deformation, non-layered (half-space) models underestimate the dyke overpressure/thickness needed and overestimate the likely depth to the tip of the dyke. Also, as the mechanical contrast between the layers increases, so does the stress dissipation and associated reduction in surface stresses (and associated fracturing). In the absence of open contacts, the distance between the two dyke-induced tensile and shear stress peaks (and fractures, if any) at the surface is roughly twice the depth to the tip of the dyke. The width of a graben, if it forms, should therefore be roughly twice the depth to the tip of the associated arrested dyke. When applied to the 2009 episode at Harrat Lunayyir, the main results are as follows. The entire 3-7 km wide fracture zone/graben formed during the episode is far too wide to have been generated by induced stresses of a single, arrested dyke. The eastern part of the zone/graben may have been generated by the inferred, arrested dyke, but the western zone primarily by regional extensional loading. The dyke tip was arrested at only a few hundred metres below the surface, the estimated thickness of the uppermost part of the dyke being between about 6 and 12 m. For the inferred dyke length (strike dimension) of about 14 km, this yields a dyke length/thickness ratio between 2400 and 1200

  15. PHOTOGRAMMETRIC TECHNIQUES FOR ROAD SURFACE ANALYSIS

    Directory of Open Access Journals (Sweden)

    V. A. Knyaz

    2016-06-01

    Full Text Available The quality and condition of a road surface is of great importance for convenience and safety of driving. So the investigations of the behaviour of road materials in laboratory conditions and monitoring of existing roads are widely fulfilled for controlling a geometric parameters and detecting defects in the road surface. Photogrammetry as accurate non-contact measuring method provides powerful means for solving different tasks in road surface reconstruction and analysis. The range of dimensions concerned in road surface analysis can have great variation from tenths of millimetre to hundreds meters and more. So a set of techniques is needed to meet all requirements of road parameters estimation. Two photogrammetric techniques for road surface analysis are presented: for accurate measuring of road pavement and for road surface reconstruction based on imagery obtained from unmanned aerial vehicle. The first technique uses photogrammetric system based on structured light for fast and accurate surface 3D reconstruction and it allows analysing the characteristics of road texture and monitoring the pavement behaviour. The second technique provides dense 3D model road suitable for road macro parameters estimation.

  16. Mechanical Property Measurements and Fracture Propagation Analysis of Longmaxi Shale by Micro-CT Uniaxial Compression

    Directory of Open Access Journals (Sweden)

    Minyue Zhou

    2018-05-01

    Full Text Available The mechanical properties and fracture propagation of Longmaxi shale loading under uniaxial compression were measured using eight cylindrical shale specimens (4 mm in diameter and 8 mm in height, with the bedding plane oriented at 0° and 90° to the axial loading direction, respectively, by micro computed tomography (micro-CT. Based on the reconstructed three-dimensional (3-D CT images of cracks, different stages of the crack growth process in the 0° and 90° orientation specimen were revealed. The initial crack generally occurred at relatively smaller loading force in the 0° bedding direction specimen, mainly in the form of tensile splitting along weak bedding planes. Shear sliding fractures were dominant in the specimens oriented at 90°, with a small number of parallel cracks occurring on the bedding plane. The average thickness and volume of cracks in the 90° specimen is higher than those for the specimen oriented at 0°. The geometrical characterization of fractures segmented from CT scan binary images shows that a specific surface area correlates with tortuosity at the different load stages of each specimen. The 3-D box-counting dimension (BCD calculations can accurately reflect crack evolution law in the shale. The results indicate that the cracks have a more complex pattern and rough surface at an orientation of 90°, due to crossed secondary cracks and shear failure.

  17. SURFACE ENERGY BALANCE OVER ORANGE ORCHARD USING SURFACE RENEWAL ANALYSIS

    Directory of Open Access Journals (Sweden)

    Salvatore Barbagallo

    2009-12-01

    Full Text Available Reliable estimation of surface sensible and latent heat flux is the most important process to appraise energy and mass exchange among atmosphere and biosphere. In this study the surface energy fluxes were measured over an irrigated orange orchard during 2005-2008 monitoring periods using a Surface Renewal- Energy Balance approach. The experimental area is located in a representative orchard growing area of eastern Sicily (Italy. The performance of Surface Renewal (SR analysis for estimating sensible heat flux (H was analysed and evaluated in terms of correlation with H fluxes from the eddy covariance (EC method. Study revealed that the mean available energy (RN- G and latent heat flux (LE were of about 300 W m-2 and 237 W m-2, respectively, during dry periods and unstable-case atmospheric conditions. The estimated crop coefficient Kc values for the orchard crop averaged close to 0.80, which is considerably higher than previous FAO studies that found the value to be 0.65 for citrus with 70% of ground cover. The intercepted photosynthetically active radiation (LI PAR by the crop was measured and relationships between LAI and crop coefficient (Kc were established.

  18. Vertebral Augmentation Involving Vertebroplasty or Kyphoplasty for Cancer-Related Vertebral Compression Fractures: An Economic Analysis.

    Science.gov (United States)

    2016-01-01

    Untreated vertebral compression fractures can have serious clinical consequences and impose a considerable impact on patients' quality of life and on caregivers. Since non-surgical management of these fractures has limited effectiveness, vertebral augmentation procedures are gaining acceptance in clinical practice for pain control and fracture stabilization. The objective of this analysis was to determine the cost-effectiveness and budgetary impact of kyphoplasty or vertebroplasty compared with non-surgical management for the treatment of vertebral compression fractures in patients with cancer. We performed a systematic review of health economic studies to identify relevant studies that compare the cost-effectiveness of kyphoplasty or vertebroplasty with non-surgical management for the treatment of vertebral compression fractures in adults with cancer. We also performed a primary cost-effectiveness analysis to assess the clinical benefits and costs of kyphoplasty or vertebroplasty compared with non-surgical management in the same population. We developed a Markov model to forecast benefits and harms of treatments, and corresponding quality-adjusted life years and costs. Clinical data and utility data were derived from published sources, while costing data were derived using Ontario administrative sources. We performed sensitivity analyses to examine the robustness of the results. In addition, a 1-year budget impact analysis was performed using data from Ontario administrative sources. Two scenarios were explored: (a) an increase in the total number of vertebral augmentation procedures performed among patients with cancer in Ontario, maintaining the current proportion of kyphoplasty versus vertebroplasty; and (b) no increase in the total number of vertebral augmentation procedures performed among patients with cancer in Ontario but an increase in the proportion of kyphoplasties versus vertebroplasties. The base case considered each of kyphoplasty and vertebroplasty

  19. Fracture Phenomena in Amorphous Selenium

    DEFF Research Database (Denmark)

    Lindegaard-Andersen, Asger; Dahle, Birgit

    1966-01-01

    Fracture surfaces of amorphous selenium broken in flexure at room temperature have been studied. The fracture velocity was found to vary in different regions of the fracture surface. Peculiar features were observed in a transition zone between fast and slower fracture. In this zone cleavage steps...

  20. Elastic, plastic, fracture analysis of masonry arches: A multi-span bridge case study

    Science.gov (United States)

    Lacidogna, Giuseppe; Accornero, Federico

    2018-01-01

    In this work a comparison is presented between elastic, plastic, and fracture analysis of the monumental arch bridge of Porta Napoli, Taranto (Italy). By means of a FEM model and applying the Mery's Method, the behavior of the curved structure under service loads is verified, while considering the Safe Theorem approach byHeyman, the ultimate carrying capacity of the structure is investigated. Moreover, by using Fracture Mechanics concepts, the damage process which takes place when the conditions assessed through linear elastic analysis are no longer valid, and before the set-in of the conditions established by means of the plastic limit analysis, is numerically analyzed. The study of these transitions returns an accurate and effective whole service life assessment of the Porta Napoli masonry arch bridge.

  1. Immediate versus delayed intramedullary nailing for open fractures of the tibial shaft: A multivariate analysis of factors affecting deep infection and fracture healing

    Directory of Open Access Journals (Sweden)

    Yokoyama Kazuhiko

    2008-01-01

    Full Text Available Background: The purpose of this study was to evaluate contributing factors affecting deep infection and fracture healing of open tibia fractures treated with locked intramedullary nailing (IMN by multivariate analysis. Materials and Methods: We examined 99 open tibial fractures (98 patients treated with immediate or delayed locked IMN in static fashion from 1991 to 2002. Multivariate analyses following univariate analyses were derived to determine predictors of deep infection, nonunion, and healing time to union. The following predictive variables of deep infection were selected for analysis: age, sex, Gustilo type, fracture grade by AO type, fracture location, timing or method of IMN, reamed or unreamed nailing, debridement time (≤6 h or> 6 h, method of soft-tissue management, skin closure time (≤1 week or> 1 week, existence of polytrauma (ISS< 18 or ISS≥18, existence of floating knee injury, and existence of superficial/pin site infection. The predictive variables of nonunion selected for analysis was the same as those for deep infection, with the addition of deep infection for exchange of pin site infection. The predictive variables of union time selected for analysis was the same as those for nonunion, excluding of location, debridement time, and existence of floating knee and superficial infection. Results: Six (6.1%; type II Gustilo n=1, type IIIB Gustilo n=5 of the 99 open tibial fractures developed deep infections. Multivariate analysis revealed that timing or method of IMN, debridement time, method of soft-tissue management, and existence of superficial or pin site infection significantly correlated with the occurrence of deep infection ( P < 0.0001. In the immediate nailing group alone, the deep infection rate in type IIIB + IIIC was significantly higher than those in type I + II and IIIA ( P = 0.016. Nonunion occurred in 17 fractures (20.3%, 17/84. Multivariate analysis revealed that Gustilo type, skin closure time, and

  2. Acidization of shales with calcite cemented fractures

    Science.gov (United States)

    Kwiatkowski, Kamil; Szymczak, Piotr; Jarosiński, Marek

    2017-04-01

    wormholes is the strongest when coating thickness is a few times larger than the initial aperture of the fracture. This leads to formation of favorable complex networks of wormholes which provide adequate transport of reactive fluids to fracture surfaces and - at the same time - are capable of supporting fracture surfaces. As a conclusion, acidization of the reactivated fractures with hydrochloric acid seems to be an attractive treatment to apply at fracking stage or later on as EGR. The results contribute to the discussion on the use of acidization to enhance the gas production in the shale reservoirs. This communication stresses the importance of the dissolution of calcite cement in natural fractures in shale formations, which are initially sealed and become reactivated during fracking. While this research is based on the analysis of fractures in the Pomeranian shale basin its results are general enough to be applicable to different formations worldwide.

  3. [Effect of 3D printing technology on pelvic fractures:a Meta-analysis].

    Science.gov (United States)

    Zhang, Yu-Dong; Wu, Ren-Yuan; Xie, Ding-Ding; Zhang, Lei; He, Yi; Zhang, Hong

    2018-05-25

    To evaluate the effect of 3D printing technology applied in the surgical treatment of pelvic fractures through the published literatures by Meta-analysis. The PubMed database, EMCC database, CBM database, CNKI database, VIP database and Wanfang database were searched from the date of database foundation to August 2017 to collect the controlled clinical trials in wich 3D printing technology was applied in preoperative planning of pelvic fracture surgery. The retrieved literatures were screened according to predefined inclusion and exclusion criteria, and quality evaluation were performed. Then, the available data were extracted and analyzed with the RevMan5.3 software. Totally 9 controlled clinical trials including 638 cases were chosen. Among them, 279 cases were assigned to the 3D printing technology group and 359 cases to the conventional group. The Meta-analysis results showed that the operative time[SMD=-2.81, 95%CI(-3.76, -1.85)], intraoperative blood loss[SMD=-3.28, 95%CI(-4.72, -1.85)] and the rate of complication [OR=0.47, 95%CI(0.25, 0.87)] in the 3D printing technology were all lower than those in the conventional group;the excellent and good rate of pelvic fracture reduction[OR=2.09, 95%CI(1.32, 3.30)] and postoperative pelvic functional restoration [OR=1.94, 95%CI(1.15, 3.28) in the 3D printing technology were all superior to those in the conventional group. 3D printing technology applied in the surgical treatment of pelvic fractures has the advantage of shorter operative time, less intraoperative blood loss and lower rate of complication, and can improve the quality of pelvic fracture reduction and the recovery of postoperative pelvic function. Copyright© 2018 by the China Journal of Orthopaedics and Traumatology Press.

  4. A study on deep geological environment for the radwaste disposal - Estimation of roughness for the quantitative analysis of fracture transmissivity

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jung Yul; Kim, J. Y.; Kim, Y. S.; Hyun, H. J. [Korea Institute of Geology, Mining and Materials, Taejon (Korea)

    2000-03-01

    Estimation of fracture roughness-as one of the basic hydraulic fracture parameters - is very important in assessing ground water flow described by using discrete fracture network modeling. Former manual estimation of the roughness for each fracture surface of drill cores is above all a tedious, time-consuming work and will often cause some ambiguities of roughness interpretation partly due to the subjective judgements of observers, and partly due to the measuring procedure itself. However, recently, indebt to the highly reliable Televiewer data for the fracture discrimination, it has led to a guess to develop a relationship between the traditional roughness method based on a linear profiles and the method from the Televiewer image based on a ellipsoidal profile. Hence, the aim of this work is to develop an automatic evaluation algorithm for measuring the roughness from the Televiewer images. A highly reliable software named 'RAF' has been developed and realized to the extent that its utility merits. In the developing procedure, various problems - such as the examination of a new base line(ellipsoidal) for measuring the unevenness of fracture, the elimination of overlapping fracture signatures or noise, the wavelet estimation according to the type of fractures and the digitalization of roughness etc. - were considered. With these consideration in mind, the newly devised algorithm for the estimation of roughness curves showed a great potential not only for avoiding ambiguities of roughness interpretation but also for the judgement of roughness classification. 12 refs., 23 figs. (Author)

  5. SECTION 6.2 SURFACE TOPOGRAPHY ANALYSIS

    DEFF Research Database (Denmark)

    Seah, M. P.; De Chiffre, Leonardo

    2005-01-01

    Surface physical analysis, i.e. topography characterisation, encompasses measurement, visualisation, and quantification. This is critical for both component form and for surface finish at macro-, micro- and nano-scales. The principal methods of surface topography measurement are stylus profilometry......, optical scanning techniques, and scanning probe microscopy (SPM). These methods, based on acquisition of topography data from point by point scans, give quantitative information of heights with respect to position. Based on a different approach, the so-called integral methods produce parameters...

  6. Specifications for surface reaction analysis apparatus

    International Nuclear Information System (INIS)

    Teraoka, Yuden; Yoshigoe, Akitaka

    2001-03-01

    A surface reaction analysis apparatus was installed at the JAERI soft x-ray beamline in the SPring-8 as an experimental end-station for the study of surface chemistry. The apparatus is devoted to the study concerning the influence of translational kinetic energy of incident molecules to chemical reactions on solid surfaces with gas molecules. In order to achieve the research purpose, reactive molecular scattering experiments and photoemission spectroscopic measurements using synchrotron radiation are performed in that apparatus via a supersonic molecular beam generator, an electron energy analyzer and a quadrupole mass analyzer. The detail specifications for the apparatus are described in this report. (author)

  7. Cement Leakage in Percutaneous Vertebral Augmentation for Osteoporotic Vertebral Compression Fractures: Analysis of Risk Factors.

    Science.gov (United States)

    Xie, Weixing; Jin, Daxiang; Ma, Hui; Ding, Jinyong; Xu, Jixi; Zhang, Shuncong; Liang, De

    2016-05-01

    The risk factors for cement leakage were retrospectively reviewed in 192 patients who underwent percutaneous vertebral augmentation (PVA). To discuss the factors related to the cement leakage in PVA procedure for the treatment of osteoporotic vertebral compression fractures. PVA is widely applied for the treatment of osteoporotic vertebral fractures. Cement leakage is a major complication of this procedure. The risk factors for cement leakage were controversial. A retrospective review of 192 patients who underwent PVA was conducted. The following data were recorded: age, sex, bone density, number of fractured vertebrae before surgery, number of treated vertebrae, severity of the treated vertebrae, operative approach, volume of injected bone cement, preoperative vertebral compression ratio, preoperative local kyphosis angle, intraosseous clefts, preoperative vertebral cortical bone defect, and ratio and type of cement leakage. To study the correlation between each factor and cement leakage ratio, bivariate regression analysis was employed to perform univariate analysis, whereas multivariate linear regression analysis was employed to perform multivariate analysis. The study included 192 patients (282 treated vertebrae), and cement leakage occurred in 100 vertebrae (35.46%). The vertebrae with preoperative cortical bone defects generally exhibited higher cement leakage ratio, and the leakage is typically type C. Vertebrae with intact cortical bones before the procedure tend to experience type S leakage. Univariate analysis showed that patient age, bone density, number of fractured vertebrae before surgery, and vertebral cortical bone were associated with cement leakage ratio (Pcement leakage are bone density and vertebral cortical bone defect, with standardized partial regression coefficients of -0.085 and 0.144, respectively. High bone density and vertebral cortical bone defect are independent risk factors associated with bone cement leakage.

  8. SCANNING ELECTRON-MICROSCOPIC EVALUATION OF THE FRACTURED SURFACES OF CANINE CALCULI FROM SUBSTRATA WITH DIFFERENT SURFACE FREE-ENERGY

    NARCIS (Netherlands)

    UYEN, HMW; JONGEBLOED, WL; BUSSCHER, HJ

    1991-01-01

    The strength of adhesion between dental calculus and enamel or dentin surfaces determines the ease with which the calculus can be removed by brushing or professional dental treatment. In this study, we examined the adhesion of canine calculi formed on substrata with different surface free energies

  9. Quantitative characterization of cleavage and hydrogen-assisted quasi-cleavage fracture surfaces with the use of confocal laser scanning microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Merson, E. [Institute of Advanced Technologies, Togliatti State University, 445667 (Russian Federation); Kudrya, A.V.; Trachenko, V.A. [Department of Physical Metallurgy and the Physics of Strength, NUST MISiS, Moscow 119490 (Russian Federation); Merson, D. [Institute of Advanced Technologies, Togliatti State University, 445667 (Russian Federation); Laboratory for Advanced Materials, Kazan Federal University, Naberezhnye Chelny 423812, Republic of Tatarstan (Russian Federation); Danilov, V. [Institute of Advanced Technologies, Togliatti State University, 445667 (Russian Federation); Vinogradov, A. [Institute of Advanced Technologies, Togliatti State University, 445667 (Russian Federation); Department of Engineering Design and Materials, Norwegian University of Science and Technology – NTNU, N-7491 Trondheim (Norway)

    2016-05-17

    “True” cleavage (TC) and quasi-cleavage (QC) fracture surfaces of low-carbon steel specimens tested in liquid nitrogen and after hydrogen charging respectively were investigated by quantitative confocal laser scanning microscopy (CLSM) and conventional scanning electron microscopy (SEM) with electron-backscattered diffraction (EBSD). Topological and crystallographic features of the TC fracture surface are found in good agreement with the generally accepted cleavage mechanism: TC facets diameters correspond to those of grains; the crack path strictly follows the crystallographic orientation of grains and the most of the cleavage cracks are parallel to {100} planes. On the 2D SEM images, the QC facets appeared resembling the TC ones in terms of river line patterns, shapes and sizes. However, the substantial differences between the topography of these two kinds of fracture surfaces were revealed by 3D CLSM: the average misorientation angle between QC facets and the roughness of the QC fracture surface were much lower than those measured for TC. It is demonstrated that all these features are attributed to the specific fracture mechanism operating during hydrogen-assisted cracking.

  10. Quantitative characterization of cleavage and hydrogen-assisted quasi-cleavage fracture surfaces with the use of confocal laser scanning microscopy

    International Nuclear Information System (INIS)

    Merson, E.; Kudrya, A.V.; Trachenko, V.A.; Merson, D.; Danilov, V.; Vinogradov, A.

    2016-01-01

    “True” cleavage (TC) and quasi-cleavage (QC) fracture surfaces of low-carbon steel specimens tested in liquid nitrogen and after hydrogen charging respectively were investigated by quantitative confocal laser scanning microscopy (CLSM) and conventional scanning electron microscopy (SEM) with electron-backscattered diffraction (EBSD). Topological and crystallographic features of the TC fracture surface are found in good agreement with the generally accepted cleavage mechanism: TC facets diameters correspond to those of grains; the crack path strictly follows the crystallographic orientation of grains and the most of the cleavage cracks are parallel to {100} planes. On the 2D SEM images, the QC facets appeared resembling the TC ones in terms of river line patterns, shapes and sizes. However, the substantial differences between the topography of these two kinds of fracture surfaces were revealed by 3D CLSM: the average misorientation angle between QC facets and the roughness of the QC fracture surface were much lower than those measured for TC. It is demonstrated that all these features are attributed to the specific fracture mechanism operating during hydrogen-assisted cracking.

  11. Fracture, roughness and phase transformation in CAD/CAM milling and subsequent surface treatments of lithium metasilicate/disilicate glass-ceramics.

    Science.gov (United States)

    Alao, Abdur-Rasheed; Stoll, Richard; Song, Xiao-Fei; Abbott, John R; Zhang, Yu; Abduo, Jaafar; Yin, Ling

    2017-10-01

    This paper studied surface fracture, roughness and morphology, phase transformations, and material removal mechanisms of lithium metasilicate/disilicate glass ceramics (LMGC/LDGC) in CAD/CAM-milling and subsequent surface treatments. LMGC (IPS e.max CAD) blocks were milled using a chairside dental CAD/CAM milling unit and then treated in sintering, polishing and glazing processes. X-ray diffraction was performed on all processed surfaces. Scanning electron microscopy (SEM) was applied to analyse surface fracture and morphology. Surface roughness was quantitatively characterized by the arithmetic average surface roughness R a and the maximum roughness R z using desktop SEM-assisted morphology analytical software. The CAD/CAM milling induced extensive brittle cracks and crystal pulverization on LMGC surfaces, which indicate that the dominant removal mechanism was the fracture mode. Polishing and sintering of the milled LMGC lowered the surface roughness (ANOVA, p 0.05). In comparison of all applied fabrication process routes, it is found that CAD/CAM milling followed by polishing and sintering produced the smoothest surface with R a = 0.12 ± 0.08µm and R z = 0.89 ± 0.26µm. Thus , it is proposed as the optimized process route for LMGC/LDGC in dental restorations. This route enables to manufacture LMGC/LDGC restorations with cost effectiveness, time efficiency, and improved surface quality for better occlusal functions and reduced bacterial plaque accumulation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Generalised fracture mechanics approach to the interfacial failure analysis of a bonded steel-concrete joint

    Czech Academy of Sciences Publication Activity Database

    De Corte, W.; Helincks, P.; Boel, V.; Klusák, Jan; Seitl, Stanislav; De Schutter, G.

    2017-01-01

    Roč. 11, č. 42 (2017), s. 147-160 ISSN 1971-8993 R&D Projects: GA MŠk(CZ) LQ1601; GA ČR(CZ) GA16-18702S Institutional support: RVO:68081723 Keywords : Epoxy adhesive * Fracture mechanics * Interfacial properties * Numerical study * Push-out test * Steel-concrete joint Subject RIV: JL - Materials Fatigue, Friction Mechanics OBOR OECD: Audio engineering, reliability analysis

  13. Surgical management for displaced pediatric proximal humeral fractures: a cost analysis

    OpenAIRE

    Shore, Benjamin J.; Hedequist, Daniel J.; Miller, Patricia E.; Waters, Peter M.; Bae, Donald S.

    2015-01-01

    Purpose The purpose of this investigation was to determine which of the following methods of fixation, percutaneous pinning (PP) or intramedullary nailing (IMN), was more cost-effective in the treatment of displaced pediatric proximal humeral fractures (PPHF). Methods: A retrospective cohort of surgically treated PPHF over a 12-year period at a single institution was performed. A decision analysis model was constructed to compare three surgical strategies: IMN versus percutaneous pinning leav...

  14. Shear bond strength and fracture analysis of human vs. bovine teeth.

    Directory of Open Access Journals (Sweden)

    Stefan Rüttermann

    Full Text Available PURPOSE: To evaluate if bovine enamel and dentin are appropriate substitutes for the respective human hard tooth tissues to test shear bond strength (SBS and fracture analysis. MATERIALS AND METHODS: 80 sound and caries-free human erupted third molars and 80 freshly extracted bovine permanent central incisors (10 specimens for each group were used to investigate enamel and dentine adhesion of one 2-step self-etch (SE and one 3-step etch and rinse (E&R product. To test SBS the buccal or labial areas were ground plane to obtain appropriate enamel or dentine areas. SE and E&R were applied and SBS was measured prior to and after 500 thermocycles between +5 and +55°C. Fracture analysis was performed for all debonded areas. RESULTS: ANOVA revealed significant differences of enamel and dentin SBS prior to and after thermocycling for both of the adhesives. SBS- of E&R-bonded human enamel increased after thermocycling but SE-bonded did not. Bovine enamel SE-bonded showed higher SBS after TC but E&R-bonded had lower SBS. No differences were found for human dentin SE- or E&R-bonded prior to or after thermocycling but bovine dentin SE-bonded increased whereas bovine dentine E&R-bonded decreased. Considering the totalized and adhesive failures, fracture analysis did not show significances between the adhesives or the respective tooth tissues prior to or after thermocycling. CONCLUSION: Although SBS was different on human and bovine teeth, no differences were found for fracture analysis. This indicates that solely conducted SBS on bovine substrate are not sufficient to judge the perfomance of adhesives, thus bovine teeth are questionnable as a substrate for shear bond testing.

  15. Ultra high vacuum fracture and transfer device for AES analysis of irradiated austenitic stainless steel

    International Nuclear Information System (INIS)

    Urie, M.W.; Panayotou, N.F.; Robinson, J.E.

    1980-01-01

    An ultrahigh vacuum fracture and transfer device for analysis of irradiated and non-irradiated SS 316 fuel cladding is described. Mechanical property tests used to study the behavior of cladding during reactor transient over-power conditions are reported. The stress vs temperature curves show minimal differences between unirradiated cladding and unfueled cladding. The fueled cladding fails at a lower temperature. All fueled specimens failed in an intergranular mode

  16. Calcium plus vitamin D supplementation and risk of fractures: an updated meta-analysis from the National Osteoporosis Foundation.

    Science.gov (United States)

    Weaver, C M; Alexander, D D; Boushey, C J; Dawson-Hughes, B; Lappe, J M; LeBoff, M S; Liu, S; Looker, A C; Wallace, T C; Wang, D D

    2016-01-01

    The aim was to meta-analyze randomized controlled trials of calcium plus vitamin D supplementation and fracture prevention. Meta-analysis showed a significant 15 % reduced risk of total fractures (summary relative risk estimate [SRRE], 0.85; 95 % confidence interval [CI], 0.73-0.98) and a 30 % reduced risk of hip fractures (SRRE, 0.70; 95 % CI, 0.56-0.87). Calcium plus vitamin D supplementation has been widely recommended to prevent osteoporosis and subsequent fractures; however, considerable controversy exists regarding the association of such supplementation and fracture risk. The aim was to conduct a meta-analysis of randomized controlled trials [RCTs] of calcium plus vitamin D supplementation and fracture prevention in adults. A PubMed literature search was conducted for the period from July 1, 2011 through July 31, 2015. RCTs reporting the effect of calcium plus vitamin D supplementation on fracture incidence were selected from English-language studies. Qualitative and quantitative information was extracted; random-effects meta-analyses were conducted to generate summary relative risk estimates (SRREs) for total and hip fractures. Statistical heterogeneity was assessed using Cochran's Q test and the I (2) statistic, and potential for publication bias was assessed. Of the citations retrieved, eight studies including 30,970 participants met criteria for inclusion in the primary analysis, reporting 195 hip fractures and 2231 total fractures. Meta-analysis of all studies showed that calcium plus vitamin D supplementation produced a statistically significant 15 % reduced risk of total fractures (SRRE, 0.85; 95 % confidence interval [CI], 0.73-0.98) and a 30 % reduced risk of hip fractures (SRRE, 0.70; 95 % CI, 0.56-0.87). Numerous sensitivity and subgroup analyses produced similar summary associations. A limitation is that this study utilized data from subgroup analysis of the Women's Health Initiative. This meta-analysis of RCTs supports the use of calcium plus

  17. Geometric Analysis of Vein Fracture Networks From the Awibengkok Core, Indonesia

    Science.gov (United States)

    Khatwa, A.; Bruhn, R. L.; Brown, S. R.

    2003-12-01

    Fracture network systems within rocks are important features for the transportation and remediation of hazardous waste, oil and gas production, geothermal energy extraction and the formation of vein fillings and ore deposits. A variety of methods, including computational and laboratory modeling have been employed to further understand the dynamic nature of fractures and fracture systems (e.g. Ebel and Brown, this session). To substantiate these studies, it is also necessary to analyze the characteristics and morphology of naturally occurring vein systems. The Awibengkok core from a geothermal system in West Java, Indonesia provided an excellent opportunity to study geometric and petrologic characteristics of vein systems in volcanic rock. Vein minerals included chlorite, calcite, quartz, zeolites and sulphides. To obtain geometric data on the veins, we employed a neural net image processing technique to analyze high-resolution digital photography of the veins. We trained a neural net processor to map the extent of the vein using RGB pixel training classes. The resulting classification image was then converted to a binary image file and processed through a MatLab program that we designed to calculate vein geometric statistics, including aperture and roughness. We also performed detailed petrographic and microscopic geometric analysis on the veins to determine the history of mineralization and fracturing. We found that multi-phase mineralization due to chemical dissolution and re-precipitation as well as mechanical fracturing was a common feature in many of the veins and that it had a significant role for interpreting vein tortuosity and history of permeability. We used our micro- and macro-scale observations to construct four hypothetical permeability models that compliment the numerical and laboratory modeled data reported by Ebel and Brown. In each model, permeability changes, and in most cases fluctuates, differently over time as the tortuosity and aperture of

  18. Application of Finite Element Method to Analyze the Influences of Process Parameters on the Cut Surface in Fine Blanking Processes by Using Clearance-Dependent Critical Fracture Criteria

    Directory of Open Access Journals (Sweden)

    Phyo Wai Myint

    2018-04-01

    Full Text Available The correct choice of process parameters is important in predicting the cut surface and obtaining a fully-fine sheared surface in the fine blanking process. The researchers used the value of the critical fracture criterion obtained by long duration experiments to predict the conditions of cut surfaces in the fine blanking process. In this study, the clearance-dependent critical ductile fracture criteria obtained by the Cockcroft-Latham and Oyane criteria were used to reduce the time and cost of experiments to obtain the value of the critical fracture criterion. The Finite Element Method (FEM was applied to fine blanking processes to study the influences of process parameters such as the initial compression, the punch and die corner radii and the shape and size of the V-ring indenter on the length of the sheared surface. The effects of stress triaxiality and punch diameters on the cut surface produced by the fine blanking process are also discussed. The verified process parameters and tool geometry for obtaining a fully-fine sheared SPCC surface are described. The results showed that the accurate and stable prediction of ductile fracture initiation can be achieved using the Oyane criterion.

  19. Finite element analysis of functionally graded bone plate at femur bone fracture site

    Science.gov (United States)

    Satapathy, Pravat Kumar; Sahoo, Bamadev; Panda, L. N.; Das, S.

    2018-03-01

    This paper focuses on the analysis of fractured Femur bone with functionally graded bone plate. The Femur bone is modeled by using the data from the CT (Computerized Tomography) scan and the material properties are assigned using Mimics software. The fracture fixation plate used here is composed of Functionally Graded Material (FGM). The functionally graded bone plate is considered to be composed of different layers of homogeneous materials. Finite element method approach is adopted for analysis. The volume fraction of the material is calculated by considering its variation along the thickness direction (z) according to a power law and the effective properties of the homogeneous layers are estimated. The model developed is validated by comparing numerical results available in the literature. Static analysis has been performed for the bone plate system by considering both axial compressive load and torsional load. The investigation shows that by introducing FG bone plate instead of titanium, the stress at the fracture site increases by 63 percentage and the deformation decreases by 15 percentage, especially when torsional load is taken into consideration. The present model yields better results in comparison with the commercially available bone plates.

  20. Fracture risk in patients with type 2 diabetes mellitus and possible risk factors: a systematic review and meta-analysis

    Directory of Open Access Journals (Sweden)

    Moayeri A

    2017-04-01

    Full Text Available Ardeshir Moayeri,1 Mahmoud Mohamadpour,2 Seyedeh Fatemeh Mousavi,3 Ehsan Shirzadpour,2 Safoura Mohamadpour,3 Mansour Amraei4 1Department of Anatomy, 2Department of Biochemistry, Faculty of Medicine, 3Department of Epidemiology, Prevention of Psychosocial Injuries Research Center, 4Department of Physiology, Faculty of Medicine, Ilam University of Medical Sciences, Ilam, Iran Aim: Patients with type 2 diabetes mellitus (T2DM have an increased risk of bone fractures. A variable increase in fracture risk has been reported depending on skeletal site, diabetes duration, study design, insulin use, and so on. The present meta-analysis aimed to investigate the association between T2DM with fracture risk and possible risk factors.Methods: Different databases including PubMed, Institute for Scientific Information, and Scopus were searched up to May 2016. All epidemiologic studies on the association between T2DM and fracture risk were included. The relevant data obtained from these papers were analyzed by a random effects model and publication bias was assessed by funnel plot. All analyses were done by R software (version 3.2.1 and STATA (version 11.1.Results: Thirty eligible studies were selected for the meta-analysis. We found a statistically significant positive association between T2DM and hip, vertebral, or foot fractures and no association between T2DM and wrist, proximal humerus, or ankle fractures. Overall, T2DM was associated with an increased risk of any fracture (summary relative risk =1.05, 95% confidence interval: 1.04, 1.06 and increased with age, duration of diabetes, and insulin therapy.Conclusion: Our findings strongly support an association between T2DM and increased risk of overall fracture. These findings emphasize the need for fracture prevention strategies in patients with diabetes. Keywords: diabetes mellitus, fractures, bone, osteoporosis, risk factors, meta-analysis

  1. Applications of ion scattering in surface analysis

    International Nuclear Information System (INIS)

    Armour, D.G.

    1981-01-01

    The study of ion scattering from surfaces has made an increasingly important contribution both to the development of highly surface specific analysis techniques and to the understanding of the atomic collision processes associated with ion bombardment of solid surfaces. From an analysis point of view, by appropriate choice of parameters such as ion energy and species, scattering geometry and target temperature, it is possible to study not only the composition of the surface layer but also the detailed atomic arrangement. The ion scattering technique is thus particularly useful for the study of surface compositional and structural changes caused by adsorption, thermal annealing or ion bombardment treatments of simple or composite materials. Ion bombardment induced desorption, damage or atomic mixing can also be effectively studied using scattering techniques. By reviewing the application of the technique to a variety of these technologically important surface investigations, it is possible to illustrate the way in which ion scattering has developed as the understanding of the underlying physics has improved. (author)

  2. On analogy between surface fracture energy and activaiton energy of bonding in solid phase

    International Nuclear Information System (INIS)

    Shatinsky, V.F.; Kopylov, V.I.

    1976-01-01

    This article makes an attempt on the basis of experimental data to compare the processes of failure and formation of a bond by comparing the energy consumptions going in one case or another into initial plastic deformation of a certain volume and the further interatomic interaction at the boundary (separation, formation of the bond). Two values characterizing the different processes - the unit failure energy γ and the activation energy for the formation of a bond Q - are compared. It has been established that the energy consumed for plastic deformation and adhesion interaction of atoms on the surface of microprojections and providing the formation of a bond in the solid-phase condition is close to the specific failure energy. The equality of energies consumed for the formation of a bond and failure allows to make use of any of those characteristics to calculate parameters of processes of the formation of a bond and failure. It seems to be convenient in the analysis of the failure process at a temperature when the ductility is high and methodically, the crack propagation is hard to investigate, in particular to estimate the volume of the preliminary failure zone. Having determined γ from the contact interaction data, the strength characteristics can be evaluated. (author)

  3. Biomechanical analysis of the fixation systems for anterior column and posterior hemi-transverse acetabular fractures.

    Science.gov (United States)

    Lei, Jianyin; Dong, Pengfei; Li, Zhiqiang; Zhu, Feng; Wang, Zhihua; Cai, Xianhua

    2017-05-01

    The aim of this study was to evaluate the biomechanical properties of common fixation systems for complex acetabular fractures. A finite element (FE) pelvic model with anterior column and posterior hemi-transverse acetabular fractures was created. Three common fixation systems were used to fix the posterior wall acetabular fractures: 1. Anterior column plate combined with posterior column screws (group I), 2. Anterior column plate combined with quadrilateral area screws (group II) and 3. Double-column plates (group III). And 600 N, representing the body weight, was loaded on the upper surface of the sacrum to simulate the double-limb stance. The amounts of total and relative displacements were compared between the groups. The total amount of displacement was 2.76 mm in group II, 2.81 mm in group III, and 2.83 mm in group I. The amount of relative displacement was 0.0078 mm in group II, 0.0093 mm in group III and 0.014 mm in group I. Our results suggested that all fixation systems enhance biomechanical stability significantly. Anterior column plate combined with quadrilateral area screws has quite comparable results to double column plates, they were superior to anterior column plate combined with posterior screws. Copyright © 2017 Turkish Association of Orthopaedics and Traumatology. Production and hosting by Elsevier B.V. All rights reserved.

  4. Analysis of the behavior of radionuclides migration in fractured medium in different types of rocks matrices

    International Nuclear Information System (INIS)

    Sá, Ludimila Silva Salles de; Silveira, Cláudia Siqueira da; Lima, Zelmo Rodrigues de

    2017-01-01

    In management of radioactive wastes, the current trend is to dispose the radioactive waste for long life and high activity in permanent repositories of depth, geologically stable and low permeability. Thus, it is relevant to analyze the groundwater movement process, because the mechanism by which the radionuclides in a repository with fractures could return to the surface would be through the groundwater circulation system. A common problem encountered is the modeling of the migration of radionuclides in a fractured medium. The objective of this work is to evaluate the behavior of the migration of radionuclides in two types of rock matrix, considering the following properties: volumetric density, porosity, distribution coefficient and molecular diffusion coefficient. The physical system adopted consists of the matrix rock containing a discrete fracture in a porous medium saturated with water. The partial differential equations that describe the radionuclide movement were discretized by finite differences, and the Implicit Euler method was adopted. While for the convective term the numerical scheme of progressive differences was used

  5. Short frontal plane fractures involving the dorsoproximal articular surface of the proximal phalanx: Description of the injury and a technique for repair.

    Science.gov (United States)

    Wright, I M; Minshall, G J

    2018-01-01

    Chip fractures of the dorsoproximal articular margin of the proximal phalanx are common injuries in racehorses. Large fractures can extend distal to the joint capsule insertion and have been described as dorsal frontal fractures. To report the location and morphology of short frontal plane fractures involving the dorsoproximal articular surface of the proximal phalanx and describe a technique for repair under arthroscopic and radiographic guidance. Single centre retrospective case study. Case records of horses with frontal plane fractures restricted to the dorsoproximal epiphysis and metaphysis of the proximal phalanx referred to Newmarket Equine Hospital were retrieved, images reviewed and lesion morphology described. A technique for repair and the results obtained are reported. A total of 22 fractures in 21 horses commencing at the proximal articular surface exited the dorsal cortex of the proximal phalanx distal to the metacarpophalangeal/metatarsophalangeal joint capsule in 17 hind- and five forelimbs. All were in Thoroughbred racehorses. In 16 cases these were acute racing or training injuries; 20 fractures were medial, one lateral and one was midline. All were repaired with a single lag screw using arthroscopic and radiographically determined landmarks. A total of 16 horses raced after surgery with performance data similar to their preinjury levels. The study demonstrates substantial morphological similarities between individual lesions supporting a common pathophysiology, but does not identify precise causation. There are no cases managed differently that might permit assessment of the comparative efficacy of the treatment described. Short frontal plane fractures involving the dorsoproximal margin of the proximal phalanx that exit the bone distal to the metacarpophalangeal/metatarsophalangeal joint capsule have substantial morphological similarities, are amenable to minimally invasive repair and carry a good prognosis for return to training and racing.

  6. Qualitative assessment of bone density at the distal articulating surface of the third metacarpal in Thoroughbred racehorses with and without condylar fracture.

    Science.gov (United States)

    Loughridge, A B; Hess, A M; Parkin, T D; Kawcak, C E

    2017-03-01

    Changes in subchondral bone density, induced by the repetitive cyclical loading of exercise, may potentiate fatigue damage and the risk of fracture. To use computed tomography (CT) to characterise bone density patterns at the articular surface of the third metacarpal bone in racehorses with and without lateral condylar fractures. Case control METHODS: Computed tomographic images of the distal articulating surface of the third metacarpal bone were obtained from Thoroughbred racehorses subjected to euthanasia in the UK. Third metacarpal bones were divided into 3 groups based on lateral condyle status; fractured (FX, n = 42), nonfractured contralateral condyle (NFX, n = 42) and control condyles from horses subjected to euthanasia for reasons unrelated to the third metacarpal bone (control, n = 94). Colour CT images were generated whereby each colour represented a range of pixel values and thus a relative range of bone density. A density value was calculated qualitatively by estimating the percentage of each colour within a specific region. Subchondral bone density was assessed in 6 regions from dorsal to palmar and 1 mm medial and lateral to the centre of the lateral parasagittal groove in NFX and control condyles and 1 mm medial and lateral to the fracture in FX condyles. Bone density was significantly higher in the FX and NFX condyles compared with control condyles for all 6 regions. A significantly higher bone density was observed in FX condyles relative to NFX condyles in the lateral middle and lateral palmar regions. Fractured condyles had increased heterogeneity in density among the 6 regions of interest compared with control and NFX condyles. Adjacent to the fracture, a focal increase in bone density and increased heterogeneity of density were characteristic of limbs with lateral condylar fractures compared with control and NFX condyles. These differences may represent pathological changes in bone density that increase the risk for lateral condylar fractures in

  7. Assessment of bone quality in the isolated femoral head for intracapsular fractures of the femoral head. Analysis of bone architecture using micro-CT and pQCT, and comparison with extracapsular fractures

    International Nuclear Information System (INIS)

    Sando, Masaru

    2003-01-01

    Block sections were prepared from the five locations, central portion, superior portion, inferior portion, anterior portion, and posterior portion, of the region around the fracture of the femoral head isolated from 21 patients (16 patients with intracapsular fracture, 5 patients with extracapsular fracture). Cancellous bone microstructure, cortical bone thickness, and bone density were evaluated and analyzed for differences in the mechanism from which intracapsular versus extracapsular fracture and fragility developed. The method of evaluating the bone architecture differed from conventional bone histomorphometry of hard tissues and involved non-invasive micro-CT measurements, while the bone density was measured by peripheral quantitative computed topography (pQCT). The results indicate that in comparison to patients with extracapsular fractures, patients with intracapsular fractures showed significant decreases in the trabecular thickness of superior and posterior portions in the cancellous bone. The cortical bone thickness was significantly decreased in the superior portion. Bone density was significantly decreased in the superior portion, while in the extracapsular fracture group density tended to be lower in the inferior, anterior, and posterior portions, although this was not statistically significant. Although there have been previous studies on the bone quality of the femoral head isolated from intracapsular fracture of the femoral head, most reports are of two-dimensional analysis of coronal sections. As far as we are aware, there have been no previous reports comparing individual locations to extracapsular fractures. In view of the various reports that bone density is lower in the extracapsular fracture compared to the intracapsular fracture, we speculate that extracapsular fracture results from the effects of external forces on decreased bone density, while in the intracapsular fracture type, thinning of the superior portion of the cortical bone creates

  8. Surface and interface analysis of photovoltaic devices

    International Nuclear Information System (INIS)

    Kazmerski, L.L.

    1983-01-01

    Interface chemistry can control the performance and operational lifetime of solar cells, especially thin-film, polycrystalline devices. The composition and elemental integrity of device surfaces, internal junctions, layer and defect interfces can be related to and dominate the electroptical characteristics of the materials/ devices. This paper examines the compositional properties of external and internal surfaces in polycrystaline solar cells, utilizing high-resolution, complementary surface analysis techniques. The electronic properties of these same regions are evaluated using microelectrical characterization methods. Cell performance, in turn, is explained in terms of these relation-ships. Specifically, two solar cell types are used as examples: (1) the polycrystalline Si homojunction and (2) the (Cd Zn)S/CuInSe 2 heterojunction. Throughout these investigations of photovoltaic devices, the limitations and strengths of the surface and electrical microanalyses techniques are emphasized and discussed. (Author) [pt

  9. Edge Fracture in Complex Fluids.

    Science.gov (United States)

    Hemingway, Ewan J; Kusumaatmaja, Halim; Fielding, Suzanne M

    2017-07-14

    We study theoretically the edge fracture instability in sheared complex fluids, by means of linear stability analysis and direct nonlinear simulations. We derive an exact analytical expression for the onset of edge fracture in terms of the shear-rate derivative of the fluid's second normal stress difference, the shear-rate derivative of the shear stress, the jump in shear stress across the interface between the fluid and the outside medium (usually air), the surface tension of that interface, and the rheometer gap size. We provide a full mechanistic understanding of the edge fracture instability, carefully validated against our simulations. These findings, which are robust with respect to choice of rheological constitutive model, also suggest a possible route to mitigating edge fracture, potentially allowing experimentalists to achieve and accurately measure flows stronger than hitherto possible.

  10. Fracture analysis of Ag nanobrazing of NiTi to Ti alloy

    Directory of Open Access Journals (Sweden)

    L. Quintino

    2013-09-01

    Full Text Available Dissimilar joining of shape memory alloys to Ti alloys has long been attempted by several research groups due to the foreseen potential industrial applications. However, the very dissimilar thermo-physical properties of both materials place several difficulties. Brazing can be a solution since the base materials are subjected to a less sharp thermal cycle. In the present study brazed overlap joints of 1 mm thick plates of equiatomic NiTi and Ti6Al4V were produced using nano silver based filler materials. Surfaces were analyzed to assess the type of fracture and the capability of achieving bonding and involved mechanisms are discussed.

  11. Fracture analysis of Ag nanobrazing of NiTi to Ti alloy

    Energy Technology Data Exchange (ETDEWEB)

    Quintino, L., E-mail: lquirino@ist.utl.pt [Universidade Tecnica de Lisboa (IST/UTL) (Portugal). Instituto Superior Tecnico. Dept. de Engenharia Mecanica; Liu, L., E-mail: ray.plasma@gmail.com [Tsinghua Univ., Beijing (China). Dept. of Mechanical Engineering; Hu, A.; Zhou, Y., E-mail: anming.hu@uwaterloo.ca, E-mail: nzhou@uwaterloo.ca [University of Waterloo, Ontario (Canada). Dept. of Mechanical Engineering; Miranda, R.M., E-mail: rmiranda@fct.unl.pt [Universidade Nova de Lisboa (UNIDEMI), Caparica (Portugal). Dept. de Engenharia Mecanica e Industrial

    2013-07-15

    Dissimilar joining of shape memory alloys to Ti alloys has long been attempted by several research groups due to the foreseen potential industrial applications. However, the very dissimilar thermo-physical properties of both materials place several difficulties. Brazing can be a solution since the base materials are subjected to a less sharp thermal cycle. In the present study brazed overlap joints of 1 mm thick plates of equiatomic Ni Ti and Ti6Al4V were produced using nano silver based filler materials. Surfaces were analyzed to asses the type of fracture and the capability of achieving bonding and involved mechanisms are discussed. (author)

  12. Level crossing analysis of growing surfaces

    International Nuclear Information System (INIS)

    Shahbazi, F; Sobhanian, S; Tabar, M Reza Rahimi; Khorram, S; Frootan, G R; Zahed, H

    2003-01-01

    We investigate the average frequency of positive slope ν + α , crossing the height α = h - h-bar in the surface growing processes. The exact level crossing analysis of the random deposition model and the Kardar-Parisi-Zhang equation in the strong coupling limit before creation of singularities is given

  13. Can a semi-automated surface matching and principal axis-based algorithm accurately quantify femoral shaft fracture alignment in six degrees of freedom?

    Science.gov (United States)

    Crookshank, Meghan C; Beek, Maarten; Singh, Devin; Schemitsch, Emil H; Whyne, Cari M

    2013-07-01

    Accurate alignment of femoral shaft fractures treated with intramedullary nailing remains a challenge for orthopaedic surgeons. The aim of this study is to develop and validate a cone-beam CT-based, semi-automated algorithm to quantify the malalignment in six degrees of freedom (6DOF) using a surface matching and principal axes-based approach. Complex comminuted diaphyseal fractures were created in nine cadaveric femora and cone-beam CT images were acquired (27 cases total). Scans were cropped and segmented using intensity-based thresholding, producing superior, inferior and comminution volumes. Cylinders were fit to estimate the long axes of the superior and inferior fragments. The angle and distance between the two cylindrical axes were calculated to determine flexion/extension and varus/valgus angulation and medial/lateral and anterior/posterior translations, respectively. Both surfaces were unwrapped about the cylindrical axes. Three methods of matching the unwrapped surface for determination of periaxial rotation were compared based on minimizing the distance between features. The calculated corrections were compared to the input malalignment conditions. All 6DOF were calculated to within current clinical tolerances for all but two cases. This algorithm yielded accurate quantification of malalignment of femoral shaft fractures for fracture gaps up to 60 mm, based on a single CBCT image of the fractured limb. Copyright © 2012 IPEM. Published by Elsevier Ltd. All rights reserved.

  14. Injuries of the trochanteric region: can analysis of radiographic indices help in prediction of recurrent osteoporotic hip fractures?

    Science.gov (United States)

    Pellegrini, Andrea; Tacci, Fabrizio; Leigheb, Massimiliano; Costantino, Cosimo; Pedrazzini, Alessio; Pedrazzi, Giuseppe; Vaienti, Enrico; Ceccarelli, Francesco; Pogliacomi, Francesco

    2017-10-18

    In a context of bone fragility, primitive and subsequent fractures are a growing problem in the industrialized countries where the mean age of the population is constantly increasing. Among the various factors that favor a fragility fracture, the most important is osteoporosis, a pathology that can be prevented through diagnostic screenings and treated by pharmacological and rehabilitative therapies. The aim of this study is to identify the subjects who are likely to have a higher risk of subsequent fractures of the trochanteric region through a retrospective radiographic evaluation of patients affected by low-energy trochanteric fractures and operated by intramedullary fixation between June 2013 and June 2015, so they can be targeted for prevention interventions. Three hundred and sixty-one patients yet alive were analyzed 2 years after surgery. Fifty-one (group 1), characterized by another contralateral trochanteric femoral fracture, were included. All subjects were retrospectively examined with the analysis of contralateral femur X-ray performed at the time of initial trauma in order to detect a condition of bone fragility and a predisposition to fractures by evaluating three radiographic indices (Singh index, Dorr's classification and Cortical Thickness Index). Patients of group 1 were compared to the other 310 patients (group 2) affected by isolated trochanteric fracture. Group 1 had all radiographic indices worse than group 2. The results observed suggest that orthopedists can use radiographic indices, in particular Cortical Thickness Index, as a valuable, simple and inexpensive screening tool for prevention of recurrent osteoporotic fractures.

  15. Aespoe Hard Rock Laboratory. Analysis of fracture networks based on the integration of structural and hydrogeological observations on different scales

    Energy Technology Data Exchange (ETDEWEB)

    Bossart, P. [Geotechnical Inst. Ltd., Bern (Switzerland); Hermanson, Jan [Golder Associates, Stockholm (Sweden); Mazurek, M. [Univ. of Bern (Switzerland)

    2001-05-01

    Fracture networks at Aespoe have been studied for several rock types exhibiting different degrees of ductile and brittle deformation, as well as on different scales. Mesoscopic fault systems have been characterised and classified in an earlier report, this report focuses mainly on fracture networks derived on smaller scales, but also includes mesoscopic and larger scales. The TRUE-1 block has been selected for detailed structural analysis on a small scale due to the high density of relevant information. In addition to the data obtained from core materials, structural maps, BIP data and the results of hydro tests were synthesised to derive a conceptual structural model. The approach used to derive this conceptual model is based on the integration of deterministic structural evidence, probabilistic information and both upscaling and downscaling of observations and concepts derived on different scales. Twelve fracture networks mapped at different sites and scales and exhibiting various styles of tectonic deformation were analysed for fractal properties and structural and hydraulic interconnectedness. It was shown that these analysed fracture networks are not self-similar. An important result is the structural and hydraulic interconnectedness of fracture networks on all scales in the Aespoe rocks, which is further corroborated by geochemical evidence. Due to the structural and hydraulic interconnectedness of fracture systems on all scales at Aespoe, contaminants from waste canisters placed in tectonically low deformation environments would be transported - after having passed through the engineered barriers -from low-permeability fractures towards higher permeability fractures and may thus eventually reach high-permeability features.

  16. Aespoe Hard Rock Laboratory. Analysis of fracture networks based on the integration of structural and hydrogeological observations on different scales

    International Nuclear Information System (INIS)

    Bossart, P.; Hermanson, Jan; Mazurek, M.

    2001-05-01

    Fracture networks at Aespoe have been studied for several rock types exhibiting different degrees of ductile and brittle deformation, as well as on different scales. Mesoscopic fault systems have been characterised and classified in an earlier report, this report focuses mainly on fracture networks derived on smaller scales, but also includes mesoscopic and larger scales. The TRUE-1 block has been selected for detailed structural analysis on a small scale due to the high density of relevant information. In addition to the data obtained from core materials, structural maps, BIP data and the results of hydro tests were synthesised to derive a conceptual structural model. The approach used to derive this conceptual model is based on the integration of deterministic structural evidence, probabilistic information and both upscaling and downscaling of observations and concepts derived on different scales. Twelve fracture networks mapped at different sites and scales and exhibiting various styles of tectonic deformation were analysed for fractal properties and structural and hydraulic interconnectedness. It was shown that these analysed fracture networks are not self-similar. An important result is the structural and hydraulic interconnectedness of fracture networks on all scales in the Aespoe rocks, which is further corroborated by geochemical evidence. Due to the structural and hydraulic interconnectedness of fracture systems on all scales at Aespoe, contaminants from waste canisters placed in tectonically low deformation environments would be transported - after having passed through the engineered barriers -from low-permeability fractures towards higher permeability fractures and may thus eventually reach high-permeability features

  17. Process comparison for fracture-induced formation of surface structures on polymer films

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yueh-Ying [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Yang, Fuqian [Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506 (United States); Chen, Chia-Chieh [Institute of Nuclear Energy Research, Longtan, Taoyuan 32546, Taiwan (China); Lee, Sanboh, E-mail: sblee@mx.nthu.edu.tw [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China)

    2014-01-01

    Using three different splitting approaches such as point-load splitting, tension-splitting and peeling–splitting, different surface ripples were produced on poly(methyl methacrylate) (PMMA)-based polymer films. Independent of the splitting approaches, the spatial wavelength of the surface structures is a linear function of the film thickness with the approximately same differential ratio of the spatial wavelength to the film thickness. The apparent surface residual stress was calculated from the thickness dependence of the spatial frequency, and the magnitude of the apparent surface stress increased with the increase of the film thickness. After exposing the aged PMMA-based photoresist at liquid state to gamma-irradiation, the effects of aging and the gamma-irradiation were investigated on the splitting-induced formation of surface structures. For the peeling–splitting process, the differential ratio of the spatial wavelength to the film thickness for the aged samples is larger than that for non-aged samples. The point-load splitting could not produce any surface pattern on the gamma-irradiated films. None of the splitting approaches could form surface structures for polymer films exposed to irradiation of high dose. Both the spatial wavelength and the apparent surface stress increased with the film thickness for the irradiated polymer films. - Highlights: • Using splitting processes, surface ripples were formed on polymer films. • The surface ripples were induced by compressively apparent surface stress. • The spatial wavelength of the ripples is a linear function of the film thickness. • The spatial wavelength of the ripples is affected by gamma-ray irradiation. • The spatial wavelength of the ripples is affected by aging.

  18. Analysis of the flow property of aluminum alloy AA6016 based on the fracture morphology using the hydroforming technology

    Science.gov (United States)

    Lang, Lihui; Zhang, Quanda; Sun, Zhiying; Wang, Yao

    2017-09-01

    In this paper, the hydraulic bulging experiments were respectively carried out using AA6016-T4 aluminum alloy and AA6016-O aluminum alloy, and the deformation properties and fracture mechanism of aluminum alloy under the conditions of thermal and hydraulic were analyzed. Firstly, the aluminum alloy AA6016 was dealt with two kinds of heat treatment systems such as solid solution heat treatment adding natural ageing and full annealing, then the aluminum alloy such as AA6016-T4 and AA6016-O were obtained. In the same working environment, the two kinds of materials were used in the process of hydraulic bulging experiments, according to the observation and measurement of the deformation sizes of grid circles and material thicknesses near the fracture region, the flow properties and development trend of fracture defect of the materials were analyzed comprehensively from the perspective of qualitative analysis and quantitative analysis; Secondly, the two kinds of materials were sampled in different regions of the fracture area and the microstructure morphology of the fracture was observed by the scanning electron microscope (SEM). The influence laws of the heat treatment systems on the fracture defect of the aluminum alloy under the condition of the liquid pressure were studied preliminarily by observing the distribution characteristics of the fracture microstructure morphology of dimple. At the same time, the experimental research on the ordinary stamping forming process of AA6016-O was carried out and the influence law of different forming process on the fracture defect of the aluminum alloy material was studied by observing the distribution of the fracture microstructure morphology; Finally, the development process of the fracture defect of aluminum alloy sheet was described theoretically from the view of the stress state.

  19. Sensitivity analysis of a coupled hydro-mechanical paleo-climate model of density-dependent groundwater flow in discretely fractured crystalline rock

    International Nuclear Information System (INIS)

    Normani, S.D.; Sykes, J.F.

    2011-01-01

    A high resolution three-dimensional sub-regional scale (104 km 2 ) density-dependent, discretely fractured groundwater flow model with hydro-mechanical coupling and pseudo-permafrost was developed from a larger 5734 km 2 regional-scale groundwater flow model of a Canadian Shield setting. The objective of the work is to determine the sensitivity of modelled groundwater system evolution to the hydro-mechanical parameters. The discrete fracture dual continuum numerical model FRAC3DVS-OPG was used for all simulations. A discrete fracture network model delineated from surface features was superimposed onto an approximate 790 000 element domain mesh with approximately 850 000 nodes. Orthogonal fracture faces (between adjacent finite element grid blocks) were used to best represent the irregular discrete fracture zone network. Interconnectivity of the permeable fracture zones is an important pathway for the possible migration and subsequent reduction in groundwater and contaminant residence times. The crystalline rock matrix between these structural discontinuities was assigned mechanical and flow properties characteristic of those reported for the Canadian Shield. The variation of total dissolved solids with depth was assigned using literature data for the Canadian Shield. Performance measures for the sensitivity analysis include equivalent freshwater heads, environmental heads, linear velocities, and depth of penetration by conservative non-decaying tracers released at the surface. A 121 000 year North American continental scale paleo-climate simulation was applied to the domain with ice-sheet histories estimated by the University of Toronto Glacial Systems Model (UofT GSM). Hydro-mechanical coupling between the rock matrix and the pore fluid, due to the ice sheet normal stress, was included in the simulations. The flow model included the influence of vertical strain and assumed that areal loads were homogeneous. Permafrost depth was applied as a permeability reduction

  20. Repository surface design site layout analysis

    International Nuclear Information System (INIS)

    Montalvo, H.R.

    1998-01-01

    The purpose of this analysis is to establish the arrangement of the Yucca Mountain Repository surface facilities and features near the North Portal. The analysis updates and expands the North Portal area site layout concept presented in the ACD, including changes to reflect the resizing of the Waste Handling Building (WHB), Waste Treatment Building (WTB), Carrier Preparation Building (CPB), and site parking areas; the addition of the Carrier Washdown Buildings (CWBs); the elimination of the Cask Maintenance Facility (CMF); and the development of a concept for site grading and flood control. The analysis also establishes the layout of the surface features (e.g., roads and utilities) that connect all the repository surface areas (North Portal Operations Area, South Portal Development Operations Area, Emplacement Shaft Surface Operations Area, and Development Shaft Surface Operations Area) and locates an area for a potential lag storage facility. Details of South Portal and shaft layouts will be covered in separate design analyses. The objective of this analysis is to provide a suitable level of design for the Viability Assessment (VA). The analysis was revised to incorporate additional material developed since the issuance of Revision 01. This material includes safeguards and security input, utility system input (size and location of fire water tanks and pump houses, potable water and sanitary sewage rates, size of wastewater evaporation pond, size and location of the utility building, size of the bulk fuel storage tank, and size and location of other exterior process equipment), main electrical substation information, redundancy of water supply and storage for the fire support system, and additional information on the storm water retention pond

  1. The application of probabilistic fracture analysis to residual life evaluation of embrittled reactor vessels

    International Nuclear Information System (INIS)

    Dickson, T.L.; Simonen, F.A.

    1992-01-01

    Probabilistic fracture mechanics analysis is a major element of the comprehensive probabilistic methodology on which current NRC regulatory requirements for pressurized water reactor vessel integrity evaluation are based. Computer codes such as OCA-P and VISA-11 perform probabilistic fracture analyses to estimate the increase in vessel failure probability that occurs as the vessel material accumulates radiation damage over the operating life of the vessel. The results of such analyses, when compared with limits of acceptable failure probabilities, provide an estimation of the residual life of a vessel. Such codes can be applied to evaluate the potential benefits of plant-specific mitigating actions designed to reduce the probability of failure of a reactor vessel

  2. Fracture Analysis of CNG High Pressure Container using Fractography and Measurement of Property

    Directory of Open Access Journals (Sweden)

    Kim Eui-Soo

    2017-01-01

    Full Text Available Bursting accidents of pressure containers due to design and manufacturing defects are frequently occurring. Due to high-pressure gas or harmful substances, when this vessel is fractured, it can lead to catastrophic disasters. Especially, in the event of bursting accident of composite pressure vessel for CNG bus, many unspecified people can be damaged. Most of the accidents were caused by problems in the manufacturing process. The manufacturing process for TYPE2 pressure vessel is very complicated such as three drawing processes, two ironing processes and one spinning process. In the middle of process, various heat treatments are performed for imparting toughness and removing residual stresses. It should cause a serious problem such as bursting and fragmentation of the pressure container due to defects of this process. In this research, the fracture cause of CNG vessel is evaluated through fractography and measuring material property using IIT and analysis of chemical composition.

  3. Signal-to-noise ratio application to seismic marker analysis and fracture detection

    Science.gov (United States)

    Xu, Hui-Qun; Gui, Zhi-Xian

    2014-03-01

    Seismic data with high signal-to-noise ratios (SNRs) are useful in reservoir exploration. To obtain high SNR seismic data, significant effort is required to achieve noise attenuation in seismic data processing, which is costly in materials, and human and financial resources. We introduce a method for improving the SNR of seismic data. The SNR is calculated by using the frequency domain method. Furthermore, we optimize and discuss the critical parameters and calculation procedure. We applied the proposed method on real data and found that the SNR is high in the seismic marker and low in the fracture zone. Consequently, this can be used to extract detailed information about fracture zones that are inferred by structural analysis but not observed in conventional seismic data.

  4. The application of ductile-fracture analysis to predictions of pressure-tube failure

    International Nuclear Information System (INIS)

    Simpson, L.A.

    1981-08-01

    Progress during the past six years towards establishing a method for predicting critical crack length in a reactor pressure tube, based on data from tests on small fracture-mechanics specimens, is reviewed. The disadvantages of relying on data from burst tests alone are described along with the benefits of a small-specimen method. It is clear from the work reviewed that only an approach that can account for the ability of the presssure tube material to increase its crack-growth resistance during stable crack extension is suitable for the prediction of critical crack length. A method that utilizes crack-growth resistance curves based on crack-opening displacement, or the J integral, is described, along with a large body of experimental data. It is concluded that the resistance curve approach provides a viable method for the analysis of fracture in pressure tubes that can greatly improve our understanding of the material's behaviour

  5. The application of probabilistic fracture analysis to residual life evaluation of embrittled reactor vessels

    International Nuclear Information System (INIS)

    Dickson, T.L.; Simonen, F.A.

    1992-01-01

    Probabilistic fracture mechanics analysis is a major element of comprehensive probabilistic methodology on which current NRC regulatory requirements for pressurized water reactor vessel integrity evaluation are based. Computer codes such as OCA-P and VISA-II perform probabilistic fracture analyses to estimate the increase in vessel failure probability that occurs as the vessel material accumulates radiation damage over the operating life of the vessel. The results of such analyses, when compared with limits of acceptable failure probabilities, provide an estimation of the residual life of a vessel. Such codes can be applied to evaluate the potential benefits of plant-specific mitigating actions designed to reduce the probability of failure of a reactor vessel. 10 refs

  6. Concentration and spectroscopic characteristics of DOM in surface runoff and fracture flow in a cropland plot of a loamy soil.

    Science.gov (United States)

    Xian, Qingsong; Li, Penghui; Liu, Chen; Cui, Junfang; Guan, Zhuo; Tang, Xiangyu

    2018-05-01

    Being crucial for predicting the impact of source inputs on a watershed in rainfall events, an understanding of the dynamics and characteristics of dissolved organic matter (DOM) export from the soil under particular land use types, particularly those associated with underground flows is still largely lacking. A field study was carried out using a 1500m 2 slope farmland plot in the hilly area of Sichuan Basin, Southwest China. The discharge of surface runoff and fracture flow was recorded and samples were collected in four representative rainfall events. For DOM characterization, concentration of dissolved organic carbon (DOC) and absorbance/excitation-emission matrix (EEM) fluorescence were analyzed. Soil water potential was also determined using tensiometers for understanding the runoff generation mechanisms. The DOC values for both surface and fracture flow showed significant responses to rainfall, with hydrological path being the primary factor in determining DOM dynamics. EEM-PARAFAC analyses indicated that the soil DOM mainly consisted of two terrestrial humic-like components with peaks located at Ex/Em 270(380)/480nm (C1) and 250(320)/410nm (C2), respectively. Concentrations of these components also responded strongly to rainfall, fluctuating in good agreement with the corresponding DOCs. Although there was no change in the presence of the components themselves, their relative distributions varied during precipitation, with the C1/C2 ratio increasing with the proportion of soil pre-event water. As the dynamic changes of soil DOM characteristics can be successfully captured using spectroscopic techniques, they may serve as a tracer for understanding hydrological paths based on their potential correlations with water source differences during rains. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. SURFACE TEXTURE ANALYSIS FOR FUNCTIONALITY CONTROL

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo; Andreasen, Jan Lasson; Tosello, Guido

    This document is used in connection with three exercises of 3 hours duration as a part of the course VISION ONLINE – One week course on Precision & Nanometrology. The exercises concern surface texture analysis for functionality control, in connection with three different case stories. This docume...... contains a short description of each case story, 3-D roughness parameters analysis and relation with the product’s functionality.......This document is used in connection with three exercises of 3 hours duration as a part of the course VISION ONLINE – One week course on Precision & Nanometrology. The exercises concern surface texture analysis for functionality control, in connection with three different case stories. This document...

  8. Postoperative prophylactic antibiotics for facial fractures: A systematic review and meta-analysis.

    Science.gov (United States)

    Habib, Andy M; Wong, Alexander D; Schreiner, Geoffrey C; Satti, Komal F; Riblet, Natalie B; Johnson, Heather A; Ossoff, Jacob P

    2018-05-14

    Perioperative antibiotic prophylaxis in patients undergoing surgery for maxillofacial fractures is standard practice. However, the use of postoperative antibiotic prophylaxis remains controversial. This systematic review and meta-analysis sought to evaluate the effect of postoperative antibiotic therapy on the incidence of surgical site infection (SSI) in patients with maxillofacial fractures. MEDLINE, Embase, and the Cochrane Library were searched from inception through October 2017. Randomized controlled trials (RCTs) and cohort studies evaluating the efficacy of pre-, peri-, and postoperative antibiotic prophylaxis in preventing SSI in maxillofacial fractures were included. Data were extracted from studies using a standardized data collection form, with two reviewers independently performing extraction and quality assessment for each study. Risk ratios (RRs) for SSI were pooled using a random-effects model. Among 2,150 potentially eligible citations, 13 studies met inclusion criteria and provided data to be included in a meta-analysis. The addition of postoperative antibiotic prophylaxis to a standard preoperative and/or perioperative antibiotic regimen showed no significant difference in the risk of SSI (RR = 1.11 [95% CI: 0.86-1.44], P > .1). There were also no differences in the risk of SSI when restricting the analysis to mandibular fractures (eight studies, RR = 1.22 [95% CI: 0.92-1.62]) or open surgical techniques (eight studies, RR = 1.02 [95% CI: 0.62-1.67]). A sensitivity analysis did not find any significant differences in risk when restricting to RCTs (seven trials, RR = 1.00 [95% CI: 0.61-1.67]) or cohort studies (six studies, RR = 1.21 [95% CI: 0.89-1.63]). Our findings, along with the available evidence, does not support the routine use of postoperative antibiotic prophylaxis in patients with maxillofacial fractures. Avoiding the unnecessary use of antibiotic therapy in the postoperative period could have important

  9. A Study on the Fatigue-Fractured Surface of Normalized SS41 Steel and M.E.F. Dual Phase Steel by an X-ray Diffraction Technique

    International Nuclear Information System (INIS)

    Oh, Sae Wook; Park, Young Chul; Park, Soo Young; Kim, Deug Jin; Hue, Sun Chul

    1996-01-01

    This study verified the relationship between fracture mechanics parameters and X-ray parameters for normalized SS41 steel with homogeneous crystal structure and M.E.F. dual phase steel(martensite encapsulated islands of ferrite). The fatigue crack propagation test were carried out and X-ray diffraction technique was applied to fatigue fractured surface. The change in X-ray parameters(residual stress, half-value breadth) according to the depth of fatigue fractured surface were investigated. The depth of maximum plastic zone, W y , were determined on the basis of the distribution of the half-value breadth for normalized SS41 steel and that of the residual stress for M.E.F. dual phase steel. K max could be estimated by the measurement of W y

  10. Surface analysis with STM and AFM

    CERN Document Server

    Magonov, Sergi N

    1996-01-01

    Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) are powerful tools for surface examination. In the past, many STM and AFM studies led to erroneous conclusions due to lack of proper theoretical considerations and of an understanding of how image patterns are affected by measurement conditions. For this book, two world experts, one on theoretical analysis and the other on experimental characterization, have joined forces to bring together essential components of STM and AFM studies: The practical aspects of STM, the image simulation by surface electron density plot calculat

  11. Computational methods for fracture analysis of heavy-section steel technology (HSST) pressure vessel experiments

    International Nuclear Information System (INIS)

    Bass, B.R.; Bryan, R.H.; Bryson, J.W.; Merkle, J.G.

    1985-01-01

    This paper summarizes the capabilities and applications of the general-purpose and special-purpose computer programs that have been developed at ORNL for use in fracture mechanics analyses of HSST pressure vessel experiments. Emphasis is placed on the OCA/USA code, which is designed for analysis of pressurized-thermal-shock (PTS) conditions, and on the ORMGEN/ADINA/ORVIRT system which is used for more general analysis. Fundamental features of these programs are discussed, along wih applications to pressure vessel experiments. (orig./HP)

  12. Comparison of Ultrasonography and Radiography in Detection of Thoracic Bone Fractures; a Systematic Review and Meta-Analysis.

    Science.gov (United States)

    Yousefifard, Mahmoud; Baikpour, Masoud; Ghelichkhani, Parisa; Asady, Hadi; Darafarin, Abolfazl; Amini Esfahani, Mohammad Reza; Hosseini, Mostafa; Yaseri, Mehdi; Safari, Saeed

    2016-01-01

    The potential benefit of ultrasonography for detection of thoracic bone fractures has been proven in various surveys but no comprehensive conclusion has been drawn yet; therefore, the present study aimed to conduct a thorough meta-analytic systematic review on this subject. Two reviewers independently carried out a comprehensive systematic search in Medline, EMBASE, ISI Web of Knowledge, Scopus, Cochrane Library, and ProQuest databases. Data were summarized as true positive, false positive, true negative and false negative and were analyzed via STATA 11.0 software using a mixed-effects binary regression model. Sources of heterogeneity were further assessed through subgroup analysis. Data on 1667 patients (807 subjects with and 860 cases without thoracic fractures), whose age ranged from 0 to 92 years, were extracted from 17 surveys. Pooled sensitivity and specificity of ultrasonography in detection of thoracic bone fractures were 0.97 (95% CI: 0.90-0.99; I2= 88.88, prib fractures, compared to fractures of sternum or clavicle (97% vs. 91%). Moreover, the sensitivity was found to be higher when the procedure was carried out by a radiologist in comparison to an emergency medicine specialist (96% vs. 90%). Base on the findings of the present meta-analysis, screening performance characteristic of ultrasonography in detection of thoracic bone fractures was found to be higher than radiography. However, these characteristics were more prominent in detection of rib fractures and in cases where was performed by a radiologist.

  13. The Fracture of Plasma-Treated Polyurethane Surface under Fatigue Loading

    Directory of Open Access Journals (Sweden)

    Ilya A. Morozov

    2018-02-01

    Full Text Available Plasma treatment of soft polymers is a promising technique to improve biomedical properties of the materials. The response to the deformation of such materials is not yet clear. Soft elastic polyurethane treated with plasma immersion ion implantation is subjected to fatigue uniaxial loading. The influence of the strain amplitude and the plasma treatment regime on damage character is discussed. Surface defects are studied in unloaded and stretched states of the material. As a result of fatigue loading, transverse cracks (with closed overlapping edges as well as with open edges deeply propagating into the polymer and longitudinal folds which are break and bend inward, appear on the surface. Hard edges of cracks cut the soft polymer which is squeezed from the bulk to the surface. The observed damages are related to the high stiffness of the modified surface and its transition to the polymer substrate.

  14. Thermal analysis of fractures at Cerberus Fossae, Mars: Detection of air convection in the porous debris apron

    Science.gov (United States)

    Antoine, R.; Lopez, T.; Baratoux, D.; Rabinowicz, M.; Kurita, K.

    2011-08-01

    This study investigates the cause of high nighttime temperatures within Cerberus Fossae, a system of fractures affecting the Central Elysium Planitia. The inner parts (walls and floor) of the fractures are up to 40 K warmer than the surrounding plains. However, several temperature profiles exhibit a local temperature minima occurring in the central part of the fractures. We examined first the influence of cooling efficiency at night in the case of a strong reduction of the sky proportion induced by the fracture's geometry. However, the lack of correlation between temperature and sky proportion, calculated from extracted Mars Orbiter Laser Altimeter (MOLA) profiles argues against this hypothesis. Albedo variations were considered but appear to be limited within the fractures, and are generally not correlated with the temperatures. Variations of the thermal properties of bedrocks exposures, debris aprons and sand dunes inferred from high-resolution images do not either correlate with temperature variations within the fractures. As none of these factors taken alone, or combined, can satisfactorily explain the temperature variations within and near the fracture, we suggest that geothermal heat transported by air convection within the porous debris aprons may contribute to explain high temperatures at night and the local minima on the fracture floor. The conditions for the occurrence of the suggested phenomenon and the consequences on the surface temperature are numerically explored. A conservative geothermal gradient of 20 mW/m 2 was used in the simulations, this value being consistent with either inferred lithosphere elastic thicknesses below the shield volcanoes of the Tharsis dome or values predicted from numerical simulations of the thermal evolution of Mars. The model results indicate that temperature differences of 10-20 K between the central and upper parts of the fracture are explained in the case of high Darcy velocities which require high permeability values

  15. Hip fracture in the elderly: a re-analysis of the EPIDOS study with causal Bayesian networks.

    Science.gov (United States)

    Caillet, Pascal; Klemm, Sarah; Ducher, Michel; Aussem, Alexandre; Schott, Anne-Marie

    2015-01-01

    Hip fractures commonly result in permanent disability, institutionalization or death in elderly. Existing hip-fracture predicting tools are underused in clinical practice, partly due to their lack of intuitive interpretation. By use of a graphical layer, Bayesian network models could increase the attractiveness of fracture prediction tools. Our aim was to study the potential contribution of a causal Bayesian network in this clinical setting. A logistic regression was performed as a standard control approach to check the robustness of the causal Bayesian network approach. EPIDOS is a multicenter study, conducted in an ambulatory care setting in five French cities between 1992 and 1996 and updated in 2010. The study included 7598 women aged 75 years or older, in which fractures were assessed quarterly during 4 years. A causal Bayesian network and a logistic regression were performed on EPIDOS data to describe major variables involved in hip fractures occurrences. Both models had similar association estimations and predictive performances. They detected gait speed and mineral bone density as variables the most involved in the fracture process. The causal Bayesian network showed that gait speed and bone mineral density were directly connected to fracture and seem to mediate the influence of all the other variables included in our model. The logistic regression approach detected multiple interactions involving psychotropic drug use, age and bone mineral density. Both approaches retrieved similar variables as predictors of hip fractures. However, Bayesian network highlighted the whole web of relation between the variables involved in the analysis, suggesting a possible mechanism leading to hip fracture. According to the latter results, intervention focusing concomitantly on gait speed and bone mineral density may be necessary for an optimal prevention of hip fracture occurrence in elderly people.

  16. Characterizing Fractures Across the Astronaut Corps: Preliminary Findings from Population-Level Analysis

    Science.gov (United States)

    Rossi, Meredith M.; Charvat, Jacqueline M.; Sibonga, Jean D.; Sieker, Jeremy

    2017-01-01

    Despite evidence of bone loss during spaceflight and the implementation of countermeasures to mitigate this loss, the subsequent risk of fracture among astronauts is not known. Multiple factors such as age, sex, fracture history, and others may combine to increase fracture risk. The purpose of this study was to describe fractures among the astronaut population and generate questions for future occupational surveillance studies.

  17. Prospective Computed Tomographic Analysis of Osteochondral Lesions of the Ankle Joint Associated With Ankle Fractures

    NARCIS (Netherlands)

    Nosewicz, Tomasz L.; Beerekamp, M. Suzan H.; de Muinck Keizer, Robert-Jan O.; Schepers, Tim; Maas, Mario; Niek van Dijk, C.; Goslings, J. Carel

    2016-01-01

    Osteochondral lesions (OCLs) associated with ankle fracture correlate with unfavorable outcome. The goals of this study were to detect OCLs following ankle fracture, to associate fracture type to OCLs and to investigate whether OCLs affect clinical outcome. 100 ankle fractures requiring operative

  18. Surface analysis methods in materials science

    CERN Document Server

    Sexton, Brett; Smart, Roger

    1992-01-01

    The idea for this book stemmed from a remark by Philip Jennings of Murdoch University in a discussion session following a regular meeting of the Australian Surface Science group. He observed that a text on surface analysis and applica­ tions to materials suitable for final year undergraduate and postgraduate science students was not currently available. Furthermore, the members of the Australian Surface Science group had the research experience and range of coverage of sur­ face analytical techniques and applications to provide a text for this purpose. A of techniques and applications to be included was agreed at that meeting. The list intended readership of the book has been broadened since the early discussions, particularly to encompass industrial users, but there has been no significant alter­ ation in content. The editors, in consultation with the contributors, have agreed that the book should be prepared for four major groups of readers: - senior undergraduate students in chemistry, physics, metallur...

  19. Fracture mechanics analysis of reactor pressure vessel under pressurized thermal shock - The effect of elastic-plastic behavior and stainless steel cladding -

    International Nuclear Information System (INIS)

    Joo, Jae Hwang; Kang, Ki Ju; Jhung, Myung Jo

    2002-01-01

    Performed here is an assessment study for deterministic fracture mechanics analysis of a pressurized thermal shock (PTS). The PTS event means an event or transient in pressurized water reactors (PWRs) causing severe overcooling (thermal shock) concurrent with or followed by significant pressure in the reactor vessel. The problems consisting of two transients and 10 cracks are solved and maximum stress intensity factors and maximum allowable nil-ductility reference temperatures are calculated. Their results are compared each other to address the general characteristics between transients, crack types and analysis methods. The effects of elastic-plastic material behavior and clad coating on the inner surface are explored

  20. Electroperturbation of human stratum corneum fine structure by high voltage pulses: a freeze-fracture electron microscopy and differential thermal analysis study.

    Science.gov (United States)

    Jadoul, A; Tanojo, H; Préat, V; Bouwstra, J A; Spies, F; Boddé, H E

    1998-08-01

    Application of high voltage pulses (HVP) to the skin has been shown to promote the transdermal drug delivery by a mechanism involving skin electroporation. The aim of this study was to detect potential changes in lipid phase and ultrastructure induced in human stratum corneum by various HVP protocols, using differential thermal analysis and freeze-fracture electron microscopy. Due to the time involved between the moment the electric field is switched off and the analysis, only "secondary" phenomena rather than primary events could be observed. A decrease in enthalpies for the phase transitions observed at 70 degrees C and 85 degrees C was detected by differential thermal analysis after HVP treatment. No changes in transition temperature could be seen. The freeze-fracture electron microscopy study revealed a dramatic perturbation of the lamellar ordering of the intercellular lipid after application of HVP. Most of the planes displayed rough surfaces. The lipid lamellae exhibited rounded off steps or a vanished stepwise order. There was no evidence for perturbation of the corneocytes content. In conclusion, the freeze-fracture electron microscopy and differential thermal analysis studies suggest that HVP application induces a general perturbation of the stratum corneum lipid ultrastructure.

  1. Comparison of analgesic interventions for traumatic rib fractures: a systematic review and meta-analysis.

    Science.gov (United States)

    Peek, Jesse; Smeeing, Diederik P J; Hietbrink, Falco; Houwert, Roderick M; Marsman, Marije; de Jong, Mirjam B

    2018-02-06

    Many studies report on outcomes of analgesic therapy for (suspected) traumatic rib fractures. However, the literature is inconclusive and diverse regarding the management of pain and its effect on pain relief and associated complications. This systematic review and meta-analysis summarizes and compares reduction of pain for the different treatment modalities and as secondary outcome mortality during hospitalization, length of mechanical ventilation, length of hospital stay, length of intensive care unit stay (ICU) and complications such as respiratory, cardiovascular, and/or analgesia-related complications, for four different types of analgesic therapy: epidural analgesia, intravenous analgesia, paravertebral blocks and intercostal blocks. PubMed, EMBASE and CENTRAL databases were searched to identify comparative studies investigating epidural, intravenous, paravertebral and intercostal interventions for traumatic rib fractures, without restriction for study type. The search strategy included keywords and MeSH or Emtree terms relating blunt chest trauma (including rib fractures), analgesic interventions, pain management and complications. A total of 19 papers met our inclusion criteria and were finally included in this systematic review. Significant differences were found in favor of epidural analgesia for the reduction of pain. No significant differences were observed between epidural analgesia, intravenous analgesia, paravertebral blocks and intercostal blocks, for the secondary outcomes. Results of this study show that epidural analgesia provides better pain relief than the other modalities. No differences were observed for secondary endpoints like length of ICU stay, length of mechanical ventilation or pulmonary complications. However, the quality of the available evidence is low, and therefore, preclude strong recommendations.

  2. Photoelastic stress analysis assisted evaluation of fracture toughness in hydrothermally aged epoxies

    Directory of Open Access Journals (Sweden)

    G. Pitarresi

    2014-10-01

    Full Text Available The present work has investigated the fracture toughness of a model DGEBA epoxy system subject to Hidro-Thermal aging. A Photoelastic Stress Analysis technique has been implemented, showing the evolution of stresses arising throughout the water uptake process due to the non-uniform swelling of the material. Gravimetric and Dynamic Mechanical Thermal Analyses have further complemented the characterization, showing the onset of plasticization effects with aging. The correlation of all previous characterizations has allowed to conclude that an increase of KIC fracture toughness is obtained at the fully saturated condition. In particular Photoelasticity has also revealed the onset of relevant swelling induced stresses during the first stages of water absorption, leading to an increase of fracture toughness due to compressive stresses settling near the crack tip. A stress free condition is instead reestablished at the later stages of absorption, suggesting that the increased toughness of the saturated material is an effect of the modifications induced by aging on the polymer structure.

  3. An analysis of postoperative hemoglobin levels in patients with a fractured neck of femur.

    Science.gov (United States)

    Nagra, Navraj S; van Popta, Dmitri; Whiteside, Sigrid; Holt, Edward M

    2016-10-01

    The aim of this study was to analyze the changes in hemoglobin level and to determine a suitable timeline for post-operative hemoglobin monitoring in patients undergoing fixation of femoral neck fracture. Patients who underwent either dynamic hip screw (DHS) fixation (n = 74, mean age: 80 years) or hip hemiarthroplasty (n = 104, mean age: 84 years) for femoral neck fracture were included into the study. The hemoglobin level of the patients was monitored perioperatively. Analysis found a statistically and clinically significant mean drop in hemoglobin of 31.1 g/L over time from pre-operatively (D0) to day-5 post-operatively (p hemoglobin values over hemiarthroplasty patients (p = 0.046). The decrease in hemoglobin in the first 24-h post-operative period (D0 to day-1) is an underestimation of the ultimate lowest value in hemoglobin found at day-2. Relying on the day-1 hemoglobin could be detrimental to patient care. We propose a method of predicting patients likely to be transfused, and recommend a protocol for patients undergoing femoral neck fracture surgery to standardize postoperative hemoglobin monitoring. Level IV Prognostic study. Copyright © 2016 Turkish Association of Orthopaedics and Traumatology. Production and hosting by Elsevier B.V. All rights reserved.

  4. Microstructure analysis for quantification of Barkhausen noise method and nondestructive evaluation of fracture characteristics

    International Nuclear Information System (INIS)

    Kim, Dong Won; Kwon, Dong Il

    1999-01-01

    Barkhausen noise method as a magnetic nondestructive test has the advantages for evaluating the properties of magnetic material more precisely and high-sensitively compared to other magnetic NDT methods. For a long time Barkhausen noise method was applied to measure the bulk magnetic properties of magnetic materials and recently to evaluate microstructure, stress analysis, fatigue, creep, and fracture characteristics as a NDT method. But so far Barkhausen noise method has been used as evaluating orientation of material properties rather qualitatively. For this reason, many NDT testing methods have seldom been applied to industrial plants and laboratories. In this study we make experiments on the variation of Barkhausen noise as microstructure, and quantify Barkhausen noise(rms voltage) via formula of velocity of magnetic domain walls using coercive force as retarding force of domain wall movement. As a result, we could evaluate the microstructure of magnetic materials and trends of fracture toughness quantitatively by measuring Barkhausen noise, therefore directly evaluate microstructure and fracture toughness by Barkhausen noise method as accurate in-situ nondestructive testing method.

  5. A Simulation Model for Tensile Fracture Procedure Analysis of Graphite Material based on Damage Evolution

    International Nuclear Information System (INIS)

    Zhao Erqiang; Ma Shaopeng; Wang Hongtao

    2014-01-01

    Graphite material is generally easy to be damaged by the widely distributed micro-cracks when subjects to load. For numerically analyzing of the structure made of graphite material, the influences of the degradation of the material in damaged areas need to be considered. In this paper, an axial tension test method is proposed to obtain the dynamic damage evolution rule of the material. Using the degradation rule (variation of elastic modulus), the finite element model is then constructed to analyze the tensile fracture process of the L-shaped graphite specimen. An axial tension test of graphite is performed to obtain the stress-strain curve. Based on the variation of the measured curve, the damage evolution rule of the material are fitted out. A simulation model based on the above measured results is then constructed on ABAQUS by user subroutine. Using this simulation model, the tension failure process of L-shaped graphite specimen with fillet are simulated. The calculated and experimental results on fracture load are in good agreement. The damage simulation model based on the stress-strain curve of axial tensile test can be used in other tensile fracture analysis. (author)

  6. Efficient diagnostic evaluation of fractures of the talus - an analysis based on examination of 40 patients

    International Nuclear Information System (INIS)

    Foerster, A.; Roehnert, W.; Koehler, K.

    1997-01-01

    Conventional radiography imaging the ankle joint in two planes is the initial technique applied, giving information on further diagnostic evaluation required. CT is of importance for such additional examination, and spiral CT in particular, as it can generate directly comparable pictures due to its standardised examination techniques. Joint surfaces are visualized without superpositions. Fractures and their numbers, dislocations as well as involvement of joint surfaces can be better detected. Also, spiral CT, due to the continuous data set generated, permits 2D reconstructions of high quality. 3D Reconstructions as a rule do not supply additional information. CT can be applied for diagnostic evaluation of the tendon and ligamentum system/soft tissue, but MRI will yield better results. (orig./CB) [de

  7. An interaction analysis of twin surface cracks by the line-spring model

    International Nuclear Information System (INIS)

    Kim, Y.J.; Yang, W.H.; Choy, Y.S.; Lee, J.S.

    1992-01-01

    The fracture mechanics analysis of surface cracks is important for the integrity evaluation of flawed structural components. The objective of this paper is to numerically investigate the interaction effect of twin surface cracks in plate and cylindrical geometrie. First the usefulness of the line-spring model is verified by analyzing a single surface crack in a plate, and then the model is extended to twin surface crack in plate and cylindrical geometries. For the case of a finite plate under uniaxial loading, the effect of crack spacing on the stress intensity factor is negligible. However, for the case of a cylinder under moderate internal pressure, a significant increase in stress intensity factor is observed at the deepest point of the surface crack. (orig.)

  8. Microseismic Analysis of Fracture of an Intact Rock Asperity Traversing a Sawcut Fault

    Science.gov (United States)

    Mclaskey, G.; Lockner, D. A.

    2017-12-01

    Microseismic events carry information related to stress state, fault geometry, and other subsurface properties, but their relationship to large and potentially damaging earthquakes is not well defined. We conducted laboratory rock mechanics experiments that highlight the interaction between a sawcut fault and an asperity composed of an intact rock "pin". The sample is a 76 mm diameter cylinder of Westerly granite with a 21 mm diameter cylinder (the pin) of intact Westerly granite that crosses the sawcut fault. Upon loading to 80 MPa in a triaxial machine, we first observed a slip event that ruptured the sawcut fault, slipped about 35 mm, but was halted by the rock pin. With continued loading, the rock pin failed in a swarm of thousands of M -7 seismic events similar to the localized microcracking that occurs during the final fracture nucleation phase in an intact rock sample. Once the pin was fractured to a critical point, it permitted complete rupture events on the sawcut fault (stick-slip instabilities). No seismicity was detected on the sawcut fault plane until the pin was sheared. Subsequent slip events were preceded by 10s of foreshocks, all located on the fault plane. We also identified an aseismic zone on the fault plane surrounding the fractured rock pin. A post-mortem analysis of the sample showed a thick gouge layer where the pin intersected the fault, suggesting that this gouge propped open the fault and prevented microseismic events in its vicinity. This experiment is an excellent case study in microseismicity since the events separate neatly into three categories: slip on the sawcut fault, fracture of the intact rock pin, and off-fault seismicity associated with pin-related rock joints. The distinct locations, timing, and focal mechanisms of the different categories of microseismic events allow us to study how their occurrence is related to the mechanics of the deforming rock.

  9. Free-Surface flow dynamics and its effect on travel time distribution in unsaturated fractured zones - findings from analogue percolation experiments

    Science.gov (United States)

    Noffz, Torsten; Kordilla, Jannes; Dentz, Marco; Sauter, Martin

    2017-04-01

    Flow in unsaturated fracture networks constitutes a high potential for rapid mass transport and can therefore possibly contributes to the vulnerability of aquifer systems. Numerical models are generally used to predict flow and transport and have to reproduce various complex effects of gravity-driven flow dynamics. However, many classical volume-effective modelling approaches often do not grasp the non-linear free surface flow dynamics and partitioning behaviour at fracture intersections in unsaturated fracture networks. Better process understanding can be obtained by laboratory experiments, that isolate single aspects of the mass partitioning process, which influence travel time distributions and allow possible cross-scale applications. We present a series of percolation experiments investigating partitioning dynamics of unsaturated multiphase flow at an individual horizontal fracture intersection. A high precision multichannel dispenser is used to establish gravity-driven free surface flow on a smooth and vertical PMMA (poly(methyl methacrylate)) surface at rates ranging from 1.5 to 4.5 mL/min to obtain various flow modes (droplets; rivulets). Cubes with dimensions 20 x 20 x 20 cm are used to create a set of simple geometries. A digital balance provides continuous real-time cumulative mass bypassing the network. The influence of variable flow rate, atmospheric pressure and temperature on the stability of flow modes is shown in single-inlet experiments. Droplet and rivulet flow are delineated and a transition zone exhibiting mixed flow modes can be determined. Furthermore, multi-inlet setups with constant total inflow rates are used to reduce variance and the effect of erratic free-surface flow dynamics. Investigated parameters include: variable aperture widths df, horizontal offsets dv of the vertical fracture surface and alternating injection methods for both droplet and rivulet flow. Repetitive structures with several horizontal fractures extend arrival times

  10. Detailed analysis of surface asperity deformation mechanism in diffusion bonding of steel hollow structural components

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, C. [School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072 (China); Laboratoire de Mecanique des Contacts et des Structures (LaMCoS), INSA Lyon, 20 Avenue des Sciences, F-69621 Villeurbanne Cedex (France); Li, H. [School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072 (China); Li, M.Q., E-mail: zc9997242256@126.com [School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072 (China)

    2016-05-15

    Graphical abstract: This study focused on the detailed analysis of surface asperity deformation mechanism in diffusion bonding of steel hollow structural component. A special surface with regular patterns was processed to be joined so as to observe the extent of surface asperity deformation under different applied bonding pressures. Fracture surface characteristic combined with surface roughness profiles distinctly revealed the enhanced surface asperity deformation as the applied pressure increases. The influence of surface asperity deformation mechanism on joint formation was analyzed: (a) surface asperity deformation not only directly expanded the interfacial contact areas, but also released deformation heat and caused defects, indirectly accelerating atomic diffusion, then benefits to void shrinkage; (b) surface asperity deformation readily introduced stored energy difference between two opposite sides of interface grain boundary, resulting in strain induced interface grain boundary migration. In addition, the influence of void on interface grain boundary migration was analyzed in detail. - Highlights: • A high quality hollow structural component has been fabricated by diffusion bonding. • Surface asperity deformation not only expands the interfacial contact areas, but also causes deformation heat and defects to improve the atomic diffusion. • Surface asperity deformation introduces the stored energy difference between the two opposite sides of interface grain boundary, leading to strain induced interface grain boundary migration. • The void exerts a dragging force on the interface grain boundary to retard or stop interface grain boundary migration. - Abstract: This study focused on the detailed analysis of surface asperity deformation mechanism in similar diffusion bonding as well as on the fabrication of high quality martensitic stainless steel hollow structural components. A special surface with regular patterns was processed to be joined so as to

  11. Surface analysis by RBS and NRA

    International Nuclear Information System (INIS)

    Braun, M.

    1984-01-01

    The use of Rutherford backscattering spectroscopy (RBS) and nuclear reaction analysis (NRA) for surface analysis is discussed. For the RBS technique, emphasis is laid on cases which are not discussed in existing review articles of the subject. The present work intends to describe a calculation procedure with the aid of which it is possible to obtain the depth distribution of a high concentration and non-homogeneously binary compound sample. This complicates the determination of the stopping and scattering cross-sections of the incoming particles at a certain depth below the surface. In addition, a method is described by which the thickness and composition of a two-element film, deposited on a single-element substrate, can be determined by RBS. One advantage with the method presented here is that it is not necessary to detect any signals from the lighter component of the film, in order to determine the composition. This improves the RBS technique to study light elements in connection with thin layers. Finally, the NRA method to measure concentration distributions of deuterium beneath a surface is presented. In the case discussed here, the analysis is done by the D( 3 He, H) 4 He nuclear reaction. (author)

  12. SURFAN, a programme for surface analysis

    International Nuclear Information System (INIS)

    Negoita, F.; Borcan, C.; Pantelica, D.

    1997-01-01

    Possible alternatives to Rutherford backscattering spectrometry (RBS) method of material analysis, overcoming the poor sensitivity to light elements of RBS, are the nuclear resonant reaction analysis (NRA) and elastic recoil detection analysis (ERDA). The last one is especially useful in surface and thin film analysis. To simulate the spectra obtained with any of these methods a programme SURFAN was worked out. In comparison with the code RUMP, published by Doolittle, it allows to simply change the charge of the projectile nature, implies no limitation to the energy of incident projectiles and permits the use of any depth profile function. The basic ideas and the structure of SURFAN are presented. Its application to ERDA and RBS methods resulted in important information on the processes implied in special materials obtained by advanced technologies

  13. Exposure to Fluoride in Drinking Water and Hip Fracture Risk: A Meta-Analysis of Observational Studies

    OpenAIRE

    Yin, Xin-Hai; Huang, Guang-Lei; Lin, Du-Ren; Wan, Cheng-Cheng; Wang, Ya-Dong; Song, Ju-Kun; Xu, Ping

    2015-01-01

    Background Many observational studies have shown that exposure to fluoride in drinking water is associated with hip fracture risk. However, the findings are varied or even contradictory. In this work, we performed a meta-analysis to assess the relationship between fluoride exposure and hip fracture risk. Methods PubMed and EMBASE databases were searched to identify relevant observational studies from the time of inception until March 2014 without restrictions. Data from the included studies w...

  14. Effects of multiple root canal usage on the surface topography and fracture of two different Ni-Ti rotary file systems

    Directory of Open Access Journals (Sweden)

    Jojo Kottoor

    2013-01-01

    Full Text Available Aim: The purpose of this study was to evaluate the effect of multiple root canal usage on the surface topography and fracture of Twisted File (TF and ProTaper (PT rotary Ni-Ti file systems, using scanning electron microscope (SEM. Materials and Methods: Ten sets of PT and TF instruments were used to prepare the mesial canals of mandibular first molars. TF 25, 0.06 taper and PT F1 instruments were analyzed by SEM when new and thereafter every three root canal usages. This sequence was repeated for both the TF and PT groups until 12 uses. Two images of the instrument were recorded, one of the instrument tip and the other 5 mm from the tip, both at ×100 magnification. The sequential use was continued till the instrument fractured and the number of root canal usages for the file to fracture was noted. All fracture surfaces were examined under the SEM. Results: Fresh TF instruments showed no surface wear when compared to PT instruments (P 0.05, while at the 9 th usage TF showed a steep increase in the spiral distortion score when compared to PT (P < 0.05. PT instruments fractured at a mean root canal usage of 17.4, while TF instruments showed a mean root canal usage of 11.8. Fractographically, all the TF instruments failed due to torsion, while all the PT instruments failed because of cyclic fatigue. Conclusion: PT instruments showed more resistance to fracture than TF instruments.

  15. User's manuals of probabilistic fracture mechanics analysis code for aged piping, PASCAL-SP

    International Nuclear Information System (INIS)

    Itoh, Hiroto; Nishikawa, Hiroyuki; Onizawa, Kunio; Kato, Daisuke; Osakabe, Kazuya

    2010-03-01

    As a part of research on the material degradation and structural integrity assessment for aged LWR components, a PFM (Probabilistic Fracture Mechanics) analysis code PASCAL-SP (PFM Analysis of Structural Components in Aging LWR - Stress Corrosion Cracking at Welded Joints of Piping) has been developed. This code evaluates the failure probabilities at welded joints of aged piping by a Monte Carlo method. PASCAL-SP treats stress corrosion cracking (SCC) and fatigue crack growth in piping, according to the approaches of NISA and JSME FFS Code. The development of the code has been aimed to improve the accuracy and reliability of analysis by introducing new analysis methodologies and algorithms considering the latest knowledge in the SCC assessment and fracture criteria of piping. In addition, the accuracy of flaw detection and sizing at in-service inspection and residual stress distribution were modeled based on experimental data and introduced into PASCAL-SP. This code has been developed for a cross-check use by the regulatory body in Japan. In addition to this, this code can also be used for a research purpose by researchers in academia and industries. This report provides the user's manual and theoretical background of the code. (author)

  16. Ceramic-on-ceramic bearing fractures in total hip arthroplasty: an analysis of data from the National Joint Registry.

    Science.gov (United States)

    Howard, D P; Wall, P D H; Fernandez, M A; Parsons, H; Howard, P W

    2017-08-01

    Ceramic-on-ceramic (CoC) bearings in total hip arthroplasty (THA) are commonly used, but concerns exist regarding ceramic fracture. This study aims to report the risk of revision for fracture of modern CoC bearings and identify factors that might influence this risk, using data from the National Joint Registry (NJR) for England, Wales, Northern Ireland and the Isle of Man. We analysed data on 223 362 bearings from 111 681 primary CoC THAs and 182 linked revisions for bearing fracture recorded in the NJR. We used implant codes to identify ceramic bearing composition and generated Kaplan-Meier estimates for implant survivorship. Logistic regression analyses were performed for implant size and patient specific variables to determine any associated risks for revision. A total of 222 852 bearings (99.8%) were CeramTec Biolox products. Revisions for fracture were linked to seven of 79 442 (0.009%) Biolox Delta heads, 38 of 31 982 (0.119%) Biolox Forte heads, 101 of 80 170 (0.126%) Biolox Delta liners and 35 of 31 258 (0.112%) Biolox Forte liners. Regression analysis of implant size revealed smaller heads had significantly higher odds of fracture (chi-squared 68.0, p ceramic type. Liner thickness was not predictive of fracture (p = 0.67). Body mass index (BMI) was independently associated with revision for both head fractures (odds ratio (OR) 1.09 per unit increase, p = 0.031) and liner fractures (OR 1.06 per unit increase, p = 0.006). We report the largest independent study of CoC bearing fractures to date. The risk of revision for CoC bearing fracture is very low but previous studies have underestimated this risk. There is good evidence that the latest generation of ceramic has greatly reduced the odds of head fracture but not of liner fracture. Small head size and high patient BMI are associated with an increased risk of ceramic bearing fracture. Cite this article: Bone Joint J 2017;99-B:1012-19. ©2017 The British Editorial Society of Bone & Joint Surgery.

  17. Analysis of interlaminar fracture toughness and damage mechanisms in composite laminates reinforced with sprayed multi-walled carbon nanotubes

    KAUST Repository

    Almuhammadi, Khaled; Alfano, Marco; Yang, Yang; Lubineau, Gilles

    2014-01-01

    The present work is focused on the nanoreinforcement of prepreg based carbon fiber composite laminates to improve delamination resistance. Functionalized multi-walled carbon nanotubes (MWCNTs) were dispersed over the interface between prepreg layers through solvent spraying and the resulting mode I interlaminar fracture toughness was determined. For comparison, baseline samples with neat prepregs were also prepared. Results indicate that the introduction of functionalized MWCNTs can favorably affect the interlaminar fracture toughness, and the associated mechanisms of failure have been investigated. The manufacturing procedures and the interfacial reinforcing mechanism were explored by analyzing (i) the wettability between CNTs-solvent solution and prepreg surface, (ii) CNTs dispersion and (iii) the fractured surfaces through high resolution scanning electron microscopy and Raman mapping. © 2013 Elsevier Ltd.

  18. Surface Properties of TNOs: Preliminary Statistical Analysis

    Science.gov (United States)

    Antonieta Barucci, Maria; Fornasier, S.; Alvarez-Cantal, A.; de Bergh, C.; Merlin, F.; DeMeo, F.; Dumas, C.

    2009-09-01

    An overview of the surface properties based on the last results obtained during the Large Program performed at ESO-VLT (2007-2008) will be presented. Simultaneous high quality visible and near-infrared spectroscopy and photometry have been carried out on 40 objects with various dynamical properties, using FORS1 (V), ISAAC (J) and SINFONI (H+K bands) mounted respectively at UT2, UT1 and UT4 VLT-ESO telescopes (Cerro Paranal, Chile). For spectroscopy we computed the spectral slope for each object and searched for possible rotational inhomogeneities. A few objects show features in their visible spectra such as Eris, whose spectral bands are displaced with respect to pure methane-ice. We identify new faint absorption features on 10199 Chariklo and 42355 Typhon, possibly due to the presence of aqueous altered materials. The H+K band spectroscopy was performed with the new instrument SINFONI which is a 3D integral field spectrometer. While some objects show no diagnostic spectral bands, others reveal surface deposits of ices of H2O, CH3OH, CH4, and N2. To investigate the surface properties of these bodies, a radiative transfer model has been applied to interpret the entire 0.4-2.4 micron spectral region. The diversity of the spectra suggests that these objects represent a substantial range of bulk compositions. These different surface compositions can be diagnostic of original compositional diversity, interior source and/or different evolution with different physical processes affecting the surfaces. A statistical analysis is in progress to investigate the correlation of the TNOs’ surface properties with size and dynamical properties.

  19. Correlation between Condylar Fracture Pattern after Parasymphyseal Impact and Condyle Morphological Features: A Retrospective Analysis of 107 Chinese Patients.

    Science.gov (United States)

    Han, Lu; Long, Ting; Tang, Wei; Liu, Lei; Jing, Wei; Tian, Wei-Dong; Long, Jie

    2017-02-20

    The treatment of the condylar fractures is difficult. Factors that result in the fractures are complex. The objective of this morphometric study was to investigate the relationship between condylar fracture patterns and condylar morphological characteristics. We conducted a retrospective analysis of 107 patients admitted to the West China Hospital of Stomatology for bilateral condylar fractures caused by parasymphyseal impact. The patients were divided into five groups according to the type of condylar fracture. Ten parameters were evaluated on three-dimensional (3D) reconstruction mandible models through the Mimics 16.0 (Materialize Leuven, Belgium) anthropometry toolkit. Each parameter of the 3D models was analyzed using multivariate analysis. Multinomial logistic regression analyses were used to examine the relationships between the five groups. The results showed that the differences of condylar head width (M1), condylar neck width (M3), the ratio of condylar head width to condylar anteroposterior diameter (M1/M2), the ratio of condylar head width to condylar neck width (M1/M3), the ratio of condylar height to ramus height (M8/M7), and mandibular angle (M10) were statistically significant (p fractures were positively associated with M1 (compared to Type B: OR =1.627, 95% CI: 1.123, 2.359; compared to Type C: OR = 1.705, 95% CI: 1.170, 2.484) and M1/M2 (compared to Type B: OR =1.034, 95% CI: 0.879, 2.484). Type B condylar head fractures were negatively associated with M10 (compared to Type C: OR = 0.909, 95% CI: 0.821, 1.007). Condylar neck fractures were negatively associated with M3 (compared to condylar head: OR = 0.382, CI: 0.203, 0.720 ; compared to condylar base: OR = 0.436, 95% CI: 0.218, 0.874), and positively associated with M1/M3 (compared to condylar head: OR = 1.229, 95% CI: 1.063, 1.420 compared to condylar base: OR = 1.223, 95% CI: 1.034, 1.447). Condylar base fractures were positively associated with M10 (OR = 1.095, 95% CI: 1.008, 1.189) and

  20. On the failure analysis of bondlines: Stress or energy based fracture criteria?

    DEFF Research Database (Denmark)

    Anyfantis, Konstantinos

    2014-01-01

    that characterizes a given bondline, both its cohesive strength and fracture toughness material parameters must be experimentally defined. Based on these properties, failure analysis of the bondline can be done either through stress- or energy-based criteria. The aim of this work is to investigate the effectiveness...... to classify the wide range of bondlines with respect to the failure theory that best describes the debonding process. Cohesive length scale effects are first demonstrated by modeling end notch flexure geometries and later by modeling double strap joint geometries within the framework of a wide numerical...