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Sample records for reliably resisting delamination

  1. Delamination Detection in Carbon Fibre Reinforced Composites Using Electrical Resistance Measurement

    International Nuclear Information System (INIS)

    Kovalovs, A; Rucevskis, S; Kulakov, V; Aniskevich, A

    2016-01-01

    In the present study 2-D numerical analysis of strip-type laminated composite specimens with and without damage is considered and numerical investigation is carried out by using a finite element method. The surface and oblique resistances are numerically calculated according to the two-probe and four-probe methods. The electrical conductivity of the composite laminate in the longitudinal direction is constant, while the electrical conductivity in the through-thickness direction is used as a variable in the parametric study. The resistance change due to delamination for each case is estimated by comparing the obtained resistance with the corresponding resistance of the specimen without delamination. Applicability and effectiveness of the proposed method are investigated by using various lengths of a delaminated crack in the specimen. (paper)

  2. Delamination of Composite Cylinders

    Science.gov (United States)

    Davies, Peter; Carlsson, Leif A.

    The delamination resistance of filament wound glass/epoxy cylinders has been characterized for a range of winding angles and fracture mode ratios using beam fracture specimens. The results reveal that the delamination fracture resistance increases with increasing winding angle and mode II (shear) fraction (GΠ/G). It was also found that interlaced fiber bundles in the filament wound cylinder wall acted as effective crack arresters in mode I loading. To examine the sensitivity of delamina-tion damage on the strength of the cylinders, external pressure tests were performed on filament-wound glass/epoxy composite cylinders with artificial defects and impact damage. The results revealed that the cylinder strength was insensitive to the presence of single delaminations but impact damage caused reductions in failure pressure. The insensitivity of the failure pressure to a single delamination is attributed to the absence of buckling of the delaminated sublaminates before the cylinder wall collapsed. The impacted cylinders contained multiple delaminations, which caused local reduction in the compressive load capability and reduction in failure pressure. The response of glass/epoxy cylinders was compared to impacted carbon reinforced cylinders. Carbon/epoxy is more sensitive to damage but retains higher implosion resistance while carbon/PEEK shows the opposite trend.

  3. The coupled effects of thickness and delamination on cracking resistance of X70 pipeline steel

    International Nuclear Information System (INIS)

    Guo, W.; Dong, H.; Lu, M.; Zhao, X.

    2002-01-01

    The effects of thickness and delamination on the fracture toughness and stable crack growth behaviour of high-toughness pipeline steels were investigated experimentally by use of compact tension specimens with thicknesses of 3-15 mm cut from a 17 mm-thick wall pipe. Material resistance curves were generated based on the stress intensity factor (SIF) K and the J-integral. The critical SIF K c and the J-resistance curves are found to be independent of thickness as the delaminations near the crack tip within the material reduce the out-of-plane constraint in thicker specimens. Both fracture mechanism and mechanics analyses shown that the fracture behaviour of the steel is controlled by the strong-coupled effects of thickness and delaminations. With increasing thickness, the out-of-plane stress constraint increases and causes the inclusion separation, growth and coalescence to form delaminations of different sizes before the main crack initiates. The delaminations in turn, reduce the out-of-plane constraint and thus, the thickness effect upon fracture. The advantages and disadvantages of delaminations in a safety assessment of pipelines are also discussed based on three-dimensional fracture theory

  4. Delamination Resistance Of Laminate Made With VBO MTM46/HTS Prepreg

    Directory of Open Access Journals (Sweden)

    Czarnocki Piotr

    2015-09-01

    Full Text Available A laminate made with the Vacuum Bag Only (VBO prepregs can be cured out of autoclave. Because of low curing pressure such a process can result in deterioration of laminate mechanical properties. They can be significantly lower than those displayed by the autoclave cured ones. The resistance against delamination can be among the most affected. Since this property is a week point of all the laminates it was of particular interest. Delamination resistance of unidirectional laminate made from VBO MTM46/HTS(12K prepreg was in the scope of the presented research and the critical values of the Strain Energy Release Rates and the Paris-type equations corresponding to Mode I, Mode II and Mixed-Mode I/II static and cyclic loadings, respectively, were determined.

  5. Surface modification of carbon/epoxy prepreg using oxygen plasma and its effect on the delamination resistance behavior of carbon/epoxy composites

    International Nuclear Information System (INIS)

    Kim, M.H.; Rhee, K.Y.; Kim, H.J.; Jung, D.H.

    2007-01-01

    It was shown in previous study that the fracture toughness of carbon/epoxy laminated composites could be significantly improved by modifying the surface of the prepreg using Ar + irradiation in an oxygen environment. In this study, the surface of carbon/epoxy prepreg was modified using an oxygen plasma to improve the delamination resistance behavior of carbon/epoxy laminated composites. The variation of the contact angle on the prepreg surface was determined as a function of the modification time, in order to determine the optimal modification time. An XPS analysis was conducted to investigate the chemical changes on the surface of the prepreg caused by the plasma modification. Mode I delamination resistance curves of the composites with and without surface modification were plotted as a function of the delamination increment. The results showed that the contact angle varied from ∼64 o to ∼47 o depending on the modification time and reached a minimum for a modification time of 30 min. The XPS analysis showed that the hydrophilic carbonyl C=O group was formed by the oxygen plasma modification. The results also showed that the delamination resistance behavior was significantly improved by the plasma modification of the prepreg. This improvement was caused by the better layer-to-layer adhesion as well as increased interfacial strength between the fibers and matrix

  6. An in-situ experimental-numerical approach for interface delamination characterization

    NARCIS (Netherlands)

    Murthy Kolluri, N.V.V.R.

    2011-01-01

    Interfacial delamination is a key reliability challenge in composites and microelectronic systems due to (high density) integration of dissimilar materials. Delamination occurs due to significant stresses generated at the interfaces, for instance, caused by thermal cycling due to the mismatch in

  7. The effect of nylon nanofibers on the dynamic behaviour and the delamination resistance of GFRP composites

    Directory of Open Access Journals (Sweden)

    Garcia Cristobal

    2018-01-01

    Full Text Available Vibrations are responsible for a considerable number of accidents in aircrafts, bridges and other civil engineering structures. Therefore, there is a need to reduce the vibrations on structures made of composite materials. Delamination is a particularly dangerous failure mode for composite materials because delaminated composites can lose up to 60% of their strength and stiffness and still remain unchanged. One of the methods to suppress vibrations and preventing delamination is to incorporate nanofibers into the composite laminates. The aim of the present work is to investigate how nylon nanofibers affect the dynamic behaviour and delamination resistance of glass fibre reinforced polymer (GFRP composites. Experiments and numerical simulations using finite element modelling (FEM analysis are used to estimate the natural frequencies, the damping ratio and inter-laminar strength in GFRP composites with and without nylon nanofibers. It is found that the natural frequencies of the nylon nano-modified composites do not change significantly as compared to the traditional composites. However, nano-modified composites demonstrated a considerable increase in damping ratio and inter-laminar shear strength due to the incorporation of nylon nanofibers. This work contributes to the knowledge about the mechanical and dynamic properties of glass fibre reinforced polymer (GFRP composites with nylon nanofibers.

  8. Finite elements modeling of delaminations in composite laminates

    DEFF Research Database (Denmark)

    Gaiotti, m.; Rizzo, C.M.; Branner, Kim

    2011-01-01

    of the buckling strength of composite laminates containing delaminations. Namely, non-linear buckling and post-buckling analyses are carried out to predict the critical buckling load of elementary composite laminates affected by rectangular delaminations of different sizes and locations, which are modelled......The application of composite materials in many structures poses to engineers the problem to create reliable and relatively simple methods, able to estimate the strength of multilayer composite structures. Multilayer composites, like other laminated materials, suffer from layer separation, i.......e., delaminations, which may affect the stiffness and stability of structural components. Especially deep delaminations in the mid surface of laminates are expected to reduce the effective flexural stiffness and lead to collapse, often due to buckling behaviour. This paper deals with the numerical modelling...

  9. Non-destructive delamination detection in solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Gazzarri, J.I.; Kesler, O. [Department of Mechanical Engineering, University of British Columbia, 2054-6250 Applied Science Lane, Vancouver, BC V6T 1Z4 (Canada)

    2007-05-15

    A finite element model has been developed to simulate the steady state and impedance behaviour of a single operating solid oxide fuel cell (SOFC). The model results suggest that electrode delamination can be detected minimally-invasively by using electrochemical impedance spectroscopy. The presence of cathode delamination causes changes in the cell impedance spectrum that are characteristic of this type of degradation mechanism. These changes include the simultaneous increase in both the series and polarization resistances, in proportion to the delaminated area. Parametric studies show the dependence of these changes on the extent of delamination, on the operating point, and on the kinetic characteristics of the fuel cell under study. (author)

  10. Integrated global digital image correlation for interface delamination characterization

    KAUST Repository

    Hoefnagels, Johan P.M.

    2013-07-23

    Interfacial delamination is a key reliability challenge in composites and micro-electronic systems due to (high-density) integration of dissimilar materials. Predictive finite element models are used to minimize delamination failures during design, but require accurate interface models to capture (irreversible) crack initiation and propagation behavior observed in experiments. Therefore, an Integrated Global Digital Image Correlation (I-GDIC) strategy is developed for accurate determination of mechanical interface behavior from in-situ delamination experiments. Recently, a novel miniature delamination setup was presented that enables in-situ microscopic characterization of interface delamination while sensitively measuring global load-displacement curves for all mode mixities. Nevertheless, extraction of detailed mechanical interface behavior from measured images is challenging, because deformations are tiny and measurement noise large. Therefore, an advanced I-GDIC methodology is developed which correlates the image patterns by only deforming the images using kinematically-admissible \\'eigenmodes\\' that correspond to the few parameters controlling the interface tractions in an analytic description of the crack tip deformation field, thereby greatly enhancing accuracy and robustness. This method is validated on virtual delamination experiments, simulated using a recently developed self-adaptive cohesive zone (CZ) finite element framework. © The Society for Experimental Mechanics, Inc. 2014.

  11. Guided Wave Delamination Detection and Quantification With Wavefield Data Analysis

    Science.gov (United States)

    Tian, Zhenhua; Campbell Leckey, Cara A.; Seebo, Jeffrey P.; Yu, Lingyu

    2014-01-01

    Unexpected damage can occur in aerospace composites due to impact events or material stress during off-nominal loading events. In particular, laminated composites are susceptible to delamination damage due to weak transverse tensile and inter-laminar shear strengths. Developments of reliable and quantitative techniques to detect delamination damage in laminated composites are imperative for safe and functional optimally-designed next-generation composite structures. In this paper, we investigate guided wave interactions with delamination damage and develop quantification algorithms by using wavefield data analysis. The trapped guided waves in the delamination region are observed from the wavefield data and further quantitatively interpreted by using different wavenumber analysis methods. The frequency-wavenumber representation of the wavefield shows that new wavenumbers are present and correlate to trapped waves in the damage region. These new wavenumbers are used to detect and quantify the delamination damage through the wavenumber analysis, which can show how the wavenumber changes as a function of wave propagation distance. The location and spatial duration of the new wavenumbers can be identified, providing a useful means not only for detecting the presence of delamination damage but also allowing for estimation of the delamination size. Our method has been applied to detect and quantify real delamination damage with complex geometry (grown using a quasi-static indentation technique). The detection and quantification results show the location, size, and shape of the delamination damage.

  12. Delaminated sodium nonatitanate and a method for producing delaminated sodium nonatitanate

    Science.gov (United States)

    Nyman, May D.

    2016-02-02

    A hydrothermal synthesis method of making a delaminated titanate is disclosed. The delaminated titanate has a unique structure or morphology. The delaminated titanate is first formed by forming at a low temperature a layered sodium nonatitanate (SNT), which may be referred to as layered sodium titanate. The layered SNT has a unique morphology. The layered SNT is then synthesized into a delaminated titanate having a unique morphology.

  13. Delaminated rotator cuff tear: extension of delamination and cuff integrity after arthroscopic rotator cuff repair.

    Science.gov (United States)

    Gwak, Heui-Chul; Kim, Chang-Wan; Kim, Jung-Han; Choo, Hye-Jeung; Sagong, Seung-Yeob; Shin, John

    2015-05-01

    The purpose of this study was to evaluate the extension of delamination and the cuff integrity after arthroscopic repair of delaminated rotator cuff tears. Sixty-five patients with delaminated rotator cuff tears were retrospectively reviewed. The delaminated tears were divided into full-thickness delaminated tears and partial-thickness delaminated tears. To evaluate the medial extension, we calculated the coronal size of the delaminated portion. To evaluate the posterior extension, we checked the tendon involved. Cuff integrity was evaluated by computed tomography arthrography. The mean medial extension in the full-thickness and partial-thickness delaminated tears was 18.1 ± 6.0 mm and 22.7 ± 6.3 mm, respectively (P = .0084). The posterior extension into the supraspinatus and the infraspinatus was 36.9% and 32.3%, respectively, in the full-thickness delaminated tears, and it was 27.7% and 3.1%, respectively, in the partial-thickness delaminated tears (P = .0043). With regard to cuff integrity, 35 cases of anatomic healing, 10 cases of partial healing defects, and 17 cases of retear were detected. Among the patients with retear and partial healing of the defect, all the partially healed defects showed delamination. Three retear patients showed delamination, and 14 retear patients did not show delamination; the difference was statistically significant (P = .0001). The full-thickness delaminated tears showed less medial extension and more posterior extension than the partial-thickness delaminated tears. Delamination did not develop in retear patients, but delamination was common in the patients with partially healed defects. Copyright © 2015 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  14. Delamination R-curve as a material property of unidirectional glass/epoxy composites

    International Nuclear Information System (INIS)

    Shokrieh, M.M.; Heidari-Rarani, M.; Ayatollahi, M.R.

    2012-01-01

    Highlights: → The R-curve behavior of a unidirectional laminate as a material property is investigated. → Effect of initial crack length and thickness on R-curve is experimentally shown. → A mathematical relation is proposed to model the R-curve behavior of any unidirectional laminated composite. -- Abstract: It is still questionable to think of delamination resistance of a double cantilever beam (DCB) as a material property independent of the specimen size and geometry. In this research, the effects of initial crack length and DCB specimen thickness on the mode I delamination resistance curve (R-curve) behavior of different unidirectional glass/epoxy DCB specimens are experimentally investigated. It is observed that the magnitudes of initiation and propagation delamination toughness (G Ic-init and G Ic-prop ) as well as the fiber bridging length are constant in a specific range of the initial crack length to the DCB specimen thickness ratios of 8.5 0 /h < 19. Finally, a mathematical relationship is proposed for prediction of mode I delamination behavior (from the initiation to propagation) of E-glass/epoxy DCB specimens.

  15. To improve impact damage response of single and multi-delaminated FRP composites using natural Flax yarn

    International Nuclear Information System (INIS)

    Ghasemnejad, H.; Soroush, V.R.; Mason, P.J.; Weager, B.

    2012-01-01

    Highlights: ► To study the impact resistance of delaminated composite structures. ► To improve the impact resistance of delaminated composite structures using natural Flax yarn. ► To investigate the effect of z-pinning on the damage process of composite materials. ► To develop FE techniques to model the impact process of composite structures using LSDYNA. -- Abstract: The ply delamination which is known as a principle mode of failure of layered composites due to separation along the interfaces of the layers is one of the main concerns in designing of composite material structures. In this regard, the effect of hybrid laminate lay-up in multi-delaminated composite beam was investigated. The Charpy impact test was chosen to study the energy absorbing capability of delaminated composite beam. Hybrid composite beams were fabricated from combination of glass/epoxy and carbon/epoxy composites. To improve the impact behaviour of multi-delaminated composite beams the laminated hybrid composite beams were pinned using Flax yarns before curing process. It was shown that the multi-delaminated composite beams which are pinned in z-direction are able to arrest the crack propagation and consequently absorb more energy in comparison with simple ones in hybrid composite beams. The Charpy impact test of delaminated composite beams was also simulated by finite element software LS-DYNA and the results were verified with the relevant experimental results.

  16. Quantitative Evaluation of Delamination in Composites Using Lamb Waves

    Science.gov (United States)

    Michalcová, L.; Hron, R.

    2018-03-01

    Ultrasonic guided wave monitoring has become very popular in the area of structural health monitoring (SHM) of aerospace structures. Any possible type of damage must be reliably assessed. The paper deals with delamination length determination in DCB specimens using Lamb waves. An analytical equation based on the velocity dependence on variable thickness is utilized. The group velocity of the fundamental antisymmetric A0 mode rapidly changes in a particular range of the frequency-thickness product. Using the same actuation frequency the propagation velocity is different for delaminated structure. Lamb wave based delamination lengths were compared to the visually determined lengths. The method of the wave velocity determination proved to be essential. More accurate results were achieved by tracking the maximum amplitude of A0 mode than the first signal arrival. These findings are considered as the basis for the damage evaluation of complex structures.

  17. Reduction of cathodic delamination rates of anticorrosive coatings using free radical scavengers

    DEFF Research Database (Denmark)

    Sørensen, Per Aggerholm; Weinell, C. E.; Dam-Johansen, Kim

    2010-01-01

    Cathodic delamination is one of the major modes of failure for anticorrosive coatings subjected to a physical damage and immersed in seawater. The cause of cathodic delamination has been reported to be the result of a chemical attack at the coating-steel interface by free radicals and peroxides...... formed as intermediates in the cathodic reaction during the corrosion process. In this study, antioxidants (i.e., free radical scavengers and peroxide decomposers) have been incorporated into various generic types of coatings to investigate the effect of antioxidants on the rate of cathodic delamination...... of epoxy coatings on cold rolled steel. The addition of free radical scavengers to epoxy coatings improved the resistance toward cathodic delamination by up to 50% during seawater immersion, while peroxide decomposers had a limited effect. Testing using substrates prepared from stainless steel...

  18. Delamination detection using methods of computational intelligence

    Science.gov (United States)

    Ihesiulor, Obinna K.; Shankar, Krishna; Zhang, Zhifang; Ray, Tapabrata

    2012-11-01

    Abstract Reliable delamination prediction scheme is indispensable in order to prevent potential risks of catastrophic failures in composite structures. The existence of delaminations changes the vibration characteristics of composite laminates and hence such indicators can be used to quantify the health characteristics of laminates. An approach for online health monitoring of in-service composite laminates is presented in this paper that relies on methods based on computational intelligence. Typical changes in the observed vibration characteristics (i.e. change in natural frequencies) are considered as inputs to identify the existence, location and magnitude of delaminations. The performance of the proposed approach is demonstrated using numerical models of composite laminates. Since this identification problem essentially involves the solution of an optimization problem, the use of finite element (FE) methods as the underlying tool for analysis turns out to be computationally expensive. A surrogate assisted optimization approach is hence introduced to contain the computational time within affordable limits. An artificial neural network (ANN) model with Bayesian regularization is used as the underlying approximation scheme while an improved rate of convergence is achieved using a memetic algorithm. However, building of ANN surrogate models usually requires large training datasets. K-means clustering is effectively employed to reduce the size of datasets. ANN is also used via inverse modeling to determine the position, size and location of delaminations using changes in measured natural frequencies. The results clearly highlight the efficiency and the robustness of the approach.

  19. Quantitative Evaluation of Delamination Inside of Composite Materials by ESPI

    International Nuclear Information System (INIS)

    Kim, Koung Suk; Yang, Kwang Young; Kang, Ki Soo; Ji, Chang June

    2004-01-01

    Electronic speckle pattern interferometry (ESPI) for quantitative evaluation of delaminations inside of a composite material plate is described. Delaminations caused by the impact on composite materials are difficult to detect visual inspection and ultrasonic testing due to non-homeogenous structure. This paper proposes the quantitative evaluation technique of the defects made in the composite plates by impact load. Artificial defects are introduced inside of the composite plate for the development of a reliable ESPI inspection technique. Real defects produced by impact tester are inspected and compared with the results of visual inspection which shows a good agreement within 5% error

  20. Delamination detection in reinforced concrete using thermal inertia

    International Nuclear Information System (INIS)

    Del Grande, N K; Durbin, P F.

    1998-01-01

    We investigated the feasibility of thermal inertia mapping for bridge deck inspections. Using pulsed thermal imaging, we heat-stimulated surrogate delaminations in reinforced concrete and asphalt-concrete slabs. Using a dual-band infrared camera system, we measured thermal inertia responses of Styrofoam implants under 5 cm of asphalt, 5 cm of concrete, and 10 cm of asphalt and concrete. We compared thermal maps from solar-heated concrete and asphalt-concrete slabs with thermal inertia maps from flash-heated concrete and asphalt-concrete slabs. Thermal inertia mapping is a tool for visualizing and quantifying subsurface defects. Physically, thermal inertia is a measure of the resistance of the bridge deck to temperature change. Experimentally, it is determined from the inverse slope of the surface temperature versus the inverse square root of time. Mathematically, thermal inertia is the square root of the product of thermal conductivity, density, and heat capacity. Thermal inertia mapping distinguishes delaminated decks which have below-average thermal inertias from normal or shaded decks. Key Words: Pulsed Thermal Imaging, Thermal Inertia, Detection Of Concrete Bridgedeck Delaminations

  1. Free vibration analysis of delaminated composite shells using different shell theories

    International Nuclear Information System (INIS)

    Nanda, Namita; Sahu, S.K.

    2012-01-01

    Free vibration response of laminated composite shells with delamination is presented using the finite element method based on first order shear deformation theory. The shell theory used is the extension of dynamic, shear deformable theory according to the Sanders' first approximation for doubly curved shells, which can be reduced to Love's and Donnell's theories by means of tracers. An eight-noded C 0 continuity, isoparametric quadrilateral element with five degrees of freedom per node is used in the formulation. For modeling the delamination, multipoint constraint algorithm is incorporated in the finite element code. The natural frequencies of the delaminated cylindrical (CYL), spherical (SPH) and hyperbolic paraboloid (HYP) shells are determined by using the above mentioned shell theories, namely Sanders', Love's, and Donnell's. The validity of the present approach is established by comparing the authors' results with those available in the literature. Additional studies on free vibration response of CYL, SPH and HYP shells are conducted to assess the effects of delamination size and number of layers considering all three shell theories. It is shown that shell theories according to Sanders and Love always predict practically identical frequencies. Donnell's theory gives reliable results only for shallow shells. Moreover, the natural frequency is found to be very sensitive to delamination size and number of layers in the shell.

  2. Delamination evaluation of thermal barrier coating on turbine blade owing to isothermal degradation using ultrasonic C-scan image

    International Nuclear Information System (INIS)

    Lee, Ho Girl; Kim, Hak Joon; Song, Sung Jin; Seok, Chang Sung

    2016-01-01

    Thermal barrier coating (TBC) is an essential element consisting of a super-alloy base and ceramic coating designed to achieve long operational time under a high temperature and pressure environment. However, the top coat of TBC can be delaminated at certain temperatures with long operation time. As the delamination of TBC is directly related to the blade damage, the coupling status of the TBC should be assured for reliable operation. Conventional studies of nondestructive evaluation have been made for detecting generation of thermally grown oxide (TGO) or qualitatively evaluating delamination in TBC. In this study, the ultrasonic C-scan method was developed to obtain the damage map inside TBC by estimating the delamination in a quantitative way. All specimens were isothermally degraded at 1,100°C with different time, having different partial delamination area. To detect partial delamination in TBC, the C-scan was performed by a single transducer using pulse-echo method with normal incidence. Partial delamination coefficients of 1 mm to 6 mm were derived by the proportion of the surface reflection signal and flaw signal which were theoretical signals using Rogers-Van Buren and Kim's equations. Using the partial delamination coefficients, the partial delamination maps were obtained. Regardless of the partial delamination coefficient, partial delamination area was increased when degradation time was increased in TBC. In addition, a decrease in partial delamination area in each TBC specimen was observed when the partial delamination coefficient was increased. From the portion of the partial delamination maps, the criterion for delamination was derived

  3. Delamination evaluation of thermal barrier coating on turbine blade owing to isothermal degradation using ultrasonic C-scan image

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ho Girl; Kim, Hak Joon; Song, Sung Jin; Seok, Chang Sung [Dept. of Mechanical Engineering, Sungkyunkwan University, Suwon (Korea, Republic of)

    2016-10-15

    Thermal barrier coating (TBC) is an essential element consisting of a super-alloy base and ceramic coating designed to achieve long operational time under a high temperature and pressure environment. However, the top coat of TBC can be delaminated at certain temperatures with long operation time. As the delamination of TBC is directly related to the blade damage, the coupling status of the TBC should be assured for reliable operation. Conventional studies of nondestructive evaluation have been made for detecting generation of thermally grown oxide (TGO) or qualitatively evaluating delamination in TBC. In this study, the ultrasonic C-scan method was developed to obtain the damage map inside TBC by estimating the delamination in a quantitative way. All specimens were isothermally degraded at 1,100°C with different time, having different partial delamination area. To detect partial delamination in TBC, the C-scan was performed by a single transducer using pulse-echo method with normal incidence. Partial delamination coefficients of 1 mm to 6 mm were derived by the proportion of the surface reflection signal and flaw signal which were theoretical signals using Rogers-Van Buren and Kim's equations. Using the partial delamination coefficients, the partial delamination maps were obtained. Regardless of the partial delamination coefficient, partial delamination area was increased when degradation time was increased in TBC. In addition, a decrease in partial delamination area in each TBC specimen was observed when the partial delamination coefficient was increased. From the portion of the partial delamination maps, the criterion for delamination was derived.

  4. Minimizing and predicting delamination of southern plywood in exterior exposure

    Science.gov (United States)

    Peter Koch

    1967-01-01

    Southern pine plywood is substantially all being manufactured with phenolic glue for exterior use. Because panels must not delaminate in service, a reliable predictor of glueline durability is required. Drawing on the experience of the Douglas-fir plywood industry, southern manufacutrers have adopted as a predictor the percentage of wood failure(% WF) observed in...

  5. Delamination of Compressed Thin Layers at Corners

    DEFF Research Database (Denmark)

    Sørensen, Kim D.; Jensen, Henrik Myhre; Clausen, Johan

    2008-01-01

    An analysis of delamination for a thin elastic layer under compression, attached to a substrate at a corner is carried out. The analysis is performed by combining results from interface fracture mechanics and the theory of thin shells. In contrast with earlier results for delamination on a flat s...... layers, Fracture mechanics, Crack closure, Steady state crack propagation.......An analysis of delamination for a thin elastic layer under compression, attached to a substrate at a corner is carried out. The analysis is performed by combining results from interface fracture mechanics and the theory of thin shells. In contrast with earlier results for delamination on a flat...... results for the fracture mechanical properties have been obtained, and these are applied in a study of the effect of contacting crack faces. Special attention has been given to analyse conditions under which steady state propagation of buckling driven delamination takes place. Keywords: Delamination, Thin...

  6. Delamination tolerance studies in laminated composite panels

    Indian Academy of Sciences (India)

    Abstract. Determination of levels of tolerance in delaminated composite panels is an important issue in composite structures technology. The primary intention is to analyse delaminated composite panels and estimate Strain. Energy Release Rate (SERR) parameters at the delamination front to feed into acceptability criteria.

  7. Thermally induced delamination of multilayers

    DEFF Research Database (Denmark)

    Sørensen, Bent F.; Sarraute, S.; Jørgensen, O.

    1998-01-01

    Steady-state delamination of multilayered structures, caused by stresses arising during processing due to thermal expansion mismatch, is analyzed by a fracture mechanics model based on laminate theory. It is found that inserting just a few interlayers with intermediate thermal expansion coefficie...... coefficients may be an effective way of reducing the delamination energy release rate. Uneven layer thickness and increasing elastic mismatch are shown to raise the energy release rate. Experimental work confirms important trends of the model.......Steady-state delamination of multilayered structures, caused by stresses arising during processing due to thermal expansion mismatch, is analyzed by a fracture mechanics model based on laminate theory. It is found that inserting just a few interlayers with intermediate thermal expansion...

  8. Incorporation of plasma-functionalized carbon nanostructures in composite laminates for interlaminar reinforcement and delamination crack monitoring

    Science.gov (United States)

    Kravchenko, O. G.; Pedrazzoli, D.; Kovtun, D.; Qian, X.; Manas-Zloczower, I.

    2018-01-01

    A new approach employing carbon nanostructure (CNS) buckypapers (BP) was used to prepare glass fiber/epoxy composite materials with enhanced resistance to delamination along with damage monitoring capability. The CNS-BP was subjected to plasma treatment to improve its wettability by epoxy and to promote stronger interfacial bonding. An increase up to 20% in interlaminar fracture toughness in mode I and mode II was observed in composite laminates incorporating CNS BP. Morphological analysis of the fracture surfaces indicated that failure in the conductive CNS layer provided a more effective energy dissipation mechanism, resulting in interlaminar fracture toughness increase. Moreover, fracture of the conductive CNS layer enabled damage monitoring of the composite by electrical resistance measurements upon delamination. The proposed approach provides multifunctional ply interphases, allowing to couple damage monitoring with interlaminar reinforcement of composite laminates.

  9. Buckling-driven delamination growth in composite laminates: Guidelines for assessing the threat posed by interlaminar matrix delamination

    DEFF Research Database (Denmark)

    Bhushan, Karihaloo; Stang, Henrik

    2008-01-01

    This paper is concerned with development of a simple procedure to assess the threat posed by interlaminar matrix delaminations to the integrity of composite laminates when they are situated in a compressive stress field. Depending upon the size of the delamination, its location below the surface...

  10. Delamination Detection of Reinforced Concrete Decks Using Modal Identification

    Directory of Open Access Journals (Sweden)

    Shutao Xing

    2012-01-01

    Full Text Available This study addressed delamination detection of concrete slabs by analyzing global dynamic responses of structures. Both numerical and experimental studies are presented. In the numerical examples, delaminations with different sizes and locations were introduced into a concrete slab; the effects of presence, sizes, and locations of delaminations on the modal frequencies and mode shapes of the concrete slab under various support conditions were studied. In the experimental study, four concrete deck specimens with different delamination sizes were constructed, and experimental tests were conducted. Traditional peak-picking, frequency domain decomposition, and stochastic subspace identification methods were applied to the modal identification from dynamic response measurements. The modal parameters identified by these three methods correlated well. The changes in modal frequencies, damping ratios, and mode shapes that were extracted from the dynamic measurements were investigated and correlated to the actual delaminations and can indicate presence and severity of delamination. Finite element (FE models of reinforced concrete decks with different delamination sizes and locations were established. The modal parameters computed from the FE models were compared to those obtained from the laboratory specimens, and the FE models were validated. The delamination detection approach was proved to be effective for concrete decks on beams.

  11. Numerical simulations of the mantle lithosphere delamination

    Science.gov (United States)

    Morency, C.; Doin, M.-P.

    2004-03-01

    Sudden uplift, extension, and increased igneous activity are often explained by rapid mechanical thinning of the lithospheric mantle. Two main thinning mechanisms have been proposed, convective removal of a thickened lithospheric root and delamination of the mantle lithosphere along the Moho. In the latter case, the whole mantle lithosphere peels away from the crust by the propagation of a localized shear zone and sinks into the mantle. To study this mechanism, we perform two-dimensional (2-D) numerical simulations of convection using a viscoplastic rheology with an effective viscosity depending strongly on temperature, depth, composition (crust/mantle), and stress. The simulations develop in four steps. (1) We first obtain "classical" sublithospheric convection for a long time period (˜300 Myr), yielding a slightly heterogeneous lithospheric temperature structure. (2) At some time, in some simulations, a strong thinning of the mantle occurs progressively in a small area (˜100 km wide). This process puts the asthenosphere in direct contact with the lower crust. (3) Large pieces of mantle lithosphere then quickly sink into the mantle by the horizontal propagation of a detachment level away from the "asthenospheric conduit" or by progressive erosion on the flanks of the delaminated area. (4) Delamination pauses or stops when the lithospheric mantle part detaches or when small-scale convection on the flanks of the delaminated area is counterbalanced by heat diffusion. We determine the parameters (crustal thicknesses, activation energies, and friction coefficients) leading to delamination initiation (step 2). We find that delamination initiates where the Moho temperature is the highest, as soon as the crust and mantle viscosities are sufficiently low. Delamination should occur on Earth when the Moho temperature exceeds ˜800°C. This condition can be reached by thermal relaxation in a thickened crust in orogenic setting or by corner flow lithospheric erosion in the

  12. THE EFFECT OF SUPPORT PLATE ON DRILLING-INDUCED DELAMINATION

    Directory of Open Access Journals (Sweden)

    Navid Zarif Karimi

    2016-02-01

    Full Text Available Delamination is considered as a major problem in drilling of composite materials, which degrades the mechanical properties of these materials. The thrust force exerted by the drill is considered as the major cause of delamination; and one practical approach to reduce delamination is to use a back-up plate under the specimen. In this paper, the effect of exit support plate on delamination in twist drilling of glass fiber reinforced composites is studied. Firstly, two analytical models based on linear fracture mechanics and elastic bending theory of plates are described to find critical thrust forces at the beginning of crack growth for drilling with and without back-up plate. Secondly, two series of experiments are carried out on glass fiber reinforced composites to determine quantitatively the effect of drilling parameters on the amount of delamination. Experimental findings verify a large reduction in the amount of delaminated area when a back-up plate is placed under the specimen.

  13. Using glass-graded zirconia to increase delamination growth resistance in porcelain/zirconia dental structures.

    Science.gov (United States)

    Chai, Herzl; Mieleszko, Adam J; Chu, Stephen J; Zhang, Yu

    2018-01-01

    Porcelain fused to zirconia (PFZ) restorations are widely used in prosthetic dentistry. However, their tendency to delaminate along the P/Z interface remains a practical problem so that assessing and improving the interfacial strength are important design aspects. This work examines the effect of modifying the zirconia veneering surface with an in-house felspathic glass on the interfacial fracture resistance of fused P/Z. Three material systems are studied: porcelain fused to zirconia (control) and porcelain fused to glass-graded zirconia with and without the presence of a glass interlayer. The specimens were loaded in a four-point-bend fixture with the porcelain veneer in tension. The evolution of damage is followed with the aid of a video camera. The interfacial fracture energy G C was determined with the aid of a FEA, taking into account the stress shielding effects due to the presence of adjacent channel cracks. Similarly to a previous study on PFZ specimens, the fracture sequence consisted of unstable growth of channel cracks in the veneer followed by stable cracking along the P/Z interface. However, the value of GC for the graded zirconia was approximately 3 times that of the control zirconia, which is due to the good adhesion between porcelain and the glass network structure on the zirconia surface. Combined with its improved bonding to resin-based cements, increased resistance to surface damage and good esthetic quality, graded zirconia emerges as a viable material concept for dental restorations. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  14. Edge Delamination of Monolayer Transition Metal Dichalcogenides.

    Science.gov (United States)

    Ly, Thuc Hue; Yun, Seok Joon; Thi, Quoc Huy; Zhao, Jiong

    2017-07-25

    Delamination of thin films from the supportive substrates is a critical issue within the thin film industry. The emergent two-dimensional, atomic layered materials, including transition metal dichalcogenides, are highly flexible; thus buckles and wrinkles can be easily generated and play vital roles in the corresponding physical properties. Here we introduce one kind of patterned buckling behavior caused by the delamination from a substrate initiated at the edges of the chemical vapor deposition synthesized monolayer transition metal dichalcogenides, led by thermal expansion mismatch. The atomic force microscopy and optical characterizations clearly showed the puckered structures associated with the strain, whereas the transmission electron microscopy revealed the special sawtooth-shaped edges, which break the geometrical symmetry for the buckling behavior of hexagonal samples. The condition of the edge delamination is in accordance with the fracture behavior of thin film interfaces. This edge delamination and buckling process is universal for most ultrathin two-dimensional materials, which requires more attention in various future applications.

  15. Delamination of Compressed Thin Layers at Corners

    DEFF Research Database (Denmark)

    Sørensen, Kim D.; Jensen, Henrik Myhre; Clausen, Johan

    2008-01-01

    An analysis of delamination for a thin elastic layer under compression, attached to a substrate at a corner is carried out. The analysis is performed by combining results from interface fracture mechanics and the theory of thin shells. In contrast with earlier results for delamination on a flat...

  16. Experimental evaluation of coating delamination in vinyl coated metal forming

    International Nuclear Information System (INIS)

    Son, Young Ki; Lee, Chan Joo; Kim, Byung Min; Lee, Jung Min; Byoen, Sang Doek; Lee, Soen Bong

    2012-01-01

    In this paper, a new evaluation and prediction method for coating delamination during sheet metal forming is presented. On the basis of the forming limit diagram (FLD), the current study evaluates the delamination of PET coating by using a cross cut specimen, dome test, and rectangular cup drawing test. Dome test specimens were subjected to biaxial, plane strain, and uniaxial deformation modes. Rectangular cup drawing test specimens were subjected to the deep drawing deformation mode, and compression deformation mode. A vinyl coated metal (VCM) sheet consists of three layers of polymer on the sheet metals: a protective film, a PET layer and a PVC layer. The areas with coating delamination were identified, and the results of the evaluation were plotted according to major and minor strain values, depicting coating delamination. The constructed delamination limit diagram (DLD) can be used to determine the forming limit of VCM during the complex press forming process. ARGUS (GOM) was employed to identify the strain value and deformation mode of the delaminated surface after the press forming. After identifying the areas of delamination, the DLD of the PET coating can be constructed in a format similar to that of the FLD. The forming limit of the VCM sheet can be evaluated using the superimposition of the delamination limit strain of the coating onto the FLD of VCM sheet. The experimental results showed that the proposed test method will support the sheet metal forming process design for VCM sheets. The assessment method presented in this study can be used to determine the delamination limit strain under plastic deformation of other polymer coated metals. The experimental results suggested that the proposed testing method is effective in evaluating delamination for specific applications

  17. Experimental evaluation of coating delamination in vinyl coated metal forming

    Energy Technology Data Exchange (ETDEWEB)

    Son, Young Ki; Lee, Chan Joo; Kim, Byung Min [Pusan National Univ., Busan (Korea, Republic of); Lee, Jung Min [Korea Institute of Industrial Technology, Busan (Korea, Republic of); Byoen, Sang Doek [HA Digital Engineering Gr., Seongsan Gu (Korea, Republic of); Lee, Soen Bong [Keimyung Univ., Daegu (Korea, Republic of)

    2012-10-15

    In this paper, a new evaluation and prediction method for coating delamination during sheet metal forming is presented. On the basis of the forming limit diagram (FLD), the current study evaluates the delamination of PET coating by using a cross cut specimen, dome test, and rectangular cup drawing test. Dome test specimens were subjected to biaxial, plane strain, and uniaxial deformation modes. Rectangular cup drawing test specimens were subjected to the deep drawing deformation mode, and compression deformation mode. A vinyl coated metal (VCM) sheet consists of three layers of polymer on the sheet metals: a protective film, a PET layer and a PVC layer. The areas with coating delamination were identified, and the results of the evaluation were plotted according to major and minor strain values, depicting coating delamination. The constructed delamination limit diagram (DLD) can be used to determine the forming limit of VCM during the complex press forming process. ARGUS (GOM) was employed to identify the strain value and deformation mode of the delaminated surface after the press forming. After identifying the areas of delamination, the DLD of the PET coating can be constructed in a format similar to that of the FLD. The forming limit of the VCM sheet can be evaluated using the superimposition of the delamination limit strain of the coating onto the FLD of VCM sheet. The experimental results showed that the proposed test method will support the sheet metal forming process design for VCM sheets. The assessment method presented in this study can be used to determine the delamination limit strain under plastic deformation of other polymer coated metals. The experimental results suggested that the proposed testing method is effective in evaluating delamination for specific applications.

  18. Scattering of guided waves at delaminations in composite plates.

    Science.gov (United States)

    Murat, Bibi I S; Khalili, Pouyan; Fromme, Paul

    2016-06-01

    Carbon fiber laminate composites are increasingly employed for aerospace structures as they offer advantages, such as a good strength to weight ratio. However, impact during the operation and servicing of the aircraft can lead to barely visible and difficult to detect damage. Depending on the severity of the impact, fiber and matrix breakage or delaminations can occur, reducing the load carrying capacity of the structure. Efficient nondestructive testing and structural health monitoring of composite panels can be achieved using guided ultrasonic waves propagating along the structure. The scattering of the A0 Lamb wave mode at delaminations was investigated using a full three-dimensional (3D) finite element (FE) analysis. The influence of the delamination geometry (size and depth) was systematically evaluated. In addition to the depth dependency, a significant influence of the delamination width due to sideways reflection of the guided waves within the delamination area was found. Mixed-mode defects were simulated using a combined model of delamination with localized material degradation. The guided wave scattering at cross-ply composite plates with impact damage was measured experimentally using a non-contact laser interferometer. Good agreement between experiments and FE predictions using the mixed-mode model for an approximation of the impact damage was found.

  19. Failure analysis of multiple delaminated composite plates due

    Indian Academy of Sciences (India)

    The present work aims at the first ply failure analysis of laminated composite plates with arbitrarily located multiple delaminations subjected to transverse static load as well as impact. The theoretical formulation is based on a simple multiple delamination model. Conventional first order shear deformation is assumed using ...

  20. Numerical investigation of the effect of delaminations on fracture characteristics of glare

    Science.gov (United States)

    Bhat, Sunil; Narayanan, S.

    2013-10-01

    A finite element examination of the effect of delaminations on fracture characteristics of fibre metal laminate (Glare), by comparing energy release rates of normal cracks in laminates with and without delaminations, is presented in the paper. Glare comprising thin cracked 2024-T3 aerospace aluminum alloy layers alternately bonded with E-glass fibre based composite prepregs is considered for the analysis. Delaminations are modeled with interface cohesive elements. Energy release rates of normal cracks in laminates with delaminations are found to be higher than those in the laminates without delaminations.

  1. Floating Carpets and the Delamination of Elastic Sheets

    KAUST Repository

    Wagner, Till J. W.

    2011-07-22

    We investigate the deformation of a thin elastic sheet floating on a liquid surface and subject to a uniaxial compression. We show that at a critical compression the sheet delaminates from the liquid over a finite region forming a delamination "blister." This blistering regime adds to the wrinkling and localized folding regimes that have been studied previously. The transition from wrinkled to blistered states occurs when delamination becomes energetically favorable compared with wrinkling. We determine the initial blister size and the evolution of blister size with continuing compression before verifying our theoretical results with experiments at a macroscopic scale. © 2011 American Physical Society.

  2. Optimum Electrode Configurations for Two-Probe, Four-Probe and Multi-Probe Schemes in Electrical Resistance Tomography for Delamination Identification in Carbon Fiber Reinforced Composites

    Directory of Open Access Journals (Sweden)

    Luis Waldo Escalona-Galvis

    2018-04-01

    Full Text Available Internal damage in Carbon Fiber Reinforced Polymer (CFRP composites modifies the internal electrical conductivity of the composite material. Electrical Resistance Tomography (ERT is a non-destructive evaluation (NDE technique that determines the extent of damage based on electrical conductivity changes. Implementation of ERT for damage identification in CFRP composites requires the optimal selection of the sensing sites for accurate results. This selection depends on the measuring scheme used. The present work uses an effective independence (EI measure for selecting the minimum set of measurements for ERT damage identification using three measuring schemes: two-probe, four-probe and multi-probe. The electrical potential field in two CFRP laminate layups with 14 electrodes is calculated using finite element analyses (FEA for a set of specified delamination damage cases. The measuring schemes consider the cases of 14 electrodes distributed on both sides and seven electrodes on only one side of the laminate for each layup. The effectiveness of EI reduction is demonstrated by comparing the inverse identification results of delamination cases for the full and the reduced sets using the measuring schemes and electrode sets. This work shows that the EI measure optimally reduces electrode and electrode combinations in ERT based damage identification for different measuring schemes.

  3. Numerical Investigation of Delamination in Drilling of Carbon Fiber Reinforced Polymer Composites

    Science.gov (United States)

    Tang, Wenliang; Chen, Yan; Yang, Haojun; Wang, Hua; Yao, Qiwei

    2018-03-01

    Drilling of carbon fiber reinforced polymer (CFRP) is a challenging task in modern manufacturing sector and machining induced delamination is one of the major problems affecting assembly precision. In this work, a new three-dimensional (3D) finite element model is developed to study the chip formation and entrance delamination in drilling of CFRP composites on the microscopic level. Fiber phase, matrix phase and equivalent homogeneous phase in the multi-phase model have different constitutive behaviors, respectively. A comparative drilling test, in which the cement carbide drill and unidirectional CFRP laminate are employed, is conducted to validate the proposedmodel in terms of the delamination and the similar changing trend is obtained. Microscopic mechanism of entrance delamination together with the chip formation process at four special fiber cutting angles (0°, 45°, 90° and 135°) is investigated. Moreover, the peeling force is also predicted. The results show that the delamination occurrence and the chip formation are both strongly dependent on the fiber cutting angle. The length of entrance delamination rises with increasing fiber cutting angles. Negligible delamination at 0° is attributed to the compression by the minor flank face. For 45° and 90°, the delamination resulted from the mode III fracture. At 135°, serious delamination which is driven by the mode I and III fractures is more inclined to occur and the peeling force reaches its maximum. Such numerical models can help understand the mechanism of hole entrance delamination further and provide guidance for the damage-free drilling of CFRP.

  4. Study of multilayer packaging delamination mechanisms using different surface analysis techniques

    Energy Technology Data Exchange (ETDEWEB)

    Garrido-Lopez, Alvaro [Department of Chemistry, University of La Rioja, C/Madre de Dios 51, E-26006 Logrono, La Rioja (Spain); Tena, Maria Teresa, E-mail: maria-teresa.tena@unirioja.es [Department of Chemistry, University of La Rioja, C/Madre de Dios 51, E-26006 Logrono, La Rioja (Spain)

    2010-04-01

    Multilayer packaging, consisting of different layers joined by using an adhesive or an extrusion process, is widely used to promote different products, such as food, cosmetics, etc. The main disadvantage in using this form of packaging is the delamination process. In this work, different surface techniques (X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectroscopy and attenuated total reflection Fourier transform infrared spectroscopy) are used to analyse the delaminated surfaces in order to study the mechanisms that cause delamination of multilayer packaging. According to our results, the reaction of migrated molecules with adhesive-aluminium bonds is the main cause of the chemical delamination process. In contrast, the delamination of extruded materials would seem to be caused by the breaking of Van der Waals bonds.

  5. Repair of prestressed concrete cylinder with localized delamination

    International Nuclear Information System (INIS)

    Wang, Shen; Munshi, Javeed A.

    2015-01-01

    For prestressed concrete cylindrical structures such as nuclear containments, tanks and silos, the curvature effect of the tendons introduces radial tensile stresses in the concrete shell which are generally neglected in the design of such structures. For example, many prestressed concrete nuclear containments in US, especially those which were not designed following radial reinforcement requirement of ACI-359, are reinforced only in the circumferential (hoop) and meridional (vertical) directions but not in the radial direction. This leaves these structures vulnerable to potential laminar cracking and delamination, especially during post-tensioning and/or detensioning process. Should delamination occur, the structure needs to be repaired by either replacing cracked concrete or by “pinning” the delaminated concrete layers together by post-installed anchors. The latter option of post-installed anchors is less invasive from construction stand point and generally suitable for repairing small or localized delamination only. A comprehensive study is undertaken to explore various aspects and design consideration of post-installed anchors for prestressed concrete cylinders. The radial tension demand is first established by combining a mechanical based model with a detailed finite element analysis. With such design demand for post-installed anchors established, the next step aims at developing the tightness requirement of existing delamination cracks for effective use of post-installed anchors. A comprehensive literature search and evaluation is carried out for shear transfer capacity across cracks of various widths. The findings are used to develop specific recommendations for acceptable crack widths to ensure adequate in-plane shear transfer capacity for various design load conditions. A design process for post-installed anchors is proposed for repairing a delaminated prestressed concrete cylindrical structure at the end of the paper, supplemented by an illustrative

  6. Repair of prestressed concrete cylinder with localized delamination

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shen, E-mail: swang@bechtel.com; Munshi, Javeed A., E-mail: jamunshi@bechtel.com

    2015-12-15

    For prestressed concrete cylindrical structures such as nuclear containments, tanks and silos, the curvature effect of the tendons introduces radial tensile stresses in the concrete shell which are generally neglected in the design of such structures. For example, many prestressed concrete nuclear containments in US, especially those which were not designed following radial reinforcement requirement of ACI-359, are reinforced only in the circumferential (hoop) and meridional (vertical) directions but not in the radial direction. This leaves these structures vulnerable to potential laminar cracking and delamination, especially during post-tensioning and/or detensioning process. Should delamination occur, the structure needs to be repaired by either replacing cracked concrete or by “pinning” the delaminated concrete layers together by post-installed anchors. The latter option of post-installed anchors is less invasive from construction stand point and generally suitable for repairing small or localized delamination only. A comprehensive study is undertaken to explore various aspects and design consideration of post-installed anchors for prestressed concrete cylinders. The radial tension demand is first established by combining a mechanical based model with a detailed finite element analysis. With such design demand for post-installed anchors established, the next step aims at developing the tightness requirement of existing delamination cracks for effective use of post-installed anchors. A comprehensive literature search and evaluation is carried out for shear transfer capacity across cracks of various widths. The findings are used to develop specific recommendations for acceptable crack widths to ensure adequate in-plane shear transfer capacity for various design load conditions. A design process for post-installed anchors is proposed for repairing a delaminated prestressed concrete cylindrical structure at the end of the paper, supplemented by an illustrative

  7. Critical current survival in the YBCO superconducting layer of a delaminated coated conductor

    Science.gov (United States)

    Feng, Feng; Fu, Qishu; Qu, Timing; Mu, Hui; Gu, Chen; Yue, Yubin; Wang, Linli; Yang, Zhirong; Han, Zhenghe; Feng, Pingfa

    2018-04-01

    A high-temperature superconducting coated conductor can be practically applied in electric equipment due to its favorable mechanical properties and critical current (I c) performance. However, the coated conductor can easily delaminate because of its poor stress tolerance along the thickness direction. It would be interesting to investigate whether the I c of the delaminated YBa2Cu3O7-δ (YBCO) layer can be preserved. In this study, coated conductor samples manufactured through the metal organic deposition route were delaminated by liquid nitrogen immersion. Delaminated samples, including the YBCO layer and silver stabilizer, were obtained. Delamination occurred inside the YBCO layer and near the YBCO-CeO2 interface, as suggested by the results of scanning electron microscopy (SEM) and x-ray diffraction. A scanning Hall probe system was employed to measure the I c distribution of the original sample and the delaminated sample. It was found that approximately 50% of the I c can be preserved after delamination, which was verified by I c measurements using the four-probe method. Dense and crack-free morphologies of the delaminated surfaces were observed by SEM, which accounts for the I c survival of the delaminated YBCO layer. The potential application of the delaminated sample in superconducting joints was discussed based on the oxygen diffusion estimation.

  8. Combined effect of matrix cracking and stress-free edge on delamination

    Science.gov (United States)

    Salpekar, S. A.; Obrien, T. K.

    1990-01-01

    The effect of the stress-free edge on the growth of local delaminations initiating from a matrix crack in (0 sub 2/90 sub 4) sub s and (+ or - 45.90 sub 4) sub s glass epoxy laminates is investigated using 3-D finite element analysis. The presence of high interlaminar normal stresses at the intersection (corner) of the matrix crack with the stress-free edge, suggests that a mode I delamination may initiate at the corners. The strain energy release rates (G) were calculated by modeling a uniform through-width delamination and two inclined delaminations at 10.6 deg and 45 deg to the matrix crack. All components of G have high values near the free edges. The mode I component of G is high at small delamination length and becomes zero for a delamination length of one-ply thickness. The total G values near the free edge agreed well with previously derived closed form solution. The quasi-3D solutions agreed well with the 3-D interior solutions.

  9. MR imaging of delamination tears of the rotator cuff tendons

    International Nuclear Information System (INIS)

    Walz, Daniel M.; Chen, Steven; Miller, Theodore T.; Hofman, Josh

    2007-01-01

    The objective was to describe the imaging appearances and location of delamination tears of the rotator cuff tendons on non-contrast conventional MR imaging. This study was reviewed and approved by our Institutional Review Board. The reports of 548 consecutive MR examinations of the shoulder were reviewed, looking for mention or description of delamination tears of the rotator cuff. The images of the identified cases were then reviewed by two radiologists to confirm the findings. Correlation with surgical and arthroscopic information was then performed. Delamination tears were defined as horizontal retraction of either the bursal or articular surface of the tendon, manifest as thickening of the torn retracted edge, and/or interstitial splitting of the tendon, manifest as fluid-like high signal intensity on fat-suppressed T2-weighted oblique coronal images. Fourteen cases of delamination tears were identified in 13 patients. Ten of the cases involved the supraspinatus tendon, all with articular surface involvement. Nine of these supraspinatus cases were isolated tears and one occurred as part of a full thickness tear. All 10 of these supraspinatus cases showed medial retraction of the articular surface of the tendon, with thickening of the retracted edge, and 5 of the 10 had a demonstrable horizontal cleft in the interstitium. Four cases involved the subscapularis tendon, with articular surface disruption in three and pure interstitial delamination in one. Medial subluxation of the tendon of the long head of the biceps was present in all four cases. No delamination tears occurred on the bursal surface. Only three of the 14 shoulders underwent surgical repair with one confirmation of supraspinatus delamination, one confirmation of a subscapularis tear that had become a full thickness tear 10 months after initial imaging and another interstitial subscapularis delamination that was not identified arthroscopically. Delamination tears occur most often in the

  10. MR imaging of delamination tears of the rotator cuff tendons

    Energy Technology Data Exchange (ETDEWEB)

    Walz, Daniel M.; Chen, Steven [North Shore University Hospital, Department of Radiology, Manhasset, NY (United States); Miller, Theodore T. [Hospital for Special Surgery, Department of Radiology and Imaging, New York, NY (United States); Hofman, Josh [Long Island Jewish Medical Center, New Hyde Park, NY (United States)

    2007-05-15

    The objective was to describe the imaging appearances and location of delamination tears of the rotator cuff tendons on non-contrast conventional MR imaging. This study was reviewed and approved by our Institutional Review Board. The reports of 548 consecutive MR examinations of the shoulder were reviewed, looking for mention or description of delamination tears of the rotator cuff. The images of the identified cases were then reviewed by two radiologists to confirm the findings. Correlation with surgical and arthroscopic information was then performed. Delamination tears were defined as horizontal retraction of either the bursal or articular surface of the tendon, manifest as thickening of the torn retracted edge, and/or interstitial splitting of the tendon, manifest as fluid-like high signal intensity on fat-suppressed T2-weighted oblique coronal images. Fourteen cases of delamination tears were identified in 13 patients. Ten of the cases involved the supraspinatus tendon, all with articular surface involvement. Nine of these supraspinatus cases were isolated tears and one occurred as part of a full thickness tear. All 10 of these supraspinatus cases showed medial retraction of the articular surface of the tendon, with thickening of the retracted edge, and 5 of the 10 had a demonstrable horizontal cleft in the interstitium. Four cases involved the subscapularis tendon, with articular surface disruption in three and pure interstitial delamination in one. Medial subluxation of the tendon of the long head of the biceps was present in all four cases. No delamination tears occurred on the bursal surface. Only three of the 14 shoulders underwent surgical repair with one confirmation of supraspinatus delamination, one confirmation of a subscapularis tear that had become a full thickness tear 10 months after initial imaging and another interstitial subscapularis delamination that was not identified arthroscopically. Delamination tears occur most often in the

  11. The Effect of Substrate Topography on Coating Cathodic Delamination

    DEFF Research Database (Denmark)

    Erik Weinell, Claus; Sørensen, Per A.; Kiil, Søren

    2011-01-01

    This article describes the effect of steel substrate topography on coating cathodic delamination. The study showed that the surface preparation can be used to control and minimize the rate of cathodic delamination. The coating should have maximum wetting properties so that substrates with high...

  12. Failure analysis of multiple delaminated composite plates due to ...

    Indian Academy of Sciences (India)

    Unknown

    plates are assumed to contain both single and multiple delaminations. For the case of impact, ... delamination on the first ply failure of the laminate is scarce. ..... 1 in the bottom layer, it was of the opposite sign for the top layer. The plots for ...

  13. Microscopic mechanisms of graphene electrolytic delamination from metal substrates

    International Nuclear Information System (INIS)

    Fisichella, G.; Di Franco, S.; Roccaforte, F.; Giannazzo, F.; Ravesi, S.

    2014-01-01

    In this paper, hydrogen bubbling delamination of graphene (Gr) from copper using a strong electrolyte (KOH) water solution was performed, focusing on the effect of the KOH concentration (C KOH ) on the Gr delamination rate. A factor of ∼10 decrease in the time required for the complete Gr delamination from Cu cathodes with the same geometry was found increasing C KOH from ∼0.05 M to ∼0.60 M. After transfer of the separated Gr membranes to SiO 2 substrates by a highly reproducible thermo-compression printing method, an accurate atomic force microscopy investigation of the changes in Gr morphology as a function of C KOH was performed. Supported by these analyses, a microscopic model of the delamination process has been proposed, where a key role is played by graphene wrinkles acting as nucleation sites for H 2 bubbles at the cathode perimeter. With this approach, the H 2 supersaturation generated at the electrode for different electrolyte concentrations was estimated and the inverse dependence of t d on C KOH was quantitatively explained. Although developed in the case of Cu, this analysis is generally valid and can be applied to describe the electrolytic delamination of graphene from several metal substrates.

  14. Photovoltaic module reliability improvement through application testing and failure analysis

    Science.gov (United States)

    Dumas, L. N.; Shumka, A.

    1982-01-01

    During the first four years of the U.S. Department of Energy (DOE) National Photovoltatic Program, the Jet Propulsion Laboratory Low-Cost Solar Array (LSA) Project purchased about 400 kW of photovoltaic modules for test and experiments. In order to identify, report, and analyze test and operational problems with the Block Procurement modules, a problem/failure reporting and analysis system was implemented by the LSA Project with the main purpose of providing manufacturers with feedback from test and field experience needed for the improvement of product performance and reliability. A description of the more significant types of failures is presented, taking into account interconnects, cracked cells, dielectric breakdown, delamination, and corrosion. Current design practices and reliability evaluations are also discussed. The conducted evaluation indicates that current module designs incorporate damage-resistant and fault-tolerant features which address field failure mechanisms observed to date.

  15. Characterization of exfoliated/delamination kaolinite

    International Nuclear Information System (INIS)

    Sun, Dewen; Li, Bin; Li, Yanfeng; Yu, Cui; Zhang, Bo; Fei, Huafeng

    2011-01-01

    A novel and facile approach for the preparation of exfoliated/delamination kaolinite was reported in this study. Kaolinite was mechanochemically activated by grinding with dimethylsulfoxide in a globe mill for different periods of time, and then the activated samples were treated for several hours at 120 o C to obtain the precursors of kaolinite. The resulting materials were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The experimental data indicated that the clay layers were well exfoliated/delamination under mechanochemical effect in a significantly short intercalation time. The expansion of the basal spacing (d 001 ) of raw kaolinite by 0.40 nm pointed out that the hydrogen bonds between adjacent kaolinite layers were partially broken as a result of the intercalation with dimethylsulfoxide.

  16. Mechanistic Study of Delamination Fracture in Al-Li Alloy C458 (2099)

    Science.gov (United States)

    Tayon, W. A.; Crooks, R. E.; Domack, M. S.; Wagner, J. A.; Beaudoin, A. J.; McDonald, R. J.

    2009-01-01

    Delamination fracture has limited the use of lightweight Al-Li alloys. In the present study, electron backscattered diffraction (EBSD) methods were used to characterize crack paths in Al-Li alloy C458 (2099). Secondary delamination cracks in fracture toughness samples showed a pronounced tendency for fracture between grain variants of the same deformation texture component. These results were analyzed by EBSD mapping methods and simulated with finite element analyses. Simulation procedures include a description of material anisotropy, local grain orientations, and fracture utilizing crystal plasticity and cohesive zone elements. Taylor factors computed for each grain orientation subjected to normal and shear stresses indicated that grain pairs with the largest Taylor factor differences were adjacent to boundaries that failed by delamination. Examination of matching delamination fracture surface pairs revealed pronounced slip bands in only one of the grains bordering the delamination. These results, along with EBSD studies, plasticity simulations, and Auger electron spectroscopy observations support a hypothesis that delamination fracture occurs due to poor slip accommodation along boundaries between grains with greatly differing plastic response.

  17. Delamination behaviour of GdBCO coated conductor tapes under transverse tension

    International Nuclear Information System (INIS)

    Gorospe, A.; Nisay, A.; Dizon, J.R.; Shin, H.S.

    2013-01-01

    Highlights: •Installation of a test frame which gives precisely aligned transverse load. •Investigation of I c degradation behaviour depending on the type of sample delamination. •Inhomogeneity of the CC tapes caused large variation on delamination strength. •SEM and EDS analysis of delamination sites under transverse loading. -- Abstract: The electromechanical property behaviour of 2G coated conductor (CC) tapes fabricated by multi-layer deposition process both in the in-plane and transverse direction should be understood. The CC tapes are used in the fabrication of epoxy resin-impregnated coils. In such case, the Lorentz force due to the high magnetic field applied as well as the thermal stress due to the difference in coefficient of thermal expansion (CTE) among constituent layers during cooling to cryogenic temperature will induce transversely applied load to the surface of CC tapes in coils. Hence, the CC tape should have a good mechanical property in the transverse direction in order to maintain its superior performance under magnetic field. In this study, a test frame which gives precisely aligned transverse load was devised. Using the fixture, the delamination behaviours including the delamination strength of the GdBCO CC tapes under transverse tensile loading were investigated. Large variation on the delamination strength of the CC tapes was recorded and might have resulted from the slit edge effect and the inhomogeneity of the CC tapes. The I c degradation behaviour under transverse load was related to the location where delamination occurred in the sample

  18. Influence of substrate topography on cathodic delamination of anticorrosive coatings

    DEFF Research Database (Denmark)

    Sørensen, Per Aggerholm; Kiil, Søren; Dam-Johansen, Kim

    2009-01-01

    and thereby the substrate topography, whereas the coating thickness had little influence. The presence of a significant potential gradient between the anode and the cathode and the dependency of the delamination rate on the tortuosity of the steel surface suggests that cathodic delamination is controlled...

  19. Delamination in surface plies of graphite/epoxy caused by the edge trimming process

    Science.gov (United States)

    Colligan, K.; Ramulu, M.

    Delamination in surface plies of graphite/epoxy laminates caused by edge trimming using polycrystalline diamond (PCD) and carbide cutters is investigated. The effect of several machining variables on formation of delaminations in the surface plies of a graphite fiber reinforced composite material is presented. Machining tests were performed to assess the impact of cutter geometry, feedrate, rotation direction, and graphite fiber orientation. Three typical delamination modes were observed and documented. Feedrate was found to have a significant effect on surface ply delamination in graphite/epoxy composite materials.

  20. Hygrothermal influence on delamination behavior of graphite/epoxy laminates

    Science.gov (United States)

    Garg, A.; Ishai, O.

    1985-01-01

    The hygrothermal effect on the fracture behavior of graphite-epoxy laminates was investigated to develop a methodology for damage tolerance predictions in advanced composite materials. Several T300/934 laminates were tested using a number of specimen configurations to evaluate the effects of temperature and humidity on delamination fracture toughness under mode 1 and mode 2 loading. It is indicated that moisture has a slightly beneficial influence on fracture toughness or critical strain energy release rate during mode 1 delamination, but has a slightly deleterious effect on mode 2 delamination, and mode 1 transverse cracking. The failed specimens are examined by SEM and topographical differences due to fracture modes are identified. It is concluded that the effect of moisture on fracture topography can not be distinguished.

  1. Reliable processing of graphene using metal etchmasks

    Directory of Open Access Journals (Sweden)

    Peltekis Nikos

    2011-01-01

    Full Text Available Abstract Graphene exhibits exciting properties which make it an appealing candidate for use in electronic devices. Reliable processes for device fabrication are crucial prerequisites for this. We developed a large area of CVD synthesis and transfer of graphene films. With patterning of these graphene layers using standard photoresist masks, we are able to produce arrays of gated graphene devices with four point contacts. The etching and lift off process poses problems because of delamination and contamination due to polymer residues when using standard resists. We introduce a metal etch mask which minimises these problems. The high quality of graphene is shown by Raman and XPS spectroscopy as well as electrical measurements. The process is of high value for applications, as it improves the processability of graphene using high-throughput lithography and etching techniques.

  2. Delamination behaviour in differently copper laminated REBCO coated conductor tapes under transverse loading

    Energy Technology Data Exchange (ETDEWEB)

    Gorospe, Alking [Department of Mechanical Design Engineering, Andong National University, 1375 Kyungdong-Ro, Andong 760-749 (Korea, Republic of); Department of Engineering, Aurora State College of Technology, Baler Aurora 3200 (Philippines); Nisay, Arman [Department of Mechanical Design Engineering, Andong National University, 1375 Kyungdong-Ro, Andong 760-749 (Korea, Republic of); Shin, Hyung-Seop, E-mail: hsshin@andong.ac.kr [Department of Mechanical Design Engineering, Andong National University, 1375 Kyungdong-Ro, Andong 760-749 (Korea, Republic of)

    2014-09-15

    Highlights: • I{sub c} degradation behavior under transverse tension loading in different CC tape structure. • Weibull distribution analysis applied on delamination mechanism of CC tape. • Delamination mechanism on CC tapes depending on copper lamination type. • SEM and WDS mapping analysis of delamination sites under transverse loading. - Abstract: Laminated HTS coated conductor (CC) tapes having a unique multi-layer structure made them vulnerable when exposed to transverse loading. Electromechanical transport properties of these CC tapes can be affected by excessive transverse stresses. Due to the coefficient of thermal expansion (CTE) mismatch and incompatibility among constituent materials used in coil applications, delamination among layers occurs and causes critical current, I{sub c} degradation in the CC tapes. In this study, the delamination behaviors in copper (Cu) solder-laminated CC tapes by soldering and surround Cu-stabilized ones by electroplating under transverse tension loading were investigated. Similarly to the surround Cu-stabilized CC tapes in our previous reports, the Cu solder-laminated CC tapes also showed an abrupt and gradual I{sub c} degradation behavior. However, the Cu solder-laminated CC tapes showed different delamination morphologies as compared to the surround Cu-stabilized CC tapes; the superconducting side and the substrate side of the Cu solder laminated CC tapes were totally separated by delamination. On the other hand, the brass laminate did not show any significant effect on the delamination strength when it is added upon the surround Cu-stabilized CC tapes.

  3. Application of scanning laser Doppler vibrometry for delamination detection in composite structures

    Science.gov (United States)

    Kudela, Pawel; Wandowski, Tomasz; Malinowski, Pawel; Ostachowicz, Wieslaw

    2017-12-01

    In this paper application of scanning laser Doppler vibrometry for delamination detection in composite structures was presented. Delamination detection was based on a guided wave propagation method. In this papers results from numerical and experimental research were presented. In the case of numerical research, the Spectral Element Method (SEM) was utilized, in which a mesh was composed of 3D spectral elements. SEM model included also a piezoelectric transducer. In the experimental research guided waves were excited using the piezoelectric transducer whereas the sensing process was conducted using scanning laser Doppler vibrometer (SLDV). Analysis of guided wave propagation and its interaction with delamination was based on a full wavefield approach. Attention was focused on interactions of guided waves with delamination manifested by A0 mode reflection, A0 mode entrapment, and S0/A0 mode conversion. Delamination was simulated by a teflon insert located between plies of composite material. Results of interaction with symmetrically and nonsymmetrical placed delamination (in respect to the composite sample thickness) were presented. Moreover, the authors investigated different size of delaminations. Damage detection was based on a new signal processing algorithm proposed by the authors. In this approach the weighted RMS was utilized selectively. It means that the summation in RMS formula was performed only for a specially selected time instances. Results for simple composite panels, panel with honeycomb core, and real stiffened composite panel from the aircraft were presented.

  4. Optimization of Cutting Parameters on Delamination of Drilling Glass-Polyester Composites

    Directory of Open Access Journals (Sweden)

    Majid Habeeb Faidh-Allah

    2018-02-01

    Full Text Available This paper attempted to study the effect of cutting parameters (spindle speed and feed rate on delamination phenomena during the drilling glass-polyester composites. Drilling process was done by CNC machine with 10 mm diameter of high-speed steel (HSS drill bit. Taguchi technique with L16 orthogonal layout was used to analyze the effective parameters on delamination factor. The optimal experiment was no. 13 with spindle speed 1273 rpm and feed 0.05 mm/rev with minimum delamination factor 1.28.

  5. Characterization of Mode 1 and Mode 2 delamination growth and thresholds in graphite/peek composites

    Science.gov (United States)

    Martin, Roderick H.; Murri, Gretchen B.

    1988-01-01

    Composite materials often fail by delamination. The onset and growth of delamination in AS4/PEEK, a tough thermoplastic matrix composite, was characterized for mode 1 and mode 2 loadings, using the Double Cantilever Beam (DCB) and the End Notched Flexure (ENF) test specimens. Delamination growth per fatigue cycle, da/dN, was related to strain energy release rate, G, by means of a power law. However, the exponents of these power laws were too large for them to be adequately used as a life prediction tool. A small error in the estimated applied loads could lead to large errors in the delamination growth rates. Hence strain energy release rate thresholds, G sub th, below which no delamination would occur were also measured. Mode 1 and 2 threshold G values for no delamination growth were found by monitoring the number of cycles to delamination onset in the DCB and ENF specimens. The maximum applied G for which no delamination growth had occurred until at least 1,000,000 cycles was considered the threshold strain energy release rate. Comments are given on how testing effects, facial interference or delamination front damage, may invalidate the experimental determination of the constants in the expression.

  6. Cartilage Delamination Flap Mimicking a Torn Medial Meniscus

    Directory of Open Access Journals (Sweden)

    Gan Zhi-Wei Jonathan

    2016-01-01

    Full Text Available We report a case of a chondral delamination lesion due to medial parapatellar plica friction syndrome involving the medial femoral condyle. This mimicked a torn medial meniscus in clinical and radiological presentation. Arthroscopy revealed a chondral delamination flap, which was debrided. Diagnosis of chondral lesions in the knee can be challenging. Clinical examination and MRI have good accuracy for diagnosis and should be used in tandem. Early diagnosis and treatment of chondral lesions are important to prevent progression to early osteoarthritis.

  7. Local Guided Wavefield Analysis for Characterization of Delaminations in Composites

    Science.gov (United States)

    Rogge, Matthew D.; Campbell Leckey, Cara A.

    2012-01-01

    Delaminations in composite laminates resulting from impact events may be accompanied by minimal indication of damage at the surface. As such, inspection techniques are required to ensure defects are within allowable limits. Conventional ultrasonic scanning techniques have been shown to effectively characterize the size and depth of delaminations but require physical contact with the structure. Alternatively, a noncontact scanning laser vibrometer may be used to measure guided wave propagation in the laminate structure. A local Fourier domain analysis method is presented for processing guided wavefield data to estimate spatially-dependent wavenumber values, which can be used to determine delamination depth. The technique is applied to simulated wavefields and results are analyzed to determine limitations of the technique with regards to determining defect size and depth. Finally, experimental wavefield data obtained in quasi-isotropic carbon fiber reinforced polymer (CFRP) laminates with impact damage is analyzed and wavenumber is measured to an accuracy of 8.5% in the region of shallow delaminations. Keywords: Ultrasonic wavefield imaging, Windowed Fourier transforms, Guided waves, Structural health monitoring, Nondestructive evaluation

  8. DELAMINATION PREDICTION IN DRILLING OF CFRP COMPOSITES USING ARTIFICIAL NEURAL NETWORK

    Directory of Open Access Journals (Sweden)

    K. PALANIKUMAR

    2011-04-01

    Full Text Available Carbon fibre reinforced plastic (CFRP materials play a major role in the applications of aeronautic, aerospace, sporting and transportation industries. Machining is indispensible and hence drilling of CFRP materials is considered in this present study with respect to spindle speed in rpm, drill size in mm and feed in mm/min. Delamination is one of the major defects to be dealt with. The experiments are carried out using computer numerical control machine and the results are applied to an artificial neural network (ANN for the prediction of delamination factor at the exit plane of the CFRP material. It is found that ANN model predicts the delamination for any given set of machining parameters with a maximum error of 0.81% and a minimum error of 0.03%. Thus an ANN model is highly suitable for the prediction of delamination in CFRP materials.

  9. Modeling Quasi-Static and Fatigue-Driven Delamination Migration

    Science.gov (United States)

    De Carvalho, N. V.; Ratcliffe, J. G.; Chen, B. Y.; Pinho, S. T.; Baiz, P. M.; Tay, T. E.

    2014-01-01

    An approach was proposed and assessed for the high-fidelity modeling of progressive damage and failure in composite materials. It combines the Floating Node Method (FNM) and the Virtual Crack Closure Technique (VCCT) to represent multiple interacting failure mechanisms in a mesh-independent fashion. Delamination, matrix cracking, and migration were captured failure and migration criteria based on fracture mechanics. Quasi-static and fatigue loading were modeled within the same overall framework. The methodology proposed was illustrated by simulating the delamination migration test, showing good agreement with the available experimental data.

  10. Cathodic delamination: Quantification of ionic transport rates along coating-steel interfaces

    DEFF Research Database (Denmark)

    Sørensen, Per Aggerholm; Dam-Johansen, Kim; Erik Weinell, Claus

    2010-01-01

    So-called cathodic delamination is one of the major modes of failure for organic coatings immersed in electrolyte solutions (e.g. seawater). Cathodic delamination occurs as a result of the electrochemical reactions. which takes place on a corroding steel surface. This means that reactants must co...

  11. Aerogel to simulate delamination and porosity defects in carbon-fiber reinforced polymer composites

    Science.gov (United States)

    Juarez, Peter; Leckey, Cara A. C.

    2018-04-01

    Representative defect standards are essential for the validation and calibration of new and existing inspection techniques. However, commonly used methods of simulating delaminations in carbon-fiber reinforced polymer (CFRP) composites do not accurately represent the behavior of the real-world defects for several widely-used NDE techniques. For instance, it is common practice to create a delamination standard by inserting Polytetrafluoroethylene (PTFE) in between ply layers. However, PTFE can transmit more ultrasonic energy than actual delaminations, leading to an unrealistic representation of the defect inspection. PTFE can also deform/wrinkle during the curing process and has a thermal effusivity two orders of magnitude higher than air (almost equal to that of a CFRP). It is therefore not effective in simulating a delamination for thermography. Currently there is also no standard practice for producing or representing a known porosity in composites. This paper presents a novel method of creating delamination and porosity standards using aerogel. Insertion of thin sheets of solid aerogel between ply layers during layup is shown to produce air-gap-like delaminations creating realistic ultrasonic and thermographic inspection responses. Furthermore, it is shown that depositing controlled amounts of aerogel powder can represent porosity. Micrograph data verifies the structural integrity of the aerogel through the composite curing process. This paper presents data from multiple NDE methods, including X-ray computed tomography, immersion ultrasound, and flash thermography to the effectiveness of aerogel as a delamination and porosity simulant.

  12. Vibration of a Laminated Beam with a Delamination Including Contact Effects

    Directory of Open Access Journals (Sweden)

    W. Ostachowicz

    2004-01-01

    Full Text Available Certain results are presented in this paper on damped vibration of a laminated cantilever beam with a single closing delamination. In order to investigate this task the finite element method has been applied in the current study. For modelling the beam higher order shear deformation beam finite elements have been used. The vibration of the beam is investigated in the time domain using a dynamic contact algorithm developed by the authors. The algorithm is based on the Newmark method and also incorporates a Newton-Raphson based procedure for resolving the equation of motion. The time series obtained from solving the equation of motion have been subsequently analysed in the frequency domain by using FFT (Fast Fourier Transform. The vibration responses of the beam due to various harmonic and impulse excitations, at different delamination locations, and for different delamination lengths, as well as changes in the dissipation of damping energy due to the delamination, have all been considered in the paper.

  13. Effects of surface roughness, texture and polymer degradation on cathodic delamination of epoxy coated steel samples

    International Nuclear Information System (INIS)

    Khun, N.W.; Frankel, G.S.

    2013-01-01

    Highlights: ► Cathodic delamination of epoxy coated steel samples was studied using SKP. ► Delamination of the coating decreased with increased substrate surface roughness. ► Delamination of the coating was faster on the substrate with parallel surface scratches. ► Delamination of the coating exposed to weathering conditions increased with prolonged exposure. - Abstract: The Scanning Kelvin Probe (SKP) technique was used to investigate the effects of surface roughness, texture and polymer degradation on cathodic delamination of epoxy coated steel. The cathodic delamination rate of the epoxy coatings dramatically decreased with increased surface roughness of the underlying steel substrate. The surface texture of the steel substrates also had a significant effect in that samples with parallel abrasion lines exhibiting faster cathodic delamination in the direction of the lines compared to the direction perpendicular to the lines. The cathodic delamination kinetics of epoxy coatings previously exposed to weathering conditions increased with prolonged exposure due to pronounced polymer degradation. SEM observation confirmed that the cyclic exposure to UV radiation and water condensation caused severe deterioration in the polymer structures with surface cracking and erosion. The SKP results clearly showed that the cathodic delamination of the epoxy coatings was significantly influenced by the surface features of the underlying steel substrates and the degradation of the coatings.

  14. Characterization of Mode I and Mode II delamination growth and thresholds in AS4/PEEK composites

    Science.gov (United States)

    Martin, Roderick H.; Murri, Gretchen Bostaph

    1990-01-01

    Composite materials often fail by delamination. The onset and growth of delamination in AS4/PEEK, a tough thermoplastic matrix composite, was characterized for mode 1 and mode 2 loadings, using the Double Cantilever Beam (DCB) and the End Notched Flexure (ENF) test specimens. Delamination growth per fatigue cycle, da/dN, was related to strain energy release rate, G, by means of a power law. However, the exponents of these power laws were too large for them to be adequately used as a life prediction tool. A small error in the estimated applied loads could lead to large errors in the delamination growth rates. Hence strain energy release rate thresholds, G sub th, below which no delamination would occur were also measured. Mode 1 and 2 threshold G values for no delamination growth were found by monitoring the number of cycles to delamination onset in the DCB and ENF specimens. The maximum applied G for which no delamination growth had occurred until at least 1,000,000 cycles was considered the threshold strain energy release rate. Comments are given on how testing effects, facial interference or delamination front damage, may invalidate the experimental determination of the constants in the expression.

  15. The effect of delaminations on local buckling in wind turbine blades

    DEFF Research Database (Denmark)

    Haselbach, Philipp Ulrich; Bitsche, Robert; Branner, Kim

    2015-01-01

    In this article the effect of delaminations on the load carrying capacity of a large wind turbine blade is studied numerically. For this purpose an 8.65 m long blade section with different initial delaminations in the main spar was subjected to a flapwise dominated bending moment. The model...

  16. Piecewise delamination of Moroccan lithosphere from beneath the Atlas Mountains

    Science.gov (United States)

    Bezada, M. J.; Humphreys, E. D.; Davila, J. M.; Carbonell, R.; Harnafi, M.; Palomeras, I.; Levander, A.

    2014-04-01

    The elevation of the intracontinental Atlas Mountains of Morocco and surrounding regions requires a mantle component of buoyancy, and there is consensus that this buoyancy results from an abnormally thin lithosphere. Lithospheric delamination under the Atlas Mountains and thermal erosion caused by upwelling mantle have each been suggested as thinning mechanisms. We use seismic tomography to image the upper mantle of Morocco. Our imaging resolves the location and shape of lithospheric cavities and of delaminated lithosphere ˜400 km beneath the Middle Atlas. We propose discontinuous delamination of an intrinsically unstable Atlas lithosphere, enabled by the presence of anomalously hot mantle, as a mechanism for producing the imaged structures. The Atlas lithosphere was made unstable by a combination of tectonic shortening and eclogite loading during Mesozoic rifting and Cenozoic magmatism. The presence of hot mantle sourced from regional upwellings in northern Africa or the Canary Islands enhanced the instability of this lithosphere. Flow around the retreating Alboran slab focused upwelling mantle under the Middle Atlas, which we infer to be the site of the most recent delamination. The Atlas Mountains of Morocco stand as an example of large-scale lithospheric loss in a mildly contractional orogen.

  17. Edge delamination of composite laminates subject to combined tension and torsional loading

    Science.gov (United States)

    Hooper, Steven J.

    1990-01-01

    Delamination is a common failure mode of laminated composite materials. Edge delamination is important since it results in reduced stiffness and strength of the laminate. The tension/torsion load condition is of particular significance to the structural integrity of composite helicopter rotor systems. Material coupons can easily be tested under this type of loading in servo-hydraulic tension/torsion test stands using techniques very similar to those used for the Edge Delamination Tensile Test (EDT) delamination specimen. Edge delamination of specimens loaded in tension was successfully analyzed by several investigators using both classical laminate theory and quasi-three dimensional (Q3D) finite element techniques. The former analysis technique can be used to predict the total strain energy release rate, while the latter technique enables the calculation of the mixed-mode strain energy release rates. The Q3D analysis is very efficient since it produces a three-dimensional solution to a two-dimensional domain. A computer program was developed which generates PATRAN commands to generate the finite element model. PATRAN is a pre- and post-processor which is commonly used with a variety of finite element programs such as MCS/NASTRAN. The program creates a sufficiently dense mesh at the delamination crack tips to support a mixed-mode fracture mechanics analysis. The program creates a coarse mesh in those regions where the gradients in the stress field are low (away from the delamination regions). A transition mesh is defined between these regions. This program is capable of generating a mesh for an arbitrarily oriented matrix crack. This program significantly reduces the modeling time required to generate these finite element meshes, thus providing a realistic tool with which to investigate the tension torsion problem.

  18. Electrical Resistance Based Damage Modeling of Multifunctional Carbon Fiber Reinforced Polymer Matrix Composites

    Science.gov (United States)

    Hart, Robert James

    In the current thesis, the 4-probe electrical resistance of carbon fiber-reinforced polymer (CFRP) composites is utilized as a metric for sensing low-velocity impact damage. A robust method has been developed for recovering the directionally dependent electrical resistivities using an experimental line-type 4-probe resistance method. Next, the concept of effective conducting thickness was uniquely applied in the development of a brand new point-type 4-probe method for applications with electrically anisotropic materials. An extensive experimental study was completed to characterize the 4-probe electrical resistance of CFRP specimens using both the traditional line-type and new point-type methods. Leveraging the concept of effective conducting thickness, a novel method was developed for building 4-probe electrical finite element (FE) models in COMSOL. The electrical models were validated against experimental resistance measurements and the FE models demonstrated predictive capabilities when applied to CFRP specimens with varying thickness and layup. These new models demonstrated a significant improvement in accuracy compared to previous literature and could provide a framework for future advancements in FE modeling of electrically anisotropic materials. FE models were then developed in ABAQUS for evaluating the influence of prescribed localized damage on the 4-probe resistance. Experimental data was compiled on the impact response of various CFRP laminates, and was used in the development of quasi- static FE models for predicting presence of impact-induced delamination. The simulation-based delamination predictions were then integrated into the electrical FE models for the purpose of studying the influence of realistic damage patterns on electrical resistance. When the size of the delamination damage was moderate compared to the electrode spacing, the electrical resistance increased by less than 1% due to the delamination damage. However, for a specimen with large

  19. Buckling Analysis of Single and Multi Delamination In Composite Beam Using Finite Element Method

    Science.gov (United States)

    Simanjorang, Hans Charles; Syamsudin, Hendri; Giri Suada, Muhammad

    2018-04-01

    Delamination is one type of imperfection in structure which found usually in the composite structure. Delamination may exist due to some factors namely in-service condition where the foreign objects hit the composite structure and creates inner defect and poor manufacturing that causes the initial imperfections. Composite structure is susceptible to the compressive loading. Compressive loading leads the instability phenomenon in the composite structure called buckling. The existence of delamination inside of the structure will cause reduction in buckling strength. This paper will explain the effect of delamination location to the buckling strength. The analysis will use the one-dimensional modelling approach using two- dimensional finite element method.

  20. Cdc42/N-WASP signaling links actin dynamics to pancreatic β cell delamination and differentiation

    Science.gov (United States)

    Kesavan, Gokul; Lieven, Oliver; Mamidi, Anant; Öhlin, Zarah Löf; Johansson, Jenny Kristina; Li, Wan-Chun; Lommel, Silvia; Greiner, Thomas Uwe; Semb, Henrik

    2014-01-01

    Delamination plays a pivotal role during normal development and cancer. Previous work has demonstrated that delamination and epithelial cell movement within the plane of an epithelium are associated with a change in cellular phenotype. However, how this positional change is linked to differentiation remains unknown. Using the developing mouse pancreas as a model system, we show that β cell delamination and differentiation are two independent events, which are controlled by Cdc42/N-WASP signaling. Specifically, we show that expression of constitutively active Cdc42 in β cells inhibits β cell delamination and differentiation. These processes are normally associated with junctional actin and cell-cell junction disassembly and the expression of fate-determining transcription factors, such as Isl1 and MafA. Mechanistically, we demonstrate that genetic ablation of N-WASP in β cells expressing constitutively active Cdc42 partially restores both delamination and β cell differentiation. These findings elucidate how junctional actin dynamics via Cdc42/N-WASP signaling cell-autonomously control not only epithelial delamination but also cell differentiation during mammalian organogenesis. PMID:24449844

  1. Laser Doppler Vibrometer Based Examination of the Efficiency of Introducing Artificial Delaminations into Composite Shells

    Directory of Open Access Journals (Sweden)

    Kustroń Kamila

    2015-09-01

    Full Text Available During its operation, the laminate shell of the watercraft hull can be exposed to local stability losses caused by the appearance and development of delaminations. The sources of these delaminations are discontinuities, created both in the production process and as a result of bumps of foreign bodies into the hull in operation. In the environment of fatigue loads acting on the hull, the delaminations propagate and lead to the loss of load capacity of the hull structure. There is a need to improve diagnostic systems used in Structural Health Monitoring (SHM of laminate hull elements to detect and monitor the development of the delaminations. Effective diagnostic systems used for delamination assessment base on expert systems. Along with other tools, the expert diagnostic advisory systems make use of the non-destructive examination method which consists in generating elastic waves in the hull shell structure and observing their changes by comparing the recorded signal with damage patterns collected in the expert system database. This system requires introducing certain patterns to its knowledge base, based on the results of experimental examinations performed on specimens with implemented artificial delaminations. The article presents the results of the examination oriented on assessing the delaminations artificially generated in the structure of glass- and carbon-epoxy laminates by introducing local non-adhesive layers with the aid of thin polyethylene film, teflon insert, or thin layer of polyvinyl alcohol. The efficiency of each method was assessed using laser vibrometry. The effect of the depth of delamination position in the laminate on the efficiency of the applied method is documented as well.

  2. Controlled delamination of metal films by hydrogen loading

    Energy Technology Data Exchange (ETDEWEB)

    Nikitin, Eugen

    2008-11-18

    n this work we quantitatively determine the adhesion energy between metal films and their substrates. Therefore a new controlled buckling technique is established, applying the strong compressive in-plane stress that results in thin films clamped on rigid substrates during hydrogen loading. When the elastic energy stored in the H-loaded thin film exceeds the adhesion energy between film and substrate, delamination occurs. At the onset of delamination, a critical hydrogen concentration, a critical stress value and a critical bending of the substrate are present, which are quantitative measures for the adhesion energy and permit its calculation. As the critical values are determined at the onset of delamination, plastic deformation is negligible, which denies the quantitative determination of adhesion energies in conventional test setups. In multilayer-systems, adhesion energies between substrates and films that hardly absorb hydrogen can be measured by the controlled buckling technique, when the films of interest are coated with hydrogen absorbing films (active layer). The measurements are performed easily and can be repeated under the same test conditions, while variables such as the thickness of the coating materials or the boundary surface structure can be varied and optimized. In this work the adhesion energies of different materials on polycarbonate and niobium on sapphire are investigated. (orig.)

  3. Understanding mixed-mode cyclic fatigue delamination growth in unidirectional composites : An experimental approach

    NARCIS (Netherlands)

    Amaral, L.; Alderliesten, R.C.; Benedictus, R.

    2017-01-01

    Due to the lack of fundamental knowledge of the physics behind delamination growth, certification authorities currently require that composite structures in aircraft are designed such that any delamination will not grow. This usually leads to an overdesign of the structure, hampering weight

  4. Delamination of Pearlitic Steel Wires: The Defining Role of Prior-Drawing Microstructure

    Science.gov (United States)

    Durgaprasad, A.; Giri, S.; Lenka, S.; Sarkar, Sudip Kumar; Biswas, Aniruddha; Kundu, S.; Mishra, S.; Chandra, S.; Doherty, R. D.; Samajdar, I.

    2018-03-01

    This article reports the occasional (alignment of the pearlite: 22 ± 5 pct vs 34 ± 4 pct in the nondelaminated wires. Although all wires had similar through-thickness texture and stress gradients, delaminated wires had stronger gradients in composition and higher hardness across the ferrite-cementite interface. Carbide dissolution and formation of supersaturated ferrite were clearly correlated with delamination, which could be effectively mitigated by controlled laboratory annealing at 673 K. Direct observations on samples subjected to simple shear revealed significant differences in shear localizations. These were controlled by pearlite morphology and interlamellar spacing. Prior-drawing microstructure of coarse misaligned pearlite thus emerged as a critical factor in the wire drawing-induced delamination of the pearlitic wires.

  5. Delamination-Debond Behaviour of Composite T- Joints in Wind Turbine Blades

    International Nuclear Information System (INIS)

    Gulasik, H; Coker, D

    2014-01-01

    Wind turbine industry utilizes composite materials in turbine blade structural designs because of their high strength/stiffness to weight ratio. T-joint is one of the design configurations of composite wind turbine blades. T-joints consist of a skin panel and a stiffener co-bonded or co-cured together with a filler material between them. T-joints are prone to delaminations between skin/stiffener plies and debonds between skin-stiffener-filler interfaces. In this study, delamination/debond behavior of a co-bonded composite T-joint is investigated under 0° pull load condition by 2D finite element method. Using Abaqus® commercial FE software, zero-thickness cohesive elements are used to simulate delamination/debond in ply interfaces and bonding lines. Pulling load at 0° is applied and load-displacement behavior and failure scenario are observed. The failure sequence consists of debonding of filler/stringer interface during one load drop followed by a second drop in which the 2nd filler/stringer debonds, filler/skin debonding and skin delamination leading to total loss of load carrying capacity. This type of failure initiation has been observed widely in the literature. When the debond strength is increased 30%, failure pattern is found to change in addition to increasing the load capacity by 200% before total loss of loading carrying capacity occurs. Failure initiation and propagation behavior, initial and max failure loads and stress fields are affected by the property change. In all cases mixed-mode crack tip loading is observed in the failure initiation and propagation stages. In this paper, the detailed delamination/debonding history in T-joints is predicted with cohesive elements for the first time

  6. Hierarchical system for autonomous sensing-healing of delamination in large-scale composite structures

    International Nuclear Information System (INIS)

    Minakuchi, Shu; Sun, Denghao; Takeda, Nobuo

    2014-01-01

    This study combines our hierarchical fiber-optic-based delamination detection system with a microvascular self-healing material to develop the first autonomous sensing-healing system applicable to large-scale composite structures. In this combined system, embedded vascular modules are connected through check valves to a surface-mounted supply tube of a pressurized healing agent while fiber-optic-based sensors monitor the internal pressure of these vascular modules. When delamination occurs, the healing agent flows into the vascular modules breached by the delamination and infiltrates the damage for healing. At the same time, the pressure sensors identify the damaged modules by detecting internal pressure changes. This paper begins by describing the basic concept of the combined system and by discussing the advantages that arise from its hierarchical nature. The feasibility of the system is then confirmed through delamination infiltration tests. Finally, the hierarchical system is validated in a plate specimen by focusing on the detection and infiltration of the damage. Its self-diagnostic function is also demonstrated. (paper)

  7. Cathodic delamination: Quantification of ionic transport rates along coating-steel interfaces

    DEFF Research Database (Denmark)

    Sørensen, P.A.; Dam-Johansen, Kim; Weinell, C.E.

    2010-01-01

    So-called cathodic delamination is one of the major modes of failure for organic coatings immersed in electrolyte solutions (e.g. seawater). Cathodic delamination occurs as a result of the electrochemical reactions, which takes place on a corroding steel surface. This means that reactants must...... continuously be transported from the bulk solution to the cathodic areas. The transport of sodium ions from a defect in the coating to the cathodic areas is generally considered the rate-determining step for cathodic delamination because the transport of oxygen and water through the coating is sufficient...... for the corrosion processes. In this work, a novel practical method, which allows direct estimation of the apparent diffusion coefficient of sodium ions in the ultrathin aqueous layer at the coating-steel interface, is described. The apparent diffusion coefficients estimated are of similar magnitude as previously...

  8. Development, test-retest reliability, and construct validity of the resistance training skills battery.

    Science.gov (United States)

    Lubans, David R; Smith, Jordan J; Harries, Simon K; Barnett, Lisa M; Faigenbaum, Avery D

    2014-05-01

    The aim of this study was to describe the development and assess test-retest reliability and construct validity of the Resistance Training Skills Battery (RTSB) for adolescents. The RTSB provides an assessment of resistance training skill competency and includes 6 exercises (i.e., body weight squat, push-up, lunge, suspended row, standing overhead press, and front support with chest touches). Scoring for each skill is based on the number of performance criteria successfully demonstrated. An overall resistance training skill quotient (RTSQ) is created by adding participants' scores for the 6 skills. Participants (44 boys and 19 girls, mean age = 14.5 ± 1.2 years) completed the RTSB on 2 occasions separated by 7 days. Participants also completed the following fitness tests, which were used to create a muscular fitness score (MFS): handgrip strength, timed push-up, and standing long jump tests. Intraclass correlation (ICC), paired samples t-tests, and typical error were used to assess test-retest reliability. To assess construct validity, gender and RTSQ were entered into a regression model predicting MFS. The rank order repeatability of the RTSQ was high (ICC = 0.88). The model explained 39% of the variance in MFS (p ≤ 0.001) and RTSQ (r = 0.40, p ≤ 0.001) was a significant predictor. This study has demonstrated the construct validity and test-retest reliability of the RTSB in a sample of adolescents. The RTSB can reliably rank participants in regards to their resistance training competency and has the necessary sensitivity to detect small changes in resistance training skill proficiency.

  9. Fiber Optic Thermal Detection of Composite Delaminations

    Science.gov (United States)

    Wu, Meng-Chou; Winfree, William P.

    2011-01-01

    A recently developed technique is presented for thermographic detection of delaminations in composites by performing temperature measurements with fiber optic Bragg gratings. A single optical fiber with multiple Bragg gratings employed as surface temperature sensors was bonded to the surface of a composite with subsurface defects. The investigated structure was a 10-ply composite specimen with prefabricated delaminations of various sizes and depths. Both during and following the application of a thermal heat flux to the surface, the individual Bragg grating sensors measured the temporal and spatial temperature variations. The data obtained from grating sensors were analyzed with thermal modeling techniques of conventional thermography to reveal particular characteristics of the interested areas. Results were compared and found to be consistent with the calculations using numerical simulation techniques. Also discussed are methods including various heating sources and patterns, and their limitations for performing in-situ structural health monitoring.

  10. Energy based study of quasi-static delamination as a low cycle fatigue process

    NARCIS (Netherlands)

    Amaral, L.; Yao, L.; Alderliesten, R.C.; Benedictus, R.

    2015-01-01

    This work proposes to treat quasi-static mode I delamination growth of CFRP as a low-cycle fatigue process. To this end, mode I quasi-static and fatigue delamination tests were performed. An average physical Strain Energy Release Rate (SERR), derived from an energy balance, is used to characterize

  11. Impulse response measurements as dependent on crack depth. Delamination

    International Nuclear Information System (INIS)

    Ulriksen, Peter

    2011-02-01

    The purpose of the project is to investigate the impulse-response method's ability to detect delamination at different depths. This method is of particular interest, since some of it's realizations strongly resembles established methods like 'bomknackning' . Since the personnel that will be responsible for future measurements with new technology, should feel confidence in new methods, it is an advantage if the new methods connect to older, accepted methods. The project consists of three parts and a fourth is planned. The first part of the investigation is made with a vibrator connected to an impedance head which in turn is connected to the surface of the concrete test specimen with internal delaminations at different depths. The vibrator is controlled by a dynamic signal analyze, which also measures the force- and acceleration signals from the impedance head and convert them to impedance. Since the impedance head must be glued to the surface of the concrete this method is only of laboratory interest. This method gives a complete description of the behavior of the concrete for the frequencies investigated. Thus in following investigations the frequencies of interest are known. From the experiment it follows that delamination down to a depth of 80-100 mm can be detected through a clear and solitary resonance peak. This resonance frequency is a function of concrete slab thickness and extension, so if the extension can be measured it may be possible to calculate depth. The second part of the investigation is about using an instrumented hammer to hit the different delamination specimens. The hammer is equipped with a force transducer giving an opportunity to measure the force exerted by the strike against the concrete surface. When a hammer is struck against a concrete surface a spectrum of vibrations is created, dependent on the weight of the hammer and the elasticity of the concrete. A light hammer generates higher frequencies than a heavy one. Three different hammer

  12. Calibration of a finite element composite delamination model by experiments

    DEFF Research Database (Denmark)

    Gaiotti, M.; Rizzo, C.M.; Branner, Kim

    2013-01-01

    This paper deals with the mechanical behavior under in plane compressive loading of thick and mostly unidirectional glass fiber composite plates made with an initial embedded delamination. The delamination is rectangular in shape, causing the separation of the central part of the plate into two...... distinct sub-laminates. The work focuses on experimental validation of a finite element model built using the 9-noded MITC9 shell elements, which prevent locking effects and aiming to capture the highly non linear buckling features involved in the problem. The geometry has been numerically defined...

  13. Influence of previous experience on resistance training on reliability of one-repetition maximum test.

    Science.gov (United States)

    Ritti-Dias, Raphael Mendes; Avelar, Ademar; Salvador, Emanuel Péricles; Cyrino, Edilson Serpeloni

    2011-05-01

    The 1-repetition maximum test (1RM) has been widely used to assess maximal strength. However, to improve accuracy in assessing maximal strength, several sessions of the 1RM test are recommended. The aim of this study was to analyze the influence of previous resistance training experience on the reliability of 1RM test. Thirty men were assigned to the following 2 groups according to their previous resistance training experience: no previous resistance training experience (NOEXP) and more than 24 months of resistance training experience (EXP). All subjects performed the 1RM tests in bench press and squat in 4 sessions on distinct days. There was a significant session × group effect in bench press (F = 3.09; p reliability of the 1RM test is influenced by the subject's previous experience in resistance training. Subjects without experience in resistance training require more practice and familiarization and show greater increases in maximal strength between sessions than subjects with previous experience in resistance training.

  14. Delamination propensity of pharmaceutical glass containers by accelerated testing with different extraction media.

    Science.gov (United States)

    Guadagnino, Emanuel; Zuccato, Daniele

    2012-01-01

    The delamination of pharmaceutical glass is a serious issue, as it can cause glass particles to appear in vials, a problem that has forced a number of drug product recalls in recent years. In Type I pharmaceutical glass vials, delamination occurs generally at the bottom and shoulder, where extensive flaming during the conversion process can favor a strong evaporation of alkali and borate species and the formation of heavily enriched silica layers. The contact with parenteral preparations dissolved in an alkaline medium increases the rate of glass corrosion, while the differential hydration of these layers can cause the detachment of flakes. The purpose of this study was to investigate the effect of the pH and the composition of the extraction solutions on the propensity of different glass types to delaminate. Repeated autoclave extractions at 121 °C were carried out on different glass types with different extraction media, including organic extractants like citric and glutaric acid. When vials were in contact with alkaline solutions and similarly aggressive media, an increase in silica extraction values indicated glass corrosion and an increasing risk for further delamination. Under such conditions expansion 33 glass is extensively corroded, showing high silica concentration and heavy flaking as compared to other glass types. Sulfur-treated glass also showed early flaking, even if SiO(2) concentration was very low. A similar ranking was observed with extractions carried out with glutaric and citric acids, but at far much higher SiO(2) concentration levels. Extractions with 0.9% KCl solution can be used as an accelerated test to highlight the propensity of a glass to delaminate, but in no case it can be taken as a guarantee that the glass will not delaminate when exposed to the pharmaceutical drug, whose extraction ability requires case-by-case study. How can injectable drug manufacturers prevent glass delamination? The issue of delamination is a serious one, as it

  15. Acoustic Emission based on sentry function to monitor the initiation of delamination in composite materials

    International Nuclear Information System (INIS)

    Bakhtiary Davijani, A.A.; Hajikhani, M.; Ahmadi, M.

    2011-01-01

    Research highlights: → Constant load does not confirm constant damage in composite materials. → Different damages have different AE events. → Sentry function is a useful tool to monitor the initiation of damage in delamination. → The less sentry function number is the more damage the material has endured. -- Abstract: Delamination is the most common failure mode in composite materials, since it will result in the reduction of stiffness and can grow throughout other layers. Delamination is consisted of two main stages including initiation and propagation. Understanding the behavior of the material in these zones is very important, hence it has been thoroughly studied by different methods such as numerical methods, Acoustic Emission (AE), and modeling. Between these two regions initiation is a more vital stage in the delamination of the material. Once initiation occurs, which normally requires greater amount of force, cracks can easily propagate through the structure with little force and cause the failure of the structure. A better knowledge of initiation can lead to better design and production of stronger materials. Additionally, more knowledge about crack initiation and its internal microevents would help improve other parameters and result in higher strength against crack initiation. AE is a suitable method for in situ monitoring of damage in composite materials. In this study, AE was applied to test different glass/epoxy specimens which were loaded under mode I delamination. A function that combines AE and mechanical information is employed to investigate the initiation of delamination. Scanning electron microscope (SEM) was used to verify the results of this function. It is shown that this method is an appropriate technique to monitor the behavior of the initiation of delamination.

  16. Delamination of hexagonal boron nitride in a stirred media mill

    International Nuclear Information System (INIS)

    Damm, C.; Körner, J.; Peukert, W.

    2013-01-01

    A scalable process for delamination of hexagonal boron nitride in an aqueous solution of the non-ionic surfactant TWEEN85 using a stirred media mill is presented. The size of the ZrO 2 beads used as grinding media governs the dimensions of the ground boron nitride particles as atomic force microscopic investigations (AFM) reveal: the mean flakes thickness decreases from 3.5 to 1.5 nm and the ratio between mean flake area and mean flake thickness increases from 2,200 to 5,800 nm if the grinding media size is reduced from 0.8 to 0.1 mm. This result shows that a high number of stress events in combination with low stress energy (small grinding media) facilitate delamination of the layered material whereas at high stress energies in combination with a low number of stress events (large grinding media) breakage of the layers dominates over delamination. The results of particle height analyses by AFM show that few-layer structures have been formed by stirred media milling. This result is in agreement with the layer thickness dependence of the delamination energy for hexagonal boron nitride. The concentration of nanoparticles remaining dispersed after centrifugation of the ground suspension increases with grinding time and with decreasing grinding media size. After 5 h of grinding using 0.1 mm ZrO 2 grinding media the yield of nanoparticle formation is about 5 wt%. The nanoparticles exhibit the typical Raman peak for hexagonal boron nitride at 1,366 cm −1 showing that the in-plane order in the milled platelets is remained.

  17. Mechanism of Electrochemical Delamination of Two-Dimensional Materials from Their Native Substrates by Bubbling.

    Science.gov (United States)

    Sun, Jie; Fan, Xing; Guo, Weiling; Liu, Lihui; Liu, Xin; Deng, Jun; Xu, Chen

    2015-12-16

    A capacitor-based circuit model is proposed to explain the electrochemical delamination of two-dimensional materials from their native substrates where produced gas bubbles squeeze into the interface. The delamination is actually the electric breakdown of the capacitor formed between the solution and substrate. To facilitate the procedure, the backside of the ubstrate has to be shielded so that the capacitor breakdown voltage can be reached. The screening effect can be induced either by nonreactive ions around the electrode or, more effectively, by an undetachable insulator. This mechanism serves as a guideline for the surface science and applications involving the bubbling delamination.

  18. Cyclic delamination behavior of plasma-sprayed hydroxyapatite coating on Ti-6Al-4V substrates in simulated body fluid.

    Science.gov (United States)

    Otsuka, Yuichi; Kawaguchi, Hayato; Mutoh, Yoshiharu

    2016-10-01

    This study aimed to clarify the effect of a simulated body fluid (SBF) on the cyclic delamination behavior of a plasma-sprayed hydroxapatite (HAp) coating. A HAp coating is deposited on the surfaces of surgical metallic materials in order to enhance the bond between human bone and such surfaces. However, the HAp coating is susceptible to delamination by cyclic loading from the patient's gait. Although hip joints are subjected to both positive and negative moments, only the effects of tensile bending stresses on vertical crack propagation behavior have been investigated. Thus, the cyclic delamination behavior of a HAp coating was observed at the stress ratio R=-1 in order to determine the effects of tensile/compressive loading on the delamination behavior. The delamination growth rate increased with SBF immersion, which decreased the delamination life. Raman spectroscopy analysis revealed that the selective phase dissolution in the HAp coating was promoted at interfaces. Finite element analysis revealed that the energy release rate Gmax showed a positive value even in cases with compressive loading, which is a driving force for the delamination of a HAp coating. A prediction model for the delamination growth life was developed that combines a fracture mechanics parameter with the assumed stress-dependent dissolution rate. The predicted delamination life matched the experimental data well in cases of lower stress amplitudes with SBF. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Synthesis of mullite nanometers microwave from bentonite delaminated

    International Nuclear Information System (INIS)

    Gomes, J.; Azevedo, N.A.; Vieira, D.A.; Neves, G.A.; Santana, L.N.L.; Menezes, R.R.

    2011-01-01

    The smectite clays present as lamellar structure is formed by two layers of silica tetrahedrons and one layer of aluminum octahedra, which can be individually delaminated, reaching a thickness of about 1mm. Mullite is the only thermodynamically stable crystalline phase of SiO 2 and Al2O 3 system and can be synthesized from minerals that exhibit these oxides in its composition. The microwave synthesis offers advantages over conventional methods, the heating is rapid and uniform, avoiding an undesirable grain growth. This study aims to obtain nanometric mullite from bentonites delamined subjected to microwave heating. The samples were initially treated, then rehydrated, frozen and deagglomeration in a ball mill for 4 and 8 hours. Subsequently subjected to centrifugation, drying and microwave heating. The results showed that nano-mullite was obtained for samples subjected to longer heating and dispersions. (author)

  20. Peeling back the lithosphere: Controlling parameters, surface expressions and the future directions in delamination modeling

    Science.gov (United States)

    Göğüş, Oğuz H.; Ueda, Kosuke

    2018-06-01

    Geodynamical models investigate the rheological and physical properties of the lithosphere that peels back (delaminates) from the upper-middle crust. Meanwhile, model predictions are used to relate to a set of observations in the geological context to the test the validity of delamination. Here, we review numerical and analogue models of delamination from these perspectives and provide a number of first-order topics which future modeling studies may address. Models suggest that the presence of the weak lower crust that resides between the strong mantle lithosphere (at least 100 times more viscous/stronger) and the strong upper crust is necessary to develop delamination. Lower crustal weakening may be induced by melt infiltration, shear heating or it naturally occurs through the jelly sandwich type strength profile of the continental lithosphere. The negative buoyancy of the lithosphere required to facilitate the delamination is induced by the pre-existing ocean subduction and/or the lower crustal eclogitization. Surface expression of the peeling back lithosphere has a distinct transient and migratory imprint on the crust, resulting in rapid surface uplift/subsidence, magmatism, heating and shortening/extension. New generation of geodynamical experiments can explain how different types of melting (e.g hydrated, dry melting) occurs with delamination. Reformation of the lithosphere after removal, three dimensional aspects, and the termination of the process are key investigation areas for future research. The robust model predictions, as with other geodynamic modeling studies should be reconciled with observations.

  1. Numerical models of delamination behavior in 2G HTS tapes under transverse tension and peel

    Science.gov (United States)

    Duan, Yujie; Ta, Wurui; Gao, Yuanwen

    2018-02-01

    In extreme operating environments, delamination in 2G HTS tapes occurs within and/or near the superconductor layer from high transverse tensile stresses caused by fabrication, Lorentz forces and thermal mismatch, etc. Generally, transverse opening and peeling off are the main delamination modes, and are always studied in anvil and peel tests, respectively. Numerical models of these modes for 2G HTS tape are presented wherein the mixed-mode traction-separation law at the interface of the silver and superconductor layers is considered. Plastic deformations of copper, silver, and Hastelloy® in the HTS tape are taken into account. The results obtained from the transverse opening model show that the maximum average tensile stress is smaller than the delamination tensile strength because delamination is asynchronous in the tape. When a crack appears in the tape, only a small stress ( ≤ 1 MPa) is required to expand the crack to other stress free areas through peeling. Using the peeling model, the dependency of the peel strength on peeling angle is investigated under constant fracture toughness. Peel strength decreases with the peeling angle until the minimum value is reached at 150°, and thereafter increases slightly. Other results indicate that peel strength depends strongly on delamination strength, fracture toughness, and thickness of copper layer. The fracture toughness of the delamination interface, which is difficult to obtain by experiment, can be extracted using the present model.

  2. Numerical evaluation of delamination in CFRP laminates by stereo X-ray pictures

    International Nuclear Information System (INIS)

    Kunoo, Kazuo; Uda, Nobuhide; Ono, Kousei; Onohara, Kaoru; Takahashi, Toshiaki; Tanaka, Hisahiro.

    1989-01-01

    This paper presents a method for quantifying damage in composite laminates by stereo X-ray pictures. A three dimensional image of delamination, which is one of the characteristic types of damage in composite laminates can be reconstructed with this method. A digital image processing technique is used to analyze X-ray pictures. Experimental results of reconstructing delaminations in carbon/epoxy cross-ply laminates show that this method is accurate enough for practical usage. (author)

  3. Piecewise Delamination Drives Uplift in the Atlas Mountains Region of Morocco

    Science.gov (United States)

    Bezada, M. J.; Humphreys, E.; Martin Davila, J.; mimoun, H.; Josep, G.; Palomeras, I.

    2013-12-01

    The elevation of the intra-continental Atlas Mountains of Morocco and surrounding regions requires a mantle component of buoyancy, and there is consensus that this buoyancy results from an abnormally thin lithosphere. Lithospheric delamination under the Atlas Mountains and thermal erosion caused by upwelling mantle have each been suggested as thinning mechanisms. We use seismic tomography to image the upper mantle of Morocco by inverting teleseimic p-wave delay times, complemented with local delays, recorded on a dense array of stations in the Iberian peninsula and Morocco. A surface wave model provides constraint on the shallower layers. We determine the geometry of lithospheric cavities and mantle upwelling beneath the Middle Atlas and central High Atlas, and image delaminated lithosphere at ~400 km beneath the Middle Atlas. We propose discontinuous delamination of an intrinsically unstable Atlas lithosphere, enabled by the presence of anomalously hot mantle, as a mechanism for producing the imaged structures. The Atlas lithosphere was made unstable by a combination of tectonic shortening and eclogite loading during Mesozoic rifting and Cenozoic magmatism. The presence of hot mantle, sourced from regional upwellings in northern Africa or the Canary Islands, enabled the mobilization of this lithosphere. Flow around the retreating Alboran slab focused upwelling mantle under the Middle Atlas, where we image the most recent delamination. The Atlas Mountains of Morocco stand as an example of mantle-generated uplift and large-scale lithospheric loss in a mildly contractional orogen.

  4. Mechanism of Electrochemical Delamination of Two-Dimensional Materials from Their Native Substrates by Bubbling

    Directory of Open Access Journals (Sweden)

    Jie Sun

    2015-12-01

    Full Text Available A capacitor-based circuit model is proposed to explain the electrochemical delamination of two-dimensional materials from their native substrates where produced gas bubbles squeeze into the interface. The delamination is actually the electric breakdown of the capacitor formed between the solution and substrate. To facilitate the procedure, the backside of the ubstrate has to be shielded so that the capacitor breakdown voltage can be reached. The screening effect can be induced either by nonreactive ions around the electrode or, more effectively, by an undetachable insulator. This mechanism serves as a guideline for the surface science and applications involving the bubbling delamination.

  5. Adhesion-delamination phenomena at the surfaces and interfaces in microelectronics and MEMS structures and packaged devices

    International Nuclear Information System (INIS)

    Khanna, V K

    2011-01-01

    Physico-chemical mechanisms of adhesion and debonding at the various surfaces and interfaces of semiconductor devices, integrated circuits and microelectromechanical systems are systematically examined, starting from chip manufacturing and traversing the process stages to the ultimate finished product. Sources of intrinsic and thermal stresses in these devices are pointed out. Thin film ohmic contacts to the devices call for careful attention. The role of an adhesion layer in multilayer metallization schemes is highlighted. In packaged devices, sites facing potential risks of delamination are indicated. As MEMS devices incorporate moving parts, there are additional issues due to adhesion of suspended structures to surfaces in the vicinity, both during chip fabrication and their subsequent operation. Proper surface treatments for preventing adhesion together with design considerations for overcoming stiction pave the way to reliable functioning of these devices. Adhesion-delamination issues in microelectronics and MEMS continue to pose significant challenges to both design and process engineers. This paper is an attempt to survey the adhesion characteristics of materials, their compatibilities and limitations and look at future research trends. In addition, it addresses some of the techniques for improved or reduced adhesion, as demanded by the situation. The paper encompasses fundamental aspects to contemporary applications.

  6. Progressive delamination in polymer matrix composite laminates: 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 delamination in polymer matrix composite laminates. The damage stages are quantified based on physics via composite mechanics while the degradation of the laminate behavior is quantified via the finite element method. The approach accounts for all types of composite behavior, laminate configuration, load conditions, and delamination processes starting from damage initiation, to unstable propagation, and to laminate fracture. Results of laminate fracture in composite beams, panels, plates, and shells are presented to demonstrate the effectiveness and versatility of this new approach.

  7. Effect of Location of Delamination on Free Vibration of Cross-Ply Conical Shells

    Directory of Open Access Journals (Sweden)

    Sudip Dey

    2012-01-01

    Full Text Available Location of delamination is a triggering parameter for structural instability of laminated composites. In this paper, a finite element method is employed to determine the effects of location of delamination on free vibration characteristics of graphite-epoxy cross-ply composite pre-twisted shallow conical shells. The generalized dynamic equilibrium equation is derived from Lagrange's equation of motion neglecting Coriolis effect for moderate rotational speeds. The formulation is exercised by using an eight noded isoparametric plate bending element based on Mindlin's theory. Multi-point constraint algorithm is utilized to ensure the compatibility of deformation and equilibrium of resultant forces and moments at the delamination crack front. The standard eigen value problem is solved by applying the QR iteration algorithm. Finite element codes are developed to obtain the numerical results concerning the effects of location of delamination, twist angle and rotational speed on the natural frequencies of cross-ply composite shallow conical shells. The mode shapes are also depicted for a typical laminate configuration. Numerical results obtained from parametric studies of both symmetric and anti-symmetric cross-ply laminates are the first known non-dimensional natural frequencies for the type of analyses carried out here.

  8. Determination of a cohesive law for delamination modelling - Accounting for variation in crack opening and stress state across the test specimen width

    DEFF Research Database (Denmark)

    Joki, R. K.; Grytten, F.; Hayman, Brian

    2016-01-01

    by differentiating the fracture resistance with respect to opening displacement at the initial location of the crack tip, measured at the specimen edge. 2) Extend the bridging law to a cohesive law by accounting for crack tip fracture energy. 3) Fine-tune the cohesive law through an iterative modelling approach so......The cohesive law for Mode I delamination in glass fibre Non-Crimped Fabric reinforced vinylester is determined for use in finite element models. The cohesive law is derived from a delamination test based on DCB specimens loaded with pure bending moments taking into account the presence of large...... that the changing state of stress and deformation across the width of the test specimen is taken into account. The changing state of stress and deformation across the specimen width is shown to be significant for small openings (small fracture process zone size). This will also be important for the initial part...

  9. Nondestructive testing of delaminated interfaces between two materials using electromagnetic interrogation

    Science.gov (United States)

    Cakoni, Fioralba; de Teresa, Irene; Monk, Peter

    2018-06-01

    We consider the problem of detecting whether two materials that should be in contact have separated or delaminated using electromagnetic radiation. The interface damage is modeled as a thin opening between two materials of different electromagnetic properties. To derive a reconstruction algorithm that focuses on testing for the delamination at the interface between the two materials, we use the approximate asymptotic model for the forward problem derived in de Teresa (2017 PhD Thesis University of Delaware). In this model, the differential equations in the small opening are replaced by approximate transmission conditions for the electromagnetic fields across the interface. We also assume that the undamaged or background state is known and it is desired to find where the delamination has opened. We adapt the linear sampling method to this configuration in order to locate the damaged part of the interface from a knowledge of the scattered field and the undamaged configuration, but without needing to know the electromagnetic properties of the opening. Numerical examples are presented to validate our algorithm.

  10. Transient Dynamic Response of Delaminated Composite Rotating Shallow Shells Subjected to Impact

    Directory of Open Access Journals (Sweden)

    Amit Karmakar

    2006-01-01

    Full Text Available In this paper a transient dynamic finite element analysis is presented to study the response of delaminated composite pretwisted rotating shallow shells subjected to low velocity normal impact. Lagrange's equation of motion is used to derive the dynamic equilibrium equation and moderate rotational speeds are considered wherein the Coriolis effect is negligible. An eight noded isoparametric plate bending element is employed in the finite element formulation incorporating rotary inertia and effects of transverse shear deformation based on Mindlin's theory. To satisfy the compatibility of deformation and equilibrium of resultant forces and moments at the delamination crack front a multipoint constraint algorithm is incorporated which leads to unsymmetric stiffness matrices. The modified Hertzian contact law which accounts for permanent indentation is utilized to compute the contact force, and the time dependent equations are solved by Newmark's time integration algorithm. Parametric studies are performed in respect of location of delamination, angle of twist and rotational speed for centrally impacted graphite-epoxy composite cylindrical shells.

  11. Quasistatic Delamination of Sandwich-Like Kirchhoff-Love Plates

    Czech Academy of Sciences Publication Activity Database

    Freddi, L.; Roubíček, Tomáš; Zanini, Ch.

    2013-01-01

    Roč. 113, č. 2 (2013), s. 219-250 ISSN 0374-3535 R&D Projects: GA ČR GAP201/10/0357 Institutional research plan: CEZ:AV0Z20760514 Keywords : adhesive contact * delamination * mixed modes Subject RIV: BA - General Mathematics Impact factor: 1.043, year: 2013

  12. Utilization of Large Cohesive Interface Elements for Delamination Simulation

    DEFF Research Database (Denmark)

    Bak, Brian Lau Verndal; Lund, Erik

    2012-01-01

    This paper describes the difficulties of utilizing large interface elements in delamination simulation. Solutions to increase the size of applicable interface elements are described and cover numerical integration of the element and modifications of the cohesive law....

  13. Modeling Delamination of Interfacial Corner Cracks in Multilayered Structures

    DEFF Research Database (Denmark)

    Veluri, Badrinath (Badri); Jensen, Henrik Myhre

    2013-01-01

    Multilayered electronic components, typically of heterogeneous materials, delaminate under thermal and mechanical loading. A phenomenological model focused on modeling the shape of such interface cracks close to corners in layered interconnect structures for calculating the critical stress...

  14. Quasistatic delamination models for Kirchhoff-Love plates

    Czech Academy of Sciences Publication Activity Database

    Freddi, L.; Paroni, R.; Roubíček, Tomáš; Zanini, Ch.

    2011-01-01

    Roč. 91, č. 11 (2011), s. 845-865 ISSN 0044-2267 R&D Projects: GA ČR(CZ) GAP201/10/0357 Institutional research plan: CEZ:AV0Z20760514 Keywords : brittle delamination * adhesive contact * rate-independent processes Subject RIV: BA - General Mathematics Impact factor: 0.863, year: 2011 http://onlinelibrary.wiley.com/doi/10.1002/zamm.201000171/abstract

  15. Distributed fiber optic sensor-enhanced detection and prediction of shrinkage-induced delamination of ultra-high-performance concrete overlay

    Science.gov (United States)

    Bao, Yi; Valipour, Mahdi; Meng, Weina; Khayat, Kamal H.; Chen, Genda

    2017-08-01

    This study develops a delamination detection system for smart ultra-high-performance concrete (UHPC) overlays using a fully distributed fiber optic sensor. Three 450 mm (length) × 200 mm (width) × 25 mm (thickness) UHPC overlays were cast over an existing 200 mm thick concrete substrate. The initiation and propagation of delamination due to early-age shrinkage of the UHPC overlay were detected as sudden increases and their extension in spatial distribution of shrinkage-induced strains measured from the sensor based on pulse pre-pump Brillouin optical time domain analysis. The distributed sensor is demonstrated effective in detecting delamination openings from microns to hundreds of microns. A three-dimensional finite element model with experimental material properties is proposed to understand the complete delamination process measured from the distributed sensor. The model is validated using the distributed sensor data. The finite element model with cohesive elements for the overlay-substrate interface can predict the complete delamination process.

  16. Self-Diagnosis of Damage in Carbon Fiber Reinforced Composites Using Electrical Residual Resistance Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Ji Ho [KAERI, Daejeon (Korea, Republic of)

    2009-08-15

    The objective of this research was to develop a practical integrated approach using extracted features from electrical resistance measurements and coupled electromechanical models of damage, for in-situ damage detection and sensing in carbon fiber reinforced plastic(CFRP) composites. To achieve this objective, we introduced specific known damage (in terms of type, size, and location) into CFRP laminates and established quantitative relationships with the electrical resistance measurements. For processing of numerous measurement data, an autonomous data acquisition system was devised. We also established a specimen preparation procedure and a method for electrode setup. Coupon and panel CFRP laminate specimens with several known damage were tested. Coupon specimens with various sizes of artificial delaminations obtained by inserting Teflon film were manufactured and the resistance was measured. The measurement results showed that increase of delamination size led to increase of resistance implying that it is possible to sense the existence and size of delamination. A quasi-isotropic panel was manufactured and electrical resistance was measured. Then three different sizes of holes were drilled at a chosen location. The panel was prepared using the established procedures with six electrode connections on each side making a total of twenty-four electrodes. Vertical, horizontal, and diagonal pairs of electrodes were chosen and the resistance was measured. The measurement results showed the possibility of the established measurement system for an in-situ damage detection method for CFRP composite structures.

  17. Delaminating and restacking MgAl-layered double hydroxide monitored and characterized by a range of instrumental methods

    Science.gov (United States)

    Muráth, Szabolcs; Somosi, Zoltán; Tóth, Ildikó Y.; Tombácz, Etelka; Sipos, Pál; Pálinkó, István

    2017-07-01

    The delamination-restacking properties of MgAl-layered double hydroxide (MgAl-LDH) were studied in various solvents. The LDH samples were successfully delaminated in polar amides (formamide, N-methylformamide, N-methylacetamide). Usually, delamination was finalized by ultrasonic treatment. As rehydrating solutions, numerous Na-salts with single-, double- and triple-charged anions were used. Reconstruction was accomplished with anions of one or two negative charges, but triple-charged ones generally disrupted the rebuilding process, likely, because their salts with the metals of the LDH are very stable, and the thin layers can more readily transform to salts than the ordered materials. Samples and delamination-restacking processes were characterized by X-ray diffractometry (XRD), infrared spectroscopy (IR), dynamic light scattering (DLS), scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX).

  18. The ‘Sticky Elastica’: delamination blisters beyond small deformations

    KAUST Repository

    Wagner, Till J. W.; Vella, Dominic

    2013-01-01

    We consider the form of an elastic loop adhered to a rigid substrate: the 'Sticky Elastica'. In contrast to previous studies of the shape of delamination 'blisters', the theory developed accounts for deflections with large slope (i.e. geometrically

  19. The effect of cerium-based conversion treatment on the cathodic delamination and corrosion protection performance of carbon steel-fusion-bonded epoxy coating systems

    Energy Technology Data Exchange (ETDEWEB)

    Ramezanzadeh, B., E-mail: ramezanzadeh@aut.ac.ir [Department of Surface Coatings and Corrosion, Institute for Color Science and Technology (ICST), 16765-654, Tehran (Iran, Islamic Republic of); Rostami, M. [Department of Nanomaterials and Nanocoatings, Institute for Color Science and Technology (ICST), 16765-654, Tehran (Iran, Islamic Republic of)

    2017-01-15

    Highlights: • Steel surface was treated by Ce and acid phosphoric solutions. • Ce treatment considerably enhanced the surface energy and produce nanoscale roughness. • Ce treated samples showed enhanced adhesion to FBE coating. • Ce treatment of steel significantly reduced the FBE cathodic delamination rate. • Ce treated sample showed enhanced corrosion resistance. - Abstract: The effect of surface pre-treatment of pipe surface by green cerium compound and phosphoric acid solution on the fusion-bonded epoxy (FBE) coating performance was studied. The composition and surface morphology of the steel samples treated by acid and Ce solutions were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), equipped with energy dispersive spectroscopy (EDS). Also, the surface free energy was evaluated on these samples through contact angle measurements. In addition, the effect of Ce and acid washing procedures on the adhesion properties and corrosion protection performance of the FBE was examined by pull-off, salt spray and electrochemical impedance spectroscopy (EIS) tests. Results showed that compared to acid washing, the chemical treatment by Ce solution noticeably increased the surface free energy of steel, improved the adhesion properties of FBE, decreased the cathodic delamination rate of FBE, and enhanced the coating corrosion resistance compared to the acid washed samples.

  20. Hybrid diffusive/PVD treatments to improve the tribological resistance of Ti-6Al-4V.

    Science.gov (United States)

    Marin, E; Offoiach, R; Lanzutti, A; Regis, M; Fusi, S; Fedrizzi, L

    2014-01-01

    Titanium alloys are nowadays used for a wide range of biomedical applications thanks to their combination of high mechanical resistance, high corrosion resistance and biocompatibility. Nevertheless, the applicability of titanium alloys is sometimes limited due to their low microhardness and tribological resistance. Thus the titanium alloys cannot be successfully applied to prosthetic joint couplings. A wide range of surface treatments, in particular PVD coatings such as CrN and TiN, have been used in order to improve the tribological behaviour of titanium alloys. However, the low microhardness of the titanium substrate often results in coating failure due to cracks and delamination. For this reason, hybrid technologies based on diffusive treatments and subsequent PVD coatings may improve the overall coating resistance. In this work, conventional PVD coatings of CrN or TiCN, deposited on Titanium Grade 5, were characterized and then combined with a standard thermal diffusive nitriding treatment in order to improve the tribological resistance of the titanium alloys and avoid coating delamination. The different treatments were studied by means of scanning electron microscopy both on the sample surface and in cross-section. In-depth composition profiles were obtained using glow discharge optical emission spectrometry (GDOES) and localized energy dispersive X-ray diffraction on linear scan-lines. The microhardness and adhesion properties of the different treatments were evaluated using Vickers microhardness tests at different load conditions. The indentations were observed by means of SEM in order to evaluate delaminated areas and the crack's shape and density. The tribological behaviour of the different treatments was tested in dry conditions and in solution, in alternate pin-on-flat configuration, with a frequency of 0.5 Hz. After testing, the surface was investigated by means of stylus profilometry and SEM both on the surface and in cross-section. The standalone PVD

  1. [Reliability of HOMA-IR for evaluation of insulin resistance during perioperative period].

    Science.gov (United States)

    Fujino, Hiroko; Itoda, Shoko; Sako, Saori; Matsuo, Kazuki; Sakamoto, Eiji; Yokoyama, Takeshi

    2013-02-01

    Hyperglycemia due to increase in insulin resistance (IR) is often observed after surgery in spite of normal insulin secretion. To evaluate the degree of IR, the golden standard method is the normoglycemic hyperinsulinemic clamp technique (glucose clamp: GC). The GC using the artificial pancreas, STG-22 (Nikkiso, Tokyo, Japan), was established as a more reliable method, since it was evaluated during steady-state period under constant insulin infusion. Homeostasis model assessment insulin resistance (HOMA-IR), however, is frequently employed in daily practice because of its convenience. We, therefore, investigated the reliability of HOMA-IR in comparison with the glucose clamp using the STG-22. Eight healthy patients undergoing maxillofacial surgery were employed in this study after obtaining written informed consent. Their insulin resistance was evaluated by HOMA-IR and the GC using the STG-22 before and after surgery. HOMA-IR increased from 0.81 +/- 0.48 to 1.17 +/- 0.50, although there were no significant differences between before and after surgery. On the other hand, M-value by GC significantly decreased after surgery from 8.82 +/- 2.49 mg x kg(-1) x min(-1) to 3.84 +/- 0.79 mg x kg(-1) x min(-1) (P = 0.0003). In addition, no significant correlation was found between the values of HOMA-IR and the M-value by GC. HOMA-IR may not be reliable to evaluate IR for perioperative period.

  2. Structural health monitoring strategy for detection of interlaminar delamination in composite plates

    International Nuclear Information System (INIS)

    Quaegebeur, N; Micheau, P; Masson, P; Maslouhi, A

    2010-01-01

    In this paper, a structural health monitoring strategy for detecting interlaminar delamination in a carbon fiber reinforced polymer structure using Lamb waves is proposed. The delamination is simulated by inserting a Teflon tape between two transverse plies and the Lamb wave generation and measurement is enabled by using piezoceramic elements. The Lamb wave theoretical propagation and through thickness strain distribution are studied, in order to determine the optimal configuration of the final system in terms of mode and frequency selection, and piezoceramic sizing and spacing, for detection of cross-sectional delamination. Pitch and catch measurements are performed by comparing wave propagations for different frequencies and along damaged and undamaged paths of the structure, and the analysis of results is performed using the reassigned short time Fourier transform. It appears that in the low frequency range (below 300 kHz), the A0 mode is sensitive to the damage, while in the high frequency range, S1 and A1 modes are both very sensitive to the damage while the propagation of the S0 mode is not affected very much

  3. Identification of delamination interface in composite laminates using scattering characteristics of lamb wave: numerical and experimental studies

    Science.gov (United States)

    Singh, Rakesh Kumar; Ramadas, C.; Balachandra Shetty, P.; Satyanarayana, K. G.

    2017-04-01

    Considering the superior strength properties of polymer based composites over metallic materials, they are being used in primary structures of aircrafts. However, these polymeric materials are much more complex in behaviour due to their structural anisotropy along with existence of different materials unlike in metallic alloys. These pose challenge in flaw detection, residual strength determination and life of a structure with their high susceptibility to impact damage in the form of delaminations/disbonds or cracks. This reduces load-bearing capability and potentially leads to structural failure. With this background, this study presents a method to identify location of delamination interface along thickness of a laminate. Both numerical and experimental studies have been carried out with a view to identify the defect, on propagation, mode conversion and scattering characteristics of fundamental anti-symmetric Lamb mode (Ao) when it passed through a semi-infinite delamination. Further, the reflection and transmission scattering coefficients based on power and amplitude ratios of the scattered waves have been computed. The methodology was applied on numerically simulated delaminations to illustrate the efficacy of the method. Results showed that it could successfully identify delamination interface.

  4. Reliability-based load and resistance factor design for piping: an exploratory case study

    International Nuclear Information System (INIS)

    Gupta, Abhinav; Choi, Byounghoan

    2003-01-01

    This paper presents an exploratory case study on the application of Load and Resistance Factor Design (LRFD) approach to the Section III of ASME Boiler and Pressure Vessel code for piping design. The failure criterion for defining the performance function is considered as plastic instability. Presently used design equation is calibrated by evaluating the minimum reliability levels associated with it. If the target reliability in the LRFD approach is same as that evaluated for the presently used design equation, it is shown that the total safety factors for the two design equations are identical. It is observed that the load and resistance factors are not dependent upon the diameter to thickness ratio. A sensitivity analysis is also conducted to study the variations in the load and resistance factors due to changes in (a) coefficients of variation for pressure, moment, and ultimate stress, (b) ratio of mean design pressure to mean design moment, (c) distribution types used for characterizing the random variables, and (d) statistical correlation between random variables. It is observed that characterization of random variables by log-normal distribution is reasonable. Consideration of statistical correlation between the ultimate stress and section modulus gives higher values of the load factor for pressure but lower value for the moment than the corresponding values obtained by considering the variables to be uncorrelated. Since the effect of statistical correlation on the load and resistance factors is relatively insignificant for target reliability values of practical interest, the effect of correlated variables may be neglected

  5. THE INFLUENCE OF THE TOOL POINT ANGLE AND FEED RATE ON THE DELAMINATION AT DRILLING OF PRE-LAMINATED PARTICLEBOARD

    Directory of Open Access Journals (Sweden)

    Mihai ISPAS

    2015-12-01

    Full Text Available Pre-laminated particleboard is a wood based composite extensively used in the furniture industry. Drilling is the most common machining process which prepares the panels for joining using twist/helical drills in the absolute majority of cases. The point angle of the drill bit and the feed speed during drilling play a major role in gaining a good surface quality and minimizing the delamination tendency of the pre-laminated particleboard. The objective of this study was to measure and analyze the influence of the two above-mentioned factors on the processing quality, evaluated by de size of delaminations, both, at the entrance side and the exit side of the drill bit. To assess the defect, two parameters were used: the delamination factor and the effective area of delamination. The results showed that, in general, the combination of small point angle with low feed rate minimizes the delamination of pre-laminated particleboard panels at drilling.

  6. Time dependent response of low velocity impact induced composite conical shells under multiple delamination

    Science.gov (United States)

    Dey, Sudip; Karmakar, Amit

    2014-02-01

    This paper presents the time dependent response of multiple delaminated angle-ply composite pretwisted conical shells subjected to low velocity normal impact. The finite element formulation is based on Mindlin's theory incorporating rotary inertia and effects of transverse shear deformation. An eight-noded isoparametric plate bending element is employed to satisfy the compatibility of deformation and equilibrium of resultant forces and moments at the delamination crack front. A multipoint constraint algorithm is incorporated which leads to asymmetric stiffness matrices. The modified Hertzian contact law which accounts for permanent indentation is utilized to compute the contact force, and the time dependent equations are solved by Newmark's time integration algorithm. Parametric studies are conducted with respect to triggering parameters like laminate configuration, location of delamination, angle of twist, velocity of impactor, and impactor's displacement for centrally impacted shells.

  7. Laser micromachining of indium tin oxide films on polymer substrates by laser-induced delamination

    International Nuclear Information System (INIS)

    Willis, David A; Dreier, Adam L

    2009-01-01

    A Q-switched neodymium : yttrium-aluminium-garnet (Nd : YAG) laser was used to ablate indium tin oxide (ITO) thin films from polyethylene terephthalate substrates. Film damage and partial removal with no evidence of a melt zone was observed above 1.7 J cm -2 . Above the film removal threshold (3.3 J cm -2 ) the entire film thickness was removed without substrate damage, suggesting that ablation was a result of delamination of the film in the solid phase. Measurements of ablated fragment velocities near the ablation threshold were consistent with calculations of velocities caused by stress-induced delamination of the ITO film, except for a high velocity component at higher fluences. Nanosecond time-resolved shadowgraph photography revealed that the high velocity component was a shock wave induced by the rapid compression of ambient air when the film delaminated.

  8. Enhancement of delamination strength in Cu-stabilized coated conductor tapes through additional treatments under transverse tension at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Hyung Seop; Bautista, Zhierwinjay [Andong National University, Andong (Korea, Republic of); Moon, Seung Hyun; Lee, Jae Hun; Mean, Byoung Jean [SuNAM Co Ltd., Anseong (Korea, Republic of)

    2017-06-15

    In superconducting coil applications particularly in wet wound coils, coated conductor (CC) tapes are subjected to different type of stresses that could affect its electromechanical transport property. These include hoop stress acting along the length of the CC tape and the Lorentz force acting perpendicular to the CC tape’s surface. Since the latter is commonly associated with the delamination problem of multi-layered REBCO CC tapes, more understanding and attention on the delamination phenomena induced in the case of coil applications are needed. Difference on the coefficient of thermal expansion (CTE) of each constituent layer of the CC tape, the bobbin, and the impregnating materials is the main causes of delamination in CC tapes when subjected to thermal and mechanical cycling. In the design of degradation-free superconducting coils, therefore, characterization of the delamination behaviors including mechanism and strength in the multi-layered REBCO CC tapes becomes a critical issue. Various trials to increase the delamination strength by improving interface characteristics at interlayers have been performed. In this study, in order to investigate the influences of laser cleaning and Ag annealing treated at the substrate side surface, transverse tensile tests were conducted under different sample configurations using 4.5mm x 8 mm upper anvil. The mechanical delamination strength of differently processed CC samples was examined at room temperature (RT). As a result, the Sample 1 with the additional laser cleaning and Ag annealing processes and the Sample 2 with additional Ag annealing process only showed higher mechanical delamination strength as compared to the Sample 3 without such additional treatments. Sample 3 showed quite different behavior when the loading direction is to the substrate side where the delamination strength much lower as compared to other cases.

  9. Dynamic behavior of a rotating delaminated composite beam including rotary inertia and shear deformation effects

    Directory of Open Access Journals (Sweden)

    Ramazan-Ali Jafari-Talookolaei

    2015-09-01

    Full Text Available A finite element (FE model is developed to study the free vibration of a rotating laminated composite beam with a single delamination. The rotary inertia and shear deformation effects, as well as the bending–extension, bending–twist and extension–twist coupling terms are taken into account in the FE model. Comparison between the numerical results of the present model and the results published in the literature verifies the validity of the present model. Furthermore, the effects of various parameters, such as delamination size and location, fiber orientation, hub radius, material anisotropy and rotating speed, on the vibration of the beam are studied in detail. These results provide useful information in the study of the free vibration of rotating delaminated composite beams.

  10. Delamination and debonding failure of laminated composite T-joints

    NARCIS (Netherlands)

    Cui, H.

    2014-01-01

    Composites are increasingly being used in aerospace, automotive and other industries. The T-joint (also named stringer stiffened skin) is a typical connection, broadly used in thin-walled structures, such as the wing and fuselage of aircraft. This thesis presents the analysis of the delamination and

  11. Identification of Delamination in Concrete Slabs by SIBIE Procedure

    International Nuclear Information System (INIS)

    Yamada, M.; Yagi, Y.; Ohtsu, M.

    2017-01-01

    The Impact-Echo method is known as a non-destructive testing for concrete structures. The technique is based on the use of low-frequency elastic waves that propagate in concrete to determine the thickness and to detect internal flaws in concrete. The presence and locations of defects in concrete are estimated from identifying peak frequencies in the frequency spectra, which are responsible for the resonance due to time-of-flight from the defects. In practical applications, however, obtained spectra include so many peak frequencies that it is fairly difficult to identify the defects correctly. In order to improve the Impact-Echo method, Stack Imaging of spectral amplitudes Based on Impact-Echo (SIBIE) procedure is developed as an imaging technique applied to the Impact-Echo data, where defects in concrete are identified visually at the cross-section. In this study, the SIBIE procedure is applied to identify the delamination in a concrete slab. It is demonstrated that the delamination can be identified with reasonable accuracy. (paper)

  12. Delamination of neural crest cells requires transient and reversible Wnt inhibition mediated by Dact1/2.

    Science.gov (United States)

    Rabadán, M Angeles; Herrera, Antonio; Fanlo, Lucia; Usieto, Susana; Carmona-Fontaine, Carlos; Barriga, Elias H; Mayor, Roberto; Pons, Sebastián; Martí, Elisa

    2016-06-15

    Delamination of neural crest (NC) cells is a bona fide physiological model of epithelial-to-mesenchymal transition (EMT), a process that is influenced by Wnt/β-catenin signalling. Using two in vivo models, we show that Wnt/β-catenin signalling is transiently inhibited at the time of NC delamination. In attempting to define the mechanism underlying this inhibition, we found that the scaffold proteins Dact1 and Dact2, which are expressed in pre-migratory NC cells, are required for NC delamination in Xenopus and chick embryos, whereas they do not affect the motile properties of migratory NC cells. Dact1/2 inhibit Wnt/β-catenin signalling upstream of the transcriptional activity of T cell factor (TCF), which is required for EMT to proceed. Dact1/2 regulate the subcellular distribution of β-catenin, preventing β-catenin from acting as a transcriptional co-activator to TCF, yet without affecting its stability. Together, these data identify a novel yet important regulatory element that inhibits β-catenin signalling, which then affects NC delamination. © 2016. Published by The Company of Biologists Ltd.

  13. Analysis of a 'barb test' for measuring the mixed-mode delamination toughness of coatings

    International Nuclear Information System (INIS)

    Liu Yufu; Kagawa, Y.; Evans, A.G.

    2008-01-01

    The durability of thermal barrier coatings (TBCs) employed in most turbine engines is limited by delamination, both within the coating and at the coating-substrate interface. A test used for evaluating the mixed-mode toughness pertinent to such delaminations has been fully-analyzed by determining the steady-state energy release rate, the mode mixity and the critical length for buckling. An analytic solution based on beam theory establishes basic estimates and scaling relationships. Selected finite-element calculations have been used to affirm the fidelity of the results. The energy release rate attains steady-state, but the phase angle changes throughout because of a small (but significant) bending moment induced at the supports. The coating buckles at a critical delamination length, whereupon the energy release rate increases rapidly and violates steady state. The solutions are used to re-interpret measurements reported in the literature for an electron beam physically deposited TBC

  14. Study on drilling induced delamination of woven kenaf fiber reinforced epoxy composite using carbide drills

    Science.gov (United States)

    Suhaily, M.; Hassan, C. H. Che; Jaharah, A. G.; Azmi, H.; Afifah, M. A.; Khairusshima, M. K. Nor

    2018-04-01

    In this research study, it presents the influences of drilling parameters on the delamination factor during the drilling of woven kenaf fiber reinforced epoxy composite laminates when using the carbide drill bits. The purpose of this study is to investigate the influence of drilling parameters such as cutting speed, feed rate and drill sizes on the delamination produced when drilling woven kenaf reinforced epoxy composite using the non-coated carbide drill bits. The damage generated on the woven kenaf reinforced epoxy composite laminates were observed both at the entrance and exit surface during the drilling operation. The experiments were conducted according to the Box Behnken experimental designs. The results indicated that the drill diameter has a significant influence on the delamination when drilling the woven kenaf fiber reinforced epoxy composites.

  15. Characterization of Blistering and Delamination in Depleted Uranium Hohlraums

    Energy Technology Data Exchange (ETDEWEB)

    Biobaum, K. J. M.

    2013-03-01

    Blistering and delamination are the primary failure mechanisms during the processing of depleted uranium (DU) hohlraums. These hohlraums consist of a sputter-deposited DU layer sandwiched between two sputter-deposited layers of gold; a final thick gold layer is electrodeposited on the exterior. The hohlraum is deposited on a copper-coated aluminum mandrel; the Al and Cu are removed with chemical etching after the gold and DU layers are deposited. After the mandrel is removed, blistering and delamination are observed on the interiors of some hohlraums, particularly at the radius region. It is hypothesized that blisters are caused by pinholes in the copper and gold layers; etchant leaking through these holes reaches the DU layer and causes it to oxidize, resulting in a blister. Depending on the residual stress in the deposited layers, blistering can initiate larger-scale delamination at layer interfaces. Scanning electron microscopy indicates that inhomogeneities in the machined aluminum mandrel are replicated in the sputter-deposited copper layer. Furthermore, the Cu layer exhibits columnar growth with pinholes that likely allow etchant to come in contact with the gold layer. Any inhomogeneities or pinholes in this initial gold layer then become nucleation sites for blistering. Using a focused ion beam system to etch through the gold layer and extract a cross-sectional sample for transmission electron microscopy, amorphous, intermixed layers at the gold/DU interfaces are observed. Nanometer-sized bubbles in the sputtered and electrodeposited gold layers are also present. Characterization of the morphology and composition of the deposited layers is the first step in determining modifications to processing parameters, with the goal of attaining a significant improvement in hohlraum yield.

  16. An enriched cohesive zone model for delamination in brittle interfaces

    NARCIS (Netherlands)

    Samimi, M.; Dommelen, van J.A.W.; Geers, M.G.D.

    2009-01-01

    Application of standard cohesive zone models in a finite element framework to simulate delamination in brittle interfaces may trigger non-smooth load-displacement responses that lead to the failure of iterative solution procedures. This non-smoothness is an artifact of the discretization; and hence

  17. High acidity unilamellar zeolite MCM-56 and its pillared and delaminated derivatives.

    Science.gov (United States)

    Gil, Barbara; Makowski, Wacław; Marszalek, Bartosz; Roth, Wieslaw J; Kubu, Martin; Čejka, Jiři; Olejniczak, Zbigniew

    2014-07-21

    The unilamellar form of zeolite MWW, MCM-56, which is obtained by direct hydrothermal synthesis has been studied with regard to acidity and porosity in its original and post-synthesis modified pillared and delaminated forms. The acidity measured by FTIR was found to be only slightly lower than the highly active 3-D MWW forms, MCM-22 and MCM-49. Pivalonitrile adsorption, which is a measure of spatial openness, showed 50% accessibility vs. MCM-22/49. It highlights the potential of MCM-56 as a layered material with increased access to acid sites because it does not entail laborious post-synthesis modification. Swelling, pillaring and delamination of MCM-56 are facile but result in a reduction in the number of Brønsted acid sites (BAS) while increasing accessibility to pivalonitrile. The delamination procedure involving sonication and acidification of the highly basic mother liquor produces the most visible increase in surface area and access to all BAS. The accompanying doubling of the solid yield and the decrease in absolute number of BAS suggest significant precipitation of dissolved silica generated during swelling and sonication in high pH medium. The viability of separating surfactant covered layers upon sonication with the consequence of exposing hydrophobic hydrocarbon tails to aqueous environment is addressed.

  18. Floating Node Method and Virtual Crack Closure Technique for Modeling Matrix Cracking-Delamination Migration

    Science.gov (United States)

    DeCarvalho, Nelson V.; Chen, B. Y.; Pinho, Silvestre T.; Baiz, P. M.; Ratcliffe, James G.; Tay, T. E.

    2013-01-01

    A novel approach is proposed for high-fidelity modeling of progressive damage and failure in composite materials that combines the Floating Node Method (FNM) and the Virtual Crack Closure Technique (VCCT) to represent multiple interacting failure mechanisms in a mesh-independent fashion. In this study, the approach is applied to the modeling of delamination migration in cross-ply tape laminates. Delamination, matrix cracking, and migration are all modeled using fracture mechanics based failure and migration criteria. The methodology proposed shows very good qualitative and quantitative agreement with experiments.

  19. Potential-Induced Degradation-Delamination Mode in Crystalline Silicon Modules: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Hacke, Peter L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kempe, Michael D [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Wohlgemuth, John [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Li, Jichao [SunPower Corporation; Shen, Yu-Chen [SunPower Corporation

    2018-03-21

    A test sequence producing potential-induced degradation-delamination (PID-d) in crystalline silicon modules has been tested and found comparable under visual inspection to cell/encapsulant delamination seen in some fielded modules. Four commercial modules were put through this sequence, 85 degrees C, 85%, 1000 h damp heat, followed by an intensive PID stress sequence of 72 degrees C, 95% RH, and -1000 V, with the module face grounded using a metal foil. The 60 cell c-Si modules exhibiting the highest current transfer (4.4 center dot 10-4 A) exhibited PID-d at the first inspection after 156 h of PID stress. Effects promoting PID-d are reduced adhesion caused by damp heat, sodium migration further reducing adhesion to the cells, and gaseous products of electrochemical reactions driven by the applied system voltage. A new work item proposal for an IEC test standard to evaluate for PID-d is anticipated.

  20. Development of reliability-based load and resistance factor design methods for piping

    International Nuclear Information System (INIS)

    Ayyub, Bilal M.; Hill, Ralph S. III; Balkey, Kenneth R.

    2003-01-01

    Current American Society of Mechanical Engineers (ASME) nuclear codes and standards rely primarily on deterministic and mechanistic approaches to design. The American Institute of Steel Construction and the American Concrete Institute, among other organizations, have incorporated probabilistic methodologies into their design codes. ASME nuclear codes and standards could benefit from developing a probabilistic, reliability-based, design methodology. This paper provides a plan to develop the technical basis for reliability-based, load and resistance factor design of ASME Section III, Class 2/3 piping for primary loading, i.e., pressure, deadweight and seismic. The plan provides a proof of concept in that LRFD can be used in the design of piping, and could achieve consistent reliability levels. Also, the results from future projects in this area could form the basis for code cases, and additional research for piping secondary loads. (author)

  1. Role of Delamination in Zeolite-Catalyzed Aromatic Alkylation: UCB-3 versus 3-D Al-SSZ-70

    Energy Technology Data Exchange (ETDEWEB)

    Runnebaum, Ron C.; Ouyang, Xiaoying; Edsinga, Jeffrey A.; Rea, Thomas; Arslan, Ilke; Hwang, Son-Jong; Zones, Stacey I.; Katz, Alexander

    2014-07-03

    Delaminated zeolite UCB-3 exhibits 2.4-fold greater catalytic activity relative to its three-dimensional (3D) zeolite counterpart, Al-SSZ-70, and 2.0-fold greater activity (per catalyst mass) when compared with industrial catalyst MCM-22, for the alkylation of toluene with propylene at 523 K. The former increase is nearly equal to the observed relative increase in external surface area and acid sites upon delamination. However, at 423 K for the same reaction, UCB-3 exhibits a 3.5-fold greater catalytic activity relative to 3D Al-SSZ-70. The higher relative rate enhancement for the delaminated material at lower temperature can be elucidated on the basis of increased contributions from internal acid sites. Evidence of possible contributions from such acid sites is obtained by performing catalysis after silanation treatment, which demonstrates that although virtually all catalysis in MCM-22 occurs on the external surface, catalysis also occurs on internal sites for 3D Al-SSZ-70. The additional observed enhancement at low temperatures can therefore be rationalized by greater access to internal active sites as a result of sheet breakage during delamination. Such breakage leads to shorter characteristic internal diffusion paths and was visualized using TEM comparisons of UCB-3 and 3D Al-SSZ-70.

  2. Laser Structuring of Thin Layers for Flexible Electronics by a Shock Wave-induced Delamination Process

    Science.gov (United States)

    Lorenz, Pierre; Ehrhardt, Martin; Zimmer, Klaus

    The defect-free laser-assisted structuring of thin films on flexible substrates is a challenge for laser methods. However, solving this problem exhibits an outstanding potential for a pioneering development of flexible electronics. Thereby, the laser-assisted delamination method has a great application potential. At the delamination process: the localized removal of the layer is induced by a shock wave which is produced by a laser ablation process on the rear side of the substrate. In this study, the thin-film patterning process is investigated for different polymer substrates dependent on the material and laser parameters using a KrF excimer laser. The resultant structures were studied by optical microscopy and white light interferometry (WLI). The delamination process was tested at different samples (indium tin oxide (ITO) on polyethylene terephthalate (PET), epoxy-based negative photoresist (SU8) on polyimide (PI) and indium tin oxide/copper indium gallium selenide/molybdenum (ITO/CIGS/Mo) on PI.

  3. Reliability of Strength Testing using the Advanced Resistive Exercise Device and Free Weights

    Science.gov (United States)

    English, Kirk L.; Loehr, James A.; Laughlin, Mitzi A.; Lee, Stuart M. C.; Hagan, R. Donald

    2008-01-01

    The Advanced Resistive Exercise Device (ARED) was developed for use on the International Space Station as a countermeasure against muscle atrophy and decreased strength. This investigation examined the reliability of one-repetition maximum (1RM) strength testing using ARED and traditional free weight (FW) exercise. Methods: Six males (180.8 +/- 4.3 cm, 83.6 +/- 6.4 kg, 36 +/- 8 y, mean +/- SD) who had not engaged in resistive exercise for at least six months volunteered to participate in this project. Subjects completed four 1RM testing sessions each for FW and ARED (eight total sessions) using a balanced, randomized, crossover design. All testing using one device was completed before progressing to the other. During each session, 1RM was measured for the squat, heel raise, and deadlift exercises. Generalizability (G) and intraclass correlation coefficients (ICC) were calculated for each exercise on each device and were used to predict the number of sessions needed to obtain a reliable 1RM measurement (G . 0.90). Interclass reliability coefficients and Pearson's correlation coefficients (R) also were calculated for the highest 1RM value (1RM9sub peak)) obtained for each exercise on each device to quantify 1RM relationships between devices.

  4. Mode I fatigue delamination growth in composite laminates with fibre bridging

    NARCIS (Netherlands)

    Yao, L.

    2015-01-01

    Advanced composite materials have been commonly used in aerospace engineering, because of their good mechanical properties and attractive potential for creating lightweight structures. Susceptibility to delamination is one of the most important issues in the applications of these materials. This

  5. Zr-doped TiO{sub 2} supported on delaminated clay materials for solar photocatalytic treatment of emerging pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Belver, C., E-mail: carolina.belver@uam.es; Bedia, J.; Rodriguez, J.J.

    2017-01-15

    Highlights: • Novel Zr-doped TiO{sub 2} delaminated clay materials were prepared by a sol-gel process. • Zr is incorporated into the anatase lattice. • Zr-TiO{sub 2} nanoparticles are homogenously distributed over the delaminated clay. • Zr doping enhances the photoactivity by reducing the band gap. • Degradation rates were favored at low concentrations and high radiation intensities. - Abstract: Solar light-active Zr-doped TiO{sub 2} nanoparticles were successfully immobilized on delaminated clay materials by a one-step sol-gel route. Fixing the amount of TiO{sub 2} at 65 wt.%, this work studies the influence of Zr loading (up to 2%) on the photocatalytic activity of the resulting Zr-doped TiO{sub 2}/clay materials. The structural characterization demonstrates that all samples were formed by a delaminated clay with nanostructured anatase assembled on its surface. The Zr dopant was successfully incorporated into the anatase lattice, resulting in a slight deformation of the anatase crystal and the reduction of the band gap. These materials exhibit high surface area with a disordered mesoporous structure formed by TiO{sub 2} particles (15–20 nm) supported on a delaminated clay. They were tested in the solar photodegradation of antipyrine, usually used as an analgesic drug and selected as an example of emerging pollutant. High degradation rates have been obtained at low antipyrine concentrations and high solar irradiation intensities with the Zr-doped TiO{sub 2}/clay catalyst, more effective than the undoped one. This work demonstrates the potential application of the synthesis method for preparing novel and efficient solar-light photocatalysts based on metal-doped anatase and a delaminated clay.

  6. Highly uniform and reliable resistive switching characteristics of a Ni/WOx/p+-Si memory device

    Science.gov (United States)

    Kim, Tae-Hyeon; Kim, Sungjun; Kim, Hyungjin; Kim, Min-Hwi; Bang, Suhyun; Cho, Seongjae; Park, Byung-Gook

    2018-02-01

    In this paper, we investigate the resistive switching behavior of a bipolar resistive random-access memory (RRAM) in a Ni/WOx/p+-Si RRAM with CMOS compatibility. Highly unifrom and reliable bipolar resistive switching characteristics are observed by a DC voltage sweeping and its switching mechanism can be explained by SCLC model. As a result, the possibility of metal-insulator-silicon (MIS) structural WOx-based RRAM's application to Si-based 1D (diode)-1R (RRAM) or 1T (transistor)-1R (RRAM) structure is demonstrated.

  7. Microwave detection of delaminations between fiber reinforced polymer (FRP) composite and hardened cement paste

    Science.gov (United States)

    Hughes, D.; Kazemi, M.; Marler, K.; Zoughi, R.; Myers, J.; Nanni, A.

    2002-05-01

    Fiber reinforced polymer (FRP) composites are increasingly being used for the rehabilitation of concrete structures. Detection and characterization of delaminations between an FRP composite and a concrete surface are of paramount importance. Consequently, the development of a one sided, non-contact, real time and rapid nondestructive testing (NDT) technique for this purpose is of great interest. Near-field microwave NDT techniques, using open-ended rectangular waveguide probes, have shown great potential for detecting delaminations in layered composite structures such as these. The results of some theoretical and experimental investigations on a specially prepared cement paste specimen are presented here.

  8. Reliability of the MicroScan WalkAway PC21 panel in identifying and detecting oxacillin resistance in clinical coagulase-negative staphylococci strains.

    Science.gov (United States)

    Olendzki, A N; Barros, E M; Laport, M S; Dos Santos, K R N; Giambiagi-Demarval, M

    2014-01-01

    The purpose of this study was to determine the reliability of the MicroScan WalkAway PosCombo21 (PC21) system for the identification of coagulase-negative staphylococci (CNS) strains and the detection of oxacillin resistance. Using molecular and phenotypic methods, 196 clinical strains were evaluated. The automated system demonstrated 100 % reliability for the identification of the clinical strains Staphylococcus haemolyticus, Staphylococcus hominis and Staphylococcus cohnii; 98.03 % reliability for the identification of Staphylococcus epidermidis; 70 % reliability for the identification of Staphylococcus lugdunensis; 40 % reliability for the identification of Staphylococcus warneri; and 28.57 % reliability for the identification of Staphylococcus capitis, but no reliability for the identification of Staphylococcus auricularis, Staphylococcus simulans and Staphylococcus xylosus. We concluded that the automated system provides accurate results for the more common CNS species but often fails to accurately identify less prevalent species. For the detection of oxacillin resistance, the automated system showed 100 % specificity and 90.22 % sensitivity. Thus, the PC21 panel detects oxacillin-resistant strains, but is limited by the heteroresistance that is observed when using most phenotypic methods.

  9. 3D finite element analysis of stress distributions and strain energy release rates for adhesive bonded flat composite lap shear joints having pre-existing delaminations

    Energy Technology Data Exchange (ETDEWEB)

    Parida, S. K.; Pradhan, A. K. [Indian Institute of Technology, Bhubaneswar (India)

    2014-02-15

    The rate of propagation of embedded delamination in the strap adherend of lap shear joint (LSJ) made of carbon/epoxy composites has been evaluated employing three-dimensional non-linear finite elements. The delamination has been presumed to pre-exist in the thin resin layer between the first and second plies of the strap adherend. The inter-laminar peel and shear stress distributions have been studied in details and are seen to be predominantly three-dimensional in nature. The components of strain energy release rate (SERR) corresponding to the opening, sliding and cross sliding modes of delamination are significantly different at the two fronts of the embedded delamination. The sequential release of multi-point constraint (MPC) finite elements in the vicinity of the delamination fronts enables to simulate the growth of the delamination at either ends. This simulation procedure can be utilized effectively for evaluation of the status of the structural integrity of the bonded joints.

  10. The concept of fatigue fracture toughness in fatigue delamination growth behavior

    NARCIS (Netherlands)

    Yao, L.; Alderliesten, R.C.; Benedictus, R.

    2015-01-01

    This paper provides a study on mode I fatigue delamination growth in composite laminates using energy principles. Experimental data has been obtained from fatigue tests conducted on Double Cantilever Beam (DCB) specimens at various stress ratios. A concept of fatigue fracture toughness is proposed

  11. Cracking and delamination of vapor-deposited tantalum films

    International Nuclear Information System (INIS)

    Fisher, R.M.; Duan, J.Z.; Liu, J.B.

    1990-01-01

    This paper reports on tantalum films which begin to crack and spall during vapor deposition on glass at a thickness of 180 nm. Islands and ribbons, 10 - 30 μm in size, delaminate by crack growth along the Ta/glass interface for several μm after which the crack penetrates into the glass to a depth of 0.5 - 1 μm and complete spalling occurs. X-ray diffraction showed that about 50% of the original bct, β-tantalum, phase had transformed to the bcc α-Ta phase. When Ta was deposited on glass that was first covered with 52 nm of copper, spalling was observed to begin at a thickness of 105 nm. In this case, the film first cracks and then peels along the Cu/glass interface and curls into scrolls indicating the presence of a small stress gradient. X-ray diffraction of the as-deposited film, and electron diffraction of ion-milled flakes, showed that the Ta films deposited on Cu-coated glass almost completely transform to bcc α-Ta. The critical thickness for delamination along the Cu/glass interface is about 1/2 that for cracking in the glass substrate when an intermediate layer of Cu is not present. All of the above findings are in good agreement with previous observations on Cr films

  12. Delamination Mechanisms of Thermal and Environmental Barrier Coatings on SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Choi, Sung R.; Lee, Kang N.; Miller, Robert A.

    2003-01-01

    Advanced ceramic thermal harrier coatings will play an increasingly important role In future gas turbine engines because of their ability to effectively protect the engine components and further raise engine temperatures. However, the coating durability issue remains a major concern with the ever-increasing temperature requirements. In this paper, thermal cyclic response and delamination failure modes of a ZrO2-8wt%Y2O3 and mullite/BSAS thermaVenvironmenta1 barrier coating system on SiC/SiC ceramic matrix composites were investigated using a laser high-heat-flux technique. The coating degradation and delamination processes were monitored in real time by measuring coating apparent conductivity changes during the cyclic tests under realistic engine temperature and stress gradients, utilizing the fact that delamination cracking causes an apparent decrease in the measured thermal conductivity. The ceramic coating crack initiation and propagation driving forces under the cyclic thermal loads, in conjunction with the mechanical testing results, will be discussed.

  13. The Influence of Resistance Training Experience on the Between-Day Reliability of Commonly Used Strength Measures in Male Youth Athletes.

    Science.gov (United States)

    Weakley, Jonathon J S; Till, Kevin; Darrall-Jones, Joshua; Roe, Gregory A B; Phibbs, Padraic J; Read, Dale B; Jones, Ben L

    2017-07-01

    Weakley, JJS, Till, K, Darrall-Jones, J, Roe, GAB, Phibbs, PJ, Read, DB, and Jones, BL. The influence of resistance training experience on the between-day reliability of commonly used strength measures in male youth athletes. J Strength Cond Res 31(7): 2005-2010, 2017-The purpose of this study was to determine the between-day reliability of commonly used strength measures in male youth athletes while considering resistance training experience. Data were collected on 25 male athletes over 2 testing sessions, with 72 hours rest between, for the 3 repetition maximum (3RM) front squat, chin-up, and bench press. Subjects were initially categorized by resistance training experience (inexperienced; 6-12 months, experienced; >2 years). The assessment of the between-day reliability (coefficient of variation [CV%]) showed that the front squat (experienced: 2.90%; inexperienced: 1.90%), chin-up (experienced: 1.70%; inexperienced: 1.90%), and bench press (experienced: 4.50%; inexperienced: 2.40%) were all reliable measures of strength in both groups. Comparison between groups for the error of measurement for each exercise showed trivial differences. When both groups were combined, the CV% for the front squat, bench press, and chin-up were 2.50, 1.80, and 3.70%, respectively. This study provides scientists and practitioners with the between-day reliability reference data to determine real and practical changes for strength in male youth athletes with different resistance training experience. Furthermore, this study demonstrates that 3RM front squat, chin-up, and bench press are reliable exercises to quantify strength in male youth athletes.

  14. Delamination Assessment Tool for Spacecraft Composite Structures

    Science.gov (United States)

    Portela, Pedro; Preller, Fabian; Wittke, Henrik; Sinnema, Gerben; Camanho, Pedro; Turon, Albert

    2012-07-01

    Fortunately only few cases are known where failure of spacecraft structures due to undetected damage has resulted in a loss of spacecraft and launcher mission. However, several problems related to damage tolerance and in particular delamination of composite materials have been encountered during structure development of various ESA projects and qualification testing. To avoid such costly failures during development, launch or service of spacecraft, launcher and reusable launch vehicles structures a comprehensive damage tolerance verification approach is needed. In 2009, the European Space Agency (ESA) initiated an activity called “Delamination Assessment Tool” which is led by the Portuguese company HPS Lda and includes academic and industrial partners. The goal of this study is the development of a comprehensive damage tolerance verification approach for launcher and reusable launch vehicles (RLV) structures, addressing analytical and numerical methodologies, material-, subcomponent- and component testing, as well as non-destructive inspection. The study includes a comprehensive review of current industrial damage tolerance practice resulting from ECSS and NASA standards, the development of new Best Practice Guidelines for analysis, test and inspection methods and the validation of these with a real industrial case study. The paper describes the main findings of this activity so far and presents a first iteration of a Damage Tolerance Verification Approach, which includes the introduction of novel analytical and numerical tools at an industrial level. This new approach is being put to the test using real industrial case studies provided by the industrial partners, MT Aerospace, RUAG Space and INVENT GmbH

  15. Contribution to interplay between a delamination test and a sensory analysis of mid-range lipsticks.

    Science.gov (United States)

    Richard, C; Tillé-Salmon, B; Mofid, Y

    2016-02-01

    Lipstick is currently one of the most sold products of cosmetics industry, and the competition between the various manufacturers is significant. Customers mainly seek products with high spreadability, especially long-lasting or long wear on the lips. Evaluation tests of cosmetics are usually performed by sensory analysis. This can then represent a considerable cost. The object of this study was to develop a fast and simple test of delamination (objective method with calibrated instruments) and to interplay the obtained results with those of a discriminative sensory analysis (subjective method) in order to show the relevance of the instrumental test. Three mid-range lipsticks were randomly chosen and were tested. They were made of compositions as described by the International Nomenclature of Cosmetic Ingredients (INCI). Instrumental characterization was performed by texture profile analysis and by a special delamination test. The sensory analysis was voluntarily conducted with an untrained panel as blind test to confirm or reverse the possible interplay. The two approaches or methods gave the same type of classification. The high-fat lipstick had the worst behaviour with the delamination test and the worst notation of the intensity of descriptors with the sensory analysis. There is a high correlation between the sensory analysis and the instrumental measurements in this study. The delamination test carried out should permit to quickly determine the lasting (screening test) and in consequence optimize the basic formula of lipsticks. © 2015 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  16. Study on Fatigue Performance of Composite Bolted Joints with Bolt-Hole Delamination

    Science.gov (United States)

    Liu, M. J.; Yu, S.; Zhao, Q. Y.

    2018-03-01

    Fatigue performance of composite structure with imperfections is a challenging subject at present. Based on cohesive zone method and multi-continuum theory, delamination evolution response and fatigue life prediction of a 3D composite single-lap joint with a bolt-hole have been investigated through computer codes Abaqus and Fe-safe. Results from the comparison of a perfect composite bolted joint with another defect one indicates that a relatively small delamination damage around the bolt hole brings about significant degradation of local material performance. More notably, fatigue life of stress concentration region of composite bolted joints is highly sensitive to external loads, as an increase of 67% cyclic load amplitude leads to an decrease of 99.5% local fatigue life in this study. However, the numerical strategy for solving composite fatigue problems is meaningful to engineering works.

  17. DETECTION OF DELAMINATION IN A COMPOSITE PLATE BY SEM

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A numerical method of integration of Green's functi ons of strip element method (SEM) is proposed. The response of ultrasonic sourc e generated by a transducer on the surface of a multi-ply composite plate conta ining a delamination is analyzed by the use of SEM. The numerical results show that the scanning features of the ultrasonic waves may be used to identify the d elamination inside the composite plate .

  18. Shadowgraph studies of laser-assisted non-thermal structuring of thin layers on flexible substrates by shock-wave-induced delamination processes

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, Pierre, E-mail: pierre.lorenz@iom-leipzig.de [Leibniz-Institut für Oberflächenmodifizierung e. V., Permoserstraße 15, 04318 Leipzig (Germany); Smausz, Tomi [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary); MTA-SZTE Research Group on Photoacoustic Spectroscopy, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary); Csizmadia, Tamas [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary); Ehrhardt, Martin; Zimmer, Klaus [Leibniz-Institut für Oberflächenmodifizierung e. V., Permoserstraße 15, 04318 Leipzig (Germany); Hopp, Bela [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary)

    2015-05-01

    Highlights: • The shock-wave-induced film delamination (SWIFD) is a laser patterning process. • The SWIFD process of CIGS solar cells was studied by shadowgraph measurements. • The study presented that SWIFD allows the structuring of CIGS solar cells. • The dynamics of the delamination process was analyzed. - Abstract: The laser-assisted microstructuring of thin films especially for electronic applications without damaging the layers or the substrates is a challenge for the laser micromachining techniques. The laser-induced thin-film patterning by ablation of the polymer substrate at the rear side that is called ‘SWIFD’ – shock-wave-induced film delamination patterning has been demonstrated. This study focuses on the temporal sequence of processes that characterize the mechanism of this SWIFD process on a copper indium gallium selenide (CIGS) solar cell stacks on polyimide. For this purpose high-speed shadowgraph experiments were performed in a pump probe experimental set-up using a KrF excimer laser for ablating the rear side of the polyimide substrate and measuring the shock wave generation at laser ablation of the polymer substrate as well as the thin-film delamination. The morphology and size of the thin-film structures were studied by scanning electron microscopy (SEM). Furthermore, the composition after the laser treatment was analyzed by energy dispersive X-ray (EDX) spectroscopy. The shadowgraph experiments allow the time-dependent identification and evaluation of the shock wave formation, substrate bending, and delamination of the thin film in dependence on the laser parameters. These results will contribute to improve the physical understanding of the laser-induced delamination effect for thin-film patterning.

  19. Delamination measurement of a laminates composite panel due to hole punching based on the focus variation technique

    Science.gov (United States)

    Abdullah, A. B.; Zain, M. S. M.; Abdullah, M. S.; Samad, Z.

    2017-07-01

    Structural materials, such as composite panels, must be assembled, and such panels are typically constructed via the insertion of a fastener through a drilled hole. The main problem encountered in drilling is delamination, which affects assembly strength. The cost of drilling is also high because of the severe wear on drill bits. The main goal of this research is to develop a new punching method as an alternative to drilling during hole preparation. In this study, the main objective is to investigate the effect of different puncher profiles on the quality of holes punched into carbon fiber reinforcement polymer (CFRP) composite panels. Six types of puncher profiles were fabricated with minimum die clearance (1%), and two quality aspects, namely, incomplete shearing and delamination factor, were measured. The conical puncher incurred the least defects in terms of delamination and yielded an acceptable amount of incomplete shearing in comparison with the other punchers.

  20. Surface modified MXene Ti_3C_2 multilayers by aryl diazonium salts leading to large-scale delamination

    International Nuclear Information System (INIS)

    Wang, Hongbing; Zhang, Jianfeng; Wu, Yuping; Huang, Huajie; Li, Gaiye; Zhang, Xin; Wang, Zhuyin

    2016-01-01

    Highlights: • A novel and simple method to delaminate MXene Ti_3C_2 multilayers. • Surface modification using aryl diazonium salts induced swelling that conversely weakened the bonds between MXene layers. • The grafting of phenylsulfonic acid groups on MXene surfaces resulted in excellent water dispersibility. - Abstract: Herein we report a simple and facile method to delaminate MXene Ti_3C_2 multilayers by the assistance of surface modification using aryl diazonium salts. The basic strategy involved the preparation of layered MAX Ti_3AlC_2 and the exfoliation of Ti_3AlC_2 into Ti_3C_2 multilayers, followed by Na"+ intercalation and surface modification using sulfanilic acid diazonium salts. The resulting chemically grafted Ti_3C_2 flakes were characterized by Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) to confirm the presence of the surface organic species. Ultraviolet-visible spectroscopy revealed that surface-modified MXene Ti_3C_2 sheets disperse well in water and the solutions obey Lambert–Beer’s law. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to demonstrate the morphology and structure of delaminating MXene Ti_3C_2 flakes. The results indicated that chemical modification for MXene multilayers by aryl diazonium salts induced swelling that conversely weakened the bonds between MX layers, hence leading to large-scale delamination of multilayered MXene Ti_3C_2via mild sonication. Advantages of the present approach rely not only on the simplicity and efficiency of the delamination procedure but also on the grafting of aryl groups to MXene surfaces, highly suitable for further applications of the newly discovered two-dimensional materials.

  1. A negative modulatory role for rho and rho-associated kinase signaling in delamination of neural crest cells

    Directory of Open Access Journals (Sweden)

    Kalcheim Chaya

    2008-10-01

    Full Text Available Abstract Background Neural crest progenitors arise as epithelial cells and then undergo a process of epithelial to mesenchymal transition that precedes the generation of cellular motility and subsequent migration. We aim at understanding the underlying molecular network. Along this line, possible roles of Rho GTPases that act as molecular switches to control a variety of signal transduction pathways remain virtually unexplored, as are putative interactions between Rho proteins and additional known components of this cascade. Results We investigated the role of Rho/Rock signaling in neural crest delamination. Active RhoA and RhoB are expressed in the membrane of epithelial progenitors and are downregulated upon delamination. In vivo loss-of-function of RhoA or RhoB or of overall Rho signaling by C3 transferase enhanced and/or triggered premature crest delamination yet had no effect on cell specification. Consistently, treatment of explanted neural primordia with membrane-permeable C3 or with the Rock inhibitor Y27632 both accelerated and enhanced crest emigration without affecting cell proliferation. These treatments altered neural crest morphology by reducing stress fibers, focal adhesions and downregulating membrane-bound N-cadherin. Reciprocally, activation of endogenous Rho by lysophosphatidic acid inhibited emigration while enhancing the above. Since delamination is triggered by BMP and requires G1/S transition, we examined their relationship with Rho. Blocking Rho/Rock function rescued crest emigration upon treatment with noggin or with the G1/S inhibitor mimosine. In the latter condition, cells emigrated while arrested at G1. Conversely, BMP4 was unable to rescue cell emigration when endogenous Rho activity was enhanced by lysophosphatidic acid. Conclusion Rho-GTPases, through Rock, act downstream of BMP and of G1/S transition to negatively regulate crest delamination by modifying cytoskeleton assembly and intercellular adhesion.

  2. Selective role of bainitic lath boundary in influencing slip systems and consequent deformation mechanisms and delamination in high-strength low-alloy steel

    Science.gov (United States)

    Liu, S.; Li, X.; Guo, H.; Yang, S.; Wang, X.; Shang, C.; Misra, R. D. K.

    2018-04-01

    We elucidate here the deformation behaviour and delamination phenomenon in a high-strength low-alloy bainitic steel, in terms of microstructure, texture and stress evolution during deformation via in situ electron back-scattered diffraction and electron microscopy. Furthermore, the selective role of bainitic lath boundary on slip systems was studied in terms of dislocation pile-up and grain boundary energy models. During tensile deformation, the texture evolution was concentrated at {1 1 0} and the laths were turn parallel to loading direction. The determining role of lath on the deformation behaviour is governed by length/thickness (l/t) ratio. When l/t > 28, the strain accommodates along the bainite lath rather than along the normal direction. The delamination crack initiated normal to (0 1 1) plane, and become inclined to (0 1 1) plane with continued strain along (0 1 1) plane and lath plane. This indicated that the delamination is not brittle process but plastic process. The lack of dimples at the delaminated surface is because of lack of strain normal to the direction of lath. The delaminated (0 1 1) planes were associated with cleavage along the (1 0 0) plane.

  3. Predictions of Poisson's ratio in cross-ply laminates containing matrix cracks and delaminations

    Science.gov (United States)

    Harris, Charles E.; Allen, David H.; Nottorf, Eric W.

    1989-01-01

    A damage-dependent constitutive model for laminated composites has been developed for the combined damage modes of matrix cracks and delaminations. The model is based on the concept of continuum damage mechanics and uses second-order tensor valued internal state variables to represent each mode of damage. The internal state variables are defined as the local volume average of the relative crack face displacements. Since the local volume for delaminations is specified at the laminate level, the constitutive model takes the form of laminate analysis equations modified by the internal state variables. Model implementation is demonstrated for the laminate engineering modulus E(x) and Poisson's ratio nu(xy) of quasi-isotropic and cross-ply laminates. The model predictions are in close agreement to experimental results obtained for graphite/epoxy laminates.

  4. Failure Predictions of Out-of-Autoclave Sandwich Joints with Delaminations Under Flexure Loads

    Science.gov (United States)

    Nordendale, Nikolas A.; Goyal, Vinay K.; Lundgren, Eric C.; Patel, Dhruv N.; Farrokh, Babak; Jones, Justin; Fischetti, Grace; Segal, Kenneth N.

    2015-01-01

    An analysis and a test program was conducted to investigate the damage tolerance of composite sandwich joints. The joints contained a single circular delamination between the face-sheet and the doubler. The coupons were fabricated through out-of-autoclave (OOA) processes, a technology NASA is investigating for joining large composite sections. The four-point bend flexure test was used to induce compression loading into the side of the joint where the delamination was placed. The compression side was chosen since it tends to be one of the most critical loads in launch vehicles. Autoclave cure was used to manufacture the composite sandwich sections, while the doubler was co-bonded onto the sandwich face-sheet using an OOA process after sandwich panels were cured. A building block approach was adopted to characterize the mechanical properties of the joint material, including the fracture toughness between the doubler and face-sheet. Twelve four-point-bend samples were tested, six in the sandwich core ribbon orientation and six in sandwich core cross-ribbon direction. Analysis predicted failure initiation and propagation at the pre-delaminated location, consistent with experimental observations. A building block approach using fracture analyses methods predicted failure loads in close agreement with tests. This investigation demonstrated a small strength reduction due to a flaw of significant size compared to the width of the sample. Therefore, concerns of bonding an OOA material to an in-autoclave material was mitigated for the geometries, materials, and load configurations considered.

  5. Buckle initiation and delamination of patterned ITO layers on a polymer substrate

    NARCIS (Netherlands)

    Abdallah, Amir; Bouten, P.C.P.; Toonder, den J.M.J.; With, de G.

    2011-01-01

    Buckle initiation and delamination of patterned ITO layers on a polymer substrate were studied. Various buckle modes have been observed depending on the type of etch defects and the crack patterns. The buckle density was found to be dependent on the number of etch defects, imperfections, applied

  6. Surface modified MXene Ti3C2 multilayers by aryl diazonium salts leading to large-scale delamination

    Science.gov (United States)

    Wang, Hongbing; Zhang, Jianfeng; Wu, Yuping; Huang, Huajie; Li, Gaiye; Zhang, Xin; Wang, Zhuyin

    2016-10-01

    Herein we report a simple and facile method to delaminate MXene Ti3C2 multilayers by the assistance of surface modification using aryl diazonium salts. The basic strategy involved the preparation of layered MAX Ti3AlC2 and the exfoliation of Ti3AlC2 into Ti3C2 multilayers, followed by Na+ intercalation and surface modification using sulfanilic acid diazonium salts. The resulting chemically grafted Ti3C2 flakes were characterized by Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) to confirm the presence of the surface organic species. Ultraviolet-visible spectroscopy revealed that surface-modified MXene Ti3C2 sheets disperse well in water and the solutions obey Lambert-Beer's law. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to demonstrate the morphology and structure of delaminating MXene Ti3C2 flakes. The results indicated that chemical modification for MXene multilayers by aryl diazonium salts induced swelling that conversely weakened the bonds between MX layers, hence leading to large-scale delamination of multilayered MXene Ti3C2via mild sonication. Advantages of the present approach rely not only on the simplicity and efficiency of the delamination procedure but also on the grafting of aryl groups to MXene surfaces, highly suitable for further applications of the newly discovered two-dimensional materials.

  7. Detecting closing delaminations in laminated composite plates using nonlinear structural intensity and time reversal mirrors

    International Nuclear Information System (INIS)

    Lamberti, Alfredo; Semperlotti, Fabio

    2013-01-01

    Closing delaminations in composite laminated structures exhibit a nonlinear dynamic response when excited by high frequency elastic waves. The contact acoustic nonlinear effects taking place at the damage interface act as a mechanism of energy redistribution from the driving frequency to the nonlinear harmonic frequencies. In this paper, we extend the concept of nonlinear structural intensity (NSI) to the analysis of closing delaminations in composite laminated plates. NSI is calculated using a method based on a combination of finite element and finite difference techniques, which is suitable for processing both numerical and experimental data. NSI is proven to be an effective metric to identify the presence and location of closing delaminations. The highly directional nature of orthotropic composites results in vibrational energy propagating in a different direction from that of the initial elastic wave. This aspect reduces the ability to effectively interrogate the damage and, therefore, the sensitivity to the damage. The time reversal mirror technique is explored as a possible approach to overcome the effect of the material directionality and increase the ability to interrogate the damage. Numerical simulations show that this technique is able to overcome the material directionality and to drastically enhance the ability to interrogate the damage. (paper)

  8. Fatigue Crack and Delamination Growth in Fibre Metal Laminates under Variable Amplitude Loading

    NARCIS (Netherlands)

    Khan, S.

    2013-01-01

    This thesis presents the investigation into the fatigue propagation and delamination growth of Fibre Metal Laminates under variable amplitude loading. As explained in the first chapter, the motivation of the research is twofold: first, to obtain a clear understanding and detailed characterization of

  9. Correlating bilayer tablet delamination tendencies to micro-environmental thermodynamic conditions during pan coating.

    Science.gov (United States)

    Zacour, Brian M; Pandey, Preetanshu; Subramanian, Ganeshkumar; Gao, Julia Z; Nikfar, Faranak

    2014-06-01

    The objective of this study was to determine the impact that the micro-environment, as measured by PyroButton data loggers, experienced by tablets during the pan coating unit operation had on the layer adhesion of bilayer tablets in open storage conditions. A full factorial design of experiments (DOE) with three center points was conducted to study the impact of final tablet hardness, film coating spray rate and film coating exhaust temperature on the delamination tendencies of bilayer tablets. PyroButton data loggers were placed (fixed) at various locations in a pan coater and were also allowed to freely move with the tablet bed to measure the micro-environmental temperature and humidity conditions of the tablet bed. The variance in the measured micro-environment via PyroButton data loggers accounted for 75% of the variance in the delamination tendencies of bilayer tablets on storage (R(2 )= 0.75). A survival analysis suggested that tablet hardness and coating spray rate significantly impacted the delamination tendencies of the bilayer tablets under open storage conditions. The coating exhaust temperature did not show good correlation with the tablets' propensity to crack indicating that it was not representative of the coating micro-environment. Models created using data obtained from the PyroButton data loggers outperformed models created using primary DOE factors in the prediction of bilayer tablet strength, especially upon equipment or scale transfers. The coating micro-environment experienced by tablets during the pan coating unit operation significantly impacts the strength of the bilayer interface of tablets on storage.

  10. Cathodic delamination of seawater-immersed anticorrosive coatings: Mapping of parameters affecting the rate

    DEFF Research Database (Denmark)

    Sørensen, Per Aggerholm; Dam-Johansen, Kim; Weinell, C. E.

    2010-01-01

    Abstract: Cathodic delamination is one of the major modes of failure for organic coatings immersed in seawater and refers to the weakening or loss of adhesion between the coating and the substrate. The diminished adhesion is the result of electrochemical reactions occurring at the coating...

  11. Utilizing the meso-scale grain boundary stress to estimate the onset of delamination in 2099-T861 aluminium–lithium

    International Nuclear Information System (INIS)

    McDonald, Russell J; Beaudoin, Armand J

    2010-01-01

    Aluminium–lithium alloys provide a lower density and higher stiffness alternative to other high strength aluminium alloys. However, many Al–Li alloys exhibit a non-traditional failure mechanism called delamination, which refers to the failure of the elongated grain boundary interface. In this investigation, delaminations were observed after cyclic deformation of both uniaxial and torsion experiments. A cyclically stable rate-independent crystal plasticity framework with kinematic hardening was developed to address many experimental trends of stabilized cyclic plasticity. Utilizing this framework, meso-scale grain boundary interface stresses were estimated with uniform deformation and bi-crystal models. These models are computationally amenable to investigate both orientation dependence and the statistical nature of the grain boundary stresses for a given bulk texture and nominal loading. A coupled shear-normal Findley-based damage parameter was formulated to quantitatively characterize the nucleation of delamination consistently with experimental trends

  12. Surface modified MXene Ti{sub 3}C{sub 2} multilayers by aryl diazonium salts leading to large-scale delamination

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hongbing [College of Mechanics and Materials, Hohai University, Nanjing, Jiangsu Province 210098 (China); Department of Mathematics and Physics, Nanjing Institute of Technology, Nanjing, Jiangsu Province 211167 (China); Zhang, Jianfeng, E-mail: jfzhang_sic@163.com [College of Mechanics and Materials, Hohai University, Nanjing, Jiangsu Province 210098 (China); Wu, Yuping; Huang, Huajie; Li, Gaiye; Zhang, Xin; Wang, Zhuyin [College of Mechanics and Materials, Hohai University, Nanjing, Jiangsu Province 210098 (China)

    2016-10-30

    Highlights: • A novel and simple method to delaminate MXene Ti{sub 3}C{sub 2} multilayers. • Surface modification using aryl diazonium salts induced swelling that conversely weakened the bonds between MXene layers. • The grafting of phenylsulfonic acid groups on MXene surfaces resulted in excellent water dispersibility. - Abstract: Herein we report a simple and facile method to delaminate MXene Ti{sub 3}C{sub 2} multilayers by the assistance of surface modification using aryl diazonium salts. The basic strategy involved the preparation of layered MAX Ti{sub 3}AlC{sub 2} and the exfoliation of Ti{sub 3}AlC{sub 2} into Ti{sub 3}C{sub 2} multilayers, followed by Na{sup +} intercalation and surface modification using sulfanilic acid diazonium salts. The resulting chemically grafted Ti{sub 3}C{sub 2} flakes were characterized by Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) to confirm the presence of the surface organic species. Ultraviolet-visible spectroscopy revealed that surface-modified MXene Ti{sub 3}C{sub 2} sheets disperse well in water and the solutions obey Lambert–Beer’s law. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to demonstrate the morphology and structure of delaminating MXene Ti{sub 3}C{sub 2} flakes. The results indicated that chemical modification for MXene multilayers by aryl diazonium salts induced swelling that conversely weakened the bonds between MX layers, hence leading to large-scale delamination of multilayered MXene Ti{sub 3}C{sub 2}via mild sonication. Advantages of the present approach rely not only on the simplicity and efficiency of the delamination procedure but also on the grafting of aryl groups to MXene surfaces, highly suitable for further applications of the newly discovered two-dimensional materials.

  13. Influence of Mixed Mode I-Mode II Loading on Fatigue Delamination Growth Characteristics of a Graphite Epoxy Tape Laminate

    Science.gov (United States)

    Ratcliffe, James G.; Johnston, William M., Jr.

    2014-01-01

    Mixed mode I-mode II interlaminar tests were conducted on IM7/8552 tape laminates using the mixed-mode bending test. Three mixed mode ratios, G(sub II)/G(sub T) = 0.2, 0.5, and 0.8, were considered. Tests were performed at all three mixed-mode ratios under quasi-static and cyclic loading conditions, where the former static tests were used to determine initial loading levels for the latter fatigue tests. Fatigue tests at each mixed-mode ratio were performed at four loading levels, Gmax, equal to 0.5G(sub c), 0.4G(sub c), 0.3G(sub c), and 0.2G(sub c), where G(sub c) is the interlaminar fracture toughness of the corresponding mixed-mode ratio at which a test was performed. All fatigue tests were performed using constant-amplitude load control and delamination growth was automatically documented using compliance solutions obtained from the corresponding quasi-static tests. Static fracture toughness data yielded a mixed-mode delamination criterion that exhibited monotonic increase in Gc with mixed-mode ratio, G(sub II)/G(sub T). Fatigue delamination onset parameters varied monotonically with G(sub II)/G(sub T), which was expected based on the fracture toughness data. Analysis of non-normalized data yielded a monotonic change in Paris law exponent with mode ratio. This was not the case when normalized data were analyzed. Fatigue data normalized by the static R-curve were most affected in specimens tested at G(sub II)/G(sub T)=0.2 (this process has little influence on the other data). In this case, the normalized data yielded a higher delamination growth rate compared to the raw data for a given loading level. Overall, fiber bridging appeared to be the dominant mechanism, affecting delamination growth rates in specimens tested at different load levels and differing mixed-mode ratios.

  14. Criteria for initiation of delamination in quasi-static punch-shear tests of a carbon-fiber composite material.

    Energy Technology Data Exchange (ETDEWEB)

    Chin, Eric Brian [Sandia National Lab. (SNL-CA), Livermore, CA (United States); English, Shawn Allen [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Briggs, Timothy [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2015-09-01

    V arious phenomenological delamination initiation criteria are analyzed in quasi - static punch - shear tests conducted on six different geometries. These six geometries are modeled and analyzed using elastic, large - deformation finite element analysis. Analysis output is post - processed to assess different delamination initiation criteria, and their applicability to each of the geometries. These criteria are compared to test results to assess whether or not they are appropriate based on what occurred in testing. Further, examinations of CT scans and ultrasonic images o f test specimens are conducted in the appendix to determine the sequence of failure in each test geometry.

  15. EVALUATION OF STRENGTH TO SHEAR AND DELAMINATION IN GLUED LAMINATED WOOD

    Directory of Open Access Journals (Sweden)

    Carlito Calil Neto

    2014-12-01

    Full Text Available The Glued Laminated Wood has a large range of applications. In Brazil, its employment as cross-piece poles for overhead electrical power has attracted the attention of companies in the industry, motivated by the potential use of this material. Among the factors that influence the mechanical performance of Glulam solutions stand out efficiency and affinity of the adhesives to the species of wood used, the type of treatment and moisture content of wood veneer, motivating the development of new research on this topic. This research aimed to investigate, by Design of Experiments (DOE, the influence of wood (pinus, teca, eucalipto, adhesive (Purbond; Cascophen and treatment (CCA, CCB, CCBS in the variable responses shear strength and delamination, consisting in the same combination factors evaluated in ANEEL/EESC-PD220-07 project: Head Crosshead Glulam Series. The results of the statistical analysis showed that the species factor expressed significant effect for both response variables evaluated, did not occur with adhesive and treatment factors. Moisture content was significant in the wood evaluated when analyzed the shear strength, and the teca wood showed the highest shear strength and also relating to the delamination.

  16. Reliability and Validity of the Resistiveness to Care Scale Among Cognitively Impaired Older Adults.

    Science.gov (United States)

    Galik, Elizabeth; Resnick, Barbara; Vigne, Erin; Holmes, Sarah Dee; Nalls, Victoria

    2017-01-01

    Resistiveness to care is behavior that prevents or interferes with caregivers' performing or assisting with activities of daily living and puts residents at risk for inappropriate use of antipsychotic drugs, other restraining interventions, social isolation, and physical abuse. The purpose of this study was to establish the psychometric properties of a previously developed Resistiveness to Care measure. This was a descriptive study using baseline data from an ongoing randomized controlled trial testing a Function and Behavior Focused Care (FBFC) intervention. Residents were eligible to participate if they were 55 years of age or older, had a Mini-Mental State Exam (MMSE) score of 15 or less, and were not enrolled in hospice or admitted for subacute care. Descriptive information included age, race, gender, cognitive status, and marital status. In addition to the Resistance to Care Scale, the Barthel Index, the Physical Activity Survey in Long Term Care (PAS-LTC), and the Cohen-Mansfield Agitation Inventory (CMAI) were completed. Psychometric testing was done using Rasch analysis and the Winsteps statistical program. The participants were moderate to severely cognitively impaired (MMSE of 7.23), functionally dependent (Barthel Index 47.31, SD 27.59), and engaged in only 134.17 (SD = 207.32) minutes of physical activity daily. Reliability was supported based on a Cronbach alpha of 0.84 and the DIF analysis, as there was no difference in function of the items between male and female participants. Validity was supported as all items fit the measurement model based on INFIT and OUTFIT statistics. The findings support the reliability and validity of the Resistiveness to Care Scale for use with older adults with dementia in nursing home settings. Future work with the measure may benefit from the addition of items that are easier to endorse with regard to resistiveness to care (shutting eyes or spitting out food may be useful additions). Copyright © 2016 AMDA – The

  17. A thick level set interface model for simulating fatigue-drive delamination in composites

    NARCIS (Netherlands)

    Latifi, M.; Van der Meer, F.P.; Sluys, L.J.

    2015-01-01

    This paper presents a new damage model for simulating fatigue-driven delamination in composite laminates. This model is developed based on the Thick Level Set approach (TLS) and provides a favorable link between damage mechanics and fracture mechanics through the non-local evaluation of the energy

  18. Ductile film delamination from compliant substrates using hard overlayers.

    Science.gov (United States)

    Cordill, M J; Marx, V M; Kirchlechner, C

    2014-11-28

    Flexible electronic devices call for copper and gold metal films to adhere well to polymer substrates. Measuring the interfacial adhesion of these material systems is often challenging, requiring the formulation of different techniques and models. Presented here is a strategy to induce well defined areas of delamination to measure the adhesion of copper films on polyimide substrates. The technique utilizes a stressed overlayer and tensile straining to cause buckle formation. The described method allows one to examine the effects of thin adhesion layers used to improve the adhesion of flexible systems.

  19. Optimal Electrode Selection for Electrical Resistance Tomography in Carbon Fiber Reinforced Polymer Composites

    Science.gov (United States)

    Escalona Galvis, Luis Waldo; Diaz-Montiel, Paulina; Venkataraman, Satchi

    2017-01-01

    Electrical Resistance Tomography (ERT) offers a non-destructive evaluation (NDE) technique that takes advantage of the inherent electrical properties in carbon fiber reinforced polymer (CFRP) composites for internal damage characterization. This paper investigates a method of optimum selection of sensing configurations for delamination detection in thick cross-ply laminates using ERT. Reduction in the number of sensing locations and measurements is necessary to minimize hardware and computational effort. The present work explores the use of an effective independence (EI) measure originally proposed for sensor location optimization in experimental vibration modal analysis. The EI measure is used for selecting the minimum set of resistance measurements among all possible combinations resulting from selecting sensing electrode pairs. Singular Value Decomposition (SVD) is applied to obtain a spectral representation of the resistance measurements in the laminate for subsequent EI based reduction to take place. The electrical potential field in a CFRP laminate is calculated using finite element analysis (FEA) applied on models for two different laminate layouts considering a set of specified delamination sizes and locations with two different sensing arrangements. The effectiveness of the EI measure in eliminating redundant electrode pairs is demonstrated by performing inverse identification of damage using the full set and the reduced set of resistance measurements. This investigation shows that the EI measure is effective for optimally selecting the electrode pairs needed for resistance measurements in ERT based damage detection. PMID:28772485

  20. Influence of crystallographic texture in X70 pipeline steels on toughness anisotropy and delamination

    Science.gov (United States)

    Al-Jabr, Haytham M.

    The effects of microstructure and crystallographic texture in four commercially-produced API X70 pipeline steels and their relation to planar anisotropy of toughness and delamination were evaluated. The experimental steels were processed through either a hot strip mill, a Steckel mill, or a compact strip mill. Different processing routes were selected to obtain plates with potential variations in the microstructure and anisotropic characteristics. Tensile and Charpy impact testing were used to evaluate the mechanical properties in three orientations: longitudinal (L), transverse (T) and diagonal (D) with respect to the rolling direction to evaluate mechanical property anisotropy. The yield and tensile strengths were higher in the T orientation and toughness was lower in the D orientation for all plates. Delamination was observed in some of the ductile fracture surfaces of the impact samples. To further study the splitting behavior and effects on impact toughness, a modified impact test (MCVN) specimen with side grooves was designed to intensify induced stresses parallel to the notch root and thus facilitate evaluation of delamination. Scanning electron microscopy combined with electron backscattered diffraction (EBSD) were used to evaluate the grain size, microstructural constituents, and crystallographic texture to determine the factors leading to delamination and the anisotropy in toughness. The ferrite grain size is mainly responsible for the differences in DBTTs between the L and T orientations. The higher DBTT in the D orientation observed in pipeline steels is attributed to crystallographic texture. The higher DBTT in the D direction is due to the higher volume fraction of grains having their {100} planes parallel or close to the primary fracture plane for the D orientation. An equation based on a new "brittleness parameter," based on an assessment of grain orientations based on EBSD data, was developed to predict the changes in DBTTs with respect to sample

  1. Cohesive delamination and frictional contact on joining surface via XFEM

    Directory of Open Access Journals (Sweden)

    Francesco Parrinello

    2018-02-01

    Full Text Available In the present paper, the complex mechanical behaviour of the surfaces joining two differentbodies is analysed by a cohesive-frictional interface constitutive model. The kinematical behaviouris characterized by the presence of discontinuous displacement fields, that take place at the internalconnecting surfaces, both in the fully cohesive phase and in the delamination one. Generally, in order tocatch discontinuous displacement fields, internal connecting surfaces (adhesive layers are modelled bymeans of interface elements, which connect, node by node, the meshes of the joined bodies, requiringthe mesh to be conforming to the geometry of the single bodies and to the relevant connecting surface.In the present paper, the Extended Finite Element Method (XFEM is employed to model, both fromthe geometrical and from the kinematical point of view, the whole domain, including the connectedbodies and the joining surface. The joining surface is not discretized by specific finite elements, butit is defined as an internal discontinuity surface, whose spatial position inside the mesh is analyticallydefined. The proposed approach is developed for two-dimensional composite domains, formed by twoor more material portions joined together by means of a zero thickness adhesive layer. The numericalresults obtained with the proposed approach are compared with the results of the classical interfacefinite element approach. Some examples of delamination and frictional contact are proposed withlinear, circular and curvilinear adhesive layer.

  2. Reliability test and failure analysis of high power LED packages

    International Nuclear Information System (INIS)

    Chen Zhaohui; Zhang Qin; Wang Kai; Luo Xiaobing; Liu Sheng

    2011-01-01

    A new type application specific light emitting diode (LED) package (ASLP) with freeform polycarbonate lens for street lighting is developed, whose manufacturing processes are compatible with a typical LED packaging process. The reliability test methods and failure criterions from different vendors are reviewed and compared. It is found that test methods and failure criterions are quite different. The rapid reliability assessment standards are urgently needed for the LED industry. 85 0 C/85 RH with 700 mA is used to test our LED modules with three other vendors for 1000 h, showing no visible degradation in optical performance for our modules, with two other vendors showing significant degradation. Some failure analysis methods such as C-SAM, Nano X-ray CT and optical microscope are used for LED packages. Some failure mechanisms such as delaminations and cracks are detected in the LED packages after the accelerated reliability testing. The finite element simulation method is helpful for the failure analysis and design of the reliability of the LED packaging. One example is used to show one currently used module in industry is vulnerable and may not easily pass the harsh thermal cycle testing. (semiconductor devices)

  3. Automated detection of delamination and disbond from wavefield images obtained using a scanning laser vibrometer

    International Nuclear Information System (INIS)

    Sohn, H; Yang, J Y; Dutta, D; DeSimio, M; Olson, S; Swenson, E

    2011-01-01

    The paper presents signal and image processing algorithms to automatically detect delamination and disbond in composite plates from wavefield images obtained using a scanning laser Doppler vibrometer (LDV). Lamb waves are excited by a lead zirconate titanate transducer (PZT) mounted on the surface of a composite plate, and the out-of-plane velocity field is measured using an LDV. From the scanned time signals, wavefield images are constructed and processed to study the interaction of Lamb waves with hidden delaminations and disbonds. In particular, the frequency–wavenumber (f–k) domain filter and the Laplacian image filter are used to enhance the visibility of defects in the scanned images. Thereafter, a statistical cluster detection algorithm is used to identify the defect location and distinguish damaged specimens from undamaged ones

  4. Numerical model of glulam beam delamination in dependence on cohesive strength

    Science.gov (United States)

    Kawecki, Bartosz; Podgórski, Jerzy

    2018-01-01

    This paper presents an attempt of using a finite element method for predicting delamination of a glue laminated timber beam through a cohesive layer. There were used cohesive finite elements, quadratic stress damage initiation criterion and mixed mode energy release rate failure model. Finite element damage was equal to its complete stiffness degradation. Timber material was considered to be an orthotropic with plastic behaviour after reaching bending limit.

  5. Effect of delaminations on improvement of notch toughness at low temperatures

    International Nuclear Information System (INIS)

    Zhou, W.; Loh, N.L.

    1996-01-01

    The notched-bar impact test is often used to assess the notch toughness of engineering materials. The principle of the test is that a material absorbs a certain amount of energy when it breaks; the energy thus absorbed is an indication of the material's resistance to impact fracture. If the material is brittle, it breaks easily with a small amount of absorbed energy. If it is tough, it will absorb more energy to fracture. It has been well recognized that most engineering materials undergo a transition from notch tough to notch brittle behavior when the temperature is reduced. In the present study, however, an abnormal trend in the transition behavior was found for an austenitic stainless steel. V-notched specimens of the steel were tested under impact loading in a wide temperature range from -196 C to room temperature. Contrary to expectation, the impact energy values obtained at low temperatures were found to be much higher than those obtained at room temperature, indicating that the steel became tougher rather than more brittle when the test temperature was lowered. This intriguing phenomenon cannot be explained simply according to the tensile stress fracture criterion. Strong evidence has been obtained in the present study to show that the improvement of notch toughness at low temperatures is caused by delaminations

  6. Ag-Coated Heterostructures of ZnO-TiO2/Delaminated Montmorillonite as Solar Photocatalysts

    Directory of Open Access Journals (Sweden)

    Carolina Belver

    2017-08-01

    Full Text Available Heterostructures based on ZnO-TiO2/delaminated montmorillonite coated with Ag have been prepared by sol–gel and photoreduction procedures, varying the Ag and ZnO contents. They have been thoroughly characterized by XRD, WDXRF, UV–Vis, and XPS spectroscopies, and N2 adsorption, SEM, and TEM. In all cases, the montmorillonite was effectively delaminated with the formation of TiO2 anatase particles anchored on the clay layer’s surface, yielding porous materials with high surface areas. The structural and textural properties of the heterostructures synthesized were unaffected by the ZnO incorporated. The photoreduction led to solids with Ag nanoparticles decorating the surface. These materials were tested as photocatalysts for the degradation of several emerging contaminants with different nitrogen-bearing chemical structures under solar light. The catalysts yielded high rates of disappearance of the starting pollutants and showed quite stable performance upon successive applications.

  7. Reliability of a Simple Physical Therapist Screening Tool to Assess Errors during Resistance Exercises for Musculoskeletal Pain

    DEFF Research Database (Denmark)

    Andersen, Kenneth Jay; Sundstrup, E.; Andersen, L. L.

    2014-01-01

    The main objective was to investigate the intra- and intertester reliability of a simple screening tool assessing errors in exercise execution by visual observation. 38 participants with no previous resistance exercise experience practiced for two weeks four typical upper limb exercises using ela...

  8. Experimental Characterization and Cohesive Laws for Delamination of Off-Axis GFRP Laminates

    DEFF Research Database (Denmark)

    Lindgaard, Esben; Bak, Brian Lau Verndal

    2015-01-01

    This work experimentally characterizes mixed mode delamination in glass fibre reinforced polymer laminates taking into account the influence of the off-axis angle between the lamina orientation and the crack growth direction on the fracture properties. Thus, providing a cohesive law that enables...... analysis of 3D models in which mixed mode crack growth within laminates having anisotropic fracture properties takes place....

  9. Reliability and validity of the adapted Resistance Training Skills Battery for Children.

    Science.gov (United States)

    Furzer, Bonnie J; Bebich-Philip, Marc D; Wright, Kemi E; Reid, Siobhan L; Thornton, Ashleigh L

    2017-12-29

    Resistance training (RT) is emerging as a training modality to improve motor function and facilitate physical activity participation in children across the motor proficiency spectrum. Although RT competency assessments have been established and validated among adolescent cohorts, the extent to which these methods are suitable for assessing children's RT skills is unknown. This project aimed to assess the psychometric properties of the adapted Resistance Training Skills Battery for Children (RTSBc), in children with varying motor proficiency. Repeated measures design with 40 participants (M age=8.2±1.7years) displaying varying levels of motor proficiency. Participants performed the adapted RTSBc on two occasions, receiving a score for their execution of each component, in addition to an overall RT skill quotient child (RTSQc). Cronbach's alpha, intra-class correlation (ICC), Bland-Altman analysis, and typical error were used to assess test-retest reliability. To examine construct validity, exploratory factor analysis was performed alongside computing correlations between participants' muscle strength, motor proficiency, age, lean muscle mass, and RTSQc. The RTSBc displayed an acceptable level of internal consistency (alpha=0.86) and test-retest reliability (ICC range=0.86-0.99). Exploratory factor analysis supported internal test structure, with all six RT skills loading strongly on a single factor (range 0.56-0.89). Analyses of structural validity revealed positive correlations for RTSQc in relation to motor proficiency (r=0.52, preliability of the RTSBc, providing preliminary evidence that the RTSBc is appropriate for use in the assessment of children's RT competency. Copyright © 2018 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  10. An high order Mixed Interpolation Tensorial Components (MITC) shell element approach for modeling the buckling behavior of delaminated composites

    DEFF Research Database (Denmark)

    Gaiotti, Marco; Rizzo, Cesare M.; Branner, Kim

    2014-01-01

    This paper describes the experimental and numerical studies carried out on delaminated fiberglass epoxy resin laminates made-up by different fabrication methods, namely by vacuum infusion and prepreg. While the tested specimens were originally intended for the assessment of buckling behavior...... of composite laminates of wind turbine blades, results were found valuable for the marine industry as well, because similar laminates are used for the hull shell and stiffeners. Systematic calculations were carried out to assess the effects of an embedded delamination on the buckling load, varying the size...

  11. Corrosion-Resistant Roof with Integrated Photovoltaic Power System

    Science.gov (United States)

    2014-02-01

    Figure 9. The panels are coated with a PVDF organic coating on the external facing surface and polyester enamel on the interior-facing surface. The high...1 no scribe No evidence of blistering, cracking , peeling or delaminating #2 scribe No evidence of blistering, cracking , peeling or delaminating...3 scribe No evidence of blistering, cracking , peeling or delaminating #4 scribe No evidence of blistering, cracking , peeling or delaminating

  12. Numerical simulations and experimental measurements of steel and ice impacts on concrete for acoustic interrogation of delaminations in bridge decks

    Energy Technology Data Exchange (ETDEWEB)

    Mazzeo, Brian A.; Patil, Anjali N.; Klis, Jeffrey M. [Brigham Young University, Department of Electrical and Computer Engineering, Provo, Utah, 84602 (United States); Hurd, Randy C.; Truscott, Tadd T. [Brigham Young University, Department of Mechanical Engineering, Provo, Utah, 84602 (United States); Guthrie, W. Spencer [Brigham Young University, Department of Civil and Environmental Engineering, Provo, Utah, 84602 (United States)

    2014-02-18

    Delaminations in bridge decks typically result from corrosion of the top mat of reinforcing steel, which leads to a localized separation of the concrete cover from the underlying concrete. Because delaminations cannot be detected using visual inspection, rapid, large-area interrogation methods are desired to characterize bridge decks without disruption to traffic, without the subjectivity inherent in existing methods, and with increased inspector safety. To this end, disposable impactors such as water droplets or ice chips can be dropped using automatic dispensers onto concrete surfaces to excite mechanical vibrations while acoustic responses can be recorded using air-coupled microphones. In this work, numerical simulations are used to characterize the flexural response of a model concrete bridge deck subject to both steel and ice impactors, and the results are compared with similar experiments performed in the laboratory on a partially delaminated concrete bridge deck slab. The simulations offer greater understanding of the kinetics of impacts and the responses of materials.

  13. Ballistic protection performance of curved armor systems with or without debondings/delaminations

    International Nuclear Information System (INIS)

    Tan, Ping

    2014-01-01

    Highlights: • Influence of pre-existing defect in an armor system on its ballistic performance. • Development of finite element models for the ballistic performance of armor systems. • Prediction of the ballistic limit and back face deformation of curved armor systems. - Abstract: In order to discern how pre-existing defects such as single or multiple debondings/delaminations in a curved armor system may affect its ballistic protection performance, two-dimensional axial finite element models were generated using the commercial software ANSYS/Autodyn. The armor systems considered in this investigation are composed of boron carbide front component and Kevlar/epoxy backing component. They are assumed to be perfectly bonded at the interface without defects. The parametric study shows that for the cases considered, the maximum back face deformation of a curved armor system with or without defects is more sensitive to its curvature, material properties of the ceramic front component, and pre-existing defect size and location than the ballistic limit velocity. Additionally, both the ballistic limit velocity and maximum back face deformation are significantly affected by the backing component thickness, front/backing component thickness ratio and the number of delaminations

  14. Measurement of adherence of residually stressed thin films by indentation. I. Mechanics of interface delamination

    International Nuclear Information System (INIS)

    Marshall, D.B.; Evans, A.G.

    1984-01-01

    A fracture analysis of indentation-induced delamination of thin films is presented. The analysis is based on a model system in which the section of film above the delaminating crack is treated as a rigidly clamped disc, and the crack extension force is derived from changes in strain energy of the system as the crack extends. Residual deposition stresses influence the cracking response by inducing buckling of the film above the crack and by providing an additional crack driving force once buckling occurs. A relation for the equilibrium crack length is derived in terms of the indenter load and geometry, the film thickness and mechanical properties, the residual stress level and the fracture toughness of the interface. The analysis provides a basis for using controlled indentation cracking as a quantitative measure of interface toughness and for evaluating contact-induced damage in thin films

  15. Stress Intensity of Delamination in a Sintered-Silver Interconnection: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    DeVoto, D. J.; Paret, P. P.; Wereszczak, A. A.

    2014-08-01

    In automotive power electronics packages, conventional thermal interface materials such as greases, gels, and phase-change materials pose bottlenecks to heat removal and are also associated with reliability concerns. The industry trend is toward high thermal performance bonded interfaces for large-area attachments. However, because of coefficient of thermal expansion mismatches between materials/layers and resultant thermomechanical stresses, adhesive and cohesive fractures could occur, posing a reliability problem. These defects manifest themselves in increased thermal resistance. This research aims to investigate and improve the thermal performance and reliability of sintered-silver for power electronics packaging applications. This has been experimentally accomplished by the synthesis of large-area bonded interfaces between metalized substrates and copper base plates that have subsequently been subjected to thermal cycles. A finite element model of crack initiation and propagation in these bonded interfaces will allow for the interpretation of degradation rates by a crack-velocity (V)-stress intensity factor (K) analysis. A description of the experiment and the modeling approach are discussed.

  16. Simulation of delamination crack growth in composite laminates: application of local and non-local interface damage models

    International Nuclear Information System (INIS)

    Ijaz, H.; Asad, M.

    2015-01-01

    The use of composite laminates is increasing in these days due to higher strength and low density values in comparison of metals. Delamination is a major source of failure in composite laminates. Damage mechanics based theories are employed to simulate the delamination phenomena between composite laminates. These damage models are inherently local and can cause the concentration of stresses around the crack tip. In the present study integral type non-local damage formulation is proposed to avoid the localization problem associated to damage formulation. A comprehensive study is carried out for the models and classical local damage model are performed and results are compared with available experimental data for un IMS/924 Carbon/fiber epoxy composite laminate. (author)

  17. Evaluation of seismic reliability of steel moment resisting frames rehabilitated by concentric braces with probabilistic models

    Directory of Open Access Journals (Sweden)

    Fateme Rezaei

    2017-08-01

    Full Text Available Probability of structure failure which has been designed by "deterministic methods" can be more than the one which has been designed in similar situation using probabilistic methods and models considering "uncertainties". The main purpose of this research was to evaluate the seismic reliability of steel moment resisting frames rehabilitated with concentric braces by probabilistic models. To do so, three-story and nine-story steel moment resisting frames were designed based on resistant criteria of Iranian code and then they were rehabilitated based on controlling drift limitations by concentric braces. Probability of frames failure was evaluated by probabilistic models of magnitude, location of earthquake, ground shaking intensity in the area of the structure, probabilistic model of building response (based on maximum lateral roof displacement and probabilistic methods. These frames were analyzed under subcrustal source by sampling probabilistic method "Risk Tools" (RT. Comparing the exceedance probability of building response curves (or selected points on it of the three-story and nine-story model frames (before and after rehabilitation, seismic response of rehabilitated frames, was reduced and their reliability was improved. Also the main effective variables in reducing the probability of frames failure were determined using sensitivity analysis by FORM probabilistic method. The most effective variables reducing the probability of frames failure are  in the magnitude model, ground shaking intensity model error and magnitude model error

  18. Continental Delamination of the Romanian Eastern Carpathians: A Lower Crustal Origin of the Vrancea Seismogenic Zone?

    Science.gov (United States)

    Fillerup, M. A.; Knapp, J. H.; Knapp, C. C.

    2006-12-01

    Two lithosphere-scale, explosive-source seismic reflection profiles (DRACULA I and DACIA PLAN), inclusive of the hinterland and foreland of the Romanian Eastern Carpathians, provide new evidence for the geodynamic origin of the Vrancea Seismogenic Zone (VSZ) of Romania. These data, collected to evaluate existing subduction-related and delamination geodynamic models proposed to explain the intermediate depth seismicity associated with the Vrancea zone, show evidence of continental crust extending continuously above the VSZ from the Carpathian foreland well into the Transylvanian hinterland. Crustal thicknesses inferred from these data based on reflectivity show a 40-45 km crust below the Transylvanian basin abruptly shallowing to 32 km for ~120 km beneath the fold and thrust belt of the main Carpathian orogen and thickening again to 38-42 km crust in the foreland. This thinned crust outlines an apparent lower crustal sub-orogenic cavity that is overlain by a relatively subhorizontal reflective fabric absent of dipping reflectivity. The northwest dipping Vrancea seismogenic body, a 30x70x200 km volume of intermediate depth earthquakes, is located on the eastern flank of the apparently thin crust beneath the Carpathian orogen. Amplitude decay curves show penetration of seismic energy to a depth of ~60 km in the vicinity of the sub-orogenic cavity, implying this non- reflective zone is a geologic signature. Rotation of the VSZ about a hinge beneath the foreland basin at a depth of ~50 km restores to fill the lower-crustal cavity under the orogen, suggesting the VSZ represents a portion of brittle lower crust delaminated during continental lithospheric delamination which may have caused regional uplift of the Transylvanian basin. The lack of through-going, dipping crustal-scale boundaries along this composite lithospheric transect would appear to preclude subduction as an explanation for seismicity in the VSZ, consistent with abundant surface geologic data. These

  19. Structural systems reliability analysis

    International Nuclear Information System (INIS)

    Frangopol, D.

    1975-01-01

    For an exact evaluation of the reliability of a structure it appears necessary to determine the distribution densities of the loads and resistances and to calculate the correlation coefficients between loads and between resistances. These statistical characteristics can be obtained only on the basis of a long activity period. In case that such studies are missing the statistical properties formulated here give upper and lower bounds of the reliability. (orig./HP) [de

  20. COMPOSITIONAL AND THERMAL DIFFERENCES BETWEEN LITHOSPHERIC AND ASTHENOSPHERIC MANTLE AND THEIR INFLUENCE ON CONTINENTAL DELAMINATION

    Directory of Open Access Journals (Sweden)

    A. I. Kiselev

    2015-01-01

    Full Text Available The lower part of lithosphere in collisional orogens may delaminate due to density inversion between the asthenosphere and the cold thickened lithospheric mantle. Generally, standard delamination models have neglected density changes within the crust and the lithospheric mantle, which occur due to phase transitions and compositional variations upon changes of P-T parameters. Our attention is focused on effects of phase and density changes that may be very important and even dominant when compared with the effect of a simple change of the thermal mantle structure. The paper presents the results of numerical modeling for eclogitization of basalts of the lower crust as well as phase composition changes and density of underlying peridotite resulted from tectonic thickening of the lithosphere and its foundering into the asthenosphere. As the thickness of the lower crust increases, the mafic granulite (basalt passes into eclogite, and density inversion occurs at the accepted crust-mantle boundary (P=20 kbar because the newly formed eclogite is heavier than the underlying peridotite by 6 % (abyssal peridotite, according to [Boyd, 1989]. The density difference is a potential energy for delamination of the eclogitic portion of the crust. According to the model, P=70 kbar and T=1300 °C correspond to conditions at the lower boundary of the lithosphere. Assuming the temperature adiabatic distribution within the asthenosphere, its value at the given parameters ranges from 1350 °C to 1400 °C. Density inversion at dry conditions occurs with the identical lithospheric and asthenospheric compositions at the expense of the temperature difference at 100 °C with the density difference of only 0.0022 %. Differences of two other asthenospheric compositions (primitive mantle, and lherzolite KH as compared to the lithosphere (abyssal peridotite are not compensated for by a higher temperature. The asthenospheric density is higher than that of the lithospheric base

  1. Delaminated Transfer of CVD Graphene

    Science.gov (United States)

    Clavijo, Alexis; Mao, Jinhai; Tilak, Nikhil; Altvater, Michael; Andrei, Eva

    Single layer graphene is commonly synthesized by dissociation of a carbonaceous gas at high temperatures in the presence of a metallic catalyst in a process known as Chemical Vapor Deposition or CVD. Although it is possible to achieve high quality graphene by CVD, the standard transfer technique of etching away the metallic catalyst is wasteful and jeopardizes the quality of the graphene film by contamination from etchants. Thus, development of a clean transfer technique and preservation of the parent substrate remain prominent hurdles to overcome. In this study, we employ a copper pretreatment technique and optimized parameters for growth of high quality single layer graphene at atmospheric pressure. We address the transfer challenge by utilizing the adhesive properties between a polymer film and graphene to achieve etchant-free transfer of graphene films from a copper substrate. Based on this concept we developed a technique for dry delamination and transferring of graphene to hexagonal boron nitride substrates, which produced high quality graphene films while at the same time preserving the integrity of the copper catalyst for reuse. DOE-FG02-99ER45742, Ronald E. McNair Postbaccalaureate Achievement Program.

  2. Moisture-Induced Delamination Video of an Oxidized Thermal Barrier Coating

    Science.gov (United States)

    Smialek, James L.; Zhu, Dongming; Cuy, Michael D.

    2008-01-01

    PVD TBC coatings were thermally cycled to near-failure at 1150 C. Normal failure occurred after 200 to 300 1-hr cycles with only moderate weight gains (0.5 mg/sq cm). Delamination and buckling was often delayed until well after cooldown (desktop spallation), but could be instantly induced by the application of water drops, as shown in a video clip which can be viewed by clicking on figure 2 of this report. Moisture therefore plays a primary role in delayed desktop TBC failure. Hydrogen embrittlement is proposed as the underlying mechanism.

  3. Material and design considerations of FBGA reliability performance

    International Nuclear Information System (INIS)

    Lee, Teck Kheng; Ng, T.C.; Chai, Y.M.

    2004-01-01

    FBGA package reliability is usually assessed through the conventional approaches of die attach and mold compound material optimization. However, with the rapid changes and fast-moving pace of electronic packaging and the introduction of new soldermask and core materials, substrate design has also become a critical factor in determining overall package reliability. The purpose of this paper is to understand the impact design and soldermask material of a rigid substrate on overall package reliability. Three different soldermask patterns with a matrix of different die attach, mold compound, and soldermask materials are assessed using the moisture sensitivity test (MST). Package reliability is also assessed through the use of temperature cycling (T/C) at conditions 'B' and 'C'. For material optimization, three different mold compounds and die attach materials are used. Material adhesion between different die attach materials and soldermask materials are obtained through die shear performed at various temperatures and preset moisture conditions. A study correlating the different packaging material properties and their relative adhesion strengths with overall package reliability in terms of both MST and T/C performance was performed. Soldermask design under the die pads was found to affect package reliability. For example, locating vias at the edge of the die is not desirable because the vias acts as initiation point for delamination and moisture-induced failure. Through die shear testing, soldermask B demonstrated higher adhesion properties compared to soldermask A across several packaging materials and enhanced the overall package reliability in terms of both MST and T/C performance. Both MST JEDEC level 1 and the T/C of 'B' and 'C' at 1000 cycles have been achieved through design and package material optimization

  4. Modeling delamination of FRP laminates under low velocity impact

    Science.gov (United States)

    Jiang, Z.; Wen, H. M.; Ren, S. L.

    2017-09-01

    Fiber reinforced plastic laminates (FRP) have been increasingly used in various engineering such as aeronautics, astronautics, transportation, naval architecture and their impact response and failure are a major concern in academic community. A new numerical model is suggested for fiber reinforced plastic composites. The model considers that FRP laminates has been constituted by unidirectional laminated plates with adhesive layers. A modified adhesive layer damage model that considering strain rate effects is incorporated into the ABAQUS / EXPLICIT finite element program by the user-defined material subroutine VUMAT. It transpires that the present model predicted delamination is in good agreement with the experimental results for low velocity impact.

  5. Validity and reliability of a controlled pneumatic resistance exercise device.

    Science.gov (United States)

    Paulus, David C; Reynolds, Michael C; Schilling, Brian K

    2008-01-01

    During the concentric portion of the free-weight squat exercise, accelerating the mass from rest results in a fluctuation in ground reaction force. It is characterized by an initial period of force greater than the load while accelerating from rest followed by a period of force lower than the external load during negative acceleration. During the deceleration phase, less force is exerted and muscles are loaded sub-optimally. Thus, using a reduced inertia form of resistance such as pneumatics has the capability to minimize these inertial effects as well as control the force in real time to maximize the force exerted over the exercise cycle. To improve the system response of a preliminary design, a squat device was designed with a reduced mass barbell and two smaller pneumatic cylinders. The resistance was controlled by regulating cylinder pressure such that it is capable of adjusting force within a repetition to maximize force exerted during the lift. The resistance force production of the machine was statically validated with the input voltage and output force R2 =0.9997 for at four increments of the range of motion, and the intraclass correlation coefficient (ICC) between trials at the different heights equaled 0.999. The slew rate at three forces was 749.3 N/s +/- 252.3. Dynamic human subject testing showed the desired input force correlated with average and peak ground reaction force with R2 = 0.9981 and R2 = 0.9315, respectively. The ICC between desired force and average and peak ground reaction force was 0.963. Thus, the system is able to deliver constant levels of static and dynamic force with validity and reliability. Future work will be required to develop the control strategy required for real-time control, and performance testing is required to determine its efficacy.

  6. A comparative study on free vibration analysis of delaminated torsion stiff and bending stiff composite shells

    International Nuclear Information System (INIS)

    Dey, Sudip; Karmakar, Amit

    2013-01-01

    This paper presents a finite element method to compare the effects of delamination on free vibration of graphite-epoxy bending stiff and torsion stiff composite pretwisted shallow conical shells. The generalized dynamic equilibrium equation is derived from Lagrange's equation of motion neglecting the Coriolis effect for moderate rotational speeds. An eight noded isoparametric plate bending element is employed incorporating rotary inertia and effects of transverse shear deformation based on Mindlin's theory. The multipoint constraint; algorithm is utilized to ensure the compatibility of deformation and equilibrium of resultant forces and moments at the delamination crack front. The standard eigen value problem is solved by applying the QR iteration algorithm. Mode shapes for typical configurations are also depicted. Numerical results obtained are the first known non-dimensional frequencies which could serve as reference solutions for the future investigators.

  7. Enhancement of Impact Toughness by Delamination Fracture in a Low-Alloy High-Strength Steel with Al Alloying

    Science.gov (United States)

    Sun, Junjie; Jiang, Tao; Liu, Hongji; Guo, Shengwu; Liu, Yongning

    2016-12-01

    The effect of delamination toughening of martensitic steel was investigated both at room and low temperatures [253 K and 233 K (-20 °C and -40 °C)]. Two low-alloy martensitic steels with and without Al alloying were both prepared. Layered structure with white band and black matrix was observed in Al alloyed steel, while a homogeneous microstructure was displayed in the steel without Al. Both steels achieved high strength (tensile strength over 1600 MPa) and good ductility (elongation over 11 pct), but they displayed stark contrasts on impact fracture mode and Charpy impact energy. Delamination fracture occurred in Al alloyed steel and the impact energies were significantly increased both at room temperature (from 75 to 138 J, i.e., nearly improved up to 2 times) and low temperatures [from 47.9 to 71.3 J at 233 K (-40 °C)] compared with the one without Al. Alloying with Al promotes the segregation of Cr, Mn, Si and C elements to form a network structure, which is martensite with higher carbon content and higher hardness than that of the matrix. And this network structure evolved into a band structure during the hot rolling process. The difference of yield stress between the band structure and the matrix gives rise to a delamination fracture during the impact test, which increases the toughness greatly.

  8. Assessment of Composite Delamination Self-Healing Via Micro-Encapsulation

    Science.gov (United States)

    O'Brien, T. Kevin; White, Scott R.

    2008-01-01

    Composite skin/stringer flange debond specimens manufactured from composite prepreg containing interleaf layers with a polymer based healing agent encapsulated in thin walled spheres were tested. As a crack develops and grows in the base polymer, the spheres fracture releasing the healing agent. The agent reacts with catalyst and polymerizes healing the crack. In addition, through-thickness reinforcement, in the form of pultruded carbon z-pins were included near the flange tips to improve the resistance to debonding. Specimens were manufactured with 14 plies in the skin and 10 plies in the stiffener flange. Three-point bend tests were performed to measure the skin/stiffener debonding strength and the recovered strength after healing. The first three tests performed indicated no healing following unloading and reloading. Micrographs showed that delaminations could migrate to the top of the interleaf layer due to the asymmetric loading, and hence, bypass most of the embedded capsules. For two subsequent tests, specimens were clamped in reverse bending before reloading. In one case, healing was observed as evidenced by healing agent that leaked to the specimen edge forming a visible "scar". The residual strength measured upon reloading was 96% of the original strength indicating healing had occurred. Hence, self-healing is possible in fiber reinforced composite material under controlled conditions, i.e., given enough time and contact with pressure on the crack surfaces. The micro-encapsulation technique may prove more robust when capsule sizes can be produced that are small enough to be embedded in the matrix resin without the need for using an interleaf layer. However, in either configuration, the amount of healing that can occur may be limited to the volume of healing agent available relative to the crack volume that must be filled.

  9. Material and design considerations of FBGA reliability performance

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Teck Kheng; Ng, T.C.; Chai, Y.M

    2004-09-01

    FBGA package reliability is usually assessed through the conventional approaches of die attach and mold compound material optimization. However, with the rapid changes and fast-moving pace of electronic packaging and the introduction of new soldermask and core materials, substrate design has also become a critical factor in determining overall package reliability. The purpose of this paper is to understand the impact design and soldermask material of a rigid substrate on overall package reliability. Three different soldermask patterns with a matrix of different die attach, mold compound, and soldermask materials are assessed using the moisture sensitivity test (MST). Package reliability is also assessed through the use of temperature cycling (T/C) at conditions 'B' and 'C'. For material optimization, three different mold compounds and die attach materials are used. Material adhesion between different die attach materials and soldermask materials are obtained through die shear performed at various temperatures and preset moisture conditions. A study correlating the different packaging material properties and their relative adhesion strengths with overall package reliability in terms of both MST and T/C performance was performed. Soldermask design under the die pads was found to affect package reliability. For example, locating vias at the edge of the die is not desirable because the vias acts as initiation point for delamination and moisture-induced failure. Through die shear testing, soldermask B demonstrated higher adhesion properties compared to soldermask A across several packaging materials and enhanced the overall package reliability in terms of both MST and T/C performance. Both MST JEDEC level 1 and the T/C of 'B' and 'C' at 1000 cycles have been achieved through design and package material optimization.

  10. Delamination wear mechanism in gray cast irons

    International Nuclear Information System (INIS)

    Salehi, M.

    2000-01-01

    An investigation of the friction and sliding wear of gray cast iron against chromium plated cast irons was carried out on a newly constructed reciprocating friction and wear tester. The tests were the first to be done on the test rig under dry conditions and at the speed of 170 cm/min, and variable loads of 20-260 N for a duration of 15 min. to 3 hours. The gray cast iron surfaces worn by a process of plastic deformation at the subsurface, crack nucleation, and crack growth leading to formation of plate like debris and therefore the delamination theory applies. No evidence of adhesion was observed. This could be due to formation of oxides on the wear surface which prevent adhesion. channel type chromium plating ''picked'' up cast iron from the counter-body surfaces by mechanically trapping cast iron debris on and within the cracks. The removal of the plated chromium left a pitted surface on the cast iron

  11. Analysis and modeling of delamination factor in drilling of woven kenaf fiber reinforced epoxy using Box Behnken experimental design

    Science.gov (United States)

    Suhaily, M.; Che Hassan, C. H.; Jaharah, A. G.; Afifah, M. A.; Nor Khairusshima, M. K.

    2018-01-01

    In this research study, it presents a comprehensive mathematical model for correlating the influences of drilling parameters on the delamination factor during the drilling of woven kenaf fiber reinforced epoxy composite laminates using the Box Behnken experimental design. The purpose of this study is to investigate the influence of drilling parameters such as cutting speed, feed rate and drill sizes on the delamination produced when drilling woven kenaf reinforced epoxy composite using the non-coated HSS drill bits. The damage generated on the woven kenaf reinforced epoxy composite laminates were observed both at the entrance and exit surface during the drilling operation. The experiments were conducted according to the Box Behnken experimental designs.

  12. Restraining Na-Montmorillonite Delamination in Water by Adsorption of Sodium Dodecyl Sulfate or Octadecyl Trimethyl Ammonium Chloride on the Edges

    Directory of Open Access Journals (Sweden)

    Hongliang Li

    2016-08-01

    Full Text Available The delamination of montmorillonite in water leads to sliming in ore slurry, which is detrimental to mineral flotation and solid/water separation. In this work, the delamination of Na-montmorillonite (Na-MMT has been restrained by sodium dodecyl sulfate (SDS or octadecyl trimethyl ammonium chloride (1831 through the adsorption on the edge of the mineral. The experimental results have shown that the pretreatment by adding SDS and 1831 could greatly reduce the Stokes size percentage of −1.1 µm particles in the aqueous Na-MMT suspension. From the X-ray diffractometer (XRD results, the interlayer spacing of the MMT pre-treated by SDS and 1831 is smaller than that of original MMT particles. Adsorption position of SDS and 1831 on MMT surfaces was analyzed by the measurements of adsorption capacity of SDS and 1831, inductively-coupled plasma spectra, and zeta potential before and after the plane surface of MMT was covered with tetraethylenepentaminecopper ([Cu(tetren]2+. The results indicated that SDS and 1831 are adsorbed on the edge and the whole surface of Na-MMT, respectively. Delamination of MMT could be well restrained by the adsorption of SDS and 1831 on the edges of MMT.

  13. The influence of a delaminated layer on the impedance spectrum of an operating solid oxide fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Gazzarri, J.I. [British Columbia Univ., Vancouver, BC (Canada). Dept. of Mechanical Engineering; Kesler, O. [National Research Council of Canada, Vancouver, BC (Canada). Inst. for Fuel Cell Innovation

    2005-07-01

    The development of a 2-dimensional finite element model of Solid Oxide Fuel Oxide (SOFC) AC impedance behavior was discussed. The model was developed to simulate the frequency response of a single cell with and without mechanical damage. Impedance spectroscopy was used in the development of a diagnostic technique to identify a delamination failure within a working SOFC. Changes in the impedance spectrum of a working cell were observed on the appearance of a delamination between 2 adjacent layers. The intent was to identify distinctive patterns in the cracked cell spectra that provide enough information about the degradation process so that it can be recognized and distinguished from other electrochemical processes and degradation modes. It was anticipated that the method will provide a useful tool for both maintenance and research purposes, providing insight into the causes of inadequate functioning. Results indicate that the presence of mechanically induced damage within the components of an SOFC can be detected by comparing the frequency response of the undamaged cell with that of a cell in which in-plane cracking or delamination has occurred. The presence of such defects manifests itself as a new semicircle in the Nyquist impedance diagram of the full cell, with a relaxation frequency of approximately 35 kHz. It was concluded that the ability to distinguish the crack-induced semicircle from the semicircles induced by electrochemical reactions depended on the difference between the characteristic relaxation times and their relative sizes. 17 refs., 1 tab.,10 figs.

  14. Confinement - assisted shock-wave-induced thin-film delamination (SWIFD) of copper indium gallium diselenide (CIGS) on a flexible substrate

    Science.gov (United States)

    Lorenz, Pierre; Zagoranskiy, Igor; Ehrhardt, Martin; Han, Bing; Bayer, Lukas; Zimmer, Klaus

    2017-12-01

    The laser structuring of CIGS (copper indium gallium (di)selenide) solar cell material without influence and damaging the functionality of the active layer is a challenge for laser methods The shock-wave-induced thin-film delamination (SWIFD) process allows structuring without thermal modifications due to a spatial separation of the laser absorption from the functional layer removal process. In the present study, SWIFD structuring of CIGS solar cell stacks was investigated. The rear side of the polyimide was irradiated with a KrF-Excimer laser. The laser-induced ablation process generates a traverse shock wave, and the interaction of the shock wave with the layer-substrate interface results in a delamination process. The effect of a water confinement on the SWIFD process was studied where the rear side of the substrate was covered with a ∼2 mm thick water layer. The resultant surface morphology was analysed and discussed. At a sufficient number of laser pulses N and laser fluences Φ, the CIGS layer can be selectively removed from the Mo back contact. The water confinement, as well as the increasing laser beam size A0 and N, results in the reduction of the necessary minimal laser fluence Φth. Further, the delaminated CIGS area increased with increasing Φ, N, and A0.

  15. Effects of tensile and compressive in-plane stress fields on adhesion in laser induced delamination experiments

    NARCIS (Netherlands)

    Fedorov, A.; Vellinga, W. P.; De Hosson, J. Th. M.

    2008-01-01

    In this work, the adhesion of a polymer coating on steel substrate subjected to uniaxial tensile plastic deformations was studied with the laser induced delamination technique. A decrease in the practical work of adhesion has been measured as the deformation of the substrate progressed. Moreover, it

  16. In situ characterization of delamination and crack growth of a CGO–LSM multi-layer ceramic sample investigated by X-ray tomographic microscopy

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Esposito, Vincenzo; Lauridsen, Erik Mejdal

    2014-01-01

    The densification, delamination and crack growth behavior in a Ce0.9Gd0.1O1.95 (CGO) and (La0.85Sr0.15)0.9MnO3 (LSM) multi-layer ceramic sample was studied using in situ X-ray tomographic microscopy (microtomography) to investigate the critical dynamics of crack propagation and delamination...... in a multilayered sample. Naturally occurring defects, caused by the sample preparation process, are shown not to be critical in sample degradation. Instead defects are nucleated during the debinding step. Crack growth is significantly faster along the material layers than perpendicular to them, and crack growth...

  17. Investigation on amorphous InGaZnO based resistive switching memory with low-power, high-speed, high reliability

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Yang-Shun [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan, ROC (China); Liu, Po-Tsun, E-mail: ptliu@mail.nctu.edu.tw [Department of Photonics and Display Institute, National Chiao Tung University, Hsinchu 30010, Taiwan, ROC (China); Hsu, Ching-Hui [Department of Photonics and Display Institute, National Chiao Tung University, Hsinchu 30010, Taiwan, ROC (China)

    2013-12-31

    Recently, non-volatile memory (NVM) has been widely used in electronic devices. Nowadays, the prevailing NVM is Flash memory. However, it is generally believed that the conventional Flash memory will approach its scaling limit within about a decade. The resistive random access memory (RRAM) is emerging as one of the potential candidates for future memory replacement because of its high storage density, low power consumption as well as simple structure. The purpose of this work is to develop a reliable a-InGaZnO based resistive switching memory. We investigate the resistive switching characteristics of TiN/Ti/IGZO/Pt structure and TiN/IGZO/Pt structure. The device with TiN/Ti/IGZO/Pt structure exhibits stable bipolar resistive switching. The impact of inserting a Ti interlayer is studied by material analyses. The device shows excellent resistive switching properties. For example, the DC sweep endurance can achieve over 1000 times; and the pulse induced switching cycles can reach at least 10,000 times. Furthermore, the impact of different sputtering ambience, the variable temperature measurement, and the conduction mechanisms are also investigated. According to our experiments, we propose a model to explain the resistive switching phenomenon observed in our devices.

  18. Fundamentals of EUV resist-inorganic hardmask interactions

    Science.gov (United States)

    Goldfarb, Dario L.; Glodde, Martin; De Silva, Anuja; Sheshadri, Indira; Felix, Nelson M.; Lionti, Krystelle; Magbitang, Teddie

    2017-03-01

    High resolution Extreme Ultraviolet (EUV) patterning is currently limited by EUV resist thickness and pattern collapse, thus impacting the faithful image transfer into the underlying stack. Such limitation requires the investigation of improved hardmasks (HMs) as etch transfer layers for EUV patterning. Ultrathin (<5nm) inorganic HMs can provide higher etch selectivity, lower post-etch LWR, decreased defectivity and wet strippability compared to spin-on hybrid HMs (e.g., SiARC), however such novel layers can induce resist adhesion failure and resist residue. Therefore, a fundamental understanding of EUV resist-inorganic HM interactions is needed in order to optimize the EUV resist interfacial behavior. In this paper, novel materials and processing techniques are introduced to characterize and improve the EUV resist-inorganic HM interface. HM surface interactions with specific EUV resist components are evaluated for open-source experimental resist formulations dissected into its individual additives using EUV contrast curves as an effective characterization method to determine post-development residue formation. Separately, an alternative adhesion promoter platform specifically tailored for a selected ultrathin inorganic HM based on amorphous silicon (aSi) is presented and the mitigation of resist delamination is exemplified for the cases of positive-tone and negative-tone development (PTD, NTD). Additionally, original wafer priming hardware for the deposition of such novel adhesion promoters is unveiled. The lessons learned in this work can be directly applied to the engineering of EUV resist materials and processes specifically designed to work on such novel HMs.

  19. Automatic delamination defect detection in radiographic sequence of rocket boosters

    International Nuclear Information System (INIS)

    Rebuffel, V.; Pires, S.; Caplier, A.; Lamarque, P.

    2003-01-01

    Solid rocket motors are routinely examined in real-time X-ray radioscopic mode. The large and cylindrical boosters are rotating between a high energy source and a two dimensional detector. The purpose of this control is to detect possible defects all through the sample. In the tangential configuration, the part of the object that intersects the X-rays beam is the peripheral one, allowing to detect the delamination defect between the propellant and the external metal envelope. But the defect detectability is very poor due to the strong attenuation of the X-rays through the motors. During the rotation of the booster, the system acquires a sequence of radiographs where the defects are visible over several successive instants. We have previously developed a real-time tomo-synthesis system, processing the radiographs on line, and based on a tomo-synthesis reconstruction algorithm in order to improve the signal-to-noise ratio. This system is installed at the industrial site of Kourou, and is currently used by the operators in charge of the visual inspection of the boosters. In this paper, we present a method that processes the digital images obtained by the system in the purpose of automatically extracting the delamination defects. Due to the size and the poor contrast of the defects, a single image is not sufficient to perform this detection. A spatio-temporal aspect is required for the algorithm to be robust and efficient. In a first step, the proposed method computes the apparent local displacement between the current radiograph and a reference one. This reference image is acquired at the beginning of the rotation, with few noise, and is supposed to be defect free. The apparent displacement is due to the non-perfect rotation positioning. It may be uniform or not, depending on the deformation of the insulation liner of the metallic wall. The images are then registered and compared. On the resulting difference image we apply a smoothed threshold to obtain an

  20. Characterization of the adhesion of thin film by Cross-Sectional Nanoindentation. Analysis of the substrate edge chipping and the film delamination

    Science.gov (United States)

    Felder, Eric; Roy, Sébastien; Darque-Ceretti, Evelyne

    2011-07-01

    Cross-Sectional Nanoindentation (CSN) is a recent method for adhesion measurement of nanoscale thin films in Ultra-Large Scale Integrated circuits. In the case of ductile thin films, the motion of the substrate chip implies significant plastic deformation of the film and complex geometry of delaminated areas. This article recalls first the experimental procedure and the two main features observed in this test performed on various plane copper films deposited on silicon: the critical force producing silicon edge chipping increases linearly with the distance of the indenter to the interface; on the section the delaminated length of the film ( a-b) is proportional to the residual silicon chip displacement u and the ratio S=u/(a-b) depends on the manufacturing process of the film, and is so related to its adhesion to the substrate. One proposes a simple analysis of the silicon edge chipping. Then a model of pull-off of an elastic-strain hardening plastic film is developed, which suggests an explanation for the delamination process. Application of the model to experimental results starting from films plastic properties deduced from nanoindentation measurements provides plausible results. Some improvements for performing the CSN test are proposed in order to make easier its interpretation.

  1. Comparison of histologic healing and biomechanical characteristics between repair techniques for a delaminated rotator cuff tear in rabbits.

    Science.gov (United States)

    Cheon, Sang-Jin; Kim, Jung-Han; Gwak, Heui-Chul; Kim, Chang-Wan; Kim, Jeon-Kyo; Park, Ji-Hwan

    2017-05-01

    The purpose of this study was to compare histologic healing and biomechanical characteristics between 2 repair techniques (layer by layer, repair of each layer to bone separately; and whole layer, repair of each layer to the bone en masse) for delaminated rotator cuff tear. Rabbits were used as subjects and classified into 2 groups: group A, right side, the layer-by-layer repair group; and group B, left side, the whole-layer repair group. Histologic evaluations were done at 3 weeks (n = 7) and 6 weeks (n = 4) after operation. Biomechanical tests to evaluate the tensile property were done at time 0 (n = 5) and 3 weeks (n = 5) after operation. Histologic healing improved in all groups. A smaller cleft was found between layers in group B compared with the cleft in group A at 3 weeks after operation. At time 0, group A showed a higher yield load and ultimate failure load (67 ± 10.5 N and 80 ± 7.8 N, respectively). However, at 3 weeks after operation, group B showed a higher yield load (48 ± 7.6 N). In the delaminated rotator cuff tear model in the rabbit, the whole-layer repair showed a narrow gap between layers and a higher yield load at 3 weeks after operation. Surgical techniques that unite the cleft in a delaminated tear could improve biomechanical strength after operation. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  2. The ‘Sticky Elastica’: delamination blisters beyond small deformations

    KAUST Repository

    Wagner, Till J. W.

    2013-01-01

    We consider the form of an elastic loop adhered to a rigid substrate: the \\'Sticky Elastica\\'. In contrast to previous studies of the shape of delamination \\'blisters\\', the theory developed accounts for deflections with large slope (i.e. geometrically nonlinear). Starting from the classical Euler Elastica we provide numerical results for the dimensions of such blisters for a variety of end-end confinements and develop asymptotic expressions that reproduce these results well, even up to the point of self-contact. Interestingly, we find that the width of such blisters does not grow monotonically with increased confinement. Our theoretical predictions are confirmed by simple desktop experiments and suggest a new method for the measurement of the elastocapillary length for deformations that cannot be considered small. We discuss the implications of our results for applications such as flexible electronics. © 2013 The Royal Society of Chemistry.

  3. Structural reliability assessment capability in NESSUS

    Science.gov (United States)

    Millwater, H.; Wu, Y.-T.

    1992-07-01

    The principal capabilities of NESSUS (Numerical Evaluation of Stochastic Structures Under Stress), an advanced computer code developed for probabilistic structural response analysis, are reviewed, and its structural reliability assessed. The code combines flexible structural modeling tools with advanced probabilistic algorithms in order to compute probabilistic structural response and resistance, component reliability and risk, and system reliability and risk. An illustrative numerical example is presented.

  4. Layered zinc hydroxide salts: Delamination, preferred orientation of hydroxide lamellae, and formation of ZnO nanodiscs

    Czech Academy of Sciences Publication Activity Database

    Demel, Jan; Pleštil, Josef; Bezdička, Petr; Janda, Pavel; Klementová, Mariana; Lang, Kamil

    2011-01-01

    Roč. 360, č. 2 (2011), s. 532-539 ISSN 0021-9797 R&D Projects: GA MŠk ME09058; GA ČR GAP207/10/1447 Institutional research plan: CEZ:AV0Z40320502; CEZ:AV0Z40500505; CEZ:AV0Z40400503 Keywords : layered zinc hydroxide * delamination * exfoliation * hydroxide layer * ZnO Subject RIV: CA - Inorganic Chemistry Impact factor: 3.070, year: 2011

  5. Reliability of measuring hip abductor strength following total knee arthroplasty using a hand-held dynamometer.

    Science.gov (United States)

    Schache, Margaret B; McClelland, Jodie A; Webster, Kate E

    2016-01-01

    To investigate the test-retest reliability of measuring hip abductor strength in patients with total knee arthroplasty (TKA) using a hand-held dynamometer (HHD) with two different types of resistance: belt and manual resistance. Test-retest reliability of 30 subjects (17 female, 13 male, 71.9 ± 7.4 years old), 9.2 ± 2.7 days post TKA was measured using belt and therapist resistance. Retest reliability was calculated with intra-class coefficients (ICC3,1) and 95% confidence intervals (CI) for both the group average and the individual scores. A paired t-test assessed whether a difference existed between the belt and therapist methods of resistance. ICCs were 0.82 and 0.80 for the belt and therapist resisted methods, respectively. Hip abductor strength increases of 8 N (14%) for belt resisted and 14 N (17%) for therapist resisted measurements of the group average exceeded the 95% CI and may represent real change. For individuals, hip abductor strength increases of 33 N (72%) (belt resisted) and 57 N (79%) (therapist resisted) could be interpreted as real change. Hip abductor strength can be reliably measured using HHD in the clinical setting with the described protocol. Belt resistance demonstrated slightly higher test-retest reliability. Reliable measurement of hip abductor muscle strength in patients with TKA is important to ensure deficiencies are addressed in rehabilitation programs and function is maximized. Hip abductor strength can be reliably measured with a hand-held dynamometer in the clinical setting using manual or belt resistance.

  6. Novel method of assessing delamination of the anterior lens capsule using spectral-domain optical coherence tomography

    OpenAIRE

    Tan, Deborah KL; Aung, Tin; Perera, Shamira A

    2012-01-01

    Deborah KL Tan,1 Tin Aung,1–3 Shamira A Perera1,21Singapore National Eye Centre, Singapore; 2Singapore Eye Research Institute, Singapore; 3National University of Singapore, Yong Loo Lin School of Medicine, SingaporeBackground: Delamination of the anterior lens capsule producing a double-ring sign during continuous curvilinear capsulorhexis is commonly associated with true exfoliation syndrome.Methods: Previous studies have concentrated on light- and transmission-electron microscopic...

  7. Analysis of time-dependent reliability of degenerated reinforced concrete structure

    Directory of Open Access Journals (Sweden)

    Zhang Hongping

    2016-07-01

    Full Text Available Durability deterioration of structure is a highly random process. The maintenance of degenerated structure involves the calculation of the reliability of time-dependent structure. This study introduced reinforced concrete structure resistance decrease model and related statistical parameters of uncertainty, analyzed resistance decrease rules of corroded bending element of reinforced concrete structure, and finally calculated timedependent reliability of the corroded bending element of reinforced concrete structure, aiming to provide a specific theoretical basis for the application of time-dependent reliability theory.

  8. MODELLING THE DELAMINATION FAILURE ALONG THE CFRP-CFST BEAM INTERACTION SURFACE USING DIFFERENT FINITE ELEMENT TECHNIQUES

    Directory of Open Access Journals (Sweden)

    AHMED W. AL-ZAND

    2017-01-01

    Full Text Available Nonlinear finite element (FE models are prepared to investigate the behaviour of concrete-filled steel tube (CFST beams strengthened by carbon fibre reinforced polymer (CFRP sheets. The beams are strengthened from the bottom side only by varied sheet lengths (full and partial beam lengths and then subjected to ultimate flexural loads. Three surface interaction techniques are used to implement the bonding behaviour between the steel tube and the CFRP sheet, namely, full tie interaction (TI, cohesive element (CE and cohesive behaviour (CB techniques using ABAQUS software. Results of the comparison between the FE analysis and existing experimental study confirm that the FE models with the TI technique could be applicable for beams strengthened by CFRP sheets with a full wrapping length; the technique could not accurately implement the CFRP delamination failure, which occurred for beams with a partial wrapping length. Meanwhile, the FE models with the CE and CB techniques are applicable in the implementation of both CFRP failures (rapture and delamination for both full and partial wrapping lengths, respectively. Where, the ultimate loads' ratios achieved by the FE models using TI, CE and CB techniques about 1.122, 1.047 and 1.045, respectively, comparing to the results of existing experimental tests.

  9. Detection of Delamination in Laminate Wind Turbine Blades Using One-Dimensional Wavelet Analysis of Modal Responses

    Directory of Open Access Journals (Sweden)

    Łukasz Doliński

    2018-01-01

    Full Text Available This paper demonstrates the effectiveness of a nondestructive diagnostic technique used to determine the location and size of delamination in laminated coatings of wind turbine blades. This is realized based on results of numerical and experimental investigations obtained by the use of the finite element method (FEM and laser scanning vibrometry (LSV. The proposed method is based on the one-dimensional continuous wavelet transform of vibration parameters of a wind turbine blade. The investigations were conducted for a 1 : 10 scaled-down blade of a 36 m rotor wind turbine. Glass fibres and epoxy resin were used as laminate components. For numerical studies, a simple delamination model was proposed. The results obtained by the authors were used to determine the optimal set of parameters of the continuous wavelet transform. The application of high-quality LSV for experimental measurements allowed determining the optimal conditions of measuring procedures. At the same time the capabilities and limitations, resulting from the nature of the measurement method, were identified. In order to maximize the effectiveness of the detection method, preliminary signal processing was performed. Beside base wavelets also different waveform families were tested. The results obtained by the authors showed that it is possible to identify and localize even relatively small damage.

  10. A fiber bridging model for fatigue delamination in composite materials

    International Nuclear Information System (INIS)

    Gregory, Jeremy R.; Spearing, S. Mark

    2004-01-01

    A fiber bridging model has been created to examine the effects of bridging on Mode I delamination fatigue fracture in a carbon fiber polymer-matrix composite. The model uses a cohesive zone law that is derived from quasi-static R-curves to determine the bridging energy applied in the bridged region. Timoshenko beam theory and an iterative self-consistent scheme are used to calculate the bridging tractions and displacements. After applying the bridging model to crack propagation data the scatter in the data was significantly reduced and clear trends were observed as a function of temperature that were not apparent previously. This indicated that the model appropriately accounted for the bridging in the experiments. Scanning electron microscopy crack opening displacement measurements were performed to validate the model's predictions. The measurements showed that the predictions were close to the actual bridging levels in the specimen

  11. Synthesis, anion exchange, and delamination of Co-Al layered double hydroxide: assembly of the exfoliated nanosheet/polyanion composite films and magneto-optical studies.

    Science.gov (United States)

    Liu, Zhaoping; Ma, Renzhi; Osada, Minoru; Iyi, Nobuo; Ebina, Yasuo; Takada, Kazunori; Sasaki, Takayoshi

    2006-04-12

    This paper describes a systematic study on the synthesis, anion exchange, and delamination of Co-Al layered double hydroxide (LDH), with the aim of achieving fabrication and clarifying the properties of LDH nanosheet/polyanion composite films. Co-Al-CO3 LDH hexagonal platelets of 4 mum in lateral size were synthesized by the urea method under optimized reaction conditions. The as-prepared CO3(2-)-LDH was converted to Cl- -LDH by treating with a NaCl-HCl mixed solution, retaining its high crystallinity and hexagonal platelike morphology. LDHs intercalated with a variety of anions (such as NO3-, ClO4-, acetate, lactate, dodecyl sulfate, and oleate) were further prepared from Cl- -LDH via an anion-exchange process employing corresponding salts. Exchanged products in various anion forms were found to show different delamination behaviors in formamide. Among them, best results were observed for NO3- -LDH in terms of the exfoliating degree and the quality of the exfoliated nanosheets. The delamination gave a pink transparent suspension containing well-defined nanosheets with lateral sizes of up to 2 microm. The resulting nanosheets were assembled layer-by-layer with an anionic polymer, poly(sodium styrene 4-sulfonate) (PSS), onto quartz glass substrates to produce composite films. Magnetic circular dichroism (MCD) measurements revealed that the assembled multilayer films exhibited an interesting magneto-optical response.

  12. The effect of Al intermediate layer on thermal resistance of EB-PVD yttria-stabilized zirconia coatings on titanium substrate

    Science.gov (United States)

    Panin, Alexey; Panin, Victor; Kazachenok, Marina; Shugurov, Artur; Sinyakova, Elena; Martynov, Sergey; Rusyaev, Andrey; Kasterov, Artur

    2017-12-01

    The yttria-stabilized zirconia coatings sprayed on titanium substrates by the electron beam physical vapor deposition were subjected to thermal annealing in air at 1000°C for 1, 30 and 60 min. The delamination and fracture of the coatings are studied by the scanning electron microscopy and X-ray diffraction. It is shown that a magnetron sputtered Al interlayer between the coating and the substrate considerably improves the thermal resistance of ceramic coatings.

  13. The Effect of Epoxy Molding Compound Floor Life to Reliability Performance and mold ability for QFN Package

    Science.gov (United States)

    Peanpunga, Udom; Ugsornrat, Kessararat; Thorlor, Panakamol; Sumithpibul, Chalermsak

    2017-09-01

    This research studied about an epoxy molding compound (EMC) floor life to reliability performance of integrated circuit (IC) package. Molding is the process for protecting the die of IC package form mechanical and chemical reaction from external environment by shaping EMC. From normal manufacturing process, the EMC is stored in the frozen at 5oC and left at around room temperature for aging time or floor life before molding process. The EMC floor life effect to its properties and reliability performance of IC package. Therefore, this work interested in varied the floor life of EMC before molding process to analyze properties of EMC such as spiral flow length, gelation time, and viscosity. In experiment, the floor life of EMC was varied to check the effect of its property to reliability performance. The EMC floor life were varied from 0 hours to 60 hours with a step of 12 hours and observed wire sweep, incomplete EMC, and delamination inside the packages for 3x3, 5x5 and 8x8 mm2 of QFN packages. The evaluation showed about clearly effect of EMC floor life to IC packaging reliability. EMC floor life is not any concern for EMC property, moldabilty, and reliability from 0 hours to 48 hours for molding process of 3x3,5x5 and 8x8 mm2 QFN packaging manufacturing

  14. Implementing statistical analysis in multi-channel acoustic impact-echo testing of concrete bridge decks: Determining thresholds for delamination detection

    Science.gov (United States)

    Hendricks, Lorin; Spencer Guthrie, W.; Mazzeo, Brian

    2018-04-01

    An automated acoustic impact-echo testing device with seven channels has been developed for faster surveying of bridge decks. Due to potential variations in bridge deck overlay thickness, varying conditions between testing passes, and occasional imprecise equipment calibrations, a method that can account for variations in deck properties and testing conditions was necessary to correctly interpret the acoustic data. A new methodology involving statistical analyses was therefore developed. After acoustic impact-echo data are collected and analyzed, the results are normalized by the median for each channel, a Gaussian distribution is fit to the histogram of the data, and the Kullback-Leibler divergence test or Otsu's method is then used to determine the optimum threshold for differentiating between intact and delaminated concrete. The new methodology was successfully applied to individual channels of previously unusable acoustic impact-echo data obtained from a three-lane interstate bridge deck surfaced with a polymer overlay, and the resulting delamination map compared very favorably with the results of a manual deck sounding survey.

  15. Reliability and construction control

    Directory of Open Access Journals (Sweden)

    Sherif S. AbdelSalam

    2016-06-01

    Full Text Available The goal of this study was to determine the most reliable and efficient combination of design and construction methods required for vibro piles. For a wide range of static and dynamic formulas, the reliability-based resistance factors were calculated using EGYPT database, which houses load test results for 318 piles. The analysis was extended to introduce a construction control factor that determines the variation between the pile nominal capacities calculated using static versus dynamic formulae. From the major outcomes, the lowest coefficient of variation is associated with Davisson’s criterion, and the resistance factors calculated for the AASHTO method are relatively high compared with other methods. Additionally, the CPT-Nottingham and Schmertmann method provided the most economic design. Recommendations related to a pile construction control factor were also presented, and it was found that utilizing the factor can significantly reduce variations between calculated and actual capacities.

  16. A combined experimental and theoretical approach to establish the relationship between shear force and clay platelet delamination in melt-processed polypropylene nanocomposites

    CSIR Research Space (South Africa)

    Bandyopadhyay, J

    2014-04-01

    Full Text Available In this article, a combined experimental and theoretical approach has been proposed to establish a relationship between the required shear force and the degree of delamination of clay tactoids during the melt-processing of polymer nanocomposites...

  17. Reliability of thermal interface materials: A review

    International Nuclear Information System (INIS)

    Due, Jens; Robinson, Anthony J.

    2013-01-01

    Thermal interface materials (TIMs) are used extensively to improve thermal conduction across two mating parts. They are particularly crucial in electronics thermal management since excessive junction-to-ambient thermal resistances can cause elevated temperatures which can negatively influence device performance and reliability. Of particular interest to electronic package designers is the thermal resistance of the TIM layer at the end of its design life. Estimations of this allow the package to be designed to perform adequately over its entire useful life. To this end, TIM reliability studies have been performed using accelerated stress tests. This paper reviews the body of work which has been performed on TIM reliability. It focuses on the various test methodologies with commentary on the results which have been obtained for the different TIM materials. Based on the information available in the open literature, a test procedure is proposed for TIM selection based on beginning and end of life performance. - Highlights: ► This paper reviews the body of work which has been performed on TIM reliability. ► Test methodologies for reliability testing are outlined. ► Reliability results for the different TIM materials are discussed. ► A test procedure is proposed for TIM selection BOLife and EOLife performance.

  18. Partial delamination of continental mantle lithosphere, uplift-related crust mantle decoupling, volcanism and basin formation: a new model for the Pliocene Quaternary evolution of the southern East-Carpathians, Romania

    Science.gov (United States)

    Chalot-Prat, F.; Girbacea, R.

    2000-11-01

    A geodynamic model is proposed for the Mid-Miocene to Quaternary evolution of the southern East-Carpathians in order to explain the relationships between shallow and deep geological phenomena that occurred synchronously during late-collision tectonics. In this area, an active volcanic zone cross-cuts since 2 My the suture between the overriding Tisza-Dacia and subducting European continental plates. Mafic calc-alkaline and alkaline magmas (south Harghita and Persani volcanoes) erupted contemporaneously. These magmas were supplied by partial melting of the mantle lithosphere of the subducting, and not of the overriding, plate. In an effort to decipher this geodynamically a-typical setting of magma generation, the spatial and temporal distribution of shallow and deep phenomena was successively examined in order to establish the degree of their interdependence. Our model indicates that intra-mantle delamination of the subducting European plate is the principal cause of a succession of events. It caused upwelling of the hot asthenosphere below a thinned continental lithosphere of the Carpathians, inducing the uplift of the lithosphere and its internal decoupling at the Moho level by isostatic and mostly thermal effects. During this uplift, the crust deformed flexurally whilst the mantle deformed in a ductile way. This triggered decompressional partial melting of the uppermost mantle lithosphere. Flexural deformation of the crust induced its fracturing, allowing for the rapid ascent of magmas to the surface, as well as reactivation of an older detachment horizon at the base of the Carpathian nappe stack above which the Brasov, Ciuc and Gheorghieni hinterland basins formed by extension and gravity spreading. The rapid subsidence of the Focsani foreland basin is controlled by the load exerted on the lithosphere by the delaminated mantle slab that is still attached to it. In this model, crust-mantle decoupling, magma genesis and volcanism, local near-surface hinterland

  19. Thermal shock resistances of a bonding material of C/C composite and copper

    International Nuclear Information System (INIS)

    Kurumada, Akira; Oku, Tatsuo; Kawamata, Kiyohiro; Motojima, Osamu; Noda, Nobuaki; McEnaney, B.

    1997-01-01

    The purpose of this study is to contribute to the development and the safety design of plasma facing components for fusion reactor devices. We evaluated the thermal shock resistance and the thermal shock fracture toughness of a bonding material which was jointed a carbon-fiber-reinforced carbon composite (C/C composite) to oxygen-free copper. We also examined the microstructures of the bonding layers using a scanning electron microscope before and after thermal shock tests. The bonding material did not fracture during thermal shock tests. However, thermal cracks and delamination cracks were observed in the bonding layers. (author)

  20. INCREASED RELIABILITY OF ELECTRIC BLASTING

    OpenAIRE

    Kashuba, Oleh Ivanovych; Skliarov, L I; Skliarov, A L

    2017-01-01

    The problems of improving reliability of an electric blasting method using electric detonators with nichrome filament bridges. It was revealed that in the calculation of the total resistance of the explosive network it is necessary to increase to 24% of the nominal value

  1. How reliable are national surveillance data? Findings from an audit of Canadian methicillin-resistant Staphylococcus aureus surveillance data.

    Science.gov (United States)

    Forrester, Leslie; Collet, Jun Chen; Mitchell, Robyn; Pelude, Linda; Henderson, Elizabeth; Vayalumkal, Joseph; Leduc, Stephanie; Ghahreman, Saeed; Weir, Christine; Gravel, Denise

    2012-03-01

    The Canadian Nosocomial Infection Surveillance Program (CNISP) has conducted surveillance for incident cases of methicillin-resistant Staphylococcus aureus (MRSA) in sentinel hospitals since 1995. In 2007, a reliability audit of the 2005 data was conducted. In 2005, 5,652 cases were submitted to the CNISP from 43 hospitals. A proportional sample of submitted forms (up to 25) from each site were randomly selected. Stratified random sampling was used to obtain the comparison data. The original data were compared with the reabstracted data for congruence on 7 preselected variables. Reabstracted data were received from 30 out of 43 hospitals (70%), providing 443 of the 598 case forms requested (74%). Of these, 397 (90%) had matching case identification numbers. Overall, the percentage of discordant responses was 7.0%, ranging from 3.5% for sex and up to 23.7% for less well-defined variables (eg, where MRSA was acquired). Our findings suggest that, in general, the 2005 MRSA data are reliable. However to improve reliability a data quality framework with quality assurance practices, including ongoing auditing should be integrated into the CNISP's surveillance programs. Providing training to data collectors and standard definitions with practical examples may help to improve data quality, especially for those variables that require clinical judgment. Crown Copyright © 2012. Published by Mosby, Inc. All rights reserved.

  2. Oxidation resistance of TiN, CrN, TiAlN and CrAlN coatings deposited by lateral rotating cathode arc

    International Nuclear Information System (INIS)

    Chim, Y.C.; Ding, X.Z.; Zeng, X.T.; Zhang, S.

    2009-01-01

    In this paper, four kinds of hard coatings, TiN, CrN, TiAlN and CrAlN (with Al/Ti or Al/Cr atomic ratio around 1:1), were deposited on stainless steel substrates by a lateral rotating cathode arc technique. The as-deposited coatings were annealed in ambient atmosphere at different temperatures (500-1000 o C) for 1 h. The evolution of chemical composition, microstructure, and microhardness of these coatings after annealing at different temperatures was systematically analyzed by energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and nanoindentation experiments. The oxidation behaviour and its influence on overall hardness of these four coatings were compared. It was found that the ternary TiAlN and CrAlN coatings have better oxidation resistance than their binary counterparts, TiN and CrN coatings. The Cr-based coatings (CrN and CrAlN) exhibited evidently better oxidation resistance than the Ti-based coatings (TiN and TiAlN). TiN coating started to oxidize at 500 o C. After annealing at 700 o C no N could be detected by EDX, indicating that the coating was almost fully oxidized. After annealed at 800 o C, the coating completely delaminated from the substrate. TiAlN started to oxidize at 600 o C. It was nearly fully oxidized (with little residual nitrogen detected in the coating by EDX) and partially delaminated at 1000 o C. Both CrN and CrAlN started to oxidize at 700 o C. CrN was almost fully oxidized (with little residual nitrogen detected in the coating by EDX) and partially delaminated at 900 o C. The oxidation rate of the CrAlN coating is quite slow. After annealing at 1000 o C, only about 19 at.% oxygen was detected and the coating showed no delamination. The Ti-based (TiN and TiAlN) coatings were not able to retain their hardness at higher temperatures (≥ 700 o C). On the other hand, the hardness of CrAlN was stable at a high level between 33 and 35 GPa up to an annealing temperature of 800 o C and still kept at a comparative high value of

  3. Reliability and Validity Assessment of a Linear Position Transducer

    Science.gov (United States)

    Garnacho-Castaño, Manuel V.; López-Lastra, Silvia; Maté-Muñoz, José L.

    2015-01-01

    The objectives of the study were to determine the validity and reliability of peak velocity (PV), average velocity (AV), peak power (PP) and average power (AP) measurements were made using a linear position transducer. Validity was assessed by comparing measurements simultaneously obtained using the Tendo Weightlifting Analyzer Systemi and T-Force Dynamic Measurement Systemr (Ergotech, Murcia, Spain) during two resistance exercises, bench press (BP) and full back squat (BS), performed by 71 trained male subjects. For the reliability study, a further 32 men completed both lifts using the Tendo Weightlifting Analyzer Systemz in two identical testing sessions one week apart (session 1 vs. session 2). Intraclass correlation coefficients (ICCs) indicating the validity of the Tendo Weightlifting Analyzer Systemi were high, with values ranging from 0.853 to 0.989. Systematic biases and random errors were low to moderate for almost all variables, being higher in the case of PP (bias ±157.56 W; error ±131.84 W). Proportional biases were identified for almost all variables. Test-retest reliability was strong with ICCs ranging from 0.922 to 0.988. Reliability results also showed minimal systematic biases and random errors, which were only significant for PP (bias -19.19 W; error ±67.57 W). Only PV recorded in the BS showed no significant proportional bias. The Tendo Weightlifting Analyzer Systemi emerged as a reliable system for measuring movement velocity and estimating power in resistance exercises. The low biases and random errors observed here (mainly AV, AP) make this device a useful tool for monitoring resistance training. Key points This study determined the validity and reliability of peak velocity, average velocity, peak power and average power measurements made using a linear position transducer The Tendo Weight-lifting Analyzer Systemi emerged as a reliable system for measuring movement velocity and power. PMID:25729300

  4. Effect of a hard coat layer on buckle delamination of thin ITO layers on a compliant elasto-plastic substrate: an experimental–numerical approach

    NARCIS (Netherlands)

    Sluis, van der O.; Abdallah, Amir; Bouten, P.C.P.; Timmermans, P.H.M.; Toonder, den J.M.J.; With, de G.

    2011-01-01

    Layer buckling and delamination is a common interfacial failure phenomenon in thin film multi-layer structures that are used in flexible display applications. Typically, the substrate is coated on both sides with a hybrid coating, calleda hard coat (HC), which acts as a gas barrier and also

  5. Insulin resistance in obesity can be reliably identified from fasting plasma insulin

    NARCIS (Netherlands)

    ter Horst, K. W.; Gilijamse, P. W.; Koopman, K. E.; de Weijer, B. A.; Brands, M.; Kootte, R. S.; Romijn, J. A.; Ackermans, M. T.; Nieuwdorp, M.; Soeters, M. R.; Serlie, M. J.

    2015-01-01

    Insulin resistance is the major contributor to cardiometabolic complications of obesity. We aimed to (1) establish cutoff points for insulin resistance from euglycemic hyperinsulinemic clamps (EHCs), (2) identify insulin-resistant obese subjects and (3) predict insulin resistance from routinely

  6. Enhancement of low temperature toughness of nanoprecipitates strengthened ferritic steel by delamination structure

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yu; Xu, Songsong; Li, Junpeng; Zhang, Jian [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, P R China (China); Sun, Liangwei; Chen, Liang; Sun, Guangai; Peng, Shuming [Key Laboratory of Neutron Physics and Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics (CAEP), Mianyang 621999 (China); Zhang, Zhongwu, E-mail: zwzhang@hrbeu.edu.cn [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, P R China (China)

    2017-04-13

    This study investigated the effects of aging and thermomechanical treatments on the microstructure evolution and mechanical properties of a nanoprecipitates strengthened ferritic steel. The toughness of steel at various temperatures was measured carefully and correlated with microstructural features. Tensile tests show that aging can improve the mechanical strength without scarifying the ductility. With high yield strength of ~1000 MPa, excellent low temperature Charpy impact energy more than 300 J at −80 °C can be obtained. The ductile brittle transition temperature (DBTT) is lower than −80 °C. The high strength can be contributed by the nanocluster precipitation as determined by small angle neutron scattering and transmission electron microscopy. The excellent low temperature toughness is attributed to the delamination structure of the steel, which blunts the cracks and restrains the crack propagation.

  7. Thermal Performance and Reliability Characterization of Bonded Interface Materials (BIMs): Preprint

    Energy Technology Data Exchange (ETDEWEB)

    DeVoto, D.; Paret, P.; Mihalic, M.; Narumanchi, S.; Bar-Cohen, A.; Matin, K.

    2014-08-01

    Thermal interface materials are an important enabler for low thermal resistance and reliable electronics packaging for a wide array of applications. There is a trend towards bonded interface materials (BIMs) because of their potential for low thermal resistivity (< 1 mm2K/W). However, BIMs induce thermomechanical stresses in the package and can be prone to failures and integrity risks. Deteriorated interfaces can result in high thermal resistance in the package and degradation and/or failure of the electronics. DARPA's Thermal Management Technologies program has addressed this challenge, supporting the development of mechanically-compliant, low resistivity nano-thermal interface (NTI) materials. In this work, we describe the testing procedure and report the results of NREL's thermal performance and reliability characterization of an initial sample of four different NTI-BIMs.

  8. Reliability and Validity Assessment of a Linear Position Transducer

    Directory of Open Access Journals (Sweden)

    Manuel V. Garnacho-Castaño

    2015-03-01

    Full Text Available The objectives of the study were to determine the validity and reliability of peak velocity (PV, average velocity (AV, peak power (PP and average power (AP measurements were made using a linear position transducer. Validity was assessed by comparing measurements simultaneously obtained using the Tendo Weightlifting Analyzer Systemi and T-Force Dynamic Measurement Systemr (Ergotech, Murcia, Spain during two resistance exercises, bench press (BP and full back squat (BS, performed by 71 trained male subjects. For the reliability study, a further 32 men completed both lifts using the Tendo Weightlifting Analyzer Systemz in two identical testing sessions one week apart (session 1 vs. session 2. Intraclass correlation coefficients (ICCs indicating the validity of the Tendo Weightlifting Analyzer Systemi were high, with values ranging from 0.853 to 0.989. Systematic biases and random errors were low to moderate for almost all variables, being higher in the case of PP (bias ±157.56 W; error ±131.84 W. Proportional biases were identified for almost all variables. Test-retest reliability was strong with ICCs ranging from 0.922 to 0.988. Reliability results also showed minimal systematic biases and random errors, which were only significant for PP (bias -19.19 W; error ±67.57 W. Only PV recorded in the BS showed no significant proportional bias. The Tendo Weightlifting Analyzer Systemi emerged as a reliable system for measuring movement velocity and estimating power in resistance exercises. The low biases and random errors observed here (mainly AV, AP make this device a useful tool for monitoring resistance training.

  9. Mechanical reliability analysis of tubes intended for hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Nahal, Mourad; Khelif, Rabia [Badji Mokhtar University, Annaba (Algeria)

    2013-02-15

    Reliability analysis constitutes an essential phase in any study concerning reliability. Many industrialists evaluate and improve the reliability of their products during the development cycle - from design to startup (design, manufacture, and exploitation) - to develop their knowledge on cost/reliability ratio and to control sources of failure. In this study, we obtain results for hardness, tensile, and hydrostatic tests carried out on steel tubes for transporting hydrocarbons followed by statistical analysis. Results obtained allow us to conduct a reliability study based on resistance request. Thus, index of reliability is calculated and the importance of the variables related to the tube is presented. Reliability-based assessment of residual stress effects is applied to underground pipelines under a roadway, with and without active corrosion. Residual stress has been found to greatly increase probability of failure, especially in the early stages of pipe lifetime.

  10. [Clinical research of arthroscopic separate double-layer suture bridge technique for delaminated rotator cuff tear].

    Science.gov (United States)

    Ren, Jiangtao; Xu, Cong; Liu, Xianglin; Wang, Jiansong; Li, Zhihuai; Lü, Yongming

    2017-10-01

    To explore the effectiveness of the arthroscopic separate double-layer suture bridge technique in treatment of the delaminated rotator cuff tear. Between May 2013 and May 2015, 54 patients with the delaminated rotator cuff tears were recruited in the study. They were randomly allocated into 2 groups to receive repair either using arthroscopic separate double-layer suture bridge technique (trial group, n =28) or using arthroscopic whole-layer suture bridge technique (control group, n =26). There was no significant difference in gender, age, injured side, tear type, and preoperative visual analogue scale (VAS) score, Constants score, American Shoulder and Elbow Surgeons (ASES) score, University of California Los Angeles (UCLA) score, and the range of motion of shoulder joint between 2 groups ( P >0.05). Postoperative functional scores, range of motion, and recurrence rate of tear in 2 groups were observed and compared. The operation time was significant longer in trial group than in control group ( t =8.383, P =0.000). All incisions healed at stage Ⅰ without postoperative complication. All the patients were followed up 12 months. At 12 months postoperatively, the UCLA score, ASES score, VAS score, Constant score, and the range of motion were significantly improved when compared with the preoperative values in 2 groups ( P 0.05). Four cases (14.3%) of rotator cuff tear recurred in trial group while 5 cases (19.2%) in control group, showing no significant difference ( χ 2 =0.237, P =0.626). Compared with the arthroscopic whole-layer suture bridge technique, arthroscopic separate double-layer suture bridge technique presents no significant difference in the shoulder function score, the range of motion, and recurrence of rotator cuff tear, while having a longer operation time.

  11. Thermal Shock Resistance of Stabilized Zirconia/Metal Coat on Polymer Matrix Composites by Thermal Spraying Process

    Science.gov (United States)

    Zhu, Ling; Huang, Wenzhi; Cheng, Haifeng; Cao, Xueqiang

    2014-12-01

    Stabilized zirconia/metal coating systems were deposited on the polymer matrix composites by a combined thermal spray process. Effects of the thicknesses of metal layers and ceramic layer on thermal shock resistance of the coating systems were investigated. According to the results of thermal shock lifetime, the coating system consisting of 20 μm Zn and 125 μm 8YSZ exhibited the best thermal shock resistance. Based on microstructure evolution, failure modes and failure mechanism of the coating systems were proposed. The main failure modes were the formation of vertical cracks and delamination in the outlayer of substrate, and the appearance of coating spallation. The residual stress, thermal stress and oxidation of substrate near the substrate/metal layer interface were responsible for coating failure, while the oxidation of substrate near the substrate/coating interface was the dominant one.

  12. Gamma processes and peaks-over-threshold distributions for time-dependent reliability

    International Nuclear Information System (INIS)

    Noortwijk, J.M. van; Weide, J.A.M. van der; Kallen, M.J.; Pandey, M.D.

    2007-01-01

    In the evaluation of structural reliability, a failure is defined as the event in which stress exceeds a resistance that is liable to deterioration. This paper presents a method to combine the two stochastic processes of deteriorating resistance and fluctuating load for computing the time-dependent reliability of a structural component. The deterioration process is modelled as a gamma process, which is a stochastic process with independent non-negative increments having a gamma distribution with identical scale parameter. The stochastic process of loads is generated by a Poisson process. The variability of the random loads is modelled by a peaks-over-threshold distribution (such as the generalised Pareto distribution). These stochastic processes of deterioration and load are combined to evaluate the time-dependent reliability

  13. Microscopic mapping of specific contact resistances and long-term reliability tests on 4H-silicon carbide using sputtered titanium tungsten contacts for high temperature device applications

    Science.gov (United States)

    Lee, S.-K.; Zetterling, C.-M.; Ostling, M.

    2002-07-01

    We report on the microscopic mapping of specific contact resistances (rhoc) and long-term reliability tests using sputtered titanium tungsten (TiW) ohmic contacts to highly doped n-type epilayers of 4H-silicon carbide. The TiW ohmic contacts showed good uniformity with low contact resistivity of 3.3 x10-5 Omega cm2. Microscopic mapping of the rhoc showed that the rhoc had a distribution that decreased from the center to the edge of the wafer. This distribution of the rhoc is caused by variation of the doping concentration of the wafer. Sacrificial oxidation at high temperature partially recovered inductively coupled plasma etch damage. TiW contacts with platinum and gold capping layers have stable specific contact resistance at 500 and 600 degC in a vacuum chamber for 308 h.

  14. Delamination-restacking behaviour of surfactant intercalated layered hydroxy double salts, M 3Zn 2(OH) 8(surf) 2ṡ2H 2O [M = Ni, Co and surf = dodecyl sulphate (DS), dodecyl benzene sulphonate (DBS)

    Science.gov (United States)

    Rajamathi, Jacqueline T.; Ravishankar, N.; Rajamathi, Michael

    2005-02-01

    Surfactant anion intercalated nickel-zinc and cobalt-zinc layered hydroxy double salts were prepared through a modified acetate hydrolysis route. These organo-inorganic hybrids delaminate readily in alcohols such as 1-butanol to give stable translucent colloids. The extent of delamination and the stability of the colloids obtained are comparable to what has been observed in the case of layered double hydroxides (LDHs). The original layered solid could be obtained either by evaporation of the colloid or precipitation by the addition of a polar solvent such as acetone.

  15. Metal-etching-free direct delamination and transfer of single-layer graphene with a high degree of freedom.

    Science.gov (United States)

    Yang, Sang Yoon; Oh, Joong Gun; Jung, Dae Yool; Choi, HongKyw; Yu, Chan Hak; Shin, Jongwoo; Choi, Choon-Gi; Cho, Byung Jin; Choi, Sung-Yool

    2015-01-14

    A method of graphene transfer without metal etching is developed to minimize the contamination of graphene in the transfer process and to endow the transfer process with a greater degree of freedom. The method involves direct delamination of single-layer graphene from a growth substrate, resulting in transferred graphene with nearly zero Dirac voltage due to the absence of residues that would originate from metal etching. Several demonstrations are also presented to show the high degree of freedom and the resulting versatility of this transfer method. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Improved concretes for corrosion resistance

    Science.gov (United States)

    1997-07-01

    The deterioration of various reinforced concrete bridge components containing conventional black steel reinforcement is the most important problem facing U.S. highway agencies. A major cause of this concrete deterioration (cracking, delamination, and...

  17. System reliability of corroding pipelines

    International Nuclear Information System (INIS)

    Zhou Wenxing

    2010-01-01

    A methodology is presented in this paper to evaluate the time-dependent system reliability of a pipeline segment that contains multiple active corrosion defects and is subjected to stochastic internal pressure loading. The pipeline segment is modeled as a series system with three distinctive failure modes due to corrosion, namely small leak, large leak and rupture. The internal pressure is characterized as a simple discrete stochastic process that consists of a sequence of independent and identically distributed random variables each acting over a period of one year. The magnitude of a given sequence follows the annual maximum pressure distribution. The methodology is illustrated through a hypothetical example. Furthermore, the impact of the spatial variability of the pressure loading and pipe resistances associated with different defects on the system reliability is investigated. The analysis results suggest that the spatial variability of pipe properties has a negligible impact on the system reliability. On the other hand, the spatial variability of the internal pressure, initial defect sizes and defect growth rates can have a significant impact on the system reliability.

  18. The Microstructures and Electrical Resistivity of (Al, Cr, TiFeCoNiOx High-Entropy Alloy Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    Chun-Huei Tsau

    2015-01-01

    Full Text Available The (Al, Cr, TiFeCoNi alloy thin films were deposited by PVD and using the equimolar targets with same compositions from the concept of high-entropy alloys. The thin films became metal oxide films after annealing at vacuum furnace for a period; and the resistivity of these thin films decreased sharply. After optimum annealing treatment, the lowest resistivity of the FeCoNiOx, CrFeCoNiOx, AlFeCoNiOx, and TiFeCoNiOx films was 22, 42, 18, and 35 μΩ-cm, respectively. This value is close to that of most of the metallic alloys. This phenomenon was caused by delaminating of the alloy oxide thin films because the oxidation was from the surfaces of the thin films. The low resistivity of these oxide films was contributed to the nonfully oxidized elements in the bottom layers and also vanishing of the defects during annealing.

  19. Re-assessing reliability based on survived loads

    NARCIS (Netherlands)

    Schweckendiek, T.

    2011-01-01

    The reliability of flood defenses is often dictated by large uncertainties in the hydraulic loading and the structural resistance. Additional information decreases uncertainty, however, acquiring it is often costly. One source of information, even though in many cases readily available, is hardly

  20. Understanding the mechanisms that change the conductivity of damaged ITO-coated polymeric films: A micro-mechanical investigation

    KAUST Repository

    Nasr Saleh, Mohamed

    2014-11-01

    Degradation from mechanical loading of transparent electrodes made of indium tin oxide (ITO) endangers the integrity of any material based on these electrodes, including flexible organic solar cells. However, how different schemes of degradation change the conductivity of ITO devices remains unclear. We propose a systematic micro-mechanics-based approach to clarify the relationship between degradation and changes in electrical resistance. By comparing experimentally measured channel crack densities to changes in electrical resistance returned by the different micro-mechanical schemes, we highlight the key role played by the residual conductivity in the interface between the ITO electrode and its substrate after delamination. We demonstrate that channel cracking alone does not explain the experimental observations. Our results indicate that delamination has to take place between the ITO electrode and the substrate layers and that the residual conductivity of this delaminated interface plays a major role in changes in electrical resistance of the degraded device. © 2014 Elsevier B.V.

  1. Determination of the influence of dispersion pattern of pesticide-resistant individuals on the reliability of resistance estimates using different sampling plans.

    Science.gov (United States)

    Shah, R; Worner, S P; Chapman, R B

    2012-10-01

    Pesticide resistance monitoring includes resistance detection and subsequent documentation/ measurement. Resistance detection would require at least one (≥1) resistant individual(s) to be present in a sample to initiate management strategies. Resistance documentation, on the other hand, would attempt to get an estimate of the entire population (≥90%) of the resistant individuals. A computer simulation model was used to compare the efficiency of simple random and systematic sampling plans to detect resistant individuals and to document their frequencies when the resistant individuals were randomly or patchily distributed. A patchy dispersion pattern of resistant individuals influenced the sampling efficiency of systematic sampling plans while the efficiency of random sampling was independent of such patchiness. When resistant individuals were randomly distributed, sample sizes required to detect at least one resistant individual (resistance detection) with a probability of 0.95 were 300 (1%) and 50 (10% and 20%); whereas, when resistant individuals were patchily distributed, using systematic sampling, sample sizes required for such detection were 6000 (1%), 600 (10%) and 300 (20%). Sample sizes of 900 and 400 would be required to detect ≥90% of resistant individuals (resistance documentation) with a probability of 0.95 when resistant individuals were randomly dispersed and present at a frequency of 10% and 20%, respectively; whereas, when resistant individuals were patchily distributed, using systematic sampling, a sample size of 3000 and 1500, respectively, was necessary. Small sample sizes either underestimated or overestimated the resistance frequency. A simple random sampling plan is, therefore, recommended for insecticide resistance detection and subsequent documentation.

  2. Reliability analysis of steel-containment strength

    International Nuclear Information System (INIS)

    Greimann, L.G.; Fanous, F.; Wold-Tinsae, A.; Ketalaar, D.; Lin, T.; Bluhm, D.

    1982-06-01

    A best estimate and uncertainty assessment of the resistance of the St. Lucie, Cherokee, Perry, WPPSS and Browns Ferry containment vessels was performed. The Monte Carlo simulation technique and second moment approach were compared as a means of calculating the probability distribution of the containment resistance. A uniform static internal pressure was used and strain ductility was taken as the failure criterion. Approximate methods were developed and calibrated with finite element analysis. Both approximate and finite element analyses were performed on the axisymmetric containment structure. An uncertainty assessment of the containment strength was then performed by the second moment reliability method. Based upon the approximate methods, the cumulative distribution for the resistance of each of the five containments (shell modes only) is presented

  3. Amphibole Fractional Crystallization and Delamination in Arc Roots: Implications for the `Missing' Nb Reservoir in the Earth

    Science.gov (United States)

    Galster, F.; Chatterjee, R. N.; Stockli, D. F.

    2017-12-01

    Most geologic processes should not fractionate Nb from Ta but Earth's major silicate reservoirs have subchondritic Nb/Ta values. Nb/Ta of >10000 basalts and basaltic andesites from different tectonic settings (GEOROC) cluster around 16, indistinguishable from upper mantle values. In contrast, Nb/Ta in more evolved arc volcanics have progressively lower values, reaching continental crust estimates, and correlate negatively with SiO2 (see figure) and positively with TiO2 and MgO. This global trend suggests that differentiation processes in magmatic arcs could explain bulk crustal Nb/Ta estimates. Understanding processes that govern fractionation of Nb from Ta in arcs can provide key insights on continental crust formation and help identify Earth's `missing' Nb reservoir. Ti-rich phases (rutile, titanite and ilmenite) have DNb/DTa values in the evolved liquid. Lack of correlation between Nb/Ta and K2O in global volcanic rocks implies that biotite plays a minor role in fractionating Nb from Ta during differentiation. Experimental petrology and evidence from exposed arc sections indicate that amphibole fractionation and delamination of island arc roots can explain the andesitic composition of bulk continental crust. Experimental studies have shown that amphibole Mg# correlate with DNb/DTa and amphibole could effectively fractionate Nb from Ta. Preliminary data from lower to middle crustal amphiboles from preserved arcs show sub- to super-chondritic Nb/Ta up to >60. This suggests that delamination of amphibole-rich cumulates can be a viable mechanism for the preferential removal of Nb from the continental crust. Future examination of Nb/Ta ratios in lower crustal amphiboles from various preserved arcs will provide improved constraints on the Nb-Ta paradox of the silicate Earth.

  4. Influence of boundary conditions on the response of multilayered plates with cohesive interfaces and delaminations using a homogenized approach

    Directory of Open Access Journals (Sweden)

    R. Massabò

    2014-07-01

    Full Text Available Stress and displacement fields in multilayered composites with interfacial imperfections, such as imperfect bonding of the layers or delaminations, or where the plies are separated by thin interlayers allowing relative motion, have large variations in the thickness, with characteristic zigzag patterns and jumps at the layer interfaces. These effects are well captured by a model recently formulated by the author for multilayered plates with imperfect interfaces and affine interfacial traction laws (Massabò & Campi, Meccanica, 2014, in press; Compos Struct, 2014, 116, 311-324. The model defines a homogenized displacement field, which satisfies interfacial continuity, and uses a variational technique to derive equilibrium equations depending on only six generalized displacement functions, for any arbitrary numbers of layers and interfaces. The model accurately predicts stresses and displacements in simply supported, highly anisotropic, thick plates with continuous, sliding interfaces. In this paper the model is applied to wide plates with clamped edges and some inconsistencies, which have been noted in the literature for models based on similar approaches and have limited their utilization, are explained. A generalized transverse shear force is introduced as the gross stress resultant which is directly related to the bending moment in the equilibrium equations of multilayered structures with imperfect interfaces and substitutes for the shear force of single-layer theory. An application to a delaminated wide plate highlights the potential and limitations of the proposed model for the solution of fracture mechanics problems.

  5. Test-Retest Reliability of Rating of Perceived Exertion and Agreement With 1-Repetition Maximum in Adults.

    Science.gov (United States)

    Bove, Allyn M; Lynch, Andrew D; DePaul, Samantha M; Terhorst, Lauren; Irrgang, James J; Fitzgerald, G Kelley

    2016-09-01

    Study Design Clinical measurement. Background It has been suggested that rating of perceived exertion (RPE) may be a useful alternative to 1-repetition maximum (1RM) to determine proper resistance exercise dosage. However, the test-retest reliability of RPE for resistance exercise has not been determined. Additionally, prior research regarding the relationship between 1RM and RPE is conflicting. Objectives The purpose of this study was to (1) determine test-retest reliability of RPE related to resistance exercise and (2) assess agreement between percentages of 1RM and RPE during quadriceps resistance exercise. Methods A sample of participants with and without knee pathology completed a series of knee extension exercises and rated the perceived difficulty of each exercise on a 0-to-10 RPE scale, then repeated the procedure 1 to 2 weeks later for test-retest reliability. To determine agreement between RPE and 1RM, participants completed knee extension exercises at various percentages of their 1RM (10% to 130% of predicted 1RM) and rated the perceived difficulty of each exercise on a 0-to-10 RPE scale. Percent agreement was calculated between the 1RM and RPE at each resistance interval. Results The intraclass correlation coefficient indicated excellent test-retest reliability of RPE for quadriceps resistance exercises (intraclass correlation coefficient = 0.895; 95% confidence interval: 0.866, 0.918). Overall percent agreement between RPE and 1RM was 60%, but agreement was poor within the ranges that would typically be used for training (50% 1RM for muscle endurance, 70% 1RM and greater for strength). Conclusion Test-retest reliability of perceived exertion during quadriceps resistance exercise was excellent. However, agreement between the RPE and 1RM was poor, especially in common training zones for knee extensor strengthening. J Orthop Sports Phys Ther 2016;46(9):768-774. Epub 5 Aug 2016. doi:10.2519/jospt.2016.6498.

  6. An overview on the origin of post-collisional Miocene magmatism in the Kabylies (northern Algeria): Evidence for crustal stacking, delamination and slab detachment

    Science.gov (United States)

    Chazot, Gilles; Abbassene, Fatiha; Maury, René C.; Déverchère, Jacques; Bellon, Hervé; Ouabadi, Aziouz; Bosch, Delphine

    2017-01-01

    Miocene (17-11 Ma) magmatic activity in the Kabylies emplaced K-rich (and minor medium-K) calc-alkaline plutonic and volcanic rocks in five zones, delineating a ∼450 km long EW trending strip located along the northern coast of Algeria, between Annaba and Algiers. Their most likely source is the Kabylian subcontinental lithospheric mantle previously metasomatized during the Paleogene subduction of the Tethys oceanic lithosphere. Our preferred tectono-magmatic model involves a Tethyan slab detachment combined with African mantle delamination and crustal stacking, leading to the superimposition of the African continental crust over the Kabylian metasomatized lithospheric mantle. At ca. 17 Ma, the asthenospheric upwelling arising from lithospheric delamination and Tethyan slab tear triggered the thermal erosion of the latter mantle, inducing its partial melting. The corresponding mafic medium-K calc-alkaline magmas interacted with the African basement units during their ascent, generating intermediate to felsic K-rich calc-alkaline melts that display a characteristic trace element and isotopic crustal signature. Later on, slab tears propagated eastward and westward, promoting slab rollback perpendicular to plate convergence and inducing the emplacement of magmatic rocks of decreasing ages from central-eastern Algeria towards Tunisia and Morocco.

  7. Reliability of contractile properties of the knee extensor muscles in individuals with post-polio syndrome.

    Directory of Open Access Journals (Sweden)

    Eric L Voorn

    Full Text Available To assess the reliability of contractile properties of the knee extensor muscles in 23 individuals with post-polio syndrome (PPS and 18 age-matched healthy individuals.Contractile properties of the knee extensors were assessed from repeated electrically evoked contractions on 2 separate days, with the use of a fixed dynamometer. Reliability was determined for fatigue resistance, rate of torque development (MRTD, and early and late relaxation time (RT50 and RT25, using the intraclass correlation coefficient (ICC and standard error of measurement (SEM, expressed as % of the mean.In both groups, reliability for fatigue resistance was good, with high ICCs (>0.90 and small SEM values (PPS: 7.1%, healthy individuals: 7.0%. Reliability for contractile speed indices varied, with the best values found for RT50 (ICCs>0.82, SEM values <2.8%. We found no systematic differences between test and retest occasions, except for RT50 in healthy subjects (p = 0.016.In PPS and healthy individuals, the reliability of fatigue resistance, as obtained from electrically evoked contractions is high. The reliability of contractile speed is only moderate, except for RT50 in PPS, demonstrating high reliability.This was the first study to examine the reliability of electrically evoked contractile properties in individuals with PPS. Our results demonstrate its potential to study mechanisms underlying muscle fatigue in PPS and to evaluate changes in contractile properties over time in response to interventions or from natural course.

  8. A Reliability Model for Ni-BaTiO3-Based (BME) Ceramic Capacitors

    Science.gov (United States)

    Liu, Donhang

    2014-01-01

    The evaluation of multilayer ceramic capacitors (MLCCs) with base-metal electrodes (BMEs) for potential NASA space project applications requires an in-depth understanding of their reliability. The reliability of an MLCC is defined as the ability of the dielectric material to retain its insulating properties under stated environmental and operational conditions for a specified period of time t. In this presentation, a general mathematic expression of a reliability model for a BME MLCC is developed and discussed. The reliability model consists of three parts: (1) a statistical distribution that describes the individual variation of properties in a test group of samples (Weibull, log normal, normal, etc.), (2) an acceleration function that describes how a capacitors reliability responds to external stresses such as applied voltage and temperature (All units in the test group should follow the same acceleration function if they share the same failure mode, independent of individual units), and (3) the effect and contribution of the structural and constructional characteristics of a multilayer capacitor device, such as the number of dielectric layers N, dielectric thickness d, average grain size r, and capacitor chip size S. In general, a two-parameter Weibull statistical distribution model is used in the description of a BME capacitors reliability as a function of time. The acceleration function that relates a capacitors reliability to external stresses is dependent on the failure mode. Two failure modes have been identified in BME MLCCs: catastrophic and slow degradation. A catastrophic failure is characterized by a time-accelerating increase in leakage current that is mainly due to existing processing defects (voids, cracks, delamination, etc.), or the extrinsic defects. A slow degradation failure is characterized by a near-linear increase in leakage current against the stress time; this is caused by the electromigration of oxygen vacancies (intrinsic defects). The

  9. Isothermal solidification based packaging of biosensors at low temperatures

    International Nuclear Information System (INIS)

    Sharma, R.P.; Khanna, P.K.; Kumar, D.

    2010-01-01

    Thick film Au printed square contact pads are interconnected to Cu substrates at constant pressure and temperature using the isothermal solidification of Bi-In alloy on the joining surfaces. The effect of reaction time on the mechanical strength of the package has been analyzed. Thermal stability of the fabricated specimens have been measured and discussed. The delaminated surfaces examined optically reveal the morphology of the metallization zones on the joining substrates. The scanning electron microscopy of these surfaces is reported in this paper. Tests for thermal shock, pH resistivity and shelf life have been carried out to predict the reliability of the packaging for long term applications.

  10. Stand development and reliability tests of the thermal monitoring means for NPP

    International Nuclear Information System (INIS)

    Nalivaev, V.I.; Nikul'shin, V.S.; Kichigin, A.B.; Dirin, V.F.

    2003-01-01

    The paper is devoted to the reliability tests of thermoelectric thermometers and resistance thermometers during their operation in the nominal mode. Five stands Reliability are developed and operate for realization of tests of all manufactured thermal converters. delivered at NPP. Description of all stands are presented [ru

  11. Enhancement of Fracture Resistance by Multiple Cracks in Layered Structures under Mode I and Mix Mode Loading

    DEFF Research Database (Denmark)

    Goutianos, Stergios; Sørensen, Bent F.

    beams bonded together with a thermoset adhesive, more delamination cracks could be developed next to the main/primary adhesive/laminate crack. An analytical model, based on the J integral, was developed for multiple delaminations [3]. It is shown that the maximum possible increase (upper limit...

  12. Insulin resistance in obesity can be reliably identified from fasting plasma insulin.

    Science.gov (United States)

    ter Horst, K W; Gilijamse, P W; Koopman, K E; de Weijer, B A; Brands, M; Kootte, R S; Romijn, J A; Ackermans, M T; Nieuwdorp, M; Soeters, M R; Serlie, M J

    2015-12-01

    Insulin resistance is the major contributor to cardiometabolic complications of obesity. We aimed to (1) establish cutoff points for insulin resistance from euglycemic hyperinsulinemic clamps (EHCs), (2) identify insulin-resistant obese subjects and (3) predict insulin resistance from routinely measured variables. We assembled data from non-obese (n=112) and obese (n=100) men who underwent two-step EHCs using [6,6-(2)H2]glucose as tracer (insulin infusion dose 20 and 60 mU m(-2) min(-1), respectively). Reference ranges for hepatic and peripheral insulin sensitivity were calculated from healthy non-obese men. Based on these reference values, obese men with preserved insulin sensitivity or insulin resistance were identified. Cutoff points for insulin-mediated suppression of endogenous glucose production (EGP) and insulin-stimulated glucose disappearance rate (Rd) were 46.5% and 37.3 μmol kg(-)(1) min(-)(1), respectively. Most obese men (78%) had EGP suppression within the reference range, whereas only 12% of obese men had Rd within the reference range. Obese men with Rd obese men in age, body mass index (BMI), body composition, fasting glucose or cholesterol, but did have higher fasting insulin (110±49 vs 63±29 pmol l(-1), Pobese men could be identified with good sensitivity (80%) and specificity (75%) from fasting insulin >74 pmol l(-1). Most obese men have hepatic insulin sensitivity within the range of non-obese controls, but below-normal peripheral insulin sensitivity, that is, insulin resistance. Fasting insulin (>74 pmol l(-1) with current insulin immunoassay) may be used for identification of insulin-resistant (or metabolically unhealthy) obese men in research and clinical settings.

  13. Reliability assessment of aging structures subjected to gradual and shock deteriorations

    International Nuclear Information System (INIS)

    Wang, Cao; Zhang, Hao; Li, Quanwang

    2017-01-01

    Civil structures and infrastructure facilities are susceptible to deterioration posed by the effects of natural hazards and aggressive environmental conditions. These factors may increase the risk of service interruption of infrastructures, and should be taken into account when assessing the structural reliability during an infrastructure's service life. Modeling the resistance deterioration process reasonably is the basis for structural reliability analysis. In this paper, a novel model is developed for describing the deterioration of aging structures. The deterioration is a combination of two stochastic processes: the gradual deterioration posed by environmental effects and the shock deterioration caused by severe load attacks. The dependency of the deterioration magnitude on the load intensity is considered. The Gaussian copula function is employed to help construct the joint distribution of correlated random variables. Semi-analytical methods are developed to assess the structural failure time and the number of significant load events (shocks) to failure. Illustrative examples are presented to demonstrate the applicability of the proposed model in structural reliability analysis. Parametric studies are performed to investigate the role of deterioration-load correlation in structural reliability. - Highlights: • A new resistance deterioration model for aging structures is proposed. • Time-dependent reliability analysis methods incorporating the proposed deterioration model are developed. • Parametric studies are performed to investigate the role of deterioration-load correlation in structural reliability.

  14. Plastic packaged microcircuits: Quality, reliability, and cost issues

    Science.gov (United States)

    Pecht, Michael G.; Agarwal, Rakesh; Quearry, Dan

    1993-12-01

    Plastic encapsulated microcircuits (PEMs) find their main application in commercial and telecommunication electronics. The advantages of PEMs in cost, size, weight, performance, and market lead-time, have attracted 97% of the market share of worldwide microcircuit sales. However, PEMs have always been resisted in US Government and military applications due to the perception that PEM reliability is low. This paper surveys plastic packaging with respect to the issues of reliability, market lead-time, performance, cost, and weight as a means to guide part-selection and system-design.

  15. Resistive RAM: Simulation and Modeling for Reliable Design

    OpenAIRE

    García Redondo, Fernando

    2017-01-01

    Las tecnologías emergentes de resistencia variable o resistencia-commutativa, Resistive-Switching (RS) technologies, están consideradas como una de las alternativas más prometedoras para el futuro de aplicaciones electrónicas de almacenamiento y sistemas de computación. Características tales como su no-volatilidad, alta densidad de integración, bajo consumo, así como su compatibilidad con circuitos CMOS tradicionales, despierta el interés de fabricantes de dispositivos, diseñadores de circuit...

  16. Test-retest reliability for aerodynamic measures of voice.

    Science.gov (United States)

    Awan, Shaheen N; Novaleski, Carolyn K; Yingling, Julie R

    2013-11-01

    The purpose of this study was to investigate the intrasubject reliability of aerodynamic characteristics of the voice within typical/normal speakers across testing sessions using the Phonatory Aerodynamic System (PAS 6600; KayPENTAX, Montvale, NJ). Participants were 60 healthy young adults (30 males and 30 females) between the ages 18 and 31 years with perceptually typical voice. Participants were tested using the PAS 6600 (Phonatory Aerodynamic System) on two separate days with approximately 1 week between each session at approximately the same time of day. Four PAS protocols were conducted (vital capacity, maximum sustained phonation, comfortable sustained phonation, and voicing efficiency) and measures of expiratory volume, maximum phonation time, mean expiratory airflow (during vowel production) and target airflow (obtained via syllable repetition), peak air pressure, aerodynamic power, aerodynamic resistance, and aerodynamic efficiency were obtained during each testing session. Associated acoustic measures of vocal intensity and frequency were also collected. All phonations were elicited at comfortable pitch and loudness. All aerodynamic and associated variables evaluated in this study showed useable test-retest reliability (ie, intraclass correlation coefficients [ICCs] ≥ 0.60). A high degree of mean test-retest reliability was found across all subjects for aerodynamic and associated acoustic measurements of vital capacity, maximum sustained phonation, glottal resistance, and vocal intensity (all with ICCs > 0.75). Although strong ICCs were observed for measures of glottal power and mean expiratory airflow in males, weaker overall results for these measures (ICC range: 0.60-0.67) were observed in females subjects and sizable coefficients of variation were observed for measures of power, resistance, and efficiency in both men and women. Differences in degree of reliability from measure to measure were revealed in greater detail using methods such as ICCs and

  17. Transparent Electrodes with Nanotubes and Graphene for Printed Optoelectronic Applications

    Directory of Open Access Journals (Sweden)

    Marcin Słoma

    2014-01-01

    Full Text Available We report here on printed electroluminescent structures containing transparent electrodes made of carbon nanotubes and graphene nanoplatelets. Screen-printing and spray-coating techniques were employed. Electrodes and structures were examined towards optical parameters using spectrophotometer and irradiation meter. Electromechanical properties of transparent electrodes are exterminated with cyclical bending test. Accelerated aging process was conducted according to EN 62137 standard for reliability tests of electronics. We observed significant negative influence of mechanical bending on sheet resistivity of ITO, while resistivity of nanotube and graphene based electrodes remained stable. Aging process has also negative influence on ITO based structures resulting in delamination of printed layers, while those based on carbon nanomaterials remained intact. We observe negligible changes in irradiation for structures with carbon nanotube electrodes after accelerated aging process. Such materials demonstrate a high application potential in general purpose electroluminescent devices.

  18. Measurement of interfacial shear mechanical properties in thermal barrier coating systems by a barb pullout method

    International Nuclear Information System (INIS)

    Guo, S.Q.; Mumm, D.R.; Karlsson, A.M.; Kagawa, Y.

    2005-01-01

    A test technique has been developed to facilitate evaluation of the fracture characteristics of coatings and interfaces in thermal barrier coating (TBC) systems. The methodology has particular application in analyzing delamination crack growth, where crack propagation occurs under predominantly mode II loading. The technique has been demonstrated by quantitatively measuring the effective delamination fracture resistance of an electron-beam physical vapor deposition TBC

  19. ``The Princess and the Pea'' at the Nanoscale: Wrinkling and Delamination of Graphene on Nanoparticles

    Science.gov (United States)

    Yamamoto, Mahito; Pierre-Louis, Olivier; Huang, Jia; Fuhrer, Michael S.; Einstein, Theodore L.; Cullen, William G.

    2012-10-01

    Thin membranes exhibit complex responses to external forces or geometrical constraints. A familiar example is the wrinkling, exhibited by human skin, plant leaves, and fabrics, that results from the relative ease of bending versus stretching. Here, we study the wrinkling of graphene, the thinnest and stiffest known membrane, deposited on a silica substrate decorated with silica nanoparticles. At small nanoparticle density, monolayer graphene adheres to the substrate, detached only in small regions around the nanoparticles. With increasing nanoparticle density, we observe the formation of wrinkles which connect nanoparticles. Above a critical nanoparticle density, the wrinkles form a percolating network through the sample. As the graphene membrane is made thicker, global delamination from the substrate is observed. The observations can be well understood within a continuum-elastic model and have important implications for strain-engineering the electronic properties of graphene.

  20. Reliability assessment and probability based design of reinforced concrete containments and shear walls

    International Nuclear Information System (INIS)

    Hwang, H.; Reich, M.; Ellingwood, B.; Shinozuka, M.

    1986-03-01

    This report summarizes work completed under the program entitled, ''Probability-Based Load Combinations for Design of Category I Structures.'' Under this program, the probabilistic models for various static and dynamic loads were formulated. The randomness and uncertainties in material strengths and structural resistance were established. Several limit states of concrete containments and shear walls were identified and analytically formulated. Furthermore, the reliability analysis methods for estimating limit state probabilities were established. These reliability analysis methods can be used to evaluate the safety levels of nuclear structures under various combinations of static and dynamic loads. They can also be used to generate analytically the fragility data for PRA studies. In addition to the development of reliability analysis methods, probability-based design criteria for concrete containments and shear wall structures have also been developed. The proposed design criteria are in the load and resistance factor design (LRFD) format. The load and resistance factors are determined for several limit states and target limit state probabilities. Thus, the proposed design criteria are risk-consistent and have a well-established rationale. 73 refs., 18 figs., 16 tabs

  1. Error free physically unclonable function with programmed resistive random access memory using reliable resistance states by specific identification-generation method

    Science.gov (United States)

    Tseng, Po-Hao; Hsu, Kai-Chieh; Lin, Yu-Yu; Lee, Feng-Min; Lee, Ming-Hsiu; Lung, Hsiang-Lan; Hsieh, Kuang-Yeu; Chung Wang, Keh; Lu, Chih-Yuan

    2018-04-01

    A high performance physically unclonable function (PUF) implemented with WO3 resistive random access memory (ReRAM) is presented in this paper. This robust ReRAM-PUF can eliminated bit flipping problem at very high temperature (up to 250 °C) due to plentiful read margin by using initial resistance state and set resistance state. It is also promised 10 years retention at the temperature range of 210 °C. These two stable resistance states enable stable operation at automotive environments from -40 to 125 °C without need of temperature compensation circuit. The high uniqueness of PUF can be achieved by implementing a proposed identification (ID)-generation method. Optimized forming condition can move 50% of the cells to low resistance state and the remaining 50% remain at initial high resistance state. The inter- and intra-PUF evaluations with unlimited separation of hamming distance (HD) are successfully demonstrated even under the corner condition. The number of reproduction was measured to exceed 107 times with 0% bit error rate (BER) at read voltage from 0.4 to 0.7 V.

  2. AE analysis of delamination crack propagation in carbon fiber-reinforced polymer materials

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Sang Jae; Arakawa, Kazuo [Kyushu University, kasuga (Japan); Chen, Dingding [National University of Defense Technology, Changsha (China); Han, Seung Wook; Choi, Nak Sam [Hanyang University, Seoul (Korea, Republic of)

    2015-01-15

    Delamination fracture behavior was investigated using acoustic emission (AE) analysis on carbon fiber-reinforced polymer (CFRP) samples manufactured using vacuum-assisted resin transfer molding (VARTM). CFRP plate was fabricated using unidirectional carbon fiber fabric with a lay-up of six plies [+30/-30]6 , and a Teflon film was inserted as a starter crack. Test pieces were sectioned from the inlet and vent of the mold, and packed between two rectangular epoxy plates to load using a universal testing machine. The AE signals were monitored during tensile loading using two sensors. The average tensile load of the inlet specimens was slightly larger than that of the vent specimens; however, the data exhibited significant scattering due to non-uniform resin distribution, and there was no statistically significant different between the strength of the samples sectioned from the inlet or outlet of the mold. Each of the specimens exhibited similar AE characteristics, regardless of whether they were from the inlet or vent of the mold. Four kinds of damage mechanism were observed: micro-cracking, fiber-resin matrix debonding, fiber pull-out, and fiber failure; and three stages of the crack propagation process were identified.

  3. Numerical Flexural Strength Analysis of Thermally Stressed Delaminated Composite Structure under Sinusoidal Loading

    Science.gov (United States)

    Hirwani, C. K.; Biswash, S.; Mehar, K.; Panda, S. K.

    2018-03-01

    In this article, we investigate the thermomechanical deflection characteristics of the debonded composite plate structure using an isoparametric type of higher-order finite element model. The current formulation is derived using higher-order kinematic theory and the displacement variables described as constant along the thickness direction whereas varying nonlinearly for the in-plane directions. The present mid-plane kinematic model mainly obsoletes the use of shear correction factor as in the other lower-order theories. The separation between the adjacent layers is modeled via the sub-laminate technique and the intermittent continuity conditions imposed to avoid the mathematical ill conditions. The governing equation of equilibrium of the damaged plate structure under the combined state of loading are obtained using the variational principle and solved numerically to compute the deflection values. Further, the convergence test has been performed by refining the numbers of elements and validated through comparing the present results with available published values. The usefulness of the proposed formulation has been discussed by solving the different kind of numerical examples including the size, location and position of delamination.

  4. Tuning resistance states by thickness control in an electroforming-free nanometallic complementary resistance random access memory

    Science.gov (United States)

    Yang, Xiang; Lu, Yang; Lee, Jongho; Chen, I.-Wei

    2016-01-01

    Tuning low resistance state is crucial for resistance random access memory (RRAM) that aims to achieve optimal read margin and design flexibility. By back-to-back stacking two nanometallic bipolar RRAMs with different thickness into a complementary structure, we have found that its low resistance can be reliably tuned over several orders of magnitude. Such high tunability originates from the exponential thickness dependence of the high resistance state of nanometallic RRAM, in which electron wave localization in a random network gives rise to the unique scaling behavior. The complementary nanometallic RRAM provides electroforming-free, multi-resistance-state, sub-100 ns switching capability with advantageous characteristics for memory arrays.

  5. Tuning resistance states by thickness control in an electroforming-free nanometallic complementary resistance random access memory

    International Nuclear Information System (INIS)

    Yang, Xiang; Lu, Yang; Lee, Jongho; Chen, I-Wei

    2016-01-01

    Tuning low resistance state is crucial for resistance random access memory (RRAM) that aims to achieve optimal read margin and design flexibility. By back-to-back stacking two nanometallic bipolar RRAMs with different thickness into a complementary structure, we have found that its low resistance can be reliably tuned over several orders of magnitude. Such high tunability originates from the exponential thickness dependence of the high resistance state of nanometallic RRAM, in which electron wave localization in a random network gives rise to the unique scaling behavior. The complementary nanometallic RRAM provides electroforming-free, multi-resistance-state, sub-100 ns switching capability with advantageous characteristics for memory arrays

  6. Alps, Carpathians and Dinarides-Hellenides: about plates, micro-plates and delaminated crustal blocks

    Science.gov (United States)

    Schmid, Stefan

    2014-05-01

    Before the onset of Europe-Africa continental collision in the Dinarides-Hellenides (around 60Ma) and in the Alps and Western Carpathians (around 35 Ma), and at a large scale, the dynamics of orogenic processes in the Mediterranean Alpine chains were governed by Europe-Africa plate convergence leading to the disappearance of large parts of intervening oceanic lithosphere, i.e. the northern branch of Neotethys along the Sava-Izmir-Ankara suture and Alpine Tethys along the Valais-Magura suture (Schmid et al. 2008). In spite of this, two major problems concerning the pre-collisional stage are still poorly understood: (1) by now we only start to understand geometry, kinematics and dynamics of the along-strike changes in the polarity of subduction between Alps-Carpathians and Dinarides-Hellenides, and (2) it is not clear yet during exactly which episodes and to what extent intervening rifted continental fragments such as, for example, Iberia-Briançonnais, Tisza, Dacia, Adria-Taurides moved independently as micro-plates, and during which episodes they remained firmly attached to Europa or Africa from which they broke away. As Europe-Africa plate convergence slowed down well below 1 cm/yr at around 30 Ma ago these pre-collisional processes driven by plate convergence on a global scale gave way to more local processes of combined roll-back and crustal delamination in the Pannonian basin of the Carpathian embayment and in the Aegean (as well as in the Western Mediterranean, not discussed in this contribution). In the case of the Carpathian embayment E-directed roll back totally unrelated to Europe-Africa N-S-directed convergence, started at around 20 Ma ago, due to the presence relict oceanic lithosphere in the future Pannonian basin that remained un-subducted during collision. Due to total delamination of the crust from the eastward rolling back European mantle lithosphere the anticlockwise rotating ALCAPA crustal block, consisting of Eastern Alps and Western Carpathian

  7. Reliability Analysis of a Steel Frame

    Directory of Open Access Journals (Sweden)

    M. Sýkora

    2002-01-01

    Full Text Available A steel frame with haunches is designed according to Eurocodes. The frame is exposed to self-weight, snow, and wind actions. Lateral-torsional buckling appears to represent the most critical criterion, which is considered as a basis for the limit state function. In the reliability analysis, the probabilistic models proposed by the Joint Committee for Structural Safety (JCSS are used for basic variables. The uncertainty model coefficients take into account the inaccuracy of the resistance model for the haunched girder and the inaccuracy of the action effect model. The time invariant reliability analysis is based on Turkstra's rule for combinations of snow and wind actions. The time variant analysis describes snow and wind actions by jump processes with intermittencies. Assuming a 50-year lifetime, the obtained values of the reliability index b vary within the range from 3.95 up to 5.56. The cross-profile IPE 330 designed according to Eurocodes seems to be adequate. It appears that the time invariant reliability analysis based on Turkstra's rule provides considerably lower values of b than those obtained by the time variant analysis.

  8. Durability and Reliability of Large Diameter HDPE Pipe for Water Main Applications (Web Report 4485)

    Science.gov (United States)

    Research validates HDPE as a suitable material for use in municipal piping systems, and more research may help users maximize their understanding of its durability and reliability. Overall, corrosion resistance, hydraulic efficiency, flexibility, abrasion resistance, toughness, f...

  9. Applications of a damage tolerance analysis methodology in aircraft design and production

    Science.gov (United States)

    Woodward, M. R.; Owens, S. D.; Law, G. E.; Mignery, L. A.

    1992-01-01

    Objectives of customer mandated aircraft structural integrity initiatives in design are to guide material selection, to incorporate fracture resistant concepts in the design, to utilize damage tolerance based allowables and planned inspection procedures necessary to enhance the safety and reliability of manned flight vehicles. However, validated fracture analysis tools for composite structures are needed to accomplish these objectives in a timely and economical manner. This paper briefly describes the development, validation, and application of a damage tolerance methodology for composite airframe structures. A closed-form analysis code, entitled SUBLAM was developed to predict the critical biaxial strain state necessary to cause sublaminate buckling-induced delamination extension in an impact damaged composite laminate. An embedded elliptical delamination separating a thin sublaminate from a thick parent laminate is modelled. Predicted failure strains were correlated against a variety of experimental data that included results from compression after impact coupon and element tests. An integrated analysis package was developed to predict damage tolerance based margin-of-safety (MS) using NASTRAN generated loads and element information. Damage tolerance aspects of new concepts are quickly and cost-effectively determined without the need for excessive testing.

  10. Challenges to Resistance Welding

    DEFF Research Database (Denmark)

    Song, Quanfeng

    This report originates from the compulsory defense during my Ph.D. study at the Technical University of Denmark. Resistance welding is an old and well-proven technology. Yet the emergence of more and more new materials, new designs, invention off new joining techniques, and more stringent...... requirement in quality have imposed challenges to the resistance welding. More some research and development have to be done to adapt the old technology to the manufacturing industry of the 21st century. In the 1st part of the report, the challenging factors to the resistance welding are reviewed. Numerical...... simulation of resistance welding has been under development for many years. Yet it is no easy to make simulation results reliable and accurate because of the complexity of resistance welding process. In the 2nd part of the report numerical modeling of resistance welding is reviewed, some critical factors...

  11. Seismic reliability assessment methodology for CANDU concrete containment structures

    International Nuclear Information System (INIS)

    Stephens, M.J.; Nessim, M.A.; Hong, H.P.

    1995-05-01

    A study was undertaken to develop a reliability-based methodology for the assessment of existing CANDU concrete containment structures with respect to seismic loading. The focus of the study was on defining appropriate specified values and partial safety factors for earthquake loading and resistance parameters. Key issues addressed in the work were the identification of an approach to select design earthquake spectra that satisfy consistent safety levels, and the use of structure-specific data in the evaluation of structural resistance. (author). 23 refs., 9 tabs., 15 figs

  12. “The Princess and the Pea” at the Nanoscale: Wrinkling and Delamination of Graphene on Nanoparticles

    Directory of Open Access Journals (Sweden)

    Mahito Yamamoto

    2012-12-01

    Full Text Available Thin membranes exhibit complex responses to external forces or geometrical constraints. A familiar example is the wrinkling, exhibited by human skin, plant leaves, and fabrics, that results from the relative ease of bending versus stretching. Here, we study the wrinkling of graphene, the thinnest and stiffest known membrane, deposited on a silica substrate decorated with silica nanoparticles. At small nanoparticle density, monolayer graphene adheres to the substrate, detached only in small regions around the nanoparticles. With increasing nanoparticle density, we observe the formation of wrinkles which connect nanoparticles. Above a critical nanoparticle density, the wrinkles form a percolating network through the sample. As the graphene membrane is made thicker, global delamination from the substrate is observed. The observations can be well understood within a continuum-elastic model and have important implications for strain-engineering the electronic properties of graphene.

  13. Ultrasonic signal analysis according to laser ultrasound generation position for the detection of delamination in composites

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Kyung Min; Choi In Young; Kim, Seong Jong; Kang, Young June [Chonbuk National University, Jeonju (Korea, Republic of); Lee, Gil Dong [GP Inc., Daejeon (Korea, Republic of)

    2015-11-15

    Carbon-fiber-reinforced plastic should be inspected in the fabrication process to enhance quality by preventing defects, such as delamination and voids. Conventional ultrasonic evaluation methods cannot be applied during the fabrication process because they require contact measurement by a transducer. Thus, an optical method using a laser was employed in this study for non-contact ultrasonic evaluation. Ultrasonic signals were generated by a pulsed laser and received by using a laser interferometer. First, an ultrasonic signal was generated from the back side of a material sample with artificial internal defects in the composite. The ultrasonic signal directed through the interior of the specimen was then detected at the front side. After determining the locations of the internal defects, the defects were quantitatively evaluated from the front side of the composite by using ultrasonic signal generation and reception.

  14. [Reactance proneness, collectivism, uniqueness, and resistance to persuasion].

    Science.gov (United States)

    Imajo, Shuzo

    2002-10-01

    This study examined the reliability and validity of Japanese psychological reactance scales. A total of 167 undergraduates completed a questionnaire of Therapeutic Reactance Scale (TRS), the Hong Reactance Scale (HRS), the Uniqueness Scale, and the Collectivism Scale. They also received messages involving three persuasion situations that were either high or low in terms of threat, and were asked to describe their reactions to them. The author categorized the reactions into three: acceptance, indirect resistance, and direct resistance. Reliabilities of the reactance scales were satisfactory. Their scores positively correlated with uniqueness scores, and negatively with collectivism scores. Those high on reactance proneness were less persuaded in two of the three situations. But in the third, an HRS by threat interaction was observed, indicating that only those who were high on reactance proneness under the high-threat condition showed resistance to persuasion. These results suggest that the Japanese versions of reactance scale were reliable and valid. However, the assertiveness aspect of TRS may not be appropriate for the definition of reactance. The influence of culture on psychological reactance was also discussed.

  15. Patterns of Force, Sequences of Resistance

    DEFF Research Database (Denmark)

    Lindegaard, Marie Rosenkrantz; Daniël De Vries, Thomas; Bernasco, Wim

    2018-01-01

    Robberies are improvised encounters involving offender threat, sometimes force, and often victim resistance. While the association between threat, force, and resistance in robberies is well-established, sequential patterns are disputed due to biases of retrospective studies. To overcome these bia...... the likelihood of victim resistance despite having no effect on offender vio- lence. By providing more reliable and detailed accounts of real-life behavior during robberies, our analysis illustrates the potential of a newly emergent field of studies of crimes caught on camera....

  16. Reliability-based evaluation of bridge components for consistent safety margins.

    Science.gov (United States)

    2010-10-01

    The Load and Resistant Factor Design (LRFD) approach is based on the concept of structural reliability. The approach is more : rational than the former design approaches such as Load Factor Design or Allowable Stress Design. The LRFD Specification fo...

  17. Testing and Modeling of Contact Problems in Resistance Welding

    DEFF Research Database (Denmark)

    Song, Quanfeng

    together two or three cylindrical parts as well as disc-ring pairs of dissimilar metals. The tests have demonstrated the effectiveness of the model. A theoretical and experimental study is performed on the contact resistance aiming at a more reliable model for numerical simulation of resistance welding......As a part of the efforts towards a professional and reliable numerical tool for resistance welding engineers, this Ph.D. project is dedicated to refining the numerical models related to the interface behavior. An FE algorithm for the contact problems in resistance welding has been developed...... for the formulation, and the interfaces are treated in a symmetric pattern. The frictional sliding contact is also solved employing the constant friction model. The algorithm is incorporated into the finite element code. Verification is carried out in some numerical tests as well as experiments such as upsetting...

  18. Improved design of large wind turbine blades of fibre composites (Phase 2) - Summary Report

    DEFF Research Database (Denmark)

    Sørensen, Bent F.; Branner, K.; Stang, H.

    2005-01-01

    girder section subjected to transverse forces was investigated experimentally and by modelling. Buckling-driven delamination of planar specimens was studied on experimentally and by modelling. A novel approachwas proposed for the determination of mixed mode cohesive laws for large-scale crack bridging...... problems. The normal and shear stresses of the cohesive laws were obtained from data of the fracture resistance and the normal and tangential displacements ofthe cohesive zone. Delamination of a thin layer bonded to an elastic substrate close to corners and edges was also analysed. Results for the shape...... of the interface crack front and critical stress for steady-state delamination were obtained....

  19. Heat resistant/radiation resistant cable and incore structure test device for FBR type reactor

    International Nuclear Information System (INIS)

    Tanimoto, Hajime; Shiono, Takeo; Sato, Yoshimi; Ito, Kazumi; Sudo, Shigeaki; Saito, Shin-ichi; Mitsui, Hisayasu.

    1995-01-01

    A heat resistant/radiation resistant coaxial cable of the present invention comprises an insulation layer, an outer conductor and a protection cover in this order on an inner conductor, in which the insulation layer comprises thermoplastic polyimide. In the same manner, a heat resistant/radiation resistant power cable has an insulation layer comprising thermoplastic polyimide on a conductor, and is provided with a protection cover comprising braid of alamide fibers at the outer circumference of the insulation layer. An incore structure test device for an FBR type reactor comprises the heat resistant/radiation resistant coaxial cable and/or the power cable. The thermoplastic polyimide can be extrusion molded, and has excellent radiation resistant by the extrusion, as well as has high dielectric withstand voltage, good flexibility and electric characteristics at high temperature. The incore structure test device for the FBR type reactor of the present invention comprising such a cable has excellent reliability and durability. (T.M.)

  20. Quantitative 3D X-ray imaging of densification, delamination and fracture in a micro-composite under compression

    DEFF Research Database (Denmark)

    Bø Fløystad, Jostein; Skjønsfjell, Eirik Torbjørn Bakken; Guizar-Sicairos, Manuel

    2015-01-01

    Phase-contrast three-dimensional tomograms showing in unprecedented detail the mechanical response of a micro-composite subjected to a mechanical compression test are reported. The X-ray ptychography images reveal the deformation and fracture processes of a 10 μm diameter composite, consisting...... X-ray microscopy as a powerful tool for in situ studies of the mechanical properties of nanostructured devices, structures, and composites. Ptychographic X-ray microscopy can be used for quantitatively studying the mechanical properties of microscale composites. Phase-contrast three...... of a spherical polymer bead coated with a nominally 210 nm metal shell. The beginning delamination of the shell from the core can be directly observed at an engineering strain of a few percent. Pre-existing defects are shown to dictate the deformation behavior of both core and shell. The strain state...

  1. Infrared spectroscopy, nano-mechanical properties, and scratch resistance of esthetic orthodontic coated archwires.

    Science.gov (United States)

    da Silva, Dayanne Lopes; Santos, Emanuel; Camargo, Sérgio de Souza; Ruellas, Antônio Carlos de Oliveira

    2015-09-01

    To evaluate the material composition, mechanical properties (hardness and elastic modulus), and scratch resistance of the coating of four commercialized esthetic orthodontic archwires. The coating composition of esthetic archwires was assessed by Fourier-transform infrared spectroscopy (FTIR). Coating hardness and elastic modulus were analyzed with instrumented nano-indentation tests. Scratch resistance of coatings was evaluated by scratch test. Coating micromorphologic characteristics after scratch tests were observed in a scanning electron microscope. Statistical differences were investigated using analysis of variance and Tukey post hoc test. The FTIR results indicate that all analyzed coatings were markedly characterized by the benzene peak at about 1500 cm(-1). The coating hardness and elastic modulus average values ranged from 0.17 to 0.23 GPa and from 5.0 to 7.6 GPa, respectively. Scratch test showed a high coating elasticity after load removal with elastic recoveries >60%, but different failure features could be observed along the scratches. The coatings of esthetic archwires evaluated are probably a composite of polyester and polytetrafluoroethylene. Delamination, crack propagation, and debris generation could be observed along the coating scratches and could influence its durability in the oral environment.

  2. Termovision and electricity capacitance measurements as a evaluation of a helicopter rotor’s blades delamination

    Directory of Open Access Journals (Sweden)

    Gębura Andrzej

    2015-12-01

    Full Text Available The article presents essential elements reached during investigations of heat section of rotor blades which have been done in AFIT. The investigations were related to a valuation of helicopter’s rotor blades delamination. They used a method of thermal field measurement as well as a electricity capacitance between an airframe and a heat element of the installation. A suggestion of such measurements appeared during the disassembly of rotor blade heat sections when some local unglue of heat element’s tape from the structure of blade’s heating pack has seen. Spots nearby separation of adhesive are a potential area of a local temperature increase, both the electric heating element and the mechanical structure of the blade. This is especially dangerous for composite structures. Overheated composite structures characterized by reduced flexibility and becomes prone to cracking. Therefore, the possibility of non-invasive monitoring adhesive spots, without removing the blades would be particularly useful.

  3. Low-level quinolone-resistance in multi-drug resistant typhoid

    Energy Technology Data Exchange (ETDEWEB)

    Mirza, S H; Khan, M A [Armed Forces Inst. of Pathology, Rawalpindi (Pakistan). Dept. of Microbiolgy

    2008-01-15

    To find out the frequency of low-level quinolone-resistance in Multi-Drug Resistant (MDR) typhoid using nalidixic acid screening disc. Blood was obtained from suspected cases of typhoid fever and cultured in to BacT/ALERT. The positive blood cultures bottles were subcultured. The isolates were identified by colony morphology and biochemical tests using API-20E galleries. Susceptibility testing of isolates was done by modified Kirby-Bauer disc diffusion method on Muellar Hinton Agar. For the isolates, which were resistant to nalidixic acid by disc diffusion method, Minimal Inhibitory Concentrations (MICs) of ciprofloxacin and nalidixic acid were determined by using the E-test strips. Disc diffusion susceptibility tests and MICs were interpreted according to the guidelines provided by National Committee for Control Laboratory Standard (NCCLS). A total of 21(65.5%) out of 32 isolates of Salmonellae were nalidixic acid-resistant by disk diffusion method. All the nalidixic acid-resistant isolates by disc diffusion method were confirmed by MICs for both ciprofloxacin and nalidixic acid. All the nalidixic acid-resistant isolates had a ciprofloxacin MIC of 0.25-1 microg/ml (reduced susceptibility) and nalidixic acid MICs > 32 microg (resistant). Out of all Salmonella isolates, 24 (75%) were found to be MDR, and all were S. typbi. Low-level quinolone-resistance in typhoid was high in this small series. Screening for nalidixic acid resistance with a 30 microg nalidixic acid disk is a reliable and cost-effective method to detect low-level fluoroquinolone resistance, especially in the developing countries. (author)

  4. Low-level quinolone-resistance in multi-drug resistant typhoid

    International Nuclear Information System (INIS)

    Mirza, S.H.; Khan, M.A.

    2008-01-01

    To find out the frequency of low-level quinolone-resistance in Multi-Drug Resistant (MDR) typhoid using nalidixic acid screening disc. Blood was obtained from suspected cases of typhoid fever and cultured in to BacT/ALERT. The positive blood cultures bottles were subcultured. The isolates were identified by colony morphology and biochemical tests using API-20E galleries. Susceptibility testing of isolates was done by modified Kirby-Bauer disc diffusion method on Muellar Hinton Agar. For the isolates, which were resistant to nalidixic acid by disc diffusion method, Minimal Inhibitory Concentrations (MICs) of ciprofloxacin and nalidixic acid were determined by using the E-test strips. Disc diffusion susceptibility tests and MICs were interpreted according to the guidelines provided by National Committee for Control Laboratory Standard (NCCLS). A total of 21(65.5%) out of 32 isolates of Salmonellae were nalidixic acid-resistant by disk diffusion method. All the nalidixic acid-resistant isolates by disc diffusion method were confirmed by MICs for both ciprofloxacin and nalidixic acid. All the nalidixic acid-resistant isolates had a ciprofloxacin MIC of 0.25-1 microg/ml (reduced susceptibility) and nalidixic acid MICs > 32 microg (resistant). Out of all Salmonella isolates, 24 (75%) were found to be MDR, and all were S. typbi. Low-level quinolone-resistance in typhoid was high in this small series. Screening for nalidixic acid resistance with a 30 microg nalidixic acid disk is a reliable and cost-effective method to detect low-level fluoroquinolone resistance, especially in the developing countries. (author)

  5. Late Miocene extensional systems in northern Tunisia and their relation with SE directed delamination of the African subcontinental mantle lithosphere

    Science.gov (United States)

    Booth-Rea, Guillermo; Gaidi, Seif; Melki, Fetheddine; Pérez-Peña, Vicente; Marzougui, Wissem; Azañón, Jose Miguel; Galve, Jorge Pedro

    2017-04-01

    Recent work has proposed the delamination of the subcontinental mantle lithosphere under northern Tunisia during the late Miocene. This process is required to explain the present location of the Tunisian segment of the African slab, imaged by seismic tomography, hanging under the Gulf of Gabes to the south of Tunisia. Thus, having retreated towards the SE several hundred km from its original position under the Tellian-Atlas nappe contact that crops out along the north of Tunisia. However, no tectonic structures have been described which could be related to this mechanism of lithospheric mantle peeling. Here we describe for the first time extensional fault systems in northern Tunisia that strongly thinned the Tellian nappes, exhuming rocks from the Tunisian Atlas in the core of folded extensional detachments. Two normal fault systems with sub-orthogonal extensional transport occur. These were active during the late Miocene associated to the extrusion of 13 Ma granodiorite and 9 Ma rhyodacite in the footwall of the Nefza detachment. We have differentiated an extensional system formed by low-angle normal faults with NE- and SW-directed transport cutting through the Early to Middle Miocene Tellian nappen stack and a later system of low and high-angle normal faults that cuts down into the underlying Tunisian Atlas units with SE-directed transport, which root in the Nefza detachment. Both normal fault systems have been later folded and cut by thrusts during Plio-Quaternary NW-SE directed compression. These findings change the interpretation of the tectonic evolution of Tunisia that has always been framed in a transpressive to compressive setting, manifesting the extensional effects of Late Miocene lithospheric mantle delamination under northern Tunisia.

  6. Reliability-based design and planning of inspection and monitoring of offshore wind turbines

    DEFF Research Database (Denmark)

    Dominguez, Sergio Marquez

    When the wind is blowing fiercely, wind turbines must resist. Wind turbines have to withstand the rough environmental conditions in the most reliable manner and start to produce renewable energy when the wind becomes friendly again. Never give up ‘wind turbine’ face the winds and be proud of cont...... of probability and statistics for application in structural reliability-based risk inspections....

  7. Reliability-based design code calibration for concrete containment structures

    International Nuclear Information System (INIS)

    Han, B.K.; Cho, H.N.; Chang, S.P.

    1991-01-01

    In this study, a load combination criteria for design and a probability-based reliability analysis were proposed on the basis of a FEM-based random vibration analysis. The limit state model defined for the study is a serviceability limit state of the crack failure that causes the emission of radioactive materials, and the results are compared with the case of strength limit state. More accurate reliability analyses under various dynamic loads such as earthquake loads were made possible by incorporating the FEM and random vibration theory, which is different from the conventional reliability analysis method. The uncertainties in loads and resistance available in Korea and the references were adapted to the situation of Korea, and especially in case of earthquake, the design earthquake was assessed based on the available data for the probabilistic description of earthquake ground acceleration in the Korea peninsula. The SAP V-2 is used for a three-dimensional finite element analysis of concrete containment structure, and the reliability analysis is carried out by modifying HRAS reliability analysis program for this study. (orig./GL)

  8. The Stigma Resistance Scale: A multi-sample validation of a new instrument to assess mental illness stigma resistance.

    Science.gov (United States)

    Firmin, Ruth L; Lysaker, Paul H; McGrew, John H; Minor, Kyle S; Luther, Lauren; Salyers, Michelle P

    2017-12-01

    Although associated with key recovery outcomes, stigma resistance remains under-studied largely due to limitations of existing measures. This study developed and validated a new measure of stigma resistance. Preliminary items, derived from qualitative interviews of people with lived experience, were pilot tested online with people self-reporting a mental illness diagnosis (n = 489). Best performing items were selected, and the refined measure was administered to an independent sample of people with mental illness at two state mental health consumer recovery conferences (n = 202). Confirmatory factor analyses (CFA) guided by theory were used to test item fit, correlations between the refined stigma resistance measure and theoretically relevant measures were examined for validity, and test-retest correlations of a subsample were examined for stability. CFA demonstrated strong fit for a 5-factor model. The final 20-item measure demonstrated good internal consistency for each of the 5 subscales, adequate test-retest reliability at 3 weeks, and strong construct validity (i.e., positive associations with quality of life, recovery, and self-efficacy, and negative associations with overall symptoms, defeatist beliefs, and self-stigma). The new measure offers a more reliable and nuanced assessment of stigma resistance. It may afford greater personalization of interventions targeting stigma resistance. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. The Reliability of Individualized Load-Velocity Profiles.

    Science.gov (United States)

    Banyard, Harry G; Nosaka, K; Vernon, Alex D; Haff, G Gregory

    2017-11-15

    This study examined the reliability of peak velocity (PV), mean propulsive velocity (MPV), and mean velocity (MV) in the development of load-velocity profiles (LVP) in the full depth free-weight back squat performed with maximal concentric effort. Eighteen resistance-trained men performed a baseline one-repetition maximum (1RM) back squat trial and three subsequent 1RM trials used for reliability analyses, with 48-hours interval between trials. 1RM trials comprised lifts from six relative loads including 20, 40, 60, 80, 90, and 100% 1RM. Individualized LVPs for PV, MPV, or MV were derived from loads that were highly reliable based on the following criteria: intra-class correlation coefficient (ICC) >0.70, coefficient of variation (CV) ≤10%, and Cohen's d effect size (ES) 0.05) between trials, movement velocities, or between linear regression versus second order polynomial fits. PV 20-100% , MPV 20-90% , and MV 20-90% are reliable and can be utilized to develop LVPs using linear regression. Conceptually, LVPs can be used to monitor changes in movement velocity and employed as a method for adjusting sessional training loads according to daily readiness.

  10. Layered rare-earth hydroxide (LRH, R = Tb, Y) composites with fluorescein: delamination, tunable luminescence and application in chemosensoring for detecting Fe(iii) ions.

    Science.gov (United States)

    Su, Feifei; Guo, Rong; Yu, Zihuan; Li, Jian; Liang, Zupei; Shi, Keren; Ma, Shulan; Sun, Genban; Li, Huifeng

    2018-04-17

    We demonstrate a novel example of tunable luminescence and the application of the delaminated FLN/OS-LRH composites (LRHs are layered rare-earth hydroxides, R = Tb, Y; FLN is the fluorescein named 2-(6-hydroxy-3-oxo-(3H)-xanthen-9-yl)benzoic acid; OS is the anionic surfactant 1-octane sulfonic acid sodium) in detecting Fe(iii) ions. The FLNxOS1-x species (x = 0.02, 0.05, 0.10, and 0.20) are intercalated into the LTbyY1-yH layers (y = 1, 0.9, 0.7, 0.5, 0.3, 0.1 and 0) by ion exchange reactions to yield the composites FLNxOS1-x-LTbyY1-yH. In the solid state, the LYH composites display green emission (564 nm) arising from the organic FLN, while in LTbH composites, the luminescence of the Tb3+ in the layers (545 nm) and the FLN in the interlayers is co-quenched. In the delaminated state in formamide (FM), FLNxOS1-x-LTbH composites display green to yellowish-green luminescence (540-574 nm) following the increasing FLN/OS ratio; while the FLN0.02OS0.98-LTbyY1-yH composites show green emission at ∼540 nm. The fluorescence lifetimes of the composites (4.22-4.63 ns) are comparable to the free FLN-Na, and the quantum yields (31.62-78.70%) of the composites especially that (78.70%) of the FLN0.02OS0.98-LYH are much higher than that (28.40%) of free FLN-Na. The recognition ability of the FLN0.02OS0.98-LYH composite for metal cations is researched. The delaminated FLN0.02OS0.98-LYH colloidal suspension exhibits high selectivity for Fe3+ over other ions (Mg2+, Al3+, Ni2+, Co2+, Cu2+, Zn2+, Mn2+, Pb2+, and Cd2+) with fluorescence quenching, which can work as a kind of turn-off fluorescence sensor for the detection of Fe3+. The detection limit of Fe3+ is determined to be 2.58 × 10-8 M and the quenching constant (Ksv) is 1.70 × 103 M-1. This is the first work on LRH materials working as a chemosensor for recognising metal cations. It provides a new approach for the design of LRH materials to be applied in fluorescence chemosensing.

  11. Microfractographic analysis of delamination growth in fatigue loaded - carbon fibre/thermosetting matrix composites; Mikrofraktographische Analyse des Delaminationswachstums in zyklisch belasteten Kohlenstoffaser/Duroplastharz-Verbundwerkstoffen

    Energy Technology Data Exchange (ETDEWEB)

    Heutling, F.; Franz, H.E. [Daimler-Benz AG, Muenchen (Germany); Friedrich, K. [Kaiserslautern Univ. (Germany). Inst. for Composite Materials Ltd.

    1998-05-01

    Carbon-fibre-reinforced plastics (CFRP) are known to be considerably less sensitive to fatigue loading than aluminium (Al) alloys, for instance. However, even in the presence of small delaminations, the damage tolerance of structural components may be considerably reduced. The scope of the present contribution is to investigate fatigue phenomena in CFRP materials (with thermosetting matrix) by means of microfractography. The microfractographic features of the fracture surfaces mirror the processes of deformation and fracture at the delamination front. The fatigue fracture behaviour of a CFRP laminate subjected to cyclic mixed-mode loading is determined by matrix-controlled failure mechanisms. Under pure mode-II loading conditions, rollers in addition to fatigue striations appear in the fibre imprints whose formation mechanism was explained by means of high-resolution field-emission scanning electron microscopy (FE-SEM). The ratio between the local tensile and shear stress components influences the propagation direction of secondary cracks originating at the fibres. The local fracture propagations in these secondary cracks can be recognised through the fatigue striations appearing on the surface of the matrix. A comparison with static mixed-mode loading reveals that in both cases the crack propagation follows the path of the local maximum main stress. Applying mathematical relationships derived from the theory of elasticity permitted developing a mixed-mode loading model which makes it possible to predict the crack processes and hence to explain the formation of typical fracture-morphological features. (orig.) 26 refs.

  12. Resistance controllability and variability improvement in a TaO{sub x}-based resistive memory for multilevel storage application

    Energy Technology Data Exchange (ETDEWEB)

    Prakash, A., E-mail: amitknp@postech.ac.kr, E-mail: amit.knp02@gmail.com, E-mail: hwanghs@postech.ac.kr; Song, J.; Hwang, H., E-mail: amitknp@postech.ac.kr, E-mail: amit.knp02@gmail.com, E-mail: hwanghs@postech.ac.kr [Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-ro, Nam-gu, Pohang, 790-784 (Korea, Republic of); Deleruyelle, D.; Bocquet, M. [Im2np, UMR CNRS 7334, Aix-Marseille Université, Marseille (France)

    2015-06-08

    In order to obtain reliable multilevel cell (MLC) characteristics, resistance controllability between the different resistance levels is required especially in resistive random access memory (RRAM), which is prone to resistance variability mainly due to its intrinsic random nature of defect generation and filament formation. In this study, we have thoroughly investigated the multilevel resistance variability in a TaO{sub x}-based nanoscale (<30 nm) RRAM operated in MLC mode. It is found that the resistance variability not only depends on the conductive filament size but also is a strong function of oxygen vacancy concentration in it. Based on the gained insights through experimental observations and simulation, it is suggested that forming thinner but denser conductive filament may greatly improve the temporal resistance variability even at low operation current despite the inherent stochastic nature of resistance switching process.

  13. Reliability Testing of Cable on Environmental Humidity Condition

    International Nuclear Information System (INIS)

    Situmorang, Johnny; Puradwi, I.W; Sony T, D.T; Handoyo, Demon; Mulyanto, Dwijo; Kusmono, Slamet

    2000-01-01

    Reliability testing of cable on humidified condition has been carried out. As a result, the failure occurred due to reduction of current by increasing the resistance on rising temperature testing. For humidified condition the result which are observed did not significant at the stated condition of testing. The needed time up to the failure criteria increased as a temperature testing increased

  14. Waist-to-height ratio is as reliable as biochemical markers to discriminate pediatric insulin resistance.

    Science.gov (United States)

    Alvim, Rafael de Oliveira; Zaniqueli, Divanei; Neves, Felipe Silva; Pani, Virgilia Oliveira; Martins, Caroline Resende; Peçanha, Marcos Alves de Souza; Barbosa, Míriam Carmo Rodrigues; Faria, Eliane Rodrigues de; Mill, José Geraldo

    2018-05-07

    Given the importance of incorporating simple and low-cost tools into the pediatric clinical setting to provide screening for insulin resistance, the present study sought to investigate whether waist-to-height ratio is comparable to biochemical markers for the discrimination of insulin resistance in children and adolescents. This cross-sectional study involved students from nine public schools. In total, 296 children and adolescents of both sexes, aged 8-14 years, composed the sample. Waist-to-height ratio, triglycerides/glucose index, and triglycerides-to-HDL-C ratio were determined according to standard protocols. Insulin resistance was defined as homeostatic model assessment for insulin resistance with cut-off point ≥3.16. Age, body mass index, frequency of overweight, waist circumference, waist-to-height ratio, insulin, glucose, homeostatic model assessment for insulin resistance, triglycerides, triglycerides/glucose index, and triglycerides-to-HDL-C were higher among insulin-resistant boys and girls. Moderate correlation of all indicators (waist-to-height ratio, triglycerides/glucose index, and triglycerides-to-HDL-C ratio) with homeostatic model assessment for insulin resistance was observed for both sexes. The areas under the receiver operational characteristic curves were similar between waist-to-height ratio and biochemical markers. The indicators provided similar discriminatory power for insulin resistance. However, taking into account the cost-benefit ratio, the authors suggest that waist-to-height ratio may be a useful tool to provide screening for insulin resistance in pediatric populations. Copyright © 2018 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

  15. Molding compound trends in a denser packaging world: Qualification tests and reliability concerns

    Science.gov (United States)

    Nguyen, L. T.; Lo, R. H. Y.; Chen, A. S.; Belani, J. G.

    1993-12-01

    Molding compound development has traditionally been driven by the memory market, then subsequent applications filter down to other IC technologies such as logic, analog, and ASIC. However, this strategy has changed lately with the introduction of thin packages such as PQFP & TSOP. Rather than targeting a compound for a family of IC such as DRAM or SRAM, compound development efforts are now focused at specific classes of packages. The configurations of these thin packages impose new functional requirements that need to be revisited to provide the optimized combination of properties. The evolution of qualification tests mirrors the advances in epoxy and compounding technologies. From the first standard novolac-based epoxies of the 1970s to the latest 3(sup rd)-generation ultra-low stress materials, longer test times at increasingly harsher environments were achieved. This paper benchmarks the current reliability tests used by the electronic industry, examines those tests that affect and are affected by the molding compounds, discusses the relevance of accelerated testing, and addresses the major reliability issues facing current molding compound development efforts. Six compound-related reliability concerns were selected: moldability, package stresses, package cracking, halogen-induced intermetallic growth at bond pads, moisture-induced corrosion, and interfacial delamination. Causes of each failure type are surveyed and remedies are recommended. Accelerated tests are designed to apply to a limited quantity of devices, bias, or environmental conditions larger than usual ratings, to intensify failure mechanisms that would occur under normal operating conditions. The observed behavior is then extrapolated from the lot to the entire population. Emphasis is on compressing the time necessary to obtain reliability data. This approach has two main drawbacks. With increasingly complex devices, even accelerated tests are expensive. And with new technologies, it becomes

  16. Distribution of defects in wind turbine blades and reliability assessment of blades containing defects

    DEFF Research Database (Denmark)

    Stensgaard Toft, Henrik; Branner, Kim; Berring, Peter

    2009-01-01

    on the assumption that one error in the production process tends to trigger several defects. For both models additional information about number, type and size of the defects is included as stochastic variables. The probability of failure for a wind turbine blade will not only depend on variations in the material......In the present paper two stochastic models for the distribution of defects in wind turbine blades are proposed. The first model assumes that the individual defects are completely randomly distributed in the blade. The second model assumes that the defects occur in clusters of different size based...... properties and the load but also on potential defects in the blades. As a numerical example the probability of failure is calculated for the main spar both with and without defects in terms of delaminations. The delaminations increase the probability of failure compared to a perfect blade, but by applying...

  17. Humidity resistant hydrogenated carbon nitride films

    Czech Academy of Sciences Publication Activity Database

    Mikmeková, Eliška; Polčák, J.; Sobota, Jaroslav; Müllerová, Ilona; Peřina, Vratislav; Caha, O.

    2013-01-01

    Roč. 275, 15 June (2013), s. 7-13 ISSN 0169-4332 R&D Projects: GA MŠk ED0017/01/01 Institutional support: RVO:68081731 ; RVO:61389005 Keywords : thin films * corrosion behanior * delamination * stress Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering; BH - Optics, Masers, Lasers (UJF-V) Impact factor: 2.538, year: 2013

  18. effect of uncertainty on the fatigue reliability of reinforced concrete ...

    African Journals Online (AJOL)

    In this paper, a reliability time-variant fatigue analysis and uncertainty effect on the serviceability of reinforced concrete bridge deck was carried out. A simply supported 15m bridge deck was specifically used for the investigation. Mathematical models were developed and the uncertainties in structural resistance, applied ...

  19. On Improving Reliability of SRAM-Based Physically Unclonable Functions

    Directory of Open Access Journals (Sweden)

    Arunkumar Vijayakumar

    2017-01-01

    Full Text Available Physically unclonable functions (PUFs have been touted for their inherent resistance to invasive attacks and low cost in providing a hardware root of trust for various security applications. SRAM PUFs in particular are popular in industry for key/ID generation. Due to intrinsic process variations, SRAM cells, ideally, tend to have the same start-up behavior. SRAM PUFs exploit this start-up behavior. Unfortunately, not all SRAM cells exhibit reliable start-up behavior due to noise susceptibility. Hence, design enhancements are needed for improving reliability. Some of the proposed enhancements in literature include fuzzy extraction, error-correcting codes and voting mechanisms. All enhancements involve a trade-off between area/power/performance overhead and PUF reliability. This paper presents a design enhancement technique for reliability that improves upon previous solutions. We present simulation results to quantify improvement in SRAM PUF reliability and efficiency. The proposed technique is shown to generate a 128-bit key in ≤0.2 μ s at an area estimate of 4538 μ m 2 with error rate as low as 10 − 6 for intrinsic error probability of 15%.

  20. Criteriom of efficiency of thermometric systems with increased reliability

    International Nuclear Information System (INIS)

    Sal'nikov, N.L.; Filimonov, E.V.

    1995-01-01

    Problems on metrological reliability of thermometric systems, intended for temperature regime control at nuclear power facilities are discussed. Thermoelectrical converters and resistance thermoconverters are the most utilized sources of thermometric information at nuclear power plants. Two or more transducers are proposed to be unified in one measurement system in order to increase the accuracy of temperature measurements through obtaining surplus values. Two versions of thermometric systems organization are considered. The first system combined various-type temperature transducers whereas the second system consists of two similar-type transducers. It is established that thermometric systems with various-type transducers are characterized by higher metrological reliability. 3 refs.; 2 figs

  1. Effect of abnormal notochord delamination on hindgut development in the Adriamycin mouse model.

    Science.gov (United States)

    Sato, Hideaki; Hajduk, Piotr; Furuta, Shigeyuki; Wakisaka, Munechika; Murphy, Paula; Puri, Prem; Kitagawa, Hiroaki

    2013-11-01

    Adriamycin mouse model (AMM) is a model of VACTERL anomalies. Sonic hedgehog (Shh) pathway, sourced by the notochord, is implicated of anorectal malformations. We hypothesized hindgut anomalies observed in the AMM are the result of abnormal effect of the notochord. Time-mated CBA/Ca mice received two intraperitoneal injections of Adriamycin (6 mg/kg) or saline as control on embryonic day (E) 7 and 8. Fetuses were harvested from E9 to E11, stained following whole mount in situ hybridization with labeled RNA probes to detect Shh and Fork head box F1(Foxf1) transcripts. Immunolocalization with endoderm marker Hnf3β was used to visualize morphology. Embryos were scanned by OPT to obtain 3D representations of expressions. In AMM, the notochord was abnormally displaced ventrally with attachment to the hindgut endoderm in 71 % of the specimens. In 32 % of the treated embryos abnormal hindgut ended blindly in a cystic structure, and both of types were remarked in 29 % of treated embryos. Endodermal Shh and mesenchymal Foxf1 genes expression were preserved around the hindgut cystic malformation. The delamination of the developing notochord in the AMM is disrupted, which may influence signaling mechanisms from the notochord to the hindgut resulting in abnormal patterning of the hindgut.

  2. Reliability assessment of nuclear structural systems

    International Nuclear Information System (INIS)

    Reich, M.; Hwang, H.

    1983-01-01

    Reliability assessment of nuclear structural systems has been receiving more emphasis over the last few years. This paper deals with the recent progress made by the Structural Analysis Division of Brookhaven National Laboratory (BNL), in the development of a probability-based reliability analysis methodology for safety evaluation of reactor containments and other seismic category I structures. An important feature of this methodology is the incorporation of finite element analysis and random vibration theory. By utilizing this method, it is possible to evaluate the safety of nuclear structures under various static and dynamic loads in terms of limit state probability. Progress in other related areas, such as the establishment of probabilistic characteristics for various loads and structural resistance, are also described. Results of an application of the methodology to a realistic reinforced concrete containment subjected to dead and live loads, accidental internal pressures and earthquake ground accelerations are presented

  3. Reliability engineering

    International Nuclear Information System (INIS)

    Lee, Chi Woo; Kim, Sun Jin; Lee, Seung Woo; Jeong, Sang Yeong

    1993-08-01

    This book start what is reliability? such as origin of reliability problems, definition of reliability and reliability and use of reliability. It also deals with probability and calculation of reliability, reliability function and failure rate, probability distribution of reliability, assumption of MTBF, process of probability distribution, down time, maintainability and availability, break down maintenance and preventive maintenance design of reliability, design of reliability for prediction and statistics, reliability test, reliability data and design and management of reliability.

  4. Numerical analysis of a polysilicon-based resistive memory device

    KAUST Repository

    Berco, Dan

    2018-03-08

    This study investigates a conductive bridge resistive memory device based on a Cu top electrode, 10-nm polysilicon resistive switching layer and a TiN bottom electrode, by numerical analysis for $$10^{3}$$103 programming and erase simulation cycles. The low and high resistive state values in each cycle are calculated, and the analysis shows that the structure has excellent retention reliability properties. The presented Cu species density plot indicates that Cu insertion occurs almost exclusively along grain boundaries resulting in a confined isomorphic conductive filament that maintains its overall shape and electric properties during cycling. The superior reliability of this structure may thus be attributed to the relatively low amount of Cu migrating into the RSL during initial formation. In addition, the results show a good match and help to confirm experimental measurements done over a previously demonstrated device.

  5. Study of self-compliance behaviors and internal filament characteristics in intrinsic SiOx-based resistive switching memory

    International Nuclear Information System (INIS)

    Chang, Yao-Feng; Zhou, Fei; Chen, Ying-Chen; Lee, Jack C.; Fowler, Burt

    2016-01-01

    Self-compliance characteristics and reliability optimization are investigated in intrinsic unipolar silicon oxide (SiO x )-based resistive switching (RS) memory using TiW/SiO x /TiW device structures. The program window (difference between SET voltage and RESET voltage) is dependent on external series resistance, demonstrating that the SET process is due to a voltage-triggered mechanism. The program window has been optimized for program/erase disturbance immunity and reliability for circuit-level applications. The SET and RESET transitions have also been characterized using a dynamic conductivity method, which distinguishes the self-compliance behavior due to an internal series resistance effect (filament) in SiO x -based RS memory. By using a conceptual “filament/resistive gap (GAP)” model of the conductive filament and a proton exchange model with appropriate assumptions, the internal filament resistance and GAP resistance can be estimated for high- and low-resistance states (HRS and LRS), and are found to be independent of external series resistance. Our experimental results not only provide insights into potential reliability issues but also help to clarify the switching mechanisms and device operating characteristics of SiO x -based RS memory

  6. Reliability Estimation for Single-unit Ceramic Crown Restorations

    Science.gov (United States)

    Lekesiz, H.

    2014-01-01

    The objective of this study was to evaluate the potential of a survival prediction method for the assessment of ceramic dental restorations. For this purpose, fast-fracture and fatigue reliabilities for 2 bilayer (metal ceramic alloy core veneered with fluorapatite leucite glass-ceramic, d.Sign/d.Sign-67, by Ivoclar; glass-infiltrated alumina core veneered with feldspathic porcelain, VM7/In-Ceram Alumina, by Vita) and 3 monolithic (leucite-reinforced glass-ceramic, Empress, and ProCAD, by Ivoclar; lithium-disilicate glass-ceramic, Empress 2, by Ivoclar) single posterior crown restorations were predicted, and fatigue predictions were compared with the long-term clinical data presented in the literature. Both perfectly bonded and completely debonded cases were analyzed for evaluation of the influence of the adhesive/restoration bonding quality on estimations. Material constants and stress distributions required for predictions were calculated from biaxial tests and finite element analysis, respectively. Based on the predictions, In-Ceram Alumina presents the best fast-fracture resistance, and ProCAD presents a comparable resistance for perfect bonding; however, ProCAD shows a significant reduction of resistance in case of complete debonding. Nevertheless, it is still better than Empress and comparable with Empress 2. In-Ceram Alumina and d.Sign have the highest long-term reliability, with almost 100% survivability even after 10 years. When compared with clinical failure rates reported in the literature, predictions show a promising match with clinical data, and this indicates the soundness of the settings used in the proposed predictions. PMID:25048249

  7. Cavitation erosion resistance of diamond-like carbon coating on stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Feng; Jiang, Shuyun, E-mail: jiangshy@seu.edu.cn

    2014-02-15

    Two diamond-like carbon (DLC) coatings are prepared on stainless steel 304 by cathodic arc plasma deposition technology at different substrate bias voltages and arc currents (−200 V/80 A, labeled DLC-1, and −100 V/60 A, labeled DLC-2). Cavitation tests are performed by using a rotating-disk test rig to explore the cavitation erosion resistance of the DLC coating. The mass losses, surface morphologies, chemical compositions and the phase constituents of the specimens after cavitation tests are examined by using digital balance, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), respectively. The results indicate that the DLC-2 coatings can elongate the incubation period of stainless steel, leading to an excellent cavitation erosion resistance as compared to the untreated stainless steel specimens. After duration of 100 h cavitation test, serious damaged surfaces and plenty of scratches can be observed on the surfaces of the stainless steel specimens, while only a few grooves and tiny pits are observed on the DLC-2 coatings. It is concluded that, decreasing micro defects and increasing adhesion can reduce the delamination of DLC coating, and the erosion continues in the stainless steel substrate after DLC coating failure, and the eroded surface of the substrate is subjected to the combined action from cavitation erosion and slurry erosion.

  8. Calibration of Resistance Factors Needed in the LRFD Design of Driven Piles

    Science.gov (United States)

    2009-05-01

    This research project presents the calibration of resistance factors for the Load and Resistance Factor Design (LRFD) method of driven : piles driven into Louisiana soils based on reliability theory. Fifty-three square Precast-Prestressed-Concrete (P...

  9. High corrosion-resistant fuel spacers

    International Nuclear Information System (INIS)

    Yoshida, Toshimi; Takase, Iwao; Ikeda, Shinzo; Masaoka, Isao; Nakajima, Junjiro.

    1986-01-01

    Purpose: To enable manufacturing BWR fuel spacers by prior-art production process, using a zirconium-base alloy having very excellent corrosion resistance. Method: A highly improved nodular-resistant, corrosion-resistant zirconium alloy is devised by adding a slight amount of niobium, titanium and vanadium to zircaloy, of which fuel spacers are produced. That is, there can be obtained an alloy having much more excellent nodular resistance than conventional zircaloy, and free from a large change in plasticity, workability, and weldability, by adding to zirconium about 1.5 % of tin, about 0.15 % of iron, about 0.05 % of chromium, about 0.05 % of nickel, and 0.05 to 0.5 % of at least one or two kinds of niobium, titanium and vanadium. Using this zirconium-base alloy can manufacture fuel spacers by the same manufacturing process, thus improving economy and reliability. (Kamimura, M.)

  10. Reliability and service life of wood structures and buildings

    Directory of Open Access Journals (Sweden)

    Zdeňka Havířová

    2005-01-01

    Full Text Available Service life of constructions and buildings of wood is dependent on temperature and moisture conditions in layers of the building cladding where the wood framework is built in. Temperature/moisture conditions or the corresponding equilibrium moisture content (EMC of the construction show considerable effects on the functional reliability of the whole building from the viewpoint of mechanical resistance and stability (ER1, energy savings and thermal protection (ER6 and hygiene, health and environment protection (ER3. To ensure the reliability of constructions and buildings for the period of their supposed service life a more profound analysis of constructions is necessary from the aspect of a global thermal/technical evaluation.

  11. Structural reliability analysis applied to pipeline risk analysis

    Energy Technology Data Exchange (ETDEWEB)

    Gardiner, M. [GL Industrial Services, Loughborough (United Kingdom); Mendes, Renato F.; Donato, Guilherme V.P. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

    2009-07-01

    Quantitative Risk Assessment (QRA) of pipelines requires two main components to be provided. These are models of the consequences that follow from some loss of containment incident, and models for the likelihood of such incidents occurring. This paper describes how PETROBRAS have used Structural Reliability Analysis for the second of these, to provide pipeline- and location-specific predictions of failure frequency for a number of pipeline assets. This paper presents an approach to estimating failure rates for liquid and gas pipelines, using Structural Reliability Analysis (SRA) to analyze the credible basic mechanisms of failure such as corrosion and mechanical damage. SRA is a probabilistic limit state method: for a given failure mechanism it quantifies the uncertainty in parameters to mathematical models of the load-resistance state of a structure and then evaluates the probability of load exceeding resistance. SRA can be used to benefit the pipeline risk management process by optimizing in-line inspection schedules, and as part of the design process for new construction in pipeline rights of way that already contain multiple lines. A case study is presented to show how the SRA approach has recently been used on PETROBRAS pipelines and the benefits obtained from it. (author)

  12. Computational methods for structural load and resistance modeling

    Science.gov (United States)

    Thacker, B. H.; Millwater, H. R.; Harren, S. V.

    1991-01-01

    An automated capability for computing structural reliability considering uncertainties in both load and resistance variables is presented. The computations are carried out using an automated Advanced Mean Value iteration algorithm (AMV +) with performance functions involving load and resistance variables obtained by both explicit and implicit methods. A complete description of the procedures used is given as well as several illustrative examples, verified by Monte Carlo Analysis. In particular, the computational methods described in the paper are shown to be quite accurate and efficient for a material nonlinear structure considering material damage as a function of several primitive random variables. The results show clearly the effectiveness of the algorithms for computing the reliability of large-scale structural systems with a maximum number of resolutions.

  13. A criterion of the performance of thermometric systems of high metrological reliability

    International Nuclear Information System (INIS)

    Sal'nikov, N.L.; Filimonov, E.V.

    1995-01-01

    Monitoring temperature regimes is an important part of ensuring the operational safety of a nuclear power plant. Therefore, high standards are imposed upon the reliability of the primary information on the heat field of the object obtained from different sensors, and it is urgent to develop methods of evaluating the metrological reliability of these sensors. THe main sources of thermometric information at nuclear power plants are contact temperature sensors, the most widely used of these being thermoelectric converters (TEC) and thermal resistance converters (TRC)

  14. Effects of stitch density and stitch thread thickness on mode II delamination properties of Vectran stitched composites

    KAUST Repository

    Herwan, J.

    2014-11-01

    © Institute of Materials, Minerals and Mining 2014. Mode II delamination properties of Vectran stitched composites were investigated, and tabbed end notch flexural specimen testing was used to prevent premature failure. The effects of stitch density and stitch thread thickness were explored, and fibre compaction due to the stitching process was also verified. The results show that, in moderately stitched laminates (low stitch density), the improvement in GIIC was negligible. Crack bridging by the stitch threads at the crack zone were mostly compensated for the effect of fibre compaction, which reduced the GIIC values. Conversely, in densely stitched laminates (high stitch density), GIIC values were improved significantly (2·4 times higher than those of unstitched laminates). The effects of stitch thread thickness appeared to be negligible in moderately stitched laminates. For densely stitched laminates, thicker stitch thread (500 denier) possessed GIIC values that were 45·7% higher than thinner stitch thread (200 denier).

  15. Effects of stitch density and stitch thread thickness on mode II delamination properties of Vectran stitched composites

    KAUST Repository

    Herwan, J.; Kondo, A.; Morooka, S.; Watanabe, N.

    2014-01-01

    © Institute of Materials, Minerals and Mining 2014. Mode II delamination properties of Vectran stitched composites were investigated, and tabbed end notch flexural specimen testing was used to prevent premature failure. The effects of stitch density and stitch thread thickness were explored, and fibre compaction due to the stitching process was also verified. The results show that, in moderately stitched laminates (low stitch density), the improvement in GIIC was negligible. Crack bridging by the stitch threads at the crack zone were mostly compensated for the effect of fibre compaction, which reduced the GIIC values. Conversely, in densely stitched laminates (high stitch density), GIIC values were improved significantly (2·4 times higher than those of unstitched laminates). The effects of stitch thread thickness appeared to be negligible in moderately stitched laminates. For densely stitched laminates, thicker stitch thread (500 denier) possessed GIIC values that were 45·7% higher than thinner stitch thread (200 denier).

  16. Characterizations of Soil Profiles Through Electric Resistivity Ratio

    Directory of Open Access Journals (Sweden)

    Chik Z

    2015-04-01

    Full Text Available This paper presents how near surface soil characteristics are obtained through soil electric resistivity ratio from soil apparent resistivity profile. In recent advances of electrical sensors, soil apparent resistivity is implemented as nondestructive method for obtaining near surface soil profile. Although geo-electric techniques offer an improvement to traditional soil sampling methods, the resulting data are still often misinterpreted for obtaining soil characteristics through apparent electrical resistivity in the field. Because, soil resistivity as before rain and after rain are changeable due to the presence of more moisture contents in field investigations. In this study, the parameter of soil electric resistivity ratio is incorporated to obtain reliable near surface soil profiles from apparent resistivity of adjacent two layers in soil. The variations of potential differences are taken into account for using four probes method to get the soil apparent resistivity profile. The research is significant for simpler and faster soil characterizations using resistivity ratio of apparent resistivity in soil investigations.

  17. Systems reliability/structural reliability

    International Nuclear Information System (INIS)

    Green, A.E.

    1980-01-01

    The question of reliability technology using quantified techniques is considered for systems and structures. Systems reliability analysis has progressed to a viable and proven methodology whereas this has yet to be fully achieved for large scale structures. Structural loading variants over the half-time of the plant are considered to be more difficult to analyse than for systems, even though a relatively crude model may be a necessary starting point. Various reliability characteristics and environmental conditions are considered which enter this problem. The rare event situation is briefly mentioned together with aspects of proof testing and normal and upset loading conditions. (orig.)

  18. Resistive field structures for semiconductor devices and uses therof

    Science.gov (United States)

    Marinella, Matthew; DasGupta, Sandeepan; Kaplar, Robert; Baca, Albert G.

    2017-09-12

    The present disclosure relates to resistive field structures that provide improved electric field profiles when used with a semiconductor device. In particular, the resistive field structures provide a uniform electric field profile, thereby enhancing breakdown voltage and improving reliability. In example, the structure is a field cage that is configured to be resistive, in which the potential changes significantly over the distance of the cage. In another example, the structure is a resistive field plate. Using these resistive field structures, the characteristics of the electric field profile can be independently modulated from the physical parameters of the semiconductor device. Additional methods and architectures are described herein.

  19. Reliability Engineering

    International Nuclear Information System (INIS)

    Lee, Sang Yong

    1992-07-01

    This book is about reliability engineering, which describes definition and importance of reliability, development of reliability engineering, failure rate and failure probability density function about types of it, CFR and index distribution, IFR and normal distribution and Weibull distribution, maintainability and movability, reliability test and reliability assumption in index distribution type, normal distribution type and Weibull distribution type, reliability sampling test, reliability of system, design of reliability and functionality failure analysis by FTA.

  20. Deterministic and Probabilistic Analysis of NPP Communication Bridge Resistance Due to Extreme Loads

    Directory of Open Access Journals (Sweden)

    Králik Juraj

    2014-12-01

    Full Text Available This paper presents the experiences from the deterministic and probability analysis of the reliability of communication bridge structure resistance due to extreme loads - wind and earthquake. On the example of the steel bridge between two NPP buildings is considered the efficiency of the bracing systems. The advantages and disadvantages of the deterministic and probabilistic analysis of the structure resistance are discussed. The advantages of the utilization the LHS method to analyze the safety and reliability of the structures is presented

  1. Cell shunt resistance and photovoltaic module performance

    Energy Technology Data Exchange (ETDEWEB)

    McMahon, T.J.; Basso, T.S.; Rummel, S.R. [National Renewable Energy Lab., Golden, CO (United States)

    1996-05-01

    Shunt resistance of cells in photovoltaic modules can affect module power output and could indicate flawed manufacturing processes and reliability problems. The authors describe a two-terminal diagnostic method to directly measure the shunt resistance of individual cells in a series-connected module non-intrusively, without deencapsulation. Peak power efficiency vs. light intensity was measured on a 12-cell, series-connected, single crystalline module having relatively high cell shunt resistances. The module was remeasured with 0.5-, 1-, and 2-ohm resistors attached across each cell to simulate shunt resistances of several emerging technologies. Peak power efficiencies decreased dramatically at lower light levels. Using the PSpice circuit simulator, the authors verified that cell shunt and series resistances can indeed be responsible for the observed peak power efficiency vs. intensity behavior. The authors discuss the effect of basic cell diode parameters, i.e., shunt resistance, series resistance, and recombination losses, on PV module performance as a function of light intensity.

  2. Using Resistivity Measurements to Determine Anisotropy in Soil and Weathered Rock

    Directory of Open Access Journals (Sweden)

    S. Soto-Caban

    2013-08-01

    Full Text Available This study uses electrical resistivity measurements of soils and weathered rock to perform a fast and reliable evaluation of field anisotropy. Two test sites at New Concord, Ohio were used for the study. These sites are characterized by different landform and slightly east dipping limestone and siltstone formations of Pennsylvanian age. The measured resistivity ranged from 19 Ω∙m to 100 ��∙m, and varied with depth, landform, and season. The anisotropy was determined by a comparison of resistance values along the directions of strike and the dip. Measurements showed that the orientation of electrical anisotropy in the shallow ground may vary due to fluid connection, which is determined by the pore geometry in soil and rock, as well as by the direction of fluid movement. Results from this study indicated that a portable electrical resistivity meter is sensitive and reliable enough to be used for shallow ground fluid monitoring.

  3. Reliability

    OpenAIRE

    Condon, David; Revelle, William

    2017-01-01

    Separating the signal in a test from the irrelevant noise is a challenge for all measurement. Low test reliability limits test validity, attenuates important relationships, and can lead to regression artifacts. Multiple approaches to the assessment and improvement of reliability are discussed. The advantages and disadvantages of several different approaches to reliability are considered. Practical advice on how to assess reliability using open source software is provided.

  4. The Effect of Veneer Layers on the Bending Shear Strength and Delamination of Laminated Veneer Lumber (LVL) from Oil Palm Trunk (OPT)

    Science.gov (United States)

    Jamaludin, M. A.; Nordin, K.; Bahari, S. A.; Ahmad, M.

    2010-03-01

    The aim of this study was to evaluate the effects of the number of veneer layers on the bending shear strength and delamination of Laminated Veneer Lumber (LVL) from oil palm trunk (OPT). Five (5), Six (6) and Seven (7) veneer layers of OPT LVL were manufactured. The dimension of the boards was 45 cm by 45 cm by 1.9 cm. The boards were hot pressed for 13 minutes at a pressure of 31 kgf per m2. Urea formaldehyde (UF) supplied by a local adhesive manufacturer was used as the binder for the boards. The bending shear tests consisted of the edgewise and flatwise tests, whereas the delamination test consisted of the cold and hot water boil tests. The preparation of the test specimens and tests set-up was in accordance to the Japanese Standards, JAS-1991 [1]. Six replications were used for each test. The results were analyzed by Analysis of Variance (ANOVA) using the Duncan's Multiple Range Test to test for significant differences. The results indicated that as the number of layers increased the strength also increased. All the boards passed the standard. The difference in strength between the different types of samples was significant at 95 percent confidence level. Bending shear failures were primarily in the veneers. It is possible to use the boards as light weight interior building and furniture components. Over the years, the supply of quality timber resources from the natural forest has decrease as the wood-based industry experienced rapid growth. The supply of rubberwood for the furniture industry is also decreasing as a result of increase latex price. Accordingly, OPT LVL can be an alternative or supplementary raw material for the wood-based industry.

  5. Accelerated life testing and reliability of high K multilayer ceramic capacitors

    Science.gov (United States)

    Minford, W. J.

    1981-01-01

    The reliability of one lot of high K multilayer ceramic capacitors was evaluated using accelerated life testing. The degradation in insulation resistance was characterized as a function of voltage and temperature. The times to failure at a voltage-temperature stress conformed to a lognormal distribution with a standard deviation approximately 0.5.

  6. An Optical Interferometric Triaxial Displacement Sensor for Structural Health Monitoring: Characterization of Sliding and Debonding for a Delamination Process.

    Science.gov (United States)

    Zhu, Chen; Chen, Yizheng; Zhuang, Yiyang; Du, Yang; Gerald, Rex E; Tang, Yan; Huang, Jie

    2017-11-22

    This paper presents an extrinsic Fabry-Perot interferometer-based optical fiber sensor (EFPI) for measuring three-dimensional (3D) displacements, including interfacial sliding and debonding during delamination. The idea employs three spatially arranged EFPIs as the sensing elements. In our sensor, the three EFPIs are formed by three endfaces of three optical fibers and their corresponding inclined mirrors. Two coincident roof-like metallic structures are used to support the three fibers and the three mirrors, respectively. Our sensor was calibrated and then used to monitor interfacial sliding and debonding between a long square brick of mortar and its support structure (i.e., a steel base plate) during the drying/curing process. This robust and easy-to-manufacture triaxial EFPI-based 3D displacement sensor has great potential in structural health monitoring, the construction industry, oil well monitoring, and geotechnology.

  7. An Optical Interferometric Triaxial Displacement Sensor for Structural Health Monitoring: Characterization of Sliding and Debonding for a Delamination Process

    Directory of Open Access Journals (Sweden)

    Chen Zhu

    2017-11-01

    Full Text Available This paper presents an extrinsic Fabry–Perot interferometer-based optical fiber sensor (EFPI for measuring three-dimensional (3D displacements, including interfacial sliding and debonding during delamination. The idea employs three spatially arranged EFPIs as the sensing elements. In our sensor, the three EFPIs are formed by three endfaces of three optical fibers and their corresponding inclined mirrors. Two coincident roof-like metallic structures are used to support the three fibers and the three mirrors, respectively. Our sensor was calibrated and then used to monitor interfacial sliding and debonding between a long square brick of mortar and its support structure (i.e., a steel base plate during the drying/curing process. This robust and easy-to-manufacture triaxial EFPI-based 3D displacement sensor has great potential in structural health monitoring, the construction industry, oil well monitoring, and geotechnology.

  8. Hydroxyapatite/poly(epsilon-caprolactone) double coating on magnesium for enhanced corrosion resistance and coating flexibility.

    Science.gov (United States)

    Jo, Ji-Hoon; Li, Yuanlong; Kim, Sae-Mi; Kim, Hyoun-Ee; Koh, Young-Hag

    2013-11-01

    Hydroxyapatite was deposited on pure magnesium (Mg) with a flexible poly(ε-caprolactone) interlayer to reduce the corrosion rate of Mg and enhance coating flexibility. The poly(ε-caprolactone) interlayer was uniformly coated on Mg by a spraying method, followed by hydroxyapatite deposition on the poly(ε-caprolactone) using an aerosol deposition method. In scanning electron microscopy observations, inorganic/organic composite-like structure was observed between the hydroxyapatite and poly(ε-caprolactone) layers, resulting from the collisions of hydroxyapatite particles into the poly(ε-caprolactone) matrix at the initial stage of the aerosol deposition. The corrosion resistance of the coated Mg was examined using potentiodynamic polarization tests. The hydroxyapatite/poly(ε-caprolactone) double coating remarkably improved the corrosion resistance of Mg in Hank's solution. In the in vitro cell tests, the coated Mg showed better cell adhesion compared with the bare Mg due to the reduced corrosion rate and enhanced biocompatibility. The stability and flexibility of hydroxyapatite/poly(ε-caprolactone) double coating was investigated by scanning electron microscopy inspections after the coated Mg was deformed. The hydroxyapatite coating on the poly(ε-caprolactone) interlayer revealed enhanced coating stability and flexibility without cracking or delamination during bending and stretching compared with the hydroxyapatite single coating. These results demonstrated that the hydroxyapatite/poly(ε-caprolactone) double coating significantly improved the surface corrosion resistance of Mg and enhanced coating flexibility for use of Mg as a biodegradable implant.

  9. Analytical method for establishing indentation rolling resistance

    Science.gov (United States)

    Gładysiewicz, Lech; Konieczna, Martyna

    2018-01-01

    Belt conveyors are highly reliable machines able to work in special operating conditions. Harsh environment, long distance of transporting and great mass of transported martials are cause of high energy usage. That is why research in the field of belt conveyor transportation nowadays focuses on reducing the power consumption without lowering their efficiency. In this paper, previous methods for testing rolling resistance are described, and new method designed by authors was presented. New method of testing rolling resistance is quite simple and inexpensive. Moreover it allows to conduct the experimental tests of the impact of different parameters on the value of indentation rolling resistance such as core design, cover thickness, ambient temperature, idler travel frequency, or load value as well. Finally results of tests of relationship between rolling resistance and idler travel frequency and between rolling resistance and idler travel speed was presented.

  10. Analytical and clinical performance characteristics of the Abbott RealTime MTB RIF/INH Resistance, an assay for the detection of rifampicin and isoniazid resistant Mycobacterium tuberculosis in pulmonary specimens.

    Science.gov (United States)

    Kostera, Joshua; Leckie, Gregor; Tang, Ning; Lampinen, John; Szostak, Magdalena; Abravaya, Klara; Wang, Hong

    2016-12-01

    Clinical management of drug-resistant tuberculosis patients continues to present significant challenges to global health. To tackle these challenges, the Abbott RealTime MTB RIF/INH Resistance assay was developed to accelerate the diagnosis of rifampicin and/or isoniazid resistant tuberculosis to within a day. This article summarizes the performance of the Abbott RealTime MTB RIF/INH Resistance assay; including reliability, analytical sensitivity, and clinical sensitivity/specificity as compared to Cepheid GeneXpert MTB/RIF version 1.0 and Hain MTBDRplus version 2.0. The limit of detection (LOD) of the Abbott RealTime MTB RIF/INH Resistance assay was determined to be 32 colony forming units/milliliter (cfu/mL) using the Mycobacterium tuberculosis (MTB) strain H37Rv cell line. For rifampicin resistance detection, the Abbott RealTime MTB RIF/INH Resistance assay demonstrated statistically equivalent clinical sensitivity and specificity as compared to Cepheid GeneXpert MTB/RIF. For isoniazid resistance detection, the assay demonstrated statistically equivalent clinical sensitivity and specificity as compared to Hain MTBDRplus. The performance data presented herein demonstrate that the Abbott RealTime MTB RIF/INH Resistance assay is a sensitive, robust, and reliable test for realtime simultaneous detection of first line anti-tuberculosis antibiotics rifampicin and isoniazid in patient specimens. Copyright © 2016 The Author. Published by Elsevier Ltd.. All rights reserved.

  11. Reliability of spring interconnects for high channel-count polyimide electrode arrays

    Science.gov (United States)

    Khan, Sharif; Ordonez, Juan Sebastian; Stieglitz, Thomas

    2018-05-01

    Active neural implants with a high channel-count need robust and reliable operational assembly for the targeted environment in order to be classified as viable fully implantable systems. The discrete functionality of the electrode array and the implant electronics is vital for intact assembly. A critical interface exists at the interconnection sites between the electrode array and the implant electronics, especially in hybrid assemblies (e.g. retinal implants) where electrodes and electronics are not on the same substrate. Since the interconnects in such assemblies cannot be hermetically sealed, reliable protection against the physiological environment is essential for delivering high insulation resistance and low defusibility of salt ions, which are limited in complexity by current assembly techniques. This work reports on a combination of spring-type interconnects on a polyimide array with silicone rubber gasket insulation for chronically active implantable systems. The spring design of the interconnects on the backend of the electrode array compensates for the uniform thickness of the sandwiched gasket during bonding in assembly and relieves the propagation of extrinsic stresses to the bulk polyimide substrate. The contact resistance of the microflex-bonded spring interconnects with the underlying metallized ceramic test vehicles and insulation through the gasket between adjacent contacts was investigated against the MIL883 standard. The contact and insulation resistances remained stable in the exhausting environmental conditions.

  12. Long-term reliability evaluation of nuclear containments with tendon force degradation

    International Nuclear Information System (INIS)

    Kim, Sang-Hyo; Choi, Moon-Seock; Joung, Jung-Yeun; Kim, Kun-Soo

    2013-01-01

    Highlights: • A probabilistic model on long-term degradation of tendon force is developed. • By using the model, we performed reliability evaluation of nuclear containment. • The analysis is also performed for the case with the strict maintenance programme. • We showed how to satisfy the target safety in the containments facing life extension. - Abstract: The long-term reliability of nuclear containment is important for operating nuclear power plants. In particular, long-term reliability should be clarified when the service life of nuclear containment is being extended. This study focuses not only on determining the reliability of nuclear containment but also presenting the reliability improvement by strengthening the containment itself or by running a strict maintenance programme. The degradation characteristics of tendon force are estimated from the data recorded during in-service inspection of containments. A reliability analysis is conducted for a limit state of through-wall cracking, which is conservative, but most crucial limit state. The results of this analysis indicate that reliability is the lowest at 3/4 height of the containment wall. Therefore, this location is the most vulnerable for the specific limit state considered in this analysis. Furthermore, changes in structural reliability owing to an increase in the number of inspecting tendons are analysed for verifying the effect of the maintenance program's intensity on expected containment reliability. In the last part of this study, an example of obtaining target reliability of nuclear containment by strengthening its structural resistance is presented. A case study is conducted for exemplifying the effect of strengthening work on containment reliability, especially during extended service life

  13. Censoring Data for Resistance Factor Calculations in Load and Resistance Factor Design: A Preliminary Study

    Science.gov (United States)

    James W. Evans; David W. Green

    2007-01-01

    Reliability estimates for the resistance distribution of wood product properties may be made from test data where all specimens are broken (full data sets) or by using data sets where information is obtained only from the weaker pieces in the distribution (censored data). Whereas considerable information exists on property estimation from full data sets, much less...

  14. Reliability of poly 3,4-ethylenedioxythiophene strain gauge

    DEFF Research Database (Denmark)

    Mateiu, Ramona Valentina; Lillemose, Michael; Hansen, Thomas Steen

    2007-01-01

    We report on the experimentally observed reliability of the piezoresistive effect in strained poly 3,4-ethylenedioxythiophene (PEDT). PEDT is an intrinsic conductive polymer which can be patterned by conventional Cleanroom processing, and thus presents a promising material for all-polymer Microsy......We report on the experimentally observed reliability of the piezoresistive effect in strained poly 3,4-ethylenedioxythiophene (PEDT). PEDT is an intrinsic conductive polymer which can be patterned by conventional Cleanroom processing, and thus presents a promising material for all......-polymer Microsystems. The measurements are made on microfabricated test chips with PEDT resistors patterned by conventional UV-lithography and reactive ion etching (RIE). We determine a gauge factor of 3.41 ± 0.42 for the strained PEDT and we see an increase in resistivity from 1.98 · 104 X m to 2.22 · 104 X m when...

  15. Test setup for long term reliability investigation of Silicon Carbide MOSFETs

    DEFF Research Database (Denmark)

    Baker, Nick; Munk-Nielsen, Stig; Beczkowski, Szymon

    2013-01-01

    Silicon Carbide MOSFETs are now widely available and have frequently been demonstrated to offer numerous advantages over Silicon based devices. However, reliability issues remain a significant concern in their realisation in commercial power electronic systems. In this paper, a test bench...... is designed that enables an accelerated power cycling test to be performed on packaged Silicon Carbide MOSFETs (TO-247) under realistic operating conditions. An accelerated power cycling test is then performed, with on-state resistance selected as the observed parameter to detect degradation. On......-state resistance is routinely monitored online through the use of an innovative voltage measurement system. The packaged Silicon Carbide MOSFET is shown to exhibit a 25% increase in on-state resistance as the device ages throughout its lifetime, with the test still on-going....

  16. Role of an encapsulating layer for reducing resistance drift in phase change random access memory

    Directory of Open Access Journals (Sweden)

    Bo Jin

    2014-12-01

    Full Text Available Phase change random access memory (PCRAM devices exhibit a steady increase in resistance in the amorphous phase upon aging and this resistance drift phenomenon directly affects the device reliability. A stress relaxation model is used here to study the effect of a device encapsulating layer material in addressing the resistance drift phenomenon in PCRAM. The resistance drift can be increased or decreased depending on the biaxial moduli of the phase change material (YPCM and the encapsulating layer material (YELM according to the stress relationship between them in the drift regime. The proposed model suggests that the resistance drift can be effectively reduced by selecting a proper material as an encapsulating layer. Moreover, our model explains that reducing the size of the phase change material (PCM while fully reset and reducing the amorphous/crystalline ratio in PCM help to improve the resistance drift, and thus opens an avenue for highly reliable multilevel PCRAM applications.

  17. Low cost corrosion and oxidation resistant coatings for improved system reliability, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — In order to improve high-temperature oxidation and corrosion resistance of critical superalloy components in turbine engines innovative processing methods must be...

  18. Global Nuclear Fuel launches GNF{sub 3} and NSF: The most reliable BWR fuel just got better

    Energy Technology Data Exchange (ETDEWEB)

    Cantonwine, P.; Schneider, R.; Hunt, B.

    2015-11-01

    Bases on evolutionary design changes and advanced technology developed by Global Nuclear Fuel (GNF), the GNF3 fuel assembly is designed to offer customers with improved fuel economics, increased performance and flexibility in operation while maintaining the superior reliability of GNF2, the most reliable design in GNFs history. In addition to improved fuel utilization and performance, GNF3 is designed and manufactured to be more resistant to debris capture, to eliminate channel control blade interference concerns, and to exhibit to best available corrosion resistance of any boiling water reactor fuel. While delivering fuel cycle savings and reliability benefits with GNF3, GNF maintains a similar licensing and operating basis to GNF2, thereby minimizing fuel transition risks. GNF3 is available in lead use assembly quantities to customers today. Eight GNF3 lead use assemblies are in operation at two utilities in the USA GNF3 is scheduled to be available for full reloads in 2018. (Author)

  19. Reliability and service life of wood structures and buildings

    OpenAIRE

    Zdeňka Havířová; Pavel Kubů

    2005-01-01

    Service life of constructions and buildings of wood is dependent on temperature and moisture conditions in layers of the building cladding where the wood framework is built in. Temperature/moisture conditions or the corresponding equilibrium moisture content (EMC) of the construction show considerable effects on the functional reliability of the whole building from the viewpoint of mechanical resistance and stability (ER1), energy savings and thermal protection (ER6) and hygiene, health and e...

  20. Analytical method for establishing indentation rolling resistance

    Directory of Open Access Journals (Sweden)

    Gładysiewicz Lech

    2018-01-01

    Full Text Available Belt conveyors are highly reliable machines able to work in special operating conditions. Harsh environment, long distance of transporting and great mass of transported martials are cause of high energy usage. That is why research in the field of belt conveyor transportation nowadays focuses on reducing the power consumption without lowering their efficiency. In this paper, previous methods for testing rolling resistance are described, and new method designed by authors was presented. New method of testing rolling resistance is quite simple and inexpensive. Moreover it allows to conduct the experimental tests of the impact of different parameters on the value of indentation rolling resistance such as core design, cover thickness, ambient temperature, idler travel frequency, or load value as well. Finally results of tests of relationship between rolling resistance and idler travel frequency and between rolling resistance and idler travel speed was presented.

  1. Nanomechanical and in situ TEM characterization of boron carbide thin films on helium implanted substrates: Delamination, real-time cracking and substrate buckling

    Energy Technology Data Exchange (ETDEWEB)

    Framil Carpeño, David, E-mail: david.framil-carpeno@auckland.ac.nz [Department of Chemical and Materials Engineering, The University of Auckland, 20 Symonds Street, Auckland 1010 (New Zealand); Ohmura, Takahito; Zhang, Ling [Strength Design Group, Structural Materials Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Leveneur, Jérôme [National Isotope Centre, GNS Science, 30 Gracefield Road, Gracefield, Lower Hutt 5010 (New Zealand); Dickinson, Michelle [Department of Chemical and Materials Engineering, The University of Auckland, 20 Symonds Street, Auckland 1010 (New Zealand); Seal, Christopher [International Centre for Advanced Materials, The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Kennedy, John [National Isotope Centre, GNS Science, 30 Gracefield Road, Gracefield, Lower Hutt 5010 (New Zealand); Hyland, Margaret [Department of Chemical and Materials Engineering, The University of Auckland, 20 Symonds Street, Auckland 1010 (New Zealand)

    2015-07-15

    Boron carbide coatings deposited on helium-implanted and unimplanted Inconel 600 were characterized using a combination of nanoindentation and transmission electron microscopy. Real-time coating, cracking and formation of slip bands were recorded using in situ TEM-nanoindentation, allowing site specific events to be correlated with specific features in their load–displacement curves. Cross-sections through the residual indent impression showed a correlation between pop-outs in the load–displacement curves and coating delamination, which was confirmed with cyclic indentation experiments. Inconel exhibits (-11-1) and (1-1-1) twin variants in its deformed region beneath the indenter, organized in bands with a ladder-like arrangement. The nanomechanical properties of the metal–ceramic coating combinations exhibit a marked substrate effect as a consequence of helium implantation.

  2. Nanomechanical and in situ TEM characterization of boron carbide thin films on helium implanted substrates: Delamination, real-time cracking and substrate buckling

    International Nuclear Information System (INIS)

    Framil Carpeño, David; Ohmura, Takahito; Zhang, Ling; Leveneur, Jérôme; Dickinson, Michelle; Seal, Christopher; Kennedy, John; Hyland, Margaret

    2015-01-01

    Boron carbide coatings deposited on helium-implanted and unimplanted Inconel 600 were characterized using a combination of nanoindentation and transmission electron microscopy. Real-time coating, cracking and formation of slip bands were recorded using in situ TEM-nanoindentation, allowing site specific events to be correlated with specific features in their load–displacement curves. Cross-sections through the residual indent impression showed a correlation between pop-outs in the load–displacement curves and coating delamination, which was confirmed with cyclic indentation experiments. Inconel exhibits (-11-1) and (1-1-1) twin variants in its deformed region beneath the indenter, organized in bands with a ladder-like arrangement. The nanomechanical properties of the metal–ceramic coating combinations exhibit a marked substrate effect as a consequence of helium implantation

  3. Delamination of plasters applied to historical masonry walls: analysis by acoustic emission technique and numerical model

    Science.gov (United States)

    Grazzini, A.; Lacidogna, G.; Valente, S.; Accornero, F.

    2018-06-01

    Masonry walls of historical buildings are subject to rising damp effects due to capillary or rain infiltrations, which in the time produce decay and delamination of historical plasters. In the restoration of masonry buildings, the plaster detachment frequently occurs because of mechanical incompatibility in repair mortar. An innovative laboratory procedure is described for test mechanical adhesion of new repair mortars. Compression static tests were carried out on composite specimens stone block-repair mortar, which specific geometry can test the de-bonding process of mortar in adherence with a stone masonry structure. The acoustic emission (AE) technique was employed for estimating the amount of energy released from fracture propagation in adherence surface between mortar and stone. A numerical simulation was elaborated based on the cohesive crack model. The evolution of detachment process of mortar in a coupled stone brick-mortar system was analysed by triangulation of AE signals, which can improve the numerical model and predict the type of failure in the adhesion surface of repair plaster. Through the cohesive crack model, it was possible to interpret theoretically the de-bonding phenomena occurring at the interface between stone block and mortar. Therefore, the mechanical behaviour of the interface is characterized.

  4. Reliability of copper based alloys for electric resistance spot welding

    International Nuclear Information System (INIS)

    Jovanovicj, M.; Mihajlovicj, A.; Sherbedzhija, B.

    1977-01-01

    Durability of copper based alloys (B-5 and B-6) for electric resistance spot-welding was examined. The total amount of Be, Ni and Zr was up to 2 and 1 wt.% respectively. Good durability and satisfactory quality of welded spots were obtained in previous laboratory experiments carried out on the fixed spot-welding machine of an industrial type (only B-5 alloy was examined). Electrodes made of both B-5 and B-6 alloy were tested on spot-welding grips and fixed spot-welding machines in Tvornica automobila Sarajevo (TAS). The obtained results suggest that the durability of electrodes made of B-5 and B-6 alloys is more than twice better than of that used in TAS

  5. Reliability analysis of service water system under earthquake

    International Nuclear Information System (INIS)

    Yu Yu; Qian Xiaoming; Lu Xuefeng; Wang Shengfei; Niu Fenglei

    2013-01-01

    Service water system is one of the important safety systems in nuclear power plant, whose failure probability is always gained by system reliability analysis. The probability of equipment failure under the earthquake is the function of the peak acceleration of earthquake motion, while the occurrence of earthquake is of randomicity, thus the traditional fault tree method in current probability safety assessment is not powerful enough to deal with such case of conditional probability problem. An analysis frame was put forward for system reliability evaluation in seismic condition in this paper, in which Monte Carlo simulation was used to deal with conditional probability problem. Annual failure probability of service water system was calculated, and failure probability of 1.46X10 -4 per year was obtained. The analysis result is in accordance with the data which indicate equipment seismic resistance capability, and the rationality of the model is validated. (authors)

  6. Multinomial-exponential reliability function: a software reliability model

    International Nuclear Information System (INIS)

    Saiz de Bustamante, Amalio; Saiz de Bustamante, Barbara

    2003-01-01

    The multinomial-exponential reliability function (MERF) was developed during a detailed study of the software failure/correction processes. Later on MERF was approximated by a much simpler exponential reliability function (EARF), which keeps most of MERF mathematical properties, so the two functions together makes up a single reliability model. The reliability model MERF/EARF considers the software failure process as a non-homogeneous Poisson process (NHPP), and the repair (correction) process, a multinomial distribution. The model supposes that both processes are statistically independent. The paper discusses the model's theoretical basis, its mathematical properties and its application to software reliability. Nevertheless it is foreseen model applications to inspection and maintenance of physical systems. The paper includes a complete numerical example of the model application to a software reliability analysis

  7. Atomistic mechanisms of ReRAM cell operation and reliability

    Science.gov (United States)

    Pandey, Sumeet C.

    2018-01-01

    We present results from first-principles-based modeling that captures functionally important physical phenomena critical to cell materials selection, operation, and reliability for resistance-switching memory technologies. An atomic-scale description of retention, the low- and high-resistance states (RS), and the sources of intrinsic cell-level variability in ReRAM is discussed. Through the results obtained from density functional theory, non-equilibrium Green’s function, molecular dynamics, and kinetic Monte Carlo simulations; the role of variable-charge vacancy defects and metal impurities in determining the RS, the LRS-stability, and electron-conduction in such RS is reported. Although, the statistical electrical characteristics of the oxygen-vacancy (Ox-ReRAM) and conductive-bridging RAM (M-ReRAM) are notably different, the underlying similar electrochemical phenomena describing retention and formation/dissolution of RS are being discussed.

  8. Air resistance measurements on actual airplane parts

    Science.gov (United States)

    Weiselsberger, C

    1923-01-01

    For the calculation of the parasite resistance of an airplane, a knowledge of the resistance of the individual structural and accessory parts is necessary. The most reliable basis for this is given by tests with actual airplane parts at airspeeds which occur in practice. The data given here relate to the landing gear of a Siemanms-Schuckert DI airplane; the landing gear of a 'Luftfahrzeug-Gesellschaft' airplane (type Roland Dlla); landing gear of a 'Flugzeugbau Friedrichshafen' G airplane; a machine gun, and the exhaust manifold of a 269 HP engine.

  9. The clinical consequences of antimicrobial resistance.

    Science.gov (United States)

    Rice, Louis B

    2009-10-01

    The continued evolution of antimicrobial resistance in the hospital and more recently in the community threatens to seriously compromise our ability to treat serious infections. The major success of the seven-valent Streptococcus pneumoniae vaccine at reducing both infection and resistance has been followed by the emergence of previously minor serotypes that express multiresistance. The almost universal activity of cephalosporins and fluoroquinolones against community Escherichia coli strains has been compromised by the spread of CTX-M beta-lactamase-producing, fluoroquinolone-resistant strains, and the emergence of community-onset methicillin-resistant Staphylococcus aureus, particularly in the United States, has forced us to re-think our empirical treatment guidelines for skin and soft-tissue infections. Finally, our most potent and reliable class of antibiotics, the carbapenems, is compromised by the growth, primarily in intensive care units, of multiresistant Klebsiella pneumoniae, Acinetobacter baumanni, and Pseudomonas aeruginosa. The lack of a robust pipeline of new agents, particularly against resistant Gram-negative bacteria, emphasizes the importance of optimizing our use of current antimicrobials and promoting strict adherence to established infection control practices.

  10. Reliability analysis of component-level redundant topologies for solid-state fault current limiter

    Science.gov (United States)

    Farhadi, Masoud; Abapour, Mehdi; Mohammadi-Ivatloo, Behnam

    2018-04-01

    Experience shows that semiconductor switches in power electronics systems are the most vulnerable components. One of the most common ways to solve this reliability challenge is component-level redundant design. There are four possible configurations for the redundant design in component level. This article presents a comparative reliability analysis between different component-level redundant designs for solid-state fault current limiter. The aim of the proposed analysis is to determine the more reliable component-level redundant configuration. The mean time to failure (MTTF) is used as the reliability parameter. Considering both fault types (open circuit and short circuit), the MTTFs of different configurations are calculated. It is demonstrated that more reliable configuration depends on the junction temperature of the semiconductor switches in the steady state. That junction temperature is a function of (i) ambient temperature, (ii) power loss of the semiconductor switch and (iii) thermal resistance of heat sink. Also, results' sensitivity to each parameter is investigated. The results show that in different conditions, various configurations have higher reliability. The experimental results are presented to clarify the theory and feasibility of the proposed approaches. At last, levelised costs of different configurations are analysed for a fair comparison.

  11. reliability reliability

    African Journals Online (AJOL)

    eobe

    Corresponding author, Tel: +234-703. RELIABILITY .... V , , given by the code of practice. However, checks must .... an optimization procedure over the failure domain F corresponding .... of Concrete Members based on Utility Theory,. Technical ...

  12. Measuring reliability under epistemic uncertainty: Review on non-probabilistic reliability metrics

    Directory of Open Access Journals (Sweden)

    Kang Rui

    2016-06-01

    Full Text Available In this paper, a systematic review of non-probabilistic reliability metrics is conducted to assist the selection of appropriate reliability metrics to model the influence of epistemic uncertainty. Five frequently used non-probabilistic reliability metrics are critically reviewed, i.e., evidence-theory-based reliability metrics, interval-analysis-based reliability metrics, fuzzy-interval-analysis-based reliability metrics, possibility-theory-based reliability metrics (posbist reliability and uncertainty-theory-based reliability metrics (belief reliability. It is pointed out that a qualified reliability metric that is able to consider the effect of epistemic uncertainty needs to (1 compensate the conservatism in the estimations of the component-level reliability metrics caused by epistemic uncertainty, and (2 satisfy the duality axiom, otherwise it might lead to paradoxical and confusing results in engineering applications. The five commonly used non-probabilistic reliability metrics are compared in terms of these two properties, and the comparison can serve as a basis for the selection of the appropriate reliability metrics.

  13. Reliability Approach of a Compressor System using Reliability Block ...

    African Journals Online (AJOL)

    pc

    2018-03-05

    Mar 5, 2018 ... This paper presents a reliability analysis of such a system using reliability ... Keywords-compressor system, reliability, reliability block diagram, RBD .... the same structure has been kept with the three subsystems: air flow, oil flow and .... and Safety in Engineering Design", Springer, 2009. [3] P. O'Connor ...

  14. Frontiers of reliability

    CERN Document Server

    Basu, Asit P; Basu, Sujit K

    1998-01-01

    This volume presents recent results in reliability theory by leading experts in the world. It will prove valuable for researchers, and users of reliability theory. It consists of refereed invited papers on a broad spectrum of topics in reliability. The subjects covered include Bayesian reliability, Bayesian reliability modeling, confounding in a series system, DF tests, Edgeworth approximation to reliability, estimation under random censoring, fault tree reduction for reliability, inference about changes in hazard rates, information theory and reliability, mixture experiment, mixture of Weibul

  15. Reliability improvement in GaN HEMT power device using a field plate approach

    Science.gov (United States)

    Wu, Wen-Hao; Lin, Yueh-Chin; Chin, Ping-Chieh; Hsu, Chia-Chieh; Lee, Jin-Hwa; Liu, Shih-Chien; Maa, Jer-shen; Iwai, Hiroshi; Chang, Edward Yi; Hsu, Heng-Tung

    2017-07-01

    This study investigates the effect of implementing a field plate on a GaN high-electron-mobility transistor (HEMT) to improve power device reliability. The results indicate that the field plate structure reduces the peak electrical field and interface traps in the device, resulting in higher breakdown voltage, lower leakage current, smaller current collapse, and better threshold voltage control. Furthermore, after high voltage stress, steady dynamic on-resistance and gate capacitance degradation improvement were observed for the device with the field plate. This demonstrates that GaN device reliability can be improved by using the field plate approach.

  16. Software reliability

    CERN Document Server

    Bendell, A

    1986-01-01

    Software Reliability reviews some fundamental issues of software reliability as well as the techniques, models, and metrics used to predict the reliability of software. Topics covered include fault avoidance, fault removal, and fault tolerance, along with statistical methods for the objective assessment of predictive accuracy. Development cost models and life-cycle cost models are also discussed. This book is divided into eight sections and begins with a chapter on adaptive modeling used to predict software reliability, followed by a discussion on failure rate in software reliability growth mo

  17. Methodology for assessing the probability of corrosion in concrete structures on the basis of half-cell potential and concrete resistivity measurements.

    Science.gov (United States)

    Sadowski, Lukasz

    2013-01-01

    In recent years, the corrosion of steel reinforcement has become a major problem in the construction industry. Therefore, much attention has been given to developing methods of predicting the service life of reinforced concrete structures. The progress of corrosion cannot be visually assessed until a crack or a delamination appears. The corrosion process can be tracked using several electrochemical techniques. Most commonly the half-cell potential measurement technique is used for this purpose. However, it is generally accepted that it should be supplemented with other techniques. Hence, a methodology for assessing the probability of corrosion in concrete slabs by means of a combination of two methods, that is, the half-cell potential method and the concrete resistivity method, is proposed. An assessment of the probability of corrosion in reinforced concrete structures carried out using the proposed methodology is presented. 200 mm thick 750 mm  ×  750 mm reinforced concrete slab specimens were investigated. Potential E corr and concrete resistivity ρ in each point of the applied grid were measured. The experimental results indicate that the proposed methodology can be successfully used to assess the probability of corrosion in concrete structures.

  18. Methodology for Assessing the Probability of Corrosion in Concrete Structures on the Basis of Half-Cell Potential and Concrete Resistivity Measurements

    Directory of Open Access Journals (Sweden)

    Lukasz Sadowski

    2013-01-01

    Full Text Available In recent years, the corrosion of steel reinforcement has become a major problem in the construction industry. Therefore, much attention has been given to developing methods of predicting the service life of reinforced concrete structures. The progress of corrosion cannot be visually assessed until a crack or a delamination appears. The corrosion process can be tracked using several electrochemical techniques. Most commonly the half-cell potential measurement technique is used for this purpose. However, it is generally accepted that it should be supplemented with other techniques. Hence, a methodology for assessing the probability of corrosion in concrete slabs by means of a combination of two methods, that is, the half-cell potential method and the concrete resistivity method, is proposed. An assessment of the probability of corrosion in reinforced concrete structures carried out using the proposed methodology is presented. 200 mm thick 750 mm  ×  750 mm reinforced concrete slab specimens were investigated. Potential Ecorr and concrete resistivity ρ in each point of the applied grid were measured. The experimental results indicate that the proposed methodology can be successfully used to assess the probability of corrosion in concrete structures.

  19. A Flexible Stretchable Hydrogel Electrolyte for Healable All-in-One Configured Supercapacitors.

    Science.gov (United States)

    Guo, Ying; Zheng, Kaiqiang; Wan, Pengbo

    2018-04-01

    The development of integrated high-performance supercapacitors with all-in-one configuration, excellent flexibility and autonomously intrinsic self-healability, and without the extra healable film layers, is still tremendously challenging. Compared to the sandwich-like laminated structures of supercapacitors with augmented interfacial contact resistance, the flexible healable integrated supercapacitor with all-in-one structure could theoretically improve their interfacial contact resistance and energy densities, simplify the tedious device assembly process, prolong the lifetime, and avoid the displacement and delamination of multilayered configurations under deformations. Herein, a flexible healable all-in-one configured supercapacitor with excellent flexibility and reliable self-healing ability by avoiding the extra healable film substrates and the postassembled sandwich-like laminated structures is developed. The healable all-in-one configured supercapacitor is prepared from in situ polymerization and deposition of nanocomposites electrode materials onto the two-sided faces of the self-healing hydrogel electrolyte separator. The self-healing hydrogel film is obtained from the physically crosslinked hydrogel with enormous hydrogen bonds, which can endow the healable capability through dynamic hydrogen bonding. The assembled all-in-one configured supercapacitor exhibits enhanced capacitive performance, good cycling stability, reliable self-healing capability, and excellent flexibility. It holds broad prospects for obtaining various flexible healable all-in-one configured supercapacitors for working as portable energy storage devices in wearable electronics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. System Reliability Engineering

    International Nuclear Information System (INIS)

    Lim, Tae Jin

    2005-02-01

    This book tells of reliability engineering, which includes quality and reliability, reliability data, importance of reliability engineering, reliability and measure, the poisson process like goodness of fit test and the poisson arrival model, reliability estimation like exponential distribution, reliability of systems, availability, preventive maintenance such as replacement policies, minimal repair policy, shock models, spares, group maintenance and periodic inspection, analysis of common cause failure, and analysis model of repair effect.

  1. Thickness effect of ultra-thin Ta2O5 resistance switching layer in 28 nm-diameter memory cell

    Science.gov (United States)

    Park, Tae Hyung; Song, Seul Ji; Kim, Hae Jin; Kim, Soo Gil; Chung, Suock; Kim, Beom Yong; Lee, Kee Jeung; Kim, Kyung Min; Choi, Byung Joon; Hwang, Cheol Seong

    2015-11-01

    Resistance switching (RS) devices with ultra-thin Ta2O5 switching layer (0.5-2.0 nm) with a cell diameter of 28 nm were fabricated. The performance of the devices was tested by voltage-driven current—voltage (I-V) sweep and closed-loop pulse switching (CLPS) tests. A Ta layer was placed beneath the Ta2O5 switching layer to act as an oxygen vacancy reservoir. The device with the smallest Ta2O5 thickness (0.5 nm) showed normal switching properties with gradual change in resistance in I-V sweep or CLPS and high reliability. By contrast, other devices with higher Ta2O5 thickness (1.0-2.0 nm) showed abrupt switching with several abnormal behaviours, degraded resistance distribution, especially in high resistance state, and much lower reliability performance. A single conical or hour-glass shaped double conical conducting filament shape was conceived to explain these behavioural differences that depended on the Ta2O5 switching layer thickness. Loss of oxygen via lateral diffusion to the encapsulating Si3N4/SiO2 layer was suggested as the main degradation mechanism for reliability, and a method to improve reliability was also proposed.

  2. Data mining and influential analysis of gene expression data for plant resistance gene identification in tomato (Solanum lycopersicum

    Directory of Open Access Journals (Sweden)

    Francisco Torres-Avilés

    2014-03-01

    Conclusion: Application of different statistical analyses to detect potential resistance genes reliably has shown to conduct interesting results that improve knowledge on molecular mechanisms of plant resistance to pathogens.

  3. A reliability simulation language for reliability analysis

    International Nuclear Information System (INIS)

    Deans, N.D.; Miller, A.J.; Mann, D.P.

    1986-01-01

    The results of work being undertaken to develop a Reliability Description Language (RDL) which will enable reliability analysts to describe complex reliability problems in a simple, clear and unambiguous way are described. Component and system features can be stated in a formal manner and subsequently used, along with control statements to form a structured program. The program can be compiled and executed on a general-purpose computer or special-purpose simulator. (DG)

  4. A study of operational and testing reliability in software reliability analysis

    International Nuclear Information System (INIS)

    Yang, B.; Xie, M.

    2000-01-01

    Software reliability is an important aspect of any complex equipment today. Software reliability is usually estimated based on reliability models such as nonhomogeneous Poisson process (NHPP) models. Software systems are improving in testing phase, while it normally does not change in operational phase. Depending on whether the reliability is to be predicted for testing phase or operation phase, different measure should be used. In this paper, two different reliability concepts, namely, the operational reliability and the testing reliability, are clarified and studied in detail. These concepts have been mixed up or even misused in some existing literature. Using different reliability concept will lead to different reliability values obtained and it will further lead to different reliability-based decisions made. The difference of the estimated reliabilities is studied and the effect on the optimal release time is investigated

  5. Human reliability

    International Nuclear Information System (INIS)

    Embrey, D.E.

    1987-01-01

    Concepts and techniques of human reliability have been developed and are used mostly in probabilistic risk assessment. For this, the major application of human reliability assessment has been to identify the human errors which have a significant effect on the overall safety of the system and to quantify the probability of their occurrence. Some of the major issues within human reliability studies are reviewed and it is shown how these are applied to the assessment of human failures in systems. This is done under the following headings; models of human performance used in human reliability assessment, the nature of human error, classification of errors in man-machine systems, practical aspects, human reliability modelling in complex situations, quantification and examination of human reliability, judgement based approaches, holistic techniques and decision analytic approaches. (UK)

  6. Diversity and antibiotic resistance of uropathogenic bacteria from ...

    African Journals Online (AJOL)

    Background: Urinary tract infections (UTI) are one of the major causes of prescribing and antibiotic consumption. In order to use the best antibiotic treatment for their patients, reliable and recent data about epidemiology and antibiotic resistance profile of uropathogenic bacteria must be available for clinicians. Therefore ...

  7. Reliability Calculations

    DEFF Research Database (Denmark)

    Petersen, Kurt Erling

    1986-01-01

    Risk and reliability analysis is increasingly being used in evaluations of plant safety and plant reliability. The analysis can be performed either during the design process or during the operation time, with the purpose to improve the safety or the reliability. Due to plant complexity and safety...... and availability requirements, sophisticated tools, which are flexible and efficient, are needed. Such tools have been developed in the last 20 years and they have to be continuously refined to meet the growing requirements. Two different areas of application were analysed. In structural reliability probabilistic...... approaches have been introduced in some cases for the calculation of the reliability of structures or components. A new computer program has been developed based upon numerical integration in several variables. In systems reliability Monte Carlo simulation programs are used especially in analysis of very...

  8. Reliability in the utility computing era: Towards reliable Fog computing

    DEFF Research Database (Denmark)

    Madsen, Henrik; Burtschy, Bernard; Albeanu, G.

    2013-01-01

    This paper considers current paradigms in computing and outlines the most important aspects concerning their reliability. The Fog computing paradigm as a non-trivial extension of the Cloud is considered and the reliability of the networks of smart devices are discussed. Combining the reliability...... requirements of grid and cloud paradigms with the reliability requirements of networks of sensor and actuators it follows that designing a reliable Fog computing platform is feasible....

  9. Dependent systems reliability estimation by structural reliability approach

    DEFF Research Database (Denmark)

    Kostandyan, Erik; Sørensen, John Dalsgaard

    2014-01-01

    Estimation of system reliability by classical system reliability methods generally assumes that the components are statistically independent, thus limiting its applicability in many practical situations. A method is proposed for estimation of the system reliability with dependent components, where...... the leading failure mechanism(s) is described by physics of failure model(s). The proposed method is based on structural reliability techniques and accounts for both statistical and failure effect correlations. It is assumed that failure of any component is due to increasing damage (fatigue phenomena...... identification. Application of the proposed method can be found in many real world systems....

  10. Influence of 12% Cr martensite steel quality on power generation reliability

    International Nuclear Information System (INIS)

    Smolenska, H.; Labanowski, J.; Cwiek, J.; Glowacka, M.; Serbinski, W.

    2001-01-01

    Influence of manufacturing process and heat treatment on microstructure and mechanical properties of 12% Cr heat resistance martensitic steels has been discussed. These steels are used for elevated temperatures applications like: heat and power plants, chemical and petrochemical installations. Some cases of manufacturing mistakes of steam pipelines and turbine blades had been presented. These mistakes led to imperfect microstructure resulting in reduced lifetime and insufficient reliability of installations. (author)

  11. Reliable and Damage-Free Estimation of Resistivity of ZnO Thin Films for Photovoltaic Applications Using Photoluminescence Technique

    Directory of Open Access Journals (Sweden)

    N. Poornima

    2013-01-01

    Full Text Available This work projects photoluminescence (PL as an alternative technique to estimate the order of resistivity of zinc oxide (ZnO thin films. ZnO thin films, deposited using chemical spray pyrolysis (CSP by varying the deposition parameters like solvent, spray rate, pH of precursor, and so forth, have been used for this study. Variation in the deposition conditions has tremendous impact on the luminescence properties as well as resistivity. Two emissions could be recorded for all samples—the near band edge emission (NBE at 380 nm and the deep level emission (DLE at ~500 nm which are competing in nature. It is observed that the ratio of intensities of DLE to NBE (/ can be reduced by controlling oxygen incorporation in the sample. - measurements indicate that restricting oxygen incorporation reduces resistivity considerably. Variation of / and resistivity for samples prepared under different deposition conditions is similar in nature. / was always less than resistivity by an order for all samples. Thus from PL measurements alone, the order of resistivity of the samples can be estimated.

  12. Detection of Macrolide, Lincosamide and Streptogramin Resistance among Methicillin Resistant Staphylococcus aureus (MRSA in Mumbai

    Directory of Open Access Journals (Sweden)

    Arunagiri Subramanian

    2015-01-01

    Full Text Available Background: The increase in incidence of Methicillin Resistant Staphyloccocus aureus (MRSA and its extraordinary potential to develop antimicrobial resistance has highlighted the need for better agents to treat such infections. This has led to a renewed interest in use of new drugs for treatment with clindamycin and quinuprsitin-dalfopristin being the preferred choice for treatment. Aim & Objectives: This study was undertaken to detect the prevalence of MacrolideLincosamide-Streptogramin (MLS resistance among clinical isolates of MRSA.Material and Methods:Two hundred and thirty clinical isolates of S. aureus were subjected to routine antibiotic susceptibility testing including cefoxitin, erythromycin and quinupristindalfopristin. Inducible resistance to clindamycin was tested by 'D' test as per Clinical and Laboratory Standards Institute (CLSI guidelines. Results: Out of all S. aureus isolates, 93.91% were identified as MRSA. In the disc diffusion testing, 81.5% of isolates showed erythromycin resistance. Among these, the prevalence of constitutive (cMLS , inducible (iMLS b b and MS-phenotype were 35.80%, 31.82% and 32.39% respectively by the D-test method. 77.8% of isolates were resistant to quinupristin-dalfopristin and the Minimum Inhibitory Concentration (MIC ranged from 4–32 µg/ml. 89.20% of isolates were resistant to both quinupristin-dalfopristin and erythromycin of which 35.03%, 35.67% and 29.30% belonged to iMLS , cMLS and MS phenotype respectively. Conclusion: The emergence of quinupristindalfopristin resistance and MLS phenotypes brings b about the need for the simple and reliable D-test in routine diagnosis and further susceptibility testing for proper antimicrobial therapy.

  13. Diamond-like carbon coatings enhance scratch resistance of bearing surfaces for use in joint arthroplasty: hard substrates outperform soft.

    Science.gov (United States)

    Roy, Marcel E; Whiteside, Leo A; Katerberg, Brian J

    2009-05-01

    The purpose of this study was to test the hypotheses that diamond-like carbon (DLC) coatings will enhance the scratch resistance of a bearing surface in joint arthroplasty, and that a hard ceramic substrate will further enhance scratch resistance by reducing plastic deformation. We tested these hypotheses by applying a hard DLC coating to medical-grade cobalt chromium alloy (CoCr) and magnesia-stabilized zirconia (Mg-PSZ) femoral heads and performing scratch tests to determine the loads required to cause cohesive and adhesive fracture of the coating. Scratch tracks of DLC-coated and noncoated heads were then scanned by optical profilometry to determine scratch depth, width, and pile-up (raised edges), as measures of susceptibility to scratching. DLC-coated CoCr specimens exhibited cohesive coating fracture as wedge spallation at an average load of 9.74 N, whereas DLC-coated Mg-PSZ exhibited cohesive fracture as arc-tensile cracks and chipping at a significantly higher average load of 41.3 N (p coating fracture, DLC-CoCr delaminated at an average load of 35.2 N, whereas DLC-Mg-PSZ fractured by recovery spallation at a significantly higher average load of 46.8 N (p DLC-CoCr and DLC-Mg-PSZ specimens exhibited significantly shallower scratches and less pile-up than did uncoated specimens (p DLC-Mg-PSZ better resisted plastic deformation, requiring significantly higher loads for cohesive and adhesive coating fracture. These findings supported both of our hypotheses. (c) 2008 Wiley Periodicals, Inc.

  14. Analyzing the reliability of shuffle-exchange networks using reliability block diagrams

    International Nuclear Information System (INIS)

    Bistouni, Fathollah; Jahanshahi, Mohsen

    2014-01-01

    Supercomputers and multi-processor systems are comprised of thousands of processors that need to communicate in an efficient way. One reasonable solution would be the utilization of multistage interconnection networks (MINs), where the challenge is to analyze the reliability of such networks. One of the methods to increase the reliability and fault-tolerance of the MINs is use of various switching stages. Therefore, recently, the reliability of one of the most common MINs namely shuffle-exchange network (SEN) has been evaluated through the investigation on the impact of increasing the number of switching stage. Also, it is concluded that the reliability of SEN with one additional stage (SEN+) is better than SEN or SEN with two additional stages (SEN+2), even so, the reliability of SEN is better compared to SEN with two additional stages (SEN+2). Here we re-evaluate the reliability of these networks where the results of the terminal, broadcast, and network reliability analysis demonstrate that SEN+ and SEN+2 continuously outperform SEN and are very alike in terms of reliability. - Highlights: • The impact of increasing the number of stages on reliability of MINs is investigated. • The RBD method as an accurate method is used for the reliability analysis of MINs. • Complex series–parallel RBDs are used to determine the reliability of the MINs. • All measures of the reliability (i.e. terminal, broadcast, and network reliability) are analyzed. • All reliability equations will be calculated for different size N×N

  15. A review of the progress with statistical models of passive component reliability

    Energy Technology Data Exchange (ETDEWEB)

    Lydell, Bengt O. Y. [Sigma-Phase Inc., Vail (United States)

    2017-03-15

    During the past 25 years, in the context of probabilistic safety assessment, efforts have been directed towards establishment of comprehensive pipe failure event databases as a foundation for exploratory research to better understand how to effectively organize a piping reliability analysis task. The focused pipe failure database development efforts have progressed well with the development of piping reliability analysis frameworks that utilize the full body of service experience data, fracture mechanics analysis insights, expert elicitation results that are rolled into an integrated and risk-informed approach to the estimation of piping reliability parameters with full recognition of the embedded uncertainties. The discussion in this paper builds on a major collection of operating experience data (more than 11,000 pipe failure records) and the associated lessons learned from data analysis and data applications spanning three decades. The piping reliability analysis lessons learned have been obtained from the derivation of pipe leak and rupture frequencies for corrosion resistant piping in a raw water environment, loss-of-coolant-accident frequencies given degradation mitigation, high-energy pipe break analysis, moderate-energy pipe break analysis, and numerous plant-specific applications of a statistical piping reliability model framework. Conclusions are presented regarding the feasibility of determining and incorporating aging effects into probabilistic safety assessment models.

  16. A Review of the Progress with Statistical Models of Passive Component Reliability

    Directory of Open Access Journals (Sweden)

    Bengt O.Y. Lydell

    2017-03-01

    Full Text Available During the past 25 years, in the context of probabilistic safety assessment, efforts have been directed towards establishment of comprehensive pipe failure event databases as a foundation for exploratory research to better understand how to effectively organize a piping reliability analysis task. The focused pipe failure database development efforts have progressed well with the development of piping reliability analysis frameworks that utilize the full body of service experience data, fracture mechanics analysis insights, expert elicitation results that are rolled into an integrated and risk-informed approach to the estimation of piping reliability parameters with full recognition of the embedded uncertainties. The discussion in this paper builds on a major collection of operating experience data (more than 11,000 pipe failure records and the associated lessons learned from data analysis and data applications spanning three decades. The piping reliability analysis lessons learned have been obtained from the derivation of pipe leak and rupture frequencies for corrosion resistant piping in a raw water environment, loss-of-coolant-accident frequencies given degradation mitigation, high-energy pipe break analysis, moderate-energy pipe break analysis, and numerous plant-specific applications of a statistical piping reliability model framework. Conclusions are presented regarding the feasibility of determining and incorporating aging effects into probabilistic safety assessment models.

  17. A review of the progress with statistical models of passive component reliability

    International Nuclear Information System (INIS)

    Lydell, Bengt O. Y.

    2017-01-01

    During the past 25 years, in the context of probabilistic safety assessment, efforts have been directed towards establishment of comprehensive pipe failure event databases as a foundation for exploratory research to better understand how to effectively organize a piping reliability analysis task. The focused pipe failure database development efforts have progressed well with the development of piping reliability analysis frameworks that utilize the full body of service experience data, fracture mechanics analysis insights, expert elicitation results that are rolled into an integrated and risk-informed approach to the estimation of piping reliability parameters with full recognition of the embedded uncertainties. The discussion in this paper builds on a major collection of operating experience data (more than 11,000 pipe failure records) and the associated lessons learned from data analysis and data applications spanning three decades. The piping reliability analysis lessons learned have been obtained from the derivation of pipe leak and rupture frequencies for corrosion resistant piping in a raw water environment, loss-of-coolant-accident frequencies given degradation mitigation, high-energy pipe break analysis, moderate-energy pipe break analysis, and numerous plant-specific applications of a statistical piping reliability model framework. Conclusions are presented regarding the feasibility of determining and incorporating aging effects into probabilistic safety assessment models

  18. Effects of Constituents and Lay-up Configuration on Drop-Weight Tests of Fiber-Metal Laminates

    Science.gov (United States)

    Liu, Yanxiong; Liaw, Benjamin

    2010-02-01

    Impact responses and damage of various fiber-metal laminates were studied using a drop-weight instrument with the post-impact damage characteristics being evaluated through ultrasonic and mechanical sectioning techniques. The first severe failure induced by the low-velocity drop-weight impact occurred as delamination between the aluminum and fiber-epoxy layers at the non-impact side. It was followed by a visible shear crack in the outer aluminum layer on the non-impact face. Through-thickness shear cracks in the aluminum sheets and severe damage in the fiber laminated layers (including delamination between adjacent fiber-epoxy laminae with different fiber orientations) developed under higher energy impacts. The impact properties of fiber-metal laminates varied with different constituent materials and fiber orientations. Since it was punched through easily, the aramid-fiber reinforced fiber-metal laminates (ARALL) offered poorer impact resistance than the glass-fiber reinforced fiber-metal laminates (GLARE). Tougher and more ductile aluminum alloys improved the impact resistance. GLARE made of cross-ply prepregs provided better impact resistance than GLARE with unidirectional plies.

  19. Determination of electrical resistivity of dry coke beds

    Energy Technology Data Exchange (ETDEWEB)

    Eidem, P.A.; Tangstad, M.; Bakken, J.A. [NTNU, Trondheim (Norway)

    2008-02-15

    The electrical resistivity of the coke bed is of great importance when producing FeMn, SiMn, and FeCr in a submerged arc furnace. In these processes, a coke bed is situated below and around the electrode tip and consists of metallurgical coke, slag, gas, and metal droplets. Since the basic mechanisms determining the electrical resistivity of a coke bed is not yet fully understood, this investigation is focused on the resistivity of dry coke beds consisting of different carbonaceous materials, i.e., coke beds containing no slag or metal. A method that reliably compares the electrical bulk resistivity of different metallurgical cokes at 1500{sup o} C to 1600{sup o}C is developed. The apparatus is dimensioned for industrial sized materials, and the electrical resistivity of anthracite, charcoal, petroleum coke, and metallurgical coke has been measured. The resistivity at high temperatures of the Magnitogorsk coke, which has the highest resistivity of the metallurgical cokes investigated, is twice the resistivity of the Corus coke, which has the lowest electrical resistivity. Zdzieszowice and SSAB coke sort in between with decreasing resistivities in the respective order. The electrical resistivity of anthracite, charcoal, and petroleum coke is generally higher than the resistivity of the metallurgical cokes, ranging from about two to about eight times the resistivity of the Corus coke at 1450{sup o}C. The general trend is that the bulk resistivity of carbon materials decreases with increasing temperature and increasing particle size.

  20. Bayesian inference of the flow resistivity of a sound absorber and the room's influence on the Sabine absorption coefficients

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho; Choi, Sang-Hyeon; Lee, Ikjin

    2017-01-01

    A Bayesian analysis is applied to determine the flow resistivity of a porous sample and the influence of the test chamber based on measured Sabine absorption coefficient data. The Sabine absorption coefficient measured in a reverberation chamber according to ISO 354 is influenced by the test...... chamber significantly, whereas the flow resistivity is a rather reproducible material property, from which the absorptive characteristics can be calculated through reliable models. Using Sabine absorption coefficients measured in 13 European reverberation chambers, the maximum a posteriori...... and the uncertainty of the flow resistivity and the test chamber’s influence are estimated. Inclusion of more than one chamber’s absorption data helps the flow resistivity converge towards a reliable value with a standard deviation below 17%...

  1. Reliability data banks

    International Nuclear Information System (INIS)

    Cannon, A.G.; Bendell, A.

    1991-01-01

    Following an introductory chapter on Reliability, what is it, why it is needed, how it is achieved and measured, the principles of reliability data bases and analysis methodologies are the subject of the next two chapters. Achievements due to the development of data banks are mentioned for different industries in the next chapter, FACTS, a comprehensive information system for industrial safety and reliability data collection in process plants are covered next. CREDO, the Central Reliability Data Organization is described in the next chapter and is indexed separately, as is the chapter on DANTE, the fabrication reliability Data analysis system. Reliability data banks at Electricite de France and IAEA's experience in compiling a generic component reliability data base are also separately indexed. The European reliability data system, ERDS, and the development of a large data bank come next. The last three chapters look at 'Reliability data banks, - friend foe or a waste of time'? and future developments. (UK)

  2. An Introduction To Reliability

    International Nuclear Information System (INIS)

    Park, Kyoung Su

    1993-08-01

    This book introduces reliability with definition of reliability, requirement of reliability, system of life cycle and reliability, reliability and failure rate such as summary, reliability characteristic, chance failure, failure rate which changes over time, failure mode, replacement, reliability in engineering design, reliability test over assumption of failure rate, and drawing of reliability data, prediction of system reliability, conservation of system, failure such as summary and failure relay and analysis of system safety.

  3. Numerical simulating and experimental study on the woven carbon fiber-reinforced composite laminates under low-velocity impact

    Science.gov (United States)

    Liu, Hanyang; Tang, Zhanwen; Pan, Lingying; Zhao, Weidong; Sun, Baogang; Jiang, Wenge

    2016-05-01

    Impact damage has been identified as a critical form of the defects that constantly threatened the reliability of composite structures, such as those used in the aerospace structures and systems. Low energy impacts can introduce barely visible damage and cause the degradation of structural stiffness, furthermore, the flaws caused by low-velocity impact are so dangerous that they can give rise to the further extended delaminations. In order to improve the reliability and load carrying capacity of composite laminates under low-velocity impact, in this paper, the numerical simulatings and experimental studies on the woven fiber-reinforced composite laminates under low-velocity impact with impact energy 16.7J were discussed. The low velocity impact experiment was carried out through drop-weight system as the reason of inertia effect. A numerical progressive damage model was provided, in which the damages of fiber, matrix and interlamina were considered by VUMT subroutine in ABAQUS, to determine the damage modes. The Hashin failure criteria were improved to cover the failure modes of fiber failure in the directions of warp/weft and delaminations. The results of Finite Element Analysis (FEA) were compared with the experimental results of nondestructive examination including the results of ultrasonic C-scan, cross-section stereomicroscope and contact force - time history curves. It is found that the response of laminates under low-velocity impact could be divided into stages with different damage. Before the max-deformation of the laminates occurring, the matrix cracking, fiber breakage and delaminations were simulated during the impactor dropping. During the releasing and rebounding period, matrix cracking and delaminations areas kept increasing in the laminates because of the stress releasing of laminates. Finally, the simulating results showed the good agreements with the results of experiment.

  4. The operational mechanism of ferroelectric-driven organic resistive switches

    NARCIS (Netherlands)

    Kemerink, M.; Asadi, K.; Blom, P.W.M.; Leeuw, D.M. de

    2012-01-01

    The availability of a reliable memory element is crucial for the fabrication of 'plastic' logic circuits. We use numerical simulations to show that the switching mechanism of ferroelectric-driven organic resistive switches is the stray field of the polarized ferroelectric phase. The stray field

  5. The operational mechanism of ferroelectric-driven organic resistive switches

    NARCIS (Netherlands)

    Kemerink, M.; Asadi, K. (Kamal); Blom, P.W.M.; Leeuw, de D.M.

    2012-01-01

    The availability of a reliable memory element is crucial for the fabrication of ‘plastic’ logic circuits. We use numerical simulations to show that the switching mechanism of ferroelectric-driven organic resistive switches is the stray field of the polarized ferroelectric phase. The stray field

  6. The operational mechanism of ferroelectric-driven organic resistive switches

    NARCIS (Netherlands)

    Kemerink, Martijn; Asadi, Kamal; Blom, Paul W. M.; de Leeuw, Dago M.

    The availability of a reliable memory element is crucial for the fabrication of 'plastic' logic circuits. We use numerical simulations to show that the switching mechanism of ferroelectric-driven organic resistive switches is the stray field of the polarized ferroelectric phase. The stray field

  7. Improving contour accuracy and strength of reactive air brazed (RAB) ceramic/metal joints by controlling interface microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chichi; Kuhn, Bernd; Brandenberg, Joerg; Beck, Tilmann; Singheiser, Lorenz [Forschungszentrum Juelich GmbH, Institute for Energy and Climate Research (IEK), Microstructure and Properties of Materials (IEK-2), 52425 Juelich (Germany); Bobzin, Kirsten; Bagcivan, Nazlim; Kopp, Nils [Surface Engineering Institute (IOT), RWTH Aachen University, Kackertstr. 15, 52072 Aachen (Germany)

    2012-06-15

    The development of high-temperature electrochemical devices such as solid oxide fuel cells, oxygen, and hydrogen separators and gas reformers poses a great challenge in brazing technology of metal/ceramic joints. To maintain the integrity of such equipment, the resulting seals have to be stable and hermetic during continuous and cyclic high temperature operation. As a solution for joining metal and ceramic materials, reactive air brazing has gained increasing interest in recent years. This paper compares joints brazed by different filler alloys: pure Ag, AgCu, and AgAl in three different aspects: contour accuracy, room temperature delamination resistance, and corresponding microstructures of the as-brazed and fractured brazed joints. Discussion focuses on fracture mechanism and associated delamination resistance. AgAl brazed joints exhibit the most promising mechanical properties and contour accuracy. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. The application of DCPD method to evaluating dynamic J-R fracture resistance characteristics

    International Nuclear Information System (INIS)

    Yoon, Ji Hyun; Hong, Jun Hwa; Lee, Bong Sang; Chi, Se Whan; Kim, Joo Hag; Oh, Yong Jun; Kwun, Sun Chil; Oh, Jong Myung

    1999-06-01

    The reliable DCPD (Direct Current Potential Drop) test and data acquisition system were developed on the basis of analysis of various technical problems to accompanied with the application of DCPD method to J-R fracture resistance test. The test system contains electric insulation rod and high performance data acquisition system. The test and analysis method was applied to J-R fracture resistance test for SA516-Gr.70 steel for nuclear primary coolant system elbow. The reliabilities of test and analysis method were confirmed through the load-ratio method in case of dynamic loading test, and through the standard unloading compliance test in case of static loading test. (author). 17 refs., 1 tab., 18 figs

  9. The application of DCPD method to evaluating dynamic J-R fracture resistance characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Ji Hyun; Hong, Jun Hwa; Lee, Bong Sang; Chi, Se Whan; Kim, Joo Hag; Oh, Yong Jun; Kwun, Sun Chil; Oh, Jong Myung

    1999-06-01

    The reliable DCPD (Direct Current Potential Drop) test and data acquisition system were developed on the basis of analysis of various technical problems to accompanied with the application of DCPD method to J-R fracture resistance test. The test system contains electric insulation rod and high performance data acquisition system. The test and analysis method was applied to J-R fracture resistance test for SA516-Gr.70 steel for nuclear primary coolant system elbow. The reliabilities of test and analysis method were confirmed through the load-ratio method in case of dynamic loading test,and through the standard unloading compliance test in case of static loading test. (author). 17 refs., 1 tab., 18 figs.

  10. Reliability of the Quench Protection System for the LHC Superconducting Elements

    OpenAIRE

    Vergara-Fernández, A; Rodríguez-Mateos, F

    2003-01-01

    The huge energy stored in the Large Hadron Collider (LHC) could potentially cause severe damage when the superconducting state disappears (quench) if precautions are not taken. Most of the superconducting elements in this accelerator require protection in case of resistive transition. The reliability of the Quench Protection System will have a very important impact on the overall LHC performance. Existing high energy accelerators were conceived as prototypes whose main objective was not the e...

  11. System Reliability of Timber Structures

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Sørensen, John Dalsgaard

    2010-01-01

    elements, alternate load path(s) etc. in the structural design. In general these characteristics can have a positive influence on system reliability of a structure however, in Eurocodes ductility is only awarded for concrete and steel structures but not for timber structures. It is well......-know that structural systems can redistribute internal forces due to ductility of a connection, i.e. some additional loads can be carried by the structure. The same effect is also possible for reinforced concrete structures and structures of steel. However, for timber structures codes do not award that ductility......For reduction of the risk of collapse in the event of loss of structural element(s), a structural engineer may take necessary steps to design a collapse-resistant structure that is insensitive to accidental circumstances e.g. by incorporating characteristics like redundancy, ties, ductility, key...

  12. Highly Conductive and Reliable Copper-Filled Isotropically Conductive Adhesives Using Organic Acids for Oxidation Prevention

    Science.gov (United States)

    Chen, Wenjun; Deng, Dunying; Cheng, Yuanrong; Xiao, Fei

    2015-07-01

    The easy oxidation of copper is one critical obstacle to high-performance copper-filled isotropically conductive adhesives (ICAs). In this paper, a facile method to prepare highly reliable, highly conductive, and low-cost ICAs is reported. The copper fillers were treated by organic acids for oxidation prevention. Compared with ICA filled with untreated copper flakes, the ICA filled with copper flakes treated by different organic acids exhibited much lower bulk resistivity. The lowest bulk resistivity achieved was 4.5 × 10-5 Ω cm, which is comparable to that of commercially available Ag-filled ICA. After 500 h of 85°C/85% relative humidity (RH) aging, the treated ICAs showed quite stable bulk resistivity and relatively stable contact resistance. Through analyzing the results of x-ray diffraction, x-ray photoelectron spectroscopy, and thermogravimetric analysis, we found that, with the assistance of organic acids, the treated copper flakes exhibited resistance to oxidation, thus guaranteeing good performance.

  13. Reliability calculations

    International Nuclear Information System (INIS)

    Petersen, K.E.

    1986-03-01

    Risk and reliability analysis is increasingly being used in evaluations of plant safety and plant reliability. The analysis can be performed either during the design process or during the operation time, with the purpose to improve the safety or the reliability. Due to plant complexity and safety and availability requirements, sophisticated tools, which are flexible and efficient, are needed. Such tools have been developed in the last 20 years and they have to be continuously refined to meet the growing requirements. Two different areas of application were analysed. In structural reliability probabilistic approaches have been introduced in some cases for the calculation of the reliability of structures or components. A new computer program has been developed based upon numerical integration in several variables. In systems reliability Monte Carlo simulation programs are used especially in analysis of very complex systems. In order to increase the applicability of the programs variance reduction techniques can be applied to speed up the calculation process. Variance reduction techniques have been studied and procedures for implementation of importance sampling are suggested. (author)

  14. Improved design of large wind turbine blades of fibre composites (Phase 2) - Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, B.F. [Risoe National Lab., Materials Research Dept., Roskilde (Denmark); Branner, K. [Risoe National Lab., Wind Energy Dept., Roskilde (Denmark); Stang, H. [Technical Univ. of Denmark, Dept. of Civil Engineering, Kgs. Lyngby (Denmark); Jensen, H.M. [Aalborg Univ., Dept. of Building Technology and Structural Engineering (Denmark); Lund, E. [Aalborg Univ., Inst. of Mechanical Enginering (Denmark); Jacobsen, T.K. [LM glasfiber A/S, Lunderskov (Denmark); Halling, K.M. [Vestas Wind Systems A/S, Ringkoebing (Denmark)

    2005-08-01

    The major results of Phase 2 of a project concerning the development of new design methods for wind turbine blades are summarised. Finite element models were used for studying the buckling behaviour of a box girder, tested to failure in Phase 1 of this project. The deformation behaviour of a box girder section subjected to transverse forces was investigated experimentally and by modelling. Buckling-driven delamination of planar specimens was studied on experimentally and by modelling. A novel approach was proposed for the determination of mixed mode cohesive laws for large-scale crack bridging problems. The normal and shear stresses of the cohesive laws were obtained from data of the fracture resistance and the normal and tangential displacements of the cohesive zone. Delamination of a thin layer bonded to an elastic substrate close to corners and edges was also analysed. Results for the shape of the interface crack front and critical stress for steady-state delamination were obtained. (au)

  15. Black patients sustain vision loss while White and South Asian patients gain vision following delamination or segmentation surgery for tractional complications associated with proliferative diabetic retinopathy.

    Science.gov (United States)

    Mastropasqua, R; Luo, Y H-L; Cheah, Y S; Egan, C; Lewis, J J; da Cruz, L

    2017-10-01

    PurposeThis retrospective comparative case series aims to determine whether patient ethnicity (White versus South Asian versus Black) is related to the outcome of surgical treatment for traction complications of severe proliferative diabetic retinopathy (PDR).SettingMoorfields Eye Hospital London, UK.MethodsAll patients who underwent vitrectomy with, delamination and/or segmentation for PDR over a 5-year period (2009-2014) were reviewed retrospectively. Patients were divided into White, South Asian or Black groups, and their age, gender, HbA1C and type of diabetes were recorded. A total of 484 patients (253 White, 117 South Asian, 114 Black) were included. Twenty-one patients were excluded due to inadequate documentation.OutcomesLogMAR Visual acuity (converted from Snellen) (VA), was recorded pre-operatively and ~6 months post surgery (range 5-8 months). Surgical outcome was classified according to the type and duration of tamponade required post-operatively.ResultsPre-operative VA and HbA1C values were similar across all three ethnic groups (P=0.64 and 0.569, respectively). Change in VA (mean±SD) was 0.41±0.78, 0.14±0.76 and -0.26±0.57 in White, South Asian and Black patient groups respectively (PAsian patient groups.ConclusionsThis study demonstrates that Black patients on average lose vision following delamination surgery for traction complications of PDR while White and South Asian patients gain vision. The same group is also at higher risk of retaining silicone more than 6 months after surgery. This difference remains even when corrected for glycaemic control. The higher risk of visual loss and long-term retention of silicone oil in black patients requires further investigation. If these results are confirmed, surgeons should consider their patients' ethnicity before proceeding with surgical treatment of diabetic tractional detachment.

  16. Interactive reliability assessment using an integrated reliability data bank

    International Nuclear Information System (INIS)

    Allan, R.N.; Whitehead, A.M.

    1986-01-01

    The logical structure, techniques and practical application of a computer-aided technique based on a microcomputer using floppy disc Random Access Files is described. This interactive computational technique is efficient if the reliability prediction program is coupled directly to a relevant source of data to create an integrated reliability assessment/reliability data bank system. (DG)

  17. Mode I type delamination fracture toughness of YBCO coated conductor with additional Cu layer

    International Nuclear Information System (INIS)

    Miyazato, T.; Hojo, M.; Sugano, M.; Adachi, T.; Inoue, Y.; Shikimachi, K.; Hirano, N.; Nagaya, S.

    2011-01-01

    A fracture toughness test method was developed for a YBCO coated conductor with an additional Cu layer. Mode I type tests were carried out using double cantilever beam (DCB) specimens. Delamination propagated into the YBCO layer, and sometimes reached the Ag/YBCO interface. The fracture toughness for YBCO was about 10 J/m 2 . That for Ag/YBCO interface was about 100 J/m 2 . Although interlaminar fracture at a YBa 2 Cu 3 O 7-δ (YBCO)/CeO 2 interface was reported for YBCO coated conductors, this has not yet been investigated by a fracture mechanical approach. In the present study, we developed a mode I type fracture toughness test method for a YBCO coated conductor with an additional Cu layer using double cantilever beam (DCB) specimens. Fracture mechanism was investigated by microscopic observation by a scanning electron microscope (SEM), together with composition analysis by an energy dispersive X-ray spectroscope (EDS). A pre-crack introduced at the YBCO/CeO 2 interface deviated from the interface, and propagated into the YBCO layer, and sometimes reached the Ag/YBCO interface. The fracture toughness, G R , for YBCO and the Ag/YBCO interface was evaluated to be 7-10 J/m 2 and 80-120 J/m 2 , respectively. The complex stress intensity factor ratio, K 2 /K 1 , at YBCO/CeO 2 interface was evaluated to be -0.19, and this ratio controlled the formation of microcracks in the YBCO layer. The main crack propagated into the YBCO layer accompanied with the formation of microcracks.

  18. Molecular Genetics of Drug-resistance in Epilepsies

    Directory of Open Access Journals (Sweden)

    Kurupath Radhakrishnan

    2015-06-01

    Full Text Available Nearly one-third of newly diagnosed patients with epilepsy remain unresponsive to antiepileptic drugs (AEDs, etiopathogenesis of which is poorly understood. The genes encoding the proteins that regulate the pharmacokinetics such as P-glycoprotein [ABCBI], major vault protein [MVP gene] and drug metabolizing enzymes [ABCB1, ABCG2, MVP, CYP2C9, CYP2C19, CYP3A4, CYP3A5, EPHX1, UGT1A1, UGT2B7], and pharmacodynamics such as sodium channels [SCN1A, SCN2A] and GABA receptors [GABRA1, GABRA6, GABRB2, GABRG2] of AEDs are under intense investigation to unravel the mysteries of AED-resistance. However, till today, a consistent and reliable result that could help the clinician either to predict drug resistance or to overcome it has not been forthcoming. The discrepant results may be related to variations in the definition of drug-resistance, heterogeneous patient populations, ethnic variations in the frequency distribution of single nucleotide polymorphisms (SNPs and the selection of SNPs. Understanding of these limitations of existing studies, hopefully, will help in designing better studies. Nearly one-third of newly diagnosed patients with epilepsy remain unresponsive toantiepileptic drugs (AEDs, etiopathogenesis of which is poorly understood. The genesencoding the proteins that regulate the pharmacokinetics such as P-glycoprotein[ABCBI], major vault protein [MVP gene] and drug metabolizing enzymes [ABCB1,ABCG2, MVP, CYP2C9, CYP2C19, CYP3A4, CYP3A5, EPHX1, UGT1A1, UGT2B7],and pharmacodynamics such as sodium channels [SCN1A, SCN2A] and GABAreceptors [GABRA1, GABRA6, GABRB2, GABRG2] of AEDs are under intenseinvestigation to unravel the mysteries of AED-resistance. However, till today, aconsistent and reliable result that could help the clinician either to predict drugresistanceor to overcome it has not been forthcoming. The discrepant results may berelated to variations in the definition of drug-resistance, heterogeneous patientpopulations, ethnic

  19. 76 FR 23222 - Electric Reliability Organization Interpretation of Transmission Operations Reliability

    Science.gov (United States)

    2011-04-26

    ....3d 1342 (DC Cir. 2009). \\5\\ Mandatory Reliability Standards for the Bulk-Power System, Order No. 693... Reliability Standards for the Bulk-Power System. Action: FERC-725A. OMB Control No.: 1902-0244. Respondents...] Electric Reliability Organization Interpretation of Transmission Operations Reliability AGENCY: Federal...

  20. Vancomycin-resistant Enterococcus spp.: validation of susceptibility testing and in vitro activity of vancomycin, linezolid, tigecycline and daptomycin

    DEFF Research Database (Denmark)

    Rathe, Mathias; Kristensen, Lise; Ellermann-Eriksen, Svend

    2010-01-01

    Vancomycin-resistant enterococci (VRE) have emerged to become a significant nosocomial pathogen. However, detection may be challenging and treatment possibilities are limited. Reports of resistance to linezolide, daptomycin and tigecycline underline the need for reliable susceptibility testing wi...

  1. Automated finite element updating using strain data for the lifetime reliability assessment of bridges

    International Nuclear Information System (INIS)

    Okasha, Nader M.; Frangopol, Dan M.; Orcesi, André D.

    2012-01-01

    The importance of improving the understanding of the performance of structures over their lifetime under uncertainty with information obtained from structural health monitoring (SHM) has been widely recognized. However, frameworks that efficiently integrate monitoring data into the life-cycle management of structures are yet to be developed. The objective of this paper is to propose and illustrate an approach for updating the lifetime reliability of aging bridges using monitored strain data obtained from crawl tests. It is proposed to use automated finite element model updating techniques as a tool for updating the resistance parameters of the structure. In this paper, the results from crawl tests are used to update the finite element model and, in turn, update the lifetime reliability. The original and updated lifetime reliabilities are computed using advanced computational tools. The approach is illustrated on an existing bridge.

  2. 76 FR 23171 - Electric Reliability Organization Interpretations of Interconnection Reliability Operations and...

    Science.gov (United States)

    2011-04-26

    ... Reliability Standards for the Bulk-Power System, Order No. 693, FERC Stats. & Regs. ] 31,242, order on reh'g...-Power System reliability may request an interpretation of a Reliability Standard.\\7\\ The ERO's standards... information in its reliability assessments. The Reliability Coordinator must monitor Bulk Electric System...

  3. Lithospheric delamination in post-collisional setting: Evidence from intrusive magmatism from the North Qilian orogen to southern margin of the Alxa block, NW China

    Science.gov (United States)

    Zhang, Liqi; Zhang, Hongfei; Zhang, Shasha; Xiong, Ziliang; Luo, Biji; Yang, He; Pan, Fabin; Zhou, Xiaochun; Xu, Wangchun; Guo, Liang

    2017-09-01

    Post-collisional granitoids are widespread in the North Qilian and southern margin of the Alxa block and their petrogenesis can provide important insights into the lithospheric processes in a post-collisional setting. This paper carries out an integrated study of U-Pb zircon dating, geochemical and Sr-Nd-Hf isotopic compositions for five early Paleozoic intrusive plutons from the North Qilian to southern margin of the Alxa block. The geochronological and geochemical results show that their magmatism can be divided into three periods with distinct geochemical features. The early-period intrusive rocks ( 440 Ma) include the Lianhuashan (LHS) and Mengjiadawan (MJDW) granodiorites. Both of them display high Sr/Y ratios (52-91), coupled with low Y and HREE contents, implying that they were derived from partial melting of thickened lower crust, with garnet in the residue. The middle-period intrusive rocks ( 430 Ma), including the MJDW quartz diorites and Yangqiandashan (YQDS) granodiorites, are high-K calc-alkaline with low Sr/Y values. The geochemical and isotopic data suggest that they are generated from partial melting of lower crust without garnet in the residue. The late-period intrusive rocks (414-422 Ma), represented by the Shengrongsi (SRS) and Xinkaigou (XKG) plutons, are A-type or alkali-feldspar granites. They are possibly derived from partial melting of felsic crustal material under lower pressure condition. Our data show decreasing magma crystallization ages from MJDW pluton in the north and LHS pluton in the south to the SRS and XKG plutons in the central part of the study area. We suggest that such spatial and temporal variations of magmatic suites were caused by lithospheric delamination after the collision between the Central Qilian and the Alxa block. A more plausible explanation is that the delamination propagated from the margin part of the thickened lithosphere to inward beneath the North Qilian and southern margin of the Alxa block.

  4. In Search of a Time Efficient Approach to Crack and Delamination Growth Predictions in Composites

    Science.gov (United States)

    Krueger, Ronald; Carvalho, Nelson

    2016-01-01

    Analysis benchmarking was used to assess the accuracy and time efficiency of algorithms suitable for automated delamination growth analysis. First, the Floating Node Method (FNM) was introduced and its combination with a simple exponential growth law (Paris Law) and Virtual Crack Closure technique (VCCT) was discussed. Implementation of the method into a user element (UEL) in Abaqus/Standard(Registered TradeMark) was also presented. For the assessment of growth prediction capabilities, an existing benchmark case based on the Double Cantilever Beam (DCB) specimen was briefly summarized. Additionally, the development of new benchmark cases based on the Mixed-Mode Bending (MMB) specimen to assess the growth prediction capabilities under mixed-mode I/II conditions was discussed in detail. A comparison was presented, in which the benchmark cases were used to assess the existing low-cycle fatigue analysis tool in Abaqus/Standard(Registered TradeMark) in comparison to the FNM-VCCT fatigue growth analysis implementation. The low-cycle fatigue analysis tool in Abaqus/Standard(Registered TradeMark) was able to yield results that were in good agreement with the DCB benchmark example. Results for the MMB benchmark cases, however, only captured the trend correctly. The user element (FNM-VCCT) always yielded results that were in excellent agreement with all benchmark cases, at a fraction of the analysis time. The ability to assess the implementation of two methods in one finite element code illustrated the value of establishing benchmark solutions.

  5. A sampling and metagenomic sequencing-based methodology for monitoring antimicrobial resistance in swine herds

    DEFF Research Database (Denmark)

    Munk, Patrick; Dalhoff Andersen, Vibe; de Knegt, Leonardo

    2016-01-01

    Objectives Reliable methods for monitoring antimicrobial resistance (AMR) in livestock and other reservoirs are essential to understand the trends, transmission and importance of agricultural resistance. Quantification of AMR is mostly done using culture-based techniques, but metagenomic read...... mapping shows promise for quantitative resistance monitoring. Methods We evaluated the ability of: (i) MIC determination for Escherichia coli; (ii) cfu counting of E. coli; (iii) cfu counting of aerobic bacteria; and (iv) metagenomic shotgun sequencing to predict expected tetracycline resistance based...... cultivation-based techniques in terms of predicting expected tetracycline resistance based on antimicrobial consumption. Our metagenomic approach had sufficient resolution to detect antimicrobial-induced changes to individual resistance gene abundances. Pen floor manure samples were found to represent rectal...

  6. Editing plants for virus resistance using CRISPR-Cas.

    Science.gov (United States)

    Green, J C; Hu, J S

    This minireview summarizes recent advancements using the clustered regularly interspaced palindromic repeats-associated nuclease systems (CRISPR-Cas) derived from prokaryotes to breed plants resistant to DNA and RNA viruses. The CRISPR-Cas system represents a powerful tool able to edit and insert novel traits into plants precisely at chosen loci offering enormous advantages to classical breeding. Approaches to engineering plant virus resistance in both transgenic and non-transgenic plants are discussed. Iterations of the CRISPR-Cas system, FnCas9 and C2c2 capable of editing RNA in eukaryotic cells offer a particular advantage for providing resistance to RNA viruses which represent the great majority of known plant viruses. Scientists have obtained conflicting results using gene silencing technology to produce transgenic plants resistant to geminiviruses. CRISPR-Cas systems engineered in plants to target geminiviruses have consistently reduced virus accumulation providing increased resistance to virus infection. CRISPR-Cas may provide novel and reliable approaches to control geminiviruses and other ssDNA viruses such as Banana bunchy top virus (BBTV).

  7. Machinability Study on Milling Kenaf Fiber Reinforced Plastic Composite Materials using Design of Experiments

    Science.gov (United States)

    Azmi, H.; Haron, C. H. C.; Ghani, J. A.; Suhaily, M.; Yuzairi, A. R.

    2018-04-01

    The surface roughness (Ra) and delamination factor (Fd) of a milled kenaf reinforced plastic composite materials are depending on the milling parameters (spindle speed, feed rate and depth of cut). Therefore, a study was carried out to investigate the relationship between the milling parameters and their effects on a kenaf reinforced plastic composite materials. The composite panels were fabricated using vacuum assisted resin transfer moulding (VARTM) method. A full factorial design of experiments was use as an initial step to screen the significance of the parameters on the defects using Analysis of Variance (ANOVA). If the curvature of the collected data shows significant, Response Surface Methodology (RSM) is then applied for obtaining a quadratic modelling equation that has more reliable in expressing the optimization. Thus, the objective of this research is obtaining an optimum setting of milling parameters and modelling equations to minimize the surface roughness (Ra) and delamination factor (Fd) of milled kenaf reinforced plastic composite materials. The spindle speed and feed rate contributed the most in affecting the surface roughness and the delamination factor of the kenaf composite materials.

  8. Effect of Fiber Layers on the Fracture Resistance of Fiber Reinforced Composite Bridges

    Directory of Open Access Journals (Sweden)

    A Fazel

    2011-08-01

    Full Text Available Introduction: The purpose of this in vitro study was to introduce the fiber reinforced composite bridges and evaluate the most suitable site and position for placement of fibers in order to get maximum strength. Methods: The study included 20 second premolars and 20 second molars selected for fabricating twenty fiber reinforced composite bridges. Twenty specimens were selected for one fiber layer and the remaining teeth for two fiber layers. In the first group, fibers were placed in the inferior third and in the second group, fibers were placed in both the middle and inferior third region. After tooth preparation, the restorations were fabricated, thermocycled and then loaded with universal testing machine in the middle of the pontics with crosshead speed of 1mm/min. Data was analyzed by Kolmogorov-Smirnov test, Independent sample t test and Kaplan-Meier test. Mode of failure was evaluated using stereomicroscope. Results: Mean fracture resistance for the first and second groups was 1416±467N and 1349±397N, respectively. No significant differences were observed between the groups (P>0.05.In the first group, 5 specimens had delamintation and 5 specimens had detachment between fibers and resin composite. In the second group, there were 4 and 6 delaminations and detachments, respectively. There was no fracture within the fiber. Conclusion: In the fiber reinforced fixed partial dentures, fibers reinforce the tensile side of the connectors but placement of additional fibers at other sites does not increase the fracture resistance of the restoration.

  9. Genetic determinants of heat resistance in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Ryan eMercer

    2015-09-01

    Full Text Available Escherichia coli AW1.7 is a heat resistant food isolate and the occurrence of pathogenic strains with comparable heat resistance may pose a risk to food safety. To identify the genetic determinants of heat resistance, 29 strains of E. coli that differed in their of heat resistance were analyzed by comparative genomics. Strains were classified as highly heat resistant strains, exhibiting a D60-value of more than 6 min; moderately heat resistant strains, exhibiting a D60-value of more than 1 min; or as heat sensitive. A ~14 kb genomic island containing 16 predicted open reading frames encoding putative heat shock proteins and proteases was identified only in highly heat resistant strains. The genomic island was termed the locus of heat resistance (LHR. This putative operon is flanked by mobile elements and possesses >99% sequence identity to genomic islands contributing to heat resistance in Cronobacter sakazakii and Klebsiella pneumoniae. An additional 41 LHR sequences with >87% sequence identity were identified in 11 different species of β- and γ-proteobacteria. Cloning of the full length LHR conferred high heat resistance to the heat sensitive E. coli AW1.7ΔpHR1 and DH5α. The presence of the LHR correlates perfectly to heat resistance in several species of Enterobacteriaceae and occurs at a frequency of 2% of all E. coli genomes, including pathogenic strains. This study suggests the LHR has been laterally exchanged among the β- and γ-proteobacteria and is a reliable indicator of high heat resistance in E. coli.

  10. Reliable computer systems.

    Science.gov (United States)

    Wear, L L; Pinkert, J R

    1993-11-01

    In this article, we looked at some decisions that apply to the design of reliable computer systems. We began with a discussion of several terms such as testability, then described some systems that call for highly reliable hardware and software. The article concluded with a discussion of methods that can be used to achieve higher reliability in computer systems. Reliability and fault tolerance in computers probably will continue to grow in importance. As more and more systems are computerized, people will want assurances about the reliability of these systems, and their ability to work properly even when sub-systems fail.

  11. Reliability improvement of wire bonds subjected to fatigue stresses.

    Science.gov (United States)

    Ravi, K. V.; Philofsky, E. M.

    1972-01-01

    The failure of wire bonds due to repeated flexure when semiconductor devices are operated in an on-off mode has been investigated. An accelerated fatigue testing apparatus was constructed and the major fatigue variables, aluminum alloy composition, and bonding mechanism, were tested. The data showed Al-1% Mg wires to exhibit superior fatigue characteristics compared to Al-1% Cu or Al-1% Si and ultrasonic bonding to be better than thermocompression bonding for fatigue resistance. Based on these results highly reliable devices were fabricated using Al-1% Mg wire with ultrasonic bonding which withstood 120,000 power cycles with no failures.

  12. 78 FR 41339 - Electric Reliability Organization Proposal To Retire Requirements in Reliability Standards

    Science.gov (United States)

    2013-07-10

    ...] Electric Reliability Organization Proposal To Retire Requirements in Reliability Standards AGENCY: Federal... Reliability Standards identified by the North American Electric Reliability Corporation (NERC), the Commission-certified Electric Reliability Organization. FOR FURTHER INFORMATION CONTACT: Kevin Ryan (Legal Information...

  13. 76 FR 58101 - Electric Reliability Organization Interpretation of Transmission Operations Reliability Standard

    Science.gov (United States)

    2011-09-20

    ....C. Cir. 2009). \\4\\ Mandatory Reliability Standards for the Bulk-Power System, Order No. 693, FERC... for maintaining real and reactive power balance. \\14\\ Electric Reliability Organization Interpretation...; Order No. 753] Electric Reliability Organization Interpretation of Transmission Operations Reliability...

  14. Interlaminar Toughening of Fiber Reinforced Polymers

    Science.gov (United States)

    Bian, Dakai

    Modification in the resin-rich region between plies, also known as the interlaminar region, was investigated to increase the toughness of laminate composites structures. To achieve suitable modifications, the complexities of the physical and chemical processes during the resin curing procedure must be studied. This includes analyses of the interactions among the co-dependent microstructure, process parameters, and material responses. This dissertation seeks to investigate these interactions via a series of experimental and numerical analyses of the geometric- and temperature-based effects on locally interleaving toughening methods and further interlaminar synergistic toughening without interleaf. Two major weaknesses in composite materials are the brittle resin-rich interlaminar region which forms between the fiber plies after resin infusion, and the ply dropoff region which introduces stress concentration under loads. To address these weaknesses and increase the delamination resistance of the composite specimens, a dual bonding process was explored to alleviate the dropoff effect and toughen the interlaminar region. Hot melt bonding was investigated by applying clamping pressure to ductile thermoplastic interleaf and fiber fabric at an elevated temperature, while diffusion bonding between thermoplastic interleaf and thermoset resin is performed during the resin infusion. This method increased the fracture energy level and thus delamination resistance in the interlaminar region because of deep interleaf penetration into fiber bundles which helped confining crack propagation in the toughened area. The diffusion and precipitation between thermosets and thermoplastics also improved the delamination resistance by forming a semi-interpenetration networks. This phenomenon was investigated in concoctions of low-concentration polystyrene additive modified epoxy system, which facilitates diffusion and precipitation without increasing the viscosity of the system

  15. Radioactive resistance of memory elements

    International Nuclear Information System (INIS)

    Loncar, B.; Stankovic, S.; Novakovic, D.; Osmokrovic, P.

    1998-01-01

    In this paper, the results of semiconductor memories radioactive resistance examination (EPROM and EEPROM) are presented. Performance of semiconductor memories is most important, when working under high risk condition where there is an influence of radiation. This research is particularly interesting for specific applications in military industry and space technology. Therefore, the analysis of the degradation mechanism of these components as well as the possibilities to increase their radiation resistivity have been considered by many authors. The aim of this work is the examination of the reliability of EPROM and EEPROM characteristics under radiation. Total dose results are presented for the JL 27C512D EPROM and ST 24C02 EEPROM. There is evidence that EPROM are more sensitive to y radiation than EEPROM. The results obtained are analyzed theoretically via the interaction of gamma radiation with oxide layer. (authors)

  16. 76 FR 42534 - Mandatory Reliability Standards for Interconnection Reliability Operating Limits; System...

    Science.gov (United States)

    2011-07-19

    ... Reliability Operating Limits; System Restoration Reliability Standards AGENCY: Federal Energy Regulatory... data necessary to analyze and monitor Interconnection Reliability Operating Limits (IROL) within its... Interconnection Reliability Operating Limits, Order No. 748, 134 FERC ] 61,213 (2011). \\2\\ The term ``Wide-Area...

  17. Reliability of Maximal Strength Testing in Novice Weightlifters

    Science.gov (United States)

    Loehr, James A.; Lee, Stuart M. C.; Feiveson, Alan H.; Ploutz-Snyder, Lori L.

    2009-01-01

    ICC of greater than or equal to 0.90. Future resistive exercise studies should consider the reliability of specific measures to ensure that changes in strength with training are attributable to training and not learning effects associated with 1RM testing.

  18. Bayesian inversion from sabine absorption coefficients to flow resistivity values for porous absorbers

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2015-01-01

    to determine the flow resistivity of a porous material from the Sabine absorption coefficient was investigated through a reliable model. The model for the flow resistivity estimation is based on an equivalent fluid model, i.e., Miki’s model, together with the most advanced model that accounts for edge...... diffraction, named Thomasson’s finite size correction. As input data, a set of the Sabine absorption coefficients in a recent absorption round robin test in 13 European chambers was used. Finally, the flow resistivity of the test specimen is characterized via the Bayesian framework, together...

  19. Acetate-intercalated Ni–In layered double hydroxides with low infrared emissivity: Synthesis, delamination and restacked to form the multilayer films

    International Nuclear Information System (INIS)

    Wang, Yongjuan; Zhou, Yuming; Zhang, Tao; He, Man; Bu, Xiaohai; Yang, Xiaoming

    2014-01-01

    The low-emissive membrane materials have potential applications in infrared detecting technologies. Herein, we report a novel LDHs film with low infrared emissivity, which was based on the deposition of the exfoliated LDH nanosheets. The monodispersed hexagonal plate-like particles of Ni–In–CO 3 2− LDHs were prepared by coprecipitation method with hydrothermal treatment under optimized conditions. In order to exfoliate the LDHs into nanosheets, acetate-intercalated Ni–In LDHs were prepared by anion-exchange of Ni–In–CO 3 2− LDHs. The as-prepared acetate-intercalated LDHs exhibited excellent delaminating behavior in water and unilamellar nanosheets were easily obtained. The resulting positive-charged nanosheets were assembled onto quartz substrates to produce the multilayer films. The infrared emissivity values of all the samples were characterized. It was found that the incorporation of Ni 2+ and In 3+ in the host layer significantly reduced the infrared emissivity value. Moreover, the value was further reduced by the fabrication of multilayer ultrathin films, which can be ascribed to the dense orderly structure and smooth surface morphology.

  20. 76 FR 66055 - North American Electric Reliability Corporation; Order Approving Interpretation of Reliability...

    Science.gov (United States)

    2011-10-25

    ...\\ Mandatory Reliability Standards for the Bulk-Power System, Order No. 693, FERC Stats. & Regs. ] 31,242... materially affected'' by Bulk-Power System reliability may request an interpretation of a Reliability... Electric Reliability Corporation; Order Approving Interpretation of Reliability Standard; Before...

  1. Influence factors and temperature reliability of ohmic contact on AlGaN/GaN HEMTs

    Directory of Open Access Journals (Sweden)

    Liang Song

    2018-03-01

    Full Text Available In this paper, we have studied the performance of Ti/Al/Ni/Au ohmic contact with different Al and Au thicknesses and pretreatments. The temperature dependence of contact resistances (Rc was investigated and it shows that there are different optimal annealing temperatures with different metal thicknesses and pretreatments. The optimal annealing temperature is affected by Al and Au thickness and AlGaN thickness. The etched AlGaN barrier is useful to achieve good ohmic contact (0.24 Ω·mm with a low annealing temperature. Only the contact resistances of the samples with 130 nm Al layer kept stable and the contact resistances of the samples with 100nm and 160 nm Al layers increased with the measurement temperatures. The contact resistances showed a similar increase and then keep stable trend for all the samples in the long-term 400 °C aging process. The ohmic metal of 20/130/50/50 nm Ti/Al/Ni/Au with ICP etching is the superior candidate considering the contact resistance and reliability.

  2. Theoretical study of fuel element reliability in the BRIG-300 fast reactor

    International Nuclear Information System (INIS)

    Kulikov, I.S.; Nesterenko, V.B.; Tverkovkin, B.E.

    1983-01-01

    The theoretical results on studies of the reliability of cermet symmetrically heated fuel elements under conditions of the BRIG-300 fast gas cooled reactor are presented. The investigations have been conducted at the Nuclear Power Engineering Institute of the Byelorussian Academy of Sciences. Two variants of the fuel elements are considered :the fuel element with the gas gap between fuel and can and the fuel element with tight contact between cermet fuel and can. The estimated data on can resistance, swelling of the fuel rods and cans, strains and stresses in cans, change of the gap and its thermal coductivity during the reactor operation are obtained. The results of the analysis show that cermet fuel has sufficient reliability upon oparational conditions of the reactor with dissociating gas coolant in a steady-state regime

  3. Direct detection of Mycobacterium tuberculosis and drug resistance in respiratory specimen using Abbott Realtime MTB detection and RIF/INH resistance assay.

    Science.gov (United States)

    Tam, Kingsley King-Gee; Leung, Kenneth Siu-Sing; To, Sabrina Wai-Chi; Siu, Gilman Kit-Hang; Lau, Terrence Chi-Kong; Shek, Victor Chi-Man; Tse, Cindy Wing-Sze; Wong, Samson Sai-Yin; Ho, Pak-Leung; Yam, Wing-Cheong

    2017-10-01

    Abbott RealTime MTB (Abbott-RT) in conjunction with Abbott RealTime MTB RIF/INH Resistance (Abbott-RIF/INH) is a new, high-throughput automated nucleic acid amplification platform (Abbott-MDR) for detection of Mycobacterium tuberculosis complex (MTBC) and the genotypic markers for rifampicin (RIF) and isoniazid (INH) resistance directly from respiratory specimens. This prospective study evaluated the diagnostic performance of this new platform for MTBC and multidrug-resistant tuberculosis (MDR-TB) using 610 sputum specimens in a tuberculosis high-burden setting. Using conventional culture results and clinical background as reference standards, Abbott-RT exhibited an overall sensitivity and specificity of 95.2% and 99.8%, respectively. Genotypic RIF/INH resistance of 178 "MTB detected" specimens was subsequently analyzed by Abbott-RIF/INH. Compared to phenotypic drug susceptibility test results, Abbott-RIF/INH detected resistance genotypic markers in 84.6% MDR-TB, 80% mono-RIF-resistant and 66.7% mono-INH-resistant specimens. Two of the RIF-resistant specimens carried a novel single, nonsense mutation at rpoB Q513 and in silico simulation demonstrated that the truncated RpoB protein failed to bind with other subunits for transcription. Overall, Abbott-MDR platform provided high throughput and reliable diagnosis of MDR-TB within a TB high-burden region. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Inverse Reliability Task: Artificial Neural Networks and Reliability-Based Optimization Approaches

    OpenAIRE

    Lehký , David; Slowik , Ondřej; Novák , Drahomír

    2014-01-01

    Part 7: Genetic Algorithms; International audience; The paper presents two alternative approaches to solve inverse reliability task – to determine the design parameters to achieve desired target reliabilities. The first approach is based on utilization of artificial neural networks and small-sample simulation Latin hypercube sampling. The second approach considers inverse reliability task as reliability-based optimization task using double-loop method and also small-sample simulation. Efficie...

  5. Mechanical Properties for Reliability Analysis of Structures in Glassy Carbon

    CERN Document Server

    Garion, Cédric

    2014-01-01

    Despite its good physical properties, the glassy carbon material is not widely used, especially for structural applications. Nevertheless, its transparency to particles and temperature resistance are interesting properties for the applications to vacuum chambers and components in high energy physics. For example, it has been proposed for fast shutter valve in particle accelerator [1] [2]. The mechanical properties have to be carefully determined to assess the reliability of structures in such a material. In this paper, mechanical tests have been carried out to determine the elastic parameters, the strength and toughness on commercial grades. A statistical approach, based on the Weibull’s distribution, is used to characterize the material both in tension and compression. The results are compared to the literature and the difference of properties for these two loading cases is shown. Based on a Finite Element analysis, a statistical approach is applied to define the reliability of a structural component in gl...

  6. 76 FR 23801 - North American Electric Reliability Corporation; Order Approving Reliability Standard

    Science.gov (United States)

    2011-04-28

    ... have an operating plan and facilities for backup functionality to ensure Bulk-Power System reliability... entity's primary control center on the reliability of the Bulk-Power System. \\1\\ Mandatory Reliability... potential impact of a violation of the Requirement on the reliability of the Bulk-Power System. The...

  7. Screening for anthracnose disease resistance in strawberry using a detached leaf assay

    Science.gov (United States)

    Inoculation of detached strawberry leaves with Colletotrichum species may provide a rapid, non-destructive method of identifying anthracnose resistant germplasm. The reliability and validity of assessing disease severity is critical to disease management decisions. We inoculated detached strawberr...

  8. Suncor maintenance and reliability

    Energy Technology Data Exchange (ETDEWEB)

    Little, S. [Suncor Energy, Calgary, AB (Canada)

    2006-07-01

    Fleet maintenance and reliability at Suncor Energy was discussed in this presentation, with reference to Suncor Energy's primary and support equipment fleets. This paper also discussed Suncor Energy's maintenance and reliability standard involving people, processes and technology. An organizational maturity chart that graphed organizational learning against organizational performance was illustrated. The presentation also reviewed the maintenance and reliability framework; maintenance reliability model; the process overview of the maintenance and reliability standard; a process flow chart of maintenance strategies and programs; and an asset reliability improvement process flow chart. An example of an improvement initiative was included, with reference to a shovel reliability review; a dipper trip reliability investigation; bucket related failures by type and frequency; root cause analysis of the reliability process; and additional actions taken. Last, the presentation provided a graph of the results of the improvement initiative and presented the key lessons learned. tabs., figs.

  9. Fourier-based magnetic induction tomography for mapping resistivity

    International Nuclear Information System (INIS)

    Puwal, Steffan; Roth, Bradley J.

    2011-01-01

    Magnetic induction tomography is used as an experimental tool for mapping the passive electromagnetic properties of conductors, with the potential for imaging biological tissues. Our numerical approach to solving the inverse problem is to obtain a Fourier expansion of the resistivity and the stream functions of the magnetic fields and eddy current density. Thus, we are able to solve the inverse problem of determining the resistivity from the applied and measured magnetic fields for a two-dimensional conducting plane. When we add noise to the measured magnetic field, we find the fidelity of the measured to the true resistivity is quite robust for increasing levels of noise and increasing distances of the applied and measured field coils from the conducting plane, when properly filtered. We conclude that Fourier methods provide a reliable alternative for solving the inverse problem.

  10. Reliability and maintainability assessment factors for reliable fault-tolerant systems

    Science.gov (United States)

    Bavuso, S. J.

    1984-01-01

    A long term goal of the NASA Langley Research Center is the development of a reliability assessment methodology of sufficient power to enable the credible comparison of the stochastic attributes of one ultrareliable system design against others. This methodology, developed over a 10 year period, is a combined analytic and simulative technique. An analytic component is the Computer Aided Reliability Estimation capability, third generation, or simply CARE III. A simulative component is the Gate Logic Software Simulator capability, or GLOSS. The numerous factors that potentially have a degrading effect on system reliability and the ways in which these factors that are peculiar to highly reliable fault tolerant systems are accounted for in credible reliability assessments. Also presented are the modeling difficulties that result from their inclusion and the ways in which CARE III and GLOSS mitigate the intractability of the heretofore unworkable mathematics.

  11. Structural reliability methods: Code development status

    Science.gov (United States)

    Millwater, Harry R.; Thacker, Ben H.; Wu, Y.-T.; Cruse, T. A.

    1991-05-01

    The Probabilistic Structures Analysis Method (PSAM) program integrates state of the art probabilistic algorithms with structural analysis methods in order to quantify the behavior of Space Shuttle Main Engine structures subject to uncertain loadings, boundary conditions, material parameters, and geometric conditions. An advanced, efficient probabilistic structural analysis software program, NESSUS (Numerical Evaluation of Stochastic Structures Under Stress) was developed as a deliverable. NESSUS contains a number of integrated software components to perform probabilistic analysis of complex structures. A nonlinear finite element module NESSUS/FEM is used to model the structure and obtain structural sensitivities. Some of the capabilities of NESSUS/FEM are shown. A Fast Probability Integration module NESSUS/FPI estimates the probability given the structural sensitivities. A driver module, PFEM, couples the FEM and FPI. NESSUS, version 5.0, addresses component reliability, resistance, and risk.

  12. Reliability Engineering

    CERN Document Server

    Lazzaroni, Massimo

    2012-01-01

    This book gives a practical guide for designers and users in Information and Communication Technology context. In particular, in the first Section, the definition of the fundamental terms according to the international standards are given. Then, some theoretical concepts and reliability models are presented in Chapters 2 and 3: the aim is to evaluate performance for components and systems and reliability growth. Chapter 4, by introducing the laboratory tests, puts in evidence the reliability concept from the experimental point of view. In ICT context, the failure rate for a given system can be

  13. Reliability training

    Science.gov (United States)

    Lalli, Vincent R. (Editor); Malec, Henry A. (Editor); Dillard, Richard B.; Wong, Kam L.; Barber, Frank J.; Barina, Frank J.

    1992-01-01

    Discussed here is failure physics, the study of how products, hardware, software, and systems fail and what can be done about it. The intent is to impart useful information, to extend the limits of production capability, and to assist in achieving low cost reliable products. A review of reliability for the years 1940 to 2000 is given. Next, a review of mathematics is given as well as a description of what elements contribute to product failures. Basic reliability theory and the disciplines that allow us to control and eliminate failures are elucidated.

  14. Direct observations of surface water-groundwater interaction using electrical resistivity tomography

    NARCIS (Netherlands)

    Noell, Ursula; Wießner, Claudia; Ganz, Christina; Westhoff, Martijn

    2011-01-01

    Electrical resistivity tomography is a helpful tool to observe the infiltration process in and through the soil. Array 3-D measurements and 3-D inversion schemes are required for reliable interpretation of heterogeneous subsurface structures. Smoothing of the inversion can be minimized by using

  15. On reliability and maintenance modelling of ageing equipment in electric power systems

    International Nuclear Information System (INIS)

    Lindquist, Tommie

    2008-04-01

    Maintenance optimisation is essential to achieve cost-efficiency, availability and reliability of supply in electric power systems. The process of maintenance optimisation requires information about the costs of preventive and corrective maintenance, as well as the costs of failures borne by both electricity suppliers and customers. To calculate expected costs, information is needed about equipment reliability characteristics and the way in which maintenance affects equipment reliability. The aim of this Ph.D. work has been to develop equipment reliability models taking the effect of maintenance into account. The research has focussed on the interrelated areas of condition estimation, reliability modelling and maintenance modelling, which have been investigated in a number of case studies. In the area of condition estimation two methods to quantitatively estimate the condition of disconnector contacts have been developed, which utilise results from infrared thermography inspections and contact resistance measurements. The accuracy of these methods were investigated in two case studies. Reliability models have been developed and implemented for SF6 circuit-breakers, disconnector contacts and XLPE cables in three separate case studies. These models were formulated using both empirical and physical modelling approaches. To improve confidence in such models a Bayesian statistical method incorporating information from the equipment design process was also developed. This method was illustrated in a case study of SF6 circuit-breaker operating rods. Methods for quantifying the effect of maintenance on equipment condition and reliability have been investigated in case studies on disconnector contacts and SF6 circuit-breakers. The input required by these methods are condition measurements and historical failure and maintenance data, respectively. This research has demonstrated that the effect of maintenance on power system equipment may be quantified using available data

  16. Preparation of methodology for reliability analysis of selected digital segments of the instrumentation and control systems of NPPs. Pt. 1

    International Nuclear Information System (INIS)

    Hustak, S.; Patrik, M.; Babic, P.

    2000-12-01

    The report is structured as follows: (i) Introduction; (ii) Important notions relating to the safety and dependability of software systems for nuclear power plants (selected notions from IAEA Technical Report No. 397; safety aspects of software application; reliability/dependability aspects of digital systems); (iii) Peculiarities of digital systems and ways to a dependable performance of the required function (failures in the system and principles of defence against them; ensuring resistance of digital systems against failures at various hardware and software levels); (iv) The issue of analytical procedures to assess the safety and reliability of safety-related digital systems (safety and reliability assessment at an early stage of the project; general framework of reliability analysis of complex systems; choice of an appropriate quantitative measure of software reliability); (v) Selected qualitative and quantitative information about the reliability of digital systems; the use of relations between the incidence of various types of faults); and (vi) Conclusions and recommendations. (P.A.)

  17. 76 FR 16240 - Mandatory Reliability Standards for Interconnection Reliability Operating Limits

    Science.gov (United States)

    2011-03-23

    ... identified by the Commission. \\5\\ Mandatory Reliability Standards for the Bulk-Power System, Order No. 693... reliability of the interconnection by ensuring that the bulk electric system is assessed during the operations... responsibility for SOLs. Further, Bulk-Power System reliability practices assign responsibilities for analyzing...

  18. Design for reliability: NASA reliability preferred practices for design and test

    Science.gov (United States)

    Lalli, Vincent R.

    1994-01-01

    This tutorial summarizes reliability experience from both NASA and industry and reflects engineering practices that support current and future civil space programs. These practices were collected from various NASA field centers and were reviewed by a committee of senior technical representatives from the participating centers (members are listed at the end). The material for this tutorial was taken from the publication issued by the NASA Reliability and Maintainability Steering Committee (NASA Reliability Preferred Practices for Design and Test. NASA TM-4322, 1991). Reliability must be an integral part of the systems engineering process. Although both disciplines must be weighed equally with other technical and programmatic demands, the application of sound reliability principles will be the key to the effectiveness and affordability of America's space program. Our space programs have shown that reliability efforts must focus on the design characteristics that affect the frequency of failure. Herein, we emphasize that these identified design characteristics must be controlled by applying conservative engineering principles.

  19. Prediction of safety critical software operational reliability from test reliability using testing environment factors

    International Nuclear Information System (INIS)

    Jung, Hoan Sung; Seong, Poong Hyun

    1999-01-01

    It has been a critical issue to predict the safety critical software reliability in nuclear engineering area. For many years, many researches have focused on the quantification of software reliability and there have been many models developed to quantify software reliability. Most software reliability models estimate the reliability with the failure data collected during the test assuming that the test environments well represent the operation profile. User's interest is however on the operational reliability rather than on the test reliability. The experiences show that the operational reliability is higher than the test reliability. With the assumption that the difference in reliability results from the change of environment, from testing to operation, testing environment factors comprising the aging factor and the coverage factor are developed in this paper and used to predict the ultimate operational reliability with the failure data in testing phase. It is by incorporating test environments applied beyond the operational profile into testing environment factors. The application results show that the proposed method can estimate the operational reliability accurately. (Author). 14 refs., 1 tab., 1 fig

  20. Power electronics reliability analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Mark A.; Atcitty, Stanley

    2009-12-01

    This report provides the DOE and industry with a general process for analyzing power electronics reliability. The analysis can help with understanding the main causes of failures, downtime, and cost and how to reduce them. One approach is to collect field maintenance data and use it directly to calculate reliability metrics related to each cause. Another approach is to model the functional structure of the equipment using a fault tree to derive system reliability from component reliability. Analysis of a fictitious device demonstrates the latter process. Optimization can use the resulting baseline model to decide how to improve reliability and/or lower costs. It is recommended that both electric utilities and equipment manufacturers make provisions to collect and share data in order to lay the groundwork for improving reliability into the future. Reliability analysis helps guide reliability improvements in hardware and software technology including condition monitoring and prognostics and health management.

  1. Pristine carbon nanotubes based resistive temperature sensor

    International Nuclear Information System (INIS)

    Alam, Md Bayazeed; Saini, Sudhir Kumar; Sharma, Daya Shankar; Agarwal, Pankaj B.

    2016-01-01

    A good sensor must be highly sensitive, faster in response, of low cost cum easily producible, and highly reliable. Incorporation of nano-dimensional particles/ wires makes conventional sensors more effective in terms of fulfilling the above requirements. For example, Carbon Nanotubes (CNTs) are promising sensing element because of its large aspect ratio, unique electronic and thermal properties. In addition to their use for widely reported chemical sensing, it has also been explored for temperature sensing. This paper presents the fabrication of CNTs based temperature sensor, prepared on silicon substrate using low cost spray coating method, which is reliable and reproducible method to prepare uniform CNTs thin films on any substrate. Besides this, simple and inexpensive method of preparation of dispersion of single walled CNTs (SWNTs) in 1,2 dichlorobenzene by using probe type ultrasonicator for debundling the CNTs for improving sensor response were used. The electrical contacts over the dispersed SWNTs were taken using silver paste electrodes. Fabricated sensors clearly show immediate change in resistance as a response to change in temperature of SWNTs. The measured sensitivity (change in resistance with temperature) of the sensor was found ∼ 0.29%/°C in the 25°C to 60°C temperature range.

  2. Pristine carbon nanotubes based resistive temperature sensor

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Md Bayazeed, E-mail: bayazeed786@gmail.com [CSIR-Central Electronics Engineering Research Institute (CEERI, Pilani, India) (India); Jamia Millia Islamia (New Delhi, India) (India); Saini, Sudhir Kumar, E-mail: sudhirsaini1310@gmail.com [CSIR-Central Electronics Engineering Research Institute (CEERI, Pilani, India) (India); Sharma, Daya Shankar, E-mail: dssharmanit15@gmail.com [CSIR-Central Electronics Engineering Research Institute (CEERI, Pilani, India) (India); Maulana Azad National Institute of Technology (MANIT, Bhopal, India) (India); Agarwal, Pankaj B., E-mail: agarwalbpankj@gmail.com [CSIR-Central Electronics Engineering Research Institute (CEERI, Pilani, India) (India); Academy for Scientific and Innovative Research (AcSIR, Delhi, India) (India)

    2016-04-13

    A good sensor must be highly sensitive, faster in response, of low cost cum easily producible, and highly reliable. Incorporation of nano-dimensional particles/ wires makes conventional sensors more effective in terms of fulfilling the above requirements. For example, Carbon Nanotubes (CNTs) are promising sensing element because of its large aspect ratio, unique electronic and thermal properties. In addition to their use for widely reported chemical sensing, it has also been explored for temperature sensing. This paper presents the fabrication of CNTs based temperature sensor, prepared on silicon substrate using low cost spray coating method, which is reliable and reproducible method to prepare uniform CNTs thin films on any substrate. Besides this, simple and inexpensive method of preparation of dispersion of single walled CNTs (SWNTs) in 1,2 dichlorobenzene by using probe type ultrasonicator for debundling the CNTs for improving sensor response were used. The electrical contacts over the dispersed SWNTs were taken using silver paste electrodes. Fabricated sensors clearly show immediate change in resistance as a response to change in temperature of SWNTs. The measured sensitivity (change in resistance with temperature) of the sensor was found ∼ 0.29%/°C in the 25°C to 60°C temperature range.

  3. SALIVARY CORTISOL RESPONSES AND PERCEIVED EXERTION DURING HIGH INTENSITY AND LOW INTENSITY BOUTS OF RESISTANCE EXERCISE

    Directory of Open Access Journals (Sweden)

    Alison D. Egan

    2004-03-01

    Full Text Available The purpose of this study was to measure the salivary cortisol response to different intensities of resistance exercise. In addition, we wanted to determine the reliability of the session rating of perceived exertion (RPE scale to monitor resistance exercise intensity. Subjects (8 men, 9 women completed 2 trials of acute resistance training bouts in a counterbalanced design. The high intensity resistance exercise protocol consisted of six, ten-repetition sets using 75% of one repetition maximum (RM on a Smith machine squat and bench press exercise (12 sets total. The low intensity resistance exercise protocol consisted of three, ten-repetition sets at 30% of 1RM of the same exercises as the high intensity protocol. Both exercise bouts were performed with 2 minutes of rest between each exercise and sessions were repeated to test reliability of the measures. The order of the exercise bouts was randomized with least 72 hours between each session. Saliva samples were obtained immediately before, immediately after and 30 mins following each resistance exercise bout. RPE measures were obtained using Borg's CR-10 scale following each set. Also, the session RPE for the entire exercise session was obtained 30 minutes following completion of the session. There was a significant 97% increase in the level of salivary cortisol immediately following the high intensity exercise session (P<0.05. There was also a significant difference in salivary cortisol of 145% between the low intensity and high intensity exercise session immediately post-exercise (P<0.05. The low intensity exercise did not result in any significant changes in cortisol levels. There was also a significant difference between the session RPE values for the different intensity levels (high intensity 7.1 vs. low intensity 1.9 (P<0.05. The intraclass correlation coefficient for the session RPE measure was 0.95. It was concluded that the session RPE method is a valid and reliable method of

  4. 76 FR 73608 - Reliability Technical Conference, North American Electric Reliability Corporation, Public Service...

    Science.gov (United States)

    2011-11-29

    ... or municipal authority play in forming your bulk power system reliability plans? b. Do you support..., North American Electric Reliability Corporation (NERC) Nick Akins, CEO of American Electric Power (AEP..., EL11-62-000] Reliability Technical Conference, North American Electric Reliability Corporation, Public...

  5. Identification of different geologic units using fuzzy constrained resistivity tomography

    Science.gov (United States)

    Singh, Anand; Sharma, S. P.

    2018-01-01

    Different geophysical inversion strategies are utilized as a component of an interpretation process that tries to separate geologic units based on the resistivity distribution. In the present study, we present the results of separating different geologic units using fuzzy constrained resistivity tomography. This was accomplished using fuzzy c means, a clustering procedure to improve the 2D resistivity image and geologic separation within the iterative minimization through inversion. First, we developed a Matlab-based inversion technique to obtain a reliable resistivity image using different geophysical data sets (electrical resistivity and electromagnetic data). Following this, the recovered resistivity model was converted into a fuzzy constrained resistivity model by assigning the highest probability value of each model cell to the cluster utilizing fuzzy c means clustering procedure during the iterative process. The efficacy of the algorithm is demonstrated using three synthetic plane wave electromagnetic data sets and one electrical resistivity field dataset. The presented approach shows improvement on the conventional inversion approach to differentiate between different geologic units if the correct number of geologic units will be identified. Further, fuzzy constrained resistivity tomography was performed to examine the augmentation of uranium mineralization in the Beldih open cast mine as a case study. We also compared geologic units identified by fuzzy constrained resistivity tomography with geologic units interpreted from the borehole information.

  6. Assessing reliability and useful life of containers for disposal of irradiated fuel waste

    International Nuclear Information System (INIS)

    Doubt, G.

    1984-06-01

    Metal containers for fuel waste isolation are to be designed to last at least 500 years to provide a redundant barrier during the decay period of the high activity components of the waste. To meet the long-life requirement, containers must have a very low failure rate during the design mission, a low incidence of 'juvenile failures' due to undetected defects, and resistance to progressive deterioration from environmental processes. This paper summarizes studies to determine: (1) precedent for low failure rates and relevance to container longevity; (b) the likelihood of initial defects perforating the container before or shortly after emplacement, and estimates of material defect distribution; (c) the utility of reliability analysis techniques for estimating reliability and life of fuel waste containers; (d) other approaches to estimating container longevity and failure versus time distribution

  7. Improved Reliability of SiC Pressure Sensors for Long Term High Temperature Applications

    Science.gov (United States)

    Okojie, R. S.; Nguyen, V.; Savrun, E.; Lukco, D.

    2011-01-01

    We report advancement in the reliability of silicon carbide pressure sensors operating at 600 C for extended periods. The large temporal drifts in zero pressure offset voltage at 600 C observed previously were significantly suppressed to allow improved reliable operation. This improvement was the result of further enhancement of the electrical and mechanical integrity of the bondpad/contact metallization, and the introduction of studded bump bonding on the pad. The stud bump contact promoted strong adhesion between the Au bond pad and the Au die-attach. The changes in the zero offset voltage and bridge resistance over time at temperature were explained by the microstructure and phase changes within the contact metallization, that were analyzed with Auger electron spectroscopy (AES) and field emission scanning electron microscopy (FE-SEM).

  8. Reliability-Based Design of Wind Turbine Foundations

    DEFF Research Database (Denmark)

    Firouzianbandpey, Sarah

    reliable, affordable, clean and renewable energy. Wind turbines have gained popularity among other renewable energy generators by having both technically and economically efficient features and by offering competitive production prices compared to other renewable energy sources. Therefore, it is a key...... shorter spatial correlation lengths in the vertical direction as a result of the depositional process. The normalized cone resistance is a better estimator of spatial trends compared to the normalized friction ratio. In geotechnical engineering analysis and design, practitioners ideally would like to know...... the soil properties at many locations, but achieving this goal can be unrealistic and expensive. Therefore, developing ways to determine these parameters using statistical approaches is of great interest. This research employs a random field model to deal with uncertainty in soil properties due to spatial...

  9. The Accelerator Reliability Forum

    CERN Document Server

    Lüdeke, Andreas; Giachino, R

    2014-01-01

    A high reliability is a very important goal for most particle accelerators. The biennial Accelerator Reliability Workshop covers topics related to the design and operation of particle accelerators with a high reliability. In order to optimize the over-all reliability of an accelerator one needs to gather information on the reliability of many different subsystems. While a biennial workshop can serve as a platform for the exchange of such information, the authors aimed to provide a further channel to allow for a more timely communication: the Particle Accelerator Reliability Forum [1]. This contribution will describe the forum and advertise it’s usage in the community.

  10. Design reliability engineering

    International Nuclear Information System (INIS)

    Buden, D.; Hunt, R.N.M.

    1989-01-01

    Improved design techniques are needed to achieve high reliability at minimum cost. This is especially true of space systems where lifetimes of many years without maintenance are needed and severe mass limitations exist. Reliability must be designed into these systems from the start. Techniques are now being explored to structure a formal design process that will be more complete and less expensive. The intent is to integrate the best features of design, reliability analysis, and expert systems to design highly reliable systems to meet stressing needs. Taken into account are the large uncertainties that exist in materials, design models, and fabrication techniques. Expert systems are a convenient method to integrate into the design process a complete definition of all elements that should be considered and an opportunity to integrate the design process with reliability, safety, test engineering, maintenance and operator training. 1 fig

  11. Active Thermal Control for Reliability Improvement of MOS-gated Power Devices

    DEFF Research Database (Denmark)

    Soldati, Alessandro; Concari, Carlo; Dossena, Fabrizio

    2017-01-01

    reliability and lifetime. These figures can then be improved, which eases the adoption of electrification in markets, such as transportation, where they are still below target values. The proposed ATC method leaves electric load parameters untouched, while acting dynamically on gate parameters, namely voltage...... and resistance. A model-predictive control (MPC) strategy is used to determine the most suitable parameters to use. Simulations of the control scheme are presented first, to predict the potential benefits on temperature swing amplitude, and the consequent improvements in terms of device lifetime are inferred...

  12. Isothermal and dynamic oxidation behaviour of Mo-W doped carbon-based coating

    Science.gov (United States)

    Mandal, Paranjayee; Ehiasarian, Arutiun P.; Hovsepian, Papken Eh.

    2015-10-01

    The oxidation behaviour of Mo-W doped carbon-based coating (Mo-W-C) is investigated in elevated temperature (400-1000 °C). Strong metallurgical bond between Mo-W-C coating and substrate prevents any sort of delamination during heat-treatment. Isothermal oxidation tests show initial growth of metal oxides at 500 °C, however graphitic nature of the as-deposited coating is preserved. The oxidation progresses with further rise in temperature and the substrate is eventually exposed at 700 °C. The performance of Mo-W-C coating is compared with a state-of-the-art DLC(Cr/Cr-WC/W:C-H/a:C-H) coating, which shows preliminary oxidation at 400 °C and local delamination of the coating at 500 °C leading to substrate exposure. The graphitisation starts at 400 °C and the diamond-like structure is completely converted into the graphite-like structure at 500 °C. Dynamic oxidation behaviour of both the coatings is investigated using Thermo-gravimetric analysis carried out with a slow heating rate of 1 °C/min from ambient temperature to 1000 °C. Mo-W-C coating resists oxidation up to ˜800 °C whereas delamination of DLC(Cr/Cr-WC/W:C-H/a:C-H) coating is observed beyond ˜380 °C. In summary, Mo-W-C coating provides improved oxidation resistance at elevated temperature compared to DLC(Cr/Cr-WC/W:C-H/a:C-H) coating.

  13. A study of cross-bridge kelvin resistor structures for reliable measurement of low contact resistances

    NARCIS (Netherlands)

    Stavitski, N.; Klootwijk, J.H.; van Zeijl, H.W.; Kovalgin, Alexeij Y.; Wolters, Robertus A.M.

    2008-01-01

    The parasitic factors that strongly influence the measurement accuracy of Cross-Bridge Kelvin Resistor (CBKR) structures for low specific contact resistances (�?c) have been extensively discussed during last few decades and the minimum of the �?c value, which could be accurately extracted, was

  14. Uncertainty Analysis of Resistance Tests in Ata Nutku Ship Model Testing Laboratory of Istanbul Technical University

    Directory of Open Access Journals (Sweden)

    Cihad DELEN

    2015-12-01

    Full Text Available In this study, some systematical resistance tests, where were performed in Ata Nutku Ship Model Testing Laboratory of Istanbul Technical University (ITU, have been included in order to determine the uncertainties. Experiments which are conducted in the framework of mathematical and physical rules for the solution of engineering problems, measurements, calculations include uncertainty. To question the reliability of the obtained values, the existing uncertainties should be expressed as quantities. The uncertainty of a measurement system is not known if the results do not carry a universal value. On the other hand, resistance is one of the most important parameters that should be considered in the process of ship design. Ship resistance during the design phase of a ship cannot be determined precisely and reliably due to the uncertainty resources in determining the resistance value that are taken into account. This case may cause negative effects to provide the required specifications in the latter design steps. The uncertainty arising from the resistance test has been estimated and compared for a displacement type ship and high speed marine vehicles according to ITTC 2002 and ITTC 2014 regulations which are related to the uncertainty analysis methods. Also, the advantages and disadvantages of both ITTC uncertainty analysis methods have been discussed.

  15. Reliability of electronic systems

    International Nuclear Information System (INIS)

    Roca, Jose L.

    2001-01-01

    Reliability techniques have been developed subsequently as a need of the diverse engineering disciplines, nevertheless they are not few those that think they have been work a lot on reliability before the same word was used in the current context. Military, space and nuclear industries were the first ones that have been involved in this topic, however not only in these environments it is that it has been carried out this small great revolution in benefit of the increase of the reliability figures of the products of those industries, but rather it has extended to the whole industry. The fact of the massive production, characteristic of the current industries, drove four decades ago, to the fall of the reliability of its products, on one hand, because the massively itself and, for other, to the recently discovered and even not stabilized industrial techniques. Industry should be changed according to those two new requirements, creating products of medium complexity and assuring an enough reliability appropriated to production costs and controls. Reliability began to be integral part of the manufactured product. Facing this philosophy, the book describes reliability techniques applied to electronics systems and provides a coherent and rigorous framework for these diverse activities providing a unifying scientific basis for the entire subject. It consists of eight chapters plus a lot of statistical tables and an extensive annotated bibliography. Chapters embrace the following topics: 1- Introduction to Reliability; 2- Basic Mathematical Concepts; 3- Catastrophic Failure Models; 4-Parametric Failure Models; 5- Systems Reliability; 6- Reliability in Design and Project; 7- Reliability Tests; 8- Software Reliability. This book is in Spanish language and has a potentially diverse audience as a text book from academic to industrial courses. (author)

  16. Comparison of the cohesive and delamination fatigue properties of atomic-layer-deposited alumina and titania ultrathin protective coatings deposited at 200 °C

    Directory of Open Access Journals (Sweden)

    Farzad Sadeghi-Tohidi

    2014-01-01

    Full Text Available The fatigue properties of ultrathin protective coatings on silicon thin films were investigated. The cohesive and delamination fatigue properties of 22 nm-thick atomic-layered-deposited (ALD titania were characterized and compared to that of 25 nm-thick alumina. Both coatings were deposited at 200 °C. The fatigue rates are comparable at 30 °C, 50% relative humidity (RH while they are one order of magnitude larger for alumina compared to titania at 80 °C, 90% RH. The improved fatigue performance is believed to be related to the improved stability of the ALD titania coating with water compared to ALD alumina, which may in part be related to the fact that ALD titania is crystalline, while ALD alumina is amorphous. Static fatigue crack nucleation and propagation was not observed. The underlying fatigue mechanism is different from previously documented mechanisms, such as stress corrosion cracking, and appears to result from the presence of compressive stresses and a rough coating–substrate interface.

  17. A technique to study Meloidogyne arenaria resistance in Agrobacterium rhizogenes-transformed peanut

    Science.gov (United States)

    A reliable peanut root transformation system would be useful to study the functions of genes involved in root biology and disease resistance. The objective of this study was to establish an effective protocol to produce composite plants mediated by Agrobacterium rhizogenes transformation. More tha...

  18. Analysis and Application of Reliability

    International Nuclear Information System (INIS)

    Jeong, Hae Seong; Park, Dong Ho; Kim, Jae Ju

    1999-05-01

    This book tells of analysis and application of reliability, which includes definition, importance and historical background of reliability, function of reliability and failure rate, life distribution and assumption of reliability, reliability of unrepaired system, reliability of repairable system, sampling test of reliability, failure analysis like failure analysis by FEMA and FTA, and cases, accelerated life testing such as basic conception, acceleration and acceleration factor, and analysis of accelerated life testing data, maintenance policy about alternation and inspection.

  19. Improvement of mechanical reliability by patterned silver/Indium-Tin-Oxide structure for flexible electronic devices

    International Nuclear Information System (INIS)

    Baek, Kyunghyun; Jang, Kyungsoo; Lee, Youn-Jung; Ryu, Kyungyul; Choi, Woojin; Kim, Doyoung; Yi, Junsin

    2013-01-01

    We report the effect of silver (Ag)-buffer layer Indium-Tin-Oxide (ITO) film on a polyethylene terephthalate substrate on the electrical, optical and reliable properties for transparent–flexible displays. The electrical and optical characteristics of an ITO-only film and an Ag-layer-inserted ITO film are measured and compared to assess the applicability of the triple layered structure in flexible displays. The sheet resistance, the resistivity and the light transmittance of the ITO-only film were 400 Ω/sq, 1.33 × 10 −3 Ω-cm and 99.2%, while those of the ITO film inserted with a 10 nm thick Ag layer were 165 Ω/sq, 4.78 × 10 −4 Ω-cm and about 97%, respectively. To evaluate the mechanical reliability of the different ITO films, bending tests were carried out. After the dynamic bending test of 900 cycles, the sheet resistance of the ITO film inserted with the Ag layer changed from 154 Ω/sq to 475 Ω/sq, about a 3-time increase but that of the ITO-only film changed from 400 Ω/sq to 61,986 Ω/sq, about 150-time increase. When the radius is changed from 25 mm to 20 mm in the static bending test, the sheet resistance of the ITO-only film changed from 400 to 678.3 linearly whereas that of the Ag-layer inserted ITO film changed a little from 154.4 to 154.9. These results show that Ag-layer inserted ITO film had better mechanical characteristics than the ITO-only film. - Highlights: ► Transparent flexible electrode fabricated on glass substrate. ► Electrode fabricated using vertically-patterned design on glass substrate. ► Optimization of the vertical patterns ► Application of the vertically-patterned electrode in transparent–flexible electronics

  20. Effects of core-to-dentin thickness ratio on the biaxial flexural strength, reliability, and fracture mode of bilayered materials of zirconia core (Y-TZP) and veneer indirect composite resins.

    Science.gov (United States)

    Su, Naichuan; Liao, Yunmao; Zhang, Hai; Yue, Li; Lu, Xiaowen; Shen, Jiefei; Wang, Hang

    2017-01-01

    Indirect composite resins (ICR) are promising alternatives as veneering materials for zirconia frameworks. The effects of core-to-dentin thickness ratio (C/Dtr) on the mechanical property of bilayered veneer ICR/yttria-tetragonal zirconia polycrystalline (Y-TZP) core disks have not been previously studied. The purpose of this in vitro study was to assess the effects of C/Dtr on the biaxial flexural strength, reliability, and fracture mode of bilayered veneer ICR/ Y-TZP core disks. A total of 180 bilayered 0.6-mm-thick composite resin disks in core material and C/Dtr of 2:1, 1:1, and 1:2 were tested with either core material placed up or placed down for piston-on-3-ball biaxial flexural strength. The mean biaxial flexural strength, Weibull modulus, and fracture mode were measured to evaluate the variation trend of the biaxial flexural strength, reliability, and fracture mode of the bilayered disks with various C/Dtr. One-way analysis of variance (ANOVA) and chi-square tests were used to evaluate the variation tendency of fracture mode with the C/Dtr or material placed down during testing (α=.05). Light microscopy was used to identify the fracture mode. The mean biaxial flexural strength and reliability improved with the increase in C/Dtr when specimens were tested with the core material either up and down, and depended on the materials that were placed down during testing. The rates of delamination, Hertzian cone cracks, subcritical radial cracks, and number of fracture fragments partially depended on the C/Dtr and the materials that were placed down during testing. The biaxial flexural strength, reliability, and fracture mode in bilayered structures of Y-TZP core and veneer ICR depend on both the C/Dtr and the material that was placed down during testing. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  1. Reliability in automotive and mechanical engineering determination of component and system reliability

    CERN Document Server

    Bertsche, Bernd

    2008-01-01

    In the present contemporary climate of global competition in every branch of engineering and manufacture it has been shown from extensive customer surveys that above every other attribute, reliability stands as the most desired feature in a finished product. To survive this relentless fight for survival any organisation, which neglect the plea of attaining to excellence in reliability, will do so at a serious cost Reliability in Automotive and Mechanical Engineering draws together a wide spectrum of diverse and relevant applications and analyses on reliability engineering. This is distilled into this attractive and well documented volume and practising engineers are challenged with the formidable task of simultaneously improving reliability and reducing the costs and down-time due to maintenance. The volume brings together eleven chapters to highlight the importance of the interrelated reliability and maintenance disciplines. They represent the development trends and progress resulting in making this book ess...

  2. Washable and Reliable Textile Electrodes Embedded into Underwear Fabric for Electrocardiography (ECG) Monitoring

    OpenAIRE

    Amale Ankhili; Xuyuan Tao; Cédric Cochrane; David Coulon; Vladan Koncar

    2018-01-01

    A medical quality electrocardiogram (ECG) signal is necessary for permanent monitoring, and an accurate heart examination can be obtained from instrumented underwear only if it is equipped with high-quality, flexible, textile-based electrodes guaranteeing low contact resistance with the skin. The main objective of this article is to develop reliable and washable ECG monitoring underwear able to record and wirelessly send an ECG signal in real time to a smart phone and further to a cloud. The ...

  3. Assessment of reliability of CAD-CAM tooth-colored implant custom abutments.

    Science.gov (United States)

    Guilherme, Nuno Marques; Chung, Kwok-Hung; Flinn, Brian D; Zheng, Cheng; Raigrodski, Ariel J

    2016-08-01

    Information is lacking about the fatigue resistance of computer-aided design and computer-aided manufacturing (CAD-CAM) tooth-colored implant custom abutment materials. The purpose of this in vitro study was to investigate the reliability of different types of CAD-CAM tooth-colored implant custom abutments. Zirconia (Lava Plus), lithium disilicate (IPS e.max CAD), and resin-based composite (Lava Ultimate) abutments were fabricated using CAD-CAM technology and bonded to machined titanium-6 aluminum-4 vanadium (Ti-6Al-4V) alloy inserts for conical connection implants (NobelReplace Conical Connection RP 4.3×10 mm; Nobel Biocare). Three groups (n=19) were assessed: group ZR, CAD-CAM zirconia/Ti-6Al-4V bonded abutments; group RC, CAD-CAM resin-based composite/Ti-6Al-4V bonded abutments; and group LD, CAD-CAM lithium disilicate/Ti-6Al-4V bonded abutments. Fifty-seven implant abutments were secured to implants and embedded in autopolymerizing acrylic resin according to ISO standard 14801. Static failure load (n=5) and fatigue failure load (n=14) were tested. Weibull cumulative damage analysis was used to calculate step-stress reliability at 150-N and 200-N loads with 2-sided 90% confidence limits. Representative fractured specimens were examined using stereomicroscopy and scanning electron microscopy to observe fracture patterns. Weibull plots revealed β values of 2.59 for group ZR, 0.30 for group RC, and 0.58 for group LD, indicating a wear-out or cumulative fatigue pattern for group ZR and load as the failure accelerating factor for groups RC and LD. Fractographic observation disclosed that failures initiated in the interproximal area where the lingual tensile stresses meet the compressive facial stresses for the early failure specimens. Plastic deformation of titanium inserts with fracture was observed for zirconia abutments in fatigue resistance testing. Significantly higher reliability was found in group ZR, and no significant differences in reliability were

  4. Enhanced cyclic performance and lithium storage capacity of SnO2/graphene nanoporous electrodes with three-dimensionally delaminated flexible structure.

    Science.gov (United States)

    Paek, Seung-Min; Yoo, EunJoo; Honma, Itaru

    2009-01-01

    To fabricate nanoporous electrode materials with delaminated structure, the graphene nanosheets (GNS) in the ethylene glycol solution were reassembled in the presence of rutile SnO(2) nanoparticles. According to the TEM analysis, the graphene nanosheets are homogeneously distributed between the loosely packed SnO(2) nanoparticles in such a way that the nanoporous structure with a large amount of void spaces could be prepared. The obtained SnO(2)/GNS exhibits a reversible capacity of 810 mAh/g; furthermore, its cycling performance is drastically enhanced in comparison with that of the bare SnO(2) nanoparticle. After 30 cycles, the charge capacity of SnO(2)/GNS still remained 570 mAh/g, that is, about 70% retention of the reversible capacity, while the specific capacity of the bare SnO(2) nanoparticle on the first charge was 550 mAh/g, dropping rapidly to 60 mAh/g only after 15 cycles. The dimensional confinement of tin oxide nanoparticles by the surrounding GNS limits the volume expansion upon lithium insertion, and the developed pores between SnO(2) and GNS could be used as buffered spaces during charge/discharge, resulting in the superior cyclic performances.

  5. Techniques to maximize software reliability in radiation fields

    International Nuclear Information System (INIS)

    Eichhorn, G.; Piercey, R.B.

    1986-01-01

    Microprocessor system failures due to memory corruption by single event upsets (SEUs) and/or latch-up in RAM or ROM memory are common in environments where there is high radiation flux. Traditional methods to harden microcomputer systems against SEUs and memory latch-up have usually involved expensive large scale hardware redundancy. Such systems offer higher reliability, but they tend to be more complex and non-standard. At the Space Astronomy Laboratory the authors have developed general programming techniques for producing software which is resistant to such memory failures. These techniques, which may be applied to standard off-the-shelf hardware, as well as custom designs, include an implementation of Maximally Redundant Software (MRS) model, error detection algorithms and memory verification and management

  6. Effect of surfaces similarity on contact resistance of fractal rough surfaces under cyclic loading

    Science.gov (United States)

    Gao, Yuanwen; Liu, Limei; Ta, Wurui; Song, Jihua

    2018-03-01

    Although numerous studies have shown that contact resistance depends significantly on roughness and fractal dimension, it remains elusive how they affect contact resistance between rough surfaces. The interface similarity index is first proposed to describe the similarity of the contact surfaces, which gives a good indication of the actual contact area between surfaces. We reveal that the surfaces' similarity be an origin of contact resistance variation. The cyclic loading can increase the contact stiffness, and the contact stiffness increases with the increase of the interface similarity index. These findings explain the mechanism of surface roughness and fractal dimension on contact resistance, and also provide reference for the reliability design of the electrical connection.

  7. Microelectronics Reliability

    Science.gov (United States)

    2017-01-17

    inverters  connected in a chain. ................................................. 5  Figure 3  Typical graph showing frequency versus square root of...developing an experimental  reliability estimating methodology that could both illuminate the  lifetime  reliability of advanced devices,  circuits and...or  FIT of the device. In other words an accurate estimate of the device  lifetime  was found and thus the  reliability  that  can  be  conveniently

  8. A Built-In Self-Test Structure (BIST) for Resistive RAMs characterization: Application to bipolar OxRRAM

    Science.gov (United States)

    Aziza, H.; Bocquet, M.; Moreau, M.; Portal, J.-M.

    2015-01-01

    Resistive Random Access Memory (RRAM) is a form of nonvolatile storage that operates by changing the resistance of a specially formulated solid dielectric material [1]. Among RRAMs, oxide-based Resistive RAMs (so-called OxRRAMs) are promising candidates due their compatibility with CMOS processes and high ON/OFF resistance ratio. Common problems with OxRRAM are related to high variability in operating conditions and low yield. OxRRAM variability mainly impact ON/OFF resistance ratio. This ratio is a key parameter to determine the overall performance of an OxRRAM memory. In this context, the presented built-in structure allows collecting statistical data related to the OxRRAM memory array (ON/OFF resistance distributions) for reliability assessment of the technology.

  9. Human reliability analysis

    International Nuclear Information System (INIS)

    Dougherty, E.M.; Fragola, J.R.

    1988-01-01

    The authors present a treatment of human reliability analysis incorporating an introduction to probabilistic risk assessment for nuclear power generating stations. They treat the subject according to the framework established for general systems theory. Draws upon reliability analysis, psychology, human factors engineering, and statistics, integrating elements of these fields within a systems framework. Provides a history of human reliability analysis, and includes examples of the application of the systems approach

  10. Hawaii Electric System Reliability

    Energy Technology Data Exchange (ETDEWEB)

    Loose, Verne William [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Silva Monroy, Cesar Augusto [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2012-08-01

    This report addresses Hawaii electric system reliability issues; greater emphasis is placed on short-term reliability but resource adequacy is reviewed in reference to electric consumers’ views of reliability “worth” and the reserve capacity required to deliver that value. The report begins with a description of the Hawaii electric system to the extent permitted by publicly available data. Electrical engineering literature in the area of electric reliability is researched and briefly reviewed. North American Electric Reliability Corporation standards and measures for generation and transmission are reviewed and identified as to their appropriateness for various portions of the electric grid and for application in Hawaii. Analysis of frequency data supplied by the State of Hawaii Public Utilities Commission is presented together with comparison and contrast of performance of each of the systems for two years, 2010 and 2011. Literature tracing the development of reliability economics is reviewed and referenced. A method is explained for integrating system cost with outage cost to determine the optimal resource adequacy given customers’ views of the value contributed by reliable electric supply. The report concludes with findings and recommendations for reliability in the State of Hawaii.

  11. A new aspects for project of subsequent thermal resistance extension at old-timer timbering constructions of wood

    Directory of Open Access Journals (Sweden)

    Zdeňka Havířová

    2006-01-01

    Full Text Available To ensure the reliability of subsequent thermal resistance extension at old-timer timbering constructions of wood for the period of their supposed service life a more profound analysis of construction is necessary from the aspect of a global thermal/technical evaluation. Service life of these buildings is dependent on temperature and moisture conditions in layers of the building cladding where the wood framework is built in. Temperature/moisture conditions or the corresponding equilibrium moisture content (EMC of the construction show considerable effects on the functional reliability of the whole building from the viewpoint of mechanical resistance and stability, energy savings and thermal protection and hygiene, health and environment protection.

  12. Pocket Handbook on Reliability

    Science.gov (United States)

    1975-09-01

    exponencial distributions Weibull distribution, -xtimating reliability, confidence intervals, relia- bility growth, 0. P- curves, Bayesian analysis. 20 A S...introduction for those not familiar with reliability and a good refresher for those who are currently working in the area. LEWIS NERI, CHIEF...includes one or both of the following objectives: a) prediction of the current system reliability, b) projection on the system reliability for someI future

  13. Relationship between Vancomycin-Resistant Staphylococcus aureus, Vancomycin-Intermediate S. aureus, High Vancomycin MIC, and Outcome in Serious S. aureus Infections

    OpenAIRE

    Holmes, Natasha E.; Johnson, Paul D. R.; Howden, Benjamin P.

    2012-01-01

    Vancomycin has been used successfully for over 50 years for the treatment of Staphylococcus aureus infections, particularly those involving methicillin-resistant S. aureus. It has proven remarkably reliable, but its efficacy is now being questioned with the emergence of strains of S. aureus that display heteroresistance, intermediate resistance, and, occasionally, complete vancomycin resistance. More recently, an association has been established between poor outcome and infections with strain...

  14. Comparison of shrinkage related properties of various patch repair materials

    Science.gov (United States)

    Kristiawan, S. A.; Fitrianto, R. S.

    2017-02-01

    A patch repair material has been developed in the form of unsaturated polyester resin (UPR)-mortar. The performance and durability of this material are governed by its compatibility with the concrete being repaired. One of the compatibility issue that should be tackled is the dimensional compatibility as a result of differential shrinkage between the repair material and the concrete substrate. This research aims to evaluate such shrinkage related properties of UPR-mortar and to compare with those of other patch repair materials. The investigation includes the following aspects: free shrinkage, resistance to delamination and cracking. The results indicate that UPR-mortar poses a lower free shrinkage, lower risk of both delamination and cracking tendency in comparison to other repair materials.

  15. Reliability and safety engineering

    CERN Document Server

    Verma, Ajit Kumar; Karanki, Durga Rao

    2016-01-01

    Reliability and safety are core issues that must be addressed throughout the life cycle of engineering systems. Reliability and Safety Engineering presents an overview of the basic concepts, together with simple and practical illustrations. The authors present reliability terminology in various engineering fields, viz.,electronics engineering, software engineering, mechanical engineering, structural engineering and power systems engineering. The book describes the latest applications in the area of probabilistic safety assessment, such as technical specification optimization, risk monitoring and risk informed in-service inspection. Reliability and safety studies must, inevitably, deal with uncertainty, so the book includes uncertainty propagation methods: Monte Carlo simulation, fuzzy arithmetic, Dempster-Shafer theory and probability bounds. Reliability and Safety Engineering also highlights advances in system reliability and safety assessment including dynamic system modeling and uncertainty management. Cas...

  16. OSS reliability measurement and assessment

    CERN Document Server

    Yamada, Shigeru

    2016-01-01

    This book analyses quantitative open source software (OSS) reliability assessment and its applications, focusing on three major topic areas: the Fundamentals of OSS Quality/Reliability Measurement and Assessment; the Practical Applications of OSS Reliability Modelling; and Recent Developments in OSS Reliability Modelling. Offering an ideal reference guide for graduate students and researchers in reliability for open source software (OSS) and modelling, the book introduces several methods of reliability assessment for OSS including component-oriented reliability analysis based on analytic hierarchy process (AHP), analytic network process (ANP), and non-homogeneous Poisson process (NHPP) models, the stochastic differential equation models and hazard rate models. These measurement and management technologies are essential to producing and maintaining quality/reliable systems using OSS.

  17. Within- and between-session reliability of medial gastrocnemius architectural properties

    Directory of Open Access Journals (Sweden)

    JJ McMahon

    2016-05-01

    Full Text Available This study aimed to determine the within- and between-session reliability of medial gastrocnemius (MG architecture (e.g. muscle thickness (MT, fascicle length (FL and pennation angle (PA, as derived via ultrasonography followed by manual digitization. A single rater recorded three ultrasound images of the relaxed MG muscle belly for both legs of 16 resistance trained males, who were positioned in a pronated position with their knees fully extended and the ankles in a neutral (e.g. 90° position. A subset of participants (n = 11 were retested under the same conditions ~48-72 hours after baseline testing. The same rater manually digitized each ultrasound image on three occasions to determine MG MT, FL and PA before pooling the data accordingly to allow for within-image (n = 96, between-image (n = 32 and between-session reliability (n = 22 to be determined. Intraclass correlation coefficients (ICCs demonstrated excellent within-image (ICCs = 0.99-1.00, P < 0.001 and very good between-image (ICCs = 0.83-0.95, P < 0.001 and between-session (ICCs = 0.89- 0.95, P < 0.001 reliability for MT, FL and PA. Between-session coefficient of variation was low (≤ 3.6% for each architectural parameter and smallest detectible difference values of 10.6%, 11.4% and 9.8% were attained for MT, FL and PA, respectively. Manually digitizing ultrasound images of the MG muscle at rest yields highly reliable measurements of its architectural properties. Furthermore, changes in MG MT, FL and PA of ≥ 10.6%, 11.4% and 9.8% respectively, as brought about by any form of intervention, should be considered meaningful.

  18. Reliability of software

    International Nuclear Information System (INIS)

    Kopetz, H.

    1980-01-01

    Common factors and differences in the reliability of hardware and software; reliability increase by means of methods of software redundancy. Maintenance of software for long term operating behavior. (HP) [de

  19. Mechanical reliability of bulk high Tc superconductors

    International Nuclear Information System (INIS)

    Freiman, S.W.

    1990-01-01

    Most prospective applications for high T c superconductors in bulk form, e.g. magnets, motors, will require appreciable mechanical strength. Work at NIST [National Institute of Standards and Technology] has begun to address issues related to mechanical reliability. For example, recent studies on Ba-Y-Cu-O have shown that the intrinsic crack growth resistance, K IC , of crystals of this material is even smaller than was first reported, less than that of window glass, and is sensitive to moisture. Processing conditions, particularly sintering and annealing atmosphere, have been shown to have a major influence on microstructure and internal stresses in the material. Large internal stresses result from the tetragonal to orthorhombic phase transformation as well as the thermal expansion anisotropy in the grains of the ceramic. Because stress relief is absent, microcracks form which have a profound influence on strength

  20. Hawaii electric system reliability.

    Energy Technology Data Exchange (ETDEWEB)

    Silva Monroy, Cesar Augusto; Loose, Verne William

    2012-09-01

    This report addresses Hawaii electric system reliability issues; greater emphasis is placed on short-term reliability but resource adequacy is reviewed in reference to electric consumers' views of reliability %E2%80%9Cworth%E2%80%9D and the reserve capacity required to deliver that value. The report begins with a description of the Hawaii electric system to the extent permitted by publicly available data. Electrical engineering literature in the area of electric reliability is researched and briefly reviewed. North American Electric Reliability Corporation standards and measures for generation and transmission are reviewed and identified as to their appropriateness for various portions of the electric grid and for application in Hawaii. Analysis of frequency data supplied by the State of Hawaii Public Utilities Commission is presented together with comparison and contrast of performance of each of the systems for two years, 2010 and 2011. Literature tracing the development of reliability economics is reviewed and referenced. A method is explained for integrating system cost with outage cost to determine the optimal resource adequacy given customers' views of the value contributed by reliable electric supply. The report concludes with findings and recommendations for reliability in the State of Hawaii.