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Sample records for fracture parameters calculation-part

  1. French RSE-M and RCC-MR code appendices for flaw analysis: Presentation of the fracture parameters calculation-Part V: Elements of validation

    International Nuclear Information System (INIS)

    Marie, S.; Chapuliot, S.; Kayser, Y.; Lacire, M.H.; Drubay, B.; Barthelet, B.; Le Delliou, P.; Rougier, V.; Naudin, C.; Gilles, P.; Triay, M.

    2007-01-01

    French nuclear codes include flaw assessment procedures: the RSE-M Code 'Rules for In-service Inspection of Nuclear Power Plant Components' and the RCC-MR code 'Design and Construction Rules for Mechanical Components of FBR Nuclear Islands and High Temperature Applications'. Development of analytical methods has been made for the last 10 years in the framework of a collaboration between CEA, EDF and AREVA-NP, and by R and D actions involving CEA and IRSN. These activities have led to a unification of the common methods of the two codes. The calculation of fracture mechanics parameters, in particular the stress intensity factor K I and the J integral, has been widely developed for industrial configurations. All the developments have been integrated in the 2005 edition of RSE-M and in 2007 edition of RCC-MR. This series of articles consists of 5 parts: the first part presents an overview of the methods proposed in the RCC-MR and RSE-M codes. Parts II-IV provide the compendia for specific components. The geometries are plates (part II), pipes (part III) and elbows (part IV). This part presents validation of the methods, with details on the process followed for their development and of the evaluation accuracy of the proposed analytical methods

  2. French RSE-M and RCC-MR code appendices for flaw analysis: Presentation of the fracture parameters calculation-Part IV: Cracked elbows

    International Nuclear Information System (INIS)

    Marie, S.; Chapuliot, S.; Kayser, Y.; Lacire, M.H.; Drubay, B.; Barthelet, B.; Le Delliou, P.; Rougier, V.; Naudin, C.; Gilles, P.; Triay, M.

    2007-01-01

    Two French nuclear codes include flaw assessment procedures: the RSE-M Code 'Rules for In-service Inspection of Nuclear Power Plant Components' and the RCC-MR code 'Design and Construction rules for mechanical components of FBR nuclear islands and high temperature applications'. Development of analytical methods has been made for the last 10 years through a collaboration between CEA, EDF and AREVA-NP, and through R and D actions involving CEA and IRSN. These activities have led to unification of the common methods of the two codes. The calculation of fracture mechanics parameters, and in particular the stress intensity factor K I and the J integral, has been widely developed for industrial configurations. All the developments have been integrated in the 2005 edition of RSE-M and in 2007 edition of RCC-MR. This series of papers is composed of five parts: the first presents an overview of the methods proposed in the RCC-MR and RSE-M codes. Parts II-IV provide compendia for specific components. The geometries are plates (part II), pipes (part III) and elbows (part IV). Part V presents validation of the methods, with details on their accuracy. This paper presents the stress intensity factor and J calculation for cracked elbows. General data applicable for all defect geometries are first presented, and then, compendia for K I and σ ref calculations are provided for the available defect geometries

  3. French RSE-M and RCC-MR code appendices for flaw analysis: Presentation of the fracture parameters calculation-Part II: Cracked plates

    International Nuclear Information System (INIS)

    Marie, S.; Chapuliot, S.; Kayser, Y.; Lacire, M.H.; Drubay, B.; Barthelet, B.; Le Delliou, P.; Rougier, V.; Naudin, C.; Gilles, P.; Triay, M.

    2007-01-01

    French nuclear codes include flaw assessment procedures: the RSE-M Code 'Rules for In-service Inspection of Nuclear Power Plant Components' and the RCC-MR code 'Design and Construction rules for mechanical components of FBR nuclear islands and high temperature applications'. An important effort of development of these analytical methods has been made for the last 10 years in the frame of a collaboration between CEA, EDF and AREVA-NP, and in the frame of R and D actions involving CEA and IRSN. These activities have led to a unification of the common methods of the two codes. The calculation of fracture mechanics parameters, and in particular the stress intensity factor K I and the J integral, has been widely developed for industrial configurations. All the developments have been integrated in the 2005 edition of RSE-M and in the 2007 edition of RCC-MR. This series of articles is composed of 5 parts: the first part presents an overview of the methods proposed in the RCC-MR and RSE-M codes. Parts II-IV provide compendia for specific components. The geometries are plates (part II), pipes (part III) and elbows (part IV). Finally, part V presents the validation elements of the methods, with details on the process followed for the development and evaluation of the accuracy of the proposed analytical methods. This second article in the series presents all details for the stress intensity factor and J calculations for cracked plates. General data applicable for all defect geometries are first presented, and then, available defect geometries where compendia for K I and σ ref calculation are provided are given

  4. French RSE-M and RCC-MR code appendices for flaw analysis: Presentation of the fracture parameters calculation-Part I: General overview

    International Nuclear Information System (INIS)

    Marie, S.; Chapuliot, S.; Kayser, Y.; Lacire, M.H.; Drubay, B.; Barthelet, B.; Le Delliou, P.; Rougier, V.; Naudin, C.; Gilles, P.; Triay, M.

    2007-01-01

    Two French nuclear codes include flaw assessment procedures: the RSE-M code 'Rules for In-service Inspection of Nuclear Power Plant Components' and the RCC-MR code 'Design and Construction rules for mechanical components of FBR nuclear islands and high temperature applications'. An important effort of development of these analytical methods has been made for the last 10 years in the frame of a collaboration between CEA, EDF and AREVA-NP, and in the frame of R and D actions involving CEA and IRSN. These activities have led to a unification of the common methods of the two codes. The calculation of fracture mechanics parameters, and in particular the stress intensity factor K I and the J integral, has been widely developed for industrial configurations. All developments have been integrated in the 2005 edition of RSE-M and in the 2007 edition of RCC-MR. This series of articles is composed of five parts: this first one presents an overview of the methods proposed in the RCC-MR and RSE-M codes. Parts II-IV provide compendia for specific components: plates (part II), pipes (part III) and elbows (part IV). Finally, part V presents the validation elements of the methods, with details on the process followed for their development and on evaluation of the accuracy of the proposed analytical methods. This first article of the series presents an overview of the calculation of K I and J in these two codes and describes briefly the defect assessment analyses. Specific details in the Appendix A16 of RCC-MR (LBB procedure and creep analyses) are also introduced in this article

  5. 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...

  6. Estimation of fracture parameters using elastic full-waveform inversion

    KAUST Repository

    Zhang, Zhendong

    2017-08-17

    Current methodologies to characterize fractures at the reservoir scale have serious limitations in spatial resolution and suffer from uncertainties in the inverted parameters. Here, we propose to estimate the spatial distribution and physical properties of fractures using full-waveform inversion (FWI) of multicomponent surface seismic data. An effective orthorhombic medium with five clusters of vertical fractures distributed in a checkboard fashion is used to test the algorithm. A shape regularization term is added to the objective function to improve the estimation of the fracture azimuth, which is otherwise poorly constrained. The cracks are assumed to be penny-shaped to reduce the nonuniqueness in the inverted fracture weaknesses and achieve a faster convergence. To better understand the inversion results, we analyze the radiation patterns induced by the perturbations in the fracture weaknesses and orientation. Due to the high-resolution potential of elastic FWI, the developed algorithm can recover the spatial fracture distribution and identify localized “sweet spots” of intense fracturing. However, the fracture azimuth can be resolved only using long-offset data.

  7. An Examination Of Fracture Splitting Parameters Of Crackable Connecting Rods

    Directory of Open Access Journals (Sweden)

    Zafer Özdemir

    2000-06-01

    Full Text Available Fracture splitting method is an innovative processing technique in the field of automobile engine connecting rod (con/rod manufacturing. Compared with traditional method, this technique has remarkable advantages. Manufacturing procedures, equipment and tools investment can be decreased and energy consumption reduced remarkably. Furthermore, product quality and bearing capability can also be improved. It provides a high quality, high accuracy and low cost route for producing connecting rods (con/rods. With the many advantages mentioned above, this method has attracted manufacturers attention and has been utilized in many types of con/rod manufacturing. In this article, the method and the advantages it provides, such as materials, notches for fracture splitting, fracture splitting conditions and fracture splitting equipment are discussed in detail. The paper describes an analysis of examination of fracture splitting parameters and optik-SEM fractography of C70S6 crackable connectıng rod. Force and velocity parameters are investigated. That uniform impact force distrubition starting from the starting notch causes brittle and cleavage failure mode is obtained as a result. This induces to decrease the toughness.

  8. Correction of fatigue parameters of concrete using approximation of mechanical-Fracture parameters in time

    Czech Academy of Sciences Publication Activity Database

    Šimonová, H.; Keršner, Z.; Seitl, Stanislav; Pryl, D.; Pukl, R.

    -, č. 1 (2012), s. 57-59 ISSN 1213-3116 R&D Projects: GA ČR(CZ) GAP104/11/0833 Institutional support: RVO:68081723 Keywords : fatigue * concrete * correction * fracture parameters Subject RIV: JL - Materials Fatigue, Friction Mechanics

  9. Two-parameter fracture mechanics: Theory and applications

    International Nuclear Information System (INIS)

    O'Dowd, N.P.; Shih, C.F.

    1993-02-01

    A family of self-similar fields provides the two parameters required to characterize the full range of high- and low-triaxiality crack tip states. The two parameters, J and Q, have distinct roles: J sets the size scale of the process zone over which large stresses and strains develop, while Q scales the near-tip stress distribution relative to a high triaxiality reference stress state. An immediate consequence of the theory is this: it is the toughness values over a range of crack tip constraint that fully characterize the material's fracture resistance. It is shown that Q provides a common scale for interpreting cleavage fracture and ductile tearing data thus allowing both failure modes to be incorporated in a single toughness locus. The evolution of Q, as plasticity progresses from small scale yielding to fully yielded conditions, has been quantified for several crack geometries and for a wide range of material strain hardening properties. An indicator of the robustness of the J-Q fields is introduced; Q as a field parameter and as a pointwise measure of stress level is discussed

  10. Fracture mechanics parameters for glasses: A compilation and correlation

    International Nuclear Information System (INIS)

    Freiman, S.W.; Baker, T.L.; Wachtmann, J.B.

    1985-01-01

    This paper describes a computerized fracture mechanics data base and associated computer programs which permit extension and modification of data base as well as selection, plotting and curve fitting. Some preliminary results of correlations of fracture energy, gamma, with composition and elastic modulus are presented

  11. Estimation of fracture parameters using elastic full-waveform inversion

    KAUST Repository

    Zhang, Zhendong; Alkhalifah, Tariq Ali; Oh, Juwon; Tsvankin, Ilya

    2017-01-01

    regularization term is added to the objective function to improve the estimation of the fracture azimuth, which is otherwise poorly constrained. The cracks are assumed to be penny-shaped to reduce the nonuniqueness in the inverted fracture weaknesses and achieve

  12. Determination of rock fracture parameters from crack models for failure in compression

    International Nuclear Information System (INIS)

    Kemeny, J.M.; Cook, N.G.W.

    1987-01-01

    Micromechanical models for axial splitting and for shear faulting are used to investigate parameters associated with rock fracture under compressive stresses. The fracture energies to create splitting fractures and shear faults are calculated using laboratory triaxial data. These energies are compared with the fracture energies for the propagation of microcracks that coalesce to form the larger scale fractures. It is found that for Westerly granite, the energies to create splitting fractures and shear faults are about three orders of magnitude greater than the energy needed to drive the tensile microcracks, due to the large amount of subsidiary crack surface area created in forming the larger scale fractures. A similar scale effect can be expected when extrapolating the laboratory results to field scale problems

  13. Hydraulic Parameter Generation Technique Using a Discrete Fracture Network with Bedrock Heterogeneity in Korea

    Directory of Open Access Journals (Sweden)

    Jae-Yeol Cheong

    2017-12-01

    Full Text Available In instances of damage to engineered barriers containing nuclear waste material, surrounding bedrock is a natural barrier that retards radionuclide movement by way of adsorption and delay due to groundwater flow through highly tortuous fractured rock pathways. At the Gyeongju nuclear waste disposal site, groundwater mainly flows through granitic and sedimentary rock fractures. Therefore, to understand the nuclide migration path, it is necessary to understand discrete fracture networks based on heterogeneous fracture orientations, densities, and size characteristics. In this study, detailed heterogeneous fracture distribution, including the density and orientation of the fractures, was considered for a region that has undergone long periods of change from various geological activities at and around the Gyeongju site. A site-scale discrete fracture network (DFN model was constructed taking into account: (i regional fracture heterogeneity constrained by a multiple linear regression analysis of fracture intensity on faults and electrical resistivity; and (ii the connectivity of conductive fractures having fracture hydraulic parameters, using transient flow simulation. Geometric and hydraulic heterogeneity of the DFN was upscaled into equivalent porous media for flow and transport simulation for a large-scale model.

  14. Prediction of fracture toughness temperature dependance from tensile test parameters

    Czech Academy of Sciences Publication Activity Database

    Šmida, T.; Babjak, J.; Dlouhý, Ivo

    2010-01-01

    Roč. 48, č. 6 (2010), s. 345-352 ISSN 0023-432X R&D Projects: GA ČR(CZ) GAP108/10/0466; GA AV ČR 1QS200410502 Institutional research plan: CEZ:AV0Z20410507 Keywords : steels * brittle to ductile transition * fracture Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 0.471, year: 2010

  15. A borehole fluid conductivity logging method for the determination of fracture inflow parameters

    International Nuclear Information System (INIS)

    Tsang, C.F.; Hufschmied, P.

    1988-01-01

    It is of much current interest to determine the flow characteristics of fractures intersecting a wellbore in order to provide data in the estimation of the hydrologic behavior of fractured rocks. In particular the fluid inflow rates from the fractures into the wellbore are important quantities to measure. However often these inflows are at very low rates. In addition very often one finds that only a few percent of the fractures identified by core inspection and geophysical logging are water-conducting fractures, the rest being closed, clogged or isolated from the water flow system. A new method has been developed to locate water-conducting fractures and obtain fracture inflow parameters by means of a time sequence of electric conductivity logs of the borehole fluid. The physical basis of the analysis method is discussed. The procedure is applied to an existing set of data, which shows initiation and growth of nine conductivity peaks in a 900-m section of a 1690-m borehole, corresponding to nine waterconducting fractures intersecting the borehole. We are able to match all nine peaks and determine the flow rates from these fractures. A discussion is given on the applicability of this technique in the context of a borehole testing program. (author) 18 refs., 30 figs., 5 tabs

  16. On the temperature independence of statistical model parameters for cleavage fracture in ferritic steels

    Science.gov (United States)

    Qian, Guian; Lei, Wei-Sheng; Niffenegger, M.; González-Albuixech, V. F.

    2018-04-01

    The work relates to the effect of temperature on the model parameters in local approaches (LAs) to cleavage fracture. According to a recently developed LA model, the physical consensus of plastic deformation being a prerequisite to cleavage fracture enforces any LA model of cleavage fracture to observe initial yielding of a volume element as its threshold stress state to incur cleavage fracture in addition to the conventional practice of confining the fracture process zone within the plastic deformation zone. The physical consistency of the new LA model to the basic LA methodology and the differences between the new LA model and other existing models are interpreted. Then this new LA model is adopted to investigate the temperature dependence of LA model parameters using circumferentially notched round tensile specimens. With the published strength data as input, finite element (FE) calculation is conducted for elastic-perfectly plastic deformation and the realistic elastic-plastic hardening, respectively, to provide stress distributions for model calibration. The calibration results in temperature independent model parameters. This leads to the establishment of a 'master curve' characteristic to synchronise the correlation between the nominal strength and the corresponding cleavage fracture probability at different temperatures. This 'master curve' behaviour is verified by strength data from three different steels, providing a new path to calculate cleavage fracture probability with significantly reduced FE efforts.

  17. EGS in sedimentary basins: sensitivity of early-flowback tracer signals to induced-fracture parameters

    Science.gov (United States)

    Karmakar, Shyamal; Ghergut, Julia; Sauter, Martin

    2015-04-01

    Artificial-fracture design, and fracture characterization during or following stimulation treatment is a central aspect of many EGS ('enhanced' or 'engineered' geothermal system) projects. During the creation or stimulation of an EGS, the injection of fluids, followed by flowback and production stages offers the opportunity for conducting various tracer tests in a single-well (SW) configuration, and given the typical operational and time limitations associated with such tests, along with the need to assess treatment success in real time, investigators mostly favour using short-time tracer-test data, rather than awaiting long-term 'tailings' of tracer signals. Late-time tracer signals from SW injection-flowback and production tests have mainly been used for the purpose of multiple-fracture inflow profiling in multi-layer reservoirs [1]. However, the potential of using SW short-term tracer signals for fracture characterization [2, 3] remained little explored as yet. Dealing with short-term flowback signals, we face a certain degree of parameter interplay, leading to ambiguity in fracture parameter inversion from the measured signal of a single tracer. This ambiguity can, to a certain extent, be overcome by - combining different sources of information (lithostratigraphy, and hydraulic monitoring) in order to constrain the variation range of hydrogeologic parameters (matrix and fracture permeability and porosity, fracture size), - using different types of tracers, such as conservative tracer pairs with contrasting diffusivity, or tracers pairs with contrasting sorptivity onto target surfaces. Fracture height is likely to be constrained by lithostratigraphy, while fracture length is supposed to be determinable from hydraulic monitoring (pressure recordings); the flowback rate can be assumed as a known (measurable) quantity during individual-fracture flowback. This leaves us with one or two unknown parameters to be determined from tracer signals: - the transport

  18. Acute changes in foot strike pattern and cadence affect running parameters associated with tibial stress fractures.

    Science.gov (United States)

    Yong, Jennifer R; Silder, Amy; Montgomery, Kate L; Fredericson, Michael; Delp, Scott L

    2018-05-18

    Tibial stress fractures are a common and debilitating injury that occur in distance runners. Runners may be able to decrease tibial stress fracture risk by adopting a running pattern that reduces biomechanical parameters associated with a history of tibial stress fracture. The purpose of this study was to test the hypothesis that converting to a forefoot striking pattern or increasing cadence without focusing on changing foot strike type would reduce injury risk parameters in recreational runners. Running kinematics, ground reaction forces and tibial accelerations were recorded from seventeen healthy, habitual rearfoot striking runners while running in their natural running pattern and after two acute retraining conditions: (1) converting to forefoot striking without focusing on cadence and (2) increasing cadence without focusing on foot strike. We found that converting to forefoot striking decreased two risk factors for tibial stress fracture: average and peak loading rates. Increasing cadence decreased one risk factor: peak hip adduction angle. Our results demonstrate that acute adaptation to forefoot striking reduces different injury risk parameters than acute adaptation to increased cadence and suggest that both modifications may reduce the risk of tibial stress fractures. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. A ductile fracture criterion with Zener-Hollomon parameter of pure molybdenum sheet in thermal forming

    Directory of Open Access Journals (Sweden)

    Wang Chu

    2015-01-01

    Full Text Available Formability of pure molybdenum in thermal forming process has been greatly improved, but it is still hard to avoid the generation of rupture and other quality defects. In this paper, a ductile fracture criterion of pure molybdenum sheet in thermal forming was established by considering the plastic deformation capacity of material and stress states, which can be used to describe fracture behaviour and critical rupture prediction of pure molybdenum sheet during hot forming process. Based on the isothermal uniaxial tensile tests which performed at 993 to 1143 K with strain rate range from 0.0005 to 0.2 s−1, the material parameters are calculated by the combination method of experiment with FEsimulation. Based on the observation, new fracture criteria can be expressed as a function of Zener-Hollomon parameter. The critical fracture value that calculated by Oyane-Sato criterion increases with increasing temperature and decreasing strain rate. The ductile fracture criterion with Zener-Hollomon parameter of pure molybdenum in thermal forming is proposed.

  20. Correlation of fracture parameters during onset of crack in middle tension specimen

    Directory of Open Access Journals (Sweden)

    M.S. Starvin

    2017-07-01

    Full Text Available The present study addresses the implementation of finite element analysis and the prediction of fracture parameters in a middle tension (MT specimen that was fabricated using AISI 4140 steel. The correlation of fracture parameters with external loads and crack sizes was investigated. A Finite Element code was developed to simulate the fracture model. The contour integral method was applied in the calculation of stress intensity factor and J-integral in the cracked specimen. The ASTM standard empirical formula was used to calculate the stress intensity factor (SIF and the numerical predictions were validated. A standard laboratory experiment was also carried out using the MT specimen to calculate the crack growth rate in this specific material. The SIF values were almost linear with external load but it was decreasing as the crack size increases. The crack requires minimum load for crack propagation as the crack size increases. Similarly the J-integral was accelerated with increase in crack size.

  1. The relationship of microstructure and temperature to fracture mechanics parameters in reaction bonded silicon nitride

    International Nuclear Information System (INIS)

    Jennings, H.M.; Dalgleish, B.J.; Pratt, P.L.

    1978-01-01

    The development of physical properties in reaction bonded silicon nitride has been investigated over a range of temperatures and correlated with microstructure. Fracture mechanics parameters, elastic moduli, strength and critical defect size have been determined. The nitrided microstructure is shown to be directly related to these observed properties and these basic relationships can be used to produce material with improved properties. (orig.) [de

  2. Avalanche weak layer shear fracture parameters from the cohesive crack model

    Science.gov (United States)

    McClung, David

    2014-05-01

    Dry slab avalanches release by mode II shear fracture within thin weak layers under cohesive snow slabs. The important fracture parameters include: nominal shear strength, mode II fracture toughness and mode II fracture energy. Alpine snow is not an elastic material unless the rate of deformation is very high. For natural avalanche release, it would not be possible that the fracture parameters can be considered as from classical fracture mechanics from an elastic framework. The strong rate dependence of alpine snow implies that it is a quasi-brittle material (Bažant et al., 2003) with an important size effect on nominal shear strength. Further, the rate of deformation for release of an avalanche is unknown, so it is not possible to calculate the fracture parameters for avalanche release from any model which requires the effective elastic modulus. The cohesive crack model does not require the modulus to be known to estimate the fracture energy. In this paper, the cohesive crack model was used to calculate the mode II fracture energy as a function of a brittleness number and nominal shear strength values calculated from slab avalanche fracture line data (60 with natural triggers; 191 with a mix of triggers). The brittleness number models the ratio of the approximate peak value of shear strength to nominal shear strength. A high brittleness number (> 10) represents large size relative to fracture process zone (FPZ) size and the implications of LEFM (Linear Elastic Fracture Mechanics). A low brittleness number (e.g. 0.1) represents small sample size and primarily plastic response. An intermediate value (e.g. 5) implies non-linear fracture mechanics with intermediate relative size. The calculations also implied effective values for the modulus and the critical shear fracture toughness as functions of the brittleness number. The results showed that the effective mode II fracture energy may vary by two orders of magnitude for alpine snow with median values ranging from 0

  3. Numerical estimate of fracture parameters under elastic and elastic-plastic conditions

    International Nuclear Information System (INIS)

    Soba, Alejandro; Denis, Alicia C.

    2003-01-01

    The importance of the stress intensity factor K in the elastic fracture analysis is well known. In this work three methods are developed to estimate the parameter K I , corresponding to the normal loading mode, employing the finite elements method. The elastic-plastic condition is also analyzed, where the line integral J is the relevant parameter. Two cases of interest are studied: sample with a crack in its center and tubes with internal pressure. (author)

  4. Bayesian Markov Chain Monte Carlo inversion for weak anisotropy parameters and fracture weaknesses using azimuthal elastic impedance

    Science.gov (United States)

    Chen, Huaizhen; Pan, Xinpeng; Ji, Yuxin; Zhang, Guangzhi

    2017-08-01

    A system of aligned vertical fractures and fine horizontal shale layers combine to form equivalent orthorhombic media. Weak anisotropy parameters and fracture weaknesses play an important role in the description of orthorhombic anisotropy (OA). We propose a novel approach of utilizing seismic reflection amplitudes to estimate weak anisotropy parameters and fracture weaknesses from observed seismic data, based on azimuthal elastic impedance (EI). We first propose perturbation in stiffness matrix in terms of weak anisotropy parameters and fracture weaknesses, and using the perturbation and scattering function, we derive PP-wave reflection coefficient and azimuthal EI for the case of an interface separating two OA media. Then we demonstrate an approach to first use a model constrained damped least-squares algorithm to estimate azimuthal EI from partially incidence-phase-angle-stack seismic reflection data at different azimuths, and then extract weak anisotropy parameters and fracture weaknesses from the estimated azimuthal EI using a Bayesian Markov Chain Monte Carlo inversion method. In addition, a new procedure to construct rock physics effective model is presented to estimate weak anisotropy parameters and fracture weaknesses from well log interpretation results (minerals and their volumes, porosity, saturation, fracture density, etc.). Tests on synthetic and real data indicate that unknown parameters including elastic properties (P- and S-wave impedances and density), weak anisotropy parameters and fracture weaknesses can be estimated stably in the case of seismic data containing a moderate noise, and our approach can make a reasonable estimation of anisotropy in a fractured shale reservoir.

  5. Colloid facilitated transport in fractured rocks: parameter estimation and comparison with experimental data

    International Nuclear Information System (INIS)

    Viswanthan, H.S.; Wolfsberg, A.V.; Reimus, P.W.; Ware, D.; Lu, G.

    2003-01-01

    Colloid-facilitated migration of plutonium in fractured rock has been implicated in both field and laboratory studies. Other reactive radionuclides may also experience enhanced mobility due to groundwater colloids. Model prediction of this process is necessary for assessment of contaminant boundaries in systems for which radionuclides are already in the groundwater and for performance assessment of potential repositories for radioactive waste. Therefore, a reactive transport model is developed and parameterized using results from controlled laboratory fracture column experiments. Silica, montmorillonite and clinoptilolite colloids are used in the experiments along with plutonium and Tritium. The goal of the numerical model is to identify and parameterize the physical and chemical processes that affect the colloid-facilitated transport of plutonium in the fractures. The parameters used in this model are similar in form to those that might be used in a field-scale transport model

  6. Ground reaction forces and bone parameters in females with tibial stress fracture.

    Science.gov (United States)

    Bennell, Kim; Crossley, Kay; Jayarajan, Jyotsna; Walton, Elizabeth; Warden, Stuart; Kiss, Z Stephen; Wrigley, Tim

    2004-03-01

    Tibial stress fracture is a common overuse running injury that results from the interplay of repetitive mechanical loading and bone strength. This research project aimed to determine whether female runners with a history of tibial stress fracture (TSF) differ in ground reaction force (GRF) parameters during running, regional bone density, and tibial bone geometry from those who have never sustained a stress fracture (NSF). Thirty-six female running athletes (13 TSF; 23 NSF) ranging in age from 18 to 44 yr were recruited for this cross-sectional study. The groups were well matched for demographic, training, and menstrual parameters. A force platform measured selected GRF parameters (peak and time to peak for vertical impact and active forces, and horizontal braking and propulsive forces) during overground running at 4.0 m.s.(-1). Lumbar spine, proximal femur, and distal tibial bone mineral density were assessed by dual energy x-ray absorptiometry. Tibial bone geometry (cross-sectional dimensions and areas, and second moments of area) was calculated from a computerized tomography scan at the junction of the middle and distal thirds. There were no significant differences between the groups for any of the GRF, bone density, or tibial bone geometric parameters (P > 0.05). Both TSF and NSF subjects had bone density levels that were average or above average compared with a young adult reference range. Factor analysis followed by discriminant function analysis did not find any combinations of variables that differentiated between TSF and NSF groups. These findings do not support a role for GRF, bone density, or tibial bone geometry in the development of tibial stress fractures, suggesting that other risk factors were more important in this cohort of female runners.

  7. Crack propagation direction in a mixed mode geometry estimated via multi-parameter fracture criteria

    Czech Academy of Sciences Publication Activity Database

    Malíková, L.; Veselý, V.; Seitl, Stanislav

    2016-01-01

    Roč. 89, AUG (2016), s. 99-107 ISSN 0142-1123. [International Conference on Characterisation of Crack Tip Fields /3./. Urbino, 20.04.2015-22.04.2015] Institutional support: RVO:68081723 Keywords : Near-crack-tip fields * Mixed mode * Crack propagation direction * Multi-parameter fracture criteria * Finite element analysis Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 2.899, year: 2016

  8. Bone Parameters and Risk of Hip and Femur Fractures in Patients on Hemodialysis

    Science.gov (United States)

    Hazzan, Azzour D.; Jhaveri, Kenar D.; Ma, Lin; Lacson, Eduardo

    2016-01-01

    Background and objectives Patients on hemodialysis have a high rate of hip fractures. In this study, we performed a contemporary analysis of mineral and bone parameters and their relationship to hip and femur fracture risk. Design, setting, participants, & measurements Patients on hemodialysis treated between 2000 and 2013 in Fresenius Medical Care North America facilities were included. Predictors were on the basis of data as of December 31 of each baseline year and time-averaged values of selected laboratory parameters and medication doses throughout the year. Four period cohorts were constructed from baseline years: 2000, 2003, 2006, and 2009. Follow-up for each cohort was ≤3 years. Results The incidence of hip and femur fractures remained generally unchanged (P=0.40), except among patients who were white and >65 years of age, in whom the rate decreased significantly over the 14-year period (P<0.01). Results from combined multivariable models indicated that the lowest quartiles of time–averaged intact parathyroid hormone were independently associated with higher hip fracture risk (intact parathyroid hormone =181–272 pg/ml: hazard ratio, 1.20; 95% confidence interval [95% CI], 1.03 to 1.41 and intact parathyroid hormone <181 pg/ml: hazard ratio, 1.20; 95% CI, 1.01 to 1.44; referent third quartile, 273 to <433 pg/ml). The lowest quartile of time–averaged serum calcium was also associated with higher risk (calcium <8.7 mg/dl; hazard ratio, 1.17; 95% CI, 1.00 to 1.37) compared with the referent third quartile of 9.1 to <9.5 mg/dl. Conclusions We found an association between lower levels of intact parathyroid hormone and serum calcium and greater risk for hip and femur fractures among patients on hemodialysis. These findings support additional research toward elucidating long-term safety of treatment approaches for hyperparathyroidism in patients with ESRD. PMID:27026521

  9. Analysis on the Initial Cracking Parameters of Cross-Measure Hydraulic Fracture in Underground Coal Mines

    Directory of Open Access Journals (Sweden)

    Yiyu Lu

    2015-07-01

    Full Text Available Initial cracking pressure and locations are important parameters in conducting cross-measure hydraulic fracturing to enhance coal seam permeability in underground coalmines, which are significantly influenced by in-situ stress and occurrence of coal seam. In this study, stress state around cross-measure fracturing boreholes was analyzed using in-situ stress coordinate transformation, then a mathematical model was developed to evaluate initial cracking parameters of borehole assuming the maximum tensile stress criterion. Subsequently, the influences of in-situ stress and occurrence of coal seams on initial cracking pressure and locations in underground coalmines were analyzed using the proposed model. Finally, the proposed model was verified with field test data. The results suggest that the initial cracking pressure increases with the depth cover and coal seam dip angle. However, it decreases with the increase in azimuth of major principle stress. The results also indicate that the initial cracking locations concentrated in the second and fourth quadrant in polar coordinate, and shifted direction to the strike of coal seam as coal seam dip angle and azimuth of maximum principle stress increase. Field investigation revealed consistent rule with the developed model that the initial cracking pressure increases with the coal seam dip angle. Therefore, the proposed mathematical model provides theoretical insight to analyze the initial cracking parameters during cross-measure hydraulic fracturing for underground coalmines.

  10. [Analysis of correlation between trabecular microstructure and clinical imaging parameters in fracture region of osteoporotic hip].

    Science.gov (United States)

    Peng, Jing; Zhou, Yong; Min, Li; Zhang, Wenli; Luo, Yi; Zhang, Xuelei; Zou, Chang; Shi, Rui; Tu, Chongqi

    2014-05-01

    To analyze the correlation between the trabecular microstructure and the clinical imaging parameters in the fracture region of osteoporotic hip so as to provide a simple method to evaluate the trabecular microstructure by a non-invasive way. Between June 2012 and January 2013, 16 elderly patients with femoral neck fracture underwent hip arthroplasty were selected as the trial group; 5 young patients with pelvic fracture were selected as the control group. The hip CT examination was done, and cancellous bone volume/marrow cavity volume (CV/MV) was analyzed with Mimics 10.01 software in the control group. The CT scan and bone mineral density (BMD) measurement were performed on normal hips of the trial group, and cuboid specimens were gained from the femoral necks at the place of the tensional trabeculae to evaluate the trabecular microstructure parameters by Micro-CT, including bone volume fraction (BV/TV), trabecular number (Tb.N), trabecular spacing (Tb.Sp), trabecular thickness (Tb.Th), connect density (Conn.D), and structure model index (SMI). The correlation between imaging parameters and microstructure parameters was analyzed. In the trial group, the BMD value was 0.491-0.698 g/cm2 (mean, 0.601 g/cm2); according to World Health Organization (WHO) standard, 10 cases were diagnosed as having osteoporosis, and 6 cases as having osteopenia. The CV/MV of the trial group (0.670 1 +/- 0.102 0) was significantly lower than that of the control group (0.885 0 +/- 0.089 1) (t = -4.567, P = 0.000). In the trial group, CV/MV had correlation with BV/TV, Tb.Th, and SMI (P 0.05). BV/TV had correlation with Tb.Th, Tb.N, Tb.Sp, and SMI (P microstructure parameters (P > 0.05). CV/MV obviously decreases in the osteoporotic hip, and there is a correlation between CV/MV and the microstructure parameters of BV/TV, Tb.Th, and SMI, to some extent, which can reflect the variety of the microstructure of the trabeculae. There is no correlation between BMD of femoral neck and

  11. A combined experimental and analytical approach for interface fracture parameters of dissimilar materials in electronic packages

    International Nuclear Information System (INIS)

    Kay, N.R.; Ghosh, S.; Guven, I.; Madenci, E.

    2006-01-01

    This study concerns the development of a combined experimental and analytical technique to determine the critical values of fracture parameters for interfaces between dissimilar materials in electronic packages. This technique utilizes specimens from post-production electronic packages. The mechanical testing is performed inside a scanning electron microscope while the measurements are achieved by means of digital image correlation. The measured displacements around the crack tip are used as the boundary conditions for the analytical model to compute the energy release rate. The critical energy release rate values obtained from post-production package specimens are obtained to be lower than those laboratory specimens

  12. On conditions and parameters important to model sensitivity for unsaturated flow through layered, fractured tuff

    International Nuclear Information System (INIS)

    Prindle, R.W.; Hopkins, P.L.

    1990-10-01

    The Hydrologic Code Intercomparison Project (HYDROCOIN) was formed to evaluate hydrogeologic models and computer codes and their use in performance assessment for high-level radioactive-waste repositories. This report describes the results of a study for HYDROCOIN of model sensitivity for isothermal, unsaturated flow through layered, fractured tuffs. We investigated both the types of flow behavior that dominate the performance measures and the conditions and model parameters that control flow behavior. We also examined the effect of different conceptual models and modeling approaches on our understanding of system behavior. The analyses included single- and multiple-parameter variations about base cases in one-dimensional steady and transient flow and in two-dimensional steady flow. The flow behavior is complex even for the highly simplified and constrained system modeled here. The response of the performance measures is both nonlinear and nonmonotonic. System behavior is dominated by abrupt transitions from matrix to fracture flow and by lateral diversion of flow. The observed behaviors are strongly influenced by the imposed boundary conditions and model constraints. Applied flux plays a critical role in determining the flow type but interacts strongly with the composite-conductivity curves of individual hydrologic units and with the stratigraphy. One-dimensional modeling yields conservative estimates of distributions of groundwater travel time only under very limited conditions. This study demonstrates that it is wrong to equate the shortest possible water-travel path with the fastest path from the repository to the water table. 20 refs., 234 figs., 10 tabs

  13. Estimation of Fracture Parameters for Leak-before-Break Assessment on Elevated Temperature

    International Nuclear Information System (INIS)

    Lee, S. Y.; Kim, N. H.; Koo, G. H.; Kim, D. J.

    2015-01-01

    When the liquid sodium leaks this interaction may cause the fire that is harmful to safety of the reactor. Therefore, it is necessary to prevent against sodium fire in SFRs. Leak-before-Break(LBB) concept, had been devised for this purpose and has following advantage than Double-ended Guillotine Break(DEGB) design. If DEGB is excluded, the number of extinguish facilities and firewalls against the sodium fire can be minimize. LBB concept, has been well established and had many experience in regard of light water reactors(LWRs). But LBB assessment to SFRs is more complicated because SFRs is operated on elevated temperature region. On this region, because creep damage occurs to material and grows defects LBB assessment to SFRs should be considering creep effects. The procedure and method for this purpose are provided RCC-MRx A16 that is France code. To calculate fracture parameters such as K and J are required to some coefficients and equations which have been limited in RCC-MRx A16. Thus, in this study obtained K and J using finite element analysis for the sub-model including the crack. In this study, fracture parameters for LBB assessment were estimated by finite element analysis. This result will be applicable to LBB assessment of PGSFR

  14. Determining fracture energy parameters of concrete from the modified compact tension test

    Directory of Open Access Journals (Sweden)

    A. Fernández-Canteli

    2014-10-01

    Full Text Available The modified compact tension (MCT test, though not yet recognized as a valid test for determining fracture energy of concrete, is believed to represent a plausible and suitable alternative versus other well established procedures, such as the wedge-splitting test (WST and the three point (3PB or four point bending (4PB tests, due to its simplicity and low cost. The aim of the paper is twofold: Firstly, to demonstrate the necessary correspondence between the experimental MCT test setup and finite element simulations and secondly, to initiate the way of establishing the desirable conversion between the fracture energy parameter values resulting from the MCT test and the standard conventional procedures. MCT tests are carried out and compared with the numerical results from 2-D and 3-D finite element calculations using the commercial codes ABAQUS and ATENA, the latter being specifically developed for applications on concrete structures and elements. In this way, the usability of the modified compact tension test for practical purposes is confirmed.

  15. Crack diffusion coefficient - A candidate fracture toughness parameter for short fiber composites

    Science.gov (United States)

    Mull, M. A.; Chudnovsky, A.; Moet, A.

    1987-01-01

    In brittle matrix composites, crack propagation occurs along random trajectories reflecting the heterogeneous nature of the strength field. Considering the crack trajectory as a diffusive process, the 'crack diffusion coefficient' is introduced. From fatigue crack propagation experiments on a set of identical SEN polyester composite specimens, the variance of the crack tip position along the loading axis is found to be a linear function of the effective 'time'. The latter is taken as the effective crack length. The coefficient of proportionality between variance of the crack trajectory and the effective crack length defines the crack diffusion coefficient D which is found in the present study to be 0.165 mm. This parameter reflects the ability of the composite to deviate the crack from the energetically most efficient path and thus links fracture toughness to the microstructure.

  16. Determination of fracture parameters for interface cracks in transverse isotropic magnetoelectroelastic composites

    Directory of Open Access Journals (Sweden)

    Lei Jun

    2015-01-01

    Full Text Available To determine fracture parameters of interfacial cracks in transverse isotropic magnetoelectroelastic composites, a displacement extrapolation formula was derived. The matrix-form formula can be applicable for both material components with arbitrary poling directions. The corresponding explicit expression of this formula was obtained for each poling direction normal to the crack plane. This displacement extrapolation formula is only related to the boundary quantities of the extended crack opening displacements across crack faces, which is convenient for numerical applications, especially for BEM. Meantime, an alternative extrapolation formula based on the path-independent J-integral and displacement ratios was presented which may be more adaptable for any domain-based numerical techniques like FEM. A numerical example was presented to show the correctness of these formulae.

  17. Numerical Evaluation and Optimization of Multiple Hydraulically Fractured Parameters Using a Flow-Stress-Damage Coupled Approach

    Directory of Open Access Journals (Sweden)

    Yu Wang

    2016-04-01

    Full Text Available Multiple-factor analysis and optimization play a critical role in the the ability to maximizethe stimulated reservoir volume (SRV and the success of economic shale gas production. In this paper, taking the typical continental naturally fractured silty laminae shale in China as anexample, response surface methodology (RSM was employed to optimize multiple hydraulic fracturing parameters to maximize the stimulated area in combination with numerical modeling based on the coupled flow-stress-damage (FSD approach. This paper demonstrates hydraulic fracturing effectiveness by defining two indicesnamelythe stimulated reservoir area (SRA and stimulated silty laminae area (SLA. Seven uncertain parameters, such as laminae thickness, spacing, dip angle, cohesion, internal friction angle (IFA, in situ stress difference (SD, and an operational parameter-injection rate (IR with a reasonable range based on silty Laminae Shale, Southeastern Ordos Basin, are used to fit a response of SRA and SLA as the objective function, and finally identity the optimum design under the parameters based on simultaneously maximizingSRA and SLA. In addition, asensitivity analysis of the influential factors is conducted for SRA and SLA. The aim of the study is to improve the artificial ability to control the fracturing network by means of multi-parameteroptimization. This work promises to provide insights into the effective exploitation of unconventional shale gas reservoirs via optimization of the fracturing design for continental shale, Southeastern Ordos Basin, China.

  18. Halogenation of Hydraulic Fracturing Additives in the Shale Well Parameter Space

    Science.gov (United States)

    Sumner, A. J.; Plata, D.

    2017-12-01

    Horizontal Drilling and Hydraulic fracturing (HDHF) involves the deep-well injection of a `fracking fluid' composed of diverse and numerous chemical additives designed to facilitate the release and collection of natural gas from shale plays. The potential impacts of HDHF operations on water resources and ecosystems are numerous, and analyses of flowback samples revealed organic compounds from both geogenic and anthropogenic sources. Furthermore, halogenated chemicals were also detected, and these compounds are rarely disclosed, suggesting the in situ halogenation of reactive additives. To test this transformation hypothesis, we designed and operated a novel high pressure and temperature reactor system to simulate the shale well parameter space and investigate the chemical reactivity of twelve commonly disclosed and functionally diverse HDHF additives. Early results revealed an unanticipated halogenation pathway of α-β unsaturated aldehyde, Cinnamaldehyde, in the presence of oxidant and concentrated brine. Ongoing experiments over a range of parameters informed a proposed mechanism, demonstrating the role of various shale-well specific parameters in enabling the demonstrated halogenation pathway. Ultimately, these results will inform a host of potentially unintended interactions of HDHF additives during the extreme conditions down-bore of a shale well during HDHF activities.

  19. Experimental and computational correlation of fracture parameters KIc, JIc, and GIc for unimodular and bimodular graphite components

    Science.gov (United States)

    Bhushan, Awani; Panda, S. K.

    2018-05-01

    The influence of bimodularity (different stress ∼ strain behaviour in tension and compression) on fracture behaviour of graphite specimens has been studied with fracture toughness (KIc), critical J-integral (JIc) and critical strain energy release rate (GIc) as the characterizing parameter. Bimodularity index (ratio of tensile Young's modulus to compression Young's modulus) of graphite specimens has been obtained from the normalized test data of tensile and compression experimentation. Single edge notch bend (SENB) testing of pre-cracked specimens from the same lot have been carried out as per ASTM standard D7779-11 to determine the peak load and critical fracture parameters KIc, GIc and JIc using digital image correlation technology of crack opening displacements. Weibull weakest link theory has been used to evaluate the mean peak load, Weibull modulus and goodness of fit employing two parameter least square method (LIN2), biased (MLE2-B) and unbiased (MLE2-U) maximum likelihood estimator. The stress dependent elasticity problem of three-dimensional crack progression behaviour for the bimodular graphite components has been solved as an iterative finite element procedure. The crack characterizing parameters critical stress intensity factor and critical strain energy release rate have been estimated with the help of Weibull distribution plot between peak loads versus cumulative probability of failure. Experimental and Computational fracture parameters have been compared qualitatively to describe the significance of bimodularity. The bimodular influence on fracture behaviour of SENB graphite has been reflected on the experimental evaluation of GIc values only, which has been found to be different from the calculated JIc values. Numerical evaluation of bimodular 3D J-integral value is found to be close to the GIc value whereas the unimodular 3D J-value is nearer to the JIc value. The significant difference between the unimodular JIc and bimodular GIc indicates that

  20. Tracer SWIW tests in propped and un-propped fractures: parameter sensitivity issues, revisited

    Science.gov (United States)

    Ghergut, Julia; Behrens, Horst; Sauter, Martin

    2017-04-01

    Single-well injection-withdrawal (SWIW) or 'push-then-pull' tracer methods appear attractive for a number of reasons: less uncertainty on design and dimensioning, and lower tracer quantities required than for inter-well tests; stronger tracer signals, enabling easier and cheaper metering, and shorter metering duration required, reaching higher tracer mass recovery than in inter-well tests; last not least: no need for a second well. However, SWIW tracer signal inversion faces a major issue: the 'push-then-pull' design weakens the correlation between tracer residence times and georeservoir transport parameters, inducing insensitivity or ambiguity of tracer signal inversion w. r. to some of those georeservoir parameters that are supposed to be the target of tracer tests par excellence: pore velocity, transport-effective porosity, fracture or fissure aperture and spacing or density (where applicable), fluid/solid or fluid/fluid phase interface density. Hydraulic methods cannot measure the transport-effective values of such parameters, because pressure signals correlate neither with fluid motion, nor with material fluxes through (fluid-rock, or fluid-fluid) phase interfaces. The notorious ambiguity impeding parameter inversion from SWIW test signals has nourished several 'modeling attitudes': (i) regard dispersion as the key process encompassing whatever superposition of underlying transport phenomena, and seek a statistical description of flow-path collectives enabling to characterize dispersion independently of any other transport parameter, as proposed by Gouze et al. (2008), with Hansen et al. (2016) offering a comprehensive analysis of the various ways dispersion model assumptions interfere with parameter inversion from SWIW tests; (ii) regard diffusion as the key process, and seek for a large-time, asymptotically advection-independent regime in the measured tracer signals (Haggerty et al. 2001), enabling a dispersion-independent characterization of multiple

  1. Linear least squares approach for evaluating crack tip fracture parameters using isochromatic and isoclinic data from digital photoelasticity

    Science.gov (United States)

    Patil, Prataprao; Vyasarayani, C. P.; Ramji, M.

    2017-06-01

    In this work, digital photoelasticity technique is used to estimate the crack tip fracture parameters for different crack configurations. Conventionally, only isochromatic data surrounding the crack tip is used for SIF estimation, but with the advent of digital photoelasticity, pixel-wise availability of both isoclinic and isochromatic data could be exploited for SIF estimation in a novel way. A linear least square approach is proposed to estimate the mixed-mode crack tip fracture parameters by solving the multi-parameter stress field equation. The stress intensity factor (SIF) is extracted from those estimated fracture parameters. The isochromatic and isoclinic data around the crack tip is estimated using the ten-step phase shifting technique. To get the unwrapped data, the adaptive quality guided phase unwrapping algorithm (AQGPU) has been used. The mixed mode fracture parameters, especially SIF are estimated for specimen configurations like single edge notch (SEN), center crack and straight crack ahead of inclusion using the proposed algorithm. The experimental SIF values estimated using the proposed method are compared with analytical/finite element analysis (FEA) results, and are found to be in good agreement.

  2. Correlation between Parameters of Calcaneal Quantitative Ultrasound and Hip Structural Analysis in Osteoporotic Fracture Patients.

    Directory of Open Access Journals (Sweden)

    Licheng Zhang

    Full Text Available Calcaneal quantitative ultrasound (QUS, which is used in the evaluation of osteoporosis, is believed to be intimately associated with the characteristics of the proximal femur. However, the specific associations of calcaneal QUS with characteristics of the hip sub-regions remain unclear.A cross-sectional assessment of 53 osteoporotic patients was performed for the skeletal status of the heel and hip.We prospectively enrolled 53 female osteoporotic patients with femoral fractures. Calcaneal QUS, dual energy X-ray absorptiometry (DXA, and hip structural analysis (HSA were performed for each patient. Femoral heads were obtained during the surgery, and principal compressive trabeculae (PCT were extracted by a three-dimensional printing technique-assisted method. Pearson's correlation between QUS measurement with DXA, HSA-derived parameters and Young's modulus were calculated in order to evaluate the specific association of QUS with the parameters for the hip sub-regions, including the femoral neck, trochanteric and Ward's areas, and the femoral shaft, respectively.Significant correlations were found between estimated BMD (Est.BMD and BMD of different sub-regions of proximal femur. However, the correlation coefficient of trochanteric area (r = 0.356, p = 0.009 was higher than that of the neck area (r = 0.297, p = 0.031 and total proximal femur (r = 0.291, p = 0.034. Furthermore, the quantitative ultrasound index (QUI was significantly correlated with the HSA-derived parameters of the trochanteric area (r value: 0.315-0.356, all p<0.05 as well as with the Young's modulus of PCT from the femoral head (r = 0.589, p<0.001.The calcaneal bone had an intimate association with the trochanteric cancellous bone. To a certain extent, the parameters of the calcaneal QUS can reflect the characteristics of the trochanteric area of the proximal hip, although not specifically reflective of those of the femoral neck or shaft.

  3. The effect of rotational deformity on patellofemoral parameters following the treatment of femoral shaft fracture.

    Science.gov (United States)

    Yildirim, Ahmet Ozgur; Aksahin, Ertuğrul; Sakman, Bulent; Kati, Yusuf Alper; Akti, Sefa; Dogan, Ozgur; Ucaner, Ahmet; Bicimoglu, Ali

    2013-05-01

    The purpose of this study was to investigate the effect of rotational deformities on patellofemoral alignment using the dynamic magnetic resonance imaging method on patients whose femur fractures were treated with intramedullary locking nails. The dynamic patellofemoral magnetic resonance imaging results of 33 patients (5 females and 28 males) were reviewed. The mean age of the patients was 36.3 (range 19-61) years. The mean follow-up was 30.2 months (range 24-38). All the patients were given Kujala patellofemoral clinical evaluation scores at the latest follow-up. Those with less than 10° of rotational deformity in either direction were classified as Group A, those with more than a 10° of internal rotation deformity as Group B and more than a 10° of external rotation deformity as Group C. The three groups were then compared regarding to clinical scores. Patellofemoral parameters of operated and contralateral side were also compared in each group. There were 14 (42.4 %) patients in Group A, 12 (36.4 %) patients in Group B and 7 (21.2 %) patients in Group C. The mean patella score in Group C (74 ± 7.02) was significantly lower when compared with Group B (87.6 ± 9.9) and group A (90.6 ± 6.1) (p < 0.05). In Group C patients, medial patellar tilt was detected when compared with the intact side. There were no significant changes in patellofemoral position in either Group A or Group B. The results of this study revealed that more than 10° of external rotation deformity could cause a detoriation in the patellofemoral scores. Anatomic reduction of the fracture site should be performed as soon as possible and external rotational deformities should especially be avoided in order to prevent patellofemoral malalignment.

  4. The Effect of Diode Laser With Different Parameters on Root Fracture During Irrigation Procedure.

    Science.gov (United States)

    Karataş, Ertuğrul; Arslan, Hakan; Topçuoğlu, Hüseyin Sinan; Yılmaz, Cenk Burak; Yeter, Kübra Yesildal; Ayrancı, Leyla Benan

    2016-06-01

    The aim of this study is to compare the effect of a single diode laser application and agitation of EDTA with diode laser with different parameters at different time intervals on root fracture. Ninety mandibular incisors were instrumented except the negative control group. The specimens were divided randomly into 10 groups according to final irrigation procedure: (G1) non-instrumented; (G2) distilled water; (G3) 15% EDTA; (G4) ultrasonically agitated EDTA; (G5) single 1.5W/100 Hz Diode laser; (G6) single 3W/100 Hz Diode laser; (G7) 1.5W/100 Hz Diode laser agitation of EDTA for 20 s; (G8) 1.5W/100 Hz Diode laser agitation of EDTA for 40 s; (G9) 3W/100 Hz Diode laser agitation of EDTA for 20 s; and (G10) 3W/100 Hz Diode laser agitation of EDTA for 40 s. The specimens were filled, mounted in acrylic resin, and compression strength test was performed on each specimen. Statistical analysis was carried out using one way ANOVA and Tukey's post hoc tests (P = 0.05). The statistical analysis revealed that there were statistically significant differences among the groups (P Laser-agitated irrigation with a 3W/100 Hz Diode laser for both 20 s and 40 s decreased the fracture resistance of teeth. Copyright © 2015 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  5. Estimation of the crack propagation direction in a mixed-mode geometry via multi-parameter fracture criteria

    Czech Academy of Sciences Publication Activity Database

    Malíková, L.; Veselý, V.; Seitl, Stanislav

    2015-01-01

    Roč. 9, č. 33 (2015), s. 25-32 ISSN 1971-8993 Institutional support: RVO:68081723 Keywords : Near-crack-tip fields * Williams expansion * Crack propagation direction * Multi-parameter fracture criteria * Finite element analysis Subject RIV: JL - Materials Fatigue, Friction Mechanics

  6. The effect of water to cement ratio on fracture parameters and brittleness of self-compacting concrete

    International Nuclear Information System (INIS)

    Beygi, Morteza H.A.; Kazemi, Mohammad T.; Nikbin, Iman M.; Amiri, Javad. Vaseghi

    2013-01-01

    Highlights: ► Fracture properties of SCC were obtained using two different methods. ► Results showed with decrease of w/c ratio the fracture toughness increases. ► Size effect method can predict the peak load with a good precision for SCC beams. ► The size effect curve showed SCC ductility increases with increase of w/c ratio. - Abstract: The paper describes an experimental research on fracture characteristics of self-compacting concrete (SCC). Three point bending tests conducted on 154 notched beams with different water to cement (w/c) ratios. The specimens were made from mixes with various w/c ratios from 0.7 to 0.35. For all mixes, common fracture parameters were determined using two different methods, the work-of-fracture method (WFM) and the size effect method (SEM). Test results showed that with decrease of w/c ratio from 0.7 to 0.35 in SCC: (a) the fracture toughness increases linearly: (b) the brittleness number is approximately doubled: (c) the effective size of the process zone c f in SEM and the characteristic length (l ch ) in WFM decrease which may be explained by the change in structural porosity of the aggregate–paste transition zone; and (d) the fracture surface of concrete is roughly smoother, which can be attributed to the improved bond strength between the aggregates and the paste. Also, the results showed that there is a correlation between the fracture energy measured by WFM (G F ) and the value measured through SEM (G f ) (G F ≅ 2.92G f )

  7. Quantitative ultrasound parameters as well as bone mineral density are better predictors of trochanteric than cervical hip fractures in elderly women. Results from the EPIDOS study.

    Science.gov (United States)

    Schott, A M; Hans, D; Duboeuf, F; Dargent-Molina, P; Hajri, T; Bréart, G; Meunier, P J

    2005-12-01

    Hip fractures can be separated into cervical and trochanteric fractures. Trochanteric fractures have been associated with up to twice the short-term mortality of cervical fractures in the elderly. There is also evidence suggesting that the mechanisms are different. Evidence from the literature remains limited on the predictive power of bone mineral density (BMD) and quantitative ultrasounds (QUS) for both types of hip fractures. 5703 elderly women aged 75 years or more, who were recruited from the voting lists in the EPIDOS study, and had baseline calcaneal ultrasounds (QUS) and DXA measurements at the hip and the whole body, were analyzed in this paper. Among those, 192 hip fractures occurred during an average follow-up of 4 years, 108 cervical and 84 trochanteric fractures. Femoral neck, trochanteric and whole body BMD were able to predict trochanteric hip fracture (RR's and 95% CI were, respectively, 3.2 (2.4-4.2); 4.8 (3.5-6.6); and 2.8 (2.2-3.6)) more accurately than cervical fractures (respectively, 2.1 (1.7-2.7); 2.3 (1.8-3.0); 1.2 (1.0-1.6)). All ultrasound parameters, SOS, BUA, and stiffness index (SI) were significant predictors of trochanteric (RR's respectively 3.0 (2.2-4.1), 2.5(2.0-3.1), and 3.5(2.6-4.7)) but not cervical fractures. After adjustment for femoral neck or trochanteric BMD ultrasound parameters were still significant predictors of trochanteric fracture, and stiffness tended to be a better predictor of trochanteric fractures than either BUA or SOS with a relative risk of 2.25 (1.6-3.1). A significant decrease of all bone measurements, BMD and QUS, was highly predictive of trochanteric fractures, whereas a decrease of femoral neck and trochanteric BMD were only associated with a slight increase in cervical fracture risk and a low total body BMD or QUS parameters were not significant predictors of cervical fractures. In women who sustained a hip fracture, the decrease of BMD and QUS values increases the risk of trochanteric fracture as

  8. Correlation of nodular austempered ductile iron (ADI) microstructural parameters and fatigue properties using an approach based on fracture mechanics

    International Nuclear Information System (INIS)

    Dias, Jose Felipe; Fonseca, Vinicius Rizzuti; Godefroid, Leonardo Barbosa; Ribeiro, Gabriel de Oliveira

    2010-01-01

    An investigation has been accomplished to check the effect of temperature and austempering time on austempered ductile iron (ADI) properties by means of fracture toughness (K_C) and fatigue threshold (∆K_t_h) tests. The correlation of ADI microstructural parameters and ADI two mechanical parameters: KC and Kth, is evaluated. Three sets of samples have ben extracted from ADI casting Y blocks produced in industrial conditions.and austenitized at 900°C for 1.5 hour. The austempering process has been performed in the following ways: the first set was austenitized at 300 deg C for 4 hours, the second set at 360°C for 1.5 hour and the third at 360°C for 0.6 hour. These distinct austempering processes have been adopted in order to obtain distinct microstructures containing austenite with two different carbon rates and two ferritic cell sizes. The materials have been characterized by means of optical and electronic microscopy, X-ray diffraction and mechanical tests. All materials have presented equivalent fatigue crack propagation rates, fracture toughness in the range between 94 and 128 MPa·m"1"/"2 and ∆K_t_h in the range between 5,7 and 6,4 MPa·m"1"/"2. The experimental results have confirmed the effect of microstructural properties (austenitic volumetric rate, austenitic carbon rate, ferritic cell size, total matrix carbon content) on fracture toughness (K_C) and fatigue threshold (∆K_t_h). Further, it was found that following parameters: fracture toughness (K_C), fatigue threshold ((∆K_t_h) and impact strength are correlated with the total matrix carbon content and ferritic cell size. (author)

  9. Parameters controlling fracturing distribution: example of an Upper Jurassic marly-calcareous formation (eastern Paris Basin)

    International Nuclear Information System (INIS)

    Andre, G.; Rebours, H.; Wileveau, Y.; Proudhon, B.

    2006-01-01

    Study of fractures along a 490-m vertical section of marl/limestone alternations in the Upper Jurassic (Meuse/Haute-Marne underground research laboratory-eastern Paris Basin) reveals their organization and the different states of palaeo-stress. Type and extension of tectonic structures seem to be controlled principally by lithology and secondary by depth. Also, it appears deviations of Alpine palaeo-stresses between Kimmeridgian and Oxfordian formations. These deviations are related to the presence of marl/limestone contacts. The vertical evolution of current horizontal maximum stress shows a similar behaviour, with deviations at the walls of Callovo-Oxfordian argilites. These results allow us to point out and to discuss the impact of lithology, rheology and depth on fracturing occurrence and distribution. Furthermore, this study suggests the role of Callovo-Oxfordian as a barrier for fracture development between the limestones of Dogger and Oxfordian formations. (authors)

  10. Overview of input parameters for calculation of the probability of a brittle fracture of the reactor pressure vessel

    International Nuclear Information System (INIS)

    Horacek, L.

    1994-12-01

    The parameters are summarized for a calculation of the probability of brittle fracture of the WWER-440 reactor pressure vessel (RPV). The parameters were selected for 2 basic approaches, viz., one based on the Monte Carlo method and the other on the FORM and SORM methods (First and Second Order Reliability Methods). The approaches were represented by US computer codes VISA-II and OCA-P and by the German ZERBERUS code. The philosophy of the deterministic and probabilistic aspects of the VISA-II code is outlined, and the differences between the US and Czech PWR's are discussed in this context. Briefly described is the partial approach to the evaluation of the WWER type RPV's based on the assessment of their resistance to brittle fracture by fracture mechanics tools and by using the FORM and SORM methods. Attention is paid to the input data for the WWER modification of the VISA-II code. The data are categorized with respect to randomness, i.e. to the stochastic or deterministic nature of their behavior. 18 tabs., 14 refs

  11. Determining fracture energy parameters of concrete from the modified compact tension test

    Czech Academy of Sciences Publication Activity Database

    Canteli, A.; Castañón, L.; Nieto, B.; Lozano, M.; Holušová, Táňa; Seitl, Stanislav

    2014-01-01

    Roč. 30, OCT (2014), s. 383-393 ISSN 1971-8993 R&D Projects: GA MŠk(CZ) EE2.3.20.0214 Grant - others:interní podpora AV ČR(CZ) M100411204 Institutional support: RVO:68081723 Keywords : Concrete fracture energy * Modified compact tension test * Concrete * Numerical simulation Subject RIV: JL - Materials Fatigue, Friction Mechanics

  12. The influence of physical activity and fractures on ultrasound parameters in elderly people

    NARCIS (Netherlands)

    Graafmans, W.C.; Bouter, L.M.; Lips, P.T.A.M.

    1998-01-01

    In this cross-sectional study we investigated the relationship between ultrasound measurements in the calcaneus versus daily physical activity and fractures sustained in the past in elderly subjects. Ultrasound measurements were performed at both heels, which enabled us to examine determinants of

  13. Laboratory mechanical parameters of composite resins and their relation to fractures and wear in clinical trials-A systematic review.

    Science.gov (United States)

    Heintze, Siegward D; Ilie, Nicoleta; Hickel, Reinhard; Reis, Alessandra; Loguercio, Alessandro; Rousson, Valentin

    2017-03-01

    To evaluate a range of mechanical parameters of composite resins and compare the data to the frequency of fractures and wear in clinical studies. Based on a search of PubMed and SCOPUS, clinical studies on posterior composite restorations were investigated with regard to bias by two independent reviewers using Cochrane Collaboration's tool for assessing risk of bias in randomized trials. The target variables were chipping and/or fracture, loss of anatomical form (wear) and a combination of both (summary clinical index). These outcomes were modelled by time and material in a linear mixed effect model including random study and experiment effects. The laboratory data from one test institute were used: flexural strength, flexural modulus, compressive strength, and fracture toughness (all after 24-h storage in distilled water). For some materials flexural strength data after aging in water/saliva/ethanol were available. Besides calculating correlations between clinical and laboratory outcomes, we explored whether a model including a laboratory predictor dichotomized at a cut-off value better predicted a clinical outcome than a linear model. A total of 74 clinical experiments from 45 studies were included involving 31 materials for which laboratory data were also available. A weak positive correlation between fracture toughness and clinical fractures was found (Spearman rho=0.34, p=0.11) in addition to a moderate and statistically significant correlation between flexural strength and clinical wear (Spearman rho=0.46, p=0.01). When excluding those studies with "high" risk of bias (n=18), the correlations were generally weaker with no statistically significant correlation. For aging in ethanol, a very strong correlation was found between flexural strength decrease and clinical index, but this finding was based on only 7 materials (Spearman rho=0.96, p=0.0001). Prediction was not consistently improved with cutoff values. Correlations between clinical and laboratory

  14. A numerical study of two different specimen fixtures for the modified compact tension test – their influence on concrete fracture parameters

    Czech Academy of Sciences Publication Activity Database

    Holušová, Táňa; Seitl, Stanislav; Cifuentes, H.; Canteli, A.

    2016-01-01

    Roč. 10, č. 35 (2016), s. 242-249 ISSN 1971-8993 Institutional support: RVO:68081723 Keywords : Modified Compact Tension Test * Fracture Parameters * Cementitious Composites * FEM Subject RIV: JL - Materials Fatigue, Friction Mechanics

  15. A two-parameter model to predict fracture in the transition

    International Nuclear Information System (INIS)

    DeAquino, C.T.; Landes, J.D.; McCabe, D.E.

    1995-01-01

    A model is proposed that uses a numerical characterization of the crack tip stress field modified by the J - Q constraint theory and a weak link assumption to predict fracture behavior in the transition for reactor vessel steels. This model predicts the toughness scatter band for a component model from a toughness scatter band measured on a test specimen geometry. The model has been applied previously to two-dimensional through cracks. Many applications to actual components structures involve three-dimensional surface flaws. These cases require a more difficult level of analysis and need additional information. In this paper, both the current model for two-dimensional cracks and an approach needed to extend the model for the prediction of transition fracture behavior in three-dimensional surface flaws are discussed. Examples are presented to show how the model can be applied and in some cases to compare with other test results. (author). 13 refs., 7 figs

  16. The generalized fracture criteria based on the multi-parameter representation of the crack tip stress field

    Science.gov (United States)

    Stepanova, L. V.

    2017-12-01

    The paper is devoted to the multi-parameter asymptotic description of the stress field near the crack tip of a finite crack in an infinite isotropic elastic plane medium subject to 1) tensile stress; 2) in-plane shear; 3) mixed mode loading for a wide range of mode-mixity situations (Mode I and Mode II). The multi-parameter series expansion of stress tensor components containing higher-order terms is obtained. All the coefficients of the multiparameter series expansion of the stress field are given. The main focus is on the discussion of the influence of considering the higher-order terms of the Williams expansion. The analysis of the higher-order terms in the stress field is performed. It is shown that the larger the distance from the crack tip, the more terms it is necessary to keep in the asymptotic series expansion. Therefore, it can be concluded that several more higher-order terms of the Williams expansion should be used for the stress field description when the distance from the crack tip is not small enough. The crack propagation direction angle is calculated. Two fracture criteria, the maximum tangential stress criterion and the strain energy density criterion, are used. The multi-parameter form of the two commonly used fracture criteria is introduced and tested. Thirty and more terms of the Williams series expansion for the near-crack-tip stress field enable the angle to be calculated more precisely.

  17. Estimation of hydrodinamics parameters in a volcanic fractured phreatic aquifer in Costa Rica. Part II. Double porosity model

    International Nuclear Information System (INIS)

    Macias, Julio; Vargas, Asdrubal

    2017-01-01

    MIM 1D transport model was successfully applied to simulate the asymmetric behavior observed in three breakthrough curves of tracer tests performed under natural gradient conditions in a phreatic fractured volcanic aquifer. The transport parameters obtained after adjustment with a computer program, suggest that only 50% of the total porosity effectively contributed to the advective-dispersive transport (mobile fraction) and the other 50% behaved as a temporary reservoir for the tracer (immobile fraction). The estimated values of hydraulic properties and MIM model parameters are within the range of values reported by other researchers. It was possible to establish a conceptual and numerical framework to explain the three-tracer tests curves behavior, despite the limitations in quality and quantity of available field information. (author) [es

  18. Influences of process parameters and microstructure on the fracture mechanisms of ODS steels

    International Nuclear Information System (INIS)

    Rouffié, A.L.; Wident, P.; Ziolek, L.; Delabrouille, F.; Tanguy, B.; Crépin, J.; Pineau, A.; Garat, V.; Fournier, B.

    2013-01-01

    The present work investigates the impact response of three ODS steels containing 9%Cr and 14%Cr. These steels were produced by hot extrusion in the shapes of a rod and a plate. The 9%Cr ODS steel has a quasi-isotropic microstructure and is given as a reference material. In comparison, the 14%Cr ODS steel has a strong morphological and crystallographic texture given by the process route. The impact behaviour is anisotropic and the fracture energies are higher when the material is tested in the longitudinal direction compared to the transverse direction. Moreover, the 14%Cr ODS steel has a better impact behaviour when it is extruded in the shape of a rod rather than in the shape of a plate. This work focuses on the fracture mechanisms involved in the ductile to brittle transition regime and in the brittle regime of these materials. In the case of the 14%Cr ODS steel, the cleavage facets observed at very low temperature are much larger than the actual size of the grains. Packets of grains with less than 15° of internal misorientation were defined as effective grains for cleavage. In the transition range, the texture enhances intergranular delamination on the 14%Cr rod material. The occurrence of delamination consumes a lot of energy and tends to enhance scattering in impact energies

  19. Influences of process parameters and microstructure on the fracture mechanisms of ODS steels

    Energy Technology Data Exchange (ETDEWEB)

    Rouffié, A.L., E-mail: anne-laure.rouffie@cea.fr [CEA, DEN, DANS, DMN, SRMA, Bât 453, F-91191 Gif-sur-Yvette (France); Wident, P.; Ziolek, L. [CEA, DEN, DANS, DMN, SRMA, Bât 453, F-91191 Gif-sur-Yvette (France); Delabrouille, F. [EDF – EDF R and D, Département MMC groupe Métallurgie, 77818 Moret sur Loing (France); Tanguy, B. [CEA, DEN, DANS, DMN, SEMI, Bât 625, F-91191 Gif-sur-Yvette (France); Crépin, J.; Pineau, A. [Mines ParisTech, Centre des Matériaux PM Fourt, UMR CNRS 7633, BP 87, 91003 Evry (France); Garat, V. [AREVA NP, 10 rue J. Récamier, 69006 Lyon (France); Fournier, B. [Manoir Industries, Metallurgy Dept., 12 rue des Ardennes, BP 8401 Pîtres, 27108 Val de Reuil Cedex (France)

    2013-02-15

    The present work investigates the impact response of three ODS steels containing 9%Cr and 14%Cr. These steels were produced by hot extrusion in the shapes of a rod and a plate. The 9%Cr ODS steel has a quasi-isotropic microstructure and is given as a reference material. In comparison, the 14%Cr ODS steel has a strong morphological and crystallographic texture given by the process route. The impact behaviour is anisotropic and the fracture energies are higher when the material is tested in the longitudinal direction compared to the transverse direction. Moreover, the 14%Cr ODS steel has a better impact behaviour when it is extruded in the shape of a rod rather than in the shape of a plate. This work focuses on the fracture mechanisms involved in the ductile to brittle transition regime and in the brittle regime of these materials. In the case of the 14%Cr ODS steel, the cleavage facets observed at very low temperature are much larger than the actual size of the grains. Packets of grains with less than 15° of internal misorientation were defined as effective grains for cleavage. In the transition range, the texture enhances intergranular delamination on the 14%Cr rod material. The occurrence of delamination consumes a lot of energy and tends to enhance scattering in impact energies.

  20. Effect of analgesia on the changes in respiratory parameters in blunt chest injury with multiple rib fractures.

    Science.gov (United States)

    Ekpe, Eyo Effiong; Eyo, Catherine

    2017-01-01

    Blunt chest injury with multiple rib fractures can result in such complications as pneumonia, atelectasis, bronchiectasis, empyema thoracis, acute respiratory distress syndrome, and prolonged Intensive Care Unit and hospital stay, with its concomitant mortality. These may be prevented or reduced by good analgesic therapy which is the subject of this study. This was a prospective study of effects of analgesia on changes in pulmonary functions of patients with traumatic multiple rib fractures resulting from blunt chest injury. There were 64 adult patients who were studied with multiple rib fractures caused by blunt chest trauma. Of these patients, 54 (84.4%) were male and 10 (15.6%) were female. Motorcycle (popularly known as "okada") and tricycle (popularly known as keke napep) accidents significantly accounted for the majority of the multiple rib fractures, that is, in 50 (78.1%) of the patients. Before analgesic administration, no patient had a normal respiratory rate, but at 1 h following the administration of analgesic, 21 (32.8%) of patients recorded normal respiratory rates and there was a significant reduction in the number (10.9% vs. 39.1%) of patients with respiratory rates> 30 breaths/min. Before commencement of analgesic, no patient recorded up to 99% of oxygen saturation (SpO2) as measured by pulse oximeter, while 43.8% recorded SpO2of 96%. This improved after 1 h of administration of analgesics to SpO2of 100% in 18.8% of patients and 99% in 31.3% of patients and none recording SpO2of 100% of predicted while only 9 (14.1%) patients were able to achieve a PEFR value in the range of 91%-100% of predicted value. One hour after analgesia, a total of 6 (9.4%) patients were able to achieve PEFR values> 100% predicted, while 35 (54.7%) patients achieved PEFR values in the range of 91%-100% predicted. Adequate analgesia is capable of reversing the negative effects of chest pain of traumatic multiple rib fractures on pulmonary function parameters through

  1. Determination of Fracture Parameters for Multiple Cracks of Laminated Composite Finite Plate

    Science.gov (United States)

    Srivastava, Amit Kumar; Arora, P. K.; Srivastava, Sharad Chandra; Kumar, Harish; Lohumi, M. K.

    2018-04-01

    A predictive method for estimation of stress state at zone of crack tip and assessment of remaining component lifetime depend on the stress intensity factor (SIF). This paper discusses the numerical approach for prediction of first ply failure load (FL), progressive failure load, SIF and critical SIF for multiple cracks configurations of laminated composite finite plate using finite element method (FEM). The Hashin and Chang failure criterion are incorporated in ABAQUS using subroutine approach user defined field variables (USDFLD) for prediction of progressive fracture response of laminated composite finite plate, which is not directly available in the software. A tensile experiment on laminated composite finite plate with stress concentration is performed to validate the numerically predicted subroutine results, shows excellent agreement. The typical results are presented to examine effect of changing the crack tip distance (S), crack offset distance (H), and stacking fiber angle (θ) on FL, and SIF .

  2. Residual stress effects on the K parameter of the fracture mechanics

    International Nuclear Information System (INIS)

    Soares, Maria da Conceiccao B. Vieira; Andrade, Arnaldo H. Paes de

    1996-01-01

    Compressive residual stresses are beneficial and improve resistance to fracture and crack growth. Residual stresses can be introduced in fabricated components by a variety of means and a number of methods such as laser surface treatment, cold expanded hole, and shot peening. Neutrons diffraction measurements of residual stress were performed at a pulsed neutron source (ISIS, Didcot, UK), on shot peened plates of nickel base superalloy Udimet 720 and titanium alloy IMI 834. The stress intensity factor (K) of residual stress was evaluated by finite element modeling and weight function method. Finite element modeling of a 2D plate with a single edge-notch was applied and, due to symmetry only half of the plate was actually modeled. The stress intensity factor (K) was evaluated for both case of remote tension stress and residual stress. Crack surface overlapping, which is physically unacceptable, was noted for small cracks under residual and boundary lading. Overlap correction was proposed and applied in order to obtain reliable values for (K). (author)

  3. A study on the evaluation for dynamic fracture mechanics parameters of viscoelastic materials by impact bending

    International Nuclear Information System (INIS)

    Sim, Jae Ki; Cho, Kyu Jac

    1988-01-01

    In this paper We derived simple formulas for the dynamic strain intensity factor by means of the Timoshenko's beam theory including the influence of rotary inertia and shear deformation on the three-point viscoelastic bend specimen. Also the contact force between the specimen and the impactor is estimated by appling the nonlinear integral equation and the Hertz's theory to the local deformation near the contact point. The results obtained from this study are as follow : 1. Analysis results of this paper, base on Timoshenko's beam theory, were more accuracy than that of Euler-Bernouli beam theory and it can be confirmed by comparsion the results with experimental results. 2. Hertz's contact thepry is static one, but it is proved that by the solution of dynamic strain intensity factor it can be applied for the case of dynamic one. 3. It is founded that the fracture mechanics paraments are overestimatimated if the effects of rotary inertia and transverse shear deformation of specimen are negleted. (Author)

  4. Prediction of the time course of callus stiffness as a function of mechanical parameters in experimental rat fracture healing studies--a numerical study.

    Directory of Open Access Journals (Sweden)

    Tim Wehner

    Full Text Available Numerous experimental fracture healing studies are performed on rats, in which different experimental, mechanical parameters are applied, thereby prohibiting direct comparison between each other. Numerical fracture healing simulation models are able to predict courses of fracture healing and offer support for pre-planning animal experiments and for post-hoc comparison between outcomes of different in vivo studies. The aims of this study are to adapt a pre-existing fracture healing simulation algorithm for sheep and humans to the rat, to corroborate it using the data of numerous different rat experiments, and to provide healing predictions for future rat experiments. First, material properties of different tissue types involved were adjusted by comparing experimentally measured callus stiffness to respective simulated values obtained in three finite element (FE models. This yielded values for Young's moduli of cortical bone, woven bone, cartilage, and connective tissue of 15,750 MPa, 1,000 MPa, 5 MPa, and 1 MPa, respectively. Next, thresholds in the underlying mechanoregulatory tissue differentiation rules were calibrated by modifying model parameters so that predicted fracture callus stiffness matched experimental data from a study that used rigid and flexible fixators. This resulted in strain thresholds at higher magnitudes than in models for sheep and humans. The resulting numerical model was then used to simulate numerous fracture healing scenarios from literature, showing a considerable mismatch in only 6 of 21 cases. Based on this corroborated model, a fit curve function was derived which predicts the increase of callus stiffness dependent on bodyweight, fixation stiffness, and fracture gap size. By mathematically predicting the time course of the healing process prior to the animal studies, the data presented in this work provides support for planning new fracture healing experiments in rats. Furthermore, it allows one to transfer and

  5. Parameters and a magnitude moment relationship from small earthquakes observed during hydraulic fracturing experiments in crystalline rocks

    Energy Technology Data Exchange (ETDEWEB)

    Pearson, C.

    1982-04-01

    Using source parameters estimated from seismic spectra and magnitudes estimated from coda lengths, we demonstrate that the log-linear relationship between moment and magnitude holds for events with magnitudes as low as -6. Using, as a data set, events induced by hydraulic fracturing experiments at the Fenton Hill, New Mexico, Hot Dry Rock (HDR) geothermal site, we find that the relationship between magnitude M and seismic moment (Mo) is log (Mo) = 17.27+0.77 M Moreover, the linear relationship between seismic moment and source radius (r) holds for the Fenton Hill microearthquakes. Analyses of the Fenton Hill data yield the following relationship. log (r) = 2.28+0.19 log (Mo)

  6. The bridge crane mechanism shaft reliability calculating in case of the fatigue fracture parameters correlation

    Directory of Open Access Journals (Sweden)

    Krutitskiy M.N.

    2016-03-01

    Full Text Available The method of statistical tests examines the impact of the correlation of the parameters of fatigue-such as the durability of the shaft mechanism of an overhead traveling crane for General use is under consideration in this article. It is be-lieved that the normal and shear stresses together affect the overall durability of the shaft. There may be a correlation between endurance limits and coefficients of block similarity of loading. To calculate resource used corrected linear theory of fatigue damage accumulation. Parameters on the reliability are computed after building the function, the reli-ability function directly or through private functions the reliability function for each type of stress.

  7. Vertebral fracture prevalence among Greek healthy middle-aged postmenopausal women: association with demographics, anthropometric parameters, and bone mineral density.

    Science.gov (United States)

    Lambrinoudaki, Irene; Flokatoula, Maria; Armeni, Eleni; Pliatsika, Paraskevi; Augoulea, Areti; Antoniou, Aris; Alexandrou, Andreas; Creatsa, Maria; Panoulis, Constantinos; Dendrinos, Spyridon; Papacharalambous, Xenofon

    2015-01-01

    The prevalence of skeletal fractures shows a marked geographic variability; however, data regarding the Greek population remain limited. To evaluate the frequency of asymptomatic vertebral fractures (VFs), and potential risk factors, in a large sample of Greek postmenopausal women. A cross-sectional study at the University Menopause Clinic. Four hundred fifty-four postmenopausal women aged 35 to 80 years, with an average menopausal age of 9.2±7.1 years. They included medical history, anthropometric and biochemical parameters, bone mineral density (BMD) at lumbar spine (LS) and femoral neck (FN), and LS lateral radiographs. Lumbar spine lateral radiographs were evaluated according to quantitative procedures, aiming to identify VFs. Anthropometric and biochemical parameters and values of BMD were compared according to the presence of VFs. A total of 37 (8.15%) women had at least one VF. Lumbar spine and FN-osteoporosis was identified in up to 23.1% and 40.9% subjects with prevalent VFs, respectively. The prevalence of VFs was largely associated with age, with women aged 60 years or more presenting an up to fourfold risk compared with younger women. Moreover, the presence of VFs was associated with higher menopausal age, advanced age at menarche, a history of early menopause, and prolonged lactation. Lower LS-BMD and, especially, FN-BMD were negatively associated with VF prevalence (prevalent VF vs. no VF: LS-BMD, 0.89±0.16 g/cm(2) vs. 0.98±0.16 g/cm(2), p=.010; FN-BMD, 0.72±0.10 g/cm(2) vs. 0.81±0.12 g/cm(2), p=.008). Asymptomatic VFs are common among Greek healthy middle-aged postmenopausal women. More than 50% subjects with prevalent VFs present with normal BMD or osteopenia. Age and bone density classification at the FN presented the strongest association with the prevalence of VFs. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Dependence of fracture toughness of molybdenum laser welds on processing parameters and in-situ oxygen gettering

    International Nuclear Information System (INIS)

    Pope, L.E.; Jellison, J.L.

    1980-01-01

    Fracture toughness properties have been determined for laser welds in different grades of molybdenum. The fracture toughness of welds in sintered molybdenum was consistently less than the fracture toughness of welds in vacuum arc remelted molybdenum. These differences cannot be attributed to oxygen content, since the oxygen level was nominally the same for all grades of molybdenum examined in this program. Alloy additions of titanium by means of physically deposited coatings significantly improved the fracture toughness of welds in sintered molybdenum, whereas titanium additions to welds in vacuum arc remelted molybdenum decreased the fracture toughness slightly. Pulsed laser welds exhibited fine columnar structures and, in the case of sintered molybdenum, superior fracture toughness when compared with continuous wave laser welds. 6 figures, 3 tables

  9. The Effect of Fracture Filler Composition on the Parameters of Shear Deformation Regime

    Science.gov (United States)

    Pavlov, D.; Ostapchuk, A.; Batuhtin, I.

    2015-12-01

    Geomechanical models of different slip mode nucleation and transformation can be developed basing on laboratory experiments, in which regularities of shear deformation of gouge-filled faults are studied. It's known that the spectrum of possible slip modes is defined by both macroscopic deformation characteristics of the fault and mesoscale structure of fault filler. Small variations of structural parameters of the filler may lead to a radical change of slip mode [1, 2]. This study presents results of laboratory experiments investigating regularities of shear deformation of discontinuities filled with multicomponent granular material. Qualitative correspondence between experimental results and natural phenomena is detected. The experiments were carried out in the classical "slider model" statement. A granite block slides under shear load on a granite substrate. The contact gap between rough surfaces was filled with a discrete material, which simulated the principal slip zone of a fault. The filler components were quartz sand, salt, glass beads, granite crumb, corundum, clay and pyrophyllite. An entire spectrum of possible slip modes was obtained - from stable slip to slow-slip events and to regular stick-slip with various coseismic displacements realized per one act of instability. Mixing several components in different proportions, it became possible to trace the gradual transition from stable slip to regular stick-slip, from slow-slip events to fast-slip events. Depending on specific filler component content, increasing the portion of one of the components may lead to both a linear and a non-linear change of slip event moment (a laboratory equivalent of the seismic moment). For different filler compositions durations of equal-moment events may differ by more than two orders of magnitude. The findings can be very useful for developing geomechnical models of nucleation and transformation of different slip modes observed at natural faults. The work was supported by

  10. 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.

  11. MICROTOUGH - calculation of characteristic upper shelf fracture toughness values from microstructural parameters for high strength structural steels with normalized or quenched and tempered microstructure

    International Nuclear Information System (INIS)

    Muenstermann, S.; Dahl, W.; Langenberg, P.; Deimel, P.; Sattler, E.

    2004-01-01

    In modern applications, high strength steels are often utilised to increase the load bearing capacity of components. For safe design it is also necessary that these steels have an adequate fracture toughness. The mechanical properties of high strength structural steels are a result of the production process. In consequence, they are strongly related to the microstructure. Therefore, the aim of the research work in the Microtough project is to develop and apply a new method of quantitative correlation between microstructural parameters and characteristic fracture toughness values. This correlation will on the one hand help for the design of new structural steels with high toughness. On the other hand, it shall allow to characterise the fracture toughness of steel without performing expensive fracture mechanics tests. The research work is carried out in the full temperature range from lower to upper shelf. As both RWTH Aachen University and MPA Uni Stuttgart concentrate on ductile fracture behaviour in their research work, the focus of the presentation lies in the upper shelf. (orig.)

  12. Comparison Thoracic Epidural and Intercostal Block to Improve Ventilation Parameters and Reduce Pain in Patients with Multiple Rib Fractures

    OpenAIRE

    Raheleh Aligholipour Maleki; Hamzeh Hosseinzadeh; Shahryar Hashemzadeh; Khosrov Hashemzadeh

    2011-01-01

    Introduction: Chest wall blunt trauma causes multiple rib fractures and will often be associated with significant pain and may compromise ventilator mechanics. Analgesia has great roll in rib fracture therapies, opioid are useful, but when used as sole agent may re-quire such high dose that they produce respiratory depression, especially in el-derly .the best analgesia for a severe chest wall injury is a continuous epidural infusion of local anesthetic. This provides complete analgesia allowi...

  13. Assessment of anthropometric parameters including area of the psoas, area of the back muscle, and psoas-vertebra distance as indices for prediction of vertebral fracture

    International Nuclear Information System (INIS)

    Suzuki, Tamotsu; Morita, Masahumi; Mabuchi, Kiyoshi

    2005-01-01

    We assessed some anthropometric parameters as indices for the prediction of vertebral compression fracture. We measured the area of the total cross section, area of the back muscle, area of the psoas, area of subcutaneous fat tissue, ratio of the right and left area of the psoas, psoas-vertebra distance, the mediolateral length of the back muscle, anteroposterior length of the back muscle, the mediolateral length of the psoas, and anteroposterior length of the psoas, on computed tomography images. Logistic regression analysis was performed in order to test the correlation between each anthropometric parameter and the incidence of fracture. The odds ratio corresponding to one standard deviation of each parameter was calculated. The ratio of center and anterior vertebral heights and the ratio of center and posterior vertebral heights were measured from the positioning image. The smaller value of these was defined as the vertebral height ratio value. Vertebral height ratio was used as the parameter directly related to vertebral fracture. The subjects for research were 25 women with vertebral compression fracture and 36 women without fracture. Vertebral height ratio had a significant correlation with area of the psoas (correlation coefficient, r=0.609 p<0.001), area of the back muscle (r=0.547 p<0.001), and the psoas-vertebra distance (r=-0.523 p<0.001) in the anthropometric parameters. The odds ratios of the area of the psoas (odds ratio, OR:0.18, 95% confidence interval, CI:0.43 to 0.08), area of the back muscle (OR:0.13, 95% CI:0.37 to 0.05), and the psoas-vertebra distance (OR:3.01, 95% CI:6.22 to 1.46) were high. The odds ratio of the mediolateral length of the psoas (OR:0.34, 95% CI:0.67 to 0.18), and the left-to-right area ratio of the psoas (OR:0.41, 95% CI:0.76 to 0.22) were rather high. However, the vertebral height ratio had no significant correlation with the left-to-right area ratio of the psoas. It was considered that area of the psoas, area of the back

  14. Fracture toughness correlations

    International Nuclear Information System (INIS)

    Wallin, Kim

    1986-09-01

    In this study existing fracture parameter correlations are reviewed. Their applicability and reliability are discussed in detail. A new K IC -CVN-correlation, based on a theoretical brittle fracture model, is presented

  15. Mid-thigh cortical bone structural parameters, muscle mass and strength, and association with lower limb fractures in older men and women (AGES-Reykjavik Study).

    Science.gov (United States)

    Johannesdottir, Fjola; Aspelund, Thor; Siggeirsdottir, Kristin; Jonsson, Brynjolfur Y; Mogensen, Brynjolfur; Sigurdsson, Sigurdur; Harris, Tamara B; Gudnason, Vilmundur G; Lang, Thomas F; Sigurdsson, Gunnar

    2012-05-01

    In a cross-sectional study we investigated the relationship between muscle and bone parameters in the mid-thigh in older people using data from a single axial computed tomographic section through the mid-thigh. Additionally, we studied the association of these variables with incident low-trauma lower limb fractures. A total of 3,762 older individuals (1,838 men and 1,924 women), aged 66-96 years, participants in the AGES-Reykjavik study, were studied. The total cross-sectional muscular area and knee extensor strength declined with age similarly in both sexes. Muscle parameters correlated most strongly with cortical area and total shaft area (adjusted for age, height, and weight) but explained lower limb fractures. Small muscular area, low knee extensor strength, large MA, low cortical thickness, and high BR were significantly associated with fractures in both sexes. Our results show that bone and muscle loss proceed at different rates and with different gender patterns.

  16. Examination of parameters affecting overload fracture behavior of flaw-tip hydrides in Zr-2.5Nb pressure tubes in Candu reactors

    International Nuclear Information System (INIS)

    Cui, J.; Shek, G.K.; Wang, Z.R.

    2007-01-01

    Service-induced flaws in Zr-2.5Nb alloy pressure tubes in Candu (Canada Deuterium Uranium Reactors) nuclear reactors are susceptible to a crack initiation and growth mechanism known as Delayed Hydride Cracking (DHC), which is a repetitive process that involves hydrogen diffusion, hydride precipitation, growth and fracture of a hydride region at the flaw-tip under a constant load. Crack initiation may also occur under another loading condition when the hydride region is subjected to an overload. An overload occurs when the hydride region at the flaw tip is loaded to a stress higher than that at which this region is formed such as when the reactor experiences a transient pressure higher than the normal operating pressure where the hydride region is formed. Flaw disposition requires justification that the hydride region overload will not fracture the hydride region, and initiate DHC. In this work, monotonically increasing load experiments were performed on unirradiated Zr-2.5Nb pressure tube specimens containing simulated debris frets (V-notch) and bearing pad frets (BPF, U-shape notch) to examine overload fracture behavior of flaw-tip hydrides formed under hydride ratcheting conditions. Hydride cracking in the overload tests was detected by the acoustic emission technique and confirmed by post-test metallurgical examination. Test results indicate that the resistance to overload fracture is affected by a number of parameters including hydride formation stress, flaw shape (V-notch vs. BPF) and flaw radius (0.015 mm vs. 0.1 mm). The notch-tip hydride morphologies were examined by optical microscopy and scanning electron microscopy (SEM) which show that they are affected by the hydride formation conditions, resulting in different overload fracture resistance. Finite element stress analyses were also performed to obtain flaw-tip stress distributions for interpretation of the test results. (authors)

  17. Comparison thoracic epidural and intercostal block to improve ventilation parameters and reduce pain in patients with multiple rib fractures.

    Science.gov (United States)

    Hashemzadeh, Shahryar; Hashemzadeh, Khosrov; Hosseinzadeh, Hamzeh; Aligholipour Maleki, Raheleh; Golzari, Samad E J; Golzari, Samad

    2011-01-01

    Chest wall blunt trauma causes multiple rib fractures and will often be associated with significant pain and may compromise ventilator mechanics. Analgesia has great roll in rib fracture therapies, opioid are useful, but when used as sole agent may require such high dose that they produce respiratory depression, especially in elderly .the best analgesia for a severe chest wall injury is a continuous epidural infusion of local anesthetic. This provides complete analgesia allowing inspiration and coughing without of the risk of respiratory depression. sixty adult patients who with multiple rib fractures were enrolled in this study. They were divided into Group A or thoracic epidural with bupivacaine 0.125 % +1mg/5ml morphine and group B or intercostal block with 0.25% bupivacaine. The patients were assessed through ICU and hospital stay length, ventilation function tests. Pain score among the patients was measured with verbal rating scale, before and after administration of the analgesia. We found a significant improvement in ventilatory function tests during the 1st, 2nd, and 3rd days after epidural analgesia compared with the intercostal block (P pain at rest and pain caused by coughing and deep breathing in group A compared group B... ICU and hospital stay markedly reduced in Group A. thoracic epidural analgesia is superior to intercostals block regarding pain relief of rib fractures. Patients who received epidural analgesia had significantly lower pain scores at all studied times.

  18. Wedge splitting test method: quantification of influence of glued marble plates by two-parameter fracture mechanics

    Czech Academy of Sciences Publication Activity Database

    Seitl, Stanislav; Nieto Garcia, B.; Merta, I.

    2014-01-01

    Roč. 30, OCT (2014), s. 174-181 ISSN 1971-8993 R&D Projects: GA MŠk(CZ) 7AMB14AT012 Institutional support: RVO:68081723 Keywords : Wedge splitting test * T-stress * K-calibration curves * Stress intensity factor * Concrete fracture test Subject RIV: JL - Materials Fatigue, Friction Mechanics

  19. Comparison Thoracic Epidural and Intercostal Block to Improve Ventilation Parameters and Reduce Pain in Patients with Multiple Rib Fractures

    Directory of Open Access Journals (Sweden)

    Raheleh Aligholipour Maleki

    2011-08-01

    Full Text Available Introduction: Chest wall blunt trauma causes multiple rib fractures and will often be associated with significant pain and may compromise ventilator mechanics. Analgesia has great roll in rib fracture therapies, opioid are useful, but when used as sole agent may re-quire such high dose that they produce respiratory depression, especially in el-derly .the best analgesia for a severe chest wall injury is a continuous epidural infusion of local anesthetic. This provides complete analgesia allowing inspiration and coughing without of the risk of respiratory depression. Methods: sixty adult patients who with multiple rib fractures were enrolled in this study. They were divided into Group A or thoracic epidural with bupivacaine 0.125 % +1mg/5ml morphine and group B or inter-costal block with %0.25 bupivacaine. The patients were assessed through ICU and hos-pital stay length, ventilation function tests. Pain score among the patients was meas-ured with verbal rating scale, before and after administration of the analgesia. Results: We found a significant improvement in ventilatory function tests during the 1st, 2nd, and 3rd days after epidural analgesia compared with the intercostal block (P < 0.004. Changes in the visual Analogue Scale were associated with marked improvement re-garding pain at rest and pain caused by coughing and deep breathing in group A com-pared group B... ICU and hospital stay markedly reduced in Group A. Conclusion: tho-racic epidural analgesia is superior to intercostals block regarding pain relief of rib frac-tures. Patients who received epidural analgesia had significantly lower pain scores at all studied times.

  20. Multi-parameter crack tip stress state description for estimation of fracture process zone extent in silicate composite WST specimens

    Czech Academy of Sciences Publication Activity Database

    Veselý, V.; Sobek, J.; Šestáková, L.; Frantík, P.; Seitl, Stanislav

    2013-01-01

    Roč. 7, č. 25 (2013), s. 69-78 ISSN 1971-8993 R&D Projects: GA ČR(CZ) GAP104/11/0833; GA ČR(CZ) GAP105/11/1551 Institutional support: RVO:68081723 Keywords : Near-crack tip fields * Williams series * higher-order terms * stress field approximation * wedge splitting test * fracture process zone Subject RIV: JL - Materials Fatigue, Friction Mechanics

  1. 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.

  2. A novel source convergence acceleration scheme for Monte Carlo criticality calculations, part I: Theory

    International Nuclear Information System (INIS)

    Griesheimer, D. P.; Toth, B. E.

    2007-01-01

    A novel technique for accelerating the convergence rate of the iterative power method for solving eigenvalue problems is presented. Smoothed Residual Acceleration (SRA) is based on a modification to the well known fixed-parameter extrapolation method for power iterations. In SRA the residual vector is passed through a low-pass filter before the extrapolation step. Filtering limits the extrapolation to the lower order Eigenmodes, improving the stability of the method and allowing the use of larger extrapolation parameters. In simple tests SRA demonstrates superior convergence acceleration when compared with an optimal fixed-parameter extrapolation scheme. The primary advantage of SRA is that it can be easily applied to Monte Carlo criticality calculations in order to reduce the number of discard cycles required before a stationary fission source distribution is reached. A simple algorithm for applying SRA to Monte Carlo criticality problems is described. (authors)

  3. Evaluation of J and CTOD (Crack Tip Opening Displacement) fracture parameters for pipeline steels using Single Edge Notch Tension SE(T) specimens

    Energy Technology Data Exchange (ETDEWEB)

    Paredes Tobar, Lenin Marcelo; Ruggieri, Claudio [Universidade de Sao Paulo (USP), SP (Brazil). Escola Politecnica. Dept. de Engenharia Naval e Oceanica

    2009-12-19

    This work presents an evaluation procedure to determine the elastic-plastic J-integral and CTOD for pin-loaded and clamped single edge notch tension (SE(T)) specimens based upon the eta-method. The primary objective is to derive estimation equations applicable to determine J and CTOD fracture parameters for a wide range of a/W-ratios and material flow properties. Very detailed non-linear finite element analyses for plane-strain and full-thickness, 3-D models provide the evolution of load with increased crack mouth opening displacement which is required for the estimation procedure. The present analyses, when taken together with previous studies provide a fairly extensive body of results which serve to determine parameters J and CTOD for different materials using tension specimens with varying geometries. (author)

  4. Four-channel multidetector-row computed tomography in the evaluation of facial fractures - optimized parameters for acquisition and multiplanar reformation

    International Nuclear Information System (INIS)

    Omid, P. M.

    2002-08-01

    The first part of this thesis is designed to give the reader a comprehensive survey on the complex basic principles of computed tomography (CT), from the early beginning to the recent development of multidetector-row CT (MD-CT). Attention is focused on imaging of trauma in general and on imaging of facial fractures in particular. The second part of this thesis describes a clinical study performed to optimize acquisition protocols and multiplanar reformation (MPR) algorithms for the evaluation of facial fractures using MD-CT, which has not been yet described in literature. For this study, a cadaver head with artificial blunt facial trauma was examined using a 4-channel MD-CT scanner. The influence of acquisition parameters (collimation: 2x0.5 mm/4x1 mm/4x2.5 mm; tube current: 120 mAs/90 mAs/60 mAs), image reconstruction algorithms (standard vs. ultra-high resolution (UHR) modes; reconstructed slice thicknesses: 0.5 mm/1 mm/3 mm; increment: 0.3 mm/0.6 mm/1.5 mm), and reformation algorithms (slice thicknesses: 0.5 mm/1 mm/3 mm; overlap: 0.5 mm/1 mm/3 mm) on detectability of facial fractures in MPRs with MD-CT was analyzed. Effects of algorithms and parameters on image noise, artifacts and delineation of soft tissues were evaluated. The results of this study reliably demonstrate that fracture detection was significantly higher with thin MPRs (0.5/0.5 mm, 1/0.5 mm, 1/1 mm) (p = 0 .014) acquired with 2x0.5 mm collimation (p = 0 .046), in UHR mode (p .0005) with 120 mAs (p = 0 .025). Inter-observer variability showed very good agreement (κ > = 0 .942). Non-UHR mode, lower mAs and thick MPRs (3/0.5 mm, 3/1 mm, 3/0.5 mm) showed significantly decreased detectability. (author)

  5. Effect of Process Parameters on Fatigue and Fracture Behavior of Al-Cu-Mg Alloy after Creep Aging

    Directory of Open Access Journals (Sweden)

    Lihua Zhan

    2018-04-01

    Full Text Available A set of creep aging tests at different aging temperatures and stress levels were carried out for Al-Cu-Mg alloy, and the effects of creep aging on strength and fatigue fracture behavior were studied through tensile tests and fatigue crack propagation tests. The microstructures were further analyzed by using scanning electron microscopy (SEM and transmission electron microscopy (TEM. The results show that temperature and stress can obviously affect the creep behavior, mechanical properties, and fatigue life of Al-Cu-Mg alloy. As the aging temperature increases, the fatigue life of alloy first increases, and then decreases. The microstructure also displays a transition from the Guinier-Preston-Bagaryatsky (GPB zones to the precipitation of S phase in the grain interior. However, the precipitation phases grow up and become coarse at excessive temperatures. Increasing stress can narrow the precipitation-free zone (PFZ at the grain boundary and improve the fatigue life, but overhigh stress can produce the opposite result. In summary, the fatigue life of Al-Cu-Mg alloy can be improved by fine-dispersive precipitation phases and a narrow PFZ in a suitable creep aging process.

  6. Fracture mechanics safety approaches

    International Nuclear Information System (INIS)

    Roos, E.; Schuler, X.; Eisele, U.

    2004-01-01

    Component integrity assessments require the knowledge of reliable fracture toughness parameters characterising the initiation of the failure process in the whole relevant temperature range. From a large number of fracture mechanics tests a statistically based procedure was derived allowing to quantify the initiation of fracture toughness as a function of temperature as a closed function as well as the temperature dependence of the cleavage instability parameters. Alternatively to the direct experimental determination one also can use a correlation between fracture toughness and notch impact energy. (orig.)

  7. Applicability of geostatistical procedures for the evaluation of hydrogeological parameters of a fractured aquifer in the Ronneburg mine district

    International Nuclear Information System (INIS)

    Grasshoff, C.; Schetelig, K.; Tomschi, H.

    1998-01-01

    The following paper demonstrates, how a geostatistical approach can help interpolating hydrogeological parameters over a certain area. The basic elements developed by G. Matheron in the sixties are represented as the preconditions and assumptions, which provide the best results of the estimation. The variogram as the most important tool in geostatistics offers the opportunity to describe the correlating behaviour of a regionalized variable. Some kriging procedures are briefly introduced, which provide under varying circumstances estimating of non-measured values with the theoretical variogram-model. In the Ronneburg mine district 108 screened drill-holes could provide coefficients of hydraulic conductivity. These were interpolated with ordinary kriging over the whole investigation area. An error calculation was performed, which could prove the accuracy of the estimation. Short prospects point out some difficulties handling with geostatistic procedures and make suggestions for further investigations. (orig.) [de

  8. Estimation of the crack growth mechanism in the coking process. ; Behavior of fracture mechanics parameter. Cokes sonai kiretsu shinten ni kansuru ichikosatsu. ; Hakai rikigaku parameter no kyodo ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Yoshino, H; Sato, H; Nogami, H; Miura, T [Tohoku University, Sendai (Japan). Faculty of Engineering

    1991-07-10

    Cracks generated in coke layers during a coking furnace operation are an important factor not only to decide quality of the product, but also govern the energy consumption affecting the heat transfer and material transfer. This paper describes estimations of thermal stress and observations to fracture mechanics parameters, applying the incremental theory to surface cracks seen in the initial stage of carbonization. As a result of calculations using the crack tip opening displacement (CTOD) as a parameter to evaluate displacement in the vicinity of crack tips, the values increased with the increasing heating rate, and agreed qualitatively with the trend found in the experiments. The CTOD relates closely to the temperature dependence of the contraction coefficient, and varies largely at the transition point from the first maximum point to the second maximum point, from which the surface cracks are predicted to have been generated in this temperature region. Also, an estimation was made on the stress expansion coefficient from the stress distribution, and a result that can explain the experimental resultswas obtained. 10 refs., 11 figs.

  9. A proposal for evaluation method of crack growth due to cyclic overload for piping materials based on an elastic-plastic fracture mechanics parameter

    International Nuclear Information System (INIS)

    Yamaguchi, Yoshihito; Katsuyama, Jinya; Onizawa, Kunio; Li, Yinsheng; Sugino, Hideharu

    2011-01-01

    The magnitude of Niigata-ken Chuetsu-Oki earthquake in 2007 was beyond the assumed one provided in seismic design. Therefore it becomes an important issue to evaluate the crack growth behaviors due to the cyclic overload like large earthquake. Fatigue crack growth is usually evaluated by Paris's law using the range of stress intensity factor (ΔK). However, ΔK is inappropriate in a loading condition beyond small scale yielding. In this study, the crack growth behaviors for piping materials were investigated based on an elastic-plastic fracture mechanics parameter, J-integral. It was indicated that the crack growth due to the cyclic overload beyond small scale yielding could be the sum of fatigue and ductile crack growth. The retardation effect of excessive loading on the crack growth was observed after the loading. The modified Wheeler model using J-integral has been proposed for the prediction of retardation effect. Finally, an evaluation method for crack growth behaviors due to the cyclic overload is suggested. (author)

  10. Can Clinical and Surgical Parameters Be Combined to Predict How Long It Will Take a Tibia Fracture to Heal? A Prospective Multicentre Observational Study: The FRACTING Study

    Directory of Open Access Journals (Sweden)

    Leo Massari

    2018-01-01

    Full Text Available Background. Healing of tibia fractures occurs over a wide time range of months, with a number of risk factors contributing to prolonged healing. In this prospective, multicentre, observational study, we investigated the capability of FRACTING (tibia FRACTure prediction healING days score, calculated soon after tibia fracture treatment, to predict healing time. Methods. The study included 363 patients. Information on patient health, fracture morphology, and surgical treatment adopted were combined to calculate the FRACTING score. Fractures were considered healed when the patient was able to fully weight-bear without pain. Results. 319 fractures (88% healed within 12 months from treatment. Forty-four fractures healed after 12 months or underwent a second surgery. FRACTING score positively correlated with days to healing: r=0.63 (p<0.0001. Average score value was 7.3 ± 2.5; ROC analysis showed strong reliability of the score in separating patients healing before versus after 6 months: AUC = 0.823. Conclusions. This study shows that the FRACTING score can be employed both to predict months needed for fracture healing and to identify immediately after treatment patients at risk of prolonged healing. In patients with high score values, new pharmacological and nonpharmacological treatments to enhance osteogenesis could be tested selectively, which may finally result in reduced disability time and health cost savings.

  11. Elevated temperature fracture mechanics

    International Nuclear Information System (INIS)

    Tomkins, B.

    1979-01-01

    The application of fracture mechanics concepts to cracks at elevated temperatures is examined. Particular consideration is given to the characterisation of crack tip stress-strain fields and parameters controlling crack extension under static and cyclic loads. (author)

  12. Radiographic anatomy of the proximal femur: femoral neck fracture vs. transtrochanteric fracture

    Directory of Open Access Journals (Sweden)

    Ana Lecia Carneiro Leão de Araújo Lima

    Full Text Available ABSTRACT OBJECTIVE: To evaluate the correlation between radiographic parameters of the proximal femur with femoral neck fractures or transtrochanteric fractures. METHODS: Cervicodiaphyseal angle (CDA, femoral neck width (FNW, hip axis length (HAL, and acetabular tear drop distance (ATD were analyzed in 30 pelvis anteroposterior view X-rays of patients with femoral neck fractures (n = 15 and transtrochanteric fractures (n = 15. The analysis was performed by comparing the results of the X-rays with femoral neck fractures and with transtrochanteric fractures. RESULTS: No statistically significant differences between samples were observed. CONCLUSION: There was no correlation between radiographic parameters evaluated and specific occurrence of femoral neck fractures or transtrochanteric fractures.

  13. Parameters controlling fracturing distribution: example of an Upper Jurassic marly-calcareous formation (eastern Paris Basin); Parametres controlant la distribution de la fracturation: exemple dans une serie marno-calcaire du Jurassique superieur (Est du bassin de Paris)

    Energy Technology Data Exchange (ETDEWEB)

    Andre, G.; Rebours, H.; Wileveau, Y. [Agence Nationale pour la Gestion des Dechets Radioactifs (ANDRA), Laboratoire de recherche souterrain de Meuse/Haute-Marne, 55 - Bure (France); Proudhon, B. [GEO.TER, 34 - Clapiers (France)

    2006-10-15

    Study of fractures along a 490-m vertical section of marl/limestone alternations in the Upper Jurassic (Meuse/Haute-Marne underground research laboratory-eastern Paris Basin) reveals their organization and the different states of palaeo-stress. Type and extension of tectonic structures seem to be controlled principally by lithology and secondary by depth. Also, it appears deviations of Alpine palaeo-stresses between Kimmeridgian and Oxfordian formations. These deviations are related to the presence of marl/limestone contacts. The vertical evolution of current horizontal maximum stress shows a similar behaviour, with deviations at the walls of Callovo-Oxfordian argilites. These results allow us to point out and to discuss the impact of lithology, rheology and depth on fracturing occurrence and distribution. Furthermore, this study suggests the role of Callovo-Oxfordian as a barrier for fracture development between the limestones of Dogger and Oxfordian formations. (authors)

  14. Hip Fracture

    Science.gov (United States)

    ... hip fractures in people of all ages. In older adults, a hip fracture is most often a result of a fall from a standing height. In people with very weak bones, a hip fracture can occur simply by standing on the leg and twisting. Risk factors The rate of hip fractures increases substantially with ...

  15. TIBIAL SHAFT FRACTURES.

    Science.gov (United States)

    Kojima, Kodi Edson; Ferreira, Ramon Venzon

    2011-01-01

    The long-bone fractures occur most frequently in the tibial shaft. Adequate treatment of such fractures avoids consolidation failure, skewed consolidation and reoperation. To classify these fractures, the AO/OTA classification method is still used, but it is worthwhile getting to know the Ellis classification method, which also includes assessment of soft-tissue injuries. There is often an association with compartmental syndrome, and early diagnosis can be achieved through evaluating clinical parameters and constant clinical monitoring. Once the diagnosis has been made, fasciotomy should be performed. It is always difficult to assess consolidation, but the RUST method may help in this. Radiography is assessed in two projections, and points are scored for the presence of the fracture line and a visible bone callus. Today, the dogma of six hours for cleaning the exposed fracture is under discussion. It is considered that an early start to intravenous antibiotic therapy and the lesion severity are very important. The question of early or late closure of the lesion in an exposed fracture has gone through several phases: sometimes early closure has been indicated and sometimes late closure. Currently, whenever possible, early closure of the lesion is recommended, since this diminishes the risk of infection. Milling of the canal when the intramedullary nail is introduced is still a controversial subject. Despite strong personal positions in favor of milling, studies have shown that there may be some advantage in relation to closed fractures, but not in exposed fractures.

  16. Hydrologic behavior of fracture networks

    International Nuclear Information System (INIS)

    Long, J.C.S.; Endo, H.K.; Karasaki, K.; Pyrak, L.; MacLean, P.; Witherspoon, P.A.

    1985-01-01

    This paper reviews recent research on the nature of flow and transport in discontinuous fracture networks. The hydrologic behavior of these networks has been examined using two- and three-dimensional numerical models. The numerical models represent random realizations of fracture networks based on statistical field measurements of fracture geometry and equivalent hydraulic aperture. The authors have compared the flux and mechanical transported behavior of these networks to the behavior of equivalent continua. In this way they were able to determine whether a given fracture network could be modeled as an equivalent porous media in both flux and advective transport studies. They have examined departures from porous media behavior both as a function of interconnectivity and heterogeneity. Parameter studies have revealed behavior patterns such as: given a fracture frequency that can be measured in the field, porous media like behavior and the magnitude of permeability are both enhanced if the fractures are longer and the standard deviation of fracture permeabilities is smaller. The behavior of well tests in fractured networks has been modeled and compared to a new analytical well test solution which accounts for the early time dominance of the fractures intersecting the well. Finally, a three-dimensional fracture flow model has been constructed which assumes fractures are randomly located discs. This model has been constructed which assumes fractures are randomly located discs. This model uses a semi-analytical solution for flow such that it is relatively easy to use the model as a tool for stochastic analysis. 13 references, 12 figures

  17. Rib Fractures

    Science.gov (United States)

    ... Video) Achilles Tendon Tear Additional Content Medical News Rib Fractures By Thomas G. Weiser, MD, MPH, Associate Professor, ... Tamponade Hemothorax Injury to the Aorta Pulmonary Contusion Rib Fractures Tension Pneumothorax Traumatic Pneumothorax (See also Introduction to ...

  18. Root fractures

    DEFF Research Database (Denmark)

    Andreasen, Jens Ove; Christensen, Søren Steno Ahrensburg; Tsilingaridis, Georgios

    2012-01-01

    The purpose of this study was to analyze tooth loss after root fractures and to assess the influence of the type of healing and the location of the root fracture. Furthermore, the actual cause of tooth loss was analyzed....

  19. Hydraulic fracture propagation modeling and data-based fracture identification

    Science.gov (United States)

    Zhou, Jing

    parameters used in the reservoir flow simulator have large uncertainty. Those biased and uncertain parameters will result in misleading oil and gas recovery predictions. The Ensemble Kalman Filter is used to estimate and update both the state variables (pressure and saturations) and uncertain reservoir parameters (permeability). In order to directly incorporate spatial information such as fracture location and formation heterogeneity into the algorithm, a new covariance matrix method is proposed. This new method has been applied to a simplified single-phase reservoir and a complex black oil reservoir with complex structures to prove its capability in calibrating the reservoir parameters.

  20. Stress Fractures

    Science.gov (United States)

    Stress fractures Overview Stress fractures are tiny cracks in a bone. They're caused by repetitive force, often from overuse — such as repeatedly jumping up and down or running long distances. Stress fractures can also arise from normal use of ...

  1. On effect of some thermodeformation parameters of welding cycle on tendency of pearlitic heat-resisting steels to fracture in reheating

    International Nuclear Information System (INIS)

    Prokhorov, N.N.; Bardokin, E.V.

    1979-01-01

    Studied is the inclination of the 12Kh1MF, 15Kh3M1F and N18K9M5T steels subject to thermodeformation cycle imitating a welding one, to fracture in reheating. A hot-rolled metal then subject to the same thermal treatment was used. The imitation of thermodeformation cycle of the welding permitted to vary maximum heating temperatures, the period during which the metal is kept at temperatures higher than 1100 deg C, and the cooling rate of ajacent zone metal. It is shown that the curve of the dependence of deformation ability and the tendency to fracture at the reheating of adjacent zone metal on the rate of its cooling at welding is U-shaped. Deformation ability has its maximum value at the cooling rate of 30 deg c/s in the range 1300 to 1000 deg C

  2. Analysis of Dynamic Fracture Parameters in Functionally Graded Material Plates with Cracks by Graded Finite Element Method and Virtual Crack Closure Technique

    Directory of Open Access Journals (Sweden)

    Li Ming Zhou

    2016-01-01

    Full Text Available Based on the finite element software ABAQUS and graded element method, we developed a dummy node fracture element, wrote the user subroutines UMAT and UEL, and solved the energy release rate component of functionally graded material (FGM plates with cracks. An interface element tailored for the virtual crack closure technique (VCCT was applied. Fixed cracks and moving cracks under dynamic loads were simulated. The results were compared to other VCCT-based analyses. With the implementation of a crack speed function within the element, it can be easily expanded to the cases of varying crack velocities, without convergence difficulty for all cases. Neither singular element nor collapsed element was required. Therefore, due to its simplicity, the VCCT interface element is a potential tool for engineers to conduct dynamic fracture analysis in conjunction with commercial finite element analysis codes.

  3. Tuning Fractures With Dynamic Data

    Science.gov (United States)

    Yao, Mengbi; Chang, Haibin; Li, Xiang; Zhang, Dongxiao

    2018-02-01

    Flow in fractured porous media is crucial for production of oil/gas reservoirs and exploitation of geothermal energy. Flow behaviors in such media are mainly dictated by the distribution of fractures. Measuring and inferring the distribution of fractures is subject to large uncertainty, which, in turn, leads to great uncertainty in the prediction of flow behaviors. Inverse modeling with dynamic data may assist to constrain fracture distributions, thus reducing the uncertainty of flow prediction. However, inverse modeling for flow in fractured reservoirs is challenging, owing to the discrete and non-Gaussian distribution of fractures, as well as strong nonlinearity in the relationship between flow responses and model parameters. In this work, building upon a series of recent advances, an inverse modeling approach is proposed to efficiently update the flow model to match the dynamic data while retaining geological realism in the distribution of fractures. In the approach, the Hough-transform method is employed to parameterize non-Gaussian fracture fields with continuous parameter fields, thus rendering desirable properties required by many inverse modeling methods. In addition, a recently developed forward simulation method, the embedded discrete fracture method (EDFM), is utilized to model the fractures. The EDFM maintains computational efficiency while preserving the ability to capture the geometrical details of fractures because the matrix is discretized as structured grid, while the fractures being handled as planes are inserted into the matrix grids. The combination of Hough representation of fractures with the EDFM makes it possible to tune the fractures (through updating their existence, location, orientation, length, and other properties) without requiring either unstructured grids or regridding during updating. Such a treatment is amenable to numerous inverse modeling approaches, such as the iterative inverse modeling method employed in this study, which is

  4. Flow characteristics through a single fracture of artificial fracture system

    International Nuclear Information System (INIS)

    Park, Byoung Yoon; Bae, Dae Seok; Kim, Chun Soo; Kim, Kyung Su; Koh, Young Kwon; Jeon, Seok Won

    2001-04-01

    Fracture flow in rock masses is one of the most important issues in petroleum engineering, geology, and hydrogeology. Especially, in case of the HLW disposal, groundwater flow in fractures is an important factor in the performance assessment of the repository because the radionuclides move along the flowing groundwater through fractures. Recently, the characterization of fractures and the modeling of fluid flow in fractures are studied by a great number of researchers. Among those studies, the hydraulic behavior in a single fracture is one of the basic issues for understanding of fracture flow in rockmass. In this study, a fluid flow test in the single fracture made of transparent epoxy replica was carried out to obtain the practical exponent values proposed from the Cubic law and to estimate the flow rates through a single fracture. Not only the relationship between flow rates and the geometry of fracture was studied, but also the various statistical parameters of fracture geometry were compared to the effective transmissivity data obtained from computer simulation.

  5. Acetabular Fracture

    Directory of Open Access Journals (Sweden)

    Chad Correa

    2017-09-01

    Full Text Available History of present illness: A 77-year-old female presented to her primary care physician (PCP with right hip pain after a mechanical fall. She did not lose consciousness or have any other traumatic injuries. She was unable to ambulate post-fall, so X-rays were ordered by her PCP. Her X-rays were concerning for a right acetabular fracture (see purple arrows, so the patient was referred to the emergency department where a computed tomography (CT scan was ordered. Significant findings: The non-contrast CT images show a minimally displaced comminuted fracture of the right acetabulum involving the acetabular roof, medial and anterior walls (red arrows, with associated obturator muscle hematoma (blue oval. Discussion: Acetabular fractures are quite rare. There are 37 pelvic fractures per 100,000 people in the United States annually, and only 10% of these involve the acetabulum. They occur more frequently in the elderly totaling an estimated 4,000 per year. High-energy trauma is the primary cause of acetabular fractures in younger individuals and these fractures are commonly associated with other fractures and pelvic ring disruptions. Fractures secondary to moderate or minimal trauma are increasingly of concern in patients of advanced age.1 Classification of acetabular fractures can be challenging. However, the approach can be simplified by remembering the three basic types of acetabular fractures (column, transverse, and wall and their corresponding radiologic views. First, column fractures should be evaluated with coronally oriented CT images. This type of fracture demonstrates a coronal fracture line running caudad to craniad, essentially breaking the acetabulum into two halves: a front half and a back half. Secondly, transverse fractures should be evaluated by sagittally oriented CT images. By definition, a transverse fracture separates the acetabulum into superior and inferior halves with the fracture line extending from anterior to posterior

  6. Factors affecting neutron measurements and calculations. Part C. Trace element concentrations in granite and their impact on thermal neutron activation

    International Nuclear Information System (INIS)

    Ruehm, Werner; Huber, Thomas; Nolte, Eckehart; Kato, Kazuo; Imanaka, Tetsuji; Egbert, Stephen D.

    2005-01-01

    Trace elements such as Li, B, Sm, and Gd can, despite their low elemental concentration in mineral materials, influence thermal neutron activation in Hiroshima and Nagasaki samples, due to their high thermal neutron absorption cross sections. This was demonstrated for a granite core, where the addition of those trace elements to the elemental composition of granite reduces the production of 152 Eu by some 25% at a depth of 25 cm from the surface. If typical concentrations of those trace elements are added to DS02 reference soil, however, the production of 152 Eu one meter above ground is not changed significantly, because of the high water content of the soil. This indicates that DS02 soil represents a reasonable reference material for the air-over-ground transport calculations. It must be kept in mind, however, that the local environment of any sample investigated for thermal neutron activation might be characterized by other elemental compositions. In particular, trace element and hydrogen concentrations could be considerably different from those used for DS02 reference soil. As an example it was demonstrated that in a granite gravestone thermal neutron activation of 36 Cl close to the surface might be, in the worst case, reduced by some 30%, due to increased local granite concentration in this type of environment. Beside other parameters such as, for example, individual sample geometry, the variability of trace elements in soil might be one reason for the variability that is observed in the individual thermal neutron activation measurements (Gold 1995). It is necessary, therefore, to carefully model the exposure geometry of the exposed material, its chemical composition, and the surrounding interface materials in order to obtain the best possible agreement in comparisons between calculated and measured data for thermal neutrons. (author)

  7. Mandible Fractures.

    Science.gov (United States)

    Pickrell, Brent B; Serebrakian, Arman T; Maricevich, Renata S

    2017-05-01

    Mandible fractures account for a significant portion of maxillofacial injuries and the evaluation, diagnosis, and management of these fractures remain challenging despite improved imaging technology and fixation techniques. Understanding appropriate surgical management can prevent complications such as malocclusion, pain, and revision procedures. Depending on the type and location of the fractures, various open and closed surgical reduction techniques can be utilized. In this article, the authors review the diagnostic evaluation, treatment options, and common complications of mandible fractures. Special considerations are described for pediatric and atrophic mandibles.

  8. Fractal description of fractures

    International Nuclear Information System (INIS)

    Lung, C.W.

    1991-06-01

    Recent studies on the fractal description of fractures are reviewed. Some problems on this subject are discussed. It seems hopeful to use the fractal dimension as a parameter for quantitative fractography and to apply fractal structures to the development of high toughness materials. (author). 28 refs, 7 figs

  9. [Periprosthetic knee fractures].

    Science.gov (United States)

    Mittlmeier, T; Beck, M; Bosch, U; Wichelhaus, A

    2016-01-01

    The cumulative incidence of periprosthetic fractures around the knee is increasing further because of an extended indication for knee replacement, previous revision arthroplasty, rising life expectancy and comorbidities. The relevance of local parameters such as malalignment, osseous defects, neighbouring implants, aseptic loosening and low-grade infections may sometimes be hidden behind the manifestation of a traumatic fracture. A differentiated diagnostic approach before the treatment of a periprosthetic fracture is of paramount importance, while the physician in-charge should also have particular expertise in fracture treatment and in advanced techniques of revision endoprosthetics. The following work gives an overview of this topic. Valid classifications are available for categorising periprosthetic fractures of the femur, the tibia and the patella respectively, which are helpful for the selection of treatment. With the wide-ranging modern treatment portfolio bearing in mind the substantial rate of complications and the heterogeneous functional outcome, the adequate analysis of fracture aetiology and the corresponding transformation into an individualised treatment concept offer the chance of an acceptable functional restoration of the patient at early full weight-bearing and prolonged implant survival. The management of complications is crucial to the final outcome.

  10. High prevalence of simultaneous rib and vertebral fractures in patients with hip fracture.

    Science.gov (United States)

    Lee, Bong-Gun; Sung, Yoon-Kyoung; Kim, Dam; Choi, Yun Young; Kim, Hunchul; Kim, Yeesuk

    2017-02-01

    The purpose was to evaluate the prevalence and location of simultaneous fracture using bone scans in patients with hip fracture and to determine the risk factors associated with simultaneous fracture. One hundred eighty two patients with hip fracture were reviewed for this study. Clinical parameters and bone mineral density (BMD) of the lumbar vertebra and femoral neck were investigated. To identify acute simultaneous fracture, a bone scan was performed at 15.4±4.1days after hip fracture. The prevalence and location of simultaneous fracture were evaluated, and multivariate logistic regression analysis was performed to determine the risk factors. Simultaneous fracture was observed in 102 of 182 patients, a prevalence of 56.0%. Rib fracture was the most common type of simultaneous fracture followed by rib with vertebral fracture. The BMD of the lumbar vertebra was significantly lower in patients with simultaneous fracture (p=0.044) and was identified as an independent risk factor (odds ratio: OR 0.05, 95% confidence interval: CI 0.01-0.57). The prevalence of simultaneous fracture was relatively high among patients with hip fracture, and BMD was significantly lower in patients with simultaneous fracture than in patients without it. Surgeons should be aware of the possibility of simultaneous fracture in patients with hip fracture. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Dimensional threshold for fracture linkage and hooking

    Science.gov (United States)

    Lamarche, Juliette; Chabani, Arezki; Gauthier, Bertrand D. M.

    2018-03-01

    Fracture connectivity in rocks depends on spatial properties of the pattern including length, abundance and orientation. When fractures form a single-strike set, they hardly cross-cut each other and the connectivity is limited. Linkage probability increases with increasing fracture abundance and length as small fractures connect to each other to form longer ones. A process for parallel fracture linkage is the "hooking", where two converging fracture tips mutually deviate and then converge to connect due to the interaction of their crack-tip stresses. Quantifying the processes and conditions for fracture linkage in single-strike fracture sets is crucial to better predicting fluid flow in Naturally Fractured Reservoirs. For 1734 fractures in Permian shales of the Lodève Basin, SE France, we measured geometrical parameters in 2D, characterizing three stages of the hooking process: underlapping, overlapping and linkage. We deciphered the threshold values, shape ratios and limiting conditions to switch from one stage to another one. The hook set up depends on the spacing (S) and fracture length (Lh) with the relation S ≈ 0.15 Lh. Once the hooking is initiated, with the fracture deviation length (L) L ≈ 0.4 Lh, the fractures reaches the linkage stage only when the spacing is reduced to S ≈ 0.02 Lh and the convergence (C) is < 0.1 L. These conditions apply to multi-scale fractures with a shape ratio L/S = 10 and for fracture curvature of 10°-20°.

  12. 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.

  13. Influence of structures on fracture and fracture toughness of cemented tungsten carbides

    International Nuclear Information System (INIS)

    Zhao, W.; Zhang, X.

    1987-01-01

    A study was made of the influence of structures on fracture and fracture toughness of cemented tungsten carbides with different compositions and grain sizes. The measurement of the fracture toughness of cemented tungsten carbide was carried out using single edge notched beam. The microstructural parameters and the proportion for each fracture mode on the fracture surface were obtained. The brittle fracture of the alloy is mainly due to the interfacial decohesion fracture following the interface of the carbide crystals. It has been observed that there are localized fractures region ahead of the crack tip. The morphology of the crack propagation path as well as the slip structure in the cobalt phase of the deformed region have been investigated. In addition, a study of the correlation between the plane strain fracture toughness and microstructural parameters, such as mean free path of the cobalt phase, tungsten carbide grain size and the contiguity of tungsten carbide crystals was also made

  14. Fracture sacrum.

    Directory of Open Access Journals (Sweden)

    Dogra A

    1995-04-01

    Full Text Available An extremely rare case of combined transverse and vertical fracture of sacrum with neurological deficit is reported here with a six month follow-up. The patient also had an L1 compression fracture. The patient has recovered significantly with conservative management.

  15. Fracture Mechanics

    CERN Document Server

    Zehnder, Alan T

    2012-01-01

    Fracture mechanics is a vast and growing field. This book develops the basic elements needed for both fracture research and engineering practice. The emphasis is on continuum mechanics models for energy flows and crack-tip stress- and deformation fields in elastic and elastic-plastic materials. In addition to a brief discussion of computational fracture methods, the text includes practical sections on fracture criteria, fracture toughness testing, and methods for measuring stress intensity factors and energy release rates. Class-tested at Cornell, this book is designed for students, researchers and practitioners interested in understanding and contributing to a diverse and vital field of knowledge. Alan Zehnder joined the faculty at Cornell University in 1988. Since then he has served in a number of leadership roles including Chair of the Department of Theoretical and Applied Mechanics, and Director of the Sibley School of Mechanical and Aerospace Engineering.  He teaches applied mechanics and his research t...

  16. Elastic plastic fracture mechanics

    International Nuclear Information System (INIS)

    Simpson, L.A.

    1978-07-01

    The application of linear elastic fracture mechanics (LEFM) to crack stability in brittle structures is now well understood and widely applied. However, in many structural materials, crack propagation is accompanied by considerable crack-tip plasticity which invalidates the use of LEFM. Thus, present day research in fracture mechanics is aimed at developing parameters for predicting crack propagation under elastic-plastic conditions. These include critical crack-opening-displacement methods, the J integral and R-curve techniques. This report provides an introduction to these concepts and gives some examples of their applications. (author)

  17. Possible factors for ankle fractures

    Directory of Open Access Journals (Sweden)

    Tabaković Dejan

    2010-01-01

    Full Text Available Background/Aim. Classification of ankle fractures is commonly used for selecting an appropriate treatment and prognosing an outcome of definite management. One of the most used classifications is the Danis-Weber classification. To the best of our knowledge, in the available literature, there are no parameters affecting specific types of ankle fractures according to the Danis-Weber classification. The aim of this study was to analyze the correlation of the following parameters: age, body weight, body mass index (BMI, height, osteoporosis, osteopenia and physical exercises with specific types of ankle fractures using the Danis-Weber classification. Methods. A total of 85 patients grouped by the Danis-Weber classification fracture types were analyzed and the significance of certain parameters for specific types of ankle fractures was established. Results. The proportion of females was significantly higher (p < 0.001 with a significantly higher age (59.9 years, SD ± 14.2 in relation to males (45.1 years, SD ± 12.8 (p < 0.0001. Type A fracture was most frequent in the younger patients (34.2 years, SD ± 8.6, and those with increased physical exercises (p = 0.020. In type B fracture, the risk factor was osteoporosis (p = 0.0180, while in type C fracture, body weight (p = 0.017 and osteoporosis (p = 0.004 were significant parameters. Conclusion. Statistical analysis using the Danis-Weber classification reveals that there are certain parameters suggesting significant risk factors for specific types of ankle fractures.

  18. Effects of fracture distribution and length scale on the equivalent continuum elastic compliance of fractured rock masses

    Directory of Open Access Journals (Sweden)

    Marte Gutierrez

    2015-12-01

    Full Text Available Fracture systems have strong influence on the overall mechanical behavior of fractured rock masses due to their relatively lower stiffness and shear strength than those of the rock matrix. Understanding the effects of fracture geometrical distribution, such as length, spacing, persistence and orientation, is important for quantifying the mechanical behavior of fractured rock masses. The relation between fracture geometry and the mechanical characteristics of the fractured rock mass is complicated due to the fact that the fracture geometry and mechanical behaviors of fractured rock mass are strongly dependent on the length scale. In this paper, a comprehensive study was conducted to determine the effects of fracture distribution on the equivalent continuum elastic compliance of fractured rock masses over a wide range of fracture lengths. To account for the stochastic nature of fracture distributions, three different simulation techniques involving Oda's elastic compliance tensor, Monte Carlo simulation (MCS, and suitable probability density functions (PDFs were employed to represent the elastic compliance of fractured rock masses. To yield geologically realistic results, parameters for defining fracture distributions were obtained from different geological fields. The influence of the key fracture parameters and their relations to the overall elastic behavior of the fractured rock mass were studied and discussed. A detailed study was also carried out to investigate the validity of the use of a representative element volume (REV in the equivalent continuum representation of fractured rock masses. A criterion was also proposed to determine the appropriate REV given the fracture distribution of the rock mass.

  19. Fracture mechanics

    CERN Document Server

    Perez, Nestor

    2017-01-01

    The second edition of this textbook includes a refined presentation of concepts in each chapter, additional examples; new problems and sections, such as conformal mapping and mechanical behavior of wood; while retaining all the features of the original book. The material included in this book is based upon the development of analytical and numerical procedures pertinent to particular fields of linear elastic fracture mechanics (LEFM) and plastic fracture mechanics (PFM), including mixed-mode-loading interaction. The mathematical approach undertaken herein is coupled with a brief review of several fracture theories available in cited references, along with many color images and figures. Dynamic fracture mechanics is included through the field of fatigue and Charpy impact testing. Explains computational and engineering approaches for solving crack-related problems using straightforward mathematics that facilitate comprehension of the physical meaning of crack growth processes; Expands computational understandin...

  20. 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

  1. Facial Fractures.

    Science.gov (United States)

    Ricketts, Sophie; Gill, Hameet S; Fialkov, Jeffery A; Matic, Damir B; Antonyshyn, Oleh M

    2016-02-01

    After reading this article, the participant should be able to: 1. Demonstrate an understanding of some of the changes in aspects of facial fracture management. 2. Assess a patient presenting with facial fractures. 3. Understand indications and timing of surgery. 4. Recognize exposures of the craniomaxillofacial skeleton. 5. Identify methods for repair of typical facial fracture patterns. 6. Discuss the common complications seen with facial fractures. Restoration of the facial skeleton and associated soft tissues after trauma involves accurate clinical and radiologic assessment to effectively plan a management approach for these injuries. When surgical intervention is necessary, timing, exposure, sequencing, and execution of repair are all integral to achieving the best long-term outcomes for these patients.

  2. Pisiform fractures

    International Nuclear Information System (INIS)

    Fleege, M.A.; Jebson, P.J.; Renfrew, D.L.; El-Khoury, G.Y.; Steyers, C.M. Jr.

    1991-01-01

    Fractures of the pisiform are often missed due to improper radiographic evaluation and a tendency to focus on other, more obvious injuries. Delayed diagnosis may result in disabling sequelae. A high index of clinical suspicion and appropriate radiographic examination will establish the correct diagnosis. Ten patients with pisiform fracture are presented. The anatomy, mechanism of injury, clinical presentation, radiographic features, and evaluation of this injury are discussed. (orig.)

  3. Stress fractures

    International Nuclear Information System (INIS)

    Berquist, T.H.; Cooper, K.L.; Pritchard, D.J.

    1985-01-01

    The diagnosis of a stress fracture should be considered in patients presented with pain after a change in activity, especially if the activity is strenuous and the pain is in the lower extremities. Since evidence of the stress fracture may not be apparent for weeks on routine radiographs, proper use of other imaging techniques will allow an earlier diagnosis. Prompt diagnosis is especially important in the femur, where displacement may occur

  4. Scaphoid Fracture

    Directory of Open Access Journals (Sweden)

    Esther Kim, BS

    2018-04-01

    Full Text Available History of present illness: A 25-year-old, right-handed male presented to the emergency department with left wrist pain after falling from a skateboard onto an outstretched hand two-weeks prior. He otherwise had no additional concerns, including no complaints of weakness or loss of sensation. On physical exam, there was tenderness to palpation within the anatomical snuff box. The neurovascular exam was intact. Plain films of the left wrist and hand were obtained. Significant findings: The anteroposterior (AP plain film of this patient demonstrates a full thickness fracture through the middle third of the scaphoid (red arrow, with some apparent displacement (yellow lines and subtle angulation of the fracture fragments (blue line. Discussion: The scaphoid bone is the most commonly fractured carpal bone accounting for 70%-80% of carpal fractures.1 Classically, it is sustained following a fall onto an outstretched hand (FOOSH. Patients should be evaluated for tenderness with palpation over the anatomical snuffbox, which has a sensitivity of 100% and specificity of 40%.2 Plain films are the initial diagnostic modality of choice and have a sensitivity of 70%, but are commonly falsely negative in the first two to six weeks of injury (false negative of 20%.3 The Mayo classification organizes scaphoid fractures as involving the proximal, mid, and distal portions of the scaphoid bone with mid-fractures being the most common.3 The proximal scaphoid is highly susceptible to vascular compromise because it depends on retrograde blood flow from the radial artery. Therefore, disruption can lead to serious sequelae including osteonecrosis, arthrosis, and functional impairment. Thus, a low threshold should be maintained for neurovascular evaluation and surgical referral. Patients with non-displaced scaphoid fractures should be placed in a thumb spica splint.3 Patients with even suspected scaphoid fractures should be placed in a thumb spica splint and re

  5. Simulation of complex fracture networks influenced by natural fractures in shale gas reservoir

    Directory of Open Access Journals (Sweden)

    Zhao Jinzhou

    2014-10-01

    Full Text Available When hydraulic fractures intersect with natural fractures, the geometry and complexity of a fracture network are determined by the initiation and propagation pattern which is affected by a number of factors. Based on the fracture mechanics, the criterion for initiation and propagation of a fracture was introduced to analyze the tendency of a propagating angle and factors affecting propagating pressure. On this basis, a mathematic model with a complex fracture network was established to investigate how the fracture network form changes with different parameters, including rock mechanics, in-situ stress distribution, fracture properties, and frac treatment parameters. The solving process of this model was accelerated by classifying the calculation nodes on the extending direction of the fracture by equal pressure gradients, and solving the geometrical parameters prior to the iteration fitting flow distribution. With the initiation and propagation criterion as the bases for the propagation of branch fractures, this method decreased the iteration times through eliminating the fitting of the fracture length in conventional 3D fracture simulation. The simulation results indicated that the formation with abundant natural fractures and smaller in-situ stress difference is sufficient conditions for fracture network development. If the pressure in the hydraulic fractures can be kept at a high level by temporary sealing or diversion, the branch fractures will propagate further with minor curvature radius, thus enlarging the reservoir stimulation area. The simulated shape of fracture network can be well matched with the field microseismic mapping in data point range and distribution density, validating the accuracy of this model.

  6. Quantifying Discrete Fracture Network Connectivity in Hydraulic Fracturing Stimulation

    Science.gov (United States)

    Urbancic, T.; Ardakani, E. P.; Baig, A.

    2017-12-01

    Hydraulic fracture stimulations generally result in microseismicity that is associated with the activation or extension of pre-existing microfractures and discontinuities. Microseismic events acquired under 3D downhole sensor coverage provide accurate event locations outlining hydraulic fracture growth. Combined with source characteristics, these events provide a high quality input for seismic moment tensor inversion and eventually constructing the representative discrete fracture network (DFN). In this study, we investigate the strain and stress state, identified fracture orientation, and DFN connectivity and performance for example stages in a multistage perf and plug completion in a North American shale play. We use topology, the familiar concept in many areas of structural geology, to further describe the relationships between the activated fractures and their effectiveness in enhancing permeability. We explore how local perturbations of stress state lead to the activation of different fractures sets and how that effects the DFN interaction and complexity. In particular, we observe that a more heterogeneous stress state shows a higher percentage of sub-horizontal fractures or bedding plane slips. Based on topology, the fractures are evenly distributed from the injection point, with decreasing numbers of connections by distance. The dimensionless measure of connection per branch and connection per line are used for quantifying the DFN connectivity. In order to connect the concept of connectivity back to productive volume and stimulation efficiency, the connectivity is compared with the character of deformation in the reservoir as deduced from the collective behavior of microseismicity using robustly determined source parameters.

  7. A six-year retrospective analysis of cut-out risk predictors in cephalomedullary nailing for pertrochanteric fractures: Can the tip-apex distance (TAD) still be considered the best parameter?

    Science.gov (United States)

    Caruso, G; Bonomo, M; Valpiani, G; Salvatori, G; Gildone, A; Lorusso, V; Massari, L

    2017-08-01

    Intramedullary fixation is considered the most stable treatment for pertrochanteric fractures of the proximal femur and cut-out is one of the most frequent mechanical complications. In order to determine the role of clinical variables and radiological parameters in predicting the risk of this complication, we analysed the data pertaining to a group of patients recruited over the course of six years. A total of 571 patients were included in this study, which analysed the incidence of cut-out in relation to several clinical variables: age; gender; the AO Foundation and Orthopaedic Trauma Association classification system (AO/OTA); type of nail; cervical-diaphyseal angle; surgical wait times; anti-osteoporotic medication; complete post-operative weight bearing; and radiological parameters (namely the lag-screw position with respect to the femoral head, the Cleveland system, the tip-apex distance (TAD), and the calcar-referenced tip-apex distance (CalTAD)). The incidence of cut-out across the sample was 5.6%, with a higher incidence in female patients. A significantly higher risk of this complication was correlated with lag-screw tip positioning in the upper part of the femoral head in the anteroposterior radiological view, posterior in the latero-lateral radiological view, and in the Cleveland peripheral zones. The tip-apex distance and the calcar-referenced tip-apex distance were found to be highly significant predictors of the risk of cut-out at cut-offs of 30.7 mm and 37.3 mm, respectively, but the former appeared more reliable than the latter in predicting the occurrence of this complication. The tip-apex distance remains the most accurate predictor of cut-out, which is significantly greater above a cut-off of 30.7 mm. Cite this article: G. Caruso, M. Bonomo, G. Valpiani, G. Salvatori, A. Gildone, V. Lorusso, L. Massari. A six-year retrospective analysis of cut-out risk predictors in cephalomedullary nailing for pertrochanteric fractures: Can the tip-apex distance

  8. Hydrologic behavior of fracture networks

    International Nuclear Information System (INIS)

    Long, J.C.S.; Endo, H.K.; Karasaki, K.; Pyrak, L.; MacLean, P.; Witherspoon, P.A.

    1984-10-01

    This paper reviews recent research on the nature of flow and transport in discontinuous fracture networks. The hydrologic behavior of these networks has been examined using two- and three-dimensional numerical models. The numerical models represent random realizations of fracture networks based on statistical field measurements of fracture geometry and equivalent hydraulic aperture. We have compared the flux and mechanical transport behavior of these networks to the behavior of equivalent continua. In this way we are able to determine whether a given fracture network can be modeled as an equivalent porous media in both flux and advective transport studies. We have examined departures from porous media behavior both as a function of interconnectivity and heterogeneity. Parameter studies have revealed behavior patterns such as: given a fracture frequency that can be measured in the field, porous media like behavior and the magnitude of permeability are both enhanced if the fractures are longer and the standard deviation of fracture permeabilities is smaller. Transport studies have shown that the ratio between flux and velocity is not necessarily constant when the direction of flow is changed in systems which do behave like a porous media for flux. Thus the conditions under which porous media analysis can be used in transport studies are more restrictive than the condition for flux studies. We have examined systems which do not behave like porous media and have shown how the in situ behavior varies as a function of scale of observation. The behavior of well tests in fractured networks has been modeled and compared to a new analytical well test solution which accounts for the early time dominance of the fractures intersecting the well. Finally, a three-dimensional fracture flow model has been constructed which assumes fractures are randomly located discs. 13 references, 12 figures

  9. Sternal fractures and their management

    Directory of Open Access Journals (Sweden)

    Al-achraf Khoriati

    2013-01-01

    Full Text Available Sternal fractures are predominantly associated with deceleration injuries and blunt anterior chest trauma. Sternal trauma must be carefully evaluated by monitoring of vital parameters and it is of paramount importance that concomitant injuries are excluded. Nevertheless, routine admission of patients with isolated sternal fractures for observation is still common in today′s practice, which is often unnecessary. This article aims to describe the prognosis, the recommended assessment and management of patients with sternal fractures, to help clinicians make an evidence-based judgment regarding the need for hospitalization.

  10. Flow and transport in hierarchically fractured systems

    International Nuclear Information System (INIS)

    Karasaki, K.

    1993-01-01

    Preliminary results indicate that flow in the saturated zone at Yucca Mountain is controlled by fractures. A current conceptual model assumes that the flow in the fracture system can be approximately by a three-dimensionally interconnected network of linear conduits. The overall flow system of rocks at Yucca Mountain is considered to consist of hierarchically structured heterogeneous fracture systems of multiple scales. A case study suggests that it is more appropriate to use the flow parameters of the large fracture system for predicting the first arrival time, rather than using the bulk average parameters of the total system

  11. Prediction of fracture parameters of circumferential through-wall cracks in the interface between an elbow and a pipe under internal pressure

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Youn Young; Huh, Nam Su [Dept. of Mechanical System Design Engineering, Seoul National Univ. of Science and Technology, Seoul (Korea, Republic of); Jeong, Jae Uk [Doosan Heavy Industries and Construction, Changwon (Korea, Republic of)

    2016-09-15

    This paper provides plastic influence functions of GE/EPRI method for calculating J and Crack opening displacement (COD) of pipes with a circumferential Through-wall crack (TWC) in the interface between an elbow and a straight pipe by using 3-dimensional (3-D) elastic-plastic finite element analyses for Ramberg-Osgood (R-O) materials, in which internal pressure was considered as a loading condition. The proposed plastic influence functions are tabulated as a function of the pipe geometries, crack length and strain hardening exponent. In order to provide sufficient confidence for the proposed plastic influence functions, the estimation scheme using the proposed plastic influence functions for J and COD of cracked elbows was validated against FE results using R-O parameters for the SA312 TP316 stainless steel. Moreover, the predicted J and COD for elbows with a TWC in the interface between an elbow and a pipe by the proposed scheme were compared with those for cracked straight pipes to investigate the effect of the elbow geometries on crack behavior of elbows. One important point is that crack behaviors in the interface between an elbow and a straight pipe can be significantly different with those in straight pipes according to pipe thickness, crack length and bend radius of elbows. Thus, the proposed plastic influence functions can be useful to predict accurate J and COD for cracked elbows.

  12. Prediction of fracture parameters of circumferential through-wall cracks in the interface between an elbow and a pipe under internal pressure

    International Nuclear Information System (INIS)

    Jang, Youn Young; Huh, Nam Su; Jeong, Jae Uk

    2016-01-01

    This paper provides plastic influence functions of GE/EPRI method for calculating J and Crack opening displacement (COD) of pipes with a circumferential Through-wall crack (TWC) in the interface between an elbow and a straight pipe by using 3-dimensional (3-D) elastic-plastic finite element analyses for Ramberg-Osgood (R-O) materials, in which internal pressure was considered as a loading condition. The proposed plastic influence functions are tabulated as a function of the pipe geometries, crack length and strain hardening exponent. In order to provide sufficient confidence for the proposed plastic influence functions, the estimation scheme using the proposed plastic influence functions for J and COD of cracked elbows was validated against FE results using R-O parameters for the SA312 TP316 stainless steel. Moreover, the predicted J and COD for elbows with a TWC in the interface between an elbow and a pipe by the proposed scheme were compared with those for cracked straight pipes to investigate the effect of the elbow geometries on crack behavior of elbows. One important point is that crack behaviors in the interface between an elbow and a straight pipe can be significantly different with those in straight pipes according to pipe thickness, crack length and bend radius of elbows. Thus, the proposed plastic influence functions can be useful to predict accurate J and COD for cracked elbows

  13. Applicability of geostatistical procedures for the evaluation of hydrogeological parameters of a fractured aquifer in the Ronneburg mine district; Anwendbarkeit geostatistischer Verfahren zur Beurteilung hydrogeologischer Parameter eines heterogenen Kluftaquifers im Ronneburger Bergbaurevier

    Energy Technology Data Exchange (ETDEWEB)

    Grasshoff, C.; Schetelig, K. [RWTH Aachen, Lehrstuhl fuer Ingenieurgeologie und Hydrogeologie (Germany); Tomschi, H. [Harress Pickel Consult GmbH, Huerth (Germany)

    1998-12-31

    The following paper demonstrates, how a geostatistical approach can help interpolating hydrogeological parameters over a certain area. The basic elements developed by G. Matheron in the sixties are represented as the preconditions and assumptions, which provide the best results of the estimation. The variogram as the most important tool in geostatistics offers the opportunity to describe the correlating behaviour of a regionalized variable. Some kriging procedures are briefly introduced, which provide under varying circumstances estimating of non-measured values with the theoretical variogram-model. In the Ronneburg mine district 108 screened drill-holes could provide coefficients of hydraulic conductivity. These were interpolated with ordinary kriging over the whole investigation area. An error calculation was performed, which could prove the accuracy of the estimation. Short prospects point out some difficulties handling with geostatistic procedures and make suggestions for further investigations. (orig.) [Deutsch] Der folgende Artikel soll aufzeigen, inwiefern ein geostatistischer Ansatz hilfreich ist, um hydrogeologische Parameter flaechenhaft zu interpolieren. Dabei werden die von Matheron in den sechziger Jahren entwickelten Grundlagen vorgestellt und die Voraussetzungen definiert, unter denen die geostatistischen Schaetzmethoden die besten Ergebnisse liefern. Das Variogramm, als wichtigstes Werkzeug, bietet die Moeglichkeit, die raeumliche Korrelation der untersuchten Variable zu belegen. Mehrere Kriging-Verfahren werden skizzenhaft vorgestellt, die es unter unterschiedlichen Voraussetzungen ermoeglichen, an den Stellen des Untersuchungsgebietes, wo keine Messungen vorliegen, Schaetzungen aus dem Variogramm-Modell zu errechnen. Im Ronneburger Bergbaugebiet wurden aus 108 verfilterten Bohrungen k{sub f}-Werte gewonnen, die mittels Ordinary Kriging flaechenhaft ueber das gesamte Untersuchungsgebiet interpoliert wurden. Eine Fehlerabschaetzung gibt ueber die

  14. Trochanteric fractures

    International Nuclear Information System (INIS)

    Herrlin, K.; Stroemberg, T.; Lidgren, L.; Walloee, A.; Pettersson, H.; Lund Univ.

    1988-01-01

    Four hundred and thirty trochanteric factures operated upon with McLaughlin, Ender or Richard's osteosynthesis were divided into 6 different types based on their radiographic appearance before and immediately after reposition with special reference to the medial cortical support. A significant correlation was found between the fracture type and subsequent mechanical complications where types 1 and 2 gave less, and types 4 and 5 more complications. A comparison of the various osteosyntheses showed that Richard's had significantly fewer complications than either the Ender or McLaughlin types. For Richard's osteosynthesis alone no correlation to fracture type could be made because of the small number of complications in this group. (orig.)

  15. Fracture Blisters

    Directory of Open Access Journals (Sweden)

    Uebbing, Claire M

    2011-02-01

    Full Text Available Fracture blisters are a relatively uncommon complication of fractures in locations of the body, such as the ankle, wrist elbow and foot, where skin adheres tightly to bone with little subcutaneous fat cushioning. The blister that results resembles that of a second degree burn.These blisters significantly alter treatment, making it difficult to splint or cast and often overlying ideal surgical incision sites. Review of the literature reveals no consensus on management; however, most authors agree on early treatment prior to blister formation or delay until blister resolution before attempting surgical correction or stabilization. [West J Emerg Med. 2011;12(1;131-133.

  16. Elbow Fractures

    Science.gov (United States)

    ... is also an important factor when treating elbow fractures. Casts are used more frequently in children, as their risk of developing elbow stiffness is small; however, in an adult, elbow stiffness is much more likely. Rehabilitation directed by your doctor is often used to ...

  17. Wrist Fractures

    Science.gov (United States)

    ... All Topics A-Z Videos Infographics Symptom Picker Anatomy Bones Joints Muscles Nerves Vessels Tendons About Hand Surgery What is a Hand Surgeon? What is a Hand Therapist? Media Find a Hand Surgeon Home Anatomy Wrist Fractures Email to a friend * required fields ...

  18. Shoulder Fractures

    Science.gov (United States)

    ... All Topics A-Z Videos Infographics Symptom Picker Anatomy Bones Joints Muscles Nerves Vessels Tendons About Hand Surgery What is a Hand Surgeon? What is a Hand Therapist? Media Find a Hand Surgeon Home Anatomy Shoulder Fractures Email to a friend * required fields ...

  19. Simulation of counter-current imbibition in water-wet fractured reservoirs based on discrete-fracture model

    Directory of Open Access Journals (Sweden)

    Wang Yueying

    2017-08-01

    Full Text Available Isolated fractures usually exist in fractured media systems, where the capillary pressure in the fracture is lower than that of the matrix, causing the discrepancy in oil recoveries between fractured and non-fractured porous media. Experiments, analytical solutions and conventional simulation methods based on the continuum model approach are incompetent or insufficient in describing media containing isolated fractures. In this paper, the simulation of the counter-current imbibition in fractured media is based on the discrete-fracture model (DFM. The interlocking or arrangement of matrix and fracture system within the model resembles the traditional discrete fracture network model and the hybrid-mixed-finite-element method is employed to solve the associated equations. The Behbahani experimental data validates our simulation solution for consistency. The simulation results of the fractured media show that the isolated-fractures affect the imbibition in the matrix block. Moreover, the isolated fracture parameters such as fracture length and fracture location influence the trend of the recovery curves. Thus, the counter-current imbibition behavior of media with isolated fractures can be predicted using this method based on the discrete-fracture model.

  20. 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.

  1. 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.

  2. Description of Fracture Systems for External Criticality Reports

    International Nuclear Information System (INIS)

    Nicot, Jean-Philippe

    2001-01-01

    The purpose of this Analysis/Model Report (AMR) is to describe probabilistically the main features of the geometry of the fracture system in the vicinity of the repository. They will be used to determine the quantity of fissile material that could accumulate in the fractured rock underneath a waste package as it degrades. This AMR is to feed the geochemical calculations for external criticality reports. This AMR is done in accordance with the technical work plan (BSC (Bechtel SAIC Company) 2001 b). The scope of this AMR is restricted to the relevant parameters of the fracture system. The main parameters of interest are fracture aperture and fracture spacing distribution parameters. The relative orientation of the different fracture sets is also important because of its impact on criticality, but they will be set deterministically. The maximum accumulation of material depends primarily on the fracture porosity, combination of the fracture aperture, and fracture intensity. However, the fracture porosity itself is not sufficient to characterize the potential for accumulation of a fracture system. The fracture aperture is also important because it controls both the flow through the fracture and the potential plugging of the system. Other features contributing to the void space such as lithophysae are also investigated. On the other hand, no analysis of the matrix porosity is done. The parameters will be used in sensitivity analyses of geochemical calculations providing actinide accumulations and in the subsequent Monte Carlo criticality analyses

  3. 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)

  4. Bimalleolar ankle fracture with proximal fibular fracture

    NARCIS (Netherlands)

    Colenbrander, R. J.; Struijs, P. A. A.; Ultee, J. M.

    2005-01-01

    A 56-year-old female patient suffered a bimalleolar ankle fracture with an additional proximal fibular fracture. This is an unusual fracture type, seldom reported in literature. It was operatively treated by open reduction and internal fixation of the lateral malleolar fracture. The proximal fibular

  5. Tensile and fracture behavior of polymer foams

    International Nuclear Information System (INIS)

    Kabir, Md. E.; Saha, M.C.; Jeelani, S.

    2006-01-01

    Tensile and mode-I fracture behavior of cross-linked polyvinyl chloride (PVC) and rigid polyurethane (PUR) foams are examined. Tension tests are performed using prismatic bar specimens and mode-I fracture tests are performed using single edge notched bend (SENB) specimens under three-point bending. Test specimens are prepared from PVC foams with three densities and two different levels of cross-linking, and PUR foam with one density. Tension and quasi-static fracture tests are performed using a Zwick/Rowell test machine. Dynamic fracture tests are performed using a DYNATUP model 8210 instrumented drop-tower test set up at three different impact energy levels. Various parameters such as specimen size, loading rate, foam density, cross-linking, crack length, cell orientation (flow and rise-direction) and solid polymer material are studied. It is found that foam density and solid polymer material have a significant effect on tensile strength, modulus, and fracture toughness of polymer foams. Level of polymer cross-linking is also found to have a significant effect on fracture toughness. The presence of cracks in the rise- and flow direction as well as loading rate has minimal effect. Dynamic fracture behavior is found to be different as compared to quasi-static fracture behavior. Dynamic fracture toughness (K d ) increases with impact energy. Examination of fracture surfaces reveals that the fracture occurs in fairly brittle manner for all foam materials

  6. Near Wellbore Hydraulic Fracture Propagation from Perforations in Tight Rocks: The Roles of Fracturing Fluid Viscosity and Injection Rate

    Directory of Open Access Journals (Sweden)

    Seyed Hassan Fallahzadeh

    2017-03-01

    Full Text Available Hydraulic fracture initiation and near wellbore propagation is governed by complex failure mechanisms, especially in cased perforated wellbores. Various parameters affect such mechanisms, including fracturing fluid viscosity and injection rate. In this study, three different fracturing fluids with viscosities ranging from 20 to 600 Pa.s were used to investigate the effects of varying fracturing fluid viscosities and fluid injection rates on the fracturing mechanisms. Hydraulic fracturing tests were conducted in cased perforated boreholes made in tight 150 mm synthetic cubic samples. A true tri-axial stress cell was used to simulate real far field stress conditions. In addition, dimensional analyses were performed to correspond the results of lab experiments to field-scale operations. The results indicated that by increasing the fracturing fluid viscosity and injection rate, the fracturing energy increased, and consequently, higher fracturing pressures were observed. However, when the fracturing energy was transferred to a borehole at a faster rate, the fracture initiation angle also increased. This resulted in more curved fracture planes. Accordingly, a new parameter, called fracturing power, was introduced to relate fracture geometry to fluid viscosity and injection rate. Furthermore, it was observed that the presence of casing in the wellbore impacted the stress distribution around the casing in such a way that the fracture propagation deviated from the wellbore vicinity.

  7. Fracture mechanics

    International Nuclear Information System (INIS)

    Miannay, D.P.

    1995-01-01

    This book entitle ''Fracture Mechanics'', the first one of the monograph ''Materiologie'' is geared to design engineers, material engineers, non destructive inspectors and safety experts. This book covers fracture mechanics in isotropic homogeneous continuum. Only the monotonic static loading is considered. This book intended to be a reference with the current state of the art gives the fundamental of the issues under concern and avoids the developments too complicated or not yet mastered for not making reading cumbersome. The subject matter is organized as going from an easy to a more complicated level and thus follows the chronological evolution in the field. Similarly the microscopic scale is considered before the macroscopic scale, the physical understanding of phenomena linked to the experimental observation of the material preceded the understanding of the macroscopic behaviour of structures. In this latter field the relatively recent contribution of finite element computations with some analogy with the experimental observation is determining. However more sensitive analysis is not skipped

  8. Crack propagation and fracture in silicon carbide

    International Nuclear Information System (INIS)

    Evans, A.G.; Lange, F.F.

    1975-01-01

    Fracture mechanics and strength studies performed on two silicon carbides - a hot-pressed material (with alumina) and a sintered material (with boron) - have shown that both materials exhibit slow crack growth at room temperature in water, but only the hot-pressed material exhibits significant high temperature slow crack growth (1000 to 1400 0 C). A good correlation of the observed fracture behaviour with the crack growth predicted from the fracture mechanics parameters shows that effective failure predictions for this material can be achieved using macro-fracture mechanics data. (author)

  9. 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.

  10. Test techniques for fracture mechanics testing

    International Nuclear Information System (INIS)

    Schwalbe, K.H.

    1980-01-01

    Test methods for fracture mechanics tests are described. Two groups of techniques are distinguished: Those for measurement of stable crack growth and those for determination of the loading parameters. (orig.) [de

  11. Assessing alternative conceptual models of fracture flow

    International Nuclear Information System (INIS)

    Ho, C.K.

    1995-01-01

    The numerical code TOUGH2 was used to assess alternative conceptual models of fracture flow. The models that were considered included the equivalent continuum model (ECM) and the dual permeability (DK) model. A one-dimensional, layered, unsaturated domain was studied with a saturated bottom boundary and a constant infiltration at the top boundary. Two different infiltration rates were used in the studies. In addition, the connection areas between the fracture and matrix elements in the dual permeability model were varied. Results showed that the two conceptual models of fracture flow produced different saturation and velocity profiles-even under steady-state conditions. The magnitudes of the discrepancies were sensitive to two parameters that affected the flux between the fractures and matrix in the dual permeability model: (1) the fracture-matrix connection areas and (2) the capillary pressure gradients between the fracture and matrix elements

  12. Evaluation of scale effects on hydraulic characteristics of fractured rock using fracture network model

    International Nuclear Information System (INIS)

    Ijiri, Yuji; Sawada, Atsushi; Uchida, Masahiro; Ishiguro, Katsuhiko; Umeki, Hiroyuki; Sakamoto, Kazuhiko; Ohnishi, Yuzo

    2001-01-01

    It is important to take into account scale effects on fracture geometry if the modeling scale is much larger than the in-situ observation scale. The scale effect on fracture trace length, which is the most scale dependent parameter, is investigated using fracture maps obtained at various scales in tunnel and dam sites. We found that the distribution of fracture trace length follows negative power law distribution in regardless of locations and rock types. The hydraulic characteristics of fractured rock is also investigated by numerical analysis of discrete fracture network (DFN) model where power law distribution of fracture radius is adopted. We found that as the exponent of power law distribution become larger, the hydraulic conductivity of DFN model increases and the travel time in DFN model decreases. (author)

  13. 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.

  14. Hip fracture - discharge

    Science.gov (United States)

    ... neck fracture repair - discharge; Trochanteric fracture repair - discharge; Hip pinning surgery - discharge ... in the hospital for surgery to repair a hip fracture, a break in the upper part of ...

  15. Toughness-Dominated Regime of Hydraulic Fracturing in Cohesionless Materials

    Science.gov (United States)

    Germanovich, L. N.; Hurt, R. S.; Ayoub, J.; Norman, W. D.

    2011-12-01

    This work examines the mechanisms of hydraulic fracturing in cohesionless particulate materials with geotechnical, geological, and petroleum applications. For this purpose, experimental techniques have been developed, and used to quantify the initiation and propagation of hydraulic fractures in saturated particulate materials. The fracturing liquid is injected into particulate materials, which are practically cohesionless. The liquid flow is localized in thin self-propagating crack-like conduits. By analogy we call them 'cracks' or 'hydraulic fractures.' When a fracture propagates in a solid, new surfaces are created by breaking material bonds. Consequently, the material is in tension at the fracture tip. Because the particulate material is already 'fractured,' no new surface is created and no fracturing process per se is involved. Therefore, the conventional fracture mechanics principles cannot be directly applied. Based on the laboratory observations, performed on three particulate materials (Georgia Red Clay, silica flour, and fine sand, and their mixtures), this work offers physical concepts to explain the observed phenomena. The goal is to determine the controlling parameters of fracture behavior and to quantify their effects. An important conclusion of our work is that all parts of the cohesionless particulate material (including the tip zone of hydraulic fracture) are likely to be in compression. The compressive stress state is an important characteristic of hydraulic fracturing in particulate materials with low, or no, cohesion (such as were used in our experiments). At present, two kinematic mechanisms of fracture propagation, consistent with the compressive stress regime, can be offered. The first mechanism is based on shear bands propagating ahead of the tip of an open fracture. The second is based on the tensile strain ahead of the fracture tip and reduction of the effective stresses to zero within the leak-off zone. Scaling indicates that in our

  16. Micromechanics of fracture in WC-Co hardmetals

    International Nuclear Information System (INIS)

    Dusza, J.; Parilak, L.

    1986-01-01

    A study has been made in WC-Co cemented carbides with grain sizes of 2.1 - 3.6 μm and 13 - 32 vol% Co, of the relationship between the fracture toughness and microstructural parameters and micromechanisms of fracture. Regression analyses have been used to derive empirical relationships between fracture toughness, and the binder spacing, the contiguity and the relative proportions of fracture in the binder phase and between contiguous WC grains

  17. Surrogate-based optimization of hydraulic fracturing in pre-existing fracture networks

    Science.gov (United States)

    Chen, Mingjie; Sun, Yunwei; Fu, Pengcheng; Carrigan, Charles R.; Lu, Zhiming; Tong, Charles H.; Buscheck, Thomas A.

    2013-08-01

    Hydraulic fracturing has been used widely to stimulate production of oil, natural gas, and geothermal energy in formations with low natural permeability. Numerical optimization of fracture stimulation often requires a large number of evaluations of objective functions and constraints from forward hydraulic fracturing models, which are computationally expensive and even prohibitive in some situations. Moreover, there are a variety of uncertainties associated with the pre-existing fracture distributions and rock mechanical properties, which affect the optimized decisions for hydraulic fracturing. In this study, a surrogate-based approach is developed for efficient optimization of hydraulic fracturing well design in the presence of natural-system uncertainties. The fractal dimension is derived from the simulated fracturing network as the objective for maximizing energy recovery sweep efficiency. The surrogate model, which is constructed using training data from high-fidelity fracturing models for mapping the relationship between uncertain input parameters and the fractal dimension, provides fast approximation of the objective functions and constraints. A suite of surrogate models constructed using different fitting methods is evaluated and validated for fast predictions. Global sensitivity analysis is conducted to gain insights into the impact of the input variables on the output of interest, and further used for parameter screening. The high efficiency of the surrogate-based approach is demonstrated for three optimization scenarios with different and uncertain ambient conditions. Our results suggest the critical importance of considering uncertain pre-existing fracture networks in optimization studies of hydraulic fracturing.

  18. Proximal femoral fractures.

    Science.gov (United States)

    Webb, Lawrence X

    2002-01-01

    Fractures of the proximal femur include fractures of the head, neck, intertrochanteric, and subtrochanteric regions. Head fractures commonly accompany dislocations. Neck fractures and intertrochanteric fractures occur with greatest frequency in elderly patients with a low bone mineral density and are produced by low-energy mechanisms. Subtrochanteric fractures occur in a predominantly strong cortical osseous region which is exposed to large compressive stresses. Implants used to address these fractures must be able to accommodate significant loads while the fractures consolidate. Complications secondary to these injuries produce significant morbidity and include infection, nonunion, malunion, decubitus ulcers, fat emboli, deep venous thrombosis, pulmonary embolus, pneumonia, myocardial infarction, stroke, and death.

  19. Laboratory testing on infiltration in single synthetic fractures

    Science.gov (United States)

    Cherubini, Claudia; Pastore, Nicola; Li, Jiawei; Giasi, Concetta I.; Li, Ling

    2017-04-01

    An understanding of infiltration phenomena in unsaturated rock fractures is extremely important in many branches of engineering for numerous reasons. Sectors such as the oil, gas and water industries are regularly interacting with water seepage through rock fractures, yet the understanding of the mechanics and behaviour associated with this sort of flow is still incomplete. An apparatus has been set up to test infiltration in single synthetic fractures in both dry and wet conditions. To simulate the two fracture planes, concrete fractures have been moulded from 3D printed fractures with varying geometrical configurations, in order to analyse the influence of aperture and roughness on infiltration. Water flows through the single fractures by means of a hydraulic system composed by an upstream and a downstream reservoir, the latter being subdivided into five equal sections in order to measure the flow rate in each part to detect zones of preferential flow. The fractures have been set at various angles of inclination to investigate the effect of this parameter on infiltration dynamics. The results obtained identified that altering certain fracture parameters and conditions produces relevant effects on the infiltration process through the fractures. The main variables influencing the formation of preferential flow are: the inclination angle of the fracture, the saturation level of the fracture and the mismatch wavelength of the fracture.

  20. Probabilistic application of fracture mechanics

    International Nuclear Information System (INIS)

    Dufresne, J.

    1981-04-01

    The different methods used to evaluate the rupture probability of a pressure vessel are reviewed. Data collection and processing of all parameters necessary for fracture mechanics evaluation are presented with particular attention to the size distribution of defects in actual vessels. Physical process is followed during crack growth and unstable propagation, using LEFM (Linear Elastic Fracture Mechanism) and plastic instability. Results show that the final failure probability for a PWR pressure vessel is 3.5 10 -8 , and is due essentially to LOCAs for any break size. The weakest point is the internal side of the belt line

  1. Correlation of nodular austempered ductile iron (ADI) microstructural parameters and fatigue properties using an approach based on fracture mechanics; Correlacao entre parametros microestruturais do ferro fundido nodular austemperado (ADI) com suas propriedades a fadiga utilizando uma abordagem baseada na mecanica de fratura

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Jose Felipe [Universidade de Itauna (UIT), MG (Brazil). Faculdade de Engenharia; Fonseca, Vinicius Rizzuti; Godefroid, Leonardo Barbosa [Universidade Federal de Ouro Preto (UFOP), MG (Brazil). Escola de Minas; Ribeiro, Gabriel de Oliveira [Universidade Federal de Minas Gerais (UFMG), MG (Brazil). Departamento de Engenharia de Estruturas

    2010-07-01

    An investigation has been accomplished to check the effect of temperature and austempering time on austempered ductile iron (ADI) properties by means of fracture toughness (K{sub C}) and fatigue threshold (∆K{sub th}) tests. The correlation of ADI microstructural parameters and ADI two mechanical parameters: KC and Kth, is evaluated. Three sets of samples have ben extracted from ADI casting Y blocks produced in industrial conditions.and austenitized at 900°C for 1.5 hour. The austempering process has been performed in the following ways: the first set was austenitized at 300 deg C for 4 hours, the second set at 360°C for 1.5 hour and the third at 360°C for 0.6 hour. These distinct austempering processes have been adopted in order to obtain distinct microstructures containing austenite with two different carbon rates and two ferritic cell sizes. The materials have been characterized by means of optical and electronic microscopy, X-ray diffraction and mechanical tests. All materials have presented equivalent fatigue crack propagation rates, fracture toughness in the range between 94 and 128 MPa·m{sup 1/2} and ∆K{sub th} in the range between 5,7 and 6,4 MPa·m{sup 1/2}. The experimental results have confirmed the effect of microstructural properties (austenitic volumetric rate, austenitic carbon rate, ferritic cell size, total matrix carbon content) on fracture toughness (K{sub C}) and fatigue threshold (∆K{sub th}). Further, it was found that following parameters: fracture toughness (K{sub C}), fatigue threshold ((∆K{sub th}) and impact strength are correlated with the total matrix carbon content and ferritic cell size. (author)

  2. Fractured Penis: Not So Rare!

    Science.gov (United States)

    Tamhankar, Ashwin S; Pawar, Prakash W; Sawant, Ajit S; Kasat, Gaurav V; Savaliya, Abhishek; Mundhe, Shankar; Patil, Sunil; Narwade, Sayalee

    2017-01-01

    Penile fracture is a relatively common phenomenon. The main problem associated with this condition is the lack of patients' awareness on the urgency of the situation. This study reports the different modes of presentations and treatment results. We reviewed 21 cases of penile fracture over 5 years. Parameters were mode of injury, age group, time interval before presentation, management, site of injury, urethral involvement, results, complications and erectile function at follow-up. The mean age of patients was 34 years, the mean time interval until presentation was 26 h. Cases involving the right corpus cavernosum comprised 57.14% and 42.85% were cases involving the left corpus cavernosum. Two patients had full circumferential urethral tear. Two patients developed wound infections and 2 patients developed mild penile curvature (40 h). Urologists need to consider penile fracture a urological emergency and atypical presentations need to be considered when deciding on management. © 2017 S. Karger AG, Basel.

  3. Fracture as a material sink

    Science.gov (United States)

    Volokh, K. Y.

    2017-12-01

    Cracks are created by massive breakage of molecular or atomic bonds. The latter, in its turn, leads to the highly localized loss of material, which is the reason why even closed cracks are visible by a naked eye. Thus, fracture can be interpreted as the local material sink. Mass conservation is violated locally in the area of material failure. We consider a theoretical formulation of the coupled mass and momenta balance equations for a description of fracture. Our focus is on brittle fracture and we propose a finite strain hyperelastic thermodynamic framework for the coupled mass-flow-elastic boundary value problem. The attractiveness of the proposed framework as compared to the traditional continuum damage theories is that no internal parameters (like damage variables, phase fields, etc.) are used while the regularization of the failure localization is provided by the physically sound law of mass balance.

  4. 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

  5. Traumatic thoracolumbar spine fractures

    NARCIS (Netherlands)

    J. Siebenga (Jan)

    2013-01-01

    textabstractTraumatic spinal fractures have the lowest functional outcomes and the lowest rates of return to work after injury of all major organ systems.1 This thesis will cover traumatic thoracolumbar spine fractures and not osteoporotic spine fractures because of the difference in fracture

  6. Fractures in multiple sclerosis

    DEFF Research Database (Denmark)

    Stenager, E; Jensen, K

    1991-01-01

    In a cross-sectional study of 299 MS patients 22 have had fractures and of these 17 after onset of MS. The fractures most frequently involved the femoral neck and trochanter (41%). Three patients had had more than one fracture. Only 1 patient had osteoporosis. The percentage of fractures increase...

  7. Risk factors for stress fractures.

    Science.gov (United States)

    Bennell, K; Matheson, G; Meeuwisse, W; Brukner, P

    1999-08-01

    Preventing stress fractures requires knowledge of the risk factors that predispose to this injury. The aetiology of stress fractures is multifactorial, but methodological limitations and expediency often lead to research study designs that evaluate individual risk factors. Intrinsic risk factors include mechanical factors such as bone density, skeletal alignment and body size and composition, physiological factors such as bone turnover rate, flexibility, and muscular strength and endurance, as well as hormonal and nutritional factors. Extrinsic risk factors include mechanical factors such as surface, footwear and external loading as well as physical training parameters. Psychological traits may also play a role in increasing stress fracture risk. Equally important to these types of analyses of individual risk factors is the integration of information to produce a composite picture of risk. The purpose of this paper is to critically appraise the existing literature by evaluating study design and quality, in order to provide a current synopsis of the known scientific information related to stress fracture risk factors. The literature is not fully complete with well conducted studies on this topic, but a great deal of information has accumulated over the past 20 years. Although stress fractures result from repeated loading, the exact contribution of training factors (volume, intensity, surface) has not been clearly established. From what we do know, menstrual disturbances, caloric restriction, lower bone density, muscle weakness and leg length differences are risk factors for stress fracture. Other time-honoured risk factors such as lower extremity alignment have not been shown to be causative even though anecdotal evidence indicates they are likely to play an important role in stress fracture pathogenesis.

  8. Assessment of fracture risk

    International Nuclear Information System (INIS)

    Kanis, John A.; Johansson, Helena; Oden, Anders; McCloskey, Eugene V.

    2009-01-01

    Fractures are a common complication of osteoporosis. Although osteoporosis is defined by bone mineral density at the femoral neck, other sites and validated techniques can be used for fracture prediction. Several clinical risk factors contribute to fracture risk independently of BMD. These include age, prior fragility fracture, smoking, excess alcohol, family history of hip fracture, rheumatoid arthritis and the use of oral glucocorticoids. These risk factors in conjunction with BMD can be integrated to provide estimates of fracture probability using the FRAX tool. Fracture probability rather than BMD alone can be used to fashion strategies for the assessment and treatment of osteoporosis.

  9. Clinical effects of internal fixation for ulnar styloid fractures associated with distal radius fractures: A matched case-control study.

    Science.gov (United States)

    Sawada, Hideyoshi; Shinohara, Takaaki; Natsume, Tadahiro; Hirata, Hitoshi

    2016-11-01

    Ulnar styloid fractures are often associated with distal radius fractures. However, controversy exists regarding whether to treat ulnar styloid fractures. This study aimed to evaluate clinical effects of internal fixation for ulnar styloid fractures after distal radius fractures were treated with the volar locking plate system. We used prospectively collected data of distal radius fractures. 111 patients were enrolled in this study. A matched case-control study design was used. We selected patients who underwent fixation for ulnar styloid fractures (case group). Three control patients for each patient of the case group were matched on the basis of age, sex, and fracture type of distal radius fractures from among patients who did not undergo fixation for ulnar styloid fractures (control group). The case group included 16 patients (7 men, 9 women; mean age: 52.6 years; classification of ulnar styloid fractures: center, 3; base, 11; and proximal, 2). The control group included 48 patients (15 men, 33 women; mean age: 61.1 years; classification of ulnar styloid fractures: center, 10; base, 31; and proximal, 7). For radiographic examination, the volar tilt angle, radial inclination angle, and ulnar variance length were measured, and the union of ulnar styloid fractures was judged. For clinical examination, the range of motions, grip strength, Hand20 score, and Numeric Rating Scale score were evaluated. There was little correction loss for each radiological parameter of fracture reduction, and these parameters were not significantly different between the groups. The bone-healing rate of ulnar styloid fractures was significantly higher in the case group than in the control group, but the clinical results were not significantly different. We revealed that there was no need to fix ulnar styloid fractures when distal radius fractures were treated via open reduction and internal fixation with a volar locking plate system. Copyright © 2016 The Japanese Orthopaedic Association

  10. Fracture modelling of a high performance armour steel

    Science.gov (United States)

    Skoglund, P.; Nilsson, M.; Tjernberg, A.

    2006-08-01

    The fracture characteristics of the high performance armour steel Armox 500T is investigated. Tensile mechanical experiments using samples with different notch geometries are used to investigate the effect of multi-axial stress states on the strain to fracture. The experiments are numerically simulated and from the simulation the stress at the point of fracture initiation is determined as a function of strain and these data are then used to extract parameters for fracture models. A fracture model based on quasi-static experiments is suggested and the model is tested against independent experiments done at both static and dynamic loading. The result show that the fracture model give reasonable good agreement between simulations and experiments at both static and dynamic loading condition. This indicates that multi-axial loading is more important to the strain to fracture than the deformation rate in the investigated loading range. However on-going work will further characterise the fracture behaviour of Armox 500T.

  11. Cohesive fracture model for functionally graded fiber reinforced concrete

    International Nuclear Information System (INIS)

    Park, Kyoungsoo; Paulino, Glaucio H.; Roesler, Jeffery

    2010-01-01

    A simple, effective, and practical constitutive model for cohesive fracture of fiber reinforced concrete is proposed by differentiating the aggregate bridging zone and the fiber bridging zone. The aggregate bridging zone is related to the total fracture energy of plain concrete, while the fiber bridging zone is associated with the difference between the total fracture energy of fiber reinforced concrete and the total fracture energy of plain concrete. The cohesive fracture model is defined by experimental fracture parameters, which are obtained through three-point bending and split tensile tests. As expected, the model describes fracture behavior of plain concrete beams. In addition, it predicts the fracture behavior of either fiber reinforced concrete beams or a combination of plain and fiber reinforced concrete functionally layered in a single beam specimen. The validated model is also applied to investigate continuously, functionally graded fiber reinforced concrete composites.

  12. Modelling of Local Necking and Fracture in Aluminium Alloys

    International Nuclear Information System (INIS)

    Achani, D.; Eriksson, M.; Hopperstad, O. S.; Lademo, O.-G.

    2007-01-01

    Non-linear Finite Element simulations are extensively used in forming and crashworthiness studies of automotive components and structures in which fracture need to be controlled. For thin-walled ductile materials, the fracture-related phenomena that must be properly represented are thinning instability, ductile fracture and through-thickness shear instability. Proper representation of the fracture process relies on the accuracy of constitutive and fracture models and their parameters that need to be calibrated through well defined experiments. The present study focuses on local necking and fracture which is of high industrial importance, and uses a phenomenological criterion for modelling fracture in aluminium alloys. As an accurate description of plastic anisotropy is important, advanced phenomenological constitutive equations based on the yield criterion YLD2000/YLD2003 are used. Uniaxial tensile tests and disc compression tests are performed for identification of the constitutive model parameters. Ductile fracture is described by the Cockcroft-Latham fracture criterion and an in-plane shear tests is performed to identify the fracture parameter. The reason is that in a well designed in-plane shear test no thinning instability should occur and it thus gives more direct information about the phenomenon of ductile fracture. Numerical simulations have been performed using a user-defined material model implemented in the general-purpose non-linear FE code LS-DYNA. The applicability of the model is demonstrated by correlating the predicted and experimental response in the in-plane shear tests and additional plane strain tension tests

  13. Dependence of fracture mechanical and fluid flow properties on fracture roughness and sample size

    International Nuclear Information System (INIS)

    Tsang, Y.W.; Witherspoon, P.A.

    1983-01-01

    A parameter study has been carried out to investigate the interdependence of mechanical and fluid flow properties of fractures with fracture roughness and sample size. A rough fracture can be defined mathematically in terms of its aperture density distribution. Correlations were found between the shapes of the aperture density distribution function and the specific fractures of the stress-strain behavior and fluid flow characteristics. Well-matched fractures had peaked aperture distributions that resulted in very nonlinear stress-strain behavior. With an increasing degree of mismatching between the top and bottom of a fracture, the aperture density distribution broadened and the nonlinearity of the stress-strain behavior became less accentuated. The different aperture density distributions also gave rise to qualitatively different fluid flow behavior. Findings from this investigation make it possible to estimate the stress-strain and fluid flow behavior when the roughness characteristics of the fracture are known and, conversely, to estimate the fracture roughness from an examination of the hydraulic and mechanical data. Results from this study showed that both the mechanical and hydraulic properties of the fracture are controlled by the large-scale roughness of the joint surface. This suggests that when the stress-flow behavior of a fracture is being investigated, the size of the rock sample should be larger than the typical wave length of the roughness undulations

  14. Fracturing process and effect of fracturing degree on wave velocity of a crystalline rock

    Directory of Open Access Journals (Sweden)

    Charalampos Saroglou

    2017-10-01

    Full Text Available The present paper investigates the effect of fracturing degree on P- and S-wave velocities in rock. The deformation of intact brittle rocks under loading conditions is characterized by a microcracking procedure, which occurs due to flaws in their microscopic structure and propagates through the intact rock, leading to shear fracture. This fracturing process is of fundamental significance as it affects the mechanical properties of the rock and hence the wave velocities. In order to determine the fracture mechanism and the effect of fracturing degree, samples were loaded at certain percentages of peak strength and ultrasonic wave velocity was recorded after every test. The fracturing degree was recorded on the outer surface of the sample and quantified by the use of the indices P10 (traces of joints/m, P20 (traces of joints/m2 and P21 (length of fractures/m2. It was concluded that the wave velocity decreases exponentially with increasing fracturing degree. Additionally, the fracturing degree is described adequately with the proposed indices. Finally, other parameters concerning the fracture characteristics, rock type and scale influence were found to contribute to the velocity decay and need to be investigated further.

  15. Multi-zone coupling productivity of horizontal well fracturing with complex fracture networks in shale gas reservoirs

    Directory of Open Access Journals (Sweden)

    Weiyao Zhu

    2018-02-01

    best. Therefore, it is necessary to control fracturing degree reasonably and optimize fracturing parameters, so as to provide a theoretical support for the optimization design of shale gas reservoir fracturing. Keywords: Shale gas, Reservoir, Fracturing, Horizontal well, Complex fracture network, Multi-zone coupling, Multi-scale, Interference, Productivity capacity

  16. Paratrooper's ankle fracture: posterior malleolar fracture.

    Science.gov (United States)

    Young, Ki Won; Kim, Jin-su; Cho, Jae Ho; Kim, Hyung Seuk; Cho, Hun Ki; Lee, Kyung Tai

    2015-03-01

    We assessed the frequency and types of ankle fractures that frequently occur during parachute landings of special operation unit personnel and analyzed the causes. Fifty-six members of the special force brigade of the military who had sustained ankle fractures during parachute landings between January 2005 and April 2010 were retrospectively analyzed. The injury sites and fracture sites were identified and the fracture types were categorized by the Lauge-Hansen and Weber classifications. Follow-up surveys were performed with respect to the American Orthopedic Foot and Ankle Society ankle-hindfoot score, patient satisfaction, and return to preinjury activity. The patients were all males with a mean age of 23.6 years. There were 28 right and 28 left ankle fractures. Twenty-two patients had simple fractures and 34 patients had comminuted fractures. The average number of injury and fractures sites per person was 2.07 (116 injuries including a syndesmosis injury and a deltoid injury) and 1.75 (98 fracture sites), respectively. Twenty-three cases (41.07%) were accompanied by posterior malleolar fractures. Fifty-five patients underwent surgery; of these, 30 had plate internal fixations. Weber type A, B, and C fractures were found in 4, 38, and 14 cases, respectively. Based on the Lauge-Hansen classification, supination-external rotation injuries were found in 20 cases, supination-adduction injuries in 22 cases, pronation-external rotation injuries in 11 cases, tibiofibular fractures in 2 cases, and simple medial malleolar fractures in 2 cases. The mean follow-up period was 23.8 months, and the average follow-up American Orthopedic Foot and Ankle Society ankle-hindfoot score was 85.42. Forty-five patients (80.36%) reported excellent or good satisfaction with the outcome. Posterior malleolar fractures occurred in 41.07% of ankle fractures sustained in parachute landings. Because most of the ankle fractures in parachute injuries were compound fractures, most cases had to

  17. Stress fractures in elite cross-country athletes.

    Science.gov (United States)

    Laker, Scott R; Saint-Phard, Deborah; Tyburski, Mark; Van Dorsten, Brent

    2007-04-01

    This retrospective and comparative survey investigates an unusual number of stress fractures seen within a Division I college cross-country team. An anonymous questionnaire-designed to observe factors known to increase stress fracture incidence-was distributed to members of the current and previous seasons' teams. Running surface, sleep hours, intake of calcium, and shoe type were among the factors investigated. Eleven lower extremity stress fractures were found in nine athletes. Athletes with stress fractures reported significantly fewer workouts per week on the new track. All other study parameters had no statistically significant effect on stress fractures in these athletes.

  18. Determination of vibrational parameters of methanol from matrix-isolation infrared spectroscopy and ab initio calculations. Part 1 - Spectral analysis in the domain 11 000-200 cm{sup -1}

    Energy Technology Data Exchange (ETDEWEB)

    Perchard, J.P. [Universite Pierre et Marie Curie, CNRS, Laboratoire de Dynamique, Interactions et Reactivite, UMR 7075, Case 49, 4 Place Jussieu, 75252 Paris (France)], E-mail: jpp@spmol.jussieu.fr; Romain, F. [Universite Pierre et Marie Curie, CNRS, Laboratoire de Dynamique, Interactions et Reactivite, UMR 7075, Case 49, 4 Place Jussieu, 75252 Paris (France); Bouteiller, Y. [Universite Paris-Nord, CNRS, Laboratoire de Physique des Lasers, UMR 7538, 93430 Villetaneuse (France)

    2008-01-22

    Infrared spectra of three isotopic species of methanol ({sup 12}CH{sub 3}{sup 16}OH, {sup 13}CH{sub 3}{sup 16}OH, {sup 12}CH{sub 3}{sup 18}OH) trapped in neon and nitrogen matrices have been recorded between 11 000 and 200 cm{sup -1}. Their analysis is based on the isotopic effects which slightly modify the frequencies without significantly changing the nature of vibrations nor the band intensities. From the assignment of most of the two quanta transitions 45 out of the 78 anharmonicity coefficients have been deduced. The value of some of them has been confirmed by the identification of three quanta transitions mainly involving the OH stretching mode. The problem of vibrational resonances between methyl bending and stretching modes has been tackled by performing complementary experiments: use of other isotopic species (CH{sub 3}OD, CH{sub 2}DOH) and acquisition of Raman spectra in the gas phase.

  19. 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.

  20. An XFEM Model for Hydraulic Fracturing in Partially Saturated Rocks

    Directory of Open Access Journals (Sweden)

    Salimzadeh Saeed

    2016-01-01

    Full Text Available Hydraulic fracturing is a complex multi-physics phenomenon. Numerous analytical and numerical models of hydraulic fracturing processes have been proposed. Analytical solutions commonly are able to model the growth of a single hydraulic fracture into an initially intact, homogeneous rock mass. Numerical models are able to analyse complex problems such as multiple hydraulic fractures and fracturing in heterogeneous media. However, majority of available models are restricted to single-phase flow through fracture and permeable porous rock. This is not compatible with actual field conditions where the injected fluid does not have similar properties as the host fluid. In this study we present a fully coupled hydro-poroelastic model which incorporates two fluids i.e. fracturing fluid and host fluid. Flow through fracture is defined based on lubrication assumption, while flow through matrix is defined as Darcy flow. The fracture discontinuity in the mechanical model is captured using eXtended Finite Element Method (XFEM while the fracture propagation criterion is defined through cohesive fracture model. The discontinuous matrix fluid velocity across fracture is modelled using leak-off loading which couples fracture flow and matrix flow. The proposed model has been discretised using standard Galerkin method, implemented in Matlab and verified against several published solutions. Multiple hydraulic fracturing simulations are performed to show the model robustness and to illustrate how problem parameters such as injection rate and rock permeability affect the hydraulic fracturing variables i.e. injection pressure, fracture aperture and fracture length. The results show the impact of partial saturation on leak-off and the fact that single-phase models may underestimate the leak-off.

  1. Is human fracture hematoma inherently angiogenic?

    LENUS (Irish Health Repository)

    Street, J

    2012-02-03

    This study attempts to explain the cellular events characterizing the changes seen in the medullary callus adjacent to the interfragmentary hematoma during the early stages of fracture healing. It also shows that human fracture hematoma contains the angiogenic cytokine vascular endothelial growth factor and has the inherent capability to induce angiogenesis and thus promote revascularization during bone repair. Patients undergoing emergency surgery for isolated bony injury were studied. Raised circulating levels of vascular endothelial growth factor were seen in all injured patients, whereas the fracture hematoma contained significantly higher levels of vascular endothelial growth factor than did plasma from these injured patients. However, incubation of endothelial cells in fracture hematoma supernatant significantly inhibited the in vitro angiogenic parameters of endothelial cell proliferation and microtubule formation. These phenomena are dependent on a local biochemical milieu that does not support cytokinesis. The hematoma potassium concentration is cytotoxic to endothelial cells and osteoblasts. Subcutaneous transplantation of the fracture hematoma into a murine wound model resulted in new blood vessel formation after hematoma resorption. This angiogenic effect is mediated by the significant concentrations of vascular endothelial growth factor found in the hematoma. This study identifies an angiogenic cytokine involved in human fracture healing and shows that fracture hematoma is inherently angiogenic. The differences between the in vitro and in vivo findings may explain the phenomenon of interfragmentary hematoma organization and resorption that precedes fracture revascularization.

  2. 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.)

  3. Two-criteria method for fracture-mechanical analysis of pipelines - practical application and influencing parameters; Zwei-Kriterien-Verfahren zur bruchmechanischen Befundbewertung in Rohrleitungen - praktische Anwendung und Einflussgroessen

    Energy Technology Data Exchange (ETDEWEB)

    Beukelmann, D. [TUeV Sued Industrie Service GmbH (Germany); Doerk, O.; Wernicke, R. [TUeV Nord SysTec GmbH und Co. KG (Germany)

    2006-07-01

    The findings obtained in recurrent inspections as a rule are evaluated by fracture-mechanical analyses. On the basis of the results, it is decided whether a component must be repaired or if operation can continue as it is for the time being. The two-criteria method is applied as a rule because of its universal applicability. Limited ductile crack growth can be taken into account if crack resistance curves are available that can be transferred to the component in question. In the investigations presented here, the influence of the relevant initial variables, e.g. strength coefficents, fracture-mechanical material coefficients, primary and secondary stresses and the intrinsic state of stress is illustrated by exemplary calculations. Further, the safety concepts underlying the assessment are gone into. (orig.)

  4. Probabilistic fracture finite elements

    Science.gov (United States)

    Liu, W. K.; Belytschko, T.; Lua, Y. J.

    1991-05-01

    The Probabilistic Fracture Mechanics (PFM) is a promising method for estimating the fatigue life and inspection cycles for mechanical and structural components. The Probability Finite Element Method (PFEM), which is based on second moment analysis, has proved to be a promising, practical approach to handle problems with uncertainties. As the PFEM provides a powerful computational tool to determine first and second moment of random parameters, the second moment reliability method can be easily combined with PFEM to obtain measures of the reliability of the structural system. The method is also being applied to fatigue crack growth. Uncertainties in the material properties of advanced materials such as polycrystalline alloys, ceramics, and composites are commonly observed from experimental tests. This is mainly attributed to intrinsic microcracks, which are randomly distributed as a result of the applied load and the residual stress.

  5. Fractures (Broken Bones): First Aid

    Science.gov (United States)

    First aid Fractures (broken bones) Fractures (broken bones): First aid By Mayo Clinic Staff A fracture is a ... 10, 2018 Original article: http://www.mayoclinic.org/first-aid/first-aid-fractures/basics/ART-20056641 . Mayo Clinic ...

  6. Estimation of Fracture Porosity in an Unsaturated Fractured Welded Tuff Using Gas Tracer Testing

    Energy Technology Data Exchange (ETDEWEB)

    B.M. Freifeild

    2001-10-18

    Kinematic fracture porosity is an important hydrologic transport parameter for predicting the potential of rapid contaminant migration through fractured rock. The transport velocity of a solute moving within a fracture network is inversely related to the fracture porosity. Since fracture porosity is often one or two orders of magnitude smaller than matrix porosity, and fracture permeability is often orders of magnitude greater than matrix permeability, solutes may travel significantly faster in the fracture network than in the surrounding matrix. This dissertation introduces a new methodology for conducting gas tracer tests using a field portable mass spectrometer along with analytical tools for estimating fracture porosity using the measured tracer concentration breakthrough curves. Field experiments were conducted at Yucca Mountain, Nevada, consisting of air-permeability transient testing and gas-tracer-transport tests. The experiments were conducted from boreholes drilled within an underground tunnel as part of an investigation of rock mass hydrological behavior. Air-permeability pressure transients, recorded during constant mass flux injections, have been analyzed using a numerical inversion procedure to identify fracture permeability and porosity. Dipole gas tracer tests have also been conducted from the same boreholes used for air-permeability testing. Mass breakthrough data has been analyzed using a random walk particle-tracking model, with a dispersivity that is a function of the advective velocity. The estimated fracture porosity using the tracer test and air-injection test data ranges from .001 to .015. These values are an order of magnitude greater than the values estimated by others using hydraulically estimated fracture apertures. The estimates of porosity made using air-permeability test data are shown to be highly sensitive to formation heterogeneity. Uncertainty analyses performed on the gas tracer test results show high confidence in the parameter

  7. Estimation of fracture porosity in an unsaturated fractured welded tuff using gas tracer testing

    Energy Technology Data Exchange (ETDEWEB)

    Freifeld, Barry Mark [Univ. of California, Berkeley, CA (United States)

    2001-12-01

    Kinematic fracture porosity is an important hydrologic transport parameter for predicting the potential of rapid contaminant migration through fractured rock. The transport velocity of a solute moving within a fracture network is inversely related to the fracture porosity. Since fracture porosity is often one or two orders of magnitude smaller than matrix porosity, and fracture permeability is often orders of magnitude greater than matrix permeability, solutes may travel significantly faster in the fracture network than in the surrounding matrix. This dissertation introduces a new methodology for conducting gas tracer tests using a field portable mass spectrometer along with analytical tools for estimating fracture porosity using the measured tracer concentration breakthrough curves. Field experiments were conducted at Yucca Mountain, Nevada, consisting of air-permeability transient testing and gas-tracer-transport tests. The experiments were conducted from boreholes drilled within an underground tunnel as part of an investigation of rock mass hydrological behavior. Air-permeability pressure transients, recorded during constant mass flux injections, have been analyzed using a numerical inversion procedure to identify fracture permeability and porosity. Dipole gas tracer tests have also been conducted from the same boreholes used for air-permeability testing. Mass breakthrough data has been analyzed using a random walk particle-tracking model, with a dispersivity that is a function of the advective velocity. The estimated fracture porosity using the tracer test and air-injection test data ranges from .001 to .015. These values are an order of magnitude greater than the values estimated by others using hydraulically estimated fracture apertures. The estimates of porosity made using air-permeability test data are shown to be highly sensitive to formation heterogeneity. Uncertainty analyses performed on the gas tracer test results show high confidence in the parameter

  8. Estimation of Fracture Porosity in an Unsaturated Fractured Welded Tuff Using Gas Tracer Testing

    International Nuclear Information System (INIS)

    B.M. Freifeild

    2001-01-01

    Kinematic fracture porosity is an important hydrologic transport parameter for predicting the potential of rapid contaminant migration through fractured rock. The transport velocity of a solute moving within a fracture network is inversely related to the fracture porosity. Since fracture porosity is often one or two orders of magnitude smaller than matrix porosity, and fracture permeability is often orders of magnitude greater than matrix permeability, solutes may travel significantly faster in the fracture network than in the surrounding matrix. This dissertation introduces a new methodology for conducting gas tracer tests using a field portable mass spectrometer along with analytical tools for estimating fracture porosity using the measured tracer concentration breakthrough curves. Field experiments were conducted at Yucca Mountain, Nevada, consisting of air-permeability transient testing and gas-tracer-transport tests. The experiments were conducted from boreholes drilled within an underground tunnel as part of an investigation of rock mass hydrological behavior. Air-permeability pressure transients, recorded during constant mass flux injections, have been analyzed using a numerical inversion procedure to identify fracture permeability and porosity. Dipole gas tracer tests have also been conducted from the same boreholes used for air-permeability testing. Mass breakthrough data has been analyzed using a random walk particle-tracking model, with a dispersivity that is a function of the advective velocity. The estimated fracture porosity using the tracer test and air-injection test data ranges from .001 to .015. These values are an order of magnitude greater than the values estimated by others using hydraulically estimated fracture apertures. The estimates of porosity made using air-permeability test data are shown to be highly sensitive to formation heterogeneity. Uncertainty analyses performed on the gas tracer test results show high confidence in the parameter

  9. Rib fracture - aftercare

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000539.htm Rib fracture - aftercare To use the sharing features on this page, please enable JavaScript. A rib fracture is a crack or break in one or ...

  10. Sprains, Strains and Fractures

    Science.gov (United States)

    ... fractures. Many fractures and sprains occur during sports. Football players are particularly vulnerable to foot and ankle ... feet and ankles and take a complete medical history. He or she will also order tests, including ...

  11. Infant skull fracture (image)

    Science.gov (United States)

    Skull fractures may occur with head injuries. Although the skull is both tough and resilient and provides excellent ... or blow can result in fracture of the skull and may be accompanied by injury to the ...

  12. Ankle fracture - aftercare

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000548.htm Ankle fracture - aftercare To use the sharing features on this page, please enable JavaScript. An ankle fracture is a break in 1 or more ankle ...

  13. Atraumatic First Rib Fracture

    OpenAIRE

    Koray Aydogdu

    2014-01-01

    Rib fractures are usually seen after a trauma, while atraumatic spontaneous rib fractures are quite rare. A first rib fracture identified in our 17 years old female patient who had not a history of trauma except lifting a heavy weight was examined in details in terms of the potential complications and followed-up for a long time. We presented our experience on this case with atraumatic first rib fracture that has different views for the etiology in light of the literature.

  14. Metatarsal stress fractures - aftercare

    Science.gov (United States)

    ... Metatarsal stress fracture. In: Safran MR, Zachazewski J, Stone DA, eds. Instructions for Sports Medicine Patients . 2nd ed. Elsevier Saunders; 2012:648-652. Smith MS. Metatarsal fractures. In: Eiff PM, Hatch R, eds. Fracture Management for Primary Care . 3rd ed. ...

  15. Relationships between fractures

    Science.gov (United States)

    Peacock, D. C. P.; Sanderson, D. J.; Rotevatn, A.

    2018-01-01

    Fracture systems comprise many fractures that may be grouped into sets based on their orientation, type and relative age. The fractures are often arranged in a network that involves fracture branches that interact with one another. Interacting fractures are termed geometrically coupled when they share an intersection line and/or kinematically coupled when the displacements, stresses and strains of one fracture influences those of the other. Fracture interactions are characterised in terms of the following. 1) Fracture type: for example, whether they have opening (e.g., joints, veins, dykes), closing (stylolites, compaction bands), shearing (e.g., faults, deformation bands) or mixed-mode displacements. 2) Geometry (e.g., relative orientations) and topology (the arrangement of the fractures, including their connectivity). 3) Chronology: the relative ages of the fractures. 4) Kinematics: the displacement distributions of the interacting fractures. It is also suggested that interaction can be characterised in terms of mechanics, e.g., the effects of the interaction on the stress field. It is insufficient to describe only the components of a fracture network, with fuller understanding coming from determining the interactions between the different components of the network.

  16. Obesity and fracture risk

    OpenAIRE

    Gonnelli, Stefano; Caffarelli, Carla; Nuti, Ranuccio

    2014-01-01

    Obesity and osteoporosis are two common diseases with an increasing prevalence and a high impact on morbidity and mortality. Obese women have always been considered protected against osteoporosis and osteoporotic fractures. However, several recent studies have challenged the widespread belief that obesity is protective against fracture and have suggested that obesity is a risk factor for certain fractures.

  17. Imaging of insufficiency fractures

    Energy Technology Data Exchange (ETDEWEB)

    Krestan, Christian [Department of Radiology, Medical University of Vienna, Vienna General Hospital, Waehringerstr. 18-20, 1090 Vienna (Austria)], E-mail: christian.krestan@meduniwien.ac.at; Hojreh, Azadeh [Department of Radiology, Medical University of Vienna, Vienna General Hospital, Waehringerstr. 18-20, 1090 Vienna (Austria)

    2009-09-15

    This review focuses on the occurrence, imaging and differential diagnosis of insufficiency fractures. Prevalence, the most common sites of insufficiency fractures and their clinical implications are discussed. Insufficiency fractures occur with normal stress exerted on weakened bone. Postmenopausal osteoporosis is the most common cause of insufficiency fractures. Other conditions which affect bone turnover include osteomalacia, hyperparathyroidism, chronic renal failure and high-dose glucocorticoid therapy. It is a challenge for the radiologist to detect and diagnose insufficiency fractures, and to differentiate them from other bone lesions. Radiographs are still the most widely used imaging method for identification of insufficiency fractures, but sensitivity is limited, depending on the location of the fractures. Magnetic resonance imaging (MRI) is a very sensitive tool to visualize bone marrow abnormalities associated with insufficiency fractures. Thin section, multi-detector computed tomography (MDCT) depicts subtle fracture lines allowing direct visualization of cortical and trabecular bone. Bone scintigraphy still plays a role in detecting fractures, with good sensitivity but limited specificity. The most important differential diagnosis is underlying malignant disease leading to pathologic fractures. Bone densitometry and clinical history may also be helpful in confirming the diagnosis of insufficiency fractures.

  18. Effect of Random Natural Fractures on Hydraulic Fracture Propagation Geometry in Fractured Carbonate Rocks

    Science.gov (United States)

    Liu, Zhiyuan; Wang, Shijie; Zhao, Haiyang; Wang, Lei; Li, Wei; Geng, Yudi; Tao, Shan; Zhang, Guangqing; Chen, Mian

    2018-02-01

    Natural fractures have a significant influence on the propagation geometry of hydraulic fractures in fractured reservoirs. True triaxial volumetric fracturing experiments, in which random natural fractures are created by placing cement blocks of different dimensions in a cuboid mold and filling the mold with additional cement to create the final test specimen, were used to study the factors that influence the hydraulic fracture propagation geometry. These factors include the presence of natural fractures around the wellbore, the dimension and volumetric density of random natural fractures and the horizontal differential stress. The results show that volumetric fractures preferentially formed when natural fractures occurred around the wellbore, the natural fractures are medium to long and have a volumetric density of 6-9%, and the stress difference is less than 11 MPa. The volumetric fracture geometries are mainly major multi-branch fractures with fracture networks or major multi-branch fractures (2-4 fractures). The angles between the major fractures and the maximum horizontal in situ stress are 30°-45°, and fracture networks are located at the intersections of major multi-branch fractures. Short natural fractures rarely led to the formation of fracture networks. Thus, the interaction between hydraulic fractures and short natural fractures has little engineering significance. The conclusions are important for field applications and for gaining a deeper understanding of the formation process of volumetric fractures.

  19. Role of MRI in hip fractures, including stress fractures, occult fractures, avulsion fractures

    International Nuclear Information System (INIS)

    Nachtrab, O.; Cassar-Pullicino, V.N.; Lalam, R.; Tins, B.; Tyrrell, P.N.M.; Singh, J.

    2012-01-01

    MR imaging plays a vital role in the diagnosis and management of hip fractures in all age groups, in a large spectrum of patient groups spanning the elderly and sporting population. It allows a confident exclusion of fracture, differentiation of bony from soft tissue injury and an early confident detection of fractures. There is a spectrum of MR findings which in part is dictated by the type and cause of the fracture which the radiologist needs to be familiar with. Judicious but prompt utilisation of MR in patients with suspected hip fractures has a positive therapeutic impact with healthcare cost benefits as well as social care benefits.

  20. Fracture toughness testing of a reactor grade graphite

    Energy Technology Data Exchange (ETDEWEB)

    Roeding, M.; Klein, G.; Schiffers, H.; Nickel, H.

    1976-03-15

    Fracture mechanics is a well established tool for the assessment of brittle fracture in metallic structural materials. In this paper an attempt is made to apply fracture mechanics to a reactor-grade graphite. The effect of several test parameters on the stress intensity factor was measured; this was found to lie in the range 25 and 50 N/mm/sup -3/2/. The results are discussed in terms of the well known mechanical characteristics of graphite.

  1. Orbital fractures: a review

    Directory of Open Access Journals (Sweden)

    Jeffrey M Joseph

    2011-01-01

    Full Text Available Jeffrey M Joseph, Ioannis P GlavasDivision of Ophthalmic Plastic and Reconstructive Surgery, Department of Ophthalmology, School of Medicine, New York University, New York, NY, USA; Manhattan Eye, Ear, and Throat Hospital, New York, NY, USAAbstract: This review of orbital fractures has three goals: 1 to understand the clinically relevant orbital anatomy with regard to periorbital trauma and orbital fractures, 2 to explain how to assess and examine a patient after periorbital trauma, and 3 to understand the medical and surgical management of orbital fractures. The article aims to summarize the evaluation and management of commonly encountered orbital fractures from the ophthalmologic perspective and to provide an overview for all practicing ophthalmologists and ophthalmologists in training.Keywords: orbit, trauma, fracture, orbital floor, medial wall, zygomatic, zygomatic complex, zmc fracture, zygomaticomaxillary complex fractures 

  2. Mechanics of Hydraulic Fractures

    Science.gov (United States)

    Detournay, Emmanuel

    2016-01-01

    Hydraulic fractures represent a particular class of tensile fractures that propagate in solid media under pre-existing compressive stresses as a result of internal pressurization by an injected viscous fluid. The main application of engineered hydraulic fractures is the stimulation of oil and gas wells to increase production. Several physical processes affect the propagation of these fractures, including the flow of viscous fluid, creation of solid surfaces, and leak-off of fracturing fluid. The interplay and the competition between these processes lead to multiple length scales and timescales in the system, which reveal the shifting influence of the far-field stress, viscous dissipation, fracture energy, and leak-off as the fracture propagates.

  3. Fracture in Soft Materials

    DEFF Research Database (Denmark)

    Hassager, Ole

    Fracture is a phenomenon that is generally associated with solids. A key element in fracture theory is the so-called weakest link idea that fracture initiates from the largest pre-existing material imperfection. However, recent work has demonstrated that fracture can also happen in liquids, where...... surface tension will act to suppress such imperfections. Therefore, the weakest link idea does not seem immediately applicable to fracture in liquids. This presentation will review fracture in liquids and argue that fracture in soft liquids is a material property independent of pre-existing imperfections....... The following questions then emerge: What is the material description needed to predict crack initiation, crack speed and crack shape in soft materials and liquids....

  4. 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

  5. Fracture heuristics: surgical decision for approaches to distal radius fractures. A surgeon's perspective.

    Science.gov (United States)

    Wichlas, Florian; Tsitsilonis, Serafim; Kopf, Sebastian; Krapohl, Björn Dirk; Manegold, Sebastian

    2017-01-01

    Introduction: The aim of the present study is to develop a heuristic that could replace the surgeon's analysis for the decision on the operative approach of distal radius fractures based on simple fracture characteristics. Patients and methods: Five hundred distal radius fractures operated between 2011 and 2014 were analyzed for the surgeon's decision on the approach used. The 500 distal radius fractures were treated with open reduction and internal fixation through palmar, dorsal, and dorsopalmar approaches with 2.4 mm locking plates or underwent percutaneous fixation. The parameters that should replace the surgeon's analysis were the fractured palmar cortex, and the frontal and the sagittal split of the articular surface of the distal radius. Results: The palmar approach was used for 422 (84.4%) fractures, the dorsal approach for 39 (7.8%), and the combined dorsopalmar approach for 30 (6.0%). Nine (1.8%) fractures were treated percutaneously. The correlation between the fractured palmar cortex and the used palmar approach was moderate (r=0.464; p<0.0001). The correlation between the frontal split and the dorsal approach, including the dorsopalmar approach, was strong (r=0.715; p<0.0001). The sagittal split had only a weak correlation for the dorsal and dorsopalmar approach (r=0.300; p<0.0001). Discussion: The study shows that the surgical decision on the preferred approach is dictated through two simple factors, even in the case of complex fractures. Conclusion: When the palmar cortex is displaced in distal radius fractures, a palmar approach should be used. When there is a displaced frontal split of the articular surface, a dorsal approach should be used. When both are present, a dorsopalmar approach should be used. These two simple parameters could replace the surgeon's analysis for the surgical approach.

  6. An interim report on shallow-flaw fracture technology development

    International Nuclear Information System (INIS)

    Pennell, W.E.; Bass, B.R.; Bryson, J.W.; McAfee, W.J.

    1995-01-01

    Shallow-flaw fracture technology is being developed for application to the safety assessment of radiation-embrittled nuclear reactor pressure vessels (RPVS) containing flaws. Fracture mechanics tests on RPV steel, coupled with detailed elastic-plastic finite-element analyses of the crack-tip stress fields, have shown that (1) constraint relaxation at the crack tip of shallow surface flaws results in increased data scatter but no increase in the lower-bound fracture toughness, (2) the nil ductility temperature (NDT) performs better than the reference temperature for nil ductility transition (RT NDT ) as a normalizing parameter for shallow-flaw fracture toughness data, (3) biaxial loading can reduce the shallow-flaw fracture toughness, (4) stress-based dual-parameter fracture toughness correlations cannot predict the effect of biaxial loading on shallow-flaw fracture toughness because in-plane stresses at the crack tip are not influenced by biaxial loading, and (5) a strain-based dual-parameter fracture toughness correlation can predict the effect of biaxial loading on shallow-flaw fracture toughness

  7. A new algorithm for hip fracture surgery

    DEFF Research Database (Denmark)

    Palm, Henrik; Krasheninnikoff, Michael; Holck, Kim

    2012-01-01

    Background and purpose Treatment of hip fracture patients is controversial. We implemented a new operative and supervision algorithm (the Hvidovre algorithm) for surgical treatment of all hip fractures, primarily based on own previously published results. Methods 2,000 consecutive patients over 50...... years of age who were admitted and operated on because of a hip fracture were prospectively included. 1,000 of these patients were included after implementation of the algorithm. Demographic parameters, hospital treatment, and reoperations within the first postoperative year were assessed from patient...... by reoperations was reduced from 24% of total hospitalization before the algorithm was introduced to 18% after it was introduced. Interpretation It is possible to implement an algorithm for treatment of all hip fracture patients in a large teaching hospital. In our case, the Hvidovre algorithm both raised...

  8. Pediatric femur fractures, epidemiology and treatment

    Directory of Open Access Journals (Sweden)

    Petković Lazar

    2011-01-01

    Full Text Available Background/Aim. Femur fractures in children most often occur as a consequence of traffic accidents, during play and sport activities, and due to different pathological states. Diagnosis is rather simple and it includes physical and radiographycal examination. Femur fractures treatment in children can be operative and unoperative, depending on several facts: age, localisation and type of fracture, joint injuries of soft tissues, the presence of other injuries (in polytrauma, economical and social aspects, ect. The aim of this study was to present epidemiological characteristics of pediatric femur fractures, that is in the stage of development, including a special analysis of the used treatment techniques, as well as the comparison of the obtained data with those from the literature. Methods. The evaluation included following parameters: age, gender, cause, localisation and type of femur fracture, applied treatment and hospitalisation duration. Results. Among the presented 143 patients with femur fracture, 109 were boys and 34 were girls (3.2 : 1 ratio; p = 0.0001. Average age for both genders was 8.6 years, and no difference between boys and girls were found for the age (p = 0.758. In total, the most common fracture was diaphyseal fracture of femur in 93 (65.03% patients. The second was proximal fracture in 30 (20.98% patients, and the last distal fracture of the femur in 20 (13.99% patients (p = 0.0001. Three main causes of femur fracture can be distinguished: during play and sport activities in 67 (46.8% children, in traffic accidents in 64 (44.8% children, and pathological fractures in 12 (8.4% children. Inoperative treatment was applied in 82 (57.3% patients, and operative one in 61 (42.7% patients. The most common tretament was traction, in 71 (49.6% patients, followed by immobilization by hip spica cast mostly in young children. Intramedullar elastic nailing was applied in 16 (11.2% cases, and intramedullar rigid nailing (Küntscher in 19

  9. Assessment of fracture toughness of structural steels

    Energy Technology Data Exchange (ETDEWEB)

    Gomes Junyor, José Onésimo; Faria, Stéfanno Bruno; Rocha, Nirlando Antônio; Reis, Emil; Vilela, Jefferson José, E-mail: ze_onezo@hotmail.com, E-mail: sbrunofaria@gmail.com, E-mail: nar@cdtn.br, E-mail: emilr@cdtn.br, E-mail: jjv@cdtn.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Centro Universitário de Belo Horizonte (UNIBH), MG (Brazil); Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2017-11-01

    The fracture toughness parameters are applied to estimate the lifetime of mechanical components and define the criteria of safe failure and tolerable damages. This information allows equipment to be used longer with a high degree of safety. These techniques are applied in the Leak-Before-Break (LBB) concept that is accepted for designing the piping system of the primary circuit of the pressurized water reactor (PWR). In this work, fracture toughness tests such as J{sub IC} and CTOD were performed on some structural steels. The fracture toughness parameters were determined using SE(B) and C(T) test specimens. The fracture toughness values for the same material varied according to the type specimen. The parameter δ{sub 1c} showed different values when it was calculated using the ASTM E1820 standard and using the BS 7448: Part 1 standard. These results indicate that procedures of these standards need to be improved. Two systems with different sensitivity in the force measurement were used that showed similar results for toughness fracture but the dispersion was different. (author)

  10. Ballistic fractures: indirect fracture to bone.

    Science.gov (United States)

    Dougherty, Paul J; Sherman, Don; Dau, Nathan; Bir, Cynthia

    2011-11-01

    Two mechanisms of injury, the temporary cavity and the sonic wave, have been proposed to produce indirect fractures as a projectile passes nearby in tissue. The purpose of this study is to evaluate the temporal relationship of pressure waves using strain gauge technology and high-speed video to elucidate whether the sonic wave, the temporary cavity, or both are responsible for the formation of indirect fractures. Twenty-eight fresh frozen cadaveric diaphyseal tibia (2) and femurs (26) were implanted into ordnance gelatin blocks. Shots were fired using 9- and 5.56-mm bullets traversing through the gelatin only, passing close to the edge of the bone, but not touching, to produce an indirect fracture. High-speed video of the impact event was collected at 20,000 frames/s. Acquisition of the strain data were synchronized with the video at 20,000 Hz. The exact time of fracture was determined by analyzing and comparing the strain gauge output and video. Twenty-eight shots were fired, 2 with 9-mm bullets and 26 with 5.56-mm bullets. Eight indirect fractures that occurred were of a simple (oblique or wedge) pattern. Comparison of the average distance of the projectile from the bone was 9.68 mm (range, 3-20 mm) for fractured specimens and 15.15 mm (range, 7-28 mm) for nonfractured specimens (Student's t test, p = 0.036). In this study, indirect fractures were produced after passage of the projectile. Thus, the temporary cavity, not the sonic wave, was responsible for the indirect fractures.

  11. Mechanical dispersion in fractured crystalline rock systems

    International Nuclear Information System (INIS)

    Lafleur, D.W.; Raven, K.G.

    1986-12-01

    This report compiles and evaluates the hydrogeologic parameters describing the flow of groundwater and transport of solutes in fractured crystalline rocks. This report describes the processes of mechanical dispersion in fractured crystalline rocks, and compiles and evaluates the dispersion parameters determined from both laboratory and field tracer experiments. The compiled data show that extrapolation of the reliable test results performed over intermediate scales (10's of m and 10's to 100's of hours) to larger spatial and temporal scales required for performance assessment of a nuclear waste repository in crystalline rock is not justified. The reliable measures of longitudinal dispersivity of fractured crystalline rock are found to range between 0.4 and 7.8 m

  12. On fracture in finite strain gradient plasticity

    DEFF Research Database (Denmark)

    Martínez Pañeda, Emilio; Niordson, Christian Frithiof

    2016-01-01

    In this work a general framework for damage and fracture assessment including the effect of strain gradients is provided. Both mechanism-based and phenomenological strain gradient plasticity (SGP) theories are implemented numerically using finite deformation theory and crack tip fields are invest......In this work a general framework for damage and fracture assessment including the effect of strain gradients is provided. Both mechanism-based and phenomenological strain gradient plasticity (SGP) theories are implemented numerically using finite deformation theory and crack tip fields...... are investigated. Differences and similarities between the two approaches within continuum SGP modeling are highlighted and discussed. Local strain hardening promoted by geometrically necessary dislocations (GNDs) in the vicinity of the crack leads to much higher stresses, relative to classical plasticity...... in the multiple parameter version of the phenomenological SGP theory. Since this also dominates the mechanics of indentation testing, results suggest that length parameters characteristic of mode I fracture should be inferred from nanoindentation....

  13. Representative elements: A step to large-scale fracture system simulation

    International Nuclear Information System (INIS)

    Clemo, T.M.

    1987-01-01

    Large-scale simulation of flow and transport in fractured media requires the development of a technique to represent the effect of a large number of fractures. Representative elements are used as a tool to model a subset of a fracture system as a single distributed entity. Representative elements are part of a modeling concept called dual permeability. Dual permeability modeling combines discrete fracture simulation of the most important fractures with the distributed modeling of the less important fracture of a fracture system. This study investigates the use of stochastic analysis to determine properties of representative elements. Given an assumption of fully developed laminar flow, the net fracture conductivities and hence flow velocities can be determined from descriptive statistics of fracture spacing, orientation, aperture, and extent. The distribution of physical characteristics about their mean leads to a distribution of the associated conductivities. The variance of hydraulic conductivity induces dispersion into the transport process. Simple fracture systems are treated to demonstrate the usefulness of stochastic analysis. Explicit equations for conductivity of an element are developed and the dispersion characteristics are shown. Explicit formulation of the hydraulic conductivity and transport dispersion reveals the dependence of these important characteristics on the parameters used to describe the fracture system. Understanding these dependencies will help to focus efforts to identify the characteristics of fracture systems. Simulations of stochastically generated fracture sets do not provide this explicit functional dependence on the fracture system parameters. 12 refs., 6 figs

  14. Fracture Characterization in Reactive Fluid-Fractured Rock Systems Using Tracer Transport Data

    Science.gov (United States)

    Mukhopadhyay, S.

    2014-12-01

    Fractures, whether natural or engineered, exert significant controls over resource exploitation from contemporary energy sources including enhanced geothermal systems and unconventional oil and gas reserves. Consequently, fracture characterization, i.e., estimating the permeability, connectivity, and spacing of the fractures is of critical importance for determining the viability of any energy recovery program. While some progress has recently been made towards estimating these critical fracture parameters, significant uncertainties still remain. A review of tracer technology, which has a long history in fracture characterization, reveals that uncertainties exist in the estimated parameters not only because of paucity of scale-specific data but also because of knowledge gaps in the interpretation methods, particularly in interpretation of tracer data in reactive fluid-rock systems. We have recently demonstrated that the transient tracer evolution signatures in reactive fluid-rock systems are significantly different from those in non-reactive systems (Mukhopadhyay et al., 2013, 2014). For example, the tracer breakthrough curves in reactive fluid-fractured rock systems are expected to exhibit a long pseudo-state condition, during which tracer concentration does not change by any appreciable amount with passage of time. Such a pseudo-steady state condition is not observed in a non-reactive system. In this paper, we show that the presence of this pseudo-steady state condition in tracer breakthrough patterns in reactive fluid-rock systems can have important connotations for fracture characterization. We show that the time of onset of the pseudo-steady state condition and the value of tracer concentration in the pseudo-state condition can be used to reliably estimate fracture spacing and fracture-matrix interface areas.

  15. Review of fracture properties of nuclear materials determined by Hertzian indentation

    International Nuclear Information System (INIS)

    Routbort, J.; Matzke, H.

    1985-01-01

    A brief description of the determination of the surface fracture energy and the fracture toughness from a Hertzian indentation test is given. A number of theoretical and experimental problems are discussed. Results obtained on a variety of nuclear fuels and nuclear-waste-containment materials are reviewed and compared with values measured by other techniques. The Hertzian indentation test yields reliable fracture parameters

  16. Atraumatic First Rib Fracture

    Directory of Open Access Journals (Sweden)

    Koray Aydogdu

    2014-12-01

    Full Text Available Rib fractures are usually seen after a trauma, while atraumatic spontaneous rib fractures are quite rare. A first rib fracture identified in our 17 years old female patient who had not a history of trauma except lifting a heavy weight was examined in details in terms of the potential complications and followed-up for a long time. We presented our experience on this case with atraumatic first rib fracture that has different views for the etiology in light of the literature.

  17. Scaphoid fractures in children

    Directory of Open Access Journals (Sweden)

    Gajdobranski Đorđe

    2014-01-01

    Full Text Available Introduction. Scaphoid fractures are rare in childhood. Diagnosis is very difficult to establish because carpal bones are not fully ossified. In suspected cases comparative or delayed radiography is used, as well as computerized tomography, magnetic resonance imaging, ultrasound and bone scintigraphy. Majority of scaphoid fractures are treated conservatively with good results. In case of delayed fracture healing various types of treatment are available. Objective. To determine the mechanism of injury, clinical healing process, types and outcome of treatment of scaphoid fractures in children. Methods. We retrospectively analyzed patients with traumatic closed fracture of the scaphoid bone over a ten-year period (2002-2011. The outcome of the treatment of “acute” scaphoid fracture was evaluated using the Mayo Wrist Score. Results. There were in total 34 patients, of mean age 13.8 years, with traumatic closed fracture of the scaphoid bone, whose bone growth was not finished yet. Most common injury mechanism was fall on outstretched arm - 76% of patients. During the examined period 31 children with “acute” fracture underwent conservative treatment, with average immobilization period of 51 days. Six patients were lost to follow-up. In the remaining 25 patients, after completed rehabilitation, functional results determined by the Mayo Wrist Score were excellent. Conclusion. Conservative therapy of “acute” scaphoid fractures is an acceptable treatment option for pediatric patients with excellent functional results.

  18. Pathological fractures in children

    Science.gov (United States)

    De Mattos, C. B. R.; Binitie, O.; Dormans, J. P.

    2012-01-01

    Pathological fractures in children can occur as a result of a variety of conditions, ranging from metabolic diseases and infection to tumours. Fractures through benign and malignant bone tumours should be recognised and managed appropriately by the treating orthopaedic surgeon. The most common benign bone tumours that cause pathological fractures in children are unicameral bone cysts, aneurysmal bone cysts, non-ossifying fibromas and fibrous dysplasia. Although pathological fractures through a primary bone malignancy are rare, these should be recognised quickly in order to achieve better outcomes. A thorough history, physical examination and review of plain radiographs are crucial to determine the cause and guide treatment. In most benign cases the fracture will heal and the lesion can be addressed at the time of the fracture, or after the fracture is healed. A step-wise and multidisciplinary approach is necessary in caring for paediatric patients with malignancies. Pathological fractures do not have to be treated by amputation; these fractures can heal and limb salvage can be performed when indicated. PMID:23610658

  19. Studies on groundwater transport in fractured crystalline rock under controlled conditions using nonradioactive tracers

    International Nuclear Information System (INIS)

    Gustafsson, E.; Klockars, C.-E.

    1981-04-01

    The purpose of the investigation has been study the following parameters along existing fractures between two boreholes: hydraulic properties of rock mass and fractures; adsorptive properties of some selected tracers during transport along fractures; dispersivity and dilution of tracers during transport in fractures; kinematic porosity of fractured bedrock. The procedure has been to determine the hydraulic properties of a rock mass by means of conventional hydraulic testing methods in 100 m deep boreholes, and to study transport mechanisms and properties of selected tracers in a selected fracture zone between two boreholes. (Auth.)

  20. Fracture of the styloid process associated with the mandible fracture

    Directory of Open Access Journals (Sweden)

    K N Dubey

    2013-01-01

    Full Text Available Fracture of the styloid process (SP of temporal bone is an uncommon injuries. Fracture of the SP can be associated with the facial injuries including mandible fracture. However, injury to the SP may be concealed and missed diagnosis may lead to the improper or various unnecessary treatments. A rare case of SP fracture associated with the ipsilateral mandibular fracture and also the diagnostic and management considerations of the SP fracture are discussed.

  1. 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

  2. Comparison of tibial shaft ski fractures in children and adults.

    Science.gov (United States)

    Hamada, Tomo; Matsumoto, Kazu; Ishimaru, Daichi; Sumi, Hiroshi; Shimizu, Katsuji

    2014-09-01

    To examine whether child and adult skiers have different risk factors or mechanisms of injury for tibial shaft fractures. Descriptive epidemiological study. Prospectively analyzed the epidemiologic factors, injury types, and injury mechanisms at Sumi Memorial Hospital. This study analyzed information obtained from 276 patients with tibial fractures sustained during skiing between 2004 and 2012. We focused on 174 ski-related tibial shaft fractures with respect to the following factors: age, gender, laterality of fracture, skill level, mechanism of fracture (fall vs collision), scene of injury (steepness of slope), snow condition, and weather. Fracture pattern was graded according to Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification and mechanical direction [external (ER) or internal rotation (IR)]. Tibial shaft fractures were the most common in both children (89.3%) and adults (47.4%). There were no significant differences in gender, side of fracture, mechanism of fracture, snow condition, or weather between children and adults. Skill levels were significantly lower in children than in adults (P differences in some of these parameters, suggesting that child and adult skiers have different risk factors or mechanisms of injury for tibial shaft fractures.

  3. CT findings predictive of neurological deficits in throracolumbar burst fractures

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Tae Yong; Jeong, Hee Seok; Jeong, Yeo Jin [Pusan National University and Research Institute for Convergence of Biomedical Science and Technology, Dept. of Radiology, Pusan National University Yangsan Hospital, Yangsan (Korea, Republic of); Lee, In Sook [Dept. of Radiology, Pusan National University Hospital, Busan (Korea, Republic of)

    2016-09-15

    To determine the computed tomography (CT) findings predictive of neurological deficits in thoracolumbar spine injuries. One hundred two patients with thoracolumbar spinal burst fractures, after excluding the patients with brain and cervical cord injuries and unconsciousness, who underwent consecutive spine 128-multidetector CT scan formed the study group. The neurological findings were clinically classified as no deficit (n = 58), complete deficit with paraplegia (n = 22), and incomplete deficit with either motor or sensory impairment (n = 22). The following four CT imaging parameters were analyzed: the level of the main burst fracture as the cord (n = 44) and the cauda equina (n = 58) levels; the extent of canal encroachment as central canal ratios (CCRs) below 0.5 (n = 43) and above 0.5 (n = 59); the degree of laminar fracture as no fracture (n = 33), linear fracture (n = 7), separated fracture (n = 27), and displaced fracture (n = 35); fractured vertebra counted as single (n = 53) and multiple (n = 49). Complete neurological deficit was associated with injuries at the cord level (p = 0.000) and displaced laminar fractures (p = 0.000); incomplete neurological deficit was associated with CCRs below 0.5 (p = 0.000) and multiple vertebral injuries (p = 0.002). CT scan can provide additional findings predictive of neurological deficits in thoracolumbar spinal burst fractures.

  4. Return to sports after ankle fractures: a systematic review.

    Science.gov (United States)

    Del Buono, Angelo; Smith, Rebecca; Coco, Manuela; Woolley, Laurence; Denaro, Vincenzo; Maffulli, Nicola

    2013-01-01

    This review aims to provide information on the time athletes will take to resume sports activity following ankle fractures. We systematically searched Medline (PubMED), EMBASE, CINHAL, Cochrane, Sports Discus and Google scholar databases using the combined keywords 'ankle fractures', 'ankle injuries', 'athletes', 'sports', 'return to sport', 'recovery', 'operative fixation', 'pinning', 'return to activity' to identify articles published in English, Spanish, French, Portuguese and Italian. Seven retrospective studies fulfilled our inclusion criteria. Of the 793 patients, 469 (59%) were males and 324 (41%) were females, and of the 356 ankle fractures we obtained information on, 338 were acute and 18 stress fractures. The general principles were to undertake open reduction and internal fixation of acute fractures, and manage stress fractures conservatively unless a thin fracture line was visible on radiographs. The best timing to return to sports after an acute ankle fracture is still undefined, given the heterogeneity of the outcome measures and results. The time to return to sports after an acute stress injury ranged from 3 to 51 weeks. When facing athletes with ankle fractures, associated injuries have to be assessed and addressed to improve current treatment lines and satisfy future expectancies. The best timing to return to sports after an ankle fracture has not been established yet. The ideas of the return to activity parameter and surgeon databases including sports-related information could induce research to progress.

  5. Characterisation of Fractures and Fracture Zones in a Carbonate Aquifer Using Electrical Resistivity Tomography and Pricking Probe Methodes

    Science.gov (United States)

    Szalai, Sandor; Kovacs, Attila; Kuslits, Lukács; Facsko, Gabor; Gribovszki, Katalin; Kalmar, Janos; Szarka, Laszlo

    2018-04-01

    Position, width and fragmentation level of fracture zones and position, significance and characteristic distance of fractures were aimed to determine in a carbonate aquifer. These are fundamental parameters, e.g. in hydrogeological modelling of aquifers, due to their role in subsurface water movements. The description of small scale fracture systems is however a challenging task. In the test area (Kádárta, Bakony Mts, Hungary), two methods proved to be applicable to get reasonable information about the fractures: Electrical Resistivity Tomography (ERT) and Pricking-Probe (PriP). PriP is a simple mechanical tool which has been successfully applied in archaeological investigations. ERT results demonstrated its applicability in this small scale fracture study. PriP proved to be a good verification tool both for fracture zone mapping and detecting fractures, but in certain areas, it produced different results than the ERT. The applicability of this method has therefore to be tested yet, although its problems most probably origin from human activity which reorganises the near-surface debris distribution. In the test site, both methods displayed fracture zones including a very characteristic one and a number of individual fractures and determined their characteristic distance and significance. Both methods prove to be able to produce hydrogeologically important parameters even individually, but their simultaneous application is recommended to decrease the possible discrepancies.

  6. The Process of Hydraulic Fracturing

    Science.gov (United States)

    Hydraulic fracturing, know as fracking or hydrofracking, produces fractures in a rock formation by pumping fluids (water, proppant, and chemical additives) at high pressure down a wellbore. These fractures stimulate the flow of natural gas or oil.

  7. Progressive fracture of polymer matrix composite structures: A new approach

    Science.gov (United States)

    Chamis, C. C.; Murthy, P. L. N.; Minnetyan, L.

    1992-01-01

    A new approach independent of stress intensity factors and fracture toughness parameters has been developed and is described for the computational simulation of progressive fracture of polymer matrix composite structures. The damage stages are quantified based on physics via composite mechanics while the degradation of the structural behavior is quantified via the finite element method. The approach account for all types of composite behavior, structures, load conditions, and fracture processes starting from damage initiation, to unstable propagation and to global structural collapse. Results of structural fracture in composite beams, panels, plates, and shells are presented to demonstrate the effectiveness and versatility of this new approach. Parameters and guidelines are identified which can be used as criteria for structural fracture, inspection intervals, and retirement for cause. Generalization to structures made of monolithic metallic materials are outlined and lessons learned in undertaking the development of new approaches, in general, are summarized.

  8. Fracture toughness of irradiated and recovered vessel steels

    International Nuclear Information System (INIS)

    Perosanz, F.; Lapena, J.

    1998-01-01

    This paper presents the fracture toughness measurements carried out on three vessel steels in an irradiated condition and after a post-irradiation recovery treatment. A statistical approach and the fracture parameters corresponding to two theoretical models of the fracture tests are used for evaluating toughness. Test results show that the neutron fluence gradually transforms the fracture behaviour of the vessel steels from ductile to brittle and seriously reduces their fracture toughness. The effectiveness of the recovery treatment, as evaluated from the toughness measurements, is confirmed, although the efficiency is not the same for the steels and depends on the evaluation parameter except in the case of almost complete recovery. The recovery effect increases with the received neutron fluence if the toughness values after treatment are compared with those in the irradiated condition rather than those in the as received condition. (orig.)

  9. Geometry, mechanics and transmissivity of rock fractures

    International Nuclear Information System (INIS)

    Lanaro, F.

    2001-04-01

    This thesis work investigates methods and tools for characterising, testing and modelling the behaviour of rock fractures. Using a 3D-laser-scanning technique, the topography of the surfaces and their position with respect to one another are measured. From the fracture topography, fracture roughness, angularity and aperture are quantified; the major features used for characterisation. The standard deviations for the asperity heights, surface slopes and aperture are determined. These statistical parameters usually increase/decrease according to power laws of the sampling size, and sometimes reach a sill beyond which they become constant. Also the number of contact spots with a certain area decreases according to a power-law function of the area. These power-law relations reveal the self affine fractal nature of roughness and aperture. Roughness is 'persistent' while aperture varies between 'persistent' and 'anti-persistent' probably depending on the degree of match of the fracture walls. The fractal models for roughness, aperture and contact area are used to develop a constitutive model, based on contact mechanics, for describing the fracture normal and shear deformability. The experimental testing results of normal deformability are simulated well by the model whereas fracture shear deformability is not as well modelled. The model predicts well fracture dilation but is too stiff compared to rock samples. A mathematical description of the aperture pattern during shearing is also formulated. The mean value and covariance of the aperture in shearing is calculated and verifies reported observations. The aperture map of samples is inserted in a numerical program for flow calculation. The 'integral transform method' is used for solving the Reynolds' equation; it transforms the fracture transmissivity pattern into a frequency-based function. This closely resembles the power laws that describe fractals. This function can be described directly from the fractal properties of

  10. [Trochanteric femoral fractures].

    Science.gov (United States)

    Douša, P; Čech, O; Weissinger, M; Džupa, V

    2013-01-01

    At the present time proximal femoral fractures account for 30% of all fractures referred to hospitals for treatment. Our population is ageing, the proportion of patients with post-menopausal or senile osteoporosis is increasing and therefore the number of proximal femoral fractures requiring urgent treatment is growing too. In the age category of 50 years and older, the incidence of these fractures has increased exponentially. Our department serves as a trauma centre for half of Prague and part of the Central Bohemia Region with a population of 1 150 000. Prague in particular has a high number of elderly citizens. Our experience is based on extensive clinical data obtained from the Register of Proximal Femoral Fractures established in 1997. During 14 years, 4280 patients, 3112 women and 1168 men, were admitted to our department for treatment of proximal femoral fractures. All patients were followed up until healing or development of complications. In the group under study, 82% were patients older than 70 years; 72% of those requiring surgery were in their seventies and eighties. Men were significantly younger than women (pfractures were 2.3-times more frequent in women than in men. In the category under 60 years, men significantly outnumbered women (pfractures were, on the average, eight years older than the patients with intertrochanteric fractures, which is a significant difference (pTrochanteric fractures accounted for 54.7% and femoral neck fractures for 45.3% of all fractures. The inter-annual increase was 5.9%, with more trochanteric than femoral neck fractures. There was a non-significant decrease in intertrochanteric (AO 31-A3) fractures. On the other hand, the number of pertrochanteric (AO 31-A1+2) fractures increased significantly (pfractures were treated with a proximal femoral nail; a short nail was used in 1260 and a long nail in 134 of them. A dynamic hip screw (DHS) was employed to treat 947 fractures. Distinguishing between pertrochanteric (21-A1

  11. Radionuclide transport in fractured porous media -- Analytical solutions for a system of parallel fractures with a constant inlet flux

    International Nuclear Information System (INIS)

    Chen, C.T.; Li, S.H.

    1997-01-01

    Analytical solutions are developed for the problem of radionuclide transport in a system of parallel fractures situated in a porous rock matrix. A constant flux is used as the inlet boundary condition. The solutions consider the following processes: (a) advective transport along the fractures; (b) mechanical dispersion and molecular diffusion along the fractures; (c) molecular diffusion from a fracture to the porous matrix; (d) molecular diffusion within the porous matrix in the direction perpendicular to the fracture axis; (e) adsorption onto the fracture wall; (f) adsorption within the porous matrix, and (g) radioactive decay. The solutions are based on the Laplace transform method. The general transient solution is in the form of a double integral that is evaluated using composite Gauss-Legendre quadrature. A simpler transient solution that is in the form of a single integral is also presented for the case that assumes negligible longitudinal dispersion along the fractures. The steady-state solutions are also provided. A number of examples are given to illustrate the effects of various important parameters, including: (a) fracture spacing; (b) fracture dispersion coefficient; (c) matrix diffusion coefficient; (d) fracture width; (e) groundwater velocity; (f) matrix retardation factor; and (g) matrix porosity

  12. Fracture resistance of welded panel specimen with perpendicular crack in tensile

    International Nuclear Information System (INIS)

    Gochev, Todor; Adziev, Todor

    1998-01-01

    Defects caused by natural crack in welded joints of high-strength low-alloy (HSLA) steels are very often. Perpendicular crack in welded joints and its heat treatment after the welding has also an influence on the fracture resistance. The fracture resistance of welded joints by crack in tense panel specimens was investigated by crack mouse opening displesment (CMOD), the parameter of fracture mechanic. Crack propagation was analysed by using a metallographic analysis of fractured specimens after the test. (Author)

  13. Hand fracture - aftercare

    Science.gov (United States)

    ... an orthopedic surgeon if: Your metacarpal bones are broken and shifted out of place Your fingers do not line up correctly Your fracture nearly went through the skin Your fracture went through the skin Your pain is severe or becoming worse Self-care at Home You may have pain and swelling for 1 ...

  14. Physeal Fractures in Foals.

    Science.gov (United States)

    Levine, David G; Aitken, Maia R

    2017-08-01

    Physeal fractures are common musculoskeletal injuries in foals and should be included as a differential diagnosis for the lame or nonweightbearing foal. Careful evaluation of the patient, including precise radiographic assessment, is paramount in determining the options for treatment. Prognosis mostly depends on the patient's age, weight, and fracture location and configuration. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. A New Method for Fracturing Wells Reservoir Evaluation in Fractured Gas Reservoir

    Directory of Open Access Journals (Sweden)

    Jianchun Guo

    2014-01-01

    Full Text Available Natural fracture is a geological phenomenon widely distributed in tight formation, and fractured gas reservoir stimulation effect mainly depends on the communication of natural fractures. Therefore it is necessary to carry out the evaluation of this reservoir and to find out the optimal natural fractures development wells. By analyzing the interactions and nonlinear relationships of the parameters, it establishes three-level index system of reservoir evaluation and proposes a new method for gas well reservoir evaluation model in fractured gas reservoir on the basis of fuzzy logic theory and multilevel gray correlation. For this method, the Gaussian membership functions to quantify the degree of every factor in the decision-making system and the multilevel gray relation to determine the weight of each parameter on stimulation effect. Finally through fuzzy arithmetic operator between multilevel weights and fuzzy evaluation matrix, score, rank, the reservoir quality, and predicted production will be gotten. Result of this new method shows that the evaluation of the production coincidence rate reaches 80%, which provides a new way for fractured gas reservoir evaluation.

  16. Optimization of flow modeling in fractured media with discrete fracture network via percolation theory

    Science.gov (United States)

    Donado-Garzon, L. D.; Pardo, Y.

    2013-12-01

    Fractured media are very heterogeneous systems where occur complex physical and chemical processes to model. One of the possible approaches to conceptualize this type of massifs is the Discrete Fracture Network (DFN). Donado et al., modeled flow and transport in a granitic batholith based on this approach and found good fitting with hydraulic and tracer tests, but the computational cost was excessive due to a gigantic amount of elements to model. We present in this work a methodology based on percolation theory for reducing the number of elements and in consequence, to reduce the bandwidth of the conductance matrix and the execution time of each network. DFN poses as an excellent representation of all the set of fractures of the media, but not all the fractures of the media are part of the conductive network. Percolation theory is used to identify which nodes or fractures are not conductive, based on the occupation probability or percolation threshold. In a fractured system, connectivity determines the flow pattern in the fractured rock mass. This volume of fluid is driven through connection paths formed by the fractures, when the permeability of the rock is negligible compared to the fractures. In a population of distributed fractures, each of this that has no intersection with any connected fracture do not contribute to generate a flow field. This algorithm also permits us to erase these elements however they are water conducting and hence, refine even more the backbone of the network. We used 100 different generations of DFN that were optimized in this study using percolation theory. In each of the networks calibrate hydrodynamic parameters as hydraulic conductivity and specific storage coefficient, for each of the five families of fractures, yielding a total of 10 parameters to estimate, at each generation. Since the effects of the distribution of fault orientation changes the value of the percolation threshold, but not the universal laws of classical

  17. Treatment of midfacial fractures

    International Nuclear Information System (INIS)

    Schubert, J.

    2007-01-01

    Fractures of the midface constitute half of all traumas involving facial bones. Computed tomography is very useful in primary diagnosis. Isolated fractures of the nasal bone and lateral midfacial structures may be diagnosed sufficiently by conventional X-rays. An exact description of the fracture lines along the midfacial buttresses is essential for treatment planning. For good aesthetics and function these have to be reconstructed accurately, which can be checked with X-rays. The treatment of midfacial fractures has been revolutionized over the last two decades. A stable three-dimensional reconstruction of the facial shape is now possible and the duration of treatment has shortened remarkably. The frequently occurring isolated fractures in the lateral part of the midface may be treated easily and effectively by semisurgical methods such as the Gillies procedure or hook-repositioning. (orig.)

  18. Dating fractures in infants

    Energy Technology Data Exchange (ETDEWEB)

    Halliday, K.E., E-mail: kath.halliday@nuh.nhs.uk [Department of Radiology, Nottingham University Hospitals, Queen' s Medical Centre, Nottingham (United Kingdom); Broderick, N J; Somers, J M [Department of Radiology, Nottingham University Hospitals, Queen' s Medical Centre, Nottingham (United Kingdom); Hawkes, R [Department of Radiology, Paul O' Gorman Building, Bristol (United Kingdom)

    2011-11-15

    Aim: To document the timing of the appearance of the radiological features of fracture healing in a group of infants in which the date of injury was known and to assess the degree of interobserver agreement. Materials and methods: Three paediatric radiologists independently assessed 161 images of 37 long bone fractures in 31 patients aged 0-44 months. The following features were assessed: soft-tissue swelling, subperiosteal new bone formation (SPNBF), definition of fracture line, presence or absence of callus, whether callus was well or ill defined, and the presence of endosteal callus. Results: Agreement between observers was only moderate for all discriminators except SPNBF. SPNBF was invariably seen after 11 days but was uncommon before this time even in the very young. In one case SPNBF was seen at 4 days. Conclusion: With the exception of SPNBF, the criteria relied on to date fractures are either not reproducible or are poor discriminators of fracture age.

  19. Dating fractures in infants

    International Nuclear Information System (INIS)

    Halliday, K.E.; Broderick, N.J.; Somers, J.M.; Hawkes, R.

    2011-01-01

    Aim: To document the timing of the appearance of the radiological features of fracture healing in a group of infants in which the date of injury was known and to assess the degree of interobserver agreement. Materials and methods: Three paediatric radiologists independently assessed 161 images of 37 long bone fractures in 31 patients aged 0-44 months. The following features were assessed: soft-tissue swelling, subperiosteal new bone formation (SPNBF), definition of fracture line, presence or absence of callus, whether callus was well or ill defined, and the presence of endosteal callus. Results: Agreement between observers was only moderate for all discriminators except SPNBF. SPNBF was invariably seen after 11 days but was uncommon before this time even in the very young. In one case SPNBF was seen at 4 days. Conclusion: With the exception of SPNBF, the criteria relied on to date fractures are either not reproducible or are poor discriminators of fracture age.

  20. Tibial Plateau Fractures

    DEFF Research Database (Denmark)

    Elsøe, Rasmus

    This PhD thesis reported an incidence of tibial plateau fractures of 10.3/100,000/year in a complete Danish regional population. The results reported that patients treated for a lateral tibial plateau fracture with bone tamp reduction and percutaneous screw fixation achieved a satisfactory level...... with only the subgroup Sport significantly below the age matched reference population. The thesis reports a level of health related quality of life (Eq5d) and disability (KOOS) significantly below established reference populations for patients with bicondylar tibial plateau fracture treated with a ring...... fixator, both during treatment and at 19 months following injury. In general, the thesis demonstrates that the treatment of tibial plateau fractures are challenging and that some disabilities following these fractures must be expected. Moreover, the need for further research in the area, both with regard...

  1. Fracturing formations in wells

    Energy Technology Data Exchange (ETDEWEB)

    Daroza, R A

    1964-05-15

    This well stimulation method comprises introducing through the well bore a low-penetrating, dilatant fluid, and subjecting the fluid to sufficient pressure to produce fractures in the formation. The fluid is permitted to remain in contact with the formation so as to become diluted by the formation fluids, and thereby lose its properties of dilatancy. Also, a penetrating fluid, containing a propping agent suspended therein, in introduced into contact with the fractures at a pressure substantially reduced with respect to that pressure which would have been required, prior to the fracturing operation performed using the low-penetrating dilatant fluid. The propping agent is deposited within the fractures, and thereafter, fluid production is resumed from the fractured formation. (2 claims)

  2. Anisotropic composite human skull model and skull fracture validation against temporo-parietal skull fracture.

    Science.gov (United States)

    Sahoo, Debasis; Deck, Caroline; Yoganandan, Narayan; Willinger, Rémy

    2013-12-01

    A composite material model for skull, taking into account damage is implemented in the Strasbourg University finite element head model (SUFEHM) in order to enhance the existing skull mechanical constitutive law. The skull behavior is validated in terms of fracture patterns and contact forces by reconstructing 15 experimental cases. The new SUFEHM skull model is capable of reproducing skull fracture precisely. The composite skull model is validated not only for maximum forces, but also for lateral impact against actual force time curves from PMHS for the first time. Skull strain energy is found to be a pertinent parameter to predict the skull fracture and based on statistical (binary logistical regression) analysis it is observed that 50% risk of skull fracture occurred at skull strain energy of 544.0mJ. © 2013 Elsevier Ltd. All rights reserved.

  3. Discrete fracture network for the Forsmark site

    Energy Technology Data Exchange (ETDEWEB)

    Darcel, C. [Itasca Consultants, Ecully (France); Davy, P.; Bour, O.; Dreuzy, J.R. de [Geosciences, Rennes (France)

    2006-08-15

    In this report, we aim at defining a self-consistent method for analyzing the fracture patterns from boreholes, outcrops and lineaments. The objective was both to point out some variations in the fracture network parameters, and to define the global scaling fracture models that can encompass all the constraints brought by the different datasets. Although a full description of the DFN model variability is obviously fundamental for the future, we have put emphasis on the determination of mean parameters. The main parameters of the disc-shaped DFN model are the fracture size, orientations and spatial density distribution. The scaling model is defined as an extrapolation of existing i) observations at specific scales and ii) local fitting models to the whole range of scales. The range of possible models is restricted to the power-law scaling models. During the project we have put emphasize on the definition of the theory and methodology necessary to assess a sound comparison between data taken at different scales, with different techniques. Both 'local' and 'global' models have been investigated. Local models are linked exactly to the dataset they represent. Then, the global DFN models arise from the association of local models, different scales and different sample support shapes. Discrepancies between local and global model illustrate the variability associated to the DFN models. We define two possible Global Scaling Models (GSM). The first one is consistent with the scaling measured in the outcrops (Model A). Its scaling exponent is a{sub 3d}=3.5 (eq. to k{sub r}=2.5); it overestimates the fracture densities observed in the lineament maps. The second one assumes that both lineaments and outcrops belong to the same distribution model (Model B), which entails a scaling exponent a{sub 3d}=3.9 (eq. to k{sub r}=2.9). Both models have been tested by looking for the best consistency in the fracture density-dip relationships, between boreholes data at

  4. Discrete fracture network for the Forsmark site

    International Nuclear Information System (INIS)

    Darcel, C.; Davy, P.; Bour, O.; Dreuzy, J.R. de

    2006-08-01

    In this report, we aim at defining a self-consistent method for analyzing the fracture patterns from boreholes, outcrops and lineaments. The objective was both to point out some variations in the fracture network parameters, and to define the global scaling fracture models that can encompass all the constraints brought by the different datasets. Although a full description of the DFN model variability is obviously fundamental for the future, we have put emphasis on the determination of mean parameters. The main parameters of the disc-shaped DFN model are the fracture size, orientations and spatial density distribution. The scaling model is defined as an extrapolation of existing i) observations at specific scales and ii) local fitting models to the whole range of scales. The range of possible models is restricted to the power-law scaling models. During the project we have put emphasize on the definition of the theory and methodology necessary to assess a sound comparison between data taken at different scales, with different techniques. Both 'local' and 'global' models have been investigated. Local models are linked exactly to the dataset they represent. Then, the global DFN models arise from the association of local models, different scales and different sample support shapes. Discrepancies between local and global model illustrate the variability associated to the DFN models. We define two possible Global Scaling Models (GSM). The first one is consistent with the scaling measured in the outcrops (Model A). Its scaling exponent is a 3d =3.5 (eq. to k r =2.5); it overestimates the fracture densities observed in the lineament maps. The second one assumes that both lineaments and outcrops belong to the same distribution model (Model B), which entails a scaling exponent a 3d =3.9 (eq. to k r =2.9). Both models have been tested by looking for the best consistency in the fracture density-dip relationships, between boreholes data at depth (based on boreholes KFM02A, KFM

  5. Studies of fracture network geometry of reservoir outcrop analogues from terrestrial lidar data: attempts to quantify spatial variations of fracture characteristics

    Science.gov (United States)

    Vsemirnova, E. A.; Jones, R. R.; McCaffrey, K. J. W.

    2012-04-01

    We describe studies analysing terrestrial lidar datasets of fracture systems from a range of reservoir analogues in clastic and carbonate lithologies that represent geological analogues of offshore hydrocarbon reservoirs for the UK continental shelf. As fracture networks (observed here from centimetre to kilometre scale) can significantly affect the permeability of a fractured reservoir, the definition of fracture network geometry at various scales has become an important goal of structural analysis. The main aim of the study has been to extend the investigation of fracture networks in order to quantify spatial variations in fracture parameters in a variety of lithologies. The datasets were pre-processed using RiSCAN PRO software, and then re-sampled and filtered to derive characteristics which are traditionally measured from outcrops, including size distributions, fracture spacing and clustering statistics. This type of analysis can significantly reduce the uncertainty associated with some field fracture network measurements. The digitised fracture networks datasets are then used to investigate various aspects of spatial heterogeneity. A series of fracture maps (joints and faults) were generated at different scales, and fracture trends were studied to test scale dependency of fracture orientations. Multiscale trend analysis was then applied to describe the trend structure of the fracture networks.

  6. Employing Eigenvalue Ratios to Generate Prior Fracture-like Features for Stochastic Hydrogeophysical Characterization of a Fractured Aquifer System

    Science.gov (United States)

    Brewster, J.; Oware, E. K.

    2017-12-01

    Groundwater hosted in fractured rocks constitutes almost 65% of the principal aquifers in the US. The exploitation and contaminant management of fractured aquifers require fracture flow and transport modeling, which in turn requires a detailed understanding of the structure of the aquifer. The widely used equivalent porous medium approach to modeling fractured aquifer systems is inadequate to accurately predict fracture transport processes due to the averaging of the sharp lithological contrast between the matrix and the fractures. The potential of geophysical imaging (GI) to estimate spatially continuous subsurface profiles in a minimally invasive fashion is well proven. Conventional deterministic GI strategies, however, produce geologically unrealistic, smoothed-out results due to commonly enforced smoothing constraints. Stochastic GI of fractured aquifers is becoming increasing appealing due to its ability to recover realistic fracture features while providing multiple likely realizations that enable uncertainty assessment. Generating prior spatial features consistent with the expected target structures is crucial in stochastic imaging. We propose to utilize eigenvalue ratios to resolve the elongated fracture features expected in a fractured aquifer system. Eigenvalues capture the major and minor directions of variability in a region, which can be employed to evaluate shape descriptors, such as eccentricity (elongation) and orientation of features in the region. Eccentricity ranges from zero to one, representing a circularly sharped to a line feature, respectively. Here, we apply eigenvalue ratios to define a joint objective parameter consisting of eccentricity (shape) and direction terms to guide the generation of prior fracture-like features in some predefined principal directions for stochastic GI. Preliminary unconditional, synthetic experiments reveal the potential of the algorithm to simulate prior fracture-like features. We illustrate the strategy with a

  7. Modelling of ductile and cleavage fracture by local approach

    International Nuclear Information System (INIS)

    Samal, M.K.; Dutta, B.K.; Kushwaha, H.S.

    2000-08-01

    This report describes the modelling of ductile and cleavage fracture processes by local approach. It is now well known that the conventional fracture mechanics method based on single parameter criteria is not adequate to model the fracture processes. It is because of the existence of effect of size and geometry of flaw, loading type and rate on the fracture resistance behaviour of any structure. Hence, it is questionable to use same fracture resistance curves as determined from standard tests in the analysis of real life components because of existence of all the above effects. So, there is need to have a method in which the parameters used for the analysis will be true material properties, i.e. independent of geometry and size. One of the solutions to the above problem is the use of local approaches. These approaches have been extensively studied and applied to different materials (including SA33 Gr.6) in this report. Each method has been studied and reported in a separate section. This report has been divided into five sections. Section-I gives a brief review of the fundamentals of fracture process. Section-II deals with modelling of ductile fracture by locally uncoupled type of models. In this section, the critical cavity growth parameters of the different models have been determined for the primary heat transport (PHT) piping material of Indian pressurised heavy water reactor (PHWR). A comparative study has been done among different models. The dependency of the critical parameters on stress triaxiality factor has also been studied. It is observed that Rice and Tracey's model is the most suitable one. But, its parameters are not fully independent of triaxiality factor. For this purpose, a modification to Rice and Tracery's model is suggested in Section-III. Section-IV deals with modelling of ductile fracture process by locally coupled type of models. Section-V deals with the modelling of cleavage fracture process by Beremins model, which is based on Weibulls

  8. Computed tomograms of blowout fracture

    International Nuclear Information System (INIS)

    Ito, Haruhide; Hayashi, Minoru; Shoin, Katsuo; Hwang, Wen-Zern; Yamamoto, Shinjiro; Yonemura, Taizo.

    1985-01-01

    We studied 18 cases of orbital fractures, excluding optic canal fracture. There were 11 cases of pure blowout fracture and 3 of the impure type. The other 4 cases were orbital fractures without blowout fracture. The cardinal syndromes were diplopia, enophthalmos, and sensory disturbances of the trigeminal nerve in the pure type of blowout fracture. Many cases of the impure type of blowout fracture or of orbital fracture showed black eyes or a swelling of the eyelids which masked enophthalmos. Axial and coronal CT scans demonstrated: 1) the orbital fracture, 2) the degree of enophthalmos, 3) intraorbital soft tissue, such as incarcerated or prolapsed ocular muscles, 4) intraorbital hemorrhage, 5) the anatomical relation of the orbital fracture to the lacrimal canal, the trochlea, and the trigeminal nerve, and 6) the lesions of the paranasal sinus and the intracranial cavity. CT scans play an important role in determining what surgical procedures might best be employed. Pure blowout fractures were classified by CT scans into these four types: 1) incarcerating linear fracture, 2) trapdoor fracture, 3) punched-out fracture, and 4) broad fracture. Cases with severe head injury should be examined to see whether or not blowout fracture is present. If the patients are to hope to return to society, a blowout fracture should be treated as soon as possible. (author)

  9. Computed tomograms of blowout fracture

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Haruhide; Hayashi, Minoru; Shoin, Katsuo; Hwang, Wen-Zern; Yamamoto, Shinjiro; Yonemura, Taizo

    1985-02-01

    We studied 18 cases of orbital fractures, excluding optic canal fracture. There were 11 cases of pure blowout fracture and 3 of the impure type. The other 4 cases were orbital fractures without blowout fracture. The cardinal syndromes were diplopia, enophthalmos, and sensory disturbances of the trigeminal nerve in the pure type of blowout fracture. Many cases of the impure type of blowout fracture or of orbital fracture showed black eyes or a swelling of the eyelids which masked enophthalmos. Axial and coronal CT scans demonstrated: 1) the orbital fracture, 2) the degree of enophthalmos, 3) intraorbital soft tissue, such as incarcerated or prolapsed ocular muscles, 4) intraorbital hemorrhage, 5) the anatomical relation of the orbital fracture to the lacrimal canal, the trochlea, and the trigeminal nerve, and 6) the lesions of the paranasal sinus and the intracranial cavity. CT scans play an important role in determining what surgical procedures might best be employed. Pure blowout fractures were classified by CT scans into these four types: 1) incarcerating linear fracture, 2) trapdoor fracture, 3) punched-out fracture, and 4) broad fracture. Cases with severe head injury should be examined to see whether or not blowout fracture is present. If the patients are to hope to return to society, a blowout fracture should be treated as soon as possible. (author).

  10. Radiological diagnosis of fractures

    International Nuclear Information System (INIS)

    Finlay, D.B.L.; Allen, M.J.

    1984-01-01

    This book is about radiology of fractures. While it contains sections of clinical features it is not intended that readers should rely entirely upon these for the diagnosis and management of the injured patient. As in the diagnosis and treatment of all medical problems, fracture management must be carried out in a logical step-by-step fashion - namely, history, examination, investigation, differential diagnosis, diagnosis and then treatment. Each section deals with a specific anatomical area and begins with line drawings of the normal radiographs demonstrating the anatomy. Accessory views that may be requested, and the indications for these, are included. Any radiological pitfalls for the area in general are then described. The fractures in adults are then examined in turn, their radiological features described, and any pitfalls in their diagnosis discussed. A brief note of important clinical findings is included. A brief mention is made of pediatric fractures which are of significance and their differences to the adult pattern indicated. Although fractures can be classified into types with different characteristics, in life every fracture is individual. Fractures by and large follow common patterns, but many have variations

  11. Spontaneous rib fractures.

    Science.gov (United States)

    Katrancioglu, Ozgur; Akkas, Yucel; Arslan, Sulhattin; Sahin, Ekber

    2015-07-01

    Other than trauma, rib fracture can occur spontaneously due to a severe cough or sneeze. In this study, patients with spontaneous rib fractures were analyzed according to age, sex, underlying pathology, treatment, and complications. Twelve patients who presented between February 2009 and February 2011 with spontaneous rib fracture were reviewed retrospectively. The patients' data were evaluated according to anamnesis, physical examination, and chest radiographs. The ages of the patients ranged from 34 to 77 years (mean 55.91 ± 12.20 years), and 7 (58.4%) were male. All patients had severe cough and chest pain. The fractures were most frequently between 4th and 9th ribs; multiple rib fractures were detected in 5 (41.7%) patients. Eight (66.7%) patients had chronic obstructive pulmonary disease, 2 (16.7%) had bronchial asthma, and 2 (16.7%) had osteoporosis. Bone densitometry revealed a high risk of bone fracture in all patients. Patients with chronic obstructive pulmonary disease or bronchial asthma had been treated with high-dose steroids for over a year. Spontaneous rib fracture due to severe cough may occur in patients with osteoporosis, chronic obstructive pulmonary disease, or bronchial asthma, receiving long-term steroid therapy. If these patients have severe chest pain, chest radiography should be performed to check for bone lesions. © The Author(s) 2015.

  12. Why ductile fracture mechanics

    International Nuclear Information System (INIS)

    Ritchie, R.O.

    1983-01-01

    Until recently, the engineering application of fracture mechanics has been specific to a description of macroscopic fracture behavior in components and structural parts which remain nominally elastic under loading. While this approach, termed linear elastic fracture mechanics, has been found to be invaluable for the continuum analysis of crack growth in brittle and high strength materials, it is clearly inappropriate for characterizing failure in lower strength ductile alloys where extensive inelastic deformation precedes and accompanies crack initiation and subsequent propagation. Accordingly, much effort has been devoted in recent years toward the development of nonlinear or ductile fracture mechanics methodology to characterize fracture behavior under elastic/plastic conditions; an effort which has been principally motivated by problems in nuclear industry. In this paper, the concepts of ductile (elastic/plastic) fracture mechanics are introduced and applied to the problem of both stationary and nonstationary cracks. Specifically, the limitations inherent in this approach are defined, together with a description of the microstructural considerations and applications relevant to the failure of ductile materials by fracture, fatigue, and creep

  13. Orbital wall fractures

    International Nuclear Information System (INIS)

    Iinuma, Toshitaka; Ishio, Ken-ichirou; Yoshinami, Hiroyoshi; Kuriyama, Jun-ichi; Hirota, Yoshiharu.

    1993-01-01

    A total of 59 cases of mild facial fractures (simple orbital wall fractures, 34 cases, other facial fractures, 25 cases) with the clinical suspects of orbital wall fractures were evaluated both by conventional views (Waters' and Caldwell views) and coronal CT scans. Conventional views were obtained, as an average, after 4 days and CT after 7 days of injuries. Both the medial wall and the floor were evaluated at two sites, i.e., anterior and posterior. The ethmoid-maxillary plate was also included in the study. The degree of fractures was classified as, no fractures, fractures of discontinuity, dislocation and fragmentation. The coronal CT images in bone window condition was used as reference and the findings were compared between conventional views and CT. The correct diagnosis was obtained as follows: orbital floor (anterior, 78%, posterior, 73%), medial orbital wall (anterior, 72%, posterior, 72%) and ethmoid-maxillary plate (64%). The false positive diagnosis was as follows: orbital floor (anterior only, 13%), medial orbital wall (anterior only, 7%) and ethmoid-maxillary plate (11%). The false negative diagnosis was as follows: orbital floor (anterior, 9%, posterior, 10%), medial orbital wall (anterior, 21%, posterior, 28%) and ethmoid-maxillary plate (21%). The results were compared with those of others in the past. (author)

  14. Chance Fracture Secondary to a Healed Kyphotic Compression Osteoporotic Fracture

    Directory of Open Access Journals (Sweden)

    Teh KK

    2009-11-01

    Full Text Available Chance fracture is an unstable vertebral fracture, which usually results from a high velocity injury. An elderly lady with a previously healed osteoporotic fracture of the T12 and L1 vertebra which resulted in a severe kyphotic deformity subsequently sustained a Chance fracture of the adjacent L2 vertebrae after a minor fall. The previously fracture left her with a deformity which resulted in significant sagittal imbalance therefore predisposing her to this fracture. This case highlights the importance of aggressive treatment of osteoporotic fractures in order to prevent significant sagittal imbalance from resultant (i.e. kyphotic deformity.

  15. An evaluation of fracture toughness of bituminous coal

    International Nuclear Information System (INIS)

    Pathan, A.G.

    2005-01-01

    The role of fracture mechanics in the design of rock structures is vitally important. However, because of the complexities of rock structures and lack of understanding of the fundamentals of the failure mechanism, it has become customary to use the engineering properties approach in the design of stable rock structures. Recently considerable attention has been given and attempts are being made to apply the fracture mechanics approach to the design of safe mining structures. In mining engineering the fracture mechanics may be applied to calculate the formation of fracture zones around mine opening, thus estimating support requirements and formulating guide lines for the selection of mine roadway support system. The research work presented here is concerned with the evaluation of fracture toughness of coal under laboratory conditions. Diametral compression test method is used to determine the fracture toughness parameter of coal in the opening model failure. The effect of crack length and dimensionless crack length on the fracture toughness was studied also. A laboratory investigation of fracture toughness of coal in tensile mode failure has led to the conclusion that fracture toughness could be treated as a material property. (author)

  16. Modelling Laccoliths: Fluid-Driven Fracturing in the Lab

    Science.gov (United States)

    Ball, T. V.; Neufeld, J. A.

    2017-12-01

    Current modelling of the formation of laccoliths neglects the necessity to fracture rock layers for propagation to occur [1]. In magmatic intrusions at depth the idea of fracture toughness is used to characterise fracturing, however an analogue for near surface intrusions has yet to be explored [2]. We propose an analytical model for laccolith emplacement that accounts for the energy required to fracture at the tip of an intrusion. For realistic physical parameters we find that a lag region exists between the fluid magma front and the crack tip where large negative pressures in the tip cause volatiles to exsolve from the magma. Crucially, the dynamics of this tip region controls the spreading due to the competition between viscous forces and fracture energy. We conduct a series of complementary experiments to investigate fluid-driven fracturing of adhered layers and confirm the existence of two regimes: viscosity dominant spreading, controlled by the pressure in the lag region, and fracture energy dominant spreading, controlled by the energy required to fracture layers. Our experiments provide the first observations, and evolution, of a vapour tip. These experiments and our simplified model provide insight into the key physical processes in near surface magmatic intrusions with applications to fluid-driven fracturing more generally. Michaut J. Geophys. Res. 116(B5), B05205. Bunger & Cruden J. Geophys. Res. 116(B2), B02203.

  17. Specification of matrix cleanup goals in fractured porous media.

    Science.gov (United States)

    Rodríguez, David J; Kueper, Bernard H

    2013-01-01

    Semianalytical transient solutions have been developed to evaluate what level of fractured porous media (e.g., bedrock or clay) matrix cleanup must be achieved in order to achieve compliance of fracture pore water concentrations within a specified time at specified locations of interest. The developed mathematical solutions account for forward and backward diffusion in a fractured porous medium where the initial condition comprises a spatially uniform, nonzero matrix concentration throughout the domain. Illustrative simulations incorporating the properties of mudstone fractured bedrock demonstrate that the time required to reach a desired fracture pore water concentration is a function of the distance between the point of compliance and the upgradient face of the domain where clean groundwater is inflowing. Shorter distances correspond to reduced times required to reach compliance, implying that shorter treatment zones will respond more favorably to remediation than longer treatment zones in which back-diffusion dominates the fracture pore water response. For a specified matrix cleanup goal, compliance of fracture pore water concentrations will be reached sooner for decreased fracture spacing, increased fracture aperture, higher matrix fraction organic carbon, lower matrix porosity, shorter aqueous phase decay half-life, and a higher hydraulic gradient. The parameters dominating the response of the system can be measured using standard field and laboratory techniques. © 2012, The Author(s). Ground Water © 2012, National Ground Water Association.

  18. Three-dimensional assessment of unilateral subcondylar fracture using computed tomography after open reduction

    Directory of Open Access Journals (Sweden)

    Sathya Kumar Devireddy

    2014-01-01

    Full Text Available Objective: The aim was to assess the accuracy of three-dimensional anatomical reductions achieved by open method of treatment in cases of displaced unilateral mandibular subcondylar fractures using preoperative (pre op and postoperative (post op computed tomography (CT scans. Materials and Methods: In this prospective study, 10 patients with unilateral sub condylar fractures confirmed by an orthopantomogram were included. A pre op and post op CT after 1 week of surgical procedure was taken in axial, coronal and sagittal plane along with three-dimensional reconstruction. Standard anatomical parameters, which undergo changes due to fractures of the mandibular condyle were measured in pre and post op CT scans in three planes and statistically analysed for the accuracy of the reduction comparing the following variables: (a Pre op fractured and nonfractured side (b post op fractured and nonfractured side (c pre op fractured and post op fractured side. P < 0.05 was considered as significant. Results: Three-dimensional anatomical reduction was possible in 9 out of 10 cases (90%. The statistical analysis of each parameter in three variables revealed (P < 0.05 that there was a gross change in the dimensions of the parameters obtained in pre op fractured and nonfractured side. When these parameters were assessed in post op CT for the three variables there was no statistical difference between the post op fractured side and non fractured side. The same parameters were analysed for the three variables in pre op fractured and post op fractured side and found significant statistical difference suggesting a considerable change in the dimensions of the fractured side post operatively. Conclusion: The statistical and clinical results in our study emphasised that it is possible to fix the condyle in three-dimensional anatomical positions with open method of treatment and avoid post op degenerative joint changes. CT is the ideal imaging tool and should be used on

  19. A Rare Nasal Bone Fracture: Anterior Nasal Spine Fracture

    Directory of Open Access Journals (Sweden)

    Egemen Kucuk

    2014-04-01

    Full Text Available Anterior nasal spine fractures are a quite rare type of nasal bone fractures. Associated cervical spine injuries are more dangerous than the nasal bone fracture. A case of the anterior nasal spine fracture, in a 18-year-old male was presented. Fracture of the anterior nasal spine, should be considered in the differential diagnosis of the midface injuries and also accompanying cervical spine injury should not be ignored.

  20. Fracture characteristics in Japanese rock

    International Nuclear Information System (INIS)

    Ijiri, Yuji; Sawada, Atsushi; Akahori, Kuniaki

    1999-11-01

    It is crucial for the performance assessment of geosphere to evaluate the characteristics of fractures that can be dominant radionuclide migration pathways from a repository to biosphere. This report summarizes the characteristics of fractures obtained from broad literature surveys and the fields surveys at the Kamaishi mine in northern Japan and at outcrops and galleries throughout the country. The characteristics of fractures described in this report are fracture orientation, fracture shape, fracture frequency, fracture distribution in space, transmissivity of fracture, fracture aperture, fracture fillings, alteration halo along fracture, flow-wetted surface area in fracture, and the correlation among these characteristics. Since granitic rock is considered the archetype fractured media, a large amount of fracture data is available in literature. In addition, granitic rock has been treated as a potential host rock in many overseas programs, and has JNC performed a number of field observations and experiments in granodiorite at the Kamaishi mine. Therefore, the characteristics of fractures in granitic rock are qualitatively and quantitatively clarified to some extent in this report, while the characteristics of fractures in another rock types are not clarified. (author)

  1. Aspects of modern fracture statistics

    International Nuclear Information System (INIS)

    Tradinik, W.; Pabst, R.F.; Kromp, K.

    1981-01-01

    This contribution begins with introductory general remarks about fracture statistics. Then the fundamentals of the distribution of fracture probability are described. In the following part the application of the Weibull Statistics is justified. In the fourth chapter the microstructure of the material is considered in connection with calculations made in order to determine the fracture probability or risk of fracture. (RW) [de

  2. 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...

  3. Vertebral Compression Fractures

    Science.gov (United States)

    ... and monitored to avoid putting pressure on the ribs that can cause new fractures. Surgical Procedures • When there is severe incapacitating pain • When healing is delayed or when bone fragments ...

  4. Paediatric talus fracture.

    LENUS (Irish Health Repository)

    Byrne, Ann-Maria

    2012-01-01

    Paediatric talus fractures are rare injuries resulting from axial loading of the talus against the anterior tibia with the foot in dorsiflexion. Skeletally immature bone is less brittle, with higher elastic resistance than adult bone, thus the paediatric talus can sustain higher forces before fractures occur. However, displaced paediatric talus fractures and those associated with high-energy trauma have been associated with complications including avascular necrosis, arthrosis, delayed union, neurapraxia and the need for revision surgery. The authors present the rare case of a talar neck fracture in a skeletally immature young girl, initially missed on radiological review. However, clinical suspicion on the part of the emergency physician, repeat examination and further radiographic imaging revealed this rare paediatric injury.

  5. Stress fractures in athletes

    International Nuclear Information System (INIS)

    Kirschberger, R.; Henning, A.; Graff, K.H.

    1984-01-01

    The early exclusion of the presence of a stress fracture may be decisive for the success of an athlete. Scintigraphy with a bone-seeking radiopharmaceutical is suitable for the early detection of stress lesions. Of 30 athletes, fractures were demonstrated in 17 whereas in 6 they were excluded. We found most fractures in the tarsal bones such as os naviculare pedis, ossa cuneiformia and talus. The type of sport engaged in appears to be an important factor in determining the location of the fracture. Scintiphotos were taken in several views using region of interest techniques and two phase-scintigraphy. This method is considered to be useful for localization and follow-up of skeletal stress lesions as well as for differential diagnosis. (orig.) [de

  6. Stress fractures in athletes

    Energy Technology Data Exchange (ETDEWEB)

    Kirschberger, R; Henning, A; Graff, K H

    1984-12-01

    The early exclusion of the presence of a stress fracture may be decisive for the success of an athlete. Scintigraphy with a bone-seeking radiopharmaceutical is suitable for the early detection of stress lesions. Of 30 athletes, fractures were demonstrated in 17 whereas in 6 they were excluded. We found most fractures in the tarsal bones such as os naviculare pedis, ossa cuneiformia and talus. The type of sport engaged in appears to be an important factor in determining the location of the fracture. Scintiphotos were taken in several views using region of interest techniques and two phase-scintigraphy. This method is considered to be useful for localization and follow-up of skeletal stress lesions as well as for differential diagnosis.

  7. Fatigue and insufficiency fractures

    International Nuclear Information System (INIS)

    Lodwick, G.S.; Rosenthal, D.I.; Kattapuram, S.V.; Hudson, T.M.

    1987-01-01

    The incidence of stress fracture is increasing. In our younger society this is due largely to a preocupation with physical conditioning, but in our elderly population it is due to improved recognition and better methods of detection and diagnosis. Stress fracture of the elderly is an insufficiency fracture which occurs in the spine, the pelvis, the sacrum and other bones afflicted with disorders which cause osteopenia. Stress fracture is frequently misdiagnosed as a malignant lesion of bone resulting in biopsy. Scintiscanning provides the greatest frequency of detection, while computed tomography often provides the definitive diagnosis. With increased interest and experience a better insight into the disease has been achieved, and what was once thought of as a simple manifestation of mechanical stress is now known to be an orderly, complex pattern of physiological changes in bone which conform to a model by Frost. The diffuse nature of these changes can be recognized by scintigraphy, radiography and magnetic resonance imaging. 27 refs.; 8 figs

  8. Ontology of fractures

    Science.gov (United States)

    Zhong, Jian; Aydina, Atilla; McGuinness, Deborah L.

    2009-03-01

    Fractures are fundamental structures in the Earth's crust and they can impact many societal and industrial activities including oil and gas exploration and production, aquifer management, CO 2 sequestration, waste isolation, the stabilization of engineering structures, and assessing natural hazards (earthquakes, volcanoes, and landslides). Therefore, an ontology which organizes the concepts of fractures could help facilitate a sound education within, and communication among, the highly diverse professional and academic community interested in the problems cited above. We developed a process-based ontology that makes explicit specifications about fractures, their properties, and the deformation mechanisms which lead to their formation and evolution. Our ontology emphasizes the relationships among concepts such as the factors that influence the mechanism(s) responsible for the formation and evolution of specific fracture types. Our ontology is a valuable resource with a potential to applications in a number of fields utilizing recent advances in Information Technology, specifically for digital data and information in computers, grids, and Web services.

  9. Hydrologic mechanisms governing fluid flow in partially saturated, fractured, porous tuff at Yucca Mountain

    International Nuclear Information System (INIS)

    Wang, J.S.Y.; Narasimhan, T.N.

    1984-10-01

    In contrast to the saturated zone where fluid moves rapidly along fractures, the fractures (with apertures large relative to the size of matrix pores) will desaturate first during drainage process and the bulk of fluid flow would be through interconnected pores in the matrix. Within a partially drained fracture, the presence of a relatively continuous air phase will produce practically an infinite resistance to liquid flow in the direction parallel to the fracture. The residual liquid will be held by capillary force in regions around fracture contact areas where the apertures are small. Normal to the fracture surfaces, the drained portion of the fractures will reduce the effective area for liquid flow from one matrix block to another matrix block. A general statistical theory is constructed for flow along the fracture and for flow between the matrix blocks to the fractures under partially saturated conditions. Results are obtained from an aperture distribution model for fracture saturation, hydraulic conductivity, and effective matrix-fracture flow areas as functions of pressure. Drainage from a fractured tuff column is simulated. The parameters for the simulations are deduced from fracture surface characteristics, spacings and orientations based on core analyses, and from matrix characteristics curve based on laboratory measurements. From the cases simulated for the fractured, porous column with discrete vertical and horizontal fractures and porous matrix blocks explicitly taken into account, it is observed that the highly transient changes from fully saturated conditions to partially saturated conditions are extremely sensitive to the fracture properties. However, the quasi-steady changes of the fluid flow of a partially saturated, fractured, porous system could be approximately simulated without taking the fractures into account. 22 references, 16 figures

  10. Osteoporotic fractures in older adults

    OpenAIRE

    Colón-Emeric, Cathleen S.; Saag, Kenneth G.

    2006-01-01

    Osteoporotic fractures are emerging as a major public health problem in the aging population. Fractures result in increased morbidity, mortality and health expenditures. This article reviews current evidence for the management of common issues following osteoporotic fractures in older adults including: (1) thromboembolism prevention; (2) delirium prevention; (3) pain management; (4) rehabilitation; (5) assessing the cause of fracture; and (6) prevention of subsequent fractures. Areas for prac...

  11. Classical fracture mechanics methods

    International Nuclear Information System (INIS)

    Schwalbe, K.H.; Heerens, J.; Landes, J.D.

    2007-01-01

    Comprehensive Structural Integrity is a reference work which covers all activities involved in the assurance of structural integrity. It provides engineers and scientists with an unparalleled depth of knowledge in the disciplines involved. The new online Volume 11 is dedicated to the mechanical characteristics of materials. This paper contains the chapter 11.02 of this volume and is structured as follows: Test techniques; Analysis; Fracture behavior; Fracture toughness tests for nonmetals

  12. A Fracture Decoupling Experiment

    Science.gov (United States)

    Stroujkova, A. F.; Bonner, J. L.; Leidig, M.; Ferris, A. N.; Kim, W.; Carnevale, M.; Rath, T.; Lewkowicz, J.

    2012-12-01

    Multiple observations made at the Semipalatinsk Test Site suggest that conducting nuclear tests in the fracture zones left by previous explosions results in decreased seismic amplitudes for the second nuclear tests (or "repeat shots"). Decreased seismic amplitudes reduce both the probability of detection and the seismically estimated yield of a "repeat shot". In order to define the physical mechanism responsible for the amplitude reduction and to quantify the degree of the amplitude reduction in fractured rocks, Weston Geophysical Corp., in collaboration with Columbia University's Lamont Doherty Earth Observatory, conducted a multi-phase Fracture Decoupling Experiment (FDE) in central New Hampshire. The FDE involved conducting explosions of various yields in the damage/fracture zones of previously detonated explosions. In order to quantify rock damage after the blasts we performed well logging and seismic cross-hole tomography studies of the source region. Significant seismic velocity reduction was observed around the source regions after the initial explosions. Seismic waves produced by the explosions were recorded at near-source and local seismic networks, as well as several regional stations throughout northern New England. Our analysis confirms frequency dependent seismic amplitude reduction for the repeat shots compared to the explosions in un-fractured rocks. The amplitude reduction is caused by pore closing and/or by frictional losses within the fractured media.

  13. FRACTURING FLUID CHARACTERIZATION FACILITY

    Energy Technology Data Exchange (ETDEWEB)

    Subhash Shah

    2000-08-01

    Hydraulic fracturing technology has been successfully applied for well stimulation of low and high permeability reservoirs for numerous years. Treatment optimization and improved economics have always been the key to the success and it is more so when the reservoirs under consideration are marginal. Fluids are widely used for the stimulation of wells. The Fracturing Fluid Characterization Facility (FFCF) has been established to provide the accurate prediction of the behavior of complex fracturing fluids under downhole conditions. The primary focus of the facility is to provide valuable insight into the various mechanisms that govern the flow of fracturing fluids and slurries through hydraulically created fractures. During the time between September 30, 1992, and March 31, 2000, the research efforts were devoted to the areas of fluid rheology, proppant transport, proppant flowback, dynamic fluid loss, perforation pressure losses, and frictional pressure losses. In this regard, a unique above-the-ground fracture simulator was designed and constructed at the FFCF, labeled ''The High Pressure Simulator'' (HPS). The FFCF is now available to industry for characterizing and understanding the behavior of complex fluid systems. To better reflect and encompass the broad spectrum of the petroleum industry, the FFCF now operates under a new name of ''The Well Construction Technology Center'' (WCTC). This report documents the summary of the activities performed during 1992-2000 at the FFCF.

  14. Reactive silica transport in fractured porous media: Analytical solutions for a system of parallel fractures

    Science.gov (United States)

    Yang, Jianwen

    2012-04-01

    A general analytical solution is derived by using the Laplace transformation to describe transient reactive silica transport in a conceptualized 2-D system involving a set of parallel fractures embedded in an impermeable host rock matrix, taking into account of hydrodynamic dispersion and advection of silica transport along the fractures, molecular diffusion from each fracture to the intervening rock matrix, and dissolution of quartz. A special analytical solution is also developed by ignoring the longitudinal hydrodynamic dispersion term but remaining other conditions the same. The general and special solutions are in the form of a double infinite integral and a single infinite integral, respectively, and can be evaluated using Gauss-Legendre quadrature technique. A simple criterion is developed to determine under what conditions the general analytical solution can be approximated by the special analytical solution. It is proved analytically that the general solution always lags behind the special solution, unless a dimensionless parameter is less than a critical value. Several illustrative calculations are undertaken to demonstrate the effect of fracture spacing, fracture aperture and fluid flow rate on silica transport. The analytical solutions developed here can serve as a benchmark to validate numerical models that simulate reactive mass transport in fractured porous media.

  15. 2014 New Trends in Fatigue and Fracture Conference

    CERN Document Server

    Milovic, Ljubica

    2017-01-01

    This book is a compilation of selected papers from the 2014 New Trends in Fatigue and Fracture (NT2F14) Conference, which was held in Belgrade, Serbia. This prestigious conference brought together delegates from around the globe to discuss how to characterize, predict and analyze the fatigue and fracture of engineering materials, components, and structures using theoretical, experimental, numerical and practical approaches. It highlights some important new trends in fracture mechanics presented at the conference, such as: • two-parameter fracture mechanics, arising from the coupling of fracture toughness and stress constraints • high-performance steel for gas and oil transportation and production (pressure vessels and boilers) • safety and reliability of welded joints This book includes 12 contributions from well-known international scientists and a special tribute dedicated to the scientific contributions of Stojan Sedmark, who passed away in 2014.

  16. Modeling of flow through fractured tuff at Fran Ridge

    International Nuclear Information System (INIS)

    Eaton, R.R.; Ho, C.K.; Glass, R.J.; Nicholl, M.J.; Arnold, B.W.

    1996-01-01

    Numerical studies have modeled an infiltration experiment at Fran Ridge, using the TOUGH2 code, to aid in the selection of computational models for waste repository performance assessment. This study investigates the capabilities of TOUGH2 to simulate transient flows through highly fractured tuff, and provides a possible means of calibrating hydrologic parameters such as effective fracture aperture and fracture-matrix connectivity. Two distinctly different conceptual models were used in the TOUGH2 code, the dual permeability model and the equivalent continuum model. The field experiments involved the infiltration of dyed ponded water in highly fractured tuff. The infiltration observed in the experiment was subsequently modeled using Fran Ridge fracture frequencies, obtained during post-experiment site excavation. Comparison of the TOUGH2 results obtained using the two conceptual models gives insight into their relative strengths and weaknesses

  17. Thermal fracture and pump limit of Nd: glass

    International Nuclear Information System (INIS)

    Wang Mingzhe; Ma Wen; Tan Jichun; Zhang Yongliang; Li Mingzhong; Jing Feng

    2011-01-01

    Based on published fracture experiments and 3D transient finite-element analyses, and taking the first principal stress as the criterion and the Griffith crack theory to determine the critical fracture stress, a Weibull statistical model is established to predict the fracture possibility of Nd: glass with certain pump parameters. Other issues which limit the pump power are also presented. The results show that the fracture limit of laser medium depends on the optical polishing technology. For a short pulse and high energy Nd: glass laser, taking America's polishing technology in the 1990s as reference,the pump saturation limits the pump power to 18 kW/cm 2 when the repetition rate is lower than 1 Hz, while the thermal fracture limits the pump power when the repetition rate is higher than 10 Hz. (authors)

  18. Parameter Estimation

    DEFF Research Database (Denmark)

    Sales-Cruz, Mauricio; Heitzig, Martina; Cameron, Ian

    2011-01-01

    of optimisation techniques coupled with dynamic solution of the underlying model. Linear and nonlinear approaches to parameter estimation are investigated. There is also the application of maximum likelihood principles in the estimation of parameters, as well as the use of orthogonal collocation to generate a set......In this chapter the importance of parameter estimation in model development is illustrated through various applications related to reaction systems. In particular, rate constants in a reaction system are obtained through parameter estimation methods. These approaches often require the application...... of algebraic equations as the basis for parameter estimation.These approaches are illustrated using estimations of kinetic constants from reaction system models....

  19. Fractures of the Jaw and Midface

    Science.gov (United States)

    ... switch to the Professional version Home Injuries and Poisoning Facial Injuries Fractures of the Jaw and Midface Symptoms Diagnosis Treatment Treatment of mandible fractures Treatment of maxillary fractures ...

  20. The Criteria for the Selection of Wells for Hydraulic Fracturing

    Directory of Open Access Journals (Sweden)

    O.V. Salimov

    2017-12-01

    Full Text Available Various methods of selection of wells for hydraulic fracturing are analyzed. It is established that all methods can be divided into three large groups: criteria in the table form of boundary values of parameters, statistical methods of pattern recognition, methods of engineering calculation. The complication or use of additional parameters only leads to a reduction in the number of wells at which hydraulic fracturing is possible. It is shown that the use of reservoir properties of rocks, which are already used by hydraulic fracturing simulators, is not practicable as selection criteria. It is required to include in the selection criteria only those additional factors on which the effectiveness of hydraulic fracturing depends directly.

  1. Probabilistic Risk Assessment for Astronaut Post Flight Bone Fracture

    Science.gov (United States)

    Lewandowski, Beth; Myers, Jerry; Licata, Angelo

    2015-01-01

    Introduction: Space flight potentially reduces the loading that bone can resist before fracture. This reduction in bone integrity may result from a combination of factors, the most common reported as reduction in astronaut BMD. Although evaluating the condition of bones continues to be a critical aspect of understanding space flight fracture risk, defining the loading regime, whether on earth, in microgravity, or in reduced gravity on a planetary surface, remains a significant component of estimating the fracture risks to astronauts. This presentation summarizes the concepts, development, and application of NASA's Bone Fracture Risk Module (BFxRM) to understanding pre-, post, and in mission astronaut bone fracture risk. The overview includes an assessment of contributing factors utilized in the BFxRM and illustrates how new information, such as biomechanics of space suit design or better understanding of post flight activities may influence astronaut fracture risk. Opportunities for the bone mineral research community to contribute to future model development are also discussed. Methods: To investigate the conditions in which spaceflight induced changes to bone plays a critical role in post-flight fracture probability, we implement a modified version of the NASA Bone Fracture Risk Model (BFxRM). Modifications included incorporation of variations in physiological characteristics, post-flight recovery rate, and variations in lateral fall conditions within the probabilistic simulation parameter space. The modeled fracture probability estimates for different loading scenarios at preflight and at 0 and 365 days post-flight time periods are compared. Results: For simple lateral side falls, mean post-flight fracture probability is elevated over mean preflight fracture probability due to spaceflight induced BMD loss and is not fully recovered at 365 days post-flight. In the case of more energetic falls, such as from elevated heights or with the addition of lateral movement

  2. In vitro compressive fracture resistance of human maxillary first premolar with different mesial occlusal distal cavity

    Directory of Open Access Journals (Sweden)

    Wen-Chou Wu

    2014-09-01

    Conclusion: A bonded ceramic restoration restores the fracture load of a tooth comparable to an intact tooth independent of the examined design parameters, whereas the fracture loads of composite-resin-restored teeth were dependent on cavity widths. Cavity pulpal floor depth is not a significant factor of cusp fracture resistance in a tooth restored with either a ceramic inlay or composite resin.

  3. Radiological classification of mandibular fractures

    International Nuclear Information System (INIS)

    Mihailova, H.

    2009-01-01

    Mandibular fractures present the biggest part (up to 97%) of the facial bone fractures. Method of choice for diagnosing of mandibular fractures is conventional radiography. The aim of the issue is to present an unified radiological classification of mandibular fractures for the clinical practice. This classification includes only those clinical symptoms of mandibular fracture which could be radiologically objectified: exact anatomical localization (F1-F6), teeth in fracture line (Ta,Tb), grade of dislocation (D I, D II), occlusal disturbances (O(+), O(-)). Radiological symptoms expressed by letter and number symbols are systematized in a formula - FTDO of mandibular fractures similar to TNM formula for tumours. FTDO formula expresses radiological diagnose of each mandibular fracture but it doesn't include neither the site (left or right) of the fracture, nor the kind and number of fractures. In order to express topography and number of fractures the radiological formula is transformed into a decimal fraction. The symbols (FTD) of right mandible fracture are written in the numerator and those of the left site - in the denominator. For double and multiple fractures between the symbols for each fracture we put '+'. Symbols for occlusal disturbances are put down opposite, the fractional line. So topographo-anatomical formula (FTD/FTD)xO is formed. In this way the whole radiological information for unilateral, bilateral, single or multiple fractures of the mandible is expressed. The information in the radiological topography anatomic formula, resp. from the unified topography-anatomic classification ensures a quick and exact X-ray diagnose of mandibular fracture. In this way contributes to get better, make easier and faster X-ray diagnostic process concerning mandibular fractures. And all these is a precondition for prevention of retardation of the diagnosis mandibular fracture. (author)

  4. Scale dependency of fractional flow dimension in a fractured formation

    Directory of Open Access Journals (Sweden)

    Y.-C. Chang

    2011-07-01

    Full Text Available The flow dimensions of fractured media were usually predefined before the determination of the hydraulic parameters from the analysis of field data in the past. However, it would be improper to make assumption about the flow geometry of fractured media before site characterization because the hydraulic structures and flow paths are complex in the fractured media. An appropriate way to investigate the hydrodynamic behavior of a fracture system is to determine the flow dimension and aquifer parameters simultaneously. The objective of this study is to analyze a set of field data obtained from four observation wells during an 11-day hydraulic test at Chingshui geothermal field (CGF in Taiwan in determining the hydrogeologic properties of the fractured formation. Based on the generalized radial flow (GRF model and the optimization scheme, simulated annealing, an approach is therefore developed for the data analyses. The GRF model allows the flow dimension to be integer or fractional. We found that the fractional flow dimension of CGF increases near linearly with the distance between the pumping well and observation well, i.e. the flow dimension of CGF exhibits scale-dependent phenomenon. This study provides insights into interpretation of fracture flow at CGF and gives a reference for characterizing the hydrogeologic properties of fractured media.

  5. Tracer dispersion in two-dimensional rough fractures.

    Science.gov (United States)

    Drazer, G; Koplik, J

    2001-05-01

    Tracer diffusion and hydrodynamic dispersion in two-dimensional fractures with self-affine roughness are studied by analytic and numerical methods. Numerical simulations were performed via the lattice-Boltzmann approach, using a boundary condition for tracer particles that improves the accuracy of the method. The reduction in the diffusive transport, due to the fractal geometry of the fracture surfaces, is analyzed for different fracture apertures. In the limit of small aperture fluctuations we derive the correction to the diffusive coefficient in terms of the tortuosity, which accounts for the irregular geometry of the fractures. Dispersion is studied when the two fracture surfaces are simply displaced normally to the mean fracture plane and when there is a lateral shift as well. Numerical results are analyzed using the Lambda parameter, related to convective transport within the fracture, and simple arguments based on lubrication approximation. At very low Péclet number, in the case where fracture surfaces are laterally shifted, we show using several different methods that convective transport reduces dispersion.

  6. Estimation of fracture roughness from the acoustic borehole televiewer image

    International Nuclear Information System (INIS)

    Bae, Dae Soek; Kim, Chun Soo; Kim, Kyung Soo; Park, Byung Yoon; Koh, Yong Kweon

    2000-12-01

    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 'FRAFA' 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

  7. Radionuclide migration in crystalline rock fractures

    International Nuclear Information System (INIS)

    Hoelttae, P.

    2002-01-01

    Crystalline rock has been considered as a host medium for the repository of high radioactive spent nuclear fuel in Finland. The geosphere will act as an ultimate barrier retarding the migration of radionuclides to the biosphere if they are released through the technical barriers. Radionuclide transport is assumed to take place along watercarrying fractures, and retardation will occur both in the fracture and within the rock matrix. To be able to predict the transport and retardation of radionuclides in rock fractures and rock matrices, it is essential to understand the different phenomena involved. Matrix diffusion has been indicated to be an important mechanism, which will retard the transport of radionuclides in rock fractures. Both dispersion and matrix diffusion are processes, which can have similar influences on solute breakthrough curves in fractured crystalline rock. In this work, the migration of radionuclides in crystalline rock fractures was studied by means of laboratory scale column methods. The purpose of the research was to gain a better understanding of various phenomena - particularly matrix diffusion - affecting the transport and retardation behaviour of radionuclides in fracture flow. Interaction between radionuclides and the rock matrix was measured in order to test the compatibility of experimental retardation parameters and transport models used in assessing the safety of underground repositories for spent nuclear fuel. Rock samples of mica gneiss and of unaltered, moderately altered and strongly altered tonalite represented different rock features and porosities offering the possibility to determine experimental boundary limit values for parameters describing both the transport and retardation of radionuclides and rock matrix properties. The dominant matrix diffusion behaviour was demonstrated in porous ceramic column and gas diffusion experiments. Demonstration of the effects of matrix diffusion in crystalline rock fracture succeeded for the

  8. Underground nuclear explosion effects in granite rock fracturing

    International Nuclear Information System (INIS)

    Derlich, S.

    1970-01-01

    On the Saharan nuclear test site in Hoggar granite, mechanical properties of the altered zones were studied by in situ and laboratory measurements. In situ methods of study are drillings, television, geophysical and permeability measurements. Fracturing is one of the most important nuclear explosion effects. Several altered zones were identified. There are: crushed zone, fractured zone and stressed zone. Collapse of crushed and fractured zone formed the chimney. The extent of each zone can be expressed in terms of yield and of characteristic parameters. Such results are of main interest for industrial uses of underground nuclear explosives in hard rock. (author)

  9. Underground nuclear explosion effects in granite rock fracturing

    Energy Technology Data Exchange (ETDEWEB)

    Derlich, S [Commissariat a l' Energie Atomique, Centre d' Etude de Bruyeres-le-Chatel (France)

    1970-05-01

    On the Saharan nuclear test site in Hoggar granite, mechanical properties of the altered zones were studied by in situ and laboratory measurements. In situ methods of study are drillings, television, geophysical and permeability measurements. Fracturing is one of the most important nuclear explosion effects. Several altered zones were identified. There are: crushed zone, fractured zone and stressed zone. Collapse of crushed and fractured zone formed the chimney. The extent of each zone can be expressed in terms of yield and of characteristic parameters. Such results are of main interest for industrial uses of underground nuclear explosives in hard rock. (author)

  10. The effect of specimen and flaw dimensions on fracture toughness

    International Nuclear Information System (INIS)

    Nevalainen, M.J.

    1997-06-01

    The effect of the specimen size and geometry on fracture toughness has been investigated both by experimental tests and computational analyses. The methods for constraint description, namely T-stress, Q-parameter and Small-Scale Yielding Correction (SSYC) have been compared and applied for various geometries. A statistical treatment for the specimen thickness effect on cleavage fracture toughness has been investigated. Elliptical surface cracks were compared with straight-thickness cracks and a method for crack shape correction was presented. Based on the results, the differences in apparent fracture toughness values obtained from various specimen configurations can be better understood and taken into account

  11. Fracture resistance enhancement of layered structures by multiple cracks

    DEFF Research Database (Denmark)

    Goutianos, Stergios; Sørensen, Bent F.

    2016-01-01

    A theoretical model is developed to test if the fracture resistance of a layered structure can be increased by introducing weak layers changing the cracking mechanism. An analytical model, based on the J integral, predicts a linear dependency between the number of cracks and the steady state...... fracture resistance. A finite element cohesive zone model, containing two cracking planes for simplicity, is used to check the theoretical model and its predictions. It is shown that for a wide range of cohesive law parameters, the numerical predictions agree well quantitatively with the theoretical model....... Thus, it is possible to enhance considerably the fracture resistance of a structure by adding weak layers....

  12. Computer model for ductile fracture

    International Nuclear Information System (INIS)

    Moran, B.; Reaugh, J. E.

    1979-01-01

    A computer model is described for predicting ductile fracture initiation and propagation. The computer fracture model is calibrated by simple and notched round-bar tension tests and a precracked compact tension test. The model is used to predict fracture initiation and propagation in a Charpy specimen and compare the results with experiments. The calibrated model provides a correlation between Charpy V-notch (CVN) fracture energy and any measure of fracture toughness, such as J/sub Ic/. A second simpler empirical correlation was obtained using the energy to initiate fracture in the Charpy specimen rather than total energy CVN, and compared the results with the empirical correlation of Rolfe and Novak

  13. Polymer liquids fracture like solids

    DEFF Research Database (Denmark)

    Huang, Qian; Hassager, Ole

    2017-01-01

    While fracture in brittle solids has been studied for centuries until today, there are few studies on fracture in polymer liquids. Recent developments in experimental techniques, especially the combination of controlled filament stretching rheometry and high speed imaging, have opened new windows...... into the detailed study of fracture processes for polymer liquids. High speed imaging shows that polymer liquids fracture like solids with initiation and propagation of an edge fracture. However, remarkable features such as highly reproducible critical stress, independent appearance of multiple fractures...

  14. Management of penile fractures

    International Nuclear Information System (INIS)

    Ghilan, Abdulelah M. M.; Al-Asbahi, Waleed A.; Alwan, Mohammed A.; Al-Khanbashi, Omar M.; Ghafour, Mohammed A.

    2008-01-01

    Objective was to present our experience with surgical and conservative management of penile fracture. This prospective study was carried out in the Urology and Nephrology Center, at Al-Thawra General and Teaching Hospital, Sana'a, Yemen from June 2003 to September 2007 and included 30 patients presenting with penile fracture. Diagnosis was made clinically in all our patients. Six patients with simple fracture were treated conservatively while 24 patients with more severe injuries were operated upon. Patient's age ranged from 24-52 years (mean 31.3 years) 46.7% of patients were under the age of 30 years and 56.7% were unmarried. Hard manipulation of the erect penis for example during masturbation was the most frequent mechanism of fracture in 53.3% of patients. Solitary tear was found in 22 patients and bilateral corporal tears associated with urethral injury were found in 2 patients. Corporal tears were saturated with synthetic absorbable sutures and urethral injury was repaired primarily. All operated patients described full erection with straight penis except 3 of the 8 patients who were managed by direct longitudinal incision, in whom mild curvature during erection was observed. The conservatively treated patients described satisfactory penile straightness and erection. The optimal functional and cosmetic results are achieved following immediate surgical repair of penis fracture. Good results can also be obtained in some selected patients with conservative management. (author)

  15. Stress fractures in athletes

    International Nuclear Information System (INIS)

    Steingruber, I.E.; Wolf, C.; Gruber, H.; Czermak, B.V.; Mallouhi, A.; Jaschke, W.; Gabriel, M.

    2002-01-01

    Stress fractures may pose a diagnostic dilemma for radiologists since they are sometimes difficult to demonstrate on plain films and may simulate a tumour. They were first described in military personnel and professional athletes. Recently, there is an increasing incidence in the general population due to increasing sportive activities. Stress fractures occur most often in the lower extremities, especially in the tibia, the tarsal bone, the metatarsal bone, the femur and the fibula. In the upper extremities, they are commonly found in the humerus, the radius and the ulna. Some fractures of the lower extremities appear to be specific for particular sports, for example, fractures of the tibia affect mostly distance runners. Whereas stress fractures of the upper extremities are generally associated with upper limb-dominated sports. A correct diagnosis requires a careful clinical evaluation. The initial plain radiography may be normal. Further radiological evaluation could be performed by means of computerised tomography, magnetic resonance imaging and bone scanning. The latter two techniques are especially helpful for establishing a correct initial diagnosis. (orig.) [de

  16. 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

  17. Mass transport in fracture media: impact of the random function model assumed for fractures conductivity

    International Nuclear Information System (INIS)

    Capilla, J. E.; Rodrigo, J.; Gomez Hernandez, J. J.

    2003-01-01

    Characterizing the uncertainty of flow and mass transport models requires the definition of stochastic models to describe hydrodynamic parameters. Porosity and hydraulic conductivity (K) are two of these parameters that exhibit a high degree of spatial variability. K is usually the parameter whose variability influence to a more extended degree solutes movement. In fracture media, it is critical to properly characterize K in the most altered zones where flow and solutes migration tends to be concentrated. However, K measurements use to be scarce and sparse. This fact calls to consider stochastic models that allow quantifying the uncertainty of flow and mass transport predictions. This paper presents a convective transport problem solved in a 3D block of fractured crystalline rock. the case study is defined based on data from a real geological formation. As the scarcity of K data in fractures does not allow supporting classical multi Gaussian assumptions for K in fractures, the non multi Gaussian hypothesis has been explored, comparing mass transport results for alternative Gaussian and non-Gaussian assumptions. The latter hypothesis allows reproducing high spatial connectivity for extreme values of K. This feature is present in nature, might lead to reproduce faster solute pathways, and therefore should be modeled in order to obtain reasonably safe prediction of contaminants migration in a geological formation. The results obtained for the two alternative hypotheses show a remarkable impact of the K random function model in solutes movement. (Author) 9 refs

  18. MR imaging of scaphoid fractures

    DEFF Research Database (Denmark)

    Meincke, Louise; Radev, Dimitar; Eriksen, Rie Østbjerg

    2017-01-01

    the importance of early MRI and hereby predict bone bruise with the help of fat suppression sequence; however, only a limited selection articles compares various fat suppression techniques. The purpose of this prospective study was to compare the short tau inversion recovery (STIR) and T2 fat saturation (FAT SAT......) sequences, sectional directed along the scaphoid bone axis. In relation to background fat intensity suppression, this study sought the sequence that best evaluated posttraumatic bone marrow edema (bone bruise) on scaphoid injury musculoskeletal magnetic resonance imaging (MRI, 1.5 T extremity scanner......). Materials and methods: Two hundred and fifty-one patients with relevant trauma and positive clinical test for scaphoid bone fractures, exceeding no more than 14 days, underwent MRI examinations. A fast STIR and T2 FAT SAT fast spin echo sequence (FSE) were obtained using a comparable parameter setting (scan...

  19. Prediction of fracture initiation in square cup drawing of DP980 using an anisotropic ductile fracture criterion

    Science.gov (United States)

    Park, N.; Huh, H.; Yoon, J. W.

    2017-09-01

    This paper deals with the prediction of fracture initiation in square cup drawing of DP980 steel sheet with the thickness of 1.2 mm. In an attempt to consider the influence of material anisotropy on the fracture initiation, an uncoupled anisotropic ductile fracture criterion is developed based on the Lou—Huh ductile fracture criterion. Tensile tests are carried out at different loading directions of 0°, 45°, and 90° to the rolling direction of the sheet using various specimen geometries including pure shear, dog-bone, and flat grooved specimens so as to calibrate the parameters of the proposed fracture criterion. Equivalent plastic strain distribution on the specimen surface is computed using Digital Image Correlation (DIC) method until surface crack initiates. The proposed fracture criterion is implemented into the commercial finite element code ABAQUS/Explicit by developing the Vectorized User-defined MATerial (VUMAT) subroutine which features the non-associated flow rule. Simulation results of the square cup drawing test clearly show that the proposed fracture criterion is capable of predicting the fracture initiation with sufficient accuracy considering the material anisotropy.

  20. Quantitative MR imaging in fracture dating--Initial results.

    Science.gov (United States)

    Baron, Katharina; Neumayer, Bernhard; Widek, Thomas; Schick, Fritz; Scheicher, Sylvia; Hassler, Eva; Scheurer, Eva

    2016-04-01

    For exact age determinations of bone fractures in a forensic context (e.g. in cases of child abuse) improved knowledge of the time course of the healing process and use of non-invasive modern imaging technology is of high importance. To date, fracture dating is based on radiographic methods by determining the callus status and thereby relying on an expert's experience. As a novel approach, this study aims to investigate the applicability of magnetic resonance imaging (MRI) for bone fracture dating by systematically investigating time-resolved changes in quantitative MR characteristics after a fracture event. Prior to investigating fracture healing in children, adults were examined for this study in order to test the methodology for this application. Altogether, 31 MR examinations in 17 subjects (♀: 11 ♂: 6; median age 34 ± 15 y, scanned 1-5 times over a period of up to 200 days after the fracture event) were performed on a clinical 3T MR scanner (TimTrio, Siemens AG, Germany). All subjects were treated conservatively for a fracture in either a long bone or in the collar bone. Both, qualitative and quantitative MR measurements were performed in all subjects. MR sequences for a quantitative measurement of relaxation times T1 and T2 in the fracture gap and musculature were applied. Maps of quantitative MR parameters T1, T2, and magnetisation transfer ratio (MTR) were calculated and evaluated by investigating changes over time in the fractured area by defined ROIs. Additionally, muscle areas were examined as reference regions to validate this approach. Quantitative evaluation of 23 MR data sets (12 test subjects, ♀: 7 ♂: 5) showed an initial peak in T1 values in the fractured area (T1=1895 ± 607 ms), which decreased over time to a value of 1094 ± 182 ms (200 days after the fracture event). T2 values also peaked for early-stage fractures (T2=115 ± 80 ms) and decreased to 73 ± 33 ms within 21 days after the fracture event. After that time point, no

  1. 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

  2. Influence of bone mineral density and hip geometry on the different types of hip fracture.

    Science.gov (United States)

    Li, Yizhong; Lin, Jinkuang; Cai, Siqing; Yan, Lisheng; Pan, Yuancheng; Yao, Xuedong; Zhuang, Huafeng; Wang, Peiwen; Zeng, Yanjun

    2016-01-01

    The aim of this study was to assess the influence of bone mineral density and hip geometry on the fragility fracture of femoral neck and trochanteric region. There were 95 menopausal females of age ≥ 50 years with fragility fracture of hip, including 55 cases of femoral neck fracture and 40 cases of trochanteric fracture. Another 63 non-fractured females with normal bone mineral density (BMD) were chosen as control. BMD, hip axis length, neck-shaft angle and structural parameters including cross surface area, cortical thickness and buckling ratio were detected and compared. Compared with control group, the patients with femoral neck fracture or trochanteric fractures had significantly lower BMD of femoral neck, as well as lower cross surface area and cortical thickness and higher buckling ratio in femoral neck and trochanteric region. There were no significant differences of BMD and structural parameters in the femoral neck fracture group and intertrochanteric fracture group. Hip axis length and neck-shaft angle were not significantly different among three groups. The significant changes of BMD and proximal femur geometry were present in the fragility fracture of femoral neck and trochanteric region. The different types of hip fractures cannot be explained by these changes.

  3. Influence of bone mineral density and hip geometry on the different types of hip fracture

    Directory of Open Access Journals (Sweden)

    Yizhong Li

    2016-01-01

    Full Text Available The aim of this study was to assess the influence of bone mineral density and hip geometry on the fragility fracture of femoral neck and trochanteric region. There were 95 menopausal females of age ≥ 50 years with fragility fracture of hip, including 55 cases of femoral neck fracture and 40 cases of trochanteric fracture. Another 63 non-fractured females with normal bone mineral density (BMD were chosen as control. BMD, hip axis length, neck-shaft angle and structural parameters including cross surface area, cortical thickness and buckling ratio were detected and compared. Compared with control group, the patients with femoral neck fracture or trochanteric fractures had significantly lower BMD of femoral neck, as well as lower cross surface area and cortical thickness and higher buckling ratio in femoral neck and trochanteric region. There were no significant differences of BMD and structural parameters in the femoral neck fracture group and intertrochanteric fracture group. Hip axis length and neck-shaft angle were not significantly different among three groups. The significant changes of BMD and proximal femur geometry were present in the fragility fracture of femoral neck and trochanteric region. The different types of hip fractures cannot be explained by these changes.

  4. Transstyloid, transscaphoid, transcapitate fracture: a variant of scaphocapitate fractures.

    LENUS (Irish Health Repository)

    Burke, Neil G

    2014-01-01

    Transstyloid, transscaphoid, transcapitate fractures are uncommon. We report the case of a 28-year-old man who sustained this fracture following direct trauma. The patient was successfully treated by open reduction internal fixation of the scaphoid and proximal capitate fragment, with a good clinical outcome at 1-year follow-up. This pattern is a new variant of scaphocapitate fracture as involves a fracture of the radial styloid as well.

  5. Rib fractures after percutaneous radiofrequency and microwave ablation of lung tumors: incidence and relevance.

    Science.gov (United States)

    Alexander, Erica S; Hankins, Carol A; Machan, Jason T; Healey, Terrance T; Dupuy, Damian E

    2013-03-01

    To retrospectively identify the incidence and probable risk factors for rib fractures after percutaneous radiofrequency ablation (RFA) and microwave ablation (MWA) of neoplasms in the lung and to identify complications related to these fractures. Institutional review board approval was obtained for this HIPAA-compliant retrospective study. Study population was 163 patients treated with MWA and/or RFA for 195 lung neoplasms between February 2004 and April 2010. Follow-up computed tomographic images of at least 3 months were retrospectively reviewed by board-certified radiologists to determine the presence of rib fractures. Generalized estimating equations were performed to assess the effect that patient demographics, tumor characteristics, treatment parameters, and ablation zone characteristics had on development of rib fractures. Kaplan-Meier curve was used to estimate patients' probability of rib fracture after ablation as a function of time. Clinical parameters (ie, pain in ribs or chest, organ damage caused by fractured rib) were evaluated for patients with confirmed fracture. Rib fractures in proximity to the ablation zone were found in 13.5% (22 of 163) of patients. Estimated probability of fracture was 9% at 1 year and 22% at 3 years. Women were more likely than were men to develop fracture after ablation (P = .041). Patients with tumors closer to the chest wall were more likely to develop fracture (P = .0009), as were patients with ablation zones that involved visceral pleura (P = .039). No patients with rib fractures that were apparently induced by RFA and MWA had organ injury or damage related to fracture, and 9.1% (2 of 22) of patients reported mild pain. Rib fractures were present in 13.5% of patients after percutaneous RFA and MWA of lung neoplasms. Patients who had ablations performed close to the chest wall should be monitored for rib fractures.

  6. DEM Particle Fracture Model

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Boning [Univ. of Colorado, Boulder, CO (United States); Herbold, Eric B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Homel, Michael A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Regueiro, Richard A. [Univ. of Colorado, Boulder, CO (United States)

    2015-12-01

    An adaptive particle fracture model in poly-ellipsoidal Discrete Element Method is developed. The poly-ellipsoidal particle will break into several sub-poly-ellipsoids by Hoek-Brown fracture criterion based on continuum stress and the maximum tensile stress in contacts. Also Weibull theory is introduced to consider the statistics and size effects on particle strength. Finally, high strain-rate split Hopkinson pressure bar experiment of silica sand is simulated using this newly developed model. Comparisons with experiments show that our particle fracture model can capture the mechanical behavior of this experiment very well, both in stress-strain response and particle size redistribution. The effects of density and packings o the samples are also studied in numerical examples.

  7. [Distal clavicle fracture].

    Science.gov (United States)

    Seppel, G; Lenich, A; Imhoff, A B

    2014-06-01

    Reposition and fixation of unstable distal clavicle fractures with a low profile locking plate (Acumed, Hempshire, UK) in conjunction with a button/suture augmentation cerclage (DogBone/FibreTape, Arthrex, Naples, FL, USA). Unstable fractures of the distal clavicle (Jäger and Breitner IIA) in adults. Unstable fractures of the distal clavicle (Jäger and Breitner IV) in children. Distal clavicle fractures (Jäger and Breitner I, IIB or III) with marked dislocation, injury of nerves and vessels, or high functional demand. Patients in poor general condition. Fractures of the distal clavicle (Jäger and Breitner I, IIB or III) without marked dislocation or vertical instability. Local soft-tissue infection. Combination procedure: Initially the lateral part of the clavicle is exposed by a 4 cm skin incision. After reduction of the fracture, stabilization is performed with a low profile locking distal clavicle plate. Using a special guiding device, a transclavicular-transcoracoidal hole is drilled under arthroscopic view. Additional vertical stabilization is arthroscopically achieved by shuttling the DogBone/FibreTape cerclage from the lateral portal cranially through the clavicular plate. The two ends of the FibreTape cerclage are brought cranially via adjacent holes of the locking plate while the DogBone button is placed under the coracoid process. Thus, plate bridging is achieved. Finally reduction is performed and the cerclage is secured by surgical knotting. Use of an arm sling for 6 weeks. Due to the fact that the described technique is a relatively new procedure, long-term results are lacking. In the short term, patients postoperatively report high subjective satisfaction without persistent pain.

  8. Foal Fractures: Osteochondral Fragmentation, Proximal Sesamoid Bone Fractures/Sesamoiditis, and Distal Phalanx Fractures.

    Science.gov (United States)

    Reesink, Heidi L

    2017-08-01

    Foals are susceptible to many of the same types of fractures as adult horses, often secondary to external sources of trauma. In addition, some types of fractures are specific to foals and occur routinely in horses under 1 year of age. These foal-specific fractures may be due to the unique musculoskeletal properties of the developing animal and may present with distinct clinical signs. Treatment plans and prognoses are tailored specifically to young animals. Common fractures not affecting the long bones in foals are discussed in this article, including osteochondral fragmentation, proximal sesamoid bone fractures/sesamoiditis, and distal phalanx fractures. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Hydraulic Fracturing and the Environment

    Science.gov (United States)

    Ayatollahy Tafti, T.; Aminzadeh, F.; Jafarpour, B.; de Barros, F.

    2013-12-01

    In this presentation, we highlight two key environmental concerns of hydraulic fracturing (HF), namely induced seismicity and groundwater contamination (GC). We examine the induced seismicity (IS) associated with different subsurface fluid injection and production (SFIP) operations and the key operational parameters of SFIP impacting it. In addition we review the key potential sources for possible water contamination. Both in the case of IS and GC we propose modeling and data analysis methods to quantify the risk factors to be used for monitoring and risk reduction. SFIP include presents a risk in hydraulic fracturing, waste water injection, enhanced oil recovery as well as geothermal energy operations. Although a recent report (NRC 2012) documents that HF is not responsible for most of the induced seismicities, we primarily focus on HF here. We look into vaious operational parameters such as volume and rate of water injection, the direction of the well versus the natural fracture network, the depth of the target and the local stress field and fault system, as well as other geological features. The latter would determine the potential for triggering tectonic related events by small induced seismicity events. We provide the building blocks for IS risk assessment and monitoring. The system we propose will involve adequate layers of complexity based on mapped seismic attributes as well as results from ANN and probabilistic predictive modeling workflows. This leads to a set of guidelines which further defines 'safe operating conditions' and 'safe operating zones' which will be a valuable reference for future SFIP operations. We also illustrate how HF can lead to groundwater aquifer contamination. The source of aquifer contamination can be the hydrocarbon gas or the chemicals used in the injected liquid in the formation. We explore possible pathways of contamination within and discuss the likelihood of contamination from each source. Many of the chemical compounds used

  10. Fractured Petroleum Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Firoozabadi, Dr. Abbas

    2000-01-18

    In this report the results of experiments of water injection in fractured porous media comprising a number of water-wet matrix blocks are reported for the first time. The blocks experience an advancing fracture-water level (FWL). Immersion-type experiments are performed for comparison; the dominant recovery mechanism changed from co-current to counter-current imbibition when the boundary conditions changed from advancing FWL to immersion-type. Single block experiments of co-current and counter-current imbibition was performed and co-current imbibition leads to more efficient recovery was found.

  11. Role of geomechanically grown fractures on dispersive transport in heterogeneous geological formations

    KAUST Repository

    Nick, H. M.

    2011-11-04

    A second order in space accurate implicit scheme for time-dependent advection-dispersion equations and a discrete fracture propagation model are employed to model solute transport in porous media. We study the impact of the fractures on mass transport and dispersion. To model flow and transport, pressure and transport equations are integrated using a finite-element, node-centered finite-volume approach. Fracture geometries are incrementally developed from a random distributions of material flaws using an adoptive geomechanical finite-element model that also produces fracture aperture distributions. This quasistatic propagation assumes a linear elastic rock matrix, and crack propagation is governed by a subcritical crack growth failure criterion. Fracture propagation, intersection, and closure are handled geometrically. The flow and transport simulations are separately conducted for a range of fracture densities that are generated by the geomechanical finite-element model. These computations show that the most influential parameters for solute transport in fractured porous media are as follows: fracture density and fracture-matrix flux ratio that is influenced by matrix permeability. Using an equivalent fracture aperture size, computed on the basis of equivalent permeability of the system, we also obtain an acceptable prediction of the macrodispersion of poorly interconnected fracture networks. The results hold for fractures at relatively low density. © 2011 American Physical Society.

  12. Role of geomechanically grown fractures on dispersive transport in heterogeneous geological formations

    KAUST Repository

    Nick, H. M.; Paluszny, A.; Blunt, M. J.; Matthai, S. K.

    2011-01-01

    A second order in space accurate implicit scheme for time-dependent advection-dispersion equations and a discrete fracture propagation model are employed to model solute transport in porous media. We study the impact of the fractures on mass transport and dispersion. To model flow and transport, pressure and transport equations are integrated using a finite-element, node-centered finite-volume approach. Fracture geometries are incrementally developed from a random distributions of material flaws using an adoptive geomechanical finite-element model that also produces fracture aperture distributions. This quasistatic propagation assumes a linear elastic rock matrix, and crack propagation is governed by a subcritical crack growth failure criterion. Fracture propagation, intersection, and closure are handled geometrically. The flow and transport simulations are separately conducted for a range of fracture densities that are generated by the geomechanical finite-element model. These computations show that the most influential parameters for solute transport in fractured porous media are as follows: fracture density and fracture-matrix flux ratio that is influenced by matrix permeability. Using an equivalent fracture aperture size, computed on the basis of equivalent permeability of the system, we also obtain an acceptable prediction of the macrodispersion of poorly interconnected fracture networks. The results hold for fractures at relatively low density. © 2011 American Physical Society.

  13. 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.

  14. Dynamic fracture characterization of material

    International Nuclear Information System (INIS)

    Kobayashi, A.S.; Emery, A.F.; Liaw, B.M.

    1981-01-01

    The influences of a wide range of material properties, i.e. of A533B steel, a silicon nitride ceramic and a Homalite-100 photoelastic polymer, as well as the influences of the specimen sizes on the dynamic fracture response of fracture specimens are presented in this paper. The results of a numerical study show that the dynamic fracture responses of these fracture specimens of proportional dimensions were indistinguishable provided the normalized dynamic fracture toughness versus normalized crack velocity relations of the three materials coincide. The limited results suggest that should the normalized dynamic fracture toughness versus normalized crack velocity relations between prototype and model materials coincide, then dynamic fracture experiments on scaled models can be used to infer the dynamic fracture response of the prototype. (orig./HP)

  15. 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.

  16. Flexible fixation and fracture healing

    DEFF Research Database (Denmark)

    Schmal, Hagen; Strohm, Peter C; Jaeger, Martin

    2011-01-01

    , noncomminuted fractures. External fixation uses external bars for stabilization, whereas internal fixation is realized by subcutaneous placement of locking plates. Both of these "biologic" osteosynthesis methods allow a minimally invasive approach and do not compromise fracture hematoma and periosteal blood...

  17. Gene Therapy for Fracture Repair

    National Research Council Canada - National Science Library

    Lau, William

    2005-01-01

    .... We have identified a murine leukemia virus (MLV) vector that provides robust transgene expression in fracture tissues, and applied it to the rat femur fracture model to express therapeutic transgenes...

  18. 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.)

  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. Correlation of Hip Fracture with Other Fracture Types: Toward a Rational Composite Hip Fracture Endpoint

    Science.gov (United States)

    Colón-Emeric, Cathleen; Pieper, Carl F.; Grubber, Janet; Van Scoyoc, Lynn; Schnell, Merritt L; Van Houtven, Courtney Harold; Pearson, Megan; Lafleur, Joanne; Lyles, Kenneth W.; Adler, Robert A.

    2016-01-01

    Purpose With ethical requirements to the enrollment of lower risk subjects, osteoporosis trials are underpowered to detect reduction in hip fractures. Different skeletal sites have different levels of fracture risk and response to treatment. We sought to identify fracture sites which cluster with hip fracture at higher than expected frequency; if these sites respond to treatment similarly, then a composite fracture endpoint could provide a better estimate of hip fracture reduction. Methods Cohort study using Veterans Affairs and Medicare administrative data. Male Veterans (n=5,036,536) aged 50-99 years receiving VA primary care between1999-2009 were included. Fractures were ascertained using ICD9 and CPT codes and classified by skeletal site. Pearson correlation coefficients, logistic regression and kappa statistics, were used to describe the correlation between each fracture type and hip fracture within individuals, without regards to the timing of the events. Results 595,579 (11.8%) men suffered 1 or more fractures and 179,597 (3.6%) suffered 2 or more fractures during the time under study. Of those with one or more fractures, rib was the most common site (29%), followed by spine (22%), hip (21%) and femur (20%). The fracture types most highly correlated with hip fracture were pelvic/acetabular (Pearson correlation coefficient 0.25, p<0.0001), femur (0.15, p<0.0001), and shoulder (0.11, p<0.0001). Conclusions Pelvic, acetabular, femur, and shoulder fractures cluster with hip fractures within individuals at greater than expected frequency. If we observe similar treatment risk reductions within that cluster, subsequent trials could consider use of a composite endpoint to better estimate hip fracture risk. PMID:26151123

  1. Statistics and thermodynamics of fracture

    Science.gov (United States)

    Chudnovsky, A.

    1984-01-01

    A probabilistic model of the fracture processes unifying the phenomenological study of long term strength of materials, fracture mechanics and statistical approaches to fracture is briefly outlined. The general framework of irreversible thermodynamics is employed to model the deterministic side of the failure phenomenon. The stochastic calculus is used to account for thg failure mechanisms controlled by chance; particularly, the random roughness of fracture surfaces.

  2. Complications in ankle fracture surgery

    OpenAIRE

    Ovaska, Mikko

    2015-01-01

    Mikko Ovaska. Complications in Ankle Fracture Surgery. Helsinki Bone and Joint Research Group, Department of Orthopaedic Surgery and Traumatology, Faculty of Medicine, University of Helsinki, Finland. Helsinki 2014. Ankle fractures are among the most frequently encountered surgically treated fractures. The operative treatment of this fracture may be associated with several complications. The most frequently encountered complications are related wound healing, and deep infection may have d...

  3. Management of osteoporotic vertebral fractures

    OpenAIRE

    Dionyssiotis, Yannis

    2010-01-01

    Yannis DionyssiotisRhodes General Hospital, Rhodes, GreeceAbstract: Osteoporotic vertebral fractures are associated with considerable reduction of quality of life, morbidity, and mortality. The management of patients with vertebral fractures should include treatment for osteoporosis and measures to reduce pain and improve mobility. This article provides information for management and rehabilitation of vertebral fractures based on clinical experience and literature.Keywords: vertebral fracture...

  4. Osteoporotic Hip and Spine Fractures

    OpenAIRE

    Cannada, Lisa K.; Hill, Brian W.

    2014-01-01

    Hip and spine fractures represent just a portion of the burden of osteoporosis; however, these fractures require treatment and often represent a major change in lifestyle for the patient and their family. The orthopedic surgeon plays a crucial role, not only in the treatment of these injuries but also providing guidance in prevention of future osteoporotic fractures. This review provides a brief epidemiology of the fractures, details the surgical techniques, and outlines the current treatment...

  5. Some probabilistic aspects of fracture

    International Nuclear Information System (INIS)

    Thomas, J.M.

    1982-01-01

    Some probabilistic aspects of fracture in structural and mechanical components are examined. The principles of fracture mechanics, material quality and inspection uncertainty are formulated into a conceptual and analytical framework for prediction of failure probability. The role of probabilistic fracture mechanics in a more global context of risk and optimization of decisions is illustrated. An example, where Monte Carlo simulation was used to implement a probabilistic fracture mechanics analysis, is discussed. (orig.)

  6. Numerical Investigation into the Effect of Natural Fracture Density on Hydraulic Fracture Network Propagation

    Directory of Open Access Journals (Sweden)

    Zhaohui Chong

    2017-07-01

    Full Text Available Hydraulic fracturing is an important method to enhance permeability in oil and gas exploitation projects and weaken hard roofs of coal seams to reduce dynamic disasters, for example, rock burst. It is necessary to fully understand the mechanism of the initiation, propagation, and coalescence of hydraulic fracture network (HFN caused by fluid flow in rock formations. In this study, a coupled hydro-mechanical model was built based on synthetic rock mass (SRM method to investigate the effects of natural fracture (NF density on HFN propagation. Firstly, the geometrical structures of NF obtained from borehole images at the field scale were applied to the model. Secondly, the micro-parameters of the proposed model were validated against the interaction between NF and hydraulic fracture (HF in physical experiments. Finally, a series of numerical simulations were performed to study the mechanism of HFN propagation. In addition, confining pressure ratio (CPR and injection rate were also taken into consideration. The results suggested that the increase of NF density drives the growth of stimulated reservoir volume (SRV, concentration area of injection pressure (CAIP, and the number of cracks caused by NF. The number of tensile cracks caused by rock matrix decrease gradually with the increase of NF density, and the number of shear cracks caused by rock matrix are almost immune to the change of NF density. The propagation orientation of HFN and the breakdown pressure in rock formations are mainly controlled by CPR. Different injection rates would result in a relatively big difference in the gradient of injection pressure, but this difference would be gradually narrowed with the increase of NF density. Natural fracture density is the key factor that influences the percentages of different crack types in HFN, regardless of the value of CPR and injection rate. The proposed model may help predict HFN propagation and optimize fracturing treatment designs in

  7. Uncertainty in hydraulic tests in fractured rock

    International Nuclear Information System (INIS)

    Ji, Sung-Hoon; Koh, Yong-Kwon

    2014-01-01

    Interpretation of hydraulic tests in fractured rock has uncertainty because of the different hydraulic properties of a fractured rock to a porous medium. In this study, we reviewed several interesting phenomena which show uncertainty in a hydraulic test at a fractured rock and discussed their origins and the how they should be considered during site characterisation. Our results show that the estimated hydraulic parameters of a fractured rock from a hydraulic test are associated with uncertainty due to the changed aperture and non-linear groundwater flow during the test. Although the magnitude of these two uncertainties is site-dependent, the results suggest that it is recommended to conduct a hydraulic test with a little disturbance from the natural groundwater flow to consider their uncertainty. Other effects reported from laboratory and numerical experiments such as the trapping zone effect (Boutt, 2006) and the slip condition effect (Lee, 2014) can also introduce uncertainty to a hydraulic test, which should be evaluated in a field test. It is necessary to consider the way how to evaluate the uncertainty in the hydraulic property during the site characterisation and how to apply it to the safety assessment of a subsurface repository. (authors)

  8. CT evaluation of acetabular fractures

    Energy Technology Data Exchange (ETDEWEB)

    Piazza, P; Girelli, G; Coran, F; Lutman, M

    1986-01-01

    The paper deals with sixteen cases of acetabular fractures studied with CT. After a short description of the normal CT findings, the different kind of fractures are reported. The usefulness of CT examination in evaluating acetabular fractures and their complications is confirmed both in conservative treatment and surgical approach.

  9. Fracture of the occipital condyle

    International Nuclear Information System (INIS)

    Wessels, L.S.

    1990-01-01

    The term fracture of the occipital condyle is a misnomer and and usually represents an extensive fracture of the posterior fossa skull base extending onto the squamous portion of the occipital bone and even further forward. These fractures should be suspected when the lower cranial nerves are affected after severe cranial trauma. Conservative management appears to be indicated. 2 figs., 5 refs

  10. Inventory parameters

    CERN Document Server

    Sharma, Sanjay

    2017-01-01

    This book provides a detailed overview of various parameters/factors involved in inventory analysis. It especially focuses on the assessment and modeling of basic inventory parameters, namely demand, procurement cost, cycle time, ordering cost, inventory carrying cost, inventory stock, stock out level, and stock out cost. In the context of economic lot size, it provides equations related to the optimum values. It also discusses why the optimum lot size and optimum total relevant cost are considered to be key decision variables, and uses numerous examples to explain each of these inventory parameters separately. Lastly, it provides detailed information on parameter estimation for different sectors/products. Written in a simple and lucid style, it offers a valuable resource for a broad readership, especially Master of Business Administration (MBA) students.

  11. Numerical modeling of the effects of roughness on flow and eddy formation in fractures

    Directory of Open Access Journals (Sweden)

    Scott Briggs

    2017-02-01

    Full Text Available The effect of roughness on flow in fractures was investigated using lattice Boltzmann method (LBM. Simulations were conducted for both statistically generated hypothetical fractures and a natural dolomite fracture. The effect of increasing roughness on effective hydraulic aperture, Izbash and Forchheimer parameters with increasing Reynolds number (Re ranging from 0.01 to 500 was examined. The growth of complex flow features, such as eddies arising near the fracture surface, was directly associated with changes in surface roughness. Rapid eddy growth above Re values of 1, followed by less rapid growth at higher Re values, suggested a three-zone nonlinear model for flow in rough fractures. This three-zone model, relating effective hydraulic conductivity to Re, was also found to be appropriate for the simulation of water flow in the natural dolomite fracture. Increasing fracture roughness led to greater eddy volumes and lower effective hydraulic conductivities for the same Re values.

  12. Multi-pathway model of nuclide transport in fractured media and its application

    International Nuclear Information System (INIS)

    Li Xun; Yang Zeping; Li Jinxuan

    2010-01-01

    In order to know the law of nuclide transport in fracture system, the basic differential equations of nuclide transport in fracture and matrix were obtained based on the dual media theory, and the general analytic solutions of nuclide transport in single fractured media with exponential attenuation source in fracture were deduced by Laplace transform, and one-dimensional multi-pathway model of nuclide transport was proposed based on dual media theory and stochastic distribution of fracture parameters. The transport of Th-229, Cs-135 and Se-79 were simulated with this model, the relative concentration of these nuclides in fracture system were predicted. Further more, it was deduced that aperture and velocity can distinctly influence transport of nuclide by comparing with the results which were simulated by single fracture model. (authors)

  13. Development of a shallow-flaw fracture assessment methodology for nuclear reactor pressure vessels

    International Nuclear Information System (INIS)

    Bass, B.R.; Bryson, J.W.; Dickson, T.L.; McAfee, W.J.; Pennell, W.E.

    1996-01-01

    Shallow-flaw fracture technology is being developed within the Heavy-Section Steel Technology (HSST) Program for application to the safety assessment of radiation-embrittled nuclear reactor pressure vessels (RPVs) containing postulated shallow flaws. Cleavage fracture in shallow-flaw cruciform beam specimens tested under biaxial loading at temperatures in the lower transition temperature range was shown to be strain-controlled. A strain-based dual-parameter fracture toughness correlation was developed and shown to be capable of predicting the effect of crack-tip constraint on fracture toughness for strain-controlled fracture. A probabilistic fracture mechanics (PFM) model that includes both the properties of the inner-surface stainless-steel cladding and a biaxial shallow-flaw fracture toughness correlation gave a reduction in probability of cleavage initiation of more than two orders of magnitude from an ASME-based reference case

  14. Pediatric maxillary fractures.

    Science.gov (United States)

    Yu, Jack; Dinsmore, Robert; Mar, Philip; Bhatt, Kirit

    2011-07-01

    Pediatric craniofacial structures differ from those of adults in many ways. Because of these differences, management of pediatric craniofacial fractures is not the same as those in adults. The most important differences that have clinical relevance are the mechanical properties, craniofacial anatomy, healing capacity, and dental morphology. This article will review these key differences and the management of pediatric maxillary fractures. From the mechanical properties' perspective, pediatric bones are much more resilient than adult bones; as such, they undergo plastic deformation and ductile failure. From the gross anatomic perspective, the relative proportion of the cranial to facial structures is much larger for the pediatric patients and the sinuses are not yet developed. The differences related to dentition and dental development are more conical crowns, larger interdental spaces, and presence of permanent tooth buds in the pediatric population. The fracture pattern, as a result of all the above, does not follow the classic Le Fort types. The maxillomandibular fixation may require circum-mandibular wires, drop wires, or Ivy loops. Interfragmentary ligatures using absorbable sutures play a much greater role in these patients. The use of plates and screws should take into consideration the future development with respect to growth centers and the location of the permanent tooth buds. Pediatric maxillary fractures are not common, require different treatments, and enjoy better long-term outcomes.

  15. Fracture Mechanics of Concrete

    DEFF Research Database (Denmark)

    Ulfkjær, Jens Peder

    Chapter 1 Chapter l contains the introduction to this thesis. The scope of the thesis is partly to investigate different numerical and analytical models based on fracture mechanical ideas, which are able to predict size effects, and partly to perform an experimental investigation on high-strength......Chapter 1 Chapter l contains the introduction to this thesis. The scope of the thesis is partly to investigate different numerical and analytical models based on fracture mechanical ideas, which are able to predict size effects, and partly to perform an experimental investigation on high......-strength concrete. Chapter 2 A description of the factors which influence the strength and cracking of concrete and high strength concrete is made. Then basic linear fracture mechanics is outlined followed by a description and evaluation of the models used to describe concrete fracture in tension. The chapter ends...... and the goveming equations are explicit and simple. These properties of the model make it a very powerful tool, which is applicable for the designing engineer. The method is also extended to reinforced concrete, where the results look very promising. The large experimental investigation on high-strength concrete...

  16. Fracture mechanics and microstructures

    International Nuclear Information System (INIS)

    Gee, M.G.; Morrell, R.

    1986-01-01

    The influence of microstructure on defects in ceramics, and the consequences of their presence for the application of fracture mechanics theories are reviewed. The complexities of microstructures, especially the multiphase nature, the crystallographic anisotropy and the resultant anisotropic physical properties, and the variation of microstructure and surface finish from point to point in real components, all lead to considerable uncertainties in the actual performance of any particular component. It is concluded that although the concepts of fracture mechanics have been and will continue to be most useful for the qualitative explanation of fracture phenomena, the usefulness as a predictive tool with respect to most existing types of material is limited by the interrelation between material microstructure and mechanical properties. At present, the only method of eliminating components with unsatisfactory mechanical properties is to proof-test them, despite the fact that proof-testing itself is limited in ability to cope with changes to the component in service. The aim of the manufacturer must be to improve quality and consistency within individual components, from component to component, and from batch to batch. The aim of the fracture specialist must be to study longer-term properties to improve the accuracy of behaviour predictions with a stronger data base. Materials development needs to concentrate on obtaining defect-free materials that can be translated into more-reliable products, using our present understanding of the influence of microstructure on strength and toughness

  17. Fracture Mechanics of Concrete

    Indian Academy of Sciences (India)

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

    the international workshop on concrete fracture, organised by A Carpinteri, at Torino ... The next question is how to bring the size effect into codes of practice on the ... analysis of the recent collapse of the World Trade Center in New York by Z P ...

  18. Oblique Axis Body Fracture

    DEFF Research Database (Denmark)

    Takai, Hirokazu; Konstantinidis, Lukas; Schmal, Hagen

    2016-01-01

    type" fracture pattern. The first patient was treated conservatively with cervical spine immobilization in a semirigid collar. However, gross displacement was noted at the 6-week follow-up visit. The second patient was therefore treated operatively by C1-C3/4 posterior fusion and the course...... for this injury and suggest early operative stabilization....

  19. Proximal femoral fractures

    DEFF Research Database (Denmark)

    Palm, Henrik; Teixidor, Jordi

    2015-01-01

    searched the homepages of the national heath authorities and national orthopedic societies in West Europe and found 11 national or regional (in case of no national) guidelines including any type of proximal femoral fracture surgery. RESULTS: Pathway consensus is outspread (internal fixation for un...

  20. Fracture mechanics and parapsychology

    Science.gov (United States)

    Cherepanov, G. P.

    2010-08-01

    The problem of postcritical deformation of materials beyond the ultimate strength is considered a division of fracture mechanics. A simple example is used to show the relationship between this problem and parapsychology, which studies phenomena and processes where the causality principle fails. It is shown that the concept of postcritical deformation leads to problems with no solution

  1. Metatarsal fracture (acute) - aftercare

    Science.gov (United States)

    ... of your 5th metatarsal bone closest to the ankle is called a Jones fracture. This area of the bone has low blood ... Swelling, pain, numbness, or tingling in your leg, ankle, or foot that becomes worse Your leg or foot turns purple Fever

  2. Analytical Estimation of Water-Oil Relative Permeabilities through Fractures

    Directory of Open Access Journals (Sweden)

    Saboorian-Jooybari Hadi

    2016-05-01

    Full Text Available Modeling multiphase flow through fractures is a key issue for understanding flow mechanism and performance prediction of fractured petroleum reservoirs, geothermal reservoirs, underground aquifers and carbon-dioxide sequestration. One of the most challenging subjects in modeling of fractured petroleum reservoirs is quantifying fluids competition for flow in fracture network (relative permeability curves. Unfortunately, there is no standard technique for experimental measurement of relative permeabilities through fractures and the existing methods are very expensive, time consuming and erroneous. Although, several formulations were presented to calculate fracture relative permeability curves in the form of linear and power functions of flowing fluids saturation, it is still unclear what form of relative permeability curves must be used for proper modeling of flow through fractures and consequently accurate reservoir simulation. Basically, the classic linear relative permeability (X-type curves are used in almost all of reservoir simulators. In this work, basic fluid flow equations are combined to develop a new simple analytical model for water-oil two phase flow in a single fracture. The model gives rise to simple analytic formulations for fracture relative permeabilities. The model explicitly proves that water-oil relative permeabilities in fracture network are functions of fluids saturation, viscosity ratio, fluids density, inclination of fracture plane from horizon, pressure gradient along fracture and rock matrix wettability, however they were considered to be only functions of saturations in the classic X-type and power (Corey [35] and Honarpour et al. [28, 29] models. Eventually, validity of the proposed formulations is checked against literature experimental data. The proposed fracture relative permeability functions have several advantages over the existing ones. Firstly, they are explicit functions of the parameters which are known for

  3. Characterising rock fracture aperture-spacing relationships using power-law relationships: some considerations

    Science.gov (United States)

    Brook, Martin; Hebblewhite, Bruce; Mitra, Rudrajit

    2016-04-01

    The size-scaling of rock fractures is a well-studied problem in geology, especially for permeability quantification. The intensity of fractures may control the economic exploitation of fractured reservoirs because fracture intensity describes the abundance of fractures potentially available for fluid flow. Moreover, in geotechnical engineering, fractures are important for parameterisation of stress models and excavation design. As fracture data is often collected from widely-spaced boreholes where core recovery is often incomplete, accurate interpretation and representation of fracture aperture-frequency relationships from sparse datasets is important. Fracture intensity is the number of fractures encountered per unit length along a sample scanline oriented perpendicular to the fractures in a set. Cumulative frequency of fractures (F) is commonly related to fracture aperture (A) in the form of a power-law (F = aA-b), with variations in the size of the a coefficient between sites interpreted to equate to fracture frequency for a given aperture (A). However, a common flaw in this approach is that even a small change in b can have a large effect on the response of the fracture frequency (F) parameter. We compare fracture data from the Late Permian Rangal Coal Measures from Australia's Bowen Basin, with fracture data from Jurassic carbonates from the Sierra Madre Oriental, northeastern Mexico. Both power-law coefficient a and exponent b control the fracture aperture-frequency relationship in conjunction with each other; that is, power-laws with relatively low a coefficients have relatively high b exponents and vice versa. Hence, any comparison of different power-laws must take both a and b into consideration. The corollary is that different sedimentary beds in the Sierra Madre carbonates do not show ˜8× the fracture frequency for a given fracture aperture, as based solely on the comparison of coefficient a. Rather, power-law "sensitivity factors" developed from both

  4. Distinguishing stress fractures from pathologic fractures: a multimodality approach

    International Nuclear Information System (INIS)

    Fayad, Laura M.; Kamel, Ihab R.; Kawamoto, Satomi; Bluemke, David A.; Fishman, Elliot K.; Frassica, Frank J.

    2005-01-01

    Whereas stress fractures occur in normal or metabolically weakened bones, pathologic fractures occur at the site of a bone tumor. Unfortunately, stress fractures may share imaging features with pathologic fractures on plain radiography, and therefore other modalities are commonly utilized to distinguish these entities. Additional cross-sectional imaging with CT or MRI as well as scintigraphy and PET scanning is often performed for further evaluation. For the detailed assessment of a fracture site, CT offers a high-resolution view of the bone cortex and periosteum which aids the diagnosis of a pathologic fracture. The character of underlying bone marrow patterns of destruction can also be ascertained along with evidence of a soft tissue mass. MRI, however, is a more sensitive technique for the detection of underlying bone marrow lesions at a fracture site. In addition, the surrounding soft tissues, including possible involvement of adjacent muscle, can be well evaluated with MRI. While bone scintigraphy and FDG-PET are not specific, they offer a whole-body screen for metastases in the case of a suspected malignant pathologic fracture. In this review, we present select examples of fractures that underscore imaging features that help distinguish stress fractures from pathologic fractures, since accurate differentiation of these entities is paramount. (orig.)

  5. Scanning anisotropy parameters in horizontal transversely isotropic media

    KAUST Repository

    Masmoudi, Nabil; Stovas, Alexey; Alkhalifah, Tariq Ali

    2016-01-01

    in reservoir characterisation, specifically in terms of fracture delineation. We propose a travel-time-based approach to estimate the anellipticity parameter η and the symmetry axis azimuth ϕ of a horizontal transversely isotropic medium, given an inhomogeneous

  6. 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

  7. Cough-induced rib fractures.

    Science.gov (United States)

    Hanak, Viktor; Hartman, Thomas E; Ryu, Jay H

    2005-07-01

    To define the demographic, clinical, and radiological features of patients with cough-induced rib fractures and to assess potential risk factors. For this retrospective, single-center study, we identified all cases of cough-induced rib fractures diagnosed at the Mayo Clinic in Rochester, Minn, over a 9-year period between January 1, 1996, and January 31, 2005. Bone densitometry data from patients' medical records were analyzed, and T scores were used to classify patients into bone density categories. The mean +/- SD age of the 54 study patients at presentation was 55+/-17 years, and 42 patients (78%) were female. Patients presented with chest wall pain after onset of cough. Rib fracture was associated with chronic cough (> or =3 weeks' duration) in 85% of patients. Rib fractures were documented by chest radiography, rib radiography, computed tomography, or bone scan. Chest radiography had been performed in 52 patients and revealed rib fracture in 30 (58%). There were 112 fractured ribs in 54 patients. One half of patients had more than one fractured rib. Right-sided rib fractures alone were present in 17 patients (26 fractured ribs), left-sided in 23 patients (35 fractured ribs), and bilateral in 14 patients (51 fractured ribs). The most commonly fractured rib on both sides was rib 6. The fractures were most common at the lateral aspect of the rib cage. Bone densitometry was done in 26 patients and revealed osteopenia or osteoporosis in 17 (65%). Cough-induced rib fractures occur primarily in women with chronic cough. Middle ribs along the lateral aspect of the rib cage are affected most commonly. Although reduced bone density is likely a risk factor, cough-induced rib fractures can occur in the presence of normal bone density.

  8. Sealing of rock fractures

    International Nuclear Information System (INIS)

    Pusch, R.; Erlstroem, M.; Boergesson, L.

    1985-12-01

    The major water-bearing fractures in granite usually from fairly regular sets but the extension and degree of connectivity is varying. This means that only a few fractures that are interconnected with the deposition holes and larger water-bearing structures in a HLW repository are expected and if they can be identified and cut off through sealing it would be possible to improve the isolation of waste packages very effectively. Nature's own fracture sealing mechanisms may be simulated and a survey of the involved processes actually suggests a number of possible filling methods and substances. Most of them require high temperature and pressure and correspondingly sophisticated techniques, but some are of potential interest for immediate application with rather moderate effort. Such a technique is to fill the fractures with clayey substances which stay flexible and low-permeable provided that they remain physically and chemically intact. It is demonstrated in the report that effective grouting requires a very low viscosity and shear strength of the substance and this can be achieved by mechanical agitation as demonstrated in this report. Thus, by superimposing static pressure and shear waves induced by percussion hammering at a suitable frequency, clays and fine-grained silts as well as cement can be driven into fractures with an average aperture as small as 0.1 mm. Experiments were made in the laboratory using concrete and steel plates, and a field pilot test was also conducted under realistic conditions on site in Stripa. They all demonstrated the practicality of the 'dynamic injection technique' and that the fluid condition of the grouts yielded complete filling of the injected space to a considerable distance from the injection point. The field test indicated a good sealing ability as well as a surprisingly high resistance to erosion and piping. (author)

  9. Extending Topological Approaches to Microseismic-Derived 3D Fracture Networks

    Science.gov (United States)

    Urbancic, T.; Bosman, K.; Baig, A.; Ardakani, E. P.

    2017-12-01

    Fracture topology is important for determining the fluid-flow characteristics of a fracture network. In most unconventional petroleum applications, flow through subsurface fracture networks is the primary source of production, as matrix permeability is often in the nanodarcy range. Typical models of reservoir discrete fracture networks (DFNs) are constructed using fracture orientation and average spacing, without consideration of how the connectivity of the fracture network aids the percolation of hydrocarbons back to the wellbore. Topological approaches to DFN characterization have been developed and extensively used in analysis of outcrop data and aerial photography. Such study of the surface expression of fracture networks is straight-forward, and the physical form of the observed fractures is directly reflected in the parameters used to describe the topology. However, this analysis largely ignores the three-dimensional nature of natural fracture networks, which is difficult to define accurately in geological studies. SMTI analysis of microseismic event distributions can produce DFNs, where each event is represented by a penny-shaped crack with radius and orientation determined from the frequency content of the waveforms and assessment of the slip instability of the potential fracture planes, respectively. Analysis of the geometric relationships between a set of fractures can provide details of intersections between fractures, and thus the topological characteristics of the fracture network. Extension of existing 2D topology approaches to 3D fracture networks is non-trivial. In the 2D case, a fracture intersection is a single point (node), and branches connect adjacent nodes along fractures. For the 3D case, intersection "nodes" become lines, and connecting nodes to find branches becomes more complicated. There are several parameters defined in 2D topology to quantify the connectivity of the fracture network. Equivalent quantities must be defined and calibrated

  10. On the evaluation of steam assisted gravity drainage in naturally fractured oil reservoirs

    Directory of Open Access Journals (Sweden)

    Seyed Morteza Tohidi Hosseini

    2017-06-01

    Full Text Available Steam Assisted Gravity Drainage (SAGD as a successful enhanced oil recovery (EOR process has been applied to extract heavy and extra heavy oils. Huge amount of global heavy oil resources exists in carbonate reservoirs which are mostly naturally fractured reservoirs. Unlike clastic reservoirs, few studies were carried out to determine the performance of SAGD in carbonate reservoirs. Even though SAGD is a highly promising technique, several uncertainties and unanswered questions still exist and they should be clarified for expansion of SAGD methods to world wide applications especially in naturally fractured reservoirs. In this communication, the effects of some operational and reservoir parameters on SAGD processes were investigated in a naturally fractured reservoir with oil wet rock using CMG-STARS thermal simulator. The purpose of this study was to investigate the role of fracture properties including fracture orientation, fracture spacing and fracture permeability on the SAGD performance in naturally fractured reservoirs. Moreover, one operational parameter was also studied; one new well configuration, staggered well pair was evaluated. Results indicated that fracture orientation influences steam expansion and oil production from the horizontal well pairs. It was also found that horizontal fractures have unfavorable effects on oil production, while vertical fractures increase the production rate for the horizontal well. Moreover, an increase in fracture spacing results in more oil production, because in higher fracture spacing model, steam will have more time to diffuse into matrices and heat up the entire reservoir. Furthermore, an increase in fracture permeability results in process enhancement and ultimate recovery improvement. Besides, diagonal change in the location of injection wells (staggered model increases the recovery efficiency in long-term production plan.

  11. Social inequality and hip fracture

    DEFF Research Database (Denmark)

    Harvey, N. C.; Hansen, L.; Judge, A.

    2015-01-01

    Social inequality appears to be increasing in many countries. We explored whether risk of hip fracture was associated with markers of inequality and whether these relationships changed with time, using data from Danish Health Registries. Methods: All patients 60 years or older with a primary hip...... fracture (ICD10: S720, S721, S722 and S729) were identified from 1 January 1995 to 31 December 2011. Hip fracture patients were matched 1:1 on age, gender and year of fracture to a non-hip fracture control. An individual's education attainment was defined as basic, secondary or higher, and their income...

  12. Seismic characterization of fracture properties

    International Nuclear Information System (INIS)

    Myer, L.R.; Hopkins, D.; Cook, N.G.W.; Pyrak-Nolte, L.J.

    1990-01-01

    The purpose of this paper is to show that there is a relationship, both empirical and theoretical, between the measured seismic response, the mechanical stiffness (also referred to as specific stiffness) of fractures and their hydraulic conductivity. Laboratory measurements of the mechanical stiffness, hydraulic conductivity and seismic properties of natural fractures are summarized. A theoretical model for the amplitude and group time delay for compressional and shear waves transmitted across a single fracture is presented. Predictions based on this model are compared with laboratory measurements. Finally, the results for a single fracture are extended to multiple parallel fractures. 13 refs., 6 figs

  13. Laser induced damage and fracture in fused silica vacuum windows

    International Nuclear Information System (INIS)

    Campbell, J.H.; Hurst, P.A.; Heggins, D.D.; Steele, W.A.; Bumpas, S.E.

    1996-11-01

    Laser-induced damage, that initiates catastrophic fracture, has been observed in large (≤61 cm dia) fused silica lenses that also serve as vacuum barriers in Nova and Beamlet lasers. If the elastic stored energy in the lens is high enough, the lens will fracture into many pieces (implosion). Three parameters control the degree of fracture in the vacuum barrier window: elastic stored energy (tensile stress), ratio of window thickness to flaw depth, and secondary crack propagation. Fracture experiments were conducted on 15-cm dia fused silica windows that contain surface flaws caused by laser damage. Results, combined with window failure data on Beamlet and Nova, were used to develop design criteria for a ''fail-safe'' lens (that may catastrophically fracture but not implode). Specifically, the window must be made thick enough so that the peak tensile stress is less than 500 psi (3.4 MPa) and the thickness/critical flaw size is less than 6. The air leak through the window fracture and into the vacuum must be rapid enough to reduce the load on the window before secondary crack growth occurs. Finite element stress calculations of a window before and immediately following fracture into two pieces show that the elastic stored energy is redistributed if the fragments ''lock'' in place and thereby bridge the opening. In such cases, the peak stresses at the flaw site can increase, leading to further (i.e. secondary) crack growth

  14. 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.

  15. [Vertebral fractures in children with Type I Osteogenesis imperfecta].

    Science.gov (United States)

    Sepúlveda, Andrea M; Terrazas, Claudia V; Sáez, Josefina; Reyes, María L

    2017-06-01

    Osteogenesis imperfecta (OI) is an hereditary disease affecting conective tissue, mainly associated to growth retardation and pathological fractures. OI type I (OI type I), is the mildest, most often, and homogeneous in its fenotype. Vertebral fractures are the most significant complications, associated to skeletical and cardiopulmonary morbidity. To characterize clinically a cohort of children with OI type I. A cohort of OI type I children younger than 20 year old was evaluated. Demographic, clinical, biochemical and radiological data were registered. Sixty seven patients were included, 55% male, 69% resident in the Metropolitan Region. The mean age of diagnose was 2.9 years, 70% presented vertebral fractures on follow-up, mostly thoracic, and 50% before the age of 5 years. Fifty percentage presented vertebral fractures at diagnose, which was about the age of 5 years. Bone metabolic parameters were in the normal range, without significant change at the moment of vertebral fractures. Calcium intake was found to be below American Academy of Pediatrics recommendations at the time of the first fracture. In this study OI type I has an early diagnose, and vertebral fractures show a high incidence, mostly in toddlers. Calcium intake was found to be below reccomended values, and should be closely supervised in these patients.

  16. Experimental and Numerical Investigation of Rock Dynamic Fracture

    Directory of Open Access Journals (Sweden)

    Aliasghar Mirmohammadlou

    2017-06-01

    Full Text Available Rapid development of engineering activities expands through a variety of rock engineering processes such as drilling, blasting, mining and mineral processing. These activities require rock dynamic fracture mechanics method to characterize the rock behavior. Dynamic fracture toughness is an important parameter for the analysis of engineering structures under dynamic loading. Several experimental methods are used for determination of dynamic fracture properties of materials. Among them, the Hopkinson pressure bar and the drop weight have been frequently used for rocks. On the other hand, numerical simulations are very useful in dynamic fracture studies. Among vast variety of numerical techniques, the powerful extended finite element method (XFEM enriches the finite element approximation with appropriate functions extracted from the fracture mechanics solution around a crack-tip. The main advantage of XFEM is its capability in modeling different on a fixed mesh, which can be generated without considering the existence of discontinuities. In this paper, first, the design of a drop weight test setup is presented. Afterwards, the experimental tests on igneous (basalt and calcareous (limestone rocks with single-edge-cracked bend specimen are discussed. Then, each experimental test is modeled with the XFEM code. Finally, the obtained experimental and numerical results are compared. The results indicate that the experimentally predicted dynamic fracture toughness has less than 8 percent difference with calculated dynamic fracture toughness from extended finite element method

  17. 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

  18. Status report on experiments and modelling of the cleavage fracture behaviour of F82Hmod using local fracture grid. Task TTMS-005

    International Nuclear Information System (INIS)

    Riesch-Oppermann, H.; Walter, M.

    2001-09-01

    Within the European Fusion Technology Programme framework, a fracture mechanics description of the material behaviour in the ductile to brittle transition-regime is developed using local fracture criteria. Based on experimental results using axisymmetrically notched and pre-cracked specimens together with a numerical stress analysis at fracture load, a statistical evaluation of cleavage fracture parameters can be performed along the lines described in various code schemes such as the British Energy R6-Code or the ESIS P6 procedure. The report contains results of the experimental characterization of the deformation and fracture behaviour of the fusion candidate RAFM steel variant F82Hmod, details and background of the numerical procedure for cleavage fracture parameter determination as well as additional statistical inference methods for transferability analysis. Fractographic results give important information about fracture mode and fracture origin sites and their location. Numerical prediction of fracture origin distribution is an important tool for transferability assessment. Future issues comprise constraint effect and ductile damage as well as incorporation of irradiation effects, which are topically addressed. The methodology developed and described in the present report will be applied to characterize material behaviour of future RAFM variants as the EUROFER 97, for which analysis is currently under way. (orig.)

  19. Pubic insufficiency fracture: MRI findings

    International Nuclear Information System (INIS)

    Min, Tae Kyu; Lee, Yeon Soo; Park, Jeong Mi; Kim, Jee Young; Chung, Hong Jun; Lee, Eun Hee; Lee, Eun Ja; Kang, So Won; Han Tae Il

    2000-01-01

    To evaluate the characteristic MRI findings of pubic insufficiency fracture. In nine cases of pubic insufficiency fracture, the findings of plain radiography (n=9), MRI (n=9), and bone scintigraphy (n=8) were reviewed. We retrospectively analyzed, with regard to fracture site, the destructive pattern revealed by plain radiography, and uptake by other pelvic bones, as demonstrated by RI bone scanning. The MR findings evaluated were the fracture gap and its signal intensity, the site and signal intensity of the soft tissue mass, and other pelvic bone fractures. Plain radiography revealed osteolysis and sclerosis of pubic bone in eight of nine cases (89%), and parasymphyseal fractures in seven (78%). RI indicated uptake by the sacrum in six cases (66%), and by the ilium in three (33%). MR findings of fracture gap (seven cases, 78%) were hypo to isointensity on T1WI, hyper intensity on T2WI and the absence of contrast enhancement. Soft tissue masses were found in seven cases (78%); in four of these the location was parasymphyseal, and in three, surrounding muscle was involved. Hypo to isointensity was revealed by T1WI, hyperintensity by T2WI, and there was peripheral enhancement. Other associated pelvic bone fractures involved the sacrum in seven cases and the ilium in four. The characteristic MR findings of pubic insufficiency fracture were parasymphyseal location, fracture gap, peripherally enhanced soft tissue mass formation, and fractures of other pelvic bones, namely the sacrum and ilium

  20. Seismic signatures of the Lodgepole fractured reservoir in Utah-Wyoming overthrust belt

    Energy Technology Data Exchange (ETDEWEB)

    Parra, J.; Collier, H.; Angstman, B.

    1997-08-01

    In low porosity, low permeability zones, natural fractures are the primary source of permeability which affect both production and injection of fluids. The open fractures do not contribute much to porosity, but they provide an increased drainage network to any porosity. An important approach to characterizing the fracture orientation and fracture permeability of reservoir formations is one based upon the effects of such conditions on the propagation of acoustic and seismic waves in the rock. We present the feasibility of using seismic measurement techniques to map the fracture zones between wells spaced 2400 ft at depths of about 1000 ft. For this purpose we constructed computer models (which include azimuthal anisotropy) using Lodgepole reservoir parameters to predict seismic signatures recorded at the borehole scale, crosswell scale, and 3 D seismic scale. We have integrated well logs with existing 2D surfaces seismic to produce petrophysical and geological cross sections to determine the reservoir parameters and geometry for the computer models. In particular, the model responses are used to evaluate if surface seismic and crosswell seismic measurements can capture the anisotropy due to vertical fractures. Preliminary results suggested that seismic waves transmitted between two wells will propagate in carbonate fracture reservoirs, and the signal can be received above the noise level at the distance of 2400 ft. In addition, the large velocities contrast between the main fracture zone and the underlying unfractured Boundary Ridge Member, suggested that borehole reflection imaging may be appropriate to map and fracture zone thickness variation and fracture distributions in the reservoir.

  1. Elastodynamic fracture analyses of large crack-arrest experiments

    International Nuclear Information System (INIS)

    Bass, B.R.; Pugh, C.E.; Walker, J.K.

    1985-01-01

    Results obtained to date show that the essence of the run-arrest events, including dynamic behavior, is being modeled. Refined meshes and optimum solution algorithms are important parameters in elastodynamic analysis programs to give sufficient resolution to the geometric and time-dependent aspects of fracture analyses. Further refinements in quantitative representation of material parameters and the inclusion of rate dependence through viscoplastic modeling is expected to give an even more accurate basis for assessing the fracture behavior of reactor pressure vessels under PTS and other off-normal loading conditions

  2. Elastic robust intramedullary nailing for forearm fracture in children

    Directory of Open Access Journals (Sweden)

    Wasem, Jürgen

    2006-01-01

    Full Text Available Background: Forearm fractures are the most common fractures in children (23% of all fractures. Basically there are two treatment options available for diaphyseal forearm fractures in children: closed reduction with cast immobilisation (conservative therapy and the elastic stable intramedullary nailing (ESIN. Treatment decision is influenced by the doctor's estimation of fracture instability. Stable fractures can be treated conservatively whereas instable forearm shaft fractures can be treated according the following three treatment strategies: 1. conservative therapy in an outpatient setting 2. conservative therapy in the operating room in attendance to change to ESIN in case that no stabilisation can be achieved with cast immobilisation 3. immediate treatment with ESIN in the operating room. Objectives: Aim of this Health Technology Assessment (HTA report is to assess and report the published evidence concerning effectiveness and cost-effectiveness of ESIN as a treatment option for diaphyseal forearm fractures in children and to identify future research need. Important parameters for the assessment of effectiveness are objective parameters (axis deviation, losses of motion, and numbers of reductions in case of redislocations and subjective parameters (pain or impairment in quality of life. Furthermore, a health economic evaluation shall be done which refers to the costs of the different therapy strategies. Methods: An extensive, systematic literature search in medical, economic, and HTA literature databases was performed. Relevant data were extracted and synthesised. Results: Three cohort studies and seven case series have been identified. Controlled clinical studies, systematic reviews and/or HTA reports that gave evidence to answer the own study question have not been found. The identified studies partly differed in respect of defined indication for ESIN, study population and treatment strategies. For that reason comparability of results was

  3. Radionuclide transport in fractured porous media -- Analytical solutions for a system of parallel fractures with a kinetic solubility-limited dissolution model

    International Nuclear Information System (INIS)

    Li, S.H.; Chen, C.T.

    1997-01-01

    Analytical solutions are developed for the problem of radionuclide transport in a system of parallel fractures situated in a porous rock matrix. A kinetic solubility-limited dissolution model is used as the inlet boundary condition. The solutions consider the following processes: (a) advective transport in the fractures, (b) mechanical dispersion and molecular diffusion along the fractures, (c) molecular diffusion from a fracture to the porous matrix, (d) molecular diffusion within the porous matrix in the direction perpendicular to the fracture axis, (e) adsorption onto the fracture wall, (f) adsorption within the porous matrix, and (g) radioactive decay. The solutions are based on the Laplace transform method. The general transient solution is in the form of a double integral that is evaluated using composite Gauss-Legendre quadrature. A simpler transient solution that is in the form of a single integral is also presented for the case that assumes negligible longitudinal dispersion along the fractures. The steady-state solutions are also provided. A number of examples are given to illustrate the effects of the following important parameters: (a) fracture spacings, (b) dissolution-rate constants, (c) fracture dispersion coefficient, (d) matrix retardation factor, and (e) fracture retardation factor

  4. Dynamics and Scaling Properties of Fractures in clay-like Materials

    Energy Technology Data Exchange (ETDEWEB)

    Walmann, Thomas

    1998-12-31

    Computer models that can help oil companies predict realistic and physically correct fracture patterns are important. To verify such a model, experiments described in this thesis were undertaken, using wet clay and powder. The main focus was on extensional fractures, but other types of fractures were also studied. High resolution digital images of the fracture patterns were recorded and analyzed using statistical physics and fractal geometry. The characteristic shapes and size distributions of individual fractures and the overall fracture patterns obtained from laboratory model studies were compared to results from aerial photographs of a fracture pattern in a collapsed glacier that had undergone a similar deformation. A new scaling relation (a power-law) between the length of a fracture and the projected area is derived for fractures formed during clay model experiments. This scaling relation is found also in a field study of a fracture pattern in a glacier. The forms of the different distributions that characterizes fractures in clay experiments are discussed. Several characteristic lengths are associated with the laboratory experiments. They are related to the sample size and shape, the model material and the nature of the imposed deformation. The roughness of the fracture traces obtained from powder experiments was found to have a self-affine form. The roughness, or Hurst exponent, was found to have the value 0.73, plus or minus 0.09. A large number of interacting fractures were formed in the systems studied, and under such conditions the fluctuations about the direction perpendicular to the principle strain direction are influenced by neighbouring fractures. As expected, an upper cutoff for the scaling range was observed. But the length at which the crossover from a self-affine shape to a flat shape took place did not depend systematically on any of the experimental parameters or characteristic length scales. The total fracture trace patterns could not be

  5. [Treatment strategy and planning for pilon fractures].

    Science.gov (United States)

    Mittlmeier, Thomas; Wichelhaus, Alice

    2017-08-01

    Pilon fractures are mainly severe and prognostically serious injuries with a high rate of relevant soft tissue involvement. The adequate decision making and choice of treatment in the early phase of trauma are of paramount importance for the final outcome. This essentially encompasses the management of the soft tissue damage, the surgical planning and the differentiated selection of procedures. Most concepts of staged treatment nowadays offer a wide range of options which are integrated into expert-based algorithms. The aim of the present analysis was to display the strategy variations for the treatment of pilon fractures taking into account the advantages and disadvantages of the corresponding treatment concepts. A staged procedure including primary closed reduction employing ligamentotaxis and fixation of the joints of the hindfoot via tibiocalcaneal metatarsal fixation offers a safe basis for consecutive imaging and the selection of specific approaches for definitive reconstruction. A simultaneous reconstruction and fixation of the fibula during the primary intervention are generally not recommended in order to avoid any limitations for subsequent reconstructive procedures. A time frame for definitive reconstruction covers a period of up to 3 weeks after trauma and allows a detailed planning considering the individual dynamics of the soft tissue situation and any logistic requirements. For the choice of the definitive treatment concept a wide range of procedures and implants are available. There are also valid concepts for primary treatment of defined fracture constellations while primary arthrodesis represents a solution in cases of major destruction of the joint surface. Knowledge of the multiple procedural variations for pilon fracture treatment creates the basis to optimize the treatment modalities and to take into account individual parameters of the fracture.

  6. Fracture toughness of fibrous composite materials

    Science.gov (United States)

    Poe, C. C., Jr.

    1984-01-01

    Laminates with various proportions of 0 deg, 45 deg, and 90 deg plies were fabricated from T300/5208 and T300/BP-907 graphite/epoxy prepreg tape material. The fracture toughness of each laminate orientation or lay-up was determined by testing center-cracked specimens, and it was also predicted with the general fracture-toughness parameter. The predictions were good except when crack-tip splitting was large, at which time the toughness and strengths tended to be underpredicted. By using predictions, a parametric study was also made of factors that influence fracture toughness. Fiber and matrix properties as well as lay-up were investigated. Without crack-tip splitting, fracture toughness increases in proportion to fiber strength and fiber volume fraction, increases linearly with E(22)/E(11), is largest when the modulus for non-0 deg fibers is greater than that of 0 deg fibers, and is smallest for 0(m)/90(p)(s) lay-ups. (The E(11) and E(22) are Young's moduli of the lamina parallel to and normal to the direction of the fibers, respectively). For a given proportion of 0 deg plies, the most notch-sensitive lay-ups are 0(m)/90(p)(s) and the least sensitive are 0(m)/45(n)(s) and alpha(s). Notch sensitivity increases with the proportion of 0 deg plies and decreases with alpha. Strong, tough matrix materials, which inhibit crack-tip splitting, generally lead to minimum fracture toughness.

  7. Permeability and dispersivity of variable-aperture fracture systems

    International Nuclear Information System (INIS)

    Tsang, Y.W.; Tsang, C.F.

    1990-01-01

    A number of recent experiments have pointed out the need of including the effects of aperture variation within each fracture in predicting flow and transport properties of fractured media. This paper introduces a new approach in which medium properties, such as the permeability to flow and dispersivity in tracer transport, are correlated to only three statistical parameters describing the fracture aperture probability distribution and the aperture spatial correlation. We demonstrate how saturated permeability and relative permeabilities for flow, as well as dispersion for solute transport in fractures may be calculated. We are in the process of examining the applicability of these concepts to field problems. Results from the evaluation and analysis of the recent Stripa-3D field data are presented. 13 refs., 10 figs

  8. Slug flow model for infiltration into fractured porous media

    International Nuclear Information System (INIS)

    Martinez, M.J.

    1999-01-01

    A model for transient infiltration into a periodically fractured porous layer is presented. The fracture is treated as a permeable-walled slot and the moisture distribution is in the form of a slug being an advancing meniscus. The wicking of moisture from the fracture to the unsaturated porous matrix is a nonlinear diffusion process and is approximately by self-similar solutions. The resulting model is a nonlinear Volterra integral equation with a weakly singular kernel. Numerical analysis provides solutions over a wide range of the parameter space and reveals the asymptotic forms of the penetration of this slug in terms of dimensionless variables arising in the model. The numerical solutions corroborate asymptotic results given earlier by Nitao and Buscheck (1991), and by Martinez (1988). Some implications for the transport of liquid in fractured rock are discussed

  9. Applicability and interpretation of fracture test methods for metals

    International Nuclear Information System (INIS)

    Langford, W.J.

    1978-05-01

    Fracture tests are conducted usually out of a conviction (sometimes only vaguely defined) that they will guarantee a certain level of protecton from metal failure. Qualitative tests, such as the Charpy V-notch, produce results which cannot be rigorously related to a measure of fracture tolerance: rather, they indicate metal quality so that fracture tolerance may be inferred. Quantitative tests on the other hand provide parameters which may be used directly in equations to determine the likelihood of fracture. Both types of tests have limitations which should be understood: the paper tries to provide guidance on the relative merits of either approach for a particular purpose, and gives an insight into near-future test methods which will extend the range of usefullness of quantitative tests. (author)

  10. Theoretical aspects of fracture mechanics

    Science.gov (United States)

    Atkinson, C.; Craster, R. V.

    1995-03-01

    In this review we try to cover various topics in fracture mechanics in which mathematical analysis can be used both to aid numerical methods and cast light on key features of the stress field. The dominant singular near crack tip stress field can often be parametrized in terms of three parameters K(sub I), K(sub II) and K(sub III) designating three fracture modes each having an angular variation entirely specified for the stress tensor and displacement vector. These results and contact zone models for removing the interpenetration anomaly are described. Generalizations of the above results to viscoelastic media are described. For homogeneous media with constant Poisson's ratio the angular variation of singular crack tip stresses and displacements are shown to be the same for all time and the same inverse square root singularity as occurs in the elastic medium case is found (this being true for a time varying Poisson ratio too). Only the stress intensity factor varies through time dependence of loads and relaxation properties of the medium. For cracks against bimaterial interfaces both the stress singularity and angular form evolve with time as a function of the time dependent properties of the bimaterial. Similar behavior is identified for sharp notches in viscoelastic plates. The near crack tip behavior in material with non-linear stress strain laws is also identified and stress singularities classified in terms of the hardening exponent for power law hardening materials. Again for interface cracks the near crack tip behavior requires careful analysis and it is shown that more than one singular term may be present in the near crack tip stress field. A variety of theory and applications is presented for inhomogeneous elastic media, coupled thermoelasticity etc. Methods based on reciprocal theorems and dual functions which can also aid in getting awkward singular stress behavior from numerical solutions are also reviewed. Finally theoretical calculations of fiber

  11. Fracture network evaluation program (FraNEP): A software for analyzing 2D fracture trace-line maps

    Science.gov (United States)

    Zeeb, Conny; Gomez-Rivas, Enrique; Bons, Paul D.; Virgo, Simon; Blum, Philipp

    2013-10-01

    Fractures, such as joints, faults and veins, strongly influence the transport of fluids through rocks by either enhancing or inhibiting flow. Techniques used for the automatic detection of lineaments from satellite images and aerial photographs, LIDAR technologies and borehole televiewers significantly enhanced data acquisition. The analysis of such data is often performed manually or with different analysis software. Here we present a novel program for the analysis of 2D fracture networks called FraNEP (Fracture Network Evaluation Program). The program was developed using Visual Basic for Applications in Microsoft Excel™ and combines features from different existing software and characterization techniques. The main novelty of FraNEP is the possibility to analyse trace-line maps of fracture networks applying the (1) scanline sampling, (2) window sampling or (3) circular scanline and window method, without the need of switching programs. Additionally, binning problems are avoided by using cumulative distributions, rather than probability density functions. FraNEP is a time-efficient tool for the characterisation of fracture network parameters, such as density, intensity and mean length. Furthermore, fracture strikes can be visualized using rose diagrams and a fitting routine evaluates the distribution of fracture lengths. As an example of its application, we use FraNEP to analyse a case study of lineament data from a satellite image of the Oman Mountains.

  12. 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.

  13. 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

  14. Correlation of physical properties of ceramic materials with resistance to fracture by thermal shock

    Science.gov (United States)

    Lidman, W G; Bobrowsky, A R

    1949-01-01

    An analysis is made to determine which properties of materials affect their resistance to fracture by thermal stresses.From this analysis, a parameter is evaluated that is correlated with the resistance of ceramic materials to fracture by thermal shock as experimentally determined. This parameter may be used to predict qualitatively the resistance of a material to fracture by thermal shock. Resistance to fracture by thermal shock is shown to be dependent upon the following material properties: thermal conductivity, tensile strength, thermal expansion, and ductility modulus. For qualitative prediction of resistance of materials to fracture by thermal shock, the parameter may be expressed as the product of thermal conductivity and tensile strength divided by the product of linear coefficient of thermal expansion and ductility modulus of the specimen.

  15. Fracture network model of the groundwater flow in the Romuvaara site

    International Nuclear Information System (INIS)

    Poteri, A.; Laitinen, M.

    1997-01-01

    In the study, computer codes are employed to analyse the groundwater flow patterns in the sparcely fractured intact rock at the Romuvaara site. The new fracture data gathered during the detailed site characterisation phase demonstrated that the characteristic properties of fractures can be estimated quite reliably from few boreholes and outcrops. Results obtained by employing new methods, like the use of borehole-TV, changed the fracture intensity of the potential water conducting fractures compared to the earlier model. In the preliminary site investigation phase only the orientated fractures were used to derive the parameters of the intact rock. In the present model all the fractures outside the known fracture zones are used. The hydraulic conductivity tensor of the intact rock was estimated with the fracture network model. The flow simulations were calculated for a 16 x 16 x 16 m 3 rock volume and about 2000 fractures. The flow rate distribution through the cross sectional area of the disposal canisters was calculated for a set of ten realisations and a large number of different canister positions. The total number of canister positions simulated was 2200. The flow distribution in larger volume was studied using a method that searched the flow routes of highest conductance. The flow routes were examined into north-south, east-west and vertical directions. Flow routes along homogeneous and heterogeneous fractures were compared. (21 refs.)

  16. Fracture mechanics of ceramics. Vol. 8. Microstructure, methods, design, and fatigue

    International Nuclear Information System (INIS)

    Bradt, R.C.; Evans, A.G.; Hasselman, D.P.H.; Lange, F.F.

    1986-01-01

    This paper presents information on the following topics: fracture mechanics and microstructures; non-lubricated sliding wear of Al 2 O 3 , PSZ and SiC; mixed-mode fracture of ceramics; some fracture properties of alumina-containing electrical porcelains; transformation toughening in the Al 2 O 3 -Cr 2 O 3 /ZrO 2 -HfO 2 system; strength toughness relationships for transformation toughened ceramics; tensile strength and notch sensitivity of Mg-PSZ; fracture mechanisms in lead zirconate titanate ceramics; loading-unloading techniques for determining fracture parameters of brittle materials utilizing four-point bend, chevron-notched specimens; application of the potential drop technique to the fracture mechanics of ceramics; ceramics-to-metal bonding from a fracture mechanics perspective; observed changes in fracture strength following laser irradiation and ion beam mixing of Ni overlayers on sintered alpha-SiC; crack growth in single-crystal silicon; a fracture mechanics and non-destructive evaluation investigation of the subcritical-fracture process in rock; slow crack growth in sintered silicon nitride; uniaxial tensile fatigue testing of sintered silicon carbide under cyclic temperature change; and effect of surface corrosion on glass fracture

  17. a Predictive Model of Permeability for Fractal-Based Rough Rock Fractures during Shear

    Science.gov (United States)

    Huang, Na; Jiang, Yujing; Liu, Richeng; Li, Bo; Zhang, Zhenyu

    This study investigates the roles of fracture roughness, normal stress and shear displacement on the fluid flow characteristics through three-dimensional (3D) self-affine fractal rock fractures, whose surfaces are generated using the modified successive random additions (SRA) algorithm. A series of numerical shear-flow tests under different normal stresses were conducted on rough rock fractures to calculate the evolutions of fracture aperture and permeability. The results show that the rough surfaces of fractal-based fractures can be described using the scaling parameter Hurst exponent (H), in which H = 3 - Df, where Df is the fractal dimension of 3D single fractures. The joint roughness coefficient (JRC) distribution of fracture profiles follows a Gauss function with a negative linear relationship between H and average JRC. The frequency curves of aperture distributions change from sharp to flat with increasing shear displacement, indicating a more anisotropic and heterogeneous flow pattern. Both the mean aperture and permeability of fracture increase with the increment of surface roughness and decrement of normal stress. At the beginning of shear, the permeability increases remarkably and then gradually becomes steady. A predictive model of permeability using the mean mechanical aperture is proposed and the validity is verified by comparisons with the experimental results reported in literature. The proposed model provides a simple method to approximate permeability of fractal-based rough rock fractures during shear using fracture aperture distribution that can be easily obtained from digitized fracture surface information.

  18. 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.

  19. Geological discrete-fracture network model (version 1) for the Olkiluoto site, Finland

    International Nuclear Information System (INIS)

    Fox, A.; Buoro, A.; Dahlbo, K.; Wiren, L.

    2009-10-01

    This report describes the methods, analyses, and conclusions of the modelling team in the production of a discrete-fracture network (DFN) model for the Olkiluoto Site in Finland. The geological DFN is a statistical model for stochastically simulating rock fractures and minor faults at a scale ranging from approximately 0.05 m to approximately 500 m; an upper scale limit is not expressly defined, but the DFN model explicitly excludes structures at deformation-zone scales (∼ 500 m) and larger. The DFN model is presented as a series of tables summarizing probability distributions for several parameters necessary for fracture modelling: fracture orientation, fracture size, fracture intensity, and associated spatial constraints. The geological DFN is built from data collected during site characterization (SC) activities at Olkiluoto, which is currently planned to function as a final deep geological repository for spent fuel and nuclear waste from the Finnish nuclear power program. Data used in the DFN analyses include fracture maps from surface outcrops and trenches (as of July 2007), geological and structural data from cored boreholes (as of July 2007), and fracture information collected during the construction of the main tunnels and shafts at the ONKALO laboratory (January 2008). The modelling results suggest that the rock volume at Olkiluoto surrounding the ONKALO tunnel can be separated into three distinct volumes (fracture domains): an upper block, an intermediate block, and a lower block. The three fracture domains are bounded horizontally and vertically by large deformation zones. Fracture properties, such as fracture orientation and relative orientation set intensity, vary between fracture domains. The rock volume at Olkiluoto is dominated by three distinct fracture sets: subhorizontally-dipping fractures striking north-northeast and dipping to the east, a subvertically-dipping fracture set striking roughly north-south, and a subverticallydipping fracture set

  20. Borehole imaging tool detects well bore fractures

    International Nuclear Information System (INIS)

    Ma, T.A.; Bigelow, E.L.

    1993-01-01

    This paper reports on borehole imaging data which can provide high quality geological and petrophysical information to improve fracture identification, dip computations, and lithology determinations in a well bore. The ability to visually quantify the area of a borehole wall occupied by fractures and vugs enhances reservoir characterization and well completion operations. The circumferential borehole imaging log (CBIL) instrument is an acoustic logging device designed to produce a map of the entire borehole wall. The visual images can confirm computed dips and the geological features related to dip. Borehole geometry, including breakout, are accurately described by complete circumferential caliper measurements, which is important information for drilling and completion engineers. In may reservoirs, the images can identify porosity type, bedding characteristics, and petrophysical parameters

  1. Elastic-plastic fracture mechanics of compact bone

    Science.gov (United States)

    Yan, Jiahau

    Bone is a composite composed mainly of organics, minerals and water. Most studies on the fracture toughness of bone have been conducted at room temperature. Considering that the body temperature of animals is higher than room temperature, and that bone has a high volumetric percentage of organics (generally, 35--50%), the effect of temperature on fracture toughness of bone should be studied. Single-edged V-shaped notched (SEVN) specimens were prepared to measure the fracture toughness of bovine femur and manatee rib in water at 0, 10, 23, 37 and 50°C. The fracture toughness of bovine femur and manatee rib were found to decrease from 7.0 to 4.3 MPa·m1/2 and from 5.5 to 4.1 MPa·m1/2, respectively, over a temperature range of 50°C. The decreases were attributed to inability of the organics to sustain greater stresses at higher temperatures. We studied the effects of water and organics on fracture toughness of bone using water-free and organics-free SEVN specimens at 23°C. Water-free and organics-free specimens were obtained by placing fresh bone specimen in a furnace at different temperatures. Water and organics significantly affected the fracture toughness of bone. Fracture toughness of the water-free specimens was 44.7% (bovine femur) and 32.4% (manatee rib) less than that of fresh-bone specimens. Fracture toughness of the organics-free specimens was 92.7% (bovine femur) and 91.5% (manatee rib) less than that of fresh bone specimens. Linear Elastic Fracture Mechanics (LEFM) is widely used to study bone. However, bone often has small to moderate scale yielding during testing. We used J integral, an elastic-plastic fracture-mechanics parameter, to study the fracture process of bone. The J integral of bovine femur increased from 6.3 KJ/mm2 at 23°C to 6.7 KJ/mm2 at 37°C. Although the fracture toughness of bovine bone decreases as the temperature increases, the J integral results show a contrary trend. The energy spent in advancing the crack beyond the linear

  2. FRACTURE SHAFT HUMERUS: INTERLOCKING

    Directory of Open Access Journals (Sweden)

    Deepak Kaladagi

    2014-12-01

    Full Text Available BACKGROUND: The incidence of humeral fracture has significantly increased during the present years due to the population growth and road traffic, domestic, industrial, automobile accidents & disasters like tsunami, earthquakes, head-on collisions, polytrauma etc. In order to achieve a stable fixation followed by early mobilization, numerous surgical implants have been devised. PURPOSE: The purpose of this study is to analyze the results of intramedullary fixation of proximal 2/3rd humeral shaft fractures using an unreamed interlocking intramedullary nail. INTRODUCTION: In 40 skeletally matured patients with fracture shaft of humerus admitted in our hospital, we used unreamed antegrade interlocking nails. MATERIAL: We carried out a prospective analysis of 40 patients randomly selected between 2001 to 2014 who were operated at JNMC Belgaum, MMC Mysore & Navodaya Medical College, Raichur. All cases were either RTAs, Domestic, Industrial, automobile accidents & also other modes of injury. METHOD: Routine investigations with pre-anaesthetic check-up & good quality X-rays of both sides of humerus was taken. Time of surgery ranged from 5-10 days from the time of admission. Only upper 1/3rd & middle 1/3rd humeral shaft fractures were included in the study. In all the cases antegrade locked unreamed humeral nails were inserted under C-arm. Patient was placed in supine position & the shoulder was kept elevated by placing a sandbag under the scapula. In all patients incision taken from tip of acromion to 3cm over deltoid longitudinally. Postoperatively sling applied with wrist & shoulder movements started after 24 hours. All the patients ranged between the age of 21-50 years. RESULTS: Total 40 patients were operated. Maximum fracture site were in the middle third- 76%, 14% upper 1/3rd. All 40 patients achieved union. The average time of union was 8-10 weeks. All patients regained full range of movements except in few cases, where there was shoulder

  3. Pelvic and acetabular fractures

    International Nuclear Information System (INIS)

    Mears, D.C.; Rubash, H.E.

    1986-01-01

    This treatise focuses primarily on the clinical aspects of diagnosis and treatments of pelvic and acetabular fractures. However, considerable attention is also paid to the radiographic diagnosis of trauma and postoperative effects. The book begins with a succinct review of pelvic and acetabular anatomy and pelvic biomechanics. It continues with a radiographic classification of pelvic injury, which will represent the major source of the book's interest for radiologists. The remainder of the book is concerned with clinical management of pelvic and acetabular trauma, including preoperative planning, surgical approaches, techniques of reduction, internal fixation, eternal fixation, post-operative care, and late problems. Even throughout this later portion of the book there are extensive illustrations, including plain radiographs, computed tomographic (CT) scans, reconstructed three-dimensional CT scans, and schematic diagrams of diverse pelvic and acetabular fractures and the elementary surgical techniques for their repair

  4. Investigation of translaminar fracture in fibrereinforced composite laminates---applicability of linear elastic fracture mechanics and cohesive-zone model

    Science.gov (United States)

    Hou, Fang

    With the extensive application of fiber-reinforced composite laminates in industry, research on the fracture mechanisms of this type of materials have drawn more and more attentions. A variety of fracture theories and models have been developed. Among them, the linear elastic fracture mechanics (LEFM) and cohesive-zone model (CZM) are two widely-accepted fracture models, which have already shown applicability in the fracture analysis of fiber-reinforced composite laminates. However, there remain challenges which prevent further applications of the two fracture models, such as the experimental measurement of fracture resistance. This dissertation primarily focused on the study of the applicability of LEFM and CZM for the fracture analysis of translaminar fracture in fibre-reinforced composite laminates. The research for each fracture model consisted of two sections: the analytical characterization of crack-tip fields and the experimental measurement of fracture resistance parameters. In the study of LEFM, an experimental investigation based on full-field crack-tip displacement measurements was carried out as a way to characterize the subcritical and steady-state crack advances in translaminar fracture of fiber-reinforced composite laminates. Here, the fiber-reinforced composite laminates were approximated as anisotropic solids. The experimental investigation relied on the LEFM theory with a modification with respect to the material anisotropy. Firstly, the full-field crack-tip displacement fields were measured by Digital Image Correlation (DIC). Then two methods, separately based on the stress intensity approach and the energy approach, were developed to measure the crack-tip field parameters from crack-tip displacement fields. The studied crack-tip field parameters included the stress intensity factor, energy release rate and effective crack length. Moreover, the crack-growth resistance curves (R-curves) were constructed with the measured crack-tip field parameters

  5. Simulation of Anisotropic Rock Damage for Geologic Fracturing

    Science.gov (United States)

    Busetti, S.; Xu, H.; Arson, C. F.

    2014-12-01

    A continuum damage model for differential stress-induced anisotropic crack formation and stiffness degradation is used to study geologic fracturing in rocks. The finite element-based model solves for deformation in the quasi-linear elastic domain and determines the six component damage tensor at each deformation increment. The model permits an isotropic or anisotropic intact or pre-damaged reference state, and the elasticity tensor evolves depending on the stress path. The damage variable, similar to Oda's fabric tensor, grows when the surface energy dissipated by three-dimensional opened cracks exceeds a threshold defined at the appropriate scale of the representative elementary volume (REV). At the laboratory or wellbore scale (1000m) scales the damaged REV reflects early natural fracturing (background or tectonic fracturing) or shear strain localization (fault process zone, fault-tip damage, etc.). The numerical model was recently benchmarked against triaxial stress-strain data from laboratory rock mechanics tests. However, the utility of the model to predict geologic fabric such as natural fracturing in hydrocarbon reservoirs was not fully explored. To test the ability of the model to predict geological fracturing, finite element simulations (Abaqus) of common geologic scenarios with known fracture patterns (borehole pressurization, folding, faulting) are simulated and the modeled damage tensor is compared against physical fracture observations. Simulated damage anisotropy is similar to that derived using fractured rock-mass upscaling techniques for pre-determined fracture patterns. This suggests that if model parameters are constrained with local data (e.g., lab, wellbore, or reservoir domain), forward modeling could be used to predict mechanical fabric at the relevant REV scale. This reference fabric also can be used as the starting material property to pre-condition subsequent deformation or fluid flow. Continuing efforts are to expand the present damage

  6. Quality of Postoperative Pain Management After Maxillofacial Fracture Repair.

    Science.gov (United States)

    Peisker, Andre; Meissner, Winfried; Raschke, Gregor F; Fahmy, Mina D; Guentsch, Arndt; Schiller, Juliane; Schultze-Mosgau, Stefan

    2018-05-01

    Effective pain management is an essential component in the perioperative care of surgical patients. However, postoperative pain after maxillofacial fracture repair and its optimal therapy has not been described in detail. In a prospective cohort study, 95 adults rated their pain on the first postoperative day after maxillofacial fracture repair using the questionnaire of the Quality Improvement in Postoperative Pain Management (QUIPS) project. Quality Improvement in Postoperative Pain Management allowed for a standardized assessment of patients' characteristics and pain-related parameters. Overall, the mean maximal pain and pain on activity (numeric rating scales) were significantly higher in patients with mandibular fractures than in patients with midface fractures (P = 0.002 and P = 0.045, respectively). In patients with mandibular fractures, a longer duration of surgery was significantly associated with higher satisfaction with pain intensity (P = 0.015), but was more frequently associated with postoperative vomiting (P = 0.023). A shorter duration of surgery and an absence of preoperative pain counseling in these patients were significantly correlated to desire for more pain medication (P = 0.049 and P = 0.004, respectively). Patients with mandibular fractures that received opioids in the recovery room had significantly higher strain-related pain (P = 0.017). In patients with midface fractures, a longer duration of surgery showed significantly higher levels of decreased mobility (P = 0.003). Patients receiving midazolam for premedication had significantly less minimal pain (P = 0.021). Patients with mandibular fractures seem to have more postoperative pain than patients with midface fractures. Monitoring of postsurgical pain and a procedure-specific pain-treatment protocol should be performed in clinical routine.

  7. Statistical fracture mechanics approach to the strength of brittle rock

    International Nuclear Information System (INIS)

    Ratigan, J.L.

    1981-06-01

    Statistical fracture mechanics concepts used in the past for rock are critically reviewed and modifications are proposed which are warranted by (1) increased understanding of fracture provided by modern fracture mechanics and (2) laboratory test data both from the literature and from this research. Over 600 direct and indirect tension tests have been performed on three different rock types; Stripa Granite, Sierra White Granite and Carrara Marble. In several instances assumptions which are common in the literature were found to be invalid. A three parameter statistical fracture mechanics model with Mode I critical strain energy release rate as the variant is presented. Methodologies for evaluating the parameters in this model as well as the more commonly employed two parameter models are discussed. The experimental results and analysis of this research indicate that surfacially distributed flaws, rather than volumetrically distributed flaws are responsible for rupture in many testing situations. For several of the rock types tested, anisotropy (both in apparent tensile strength and size effect) precludes the use of contemporary statistical fracture mechanics models

  8. Treatment of unstable trochanteric fractures : the balance between man and material

    NARCIS (Netherlands)

    I.B. Schipper (Inger)

    2003-01-01

    textabstractTreatment of unstable trochanteric fractures poses a challenge to surgeons in many ways. Accepting this challenge requires understanding of those parameters that determine the outcome. In operative fracture care at least four elements influence the outcome of treatment: the patient, the

  9. Could whole body vibration exercises influence the risk factors for fractures in women with osteoporosis?

    Directory of Open Access Journals (Sweden)

    Eloá Moreira-Marconi

    2016-12-01

    Conclusions: Although the paucity of research regarding direct effects of WBV in decreasing fractures, WBV could be a feasible and effective way to modify well-recognized risk factors for falls and fractures, improvements in some aspects of neuromuscular function and balance. More studies have to be performed establish protocols with well controlled parameters.

  10. Double segmental tibial fractures - an unusual fracture pattern

    Directory of Open Access Journals (Sweden)

    Bali Kamal

    2012-02-01

    Full Text Available 【Abstract】A case of a 50-year-old pedestrian who was hit by a bike and suffered fractures of both bones of his right leg was presented. Complete clinical and radiographic assessment showed double segmental fractures of the tibia and multisegmental fractures of the fibula. Review of the literature revealed that this fracture pattern was unique and only a single case was reported so far. Moreover, we discussed the possible mechanisms which can lead to such an injury. We also discussed the management of segmental tibial fracture and the difficulties encountered with them. This case was managed by modern osteosynthesis tech- nique with a pleasing outcome. Key words: Fracture, bone; Tibia; Fibula; Nails

  11. Numerical investigation and optimization of multiple fractures in tight gas reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Hou, M.Z. [Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany). ITE; Energie-Forschungszentrum Niedersachsen, Goslar (Germany); Zhou, L. [Energie-Forschungszentrum Niedersachsen, Goslar (Germany)

    2013-08-01

    The main objective of the project DGMK-680 in phase 2 was to investigate the influence of fractures on each other in a multi-fracture system including their space optimization by using the numerical program FLAC3D with our own developments, which treats all fractures in one 3D geometric model under 3D stress state with fully hydro-mechanical coupling effect. The case study was conducted on a horizontal wellbore at location A, which was stimulated hydraulically with a total of eight transverse fractures in summer 2009. Transverse multiple fractures were simulated using the modified continuum method. In the simulation all fractures were generated in one single model, comprising 22 different rock layers. Each layer was assumed to be homogeneous with regard to its rock and hydromechanical parameters. Thus the influence of the individual fractures on each other can be investigated. The simulation procedure applied, which is a consecutive execution ofa hydraulic and a mechanical computation, is the same for all fractures. The only differences are the primary in-situ stresses, the initial pore pressure, the injection parameters (location, rate, volume, duration), which lead to different patterns of fracture propagations. But there are still some common points, such as irregular patterns of the fracture front, which represents the heterogeneity of the model. All fractures (1 to 8) have their fracture average half-length between 70 m to 115 m, height between 93 m to 114 m and average width between 18 mm to 31 mm. The percentage difference of fracture height for individual fractures is obviously smaller than that of the fracture half-lengths, because the fracture barriers at bottom and top limit the fracture propagation in z-direction. Incomparison with the analytical simulator (FracPro) most results match well. Simulation of multiple fractures at location A, with the newly developed algorithms, shows that individual transverse multiple fractures at distances between 100

  12. Bomb parameters

    International Nuclear Information System (INIS)

    Kerr, George D.; Young, Rebert W.; Cullings, Harry M.; Christry, Robert F.

    2005-01-01

    The reconstruction of neutron and gamma-ray doses at Hiroshima and Nagasaki begins with a determination of the parameters describing the explosion. The calculations of the air transported radiation fields and survivor doses from the Hiroshima and Nagasaki bombs require knowledge of a variety of parameters related to the explosions. These various parameters include the heading of the bomber when the bomb was released, the epicenters of the explosions, the bomb yields, and the tilt of the bombs at time of explosion. The epicenter of a bomb is the explosion point in air that is specified in terms of a burst height and a hypocenter (or the point on the ground directly below the epicenter of the explosion). The current reassessment refines the energy yield and burst height for the Hiroshima bomb, as well as the locations of the Hiroshima and Nagasaki hypocenters on the modern city maps used in the analysis of the activation data for neutrons and TLD data for gamma rays. (J.P.N.)

  13. FRACTURED PETROLEUM RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Abbas Firoozabadi

    1999-06-11

    The four chapters that are described in this report cover a variety of subjects that not only give insight into the understanding of multiphase flow in fractured porous media, but they provide also major contribution towards the understanding of flow processes with in-situ phase formation. In the following, a summary of all the chapters will be provided. Chapter I addresses issues related to water injection in water-wet fractured porous media. There are two parts in this chapter. Part I covers extensive set of measurements for water injection in water-wet fractured porous media. Both single matrix block and multiple matrix blocks tests are covered. There are two major findings from these experiments: (1) co-current imbibition can be more efficient than counter-current imbibition due to lower residual oil saturation and higher oil mobility, and (2) tight fractured porous media can be more efficient than a permeable porous media when subjected to water injection. These findings are directly related to the type of tests one can perform in the laboratory and to decide on the fate of water injection in fractured reservoirs. Part II of Chapter I presents modeling of water injection in water-wet fractured media by modifying the Buckley-Leverett Theory. A major element of the new model is the multiplication of the transfer flux by the fractured saturation with a power of 1/2. This simple model can account for both co-current and counter-current imbibition and computationally it is very efficient. It can be orders of magnitude faster than a conventional dual-porosity model. Part II also presents the results of water injection tests in very tight rocks of some 0.01 md permeability. Oil recovery from water imbibition tests from such at tight rock can be as high as 25 percent. Chapter II discusses solution gas-drive for cold production from heavy-oil reservoirs. The impetus for this work is the study of new gas phase formation from in-situ process which can be significantly

  14. Innovations in the management of hip fractures.

    Science.gov (United States)

    Teasdall, Robert D; Webb, Lawrence X

    2003-08-01

    Hip fractures include fractures of the head, neck, intertrochanteric, and subtrochanteric regions. Head fractures commonly accompany dislocations. Neck fractures and intertrochanteric fractures occur with greatest frequency in elderly patients with a low bone mineral density and are produced by low-energy mechanisms. Subtrochanteric fractures occur in a predominantly strong cortical osseous region that is exposed to large compressive stresses. Implants used to address these fractures must accommodate significant loads while the fractures consolidate. Complications secondary to hip fractures produce significant morbidity and include infection, nonunion, malunion, decubitus ulcers, fat emboli, deep venous thrombosis, pulmonary embolus, pneumonia, myocardial infarction, stroke, and death.

  15. An approach to ductile fracture resistance modelling in pipeline steels

    Energy Technology Data Exchange (ETDEWEB)

    Pussegoda, L.N.; Fredj, A. [BMT Fleet Technology Ltd., Kanata (Canada)

    2009-07-01

    Ductile fracture resistance studies of high grade steels in the pipeline industry often included analyses of the crack tip opening angle (CTOA) parameter using 3-point bend steel specimens. The CTOA is a function of specimen ligament size in high grade materials. Other resistance measurements may include steady state fracture propagation energy, critical fracture strain, and the adoption of damage mechanisms. Modelling approaches for crack propagation were discussed in this abstract. Tension tests were used to calibrate damage model parameters. Results from the tests were then applied to the crack propagation in a 3-point bend specimen using modern 1980 vintage steels. Limitations and approaches to overcome the difficulties associated with crack propagation modelling were discussed.

  16. Derivation of Path Independent Coupled Mix Mode Cohesive Laws from Fracture Resistance Curves

    DEFF Research Database (Denmark)

    Goutianos, Stergios

    2016-01-01

    A generalised approach is presented to derive coupled mixed mode cohesive laws described with physical parameters such as peak traction, critical opening, fracture energy and cohesive shape. The approach is based on deriving mix mode fracture resistance curves from an effective mix mode cohesive...... law at different mode mixities. From the fracture resistance curves, the normal and shear stresses of the cohesive laws can be obtained by differentiation. Since, the mixed mode cohesive laws are obtained from a fracture resistance curve (potential function), path independence is automatically...

  17. Determination of fracture toughness of human permanent and primary enamel using an indentation microfracture method.

    Science.gov (United States)

    Hayashi-Sakai, Sachiko; Sakai, Jun; Sakamoto, Makoto; Endo, Hideaki

    2012-09-01

    The purpose of the present study was to examine the fracture toughness and Vickers microhardness number of permanent and primary human enamel using the indentation microfracture method. Crack resistance and a parameter indirectly related to fracture toughness were measured in 48 enamel specimens from 16 permanent teeth and 12 enamel specimens obtained from six primary teeth. The Vickers microhardness number of the middle portion was greater than the upper portion in primary enamel. The fracture toughness was highest in the middle portion of permanent enamel, because fracture toughness greatly depends upon microstructure. These findings suggest that primary teeth are not miniature permanent teeth but have specific and characteristic mechanical properties.

  18. Low-density lipoprotein cholesterol is associated with fracture risk in diabetes patients - a nested case-control study

    DEFF Research Database (Denmark)

    Starup-Linde, Jakob; Gregersen, Søren; Vestergaard, Peter

    2014-01-01

    available for an analysis of patient characteristics, co-morbidities, biochemical parameters and drug usage. Results: Patient age at the time of diabetes diagnosis, a diagnosis of previous fracture, an alcohol related diagnosis, total cholesterol level, and the usage of antidepressants, antiepileptics...... and insulin all increased the odds of fracture. Low-density lipoprotein cholesterol (LDL) levels decreased the odds of fracture, where the level of 3.04-5.96 mmol/l was optimal with regard to fracture risk. Conclusion: LDL may add to the understanding of fractures in diabetes patients and it may be added...

  19. Characterisation of fracture network and groundwater preferential ...

    African Journals Online (AJOL)

    Characterisation of fractured rocks and evaluation of fracture connectivity are essential for the study of subsurface flow and transport in fractured rock aquifers. In this study, we use a new method to present fracture networks and analyse the connectivity of the fractures, based on the technique of randomly-generated ...

  20. On size effects in fracture

    International Nuclear Information System (INIS)

    Sinclair, G.B.

    1985-01-01

    This paper discusses the dependence of fracture stress on size. This conclusion is based on classical energy arguments. For an in-plane scaled specimen pair, the larger the specimen the smaller the fracture stress. In contrast the same theory gives a different dependence for out-of-plane specimen and the dependence involves plane stress, strain, fracture stresses and Poisson's ratio. The objective of this paper is to examine how well these predictions are actually complied with

  1. Overview of Mandibular Condyle Fracture

    OpenAIRE

    Park, Su-Seong; Lee, Keun-Cheol; Kim, Seok-Kwun

    2012-01-01

    The mandibular condyle is a region that plays a key role in the opening and closing of the mouth, and because fracture causes functional and aesthetic problems such as facial asymmetry, it is very important to perform accurate reduction. Traditionally, there has been disagreement on how to manage fracture of the mandibular condyle. This review explores the misunderstanding of mandibular condyle fracture treatment and modern-day treatment strategies.

  2. Overview of Mandibular Condyle Fracture

    Directory of Open Access Journals (Sweden)

    Su-Seong Park

    2012-07-01

    Full Text Available The mandibular condyle is a region that plays a key role in the opening and closing of the mouth, and because fracture causes functional and aesthetic problems such as facial asymmetry, it is very important to perform accurate reduction. Traditionally, there has been disagreement on how to manage fracture of the mandibular condyle. This review explores the misunderstanding of mandibular condyle fracture treatment and modern-day treatment strategies.

  3. Overview of Mandibular Condyle Fracture

    Directory of Open Access Journals (Sweden)

    Su-Seong Park

    2012-07-01

    Full Text Available The mandibular condyle is a region that plays a key role in the opening and closing ofthe mouth, and because fracture causes functional and aesthetic problems such as facialasymmetry, it is very important to perform accurate reduction. Traditionally, there has beendisagreement on how to manage fracture of the mandibular condyle. This review exploresthe misunderstanding of mandibular condyle fracture treatment and modern-day treatmentstrategies.

  4. Golfer's fracture of the ribs

    International Nuclear Information System (INIS)

    Lim, J. H.

    1980-01-01

    Golfer's fracture is stress fracture of the posterior portion of left 3, 4, 5, 6 or 7th ribs of golfer's, usually beginners,and it is considered due to exposure to unaccustomed severe exercise of this fascinating sport. Healing is usually uneventful, but possible complication may occur, because symptom is mild and golfers continue the exercise with physical therapy such as massage. Author report 4 cases of golfer's fracture, including 1 case complicated by platelike at electasis of lung.

  5. Golfer's fracture of the ribs

    Energy Technology Data Exchange (ETDEWEB)

    Lim, J H [Seoul District Armed Forces General Hospital, Seoul (Korea, Republic of)

    1980-06-15

    Golfer's fracture is stress fracture of the posterior portion of left 3, 4, 5, 6 or 7th ribs of golfer's, usually beginners,and it is considered due to exposure to unaccustomed severe exercise of this fascinating sport. Healing is usually uneventful, but possible complication may occur, because symptom is mild and golfers continue the exercise with physical therapy such as massage. Author report 4 cases of golfer's fracture, including 1 case complicated by platelike at electasis of lung.

  6. Torsion fracture of carbon nanocoils

    Science.gov (United States)

    Yonemura, Taiichiro; Suda, Yoshiyuki; Tanoue, Hideto; Takikawa, Hirofumi; Ue, Hitoshi; Shimizu, Kazuki; Umeda, Yoshito

    2012-10-01

    We fix a carbon nanocoil (CNC) on a substrate in a focused ion beam instrument and then fracture the CNC with a tensile load. Using the CNC spring index, we estimate the maximum to average stress ratio on the fractured surface to range from 1.3 to 1.7, indicating stress concentration on the coil wire inner edge. Scanning electron microscopy confirms a hollow region on the inner edge of all fractured surfaces.

  7. Tracer Testing for Estimating Heat Transfer Area in Fractured Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Pruess, Karsten; van Heel, Ton; Shan, Chao

    2004-05-12

    A key parameter governing the performance and life-time of a Hot Fractured Rock (HFR) reservoir is the effective heat transfer area between the fracture network and the matrix rock. We report on numerical modeling studies into the feasibility of using tracer tests for estimating heat transfer area. More specifically, we discuss simulation results of a new HFR characterization method which uses surface-sorbing tracers for which the adsorbed tracer mass is proportional to the fracture surface area per unit volume. Sorption in the rock matrix is treated with the conventional formulation in which tracer adsorption is volume-based. A slug of solute tracer migrating along a fracture is subject to diffusion across the fracture walls into the adjacent rock matrix. Such diffusion removes some of the tracer from the fluid in the fractures, reducing and retarding the peak in the breakthrough curve (BTC) of the tracer. After the slug has passed the concentration gradient reverses, causing back-diffusion from the rock matrix into the fracture, and giving rise to a long tail in the BTC of the solute. These effects become stronger for larger fracture-matrix interface area, potentially providing a means for estimating this area. Previous field tests and modeling studies have demonstrated characteristic tailing in BTCs for volatile tracers in vapor-dominated reservoirs. Simulated BTCs for solute tracers in single-phase liquid systems show much weaker tails, as would be expected because diffusivities are much smaller in the aqueous than in the gas phase, by a factor of order 1000. A much stronger signal of fracture-matrix interaction can be obtained when sorbing tracers are used. We have performed simulation studies of surface-sorbing tracers by implementing a model in which the adsorbed tracer mass is assumed proportional to the fracture-matrix surface area per unit volume. The results show that sorbing tracers generate stronger tails in BTCs, corresponding to an effective

  8. CHARACTERIZATION OF IN-SITU STRESS AND PERMEABILITY IN FRACTURED RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Daniel R. Burns; M. Nafi Toksoz

    2004-07-19

    regular, discrete, vertical fracture systems. The model contains a series of point scatterers delineating the top tip and bottom tip of each vertical fracture. When the shot record is located in the middle of the fractured zone and oriented normal to the direction of fracturing, a complicated series of beating is observed in the back scattered energy. When the shot record is oriented parallel to the fracturing, ringing wavetrains are observed with moveouts similar to reflections from many horizontal layers. These results are consistent with the full 3D elastic modeling results. An AVOA analysis method was refined and applied to a field data set. An iterative, nonlinear least squares inversion that uses the Gauss-Newton method and analyzes the full range of azimuths simultaneously was employed. Resulting fracture location and strike orientation estimates are consistent with other fracture information from the area. Two modeling approaches for estimating permeability values from seismically derived fracture parameters have been investigated. The first is a statistical method that calculates the permeability tensor for a given distribution of fractures. A possible workflow using this method was tested on fracture distributions obtained from the Transfer Function-Scattering Index analysis method. Fracture aperture and length estimates are needed for this method. The second method is a direct flow model of discrete fractures and fracture networks using a computational fluid dynamics code. This tool provides a means of visualizing flow in fracture networks and comparing expressions for equivalent fracture aperture flow to the actual flow. A series of two dimensional models of fractures and fracture networks, as well as a 3-D model of a single rough fracture, were tested.

  9. Clavicular fractures: Classification, diagnosis, therapy

    International Nuclear Information System (INIS)

    Schunk, K.; Strunk, H.; Schild, H.; Lohr, S.

    1988-01-01

    Clavicular fracture is one of the most frequent skeletal lesions. In most cases the median third of the clavicula is affected (this is due to the peculiar biomechanical structure). Accompanying lesions and complications of clavicular fractures are rare. A total of 13 X-ray diagnostic techniques are described of clavicular fractures. X-ray film should, as a matter of principle, always be taken in two planes. Definitely the major part of clavicular fractures are treated conservatively (rucsac dressing), whereas surgery is reserved for few and strictly defined indications. (orig.) [de

  10. [Intramedullary stabilisation of clavicula fractures].

    Science.gov (United States)

    Prokop, A; Schiffer, G; Jubel, A; Chmielnicki, M

    2013-10-01

    With an incidence of 64/100,000, clavicular shaft fractures are one of the most common fractures. Intramedullary fixation with Prevot nails was initially reported in the late 1990s. This procedure offers minimally invasive stabilization of the fracture, thus enabling immediate mobilization and rapid loading capacity. Using a case study, the positioning and procedure are demonstrated on video. The intramedullary implant accommodates the varying tension loading of the clavicle. This treatment is ideal for clavicular fractures with 2-3 fragments. Compared to patients treated conservatively, operated patients achieve more rapid and improved mobility. Employment disability is shorter, and malunion occurs less frequently. Georg Thieme Verlag KG Stuttgart · New York.

  11. Clavicular fractures: Classification, diagnosis, therapy

    Energy Technology Data Exchange (ETDEWEB)

    Schunk, K.; Strunk, H.; Schild, H.; Lohr, S.

    1988-09-01

    Clavicular fracture is one of the most frequent skeletal lesions. In most cases the median third of the clavicula is affected (this is due to the peculiar biomechanical structure). Accompanying lesions and complications of clavicular fractures are rare. A total of 13 X-ray diagnostic techniques are described of clavicular fractures. X-ray film should, as a matter of principle, always be taken in two planes. Definitely the major part of clavicular fractures are treated conservatively (rucsac dressing), whereas surgery is reserved for few and strictly defined indications.

  12. Management of civilian ballistic fractures.

    Science.gov (United States)

    Seng, V S; Masquelet, A C

    2013-12-01

    The management of ballistic fractures, which are open fractures, has often been studied in wartime and has benefited from the principles of military surgery with debridement and lavage, and the use of external fixation for bone stabilization. In civilian practice, bone stabilization of these fractures is different and is not performed by external fixation. Fifteen civilian ballistic fractures, Gustilo II or IIIa, two associated with nerve damage and none with vascular damage, were reviewed. After debridement and lavage, ten internal fixations and five conservative treatments were used. No superficial or deep surgical site infection was noted. Fourteen of the 15 fractures (93%) healed without reoperation. Eleven of the 15 patients (73%) regained normal function. Ballistic fractures have a bad reputation due to their many complications, including infections. In civilian practice, the use of internal fixation is not responsible for excessive morbidity, provided debridement and lavage are performed. Civilian ballistic fractures, when they are caused by low-velocity firearms, differ from military ballistic fractures. Although the principle of surgical debridement and lavage remains the same, bone stabilization is different and is similar to conventional open fractures. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  13. Rehabilitation after falls and fractures.

    Science.gov (United States)

    Dionyssiotis, Y; Dontas, I A; Economopoulos, D; Lyritis, G P

    2008-01-01

    Falls are one of the most common geriatric problems threatening the independence of older persons. Elderly patients tend to fall more often and have a greater tendency to fracture their bones. Fractures occur particularly in osteoporotic people due to increased bone fragility, resulting in considerable reduction of quality of life, morbidity, and mortality. This article provides information for the rehabilitation of osteoporotic fractures pertaining to the rehabilitation of the fractured patient, based on personal experience and literature. It also outlines a suggested effective and efficient clinical strategy approach for preventing falls in individual patients.

  14. A newborn with multiple fractures

    International Nuclear Information System (INIS)

    Kantorova, E.; Kratky, L.; Nevsimal, I.; Marik, K.; Kozlowski, K.

    2008-01-01

    Sometimes newborns with multiple fractures are diagnosed as osteogenesis imperfecta in spite of absence of radiographic findings supporting this diagnosis. A newborn with multiple fractures was diagnosed as osteogenesis imperfecta. Analysis of the structure of the long bones, pattern of fractures and poorly developed muscles suggested the diagnosis of fetal akinesia deformation syndrome. This was confirmed by pregnancy history and clinical findings. Multiple fractures in a newborn may present with diagnostic radiographic features as in osteogenesis imperfecta, or as in lethal gracile bone dysplasias or achondrogenesis type IA. If those features are absent, other diseases should be considered. Radiographs should be compared with pregnancy history and clinical findings in the newborn. (authors)

  15. Hydraulic properties of fracture networks

    International Nuclear Information System (INIS)

    Dreuzy, J.R. de

    1999-12-01

    Fractured medium are studied in the general framework of oil and water supply and more recently for the underground storage of high level nuclear wastes. As fractures are generally far more permeable than the embedding medium, flow is highly channeled in a complex network of fractures. The complexity of the network comes from the broad distributions of fracture length and permeability at the fracture scale and appears through the increase of the equivalent permeability at the network scale. The goal of this thesis is to develop models of fracture networks consistent with both local-scale and global-scale observations. Bidimensional models of fracture networks display a wide variety of flow structures ranging from the sole permeable fracture to the equivalent homogeneous medium. The type of the relevant structure depends not only on the density and the length and aperture distributions but also on the observation scale. In several models, a crossover scale separates complex structures highly channeled from more distributed and homogeneous-like flow patterns at larger scales. These models, built on local characteristics and validated by global properties, have been settled in steady state. They have also been compared to natural well test data obtained in Ploemeur (Morbihan) in transient state. The good agreement between models and data reinforces the relevance of the models. Once validated and calibrated, the models are used to estimate the global tendencies of the main flow properties and the risk associated with the relative lack of data on natural fractures media. (author)

  16. 3D Simulation of Multiple Simultaneous Hydraulic Fractures with Different Initial Lengths in Rock

    Science.gov (United States)

    Tang, X.; Rayudu, N. M.; Singh, G.

    2017-12-01

    Hydraulic fracturing is widely used technique for extracting shale gas. During this process, fractures with various initial lengths are induced in rock mass with hydraulic pressure. Understanding the mechanism of propagation and interaction between these induced hydraulic cracks is critical for optimizing the fracking process. In this work, numerical results are presented for investigating the effect of in-situ parameters and fluid properties on growth and interaction of multi simultaneous hydraulic fractures. A fully coupled 3D fracture simulator, TOUGH- GFEM is used for simulating the effect of different vital parameters, including in-situ stress, initial fracture length, fracture spacing, fluid viscosity and flow rate on induced hydraulic fractures growth. This TOUGH-GFEM simulator is based on 3D finite volume method (FVM) and partition of unity element method (PUM). Displacement correlation method (DCM) is used for calculating multi - mode (Mode I, II, III) stress intensity factors. Maximum principal stress criteria is used for crack propagation. Key words: hydraulic fracturing, TOUGH, partition of unity element method , displacement correlation method, 3D fracturing simulator

  17. Fracture network growth for prediction of fracture characteristics and connectivity in tight reservoir rocks

    NARCIS (Netherlands)

    Barnhoorn, A.; Cox, S.F.

    2012-01-01

    Fracturing experiments on very low-porosity dolomite rocks shows a difference in growth of fracture networks by stress-driven fracturing and fluid-driven fracturing. Stress-driven fracture growth, in the absence of fluid pressure, initially forms fractures randomly throughout the rocks followed by

  18. Corroboration of mechanoregulatory algorithms for tissue differentiation during fracture healing: comparison with in vivo results

    NARCIS (Netherlands)

    Isaksson, H.E.; Donkelaar, van C.C.; Huiskes, R.; Ito, K.

    2006-01-01

    Several mechanoregulation algorithms proposed to control tissue differentiation during bone healing have been shown to accurately predict temporal and spatial tissue distributions during normal fracture healing. As these algorithms are different in nature and biophysical parameters, it raises the

  19. The brush model - a new approach to numerical modeling of matrix diffusion in fractured clay stone

    International Nuclear Information System (INIS)

    Lege, T.; Shao, H.

    1998-01-01

    A special approach for numerical modeling of contaminant transport in fractured clay stone is presented. The rock matrix and the fractures are simulated with individual formulations for FE grids and transport, coupled into a single model. The capacity of the rock matrix to take up contaminants is taken into consideration with a discrete simulation of matrix diffusion. Thus, the natural process of retardation due to matrix diffusion can be better simulated than by a standard introduction of an empirical parameter into the transport equation. Transport in groundwater in fractured clay stone can be simulated using a model called a 'brush model'. The 'brush handle' is discretized by 2-D finite elements. Advective-dispersive transport in groundwater in the fractures is assumed. The contaminant diffuses into 1D finite elements perpendicular to the fractures, i.e., the 'bristles of the brush'. The conclusion is drawn that matrix diffusion is an important property of fractured clay stone for contaminant retardation. (author)

  20. Heavy crude production from shallow formations: long horizontal wells versus horizontal fractures

    Energy Technology Data Exchange (ETDEWEB)

    Valko, P.; Economides, M. J. [Texas A and M Univ., TX (United States)

    1998-12-31

    The feasibility of producing heavy oil from shallow formations using either horizontal wells or short horizontal wells fractured horizontally is demonstrated. The problem of optimum proppant placement is solved in two steps. In step one, the finite productivity performance is considered in general terms showing that the performance is a function of two dimensionless parameters. Following derivation of optimum conditions, the solution is applied to the horizontal fracture consideration. The limiting factor is that to create an effective finite conductivity fracture, the dimensionless fracture conductivity must be on the order of unity, a fracture that is difficult to realize in higher permeability formations. The best candidates for the suggested configuration are shallow or moderate formations, or formations otherwise proven to accept horizontal fractures, and formations with low permeability/viscosity ratio. 7 refs., 2 tabs., 10 figs., 2 appendices.

  1. Contribution to the research on fracture properties of metals in the elasto-plastic field

    International Nuclear Information System (INIS)

    Rousselier, G.; Electricite de France, 77 - Ecuelles. Dept. Etudes des Materiaux)

    1979-01-01

    Standard Fracture Mechanics theories proved unsuccessful for the treatment of ductile fracture in metals. We have shown the necessity of better knowledge and satisfactory modelling of the fracture process, prior to any application to cracked bodies. In that way we developed stress-strain laws which take into consideration the growth of voids during ductile fracture. The damage resulting from void growth is characterized by internal parameters. Finite strain analysis leads to material instability, corresponding to the stage of void coalescence and material decohesion. This latter result is only true in a finite strain analysis. In the infinitesimal strain finite element numerical analysis of three-point bend specimens, a local fracture criterion is used. The experimental determination of this criterion is performed with axisymmetrical notched tension specimens, which allow the investigation of various stress triaxialities at fracture. The numerical analysis proved effective in the modelling of stable crack growth and size effect, and was compared with experimental results [fr

  2. Crack tip fields and mixed mode fracture behaviour of progressively drawn pearlitic steel

    Directory of Open Access Journals (Sweden)

    J. Toribio

    2015-07-01

    Full Text Available This paper deals with the influence of the cold drawing process on the fracture behaviour of pearlitic steels. To this end, fracture tests under axial loading were performed on steel wires with different drawing degree (from a hot rolled bar to a commercial prestressing steel wire, transversely pre-cracked by fatigue, analyzing in detail the changes in fracture micromechanisms. The deflection angles of the fracture path were measured by longitudinal metallographic sections and the characteristic parameters of the loaddisplacement plot were related to different fracture events. Results allowed a calculation of critical stress intensity factors for different fracture angles and drawing degrees, thus evaluating the strength anisotropy and obtaining a sort of directional toughness.

  3. Statistical evaluation of fracture characteristics of RPV steels in the ductile-brittle transition temperature region

    International Nuclear Information System (INIS)

    Kang, Sung Sik; Chi, Se Hwan; Hong, Jun Hwa

    1998-01-01

    The statistical analysis method was applied to the evaluation of fracture toughness in the ductile-brittle transition temperature region. Because cleavage fracture in steel is of a statistical nature, fracture toughness data or values show a similar statistical trend. Using the three-parameter Weibull distribution, a fracture toughness vs. temperature curve (K-curve) was directly generated from a set of fracture toughness data at a selected temperature. Charpy V-notch impact energy was also used to obtain the K-curve by a K IC -CVN (Charpy V-notch energy) correlation. Furthermore, this method was applied to evaluate the neutron irradiation embrittlement of reactor pressure vessel(RPV) steel. Most of the fracture toughness data were within the 95 percent confidence limits. The prediction of a transition temperature shift by statistical analysis was compared with that from the experimental data. (author)

  4. Instability in dynamic fracture

    Science.gov (United States)

    Fineberg, J.; Marder, M.

    1999-05-01

    The fracture of brittle amorphous materials is an especially challenging problem, because the way a large object shatters is intimately tied to details of cohesion at microscopic scales. This subject has been plagued by conceptual puzzles, and to make matters worse, experiments seemed to contradict the most firmly established theories. In this review, we will show that the theory and experiments fit within a coherent picture where dynamic instabilities of a crack tip play a crucial role. To accomplish this task, we first summarize the central results of linear elastic dynamic fracture mechanics, an elegant and powerful description of crack motion from the continuum perspective. We point out that this theory is unable to make predictions without additional input, information that must come either from experiment, or from other types of theories. We then proceed to discuss some of the most important experimental observations, and the methods that were used to obtain the them. Once the flux of energy to a crack tip passes a critical value, the crack becomes unstable, and it propagates in increasingly complicated ways. As a result, the crack cannot travel as quickly as theory had supposed, fracture surfaces become rough, it begins to branch and radiate sound, and the energy cost for crack motion increases considerably. All these phenomena are perfectly consistent with the continuum theory, but are not described by it. Therefore, we close the review with an account of theoretical and numerical work that attempts to explain the instabilities. Currently, the experimental understanding of crack tip instabilities in brittle amorphous materials is fairly detailed. We also have a detailed theoretical understanding of crack tip instabilities in crystals, reproducing qualitatively many features of the experiments, while numerical work is beginning to make the missing connections between experiment and theory.

  5. 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 ...

  6. Rehabilitation of neglected Monteggia fracture: Dislocations in children.

    Science.gov (United States)

    Yıldırım, Azad; Nas, Kemal

    2017-11-06

    There are limited studies related to the rehabilitation of neglected Monteggia fracture-dislocations. This study reports the results of the rehabilitation of neglected Monteggia fractures and dislocations and the best treatment options available. Thirteen children were rehabilitated between 2009 and 2012. A retrospective chart review was conducted to record the following: age, gender, anatomic region of fractures, time delay from symptom onset to fracture, Bado classification, Mayo Elbow Performance Index (MEPI) which includes pain, range of motion and daily life comfort, surgeries, length of hospitalization, location and pattern of fracture, length of follow-up and complications. The study group included thirteen children and adolescents; eleven males and two females with a mean age of 8.5 (range 2-15) years. According to the Bado classification, 11 patients had type 1, one had type 3 and one had type 4 fracture-dislocations. For Mayo Elbow Performance Index (MEPI) scales, patients that were less than ten years old had greater mean scores. Two patients had superficial infection, one had subluxation, one had osteoarthritis, one had delayed bone union and two had rigidity at the elbow. The goals of elbow rehabilitation following Neglected Monteggia cases include restoring function by restoring motion and muscle performance; influencing scar remodeling and preventing joint contracture; and restoring or maintaining joint stability. Patients aged younger than 10 years and intervals of less than one-year, between trauma and diagnosis, as well as early and effective rehabilitation were found as important parameters regarding favorable outcomes.

  7. Slow Waves in Fractures Filled with Viscous Fluid

    Energy Technology Data Exchange (ETDEWEB)

    Korneev, Valeri

    2008-01-08

    Stoneley guided waves in a fluid-filled fracture generally have larger amplitudes than other waves, and therefore, their properties need to be incorporated in more realistic models. In this study, a fracture is modeled as an infinite layer of viscous fluid bounded by two elastic half-spaces with identical parameters. For small fracture thickness, I obtain a simple dispersion equation for wave-propagation velocity. This velocity is much smaller than the velocity of a fluid wave in a Biot-type solution, in which fracture walls are assumed to be rigid. At seismic prospecting frequencies and realistic fracture thicknesses, the Stoneley guided wave has wavelengths on the order of several meters and an attenuation Q factor exceeding 10, which indicates the possibility of resonance excitation in fluid-bearing rocks. The velocity and attenuation of Stoneley guided waves are distinctly different at low frequencies for water and oil. The predominant role of fractures in fluid flow at field scales is supported by permeability data showing an increase of several orders of magnitude when compared to values obtained at laboratory scales. These data suggest that Stoneley guided waves should be taken into account in theories describing seismic wave propagation in fluid-saturated rocks.

  8. Periodic Hydraulic Testing for Discerning Fracture Network Connections

    Science.gov (United States)

    Becker, M.; Le Borgne, T.; Bour, O.; Guihéneuf, N.; Cole, M.

    2015-12-01

    Discrete fracture network (DFN) models often predict highly variable hydraulic connections between injection and pumping wells used for enhanced oil recovery, geothermal energy extraction, and groundwater remediation. Such connections can be difficult to verify in fractured rock systems because standard pumping or pulse interference tests interrogate too large a volume to pinpoint specific connections. Three field examples are presented in which periodic hydraulic tests were used to obtain information about hydraulic connectivity in fractured bedrock. The first site, a sandstone in New York State, involves only a single fracture at a scale of about 10 m. The second site, a granite in Brittany, France, involves a fracture network at about the same scale. The third site, a granite/schist in the U.S. State of New Hampshire, involves a complex network at scale of 30-60 m. In each case periodic testing provided an enhanced view of hydraulic connectivity over previous constant rate tests. Periodic testing is particularly adept at measuring hydraulic diffusivity, which is a more effective parameter than permeability for identify the complexity of flow pathways between measurement locations. Periodic tests were also conducted at multiple frequencies which provides a range in the radius of hydraulic penetration away from the oscillating well. By varying the radius of penetration, we attempt to interrogate the structure of the fracture network. Periodic tests, therefore, may be uniquely suited for verifying and/or calibrating DFN models.

  9. Size Effects on Deformation and Fracture of Scandium Deuteride Films.

    Energy Technology Data Exchange (ETDEWEB)

    Teresi, C. S. [Univ. of Minnesota, Minneapolis, MN (United States); Hintsala, E. [Univ. of Minnesota, Minneapolis, MN (United States); Hysitron, Inc., Eden Prairie, MN (United States); Adams, David P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Yang, Nancy Y. C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kammler, Daniel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Moody, N. R. [Univ. of Minnesota, Minneapolis, MN (United States); Gerberich, W. W. [Univ. of Minnesota, Minneapolis, MN (United States)

    2017-07-01

    Metal hydride films have been observed to crack during production and use, prompting mechanical property studies of scandium deuteride films. The following focuses on elastic modulus, fracture, and size effects observed in the system for future film mechanical behavior modeling efforts. Scandium deuteride films were produced through the deuterium charging of electron beam evaporated scandium films using X-ray diffraction, scanning Auger microscopy, and electron backscatter diffraction to monitor changes in the films before and after charging. Scanning electron microscopy, nanoindentation, and focused ion beam machined micropillar compression tests were used for mechanical characterization of the scandium deuteride films. The micropillars showed a size effect for flow stress, indicating that film thickness is a relevant tuning parameter for film performance, and that fracture was controlled by the presence of grain boundaries. Elastic modulus was determined by both micropillar compression and nanoindentation to be approximately 150 GPa, Fracture studies of bulk film channel cracking as well as compression induced cracks in some of the pillars yielded a fracture toughness around 1.0 MPa-m1/2. Preliminary Weibull distributions of fracture in the micropillars are provided. Despite this relatively low value of fracture toughness, scandium deuteride micropillars can undergo a large degree of plasticity in small volumes and can harden to some degree, demonstrating the ductile and brittle nature of this material

  10. Forearm diaphyseal fractures in the adolescent population: treatment and management.

    Science.gov (United States)

    Truntzer, Jeremy; Vopat, Matthew L; Kane, Patrick M; Christino, Melissa A; Katarincic, Julia; Vopat, Bryan G

    2015-02-01

    Pediatric both-bone diaphyseal forearm fractures are commonly treated in a variety of clinical settings. Most often, closed reduction followed by immobilization leads to satisfactory results. However, in the adolescent population (10-16 years of age), forearm fractures are more challenging due to less remodeling potential. The purpose of this review was to provide an overview of the anatomy, biomechanics, and treatment options relevant to adolescent patients. A systematic review of peer-reviewed publications and abstracts related to the treatment for pediatric both-bone diaphyseal forearm fractures in adolescents was carried out. Forearm fractures in the pediatric population are most common following indirect blows to the forearm. When treating these fractures using closed reduction, it is important to recognize the muscular attachments of the forearm. In roughly 70-90% of cases, closed reduction leads to adequate alignment. In all cases, return to function is the primary goal; however, exact alignment parameters remain controversial. In the adolescent population, surgical treatment has risen substantially in the last few decades. Intramedullary nailing and open reduction using plate fixation are the two most common operative techniques. Unfortunately, recent results have shown that nonunion, malunion, and overall complication rates are higher in older pediatric patients. Moreover, no consensus exists regarding one technique over another. Both-bone diaphyseal fractures in the adolescent population present unique challenges regarding optimal treatment, especially when considering surgical intervention. Further research is necessary to better understand indications for specific surgical treatment.

  11. 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.

  12. Energy based methods for determining elastic plastic fracture

    International Nuclear Information System (INIS)

    Witt, F.J.

    1979-01-01

    Several methods are currently in use or under study for calculating various conditions of fracturing for varying degrees of plasticity. Among these are innovations on the J-integral concept, crack opening displacement or angle, the two parameter concept and the equivalent energy method. Methods involving crack arrest and ductile tearing also fall in this category. Each of these methods have many salient points and some efforts are underway to establish the underlying relationship between them. In this paper, the current research directions of J-integral and equivalent energy methodologies are reviewed with a broader discussion presented for the equivalent energy methodology. The fundamental basis of equivalent energy methodology rests with the volumetric energy ratio. For fractures governed by linear elastic fracture mechanics, the volumetric energy ratio is independent of flaw size and geometry and depends only on the scale factor between model and prototype and temperature. The behavioral aspects of the volumetric energy ratios have been investigated throughout the temperature range from brittle fracture to fully ductile fracture. For five different specimen and structural configurations it has been shown experimentally that the volumetric energy ratio retains its basic properties. That is, the volumetric energy ratio while changing in actual value, maintains its independence of geometry and flaw size while retaining a unique dependence on scale factor and temperature. This property interpreted in terms of fracture mechanics leads to the equivalent energy method. (orig.)

  13. Migration of Water Pulse Through Fractured Porous Media

    International Nuclear Information System (INIS)

    Finsterle, S.; Fabryka-Martin, J. T.; Wang, J. S. Y.

    2001-01-01

    Contaminant transport from waste-disposal sites is strongly affected by the presence of fractures and the degree of fracture-matrix interaction. Characterization of potential contaminant plumes at such sites is difficult, both experimentally and numerically. Simulations of water flow through fractured rock were performed to examine the penetration depth of a large pulse of water entering such a system. Construction water traced with lithium bromide was released during the excavation of a tunnel at Yucca Mountain, Nevada, which is located in an unsaturated fractured tuff formation. Modeling of construction-water migration is qualitatively compared with bromide-to-chloride (Br/CI) ratio data for pore-water salts extracted from drillcores. The influences of local heterogeneities in the fracture network and variations in hydrogeologic parameters were examined by sensitivity analyses and Monte Carlo simulations. The simulation results are qualitatively consistent with the observed Br/CI signals, although these data may only indicate a minimum penetration depth, and water may have migrated further through the fracture network

  14. Fracture mechanics evaluation of heavy welded structures

    International Nuclear Information System (INIS)

    Sprung, I.; Ericksson, C.W.; Zilberstein, V.A.

    1982-01-01

    This paper describes some applications of nondestructive examination (NDE) and engineering fracture mechanics to evaluation of flaws in heavy welded structures. The paper discusses not only widely recognized linear elastic fracture mechanics (LEFM) analysis, but also methods of the elastic-plastic fracture mechanics (EPFM), such as COD, J-integral, and Failure Assessment Diagram. Examples are given to highlight the importance of interaction between specialists providing input and the specialists performing the analysis. The paper points out that the critical parameters for as-welded structures when calculated by these methods are conservative since they are based on two pessimistic assumptions: that the magnitude of residual stress is always at the yield strength level, and that the residual stress always acts in the same direction as the applied (mechanical) stress. The suggestion is made that it would be prudent to use the COD or the FAD design curves for a conservative design. The appendix examines a J-design curve modified to include residual stresses

  15. Theoretical and laboratory investigations of flow through fractures in crystalline rock

    International Nuclear Information System (INIS)

    Witherspoon, P.A.; Watkins, D.J.; Tsang, Y.W.

    1981-01-01

    A theoretical model developed for flow through a deformable fracture subject to stresses was successfully tested against laboratory experiments. The model contains no arbitrary parameters and can be used to predict flow rates through a single fracture if the fractional fracture contact area can be estimated and if stress-deformation data are available. These data can be obtained from laboratory or in situ tests. The model has considerable potential for practical application. The permeability of ultralarge samples of fractured crystalline rock as a function of stresses was measured. Results from tests on a pervasively fractured 1-m-diameter specimen of granitic rock showed that drastically simplifying assumptions must be used to apply theoretical models to this type of rock mass. Simple models successfully reproduce the trend of reduced permeability as stress is applied in a direction normal to the fracture plane. The tests also demonstrated how fracture conductivity increases as a result of dilatancy associated with shear displacements. The effect of specimen size on the hydraulic properties of fractured rock was also investigated. Permeability tests were performed on specimens of charcoal black granite containing a single fracture subjected to normal stress. Results are presented for tests performed on a 0.914-m-diameter specimen and on the same specimen after it had been reduced to 0.764 m in diameter. The data show that fracture conductivity is sensitive to stress history and sample disturbance

  16. Can we assess healing of surgically treated long bone fractures on radiograph?

    Science.gov (United States)

    Perlepe, V; Omoumi, P; Larbi, A; Putineanu, D; Dubuc, J-E; Schubert, T; Vande Berg, B

    2018-06-01

    To determine the frequency and causes for limitations in the radiographic evaluation of surgically treated long bone fractures. Six readers separately scored 140 sets of antero-posterior (AP) and lateral radiographs of surgically treated long bone fractures, using a radiographic union score (RUS). We determined the rate of assessability of the fracture edges at each of the four cortical segments (n=560) seen tangentially on the two radiographs and the causes for non-assessability. The rate of feasibility of the RUS (more than two fracture edges assessable per fracture) was determined and compared according to different parameters. Fracture edges were visible in 71% to 81% of the 560 cortical segments. Metal hardware superimposition was the most frequent cause for non-assessability (79-95%). RUS values could be calculated in 58% to 75% of fractures. Scoring was statistically significantly less frequently calculable in plated (31-56%) than in nailed fractures (90-97%), in distal (47-61%) than in proximal (78-89%) bones and in upper (27-49%) than in lower (76-91%) limb bones (P≤0.01). The type of stabilization hardware is the main limiting factor in the radiographic assessment of surgically treated long bone fractures. Scoring was feasible in only 31% to 56% of plated fractures. Copyright © 2018 Société française de radiologie. Published by Elsevier Masson SAS. All rights reserved.

  17. Inclusion of Topological Measurements into Analytic Estimates of Effective Permeability in Fractured Media

    Science.gov (United States)

    Sævik, P. N.; Nixon, C. W.

    2017-11-01

    We demonstrate how topology-based measures of connectivity can be used to improve analytical estimates of effective permeability in 2-D fracture networks, which is one of the key parameters necessary for fluid flow simulations at the reservoir scale. Existing methods in this field usually compute fracture connectivity using the average fracture length. This approach is valid for ideally shaped, randomly distributed fractures, but is not immediately applicable to natural fracture networks. In particular, natural networks tend to be more connected than randomly positioned fractures of comparable lengths, since natural fractures often terminate in each other. The proposed topological connectivity measure is based on the number of intersections and fracture terminations per sampling area, which for statistically stationary networks can be obtained directly from limited outcrop exposures. To evaluate the method, numerical permeability upscaling was performed on a large number of synthetic and natural fracture networks, with varying topology and geometry. The proposed method was seen to provide much more reliable permeability estimates than the length-based approach, across a wide range of fracture patterns. We summarize our results in a single, explicit formula for the effective permeability.

  18. Characterizing hydraulic fractures in shale gas reservoirs using transient pressure tests

    Directory of Open Access Journals (Sweden)

    Cong Wang

    2015-06-01

    This work presents an unconventional gas reservoir simulator and its application to quantify hydraulic fractures in shale gas reservoirs using transient pressure data. The numerical model incorporates most known physical processes for gas production from unconventional reservoirs, including two-phase flow of liquid and gas, Klinkenberg effect, non-Darcy flow, and nonlinear adsorption. In addition, the model is able to handle various types and scales of fractures or heterogeneity using continuum, discrete or hybrid modeling approaches under different well production conditions of varying rate or pressure. Our modeling studies indicate that the most sensitive parameter of hydraulic fractures to early transient gas flow through extremely low permeability rock is actually the fracture-matrix contacting area, generated by fracturing stimulation. Based on this observation, it is possible to use transient pressure testing data to estimate the area of fractures generated from fracturing operations. We will conduct a series of modeling studies and present a methodology using typical transient pressure responses, simulated by the numerical model, to estimate fracture areas created or to quantity hydraulic fractures with traditional well testing technology. The type curves of pressure transients from this study can be used to quantify hydraulic fractures in field application.

  19. Pore-fluid effects on seismic waves in vertically fractured earth with orthotropic symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Berryman, J.G.

    2010-05-15

    For elastically noninteracting vertical-fracture sets at arbitrary orientation angles to each other, a detailed model is presented in which the resulting anisotropic fractured medium generally has orthorhombic symmetry overall. Some of the analysis methods and ideas of Schoenberg are emphasized, together with their connections to other similarly motivated and conceptually related methods by Sayers and Kachanov, among others. Examples show how parallel vertical-fracture sets having HTI (horizontal transversely isotropic) symmetry transform into orthotropic fractured media if some subsets of the vertical fractures are misaligned with the others, and then the fractured system can have VTI (vertical transversely isotropic) symmetry if all of the fractures are aligned randomly or half parallel and half perpendicular to a given vertical plane. An orthotropic example having vertical fractures in an otherwise VTI earth system (studied previously by Schoenberg and Helbig) is compared with the other examples treated and it is finally shown how fluids in the fractures affect the orthotropic poroelastic system response to seismic waves. The key result is that fracture-influence parameters are multiplied by a factor of (1-B), where 0 {le} B < 1 is Skempton's second coefficient for poroelastic media. Skempton's B coefficient is itself a measurable characteristic of fluid-saturated porous rocks, depending on porosity, solid moduli, and the pore-fluid bulk modulus. For heterogeneous porous media, connections between the present work and earlier related results of Brown and Korringa are also established.

  20. Simulation of water flow in fractured porous medium by using discretized virtual internal bond

    Science.gov (United States)

    Peng, Shujun; Zhang, Zhennan; Li, Chunfang; He, Guofu; Miao, Guoqing

    2017-12-01

    The discretized virtual internal bond (DVIB) is adopted to simulate the water flow in fractured porous medium. The intact porous medium is permeable because it contains numerous micro cracks and pores. These micro discontinuities construct a fluid channel network. The representative volume of this fluid channel network is modeled as a lattice bond cell with finite number of bonds in statistical sense. Each bond serves as a fluid channel. In fractured porous medium, many bond cells are cut by macro fractures. The conductivity of the fracture facet in a bond cell is taken over by the bonds parallel to the flow direction. The equivalent permeability and volumetric storage coefficient of a micro bond are calibrated based on the ideal bond cell conception, which makes it unnecessary to consider the detailed geometry of a specific element. Such parameter calibration method is flexible and applicable to any type of element. The accuracy check results suggest this method has a satisfying accuracy in both the steady and transient flow simulation. To simulate the massive fractures in rockmass, the bond cells intersected by fracture are assigned aperture values, which are assumed random numbers following a certain distribution law. By this method, any number of fractures can be implicitly incorporated into the background mesh, avoiding the setup of fracture element and mesh modification. The fracture aperture heterogeneity is well represented by this means. The simulation examples suggest that the present method is a feasible, simple and efficient approach to the numerical simulation of water flow in fractured porous medium.

  1. Staged fracturing of horizontal shale gas wells with temporary plugging by sand filling

    Directory of Open Access Journals (Sweden)

    Xing Liang

    2017-03-01

    Full Text Available Due to downhole complexities, shale-gas horizontal well fracturing in the Sichuan Basin suffered from casing deformation and failure to apply the technique of cable-conveyed perforation bridge plug. In view of these problems, a new technique of staged volume fracturing with temporary plugging by sand filling is employed. Based on theoretical analyses and field tests, a design of optimized parameters of coiled tubing-conveyed multi-cluster sand-blasting perforation and temporary plugging by sand filling was proposed. It was applied in the horizontal Well ZJ-1 in which casing deformation occurred. The following results are achieved in field operations. First, this technique enables selective staged fracturing in horizontal sections. Second, this technique can realize massive staged fracturing credibly without mechanical plugging, with the operating efficiency equivalent to the conventional bridge plug staged fracturing. Third, full-hole is preserved after fracturing, thus it is possible to directly conduct an open flow test without time consumption of a wiper trip. The staged volume fracturing with temporary plugging by sand filling facilitated the 14-stage fracturing in Well ZJ-1, with similar SRV to that achieved by conventional bridge plug staged fracturing and higher gas yield than neighboring wells on the same well pad. Thus, a new and effective technique is presented in multi-cluster staged volume fracturing of shale gas horizontal wells.

  2. Numerical modelling of fracture displacements due to thermal load from a KBS-3 repository

    Energy Technology Data Exchange (ETDEWEB)

    Hakami, Eva; Olofsson, Stig-Olof [Itasca Geomekanik AB, Stockholm (Sweden)

    2002-01-01

    The objective of the project has been to estimate the largest shear displacements that could be expected on a pre-existing fracture located in the repository area, due to the heat release from the deposited waste. Two-dimensional numerical analyses using the 'Universal Distinct Element Code' (UDEC) have been performed. The UDEC models represent a vertical cross section of a KBS-3 type repository with a large planar fracture intersecting a deposition hole at the repository centre. The extension, dip and mechanical properties of the fracture were changed in different models to evaluate the influence of these parameters on fracture shear displacements. The fracture was modelled using a Coulomb slip criterion with no cohesion and no dilation. The rock mass surrounding the fracture was modelled as a homogeneous, isotropic and elastic material, with a Young's modulus of 40 GPa. The initial heat release per unit repository area was assumed to be 8W/m{sup 2} (total power/total repository area). The shear displacements occur due to the thermal expansion of the rock surrounding the heat generating canisters. The rock mass is almost free to expand vertically, but is constrained horizontally, which gives a temperature-induced addition of shear stresses in the plane of the fracture. The shear movement of the fracture therefore follows the temperature development in the surrounding rock and the maximum shear displacement develops about 200 years after the waste deposition. Altogether, twenty cases are analysed. The maximum shear displacement, which occurs at the fracture centre, amounts to 0.2-13.8 cm depending on the fracture parameters. Among the analysed cases, the largest shear values, about 13 cm, was calculated for the cases with about 700 m long fractures with a shear stiffness of 0.005 GPa/m. Also, for large fractures with a higher shear stiffness of 5 GPa/m, but with a low friction angle (15 deg), the shear displacement reaches similar magnitudes, about

  3. Fatigue and fracture: Overview

    Science.gov (United States)

    Halford, G. R.

    1984-01-01

    A brief overview of the status of the fatigue and fracture programs is given. The programs involve the development of appropriate analytic material behavior models for cyclic stress-strain-temperature-time/cyclic crack initiation, and cyclic crack propagation. The underlying thrust of these programs is the development and verification of workable engineering methods for the calculation, in advance of service, of the local cyclic stress-strain response at the critical life governing location in hot section compounds, and the resultant crack initiation and crack growth lifetimes.

  4. Femoral shaft fractures

    International Nuclear Information System (INIS)

    Bender, C.E.; Campbell, D.C. II

    1985-01-01

    The femur is the longest, largest, and strongest bone in the body. Because of its length, width, and role as primary weight-bearing bone, it must tolerate the extremes of axial loading and angulatory stresses. Massive musculature envelopes the femur. This masculature provides abundant blood supply to the bone, which also allows great potential for healing. Thus, the most significant problem relating to femoral shaft fractures is not healing, but restoration of bone length and alignment so that the femoral shaft will tolerate the functional stresses demanded of it

  5. Fracturing of subterranean formations

    Energy Technology Data Exchange (ETDEWEB)

    Kiel, O.M.; Kidwell, A.L.

    1968-03-19

    This method of propping fractured formations results in high conductivities. In the method, certain naturally occurring crystals are used as propping agents. Suitable crystals include garnet, corundum, zircon, rutile, high-temperature quartz, and other minerals which have Moh's hardness values of about 6 or greater and weather out as individual crystals of about 40 mesh or larger. These are said to result in permeabilities significantly higher than those obtained with ordinary quartz sand, metallic shot, glass beads, plastic particles, walnut hulls, or similar materials. (10 claims)

  6. Characterisation of hydraulically-active fractures in a fractured ...

    African Journals Online (AJOL)

    ... in the initial stage of a site investigation to select the optimal site location or to evaluate the hydrogeological properties of fractures in underground exploration studies, such as those related geothermal reservoir evaluation and radioactive waste disposal. Keywords: self-potential method, hydraulically-conductive fractures, ...

  7. Ankle fractures have features of an osteoporotic fracture.

    Science.gov (United States)

    Lee, K M; Chung, C Y; Kwon, S S; Won, S H; Lee, S Y; Chung, M K; Park, M S

    2013-11-01

    We report the bone attenuation of ankle joint measured on computed tomography (CT) and the cause of injury in patients with ankle fractures. The results showed age- and gender-dependent low bone attenuation and low-energy trauma in elderly females, which suggest the osteoporotic features of ankle fractures. This study was performed to investigate the osteoporotic features of ankle fracture in terms of bone attenuation and cause of injury. One hundred ninety-four patients (mean age 51.0 years, standard deviation 15.8 years; 98 males and 96 females) with ankle fracture were included. All patients underwent CT examination, and causes of injury (high/low-energy trauma) were recorded. Mean bone attenuations of the talus, medial malleolus, lateral malleolus, and distal tibial metaphysis were measured on CT images. Patients were divided into younger age (fractures than the younger age group. With increasing age, bone attenuations tended to decrease and the difference of bone attenuation between the genders tended to increase in the talus, medial malleolus, lateral malleolus, and distal tibial metaphysis. Ankle fracture had features of osteoporotic fracture that is characterized by age- and gender-dependent low bone attenuation. Ankle fracture should not be excluded from the clinical and research interest as well as from the benefit of osteoporosis management.

  8. Basic principles of fracture treatment in children.

    Science.gov (United States)

    Ömeroğlu, Hakan

    2018-04-01

    This review aims to summarize the basic treatment principles of fractures according to their types and general management principles of special conditions including physeal fractures, multiple fractures, open fractures, and pathologic fractures in children. Definition of the fracture is needed for better understanding the injury mechanism, planning a proper treatment strategy, and estimating the prognosis. As the healing process is less complicated, remodeling capacity is higher and non-union is rare, the fractures in children are commonly treated by non-surgical methods. Surgical treatment is preferred in children with multiple injuries, in open fractures, in some pathologic fractures, in fractures with coexisting vascular injuries, in fractures which have a history of failed initial conservative treatment and in fractures in which the conservative treatment has no/little value such as femur neck fractures, some physeal fractures, displaced extension and flexion type humerus supracondylar fractures, displaced humerus lateral condyle fractures, femur, tibia and forearm shaft fractures in older children and adolescents and unstable pelvis and acetabulum fractures. Most of the fractures in children can successfully be treated by non-surgical methods.

  9. Risk Assessment of Bone Fracture During Space Exploration Missions to the Moon and Mars

    Science.gov (United States)

    Lewandowski, Beth E.; Myers, Jerry G.; Nelson, Emily S.; Griffin, Devon

    2008-01-01

    The possibility of a traumatic bone fracture in space is a concern due to the observed decrease in astronaut bone mineral density (BMD) during spaceflight and because of the physical demands of the mission. The Bone Fracture Risk Module (BFxRM) was developed to quantify the probability of fracture at the femoral neck and lumbar spine during space exploration missions. The BFxRM is scenario-based, providing predictions for specific activities or events during a particular space mission. The key elements of the BFxRM are the mission parameters, the biomechanical loading models, the bone loss and fracture models and the incidence rate of the activity or event. Uncertainties in the model parameters arise due to variations within the population and unknowns associated with the effects of the space environment. Consequently, parameter distributions were used in Monte Carlo simulations to obtain an estimate of fracture probability under real mission scenarios. The model predicts an increase in the probability of fracture as the mission length increases and fracture is more likely in the higher gravitational field of Mars than on the moon. The resulting probability predictions and sensitivity analyses of the BFxRM can be used as an engineering tool for mission operation and resource planning in order to mitigate the risk of bone fracture in space.

  10. Residual lifetime and 10 year absolute risks of osteoporotic fractures in Chinese men and women.

    Science.gov (United States)

    Si, Lei; Winzenberg, Tania M; Chen, Mingsheng; Jiang, Qicheng; Palmer, Andrew J

    2015-06-01

    To determine the residual lifetime and 10 year absolute risks of osteoporotic fractures in Chinese men and women. A validated state-transition microsimulation model was used. Microsimulation and probabilistic sensitivity analyses were performed to address the uncertainties in the model. All parameters including fracture incidence rates and mortality rates were retrieved from published literature. Simulated subjects were run through the model until they died to estimate the residual lifetime fracture risks. A 10 year time horizon was used to determine the 10 year fracture risks. We estimated the risk of only the first osteoporotic fracture during the simulation time horizon. The residual lifetime and 10 year risks of having the first osteoporotic (hip, clinical vertebral or wrist) fracture for Chinese women aged 50 years were 40.9% (95% CI: 38.3-44.0%) and 8.2% (95% CI: 6.8-9.3%) respectively. For men, the residual lifetime and 10 year fracture risks were 8.7% (95% CI: 7.5-9.8%) and 1.2% (95% CI: 0.8-1.7%) respectively. The residual lifetime fracture risks declined with age, whilst the 10 year fracture risks increased with age until the short-term mortality risks outstripped the fracture risks. Residual lifetime and 10 year clinical vertebral fracture risks were higher than those of hip and wrist fractures in both sexes. More than one third of the Chinese women and approximately one tenth of the Chinese men aged 50 years are expected to sustain a major osteoporotic fracture in their remaining lifetimes. Due to increased fracture risks and a rapidly ageing population, osteoporosis will present a great challenge to the Chinese healthcare system. While national data was used wherever possible, regional Chinese hip and clinical vertebral fracture incidence rates were used, wrist fracture rates were taken from a Norwegian study and calibrated to the Chinese population. Other fracture sites like tibia, humerus, ribs and pelvis were not included in the analysis, thus these

  11. Mandibular ramus fractures: a rarity.

    Science.gov (United States)

    Kale, Tejraj Pundalik; Kotrashetti, S M; Louis, Archana; Lingaraj, J B; Sarvesh, B U

    2013-01-01

    To determine the incidence of mandibular ramus fractures in KLE's PK Hospital and to analyze the outcome of open reduction and internal fixation of these fractures. Using a retrospective study design, records of all trauma patients who reported to the Department of Oral and Maxillofacial Surgery, KLE's PK Hospital Belgaum, between the years January 2006 to October 2011 was obtained from the medical records office. The data variables that were analyzed were the name, age, sex, cause of injury, pretreatment occlusion, treatment given, period of MMF and post-treatment occlusion. Total number of mandibular fracture cases was 298. Ramus fractures were 10 in number which accounted for 3.3% of fractures. The age range of these 10 patients was seen to be between 20 to 80 years with the average age being 35.6 years. Of these 10 patients, 9 were male and 1 was female and 7 patients were treated by open reduction and internal fixation and the remaining 3 by closed reduction. The average period of MMF was 3 days for the patients who underwent open reduction and internal fixation. There was improvement in occlusion in all 10 patients post-treatment and there was no complication reported in any of the cases. Ramus fractures accounted for 3.3% of all mandibular fractures. Open reduction and internal fixation of ramus fractures ensures adequate functional and anatomic reduction. This study makes an attempt to throw a light on the increasing incidence of ramus fractures and a successful management of these fractures by open reduction and internal fixation. How to cite this article: Kale TP, Kotrashetti SM, Louis A, Lingaraj JB, Sarvesh BU. Mandibular Ramus Fractures: A Rarity. J Contemp Dent Pract 2013;14(1):39-42. Source of support: Nil Conflict of interest: None declared.

  12. Modeling interfacial fracture in Sierra.

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Arthur A.; Ohashi, Yuki; Lu, Wei-Yang; Nelson, Stacy A. C.; Foulk, James W.,; Reedy, Earl David,; Austin, Kevin N.; Margolis, Stephen B.

    2013-09-01

    This report summarizes computational efforts to model interfacial fracture using cohesive zone models in the SIERRA/SolidMechanics (SIERRA/SM) finite element code. Cohesive surface elements were used to model crack initiation and propagation along predefined paths. Mesh convergence was observed with SIERRA/SM for numerous geometries. As the funding for this project came from the Advanced Simulation and Computing Verification and Validation (ASC V&V) focus area, considerable effort was spent performing verification and validation. Code verification was performed to compare code predictions to analytical solutions for simple three-element simulations as well as a higher-fidelity simulation of a double-cantilever beam. Parameter identification was conducted with Dakota using experimental results on asymmetric double-cantilever beam (ADCB) and end-notched-flexure (ENF) experiments conducted under Campaign-6 funding. Discretization convergence studies were also performed with respect to mesh size and time step and an optimization study was completed for mode II delamination using the ENF geometry. Throughout this verification process, numerous SIERRA/SM bugs were found and reported, all of which have been fixed, leading to over a 10-fold increase in convergence rates. Finally, mixed-mode flexure experiments were performed for validation. One of the unexplained issues encountered was material property variability for ostensibly the same composite material. Since the variability is not fully understood, it is difficult to accurately assess uncertainty when performing predictions.

  13. GUNSHOT FRACTURES OF TIBIA AND FEMUR - EXCELLENT ...

    African Journals Online (AJOL)

    2011-10-10

    Oct 10, 2011 ... fractures due to gunshot injury grafted with reamed bone marrow and immobilised with Surgical ... open fractures, which pose a challenging problem .... Table 2. Gustillo-Anderson Classification of fractures and infection.

  14. Image diagnosis of nasal bone fracture

    International Nuclear Information System (INIS)

    Hirota, Yoshiharu; Shimizu, Yayoi; Iinuma, Toshitaka.

    1988-01-01

    Twenty cases of nasal bone fractures were evaluated as to the types of fractures based upon HRCT findings. Conventional X-Ray films for nasal bones were analyzed and compared with HRCT findings. Nasal bone fractures were classified into lateral and frontal fractures. HRCT images were evaluated in three planes including upper, middle and lower portions of the nasal bone. Fractures favored males of teens. Lateral fracture gave rise to the fractures of the nasal bone opposite to the external force, loosening of the ipsilateral nasomaxillary sutures and fractures of the frontal process of the maxilla. Conventional X-Ray films were reevaluated after HRCT evaluation and indications of nasal bone fractures were determined. In addition to the discontinuity of the nasal dorsum, fracture lines parallel to and beneath the nasal dorsum and indistinct fracture lines along the nasomaxillary sutures are the indication of nasal bone fractures by conventional X-Ray films. (author)

  15. Associations of early premenopausal fractures with subsequent fractures vary by sites and mechanisms of fractures.

    Science.gov (United States)

    Honkanen, R; Tuppurainen, M; Kroger, H; Alhava, E; Puntila, E

    1997-04-01

    In a retrospective population-based study we assessed whether and how self-reported former fractures sustained at the ages of 20-34 are associated with subsequent fractures sustained at the ages of 35-57. The 12,162 women who responded to fracture questions of the baseline postal enquiry (in 1989) of the Kuopio Osteoporosis Study, Finland formed the study population. They reported 589 former and 2092 subsequent fractures. The hazard ratio (HR), with 95% confidence interval (CI), of a subsequent fracture was 1.9 (1.6-2.3) in women with the history of a former fracture compared with women without such a history. A former low-energy wrist fracture was related to subsequent low-energy wrist [HR = 3.7 (2.0-6.8)] and high-energy nonwrist [HR = 2.4 (1.3-4.4)] fractures, whereas former high-energy nonwrist fractures were related only to subsequent high-energy nonwrist [HR = 2.8 (1.9-4.1)] but not to low-energy wrist [HR = 0.7 (0.3-1.8)] fractures. The analysis of bone mineral density (BMD) data of a subsample of premenopausal women who underwent dual x-ray absorptiometry (DXA) during 1989-91 revealed that those with a wrist fracture due to a fall on the same level at the age of 20-34 recorded 6.5% lower spinal (P = 0.140) and 10.5% lower femoral (P = 0.026) BMD than nonfractured women, whereas the corresponding differences for women with a former nonwrist fracture due to high-energy trauma were -1.8% (P = 0.721) and -2.4% (P = 0. 616), respectively. Our results suggest that an early premenopausal, low-energy wrist fracture is an indicator of low peak BMD which predisposes to subsequent fractures in general, whereas early high-energy fractures are mainly indicators of other and more specific extraskeletal factors which mainly predispose to same types of subsequent fractures only.

  16. Fracture dynamics of a propagating crack in a pressurized ductile cylinder

    International Nuclear Information System (INIS)

    Emery, A.F.; Love, W.J.; Kobayashi, A.S.

    1977-01-01

    A suddenly-introduced axial through-crack in the wall of a pipe pressurized by hot water is allowed to propagate according to Weiss' notch-strength theory of ductile static fracture. For this somewhat ductile material of A533B steel, Weiss' criterion was extended of dynamic fracture without modification. This dynamic-fracture criterion enabled a unique comparison to be obtained for the results of ductile-fracture with those of brittle-fracture in a fracturing A533B steel pipe. Since the pipe cross-sectional area is likely to increase with large flap motions under ductile tearing, a large deformation-shell-finite-difference-dynamic-code which includes rotary inertia was used in this analysis. The uniaxial-stress-strain curve of A533B steel was approximated by a bilinear stress-strain where Von-Misses yield criterion and associated flow rule were used in the elastic-plastic analysis. The fluid pressure was assumed constant and thus pipe flaps are only lightly loaded by pressure in this analysis. In previous publications, the authors have compared their preliminary results for the shell motion obtained through their model for a fracturing pipe with those of Kanninen, et al., and Freund, et al., to evaluate the effects of pressure loading on the crack flaps and the differences between small and large deflection results. In this paper, the differences in crack-propagation behavior of a fracturing pipe composed of the same A533B but subjected to a brittle or a ductile-fracture criterion are discussed. An important conclusion in fracture dynamics derived from analyses is that a smoothly-varying crack velocity will require a non-unique crack-velocity-versus-dynamic-fracture-parameter-relation while a unique and smoothly-varying crack-velocity-versus-dynamic-fracture-parameter-relation will demand an intermittently-propagating crack

  17. Mechanical transport in two-dimensional networks of fractures

    International Nuclear Information System (INIS)

    Endo, H.K.

    1984-04-01

    The objectives of this research are to evaluate directional mechanical transport parameters for anisotropic fracture systems, and to determine if fracture systems behave like equivalent porous media. The tracer experiments used to measure directional tortuosity, longitudinal geometric dispersivity, and hydraulic effective porosity are conducted with a uniform flow field and measurements are made from the fluid flowing within a test section where linear length of travel is constant. Since fluid flow and mechanical transport are coupled processes, the directional variations of specific discharge and hydraulic effective porosity are measured in regions with constant hydraulic gradients to evaluate porous medium equivalence for the two processes, respectively. If the fracture region behaves like an equivalent porous medium, the system has the following stable properties: (1) specific discharge is uniform in any direction and can be predicted from a permeability tensor; and (2) hydraulic effective porosity is directionally stable. Fracture systems with two parallel sets of continuous fractures satisfy criterion 1. However, in these systems hydraulic effective porosity is directionally dependent, and thus, criterion 2 is violated. Thus, for some fracture systems, fluid flow can be predicted using porous media assumptions, but it may not be possible to predict transport using porous media assumptions. Two discontinuous fracture systems were studied which satisfied both criteria. Hydraulic effective porosity for both systems has a value between rock effective porosity and total porosity. A length-density analysis (LDS) of Canadian fracture data shows that porous media equivalence for fluid flow and transport is likely when systems have narrow aperture distributions. 54 references, 90 figures, 7 tables

  18. External fixation of tibial pilon fractures and fracture healing.

    Science.gov (United States)

    Ristiniemi, Jukka

    2007-06-01

    Distal tibial fractures are rare and difficult to treat because the bones are subcutaneous. External fixation is commonly used, but the method often results in delayed union. The aim of the present study was to find out the factors that affect fracture union in tibial pilon fractures. For this purpose, prospective data collection of tibial pilon fractures was carried out in 1998-2004, resulting in 159 fractures, of which 83 were treated with external fixation. Additionally, 23 open tibial fractures with significant > 3 cm bone defect that were treated with a staged method in 2000-2004 were retrospectively evaluated. The specific questions to be answered were: What are the risk factors for delayed union associated with two-ring hybrid external fixation? Does human recombinant BMP-7 accelerate healing? What is the role of temporary ankle-spanning external fixation? What is the healing potential of distal tibial bone loss treated with a staged method using antibiotic beads and subsequent autogenous cancellous grafting compared to other locations of the tibia? The following risk factors for delayed healing after external fixation were identified: post-reduction fracture gap of >3 mm and fixation of the associated fibula fracture. Fracture displacement could be better controlled with initial temporary external fixation than with early definitive fixation, but it had no significant effect on healing time, functional outcome or complication rate. Osteoinduction with rhBMP-7 was found to accelerate fracture healing and to shorten the sick leave. A staged method using antibiotic beads and subsequent autogenous cancellous grafting proved to be effective in the treatment of tibial bone loss. Healing potential of the bone loss in distal tibia was at least equally good as in other locations of the tibia.

  19. Rock fracture processes in chemically reactive environments

    Science.gov (United States)

    Eichhubl, P.

    2015-12-01

    Rock fracture is traditionally viewed as a brittle process involving damage nucleation and growth in a zone ahead of a larger fracture, resulting in fracture propagation once a threshold loading stress is exceeded. It is now increasingly recognized that coupled chemical-mechanical processes influence fracture growth in wide range of subsurface conditions that include igneous, metamorphic, and geothermal systems, and diagenetically reactive sedimentary systems with possible applications to hydrocarbon extraction and CO2 sequestration. Fracture processes aided or driven by chemical change can affect the onset of fracture, fracture shape and branching characteristics, and fracture network geometry, thus influencing mechanical strength and flow properties of rock systems. We are investigating two fundamental modes of chemical-mechanical interactions associated with fracture growth: 1. Fracture propagation may be aided by chemical dissolution or hydration reactions at the fracture tip allowing fracture propagation under subcritical stress loading conditions. We are evaluating effects of environmental conditions on critical (fracture toughness KIc) and subcritical (subcritical index) fracture properties using double torsion fracture mechanics tests on shale and sandstone. Depending on rock composition, the presence of reactive aqueous fluids can increase or decrease KIc and/or subcritical index. 2. Fracture may be concurrent with distributed dissolution-precipitation reactions in the hostrock beyond the immediate vicinity of the fracture tip. Reconstructing the fracture opening history recorded in crack-seal fracture cement of deeply buried sandstone we find that fracture length growth and fracture opening can be decoupled, with a phase of initial length growth followed by a phase of dominant fracture opening. This suggests that mechanical crack-tip failure processes, possibly aided by chemical crack-tip weakening, and distributed solution-precipitation creep in the

  20. Pediatric mandibular fractures.

    Science.gov (United States)

    Schweinfurth, J M; Koltai, P J

    1998-01-01

    Over the last 20 years, a revolution in the management of facial fractures has taken place. Refinements in biocompatible materials of great delicacy and strength along with advances in our understanding of biomechanics of the face, have rendered complex injuries consistently amenable to accurate 3-dimensional reconstruction. Furthermore, with the availability of education in the techniques of internal rigid fixation, these advanced techniques have become routine practice in adults. However, the suitability of rigid internal fixation for children remains controversial. There are many concerns about the effect of implanted hardware in the mandible of a growing child. In addition, some evidence suggests that the elevation of functional matrix off of bone may result in alterations in development. The goal is to restore the underlying bony architecture to its pre-injury position in a stable fashion, with a minimal of aesthetic and functional impairment. However, in children the treatment of bony injuries is most easily accomplished by techniques that may adversely effect craniofacial development. While it is not entirely possible to resolve this dilemma, there exists an extensive body of experimental and clinical information on the appropriate management of pediatric mandibular fractures which can be used to formulate a rational treatment plan for most cases. This paper presents an overview of the contemporary understanding and application of these treatment principles.

  1. Hydraulic fracturing proppants

    Directory of Open Access Journals (Sweden)

    V. P. P. de Campos

    Full Text Available Abstract Hydrocarbon reservoirs can be classified as unconventional or conventional depending on the oil and gas extraction difficulty, such as the need for high-cost technology and techniques. The hydrocarbon extraction from bituminous shale, commonly known as shale gas/oil, is performed by using the hydraulic fracturing technique in unconventional reservoirs where 95% water, 0.5% of additives and 4.5% of proppants are used. Environmental problems related to hydraulic fracturing technique and better performance/development of proppants are the current challenge faced by companies, researchers, regulatory agencies, environmentalists, governments and society. Shale gas is expected to increase USA fuel production, which triggers the development of new proppants and technologies of exploration. This paper presents a review of the definition of proppants, their types, characteristics and situation in the world market and information about manufacturers. The production of nanoscale materials such as anticorrosive and intelligent proppants besides proppants with carbon nanotubes is already carried out on a scale of tonnes per year in Belgium, Germany and Asia countries.

  2. Fracture induced electromagnetic radiation

    International Nuclear Information System (INIS)

    Frid, V; Rabinovitch, A; Bahat, D

    2003-01-01

    In our laboratory, we combine accurate electromagnetic radiation (EMR) measurements during fracture of rocks (carbonate and igneous) and transparent materials (glass, PMMA and glass ceramics) with careful fractographic methods. A critical analysis of experimental observations, accumulated here during the last decade together with supporting material from the works of other authors are used in this study to demonstrate the failure of all current models to explain the properties of EMR arising from fracture. The basic elements of a new model are proposed. These are (a) the EMR amplitude increases as long as the crack continues to grow, since new atomic bonds are severed and their contribution is added to the EMR. As a result, the atoms on both sides of the bonds are moved to 'non-equilibrium' positions relative to their steady state ones and begin to oscillate collectively in a manner similar to Debye model bulk oscillations - 'surface vibrational optical waves'; (b) when the crack halts, the waves and the EMR pulse amplitude decay by relaxation. These basic elements are already enough to describe the characteristics of the experimentally obtained isolated individual EMR pulses. These characteristics include the shape of the EMR pulse envelope, and the frequency, time duration and rise - fall time of the pulse

  3. Fracture induced electromagnetic radiation

    Energy Technology Data Exchange (ETDEWEB)

    Frid, V [Geological and Environmental Sciences Department, Deichmann Rock Mechanics Laboratory of the Negev, Ben Gurion University of the Negev, Beer Sheva (Israel); Rabinovitch, A [Physics Department, Deichmann Rock Mechanics Laboratory of the Negev, Ben Gurion University of the Negev, Beer Sheva (Israel); Bahat, D [Geological and Environmental Sciences Department, Deichmann Rock Mechanics Laboratory of the Negev, Ben Gurion University of the Negev, Beer Sheva (Israel)

    2003-07-07

    In our laboratory, we combine accurate electromagnetic radiation (EMR) measurements during fracture of rocks (carbonate and igneous) and transparent materials (glass, PMMA and glass ceramics) with careful fractographic methods. A critical analysis of experimental observations, accumulated here during the last decade together with supporting material from the works of other authors are used in this study to demonstrate the failure of all current models to explain the properties of EMR arising from fracture. The basic elements of a new model are proposed. These are (a) the EMR amplitude increases as long as the crack continues to grow, since new atomic bonds are severed and their contribution is added to the EMR. As a result, the atoms on both sides of the bonds are moved to 'non-equilibrium' positions relative to their steady state ones and begin to oscillate collectively in a manner similar to Debye model bulk oscillations - 'surface vibrational optical waves'; (b) when the crack halts, the waves and the EMR pulse amplitude decay by relaxation. These basic elements are already enough to describe the characteristics of the experimentally obtained isolated individual EMR pulses. These characteristics include the shape of the EMR pulse envelope, and the frequency, time duration and rise - fall time of the pulse.

  4. Osteoporosis, Fractures, and Diabetes

    Directory of Open Access Journals (Sweden)

    Peter Jackuliak

    2014-01-01

    Full Text Available It is well established that osteoporosis and diabetes are prevalent diseases with significant associated morbidity and mortality. Patients with diabetes mellitus have an increased risk of bone fractures. In type 1 diabetes, the risk is increased by ∼6 times and is due to low bone mass. Despite increased bone mineral density (BMD, in patients with type 2 diabetes the risk is increased (which is about twice the risk in the general population due to the inferior quality of bone. Bone fragility in type 2 diabetes, which is not reflected by bone mineral density, depends on bone quality deterioration rather than bone mass reduction. Thus, surrogate markers and examination methods are needed to replace the insensitivity of BMD in assessing fracture risks of T2DM patients. One of these methods can be trabecular bone score. The aim of the paper is to present the present state of scientific knowledge about the osteoporosis risk in diabetic patient. The review also discusses the possibility of problematic using the study conclusions in real clinical practice.

  5. Micromechanics based simulation of ductile fracture in structural steels

    Science.gov (United States)

    Yellavajjala, Ravi Kiran

    The broader aim of this research is to develop fundamental understanding of ductile fracture process in structural steels, propose robust computational models to quantify the associated damage, and provide numerical tools to simplify the implementation of these computational models into general finite element framework. Mechanical testing on different geometries of test specimens made of ASTM A992 steels is conducted to experimentally characterize the ductile fracture at different stress states under monotonic and ultra-low cycle fatigue (ULCF) loading. Scanning electron microscopy studies of the fractured surfaces is conducted to decipher the underlying microscopic damage mechanisms that cause fracture in ASTM A992 steels. Detailed micromechanical analyses for monotonic and cyclic loading are conducted to understand the influence of stress triaxiality and Lode parameter on the void growth phase of ductile fracture. Based on monotonic analyses, an uncoupled micromechanical void growth model is proposed to predict ductile fracture. This model is then incorporated in to finite element program as a weakly coupled model to simulate the loss of load carrying capacity in the post microvoid coalescence regime for high triaxialities. Based on the cyclic analyses, an uncoupled micromechanics based cyclic void growth model is developed to predict the ULCF life of ASTM A992 steels subjected to high stress triaxialities. Furthermore, a computational fracture locus for ASTM A992 steels is developed and incorporated in to finite element program as an uncoupled ductile fracture model. This model can be used to predict the ductile fracture initiation under monotonic loading in a wide range of triaxiality and Lode parameters. Finally, a coupled microvoid elongation and dilation based continuum damage model is proposed, implemented, calibrated and validated. This model is capable of simulating the local softening caused by the various phases of ductile fracture process under

  6. Cough-induced rib fractures.

    Science.gov (United States)

    Sano, Atsushi; Tashiro, Ken; Fukuda, Tsutomu

    2015-10-01

    Occasionally, patients who complain of chest pain after the onset of coughing are diagnosed with rib fractures. We investigated the characteristics of cough-induced rib fractures. Between April 2008 and December 2013, 17 patients were referred to our hospital with chest pain after the onset of coughing. Rib radiography was performed, focusing on the location of the chest pain. When the patient had other signs and symptoms such as fever or persistent cough, computed tomography of the chest was carried out. We analyzed the data retrospectively. Rib fractures were found in 14 of the 17 patients. The age of the patients ranged from 14 to 86 years (median 39.5 years). Ten patients were female and 4 were male. Three patients had chronic lung disease. There was a single rib fracture in 9 patients, and 5 had two or more fractures. The middle and lower ribs were the most commonly involved; the 10th rib was fractured most frequently. Cough-induced rib fractures occur in every age group regardless of the presence or absence of underlying disease. Since rib fractures often occur in the lower and middle ribs, rib radiography is useful for diagnosis. © The Author(s) 2015.

  7. Mechanical properties of fracture zones

    International Nuclear Information System (INIS)

    Leijon, B.

    1993-05-01

    Available data on mechanical characteristics of fracture zones are compiled and discussed. The aim is to improve the basis for adequate representation of fracture zones in geomechanical models. The sources of data researched are primarily borehole investigations and case studies in rock engineering, involving observations of fracture zones subjected to artificial load change. Boreholes only yield local information about the components of fracture zones, i.e. intact rock, fractures and various low-strength materials. Difficulties are therefore encountered in evaluating morphological and mechanical properties of fracture zones from borehole data. Although often thought of as macroscopically planar features, available field data consistently show that fracture zones are characterized by geometrical irregularities such as thickness variations, surface undulation and jogs. These irregularities prevail on all scales. As a result, fracture zones are on all scales characterized by large, in-plane variation of strength- and deformational properties. This has important mechanical consequences in terms of non-uniform stress transfer and complex mechanisms of shear deformation. Field evidence for these findings, in particular results from the underground research laboratory in Canada and from studies of induced fault slip in deep mines, is summarized and discussed. 79 refs

  8. Diplopia and Orbital Wall Fractures

    NARCIS (Netherlands)

    Boffano, P.; Roccia, F.; Gallesio, C.; Karagozoglu, K.H.; Forouzanfar, T.

    2014-01-01

    Diplopia is a symptom that is frequently associated with orbital wall fractures. The aim of this article was to present the incidence and patterns of diplopia after orbital wall blow-out fractures in 2 European centers, Turin and Amsterdam, and to identify any correlation between this symptom and

  9. Diplopia and orbital wall fractures

    NARCIS (Netherlands)

    Boffano, P.; Roccia, F.; Gallesio, C.; Karagozoglu, K.H.; Forouzanfar, T.

    2014-01-01

    Diplopia is a symptom that is frequently associated with orbital wall fractures. The aim of this article was to present the incidence and patterns of diplopia after orbital wall blow-out fractures in 2 European centers, Turin and Amsterdam, and to identify any correlation between this symptom and

  10. Mathematical modelling of fracture hydrology

    International Nuclear Information System (INIS)

    Herbert, A.W.; Hodgkinson, D.P.; Lever, D.A.; Robinson, P.C.; Rae, J.

    1985-06-01

    This report summarises the work performed between January 1983 and December 1984 for the CEC/DOE contract 'Mathematical Modelling of Fracture Hydrology', under the following headings: 1) Statistical fracture network modelling, 2) Continuum models of flow and transport, 3) Simplified models, 4) Analysis of laboratory experiments and 5) Analysis of field experiments. (author)

  11. Ankle Fractures: The Operative Outcome

    Directory of Open Access Journals (Sweden)

    Ahmad Hafiz Z

    2011-03-01

    Full Text Available Ankle fractures are commonly seen in orthopaedic practice. This retrospective study of patients with ankle fractures who underwent surgical treatment in our institution from January 2000 to December 2003 was undertaken to analyze the common causes and patterns of ankle fractures; and the functional outcome of operative treatment for these fractures. Eighty patients were identified and reviewed. There were 65 male (81.3% and 15 female patients (18.7% with age ranging from 13 to 71 years old (mean, 32.3y. Common causes of ankle fractures were trauma (especially motor vehicle accidents, sports injuries and the osteoporotic bones in the elderly. Weber C (64.0% was the most common pattern of fracture at presentation. The most common operative treatment for ankle fractures was open reduction and internal fixation (73 patients, 91.2%. Excellent and good outcomes were achieved in 93.8% of cases when measured using the Olerud and Molander scoring system for foot and ankle. In conclusion, operative treatment for ankle fractures restores sufficient stability and allowed mobility of the ankle joint.

  12. Isolated Transverse Sacrum Fracture: A Case Report

    Directory of Open Access Journals (Sweden)

    Cemil Kavalci

    2011-01-01

    Full Text Available Sacral fracture commonly results from high-energy trauma. Most insufficiency fractures of the sacrum are seen in women after the age of 70. Fractures of the sacrum are rare and generally combined with a concomitant pelvic fracture. Transverse sacral fractures are even less frequent which constitute only 3–5% of all sacral fractures. This type of fractures provide a diagnostic challenge. We report a unique case of isolated transverse fracture of sacrum in a young man sustained low-energy trauma. The patient presented to our emergency department after several hours of injury, and diagnosed by clinical features and roentgenogram findings.

  13. Fracture mechanisms and fracture control in composite structures

    Science.gov (United States)

    Kim, Wone-Chul

    Four basic failure modes--delamination, delamination buckling of composite sandwich panels, first-ply failure in cross-ply laminates, and compression failure--are analyzed using linear elastic fracture mechanics (LEFM) and the J-integral method. Structural failures, including those at the micromechanical level, are investigated with the aid of the models developed, and the critical strains for crack propagation for each mode are obtained. In the structural fracture analyses area, the fracture control schemes for delamination in a composite rib stiffener and delamination buckling in composite sandwich panels subjected to in-plane compression are determined. The critical fracture strains were predicted with the aid of LEFM for delamination and the J-integral method for delamination buckling. The use of toughened matrix systems has been recommended for improved damage tolerant design for delamination crack propagation. An experimental study was conducted to determine the onset of delamination buckling in composite sandwich panel containing flaws. The critical fracture loads computed using the proposed theoretical model and a numerical computational scheme closely followed the experimental measurements made on sandwich panel specimens of graphite/epoxy faceskins and aluminum honeycomb core with varying faceskin thicknesses and core sizes. Micromechanical models of fracture in composites are explored to predict transverse cracking of cross-ply laminates and compression fracture of unidirectional composites. A modified shear lag model which takes into account the important role of interlaminar shear zones between the 0 degree and 90 degree piles in cross-ply laminate is proposed and criteria for transverse cracking have been developed. For compressive failure of unidirectional composites, pre-existing defects play an important role. Using anisotropic elasticity, the stress state around a defect under a remotely applied compressive load is obtained. The experimentally

  14. Radiographic evaluation of maxillofacial fractures

    International Nuclear Information System (INIS)

    Litwan, M.; Fliegel, C.

    1986-01-01

    The course and configuration of typical maxillofacial fractures (type Le Fort I-III) and lateral maxillary fractures including the zygomatic arch were reconstructed in detail by application of barium paste on a bony skull and radiogrpahs in standard projections were performed and evaluated. It was obvious from the resulting radiographs that for most maxillofacial fractures a half axial or Water's view was most helpful. Lateral views only give additional information when there is a considerable degree of dislocation of fragments. Comparison with a prediatric skull of 8 years of age demonstrated that fractures of the zygomatic arch in this age group cannot be demonstrated by the typical submento-vertical view, but are shown on a Towne projection. The radiographic appearance of important maxillofacial fractures is demonstrated. The necessity of further studies in cases where reconstructive surgery appears necessary is discussed and CT rather then conventional tomography is advocated. (orig.) [de

  15. Collagen turnover after tibial fractures

    DEFF Research Database (Denmark)

    Joerring, S; Krogsgaard, M; Wilbek, H

    1994-01-01

    Collagen turnover after tibial fractures was examined in 16 patients with fracture of the tibial diaphysis and in 8 patients with fracture in the tibial condyle area by measuring sequential changes in serological markers of turnover of types I and III collagen for up to 26 weeks after fracture....... The markers were the carboxy-terminal extension peptide of type I procollagen (PICP), the amino-terminal extension peptide of type III procollagen (PIIINP), and the pyridinoline cross-linked carboxy-terminal telopeptide of type I collagen (ICTP). The latter is a new serum marker of degradation of type I...... collagen. A group comparison showed characteristic sequential changes in the turnover of types I and III collagen in fractures of the tibial diaphysis and tibial condyles. The turnover of type III collagen reached a maximum after 2 weeks in both groups. The synthesis of type I collagen reached a maximum...

  16. Computer simulation of ductile fracture

    International Nuclear Information System (INIS)

    Wilkins, M.L.; Streit, R.D.

    1979-01-01

    Finite difference computer simulation programs are capable of very accurate solutions to problems in plasticity with large deformations and rotation. This opens the possibility of developing models of ductile fracture by correlating experiments with equivalent computer simulations. Selected experiments were done to emphasize different aspects of the model. A difficult problem is the establishment of a fracture-size effect. This paper is a study of the strain field around notched tensile specimens of aluminum 6061-T651. A series of geometrically scaled specimens are tested to fracture. The scaled experiments are conducted for different notch radius-to-diameter ratios. The strains at fracture are determined from computer simulations. An estimate is made of the fracture-size effect

  17. Pathogenesis of osteoporotic hip fractures.

    Science.gov (United States)

    McClung, Michael R

    2003-01-01

    Osteoporosis is characterized late in the course of the disease by an increased risk of fracture, particularly in the elderly. It occurs in both sexes, affecting approximately 8 million women and 2 million men aged > or = 50 years (1). While low bone density is a predictor of fractures, it is not the only determinant of fracture risk. Other factors include advanced age, altered bone quality, a personal or family history of falls, frailty, poor eyesight, debilitating diseases, and high bone turnover. A diet with sufficient calcium and vitamin D is important to minimize bone loss and, along with regular exercise, to maintain muscle strength. Bisphosphonates have been shown to reduce the risk of hip fracture. For elderly patients, the use of hip protectors may be used as a treatment of last resort. Regardless of the age of the patient, individual patient risk factors must be considered to target appropriate treatment and prevent fracture.

  18. Physiological parameters

    International Nuclear Information System (INIS)

    Natera, E.S.

    1998-01-01

    The physiological characteristics of man depend on the intake, metabolism and excretion of stable elements from food, water, and air. The physiological behavior of natural radionuclides and radionuclides from nuclear weapons testing and from the utilization of nuclear energy is believed to follow the pattern of stable elements. Hence information on the normal physiological processes occurring in the human body plays an important role in the assessment of the radiation dose received by man. Two important physiological parameters needed for internal dose determination are the pulmonary function and the water balance. In the Coordinated Research Programme on the characterization of Asian population, five participants submitted data on these physiological characteristics - China, India, Japan, Philippines and Viet Nam. During the CRP, data on other pertinent characteristics such as physical and dietary were simultaneously being collected. Hence, the information on the physiological characteristics alone, coming from the five participants were not complete and are probably not sufficient to establish standard values for the Reference Asian Man. Nonetheless, the data collected is a valuable contribution to this research programme

  19. Relative Permeability of Fractured Rock

    Energy Technology Data Exchange (ETDEWEB)

    Mark D. Habana

    2002-06-30

    Contemporary understanding of multiphase flow through fractures is limited. Different studies using synthetic fractures and various fluids have yielded different relative permeability-saturation relations. This study aimed to extend the understanding of multiphase flow by conducting nitrogen-water relative permeability experiments on a naturally-fractured rock from The Geysers geothermal field. The steady-state approach was used. However, steady state was achieved only at the endpoint saturations. Several difficulties were encountered that are attributed to phase interference and changes in fracture aperture and surface roughness, along with fracture propagation/initiation. Absolute permeabilities were determined using nitrogen and water. The permeability values obtained change with the number of load cycles. Determining the absolute permeability of a core is especially important in a fractured rock. The rock may change as asperities are destroyed and fractures propagate or st rain harden as the net stresses vary. Pressure spikes occurred in water a solute permeability experiments. Conceptual models of an elastic fracture network can explain the pressure spike behavior. At the endpoint saturations the water relative permeabilities obtained are much less than the nitrogen gas relative permeabilities. Saturations were determined by weighing and by resistivity calculations. The resistivity-saturation relationship developed for the core gave saturation values that differ by 5% from the value determined by weighing. Further work is required to complete the relative permeability curve. The steady-state experimental approach encountered difficulties due to phase interference and fracture change. Steady state may not be reached until an impractical length of time. Thus, unsteady-state methods should be pursued. In unsteady-state experiments the challenge will be in quantifying rock fracture change in addition to fluid flow changes.

  20. Fracture behavior of human molars.

    Science.gov (United States)

    Keown, Amanda J; Lee, James J-W; Bush, Mark B

    2012-12-01

    Despite the durability of human teeth, which are able to withstand repeated loading while maintaining form and function, they are still susceptible to fracture. We focus here on longitudinal fracture in molar teeth-channel-like cracks that run along the enamel sidewall of the tooth between the gum line (cemento-enamel junction-CEJ) and the occlusal surface. Such fractures can often be painful and necessitate costly restorative work. The following study describes fracture experiments made on molar teeth of humans in which the molars are placed under axial compressive load using a hard indenting plate in order to induce longitudinal cracks in the enamel. Observed damage modes include fractures originating in the occlusal region ('radial-median cracks') and fractures emanating from the margin of the enamel in the region of the CEJ ('margin cracks'), as well as 'spalling' of enamel (the linking of longitudinal cracks). The loading conditions that govern fracture behavior in enamel are reported and observations made of the evolution of fracture as the load is increased. Relatively low loads were required to induce observable crack initiation-approximately 100 N for radial-median cracks and 200 N for margin cracks-both of which are less than the reported maximum biting force on a single molar tooth of several hundred Newtons. Unstable crack growth was observed to take place soon after and occurred at loads lower than those calculated by the current fracture models. Multiple cracks were observed on a single cusp, their interactions influencing crack growth behavior. The majority of the teeth tested in this study were noted to exhibit margin cracks prior to compression testing, which were apparently formed during the functional lifetime of the tooth. Such teeth were still able to withstand additional loading prior to catastrophic fracture, highlighting the remarkable damage containment capabilities of the natural tooth structure.

  1. Characterizing fractured rock for fluid-flow, geomechanical, and paleostress modeling: Methods and preliminary results from Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Barton, C.C.; Larsen, E.; Page, W.R.; Howard, T.M.

    1993-01-01

    Fractures have been characterized for fluid-flow, geomechanical, and paleostress modeling at three localities in the vicinity of drill hole USW G-4 at Yucca Mountain in southwestern Nevada. A method for fracture characterization is introduced that integrates mapping fracture-trace networks and quantifying eight fracture parameters: trace length, orientation, connectivity, aperture, roughness, shear offset, trace-length density, and mineralization. A complex network of fractures was exposed on three 214- to 260-m 2 pavements cleared of debris in the upper lithophysal unit of the Tiva Canyon Member of the Miocene Paint-brush Tuff. The pavements are two-dimensional sections through the three-dimensional network of strata-bound fractures. All fractures with trace lengths greater than 0.2 m were mapped and studied

  2. Applications of probabilistic fracture mechanics to FBR components

    International Nuclear Information System (INIS)

    Yagawa, Genki; Yoshimura, Shinobu; Takenaka, Makoto; Hojo, Kiminobu; Kaguchi, Hitoshi.

    1991-01-01

    A probabilistic fracture mechanics code PCCF which could analyze half-elliptical crack behavior in a plate under creep-fatigue condition using nonlinear fracture mechanics parameters was developed. The effects of bending stress level on failure probability was studied using the PCCF as test analyses. As the results, failure mode was leakage not break in all cases analyzed in this study. It is shown that leak probability is sensitive to stress level and increase rapidly around yield stress of materials. (J.P.N.)

  3. Low-frequency fluid waves in fractures and pipes

    Energy Technology Data Exchange (ETDEWEB)

    Korneev, Valeri

    2010-09-01

    Low-frequency analytical solutions have been obtained for phase velocities of symmetrical fluid waves within both an infinite fracture and a pipe filled with a viscous fluid. Three different fluid wave regimes can exist in such objects, depending on the various combinations of parameters, such as fluid density, fluid viscosity, walls shear modulus, channel thickness, and frequency. Equations for velocities of all these regimes have explicit forms and are verified by comparisons with the exact solutions. The dominant role of fractures in rock permeability at field scales and the strong amplitude and frequency effects of Stoneley guided waves suggest the importance of including these wave effects into poroelastic theories.

  4. Modeling biogechemical reactive transport in a fracture zone

    Energy Technology Data Exchange (ETDEWEB)

    Molinero, Jorge; Samper, Javier; Yang, Chan Bing, and Zhang, Guoxiang; Guoxiang, Zhang

    2005-01-14

    A coupled model of groundwater flow, reactive solute transport and microbial processes for a fracture zone of the Aspo site at Sweden is presented. This is the model of the so-called Redox Zone Experiment aimed at evaluating the effects of tunnel construction on the geochemical conditions prevailing in a fracture granite. It is found that a model accounting for microbially-mediated geochemical processes is able to reproduce the unexpected measured increasing trends of dissolved sulfate and bicarbonate. The model is also useful for testing hypotheses regarding the role of microbial processes and evaluating the sensitivity of model results to changes in biochemical parameters.

  5. Modeling biogeochemical reactive transport in a fracture zone

    International Nuclear Information System (INIS)

    Molinero, Jorge; Samper, Javier; Yang, Chan Bing; Zhang, Guoxiang; Guoxiang, Zhang

    2005-01-01

    A coupled model of groundwater flow, reactive solute transport and microbial processes for a fracture zone of the Aspo site at Sweden is presented. This is the model of the so-called Redox Zone Experiment aimed at evaluating the effects of tunnel construction on the geochemical conditions prevailing in a fracture granite. It is found that a model accounting for microbially-mediated geochemical processes is able to reproduce the unexpected measured increasing trends of dissolved sulfate and bicarbonate. The model is also useful for testing hypotheses regarding the role of microbial processes and evaluating the sensitivity of model results to changes in biochemical parameters

  6. Mortality Following Periprosthetic Proximal Femoral Fractures Versus Native Hip Fractures.

    Science.gov (United States)

    Boylan, Matthew R; Riesgo, Aldo M; Paulino, Carl B; Slover, James D; Zuckerman, Joseph D; Egol, Kenneth A

    2018-04-04

    The number of periprosthetic proximal femoral fractures is expected to increase with the increasing prevalence of hip arthroplasties. While native hip fractures have a well-known association with mortality, there are currently limited data on this outcome among the subset of patients with periprosthetic proximal femoral fractures. Using the New York Statewide Planning and Research Cooperative System, we identified patients from 60 to 99 years old who were admitted to a hospital in the state with a periprosthetic proximal femoral fracture (n = 1,655) or a native hip (femoral neck or intertrochanteric) fracture (n = 97,231) between 2006 and 2014. Within the periprosthetic fracture cohort, the indication for the existing implant was not available in the data set. We used mixed-effects regression models to compare mortality at 1 and 6 months and 1 year for periprosthetic compared with native hip fractures. The risk of mortality for patients who sustained a periprosthetic proximal femoral fracture was no different from that for patients who sustained a native hip fracture at 1 month after injury (3.2% versus 4.6%; odds ratio [OR], 0.90; 95% confidence interval [CI], 0.68 to 1.19; p = 0.446), but was lower at 6 months (3.8% versus 6.5%; OR, 0.74; 95% CI, 0.57 to 0.95; p = 0.020) and 1 year (9.7% versus 15.9%; OR, 0.71; 95% CI, 0.60 to 0.85; p accounting for age and comorbidities. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

  7. A Rare Entity: Bilateral First Rib Fractures Accompanying Bilateral Scapular Fractures

    Directory of Open Access Journals (Sweden)

    Gultekin Gulbahar

    2015-01-01

    Full Text Available First rib fractures are scarce due to their well-protected anatomic locations. Bilateral first rib fractures accompanying bilateral scapular fractures are very rare, although they may be together with scapular and clavicular fractures. According to our knowledge, no case of bilateral first rib fractures accompanying bilateral scapular fractures has been reported, so we herein discussed the diagnosis, treatment, and complications of bone fractures due to thoracic trauma in bias of this rare entity.

  8. A Rare Entity: Bilateral First Rib Fractures Accompanying Bilateral Scapular Fractures

    OpenAIRE

    Gulbahar, Gultekin; Kaplan, Tevfik; Turker, Hasan Bozkurt; Gundogdu, Ahmet Gokhan; Han, Serdar

    2015-01-01

    First rib fractures are scarce due to their well-protected anatomic locations. Bilateral first rib fractures accompanying bilateral scapular fractures are very rare, although they may be together with scapular and clavicular fractures. According to our knowledge, no case of bilateral first rib fractures accompanying bilateral scapular fractures has been reported, so we herein discussed the diagnosis, treatment, and complications of bone fractures due to thoracic trauma in bias of this rare en...

  9. A Rare Entity: Bilateral First Rib Fractures Accompanying Bilateral Scapular Fractures.

    Science.gov (United States)

    Gulbahar, Gultekin; Kaplan, Tevfik; Turker, Hasan Bozkurt; Gundogdu, Ahmet Gokhan; Han, Serdar

    2015-01-01

    First rib fractures are scarce due to their well-protected anatomic locations. Bilateral first rib fractures accompanying bilateral scapular fractures are very rare, although they may be together with scapular and clavicular fractures. According to our knowledge, no case of bilateral first rib fractures accompanying bilateral scapular fractures has been reported, so we herein discussed the diagnosis, treatment, and complications of bone fractures due to thoracic trauma in bias of this rare entity.

  10. Evaluation of the conservativeness of the methodology for estimating earthquake-induced movements of fractures intersecting canisters

    International Nuclear Information System (INIS)

    La Pointe, Paul R.; Cladouhos, Trenton T.; Outters, Nils; Follin, Sven

    2000-04-01

    This study evaluates the parameter sensitivity and the conservativeness of the methodology outlined in TR 99-03. Sensitivity analysis focuses on understanding how variability in input parameter values impacts the calculated fracture displacements. These studies clarify what parameters play the greatest role in fracture movements, and help define critical values of these parameters in terms of canister failures. The thresholds or intervals of values that lead to a certain level of canister failure calculated in this study could be useful for evaluating future candidate sites. Key parameters include: 1. magnitude/frequency of earthquakes; 2. the distance of the earthquake from the canisters; 3. the size and aspect ratio of fractures intersecting canisters; and 4. the orientation of the fractures. The results of this study show that distance and earthquake magnitude are the most important factors, followed by fracture size. Fracture orientation is much less important. Regression relations were developed to predict induced fracture slip as a function of distance and either earthquake magnitude or slip on the earthquake fault. These regression relations were validated by using them to estimate the number of canister failures due to single damaging earthquakes at Aberg, and comparing these estimates with those presented in TR 99-03. The methodology described in TR 99-03 employs several conservative simplifications in order to devise a numerically feasible method to estimate fracture movements due to earthquakes outside of the repository over the next 100,000 years. These simplifications include: 1. fractures are assumed to be frictionless and cohesionless; 2. all energy transmitted to the fracture by the earthquake is assumed to produce elastic deformation of the fracture; no energy is diverted into fracture propagation; and 3. shielding effects of other fractures between the earthquake and the fracture are neglected. The numerical modeling effectively assumes that the

  11. Evaluation of the conservativeness of the methodology for estimating earthquake-induced movements of fractures intersecting canisters

    Energy Technology Data Exchange (ETDEWEB)

    La Pointe, Paul R.; Cladouhos, Trenton T. [Golder Associates Inc., Las Vegas, NV (United States); Outters, Nils; Follin, Sven [Golder Grundteknik KB, Stockholm (Sweden)

    2000-04-01

    This study evaluates the parameter sensitivity and the conservativeness of the methodology outlined in TR 99-03. Sensitivity analysis focuses on understanding how variability in input parameter values impacts the calculated fracture displacements. These studies clarify what parameters play the greatest role in fracture movements, and help define critical values of these parameters in terms of canister failures. The thresholds or intervals of values that lead to a certain level of canister failure calculated in this study could be useful for evaluating future candidate sites. Key parameters include: 1. magnitude/frequency of earthquakes; 2. the distance of the earthquake from the canisters; 3. the size and aspect ratio of fractures intersecting canisters; and 4. the orientation of the fractures. The results of this study show that distance and earthquake magnitude are the most important factors, followed by fracture size. Fracture orientation is much less important. Regression relations were developed to predict induced fracture slip as a function of distance and either earthquake magnitude or slip on the earthquake fault. These regression relations were validated by using them to estimate the number of canister failures due to single damaging earthquakes at Aberg, and comparing these estimates with those presented in TR 99-03. The methodology described in TR 99-03 employs several conservative simplifications in order to devise a numerically feasible method to estimate fracture movements due to earthquakes outside of the repository over the next 100,000 years. These simplifications include: 1. fractures are assumed to be frictionless and cohesionless; 2. all energy transmitted to the fracture by the earthquake is assumed to produce elastic deformation of the fracture; no energy is diverted into fracture propagation; and 3. shielding effects of other fractures between the earthquake and the fracture are neglected. The numerical modeling effectively assumes that the

  12. Fracture flow code

    International Nuclear Information System (INIS)

    Dershowitz, W; Herbert, A.; Long, J.

    1989-03-01

    The hydrology of the SCV site will be modelled utilizing discrete fracture flow models. These models are complex, and can not be fully cerified by comparison to analytical solutions. The best approach for verification of these codes is therefore cross-verification between different codes. This is complicated by the variation in assumptions and solution techniques utilized in different codes. Cross-verification procedures are defined which allow comparison of the codes developed by Harwell Laboratory, Lawrence Berkeley Laboratory, and Golder Associates Inc. Six cross-verification datasets are defined for deterministic and stochastic verification of geometric and flow features of the codes. Additional datasets for verification of transport features will be documented in a future report. (13 figs., 7 tabs., 10 refs.) (authors)

  13. Uncertainty Characterization of Reactor Vessel Fracture Toughness

    International Nuclear Information System (INIS)

    Li, Fei; Modarres, Mohammad

    2002-01-01

    To perform fracture mechanics analysis of reactor vessel, fracture toughness (K Ic ) at various temperatures would be necessary. In a best estimate approach, K Ic uncertainties resulting from both lack of sufficient knowledge and randomness in some of the variables of K Ic must be characterized. Although it may be argued that there is only one type of uncertainty, which is lack of perfect knowledge about the subject under study, as a matter of practice K Ic uncertainties can be divided into two types: aleatory and epistemic. Aleatory uncertainty is related to uncertainty that is very difficult to reduce, if not impossible; epistemic uncertainty, on the other hand, can be practically reduced. Distinction between aleatory and epistemic uncertainties facilitates decision-making under uncertainty and allows for proper propagation of uncertainties in the computation process. Typically, epistemic uncertainties representing, for example, parameters of a model are sampled (to generate a 'snapshot', single-value of the parameters), but the totality of aleatory uncertainties is carried through the calculation as available. In this paper a description of an approach to account for these two types of uncertainties associated with K Ic has been provided. (authors)

  14. Computational aspects of nonlinear fracture mechanics

    International Nuclear Information System (INIS)

    Brocks, W.; Cornec, A.; Scheider, I.

    2003-01-01

    The following contribution will essentially restrict to the application of the von Mises theory of incremental plasticity to cracked specimens and components. In particular, the classical parameters of EPFM, J and CTOD, as well as subsequently proposed parameters such as energy dissipation rate and crack-tip opening angle (CTOA) and the related computational aspects will be discussed. Some remarks follow on the 'local approach to fracture' which is based on continuum field quantities, namely stresses and strains, and the damage models of Gurson (1977) and Rousselier (1987), which have now found increasing application, will be briefly addressed in Section 3.03.4. The numerical modeling of decohesion and separation phenomena by 'cohesive elements' will be presented in Section 3.03.5. (orig.)

  15. 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

  16. Tracer transport in fractured rocks

    International Nuclear Information System (INIS)

    Tsang, C.F.; Tsang, Y.W.; Hale, F.V.

    1988-07-01

    Recent interest in the safety of toxic waste underground disposal and nuclear waste geologic repositories has motivated many studies of tracer transport in fractured media. Fractures occur in most geologic formations and introduce a high degree of heterogeneity. Within each fracture, the aperture is not constant in value but strongly varying. Thus for such media, tracer tends to flow through preferred flowpaths or channels within the fractures. Along each of these channels, the aperture is also strongly varying. A detailed analysis is carried out on a 2D single fracture with variable apertures and the flow through channels is demonstrated. The channels defined this way are not rigidly set pathways for tracer transport, but are the preferred flow paths in the sense of stream-tubes in the potential theory. It is shown that such variable-aperture channels can be characterized by an aperture probability distribution function, and not by the exact deterministic geometric locations. We also demonstrate that the 2D tracer transport in a fracture can be calculated by a model of a system of 1D channels characterized by this distribution function only. Due to the channeling character of tracer transport in fractured rock, random point measurements of tracer breakthrough curves may give results with a wide spread in value due to statistical fluctuations. The present paper suggests that such a wide spread can probably be greatly reduced by making line/areal (or multiple) measurements covering a few spatial correlation lengths. 13 refs., 11 figs., 1 tab

  17. Statistical methodology for discrete fracture model - including fracture size, orientation uncertainty together with intensity uncertainty and variability

    International Nuclear Information System (INIS)

    Darcel, C.; Davy, P.; Le Goc, R.; Dreuzy, J.R. de; Bour, O.

    2009-11-01

    Investigations led for several years at Laxemar and Forsmark reveal the large heterogeneity of geological formations and associated fracturing. This project aims at reinforcing the statistical DFN modeling framework adapted to a site scale. This leads therefore to develop quantitative methods of characterization adapted to the nature of fracturing and data availability. We start with the hypothesis that the maximum likelihood DFN model is a power-law model with a density term depending on orientations. This is supported both by literature and specifically here by former analyses of the SKB data. This assumption is nevertheless thoroughly tested by analyzing the fracture trace and lineament maps. Fracture traces range roughly between 0.5 m and 10 m - i e the usual extension of the sample outcrops. Between the raw data and final data used to compute the fracture size distribution from which the size distribution model will arise, several steps are necessary, in order to correct data from finite-size, topographical and sampling effects. More precisely, a particular attention is paid to fracture segmentation status and fracture linkage consistent with the DFN model expected. The fracture scaling trend observed over both sites displays finally a shape parameter k t close to 1.2 with a density term (α 2d ) between 1.4 and 1.8. Only two outcrops clearly display a different trend with k t close to 3 and a density term (α 2d ) between 2 and 3.5. The fracture lineaments spread over the range between 100 meters and a few kilometers. When compared with fracture trace maps, these datasets are already interpreted and the linkage process developed previously has not to be done. Except for the subregional lineament map from Forsmark, lineaments display a clear power-law trend with a shape parameter k t equal to 3 and a density term between 2 and 4.5. The apparent variation in scaling exponent, from the outcrop scale (k t = 1.2) on one side, to the lineament scale (k t = 2) on

  18. Fracture Behavior and Properties of Functionally Graded Fiber-Reinforced Concrete

    International Nuclear Information System (INIS)

    Roesler, Jeffery; Bordelon, Amanda; Gaedicke, Cristian; Park, Kyoungsoo; Paulino, Glaucio

    2008-01-01

    In concrete pavements, a single concrete mixture design is selected to resist mechanical loading without attempting to adversely affect the concrete pavement shrinkage, ride quality, or noise attenuation. An alternative approach is to design distinct layers within the concrete pavement surface which have specific functions thus achieving higher performance at a lower cost. The objective of this research was to address the structural benefits of functionally graded concrete materials (FGCM) for rigid pavements by testing and modeling the fracture behavior of different combinations of layered plain and synthetic fiber-reinforced concrete materials. Fracture parameters and the post-peak softening behavior were obtained for each FGCM beam configuration by the three point bending beam test. The peak loads and initial fracture energy between the plain, fiber-reinforced, and FGCM signified similar crack initiation. The total fracture energy indicated improvements in fracture behavior of FGCM relative to full-depth plain concrete. The fracture behavior of FGCM depended on the position of the fiber-reinforced layer relative to the starter notch. The fracture parameters of both fiber-reinforced and plain concrete were embedded into a finite element-based cohesive zone model. The model successfully captured the experimental behavior of the FGCMs and predicted the fracture behavior of proposed FGCM configurations and structures. This integrated approach (testing and modeling) demonstrates the viability of FGCM for designing layered concrete pavements system

  19. Numerical modelling of single-phase flow in rough fractures with contacts

    Science.gov (United States)

    Olkiewicz, Piotr; Dabrowski, Marcin

    2017-04-01

    Fracture flow may dominate in rocks with low porosity and it can accompany both industrial and natural processes. Typical examples of such processes are natural flows in crystalline rocks and industrial flows in oil and gas production systems or hydraulic fracturing. Fracture flow provides an important mechanism for transporting mass and energy. The distribution of the apertures of fracture and contact area are the key parameters with regard to the fracture transmissivity. We use the method of correlated random fields [Mourzenko, 1996] to generate synthetic fracture geometry in 3D. The flow of an incompressible Newtonian viscous fluid in geological formation can be approximated by the Stokes, the Stokes-Brinkman or the Reynolds models. We use our own implementation of the finite element method based on MILAMIN [Dabrowski, 2008] to solve governing partial differential equation over domain. We compare the Stokes, the Stokes-Brinkamn and the Reynolds models for fracture flow based on systematic numerical simulations for a wide range of geometric parameters. Mismatch between the Reynolds and the Stokes models becomes significant with increasing fracture roughness or contact area. The Stokes-Brinkman model is more accurate than Reynolds models due to additional Laplacian term, which allows to fulfil no-slip boundary condition. We present condition when the Reynolds and the Stokes-Brinkman models are valid. In the last three decades many authors used the Reynolds equation for studying fracture flow because of its simplicity. We recommend using the Stokes-Brinkman model for fracture flow, which allows to fulfil no-slip boundary condition on asperities boundary and is more accurate for rough fractures than the Reynolds model.

  20. Stress fractures and bone pain

    International Nuclear Information System (INIS)

    Groshar, D.; Even-Sapir, E.; Lam, M.; Israel, O.; Front, D.

    1984-01-01

    Stress fractures result from an unusual repetitive physical activity causing absorption of bone in excess of repair and bone formation. This leads to the weakening of the bone and subsequently to a fracture. It is a benign condition that if recognized in time does not need any treatment besides rest. However, if diagnosis is not made and physical activity continues it may result in severe injury to the bone and a frank fracture may result. Pain is the typical clinical feature and bone scintigraphy, being more sensitive than radiography, is done to establish early diagnosis. The presence of asymptomatic sites of abnormal bone uptake typical of stress fracture in which pain appeared only about 2 weeks after scintigraphy, drew the authors' attention to the question of how close is the relationship between stress fractures and bone pain. Sixty-four military recruits diagnosed as suffering from stress fracture were investigated in order to correlate sites with abnormal uptake of Tc-99m MDP on bone scintigraphy with sites of local pain. In 37 (58%) subjects multiple sites of abnormal uptake were recognised. Of 123 sites of abnormal uptake, 31 (25%) were asymptomatic. In three patients bone pain appeared at the site of the abnormal uptake two weeks after scintigraphy. Bone scintigraphy appears to be more sensitive than bone pain in the diagnosis of stress fractures. The osteoblastic activity which manifests itself by abnormal uptake appears in some cases earlier than the pain caused by the fracture. Present findings may suggest that under certain circumstances, in a population prone to stress fracture, bone scan should be considered as a screening method