Artigos de revistas: "Critical stress intensity factor"

1

Dharmarajan, N., e C. Vipulanandan. "Critical stress intensity factor of epoxy mortar". Polymer Engineering and Science 28, n.º 18 (setembro de 1988): 1182–91. http://dx.doi.org/10.1002/pen.760281808.

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Daud, M. A. M., Zainuddin Sajuri, Mohd Zaidi Omar e Junaidi Syarif. "Critical Stress Intensity Factor Determination for AZ61 Magnesium Alloy". Key Engineering Materials 462-463 (janeiro de 2011): 1121–26. http://dx.doi.org/10.4028/www.scientific.net/kem.462-463.1121.

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A stress intensity factor K was used as a fracture parameter to determine the plane strain fracture toughness KIC of AZ61 magnesium alloy using a single edge notch bend (SENB) specimen in accordance to ASTM E399 testing method. Five different specimen thicknesses of 2 to 10 mm were used in the test. A sharp fatigue pre-crack was initiated and propagated to half of specimen width at a constant crack propagation rate of about 1 x 10-8 m/cycle before the specimen was loaded in tension until the fracture stress is reached and then rapid fracture occurred. The fracture toughness KC values obtained for different thicknesses showed that KC value decreased with increasing specimen thickness. The highest KC value obtained was 16.5 MPa√m for 2 mm thickness specimen. The value of KC became relatively constant at about 13 MPa√m when the specimen thickness exceeds 8 mm. This value was then considered as the plane strain fracture toughness KIC of AZ61 magnesium alloy. Calculation of the minimum thickness requirement for plane strain condition and the size of the shear lips of the fracture surface validate the obtained KIC value.

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3

Zarzycki, J. "Critical stress intensity factors of wet gels". Journal of Non-Crystalline Solids 100, n.º 1-3 (março de 1988): 359–63. http://dx.doi.org/10.1016/0022-3093(88)90046-4.

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Zheng, Heng Xiang, e Cai Ying Chen. "Research on Interface Critical Fracture of Different Materials Based on Critical Fracture Curve". Applied Mechanics and Materials 204-208 (outubro de 2012): 3090–93. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.3090.

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In order to get the interface fracture curve of different materials under the four-point loading test pieces, firstly the displacement of fracture interface was obtained based on the finite element method. Then the first and second stress intensity factors of two different materials interface cracks in a beam specimen were calculated by the extrapolation method. Comprehensively considered the type of fracture specimen and the relative proportions between first and second section stress intensity, the variables K' , the first and second stress intensity factor were calculated according to the observed values of fracture load when the fissure appeared. By regression analysis of a six-groups of rock-concrete specimens with prefabricated fissure, the interface fracture criterion of different materials was got which was the interface fracture curve of rock-concrete samples. At last the calculated results of this method were compared and verified with the other related research results.

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SATO, Kiyoshi, Hisato YAMAMOTO, Atsushi TAYA e Hiroyuki OKUYAMA. "Influence of Moisture Content on Critical Stress Intensity Factor of Wood." Journal of the Society of Materials Science, Japan 49, n.º 4 (2000): 365–67. http://dx.doi.org/10.2472/jsms.49.365.

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Meriem-Benziane, Madjid, Gadi Ibrahim, Zahloul Hamou e BelAbbes Bachir-Bouiadjra. "Stress intensity factor investigation of critical surface crack in a cylinder". Advances in Materials and Processing Technologies 1, n.º 1-2 (3 de abril de 2015): 36–42. http://dx.doi.org/10.1080/2374068x.2015.1111702.

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Yoshihara, Hiroshi. "Simple estimation of critical stress intensity factors of wood by tests with double cantilever beam and three-point end-notched flexure". Holzforschung 61, n.º 2 (1 de março de 2007): 182–89. http://dx.doi.org/10.1515/hf.2007.032.

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Abstract Simple equations are proposed for calculation of critical stress intensity factors by tests using double cantilever beam (DCB) and three-point end-notched flexure (3ENF). The calculation modes are named here as modes I and II and are based on the beam theory and 95 previously published data on the elasticity properties of woods. The validity of the data was examined on specimens of western hemlock wood with various crack lengths. The influence of the elastic properties is more significant on the stress intensity factor calculated in mode I than that calculated in mode II. Further work is needed, particularly for measuring the mode I stress intensity factor. However, it is obvious from the experiments with western hemlock that the critical stress intensity factors can be determined by the equations proposed here.

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Anam, Khairul, e Chih Kuang Lin. "Thermal Stress Intensity Factors of Crack in Solid Oxide Fuel Cells". Applied Mechanics and Materials 493 (janeiro de 2014): 331–36. http://dx.doi.org/10.4028/www.scientific.net/amm.493.331.

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Structural durability is the main focus of solid oxide fuel cells (SOFCs) development which is affected by the thermal stress caused by considerable CTE mismatch between components and thermal gradient. In this paper we investigate the thermal stress intensity factor for mode I, mode II and mode III of positive electrode-electrolyte-negative electrode (PEN) at room temperature and steady stage for an initial crack size of 10 μm. A commercial finite element analysis (FEA) was used to find the highly stressed regions in PENs and calculate the thermal stress intensity factors. The stress distributions are calculated at uniform room temperature and at steady stage with a non-uniform temperature profile. The thermal stress intensity factors are calculated for various principal directions at the location having the greatest maximum principal stress at room temperature and steady stage. The critical stress regions are identified based on the maximum principal stress at room temperature and steady stage. The maximum principal stress is of 53.45 MPa and 45.12 MPa in principal direction of-43.97° and-42.37° at room temperature and steady stage, respectively. The mixed-mode stress intensity factor including mode I, mode II, and mode III is calculated due to multi-axial thermal stresses. However, the stress intensity factor for mode I have a highest value compared to those for modes II and III. The principal direction has an effect on the thermal stress intensity factor for the critical region with the greatest maximum principal stress. All the calculated stress intensity factors in the present study are less than the corresponding fracture toughness given in the literature, ensuring the structural integrity for the given planar SOFC stack.

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9

Abuzaid, Ahmed, Meftah Hrairi e Mohd Sultan Dawood. "Mode I Stress Intensity Factor for a Cracked Plate with an Integrated Piezoelectric Actuator". Advanced Materials Research 1115 (julho de 2015): 517–22. http://dx.doi.org/10.4028/www.scientific.net/amr.1115.517.

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The fracture performance of cracked structures is dominated by singular stress in the crack tip vicinity. In fracture mechanics most interest is focused on stress intensity factors, which describe the singular stress field ahead of a crack tip and govern fracture of structures when a critical stress intensity factor is reached. In the present work linear fracture mechanics is applied in order to obtain the fracture toughness parameters of a cracked plate integrated with piezoelectric actuator under mode I loading. Analytical model was derived to represent the relation between piezoelectric parameters and stress intensity factor and energy release rate. The results indicate that the stress intensity factor decreases linearly with the application of the different piezoelectric actuator voltages.

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10

Toribio, J., F. J. Ayaso, B. González, J. C. Matos, D. Vergara e M. Lorenzo. "Critical stress intensity factors in steel cracked wires". Materials & Design 32, n.º 8-9 (setembro de 2011): 4424–29. http://dx.doi.org/10.1016/j.matdes.2011.03.064.

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Adams, George G. "Critical value of the generalized stress intensity factor for a crack perpendicular to an interface". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 471, n.º 2183 (novembro de 2015): 20150571. http://dx.doi.org/10.1098/rspa.2015.0571.

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When a crack tip impinges upon a bi-material interface, the order of the stress singularity will be equal to, less than or greater than one-half. The generalized stress intensity factors have already been determined for some such configurations, including when a finite-length crack is perpendicular to the interface. However, for these non-square-root singular stresses, the determination of the conditions for crack growth are not well established. In this investigation, the critical value of the generalized stress intensity factor for tensile loading is related to the work of adhesion by using a cohesive zone model in an asymptotic analysis of the separation near the crack tip. It is found that the critical value of the generalized stress intensity factor depends upon the maximum stress of the cohesive zone model, as well as on the Dundurs parameters ( α and β ). As expected this dependence on the cohesive stress vanishes as the material contrast is reduced, in which case the order of the singularity approaches one-half.

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Mitchell, DMR, e ER Abril. "The Influence of Initial Crack Length on Critical Stress Intensity Factor K1". Journal of Testing and Evaluation 34, n.º 5 (2006): 12660. http://dx.doi.org/10.1520/jte12660.

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Nazmus Sakib, A. R., e Ashfaq Adnan. "On the size-dependent critical stress intensity factor of confined brittle nanofilms". Engineering Fracture Mechanics 86 (maio de 2012): 13–22. http://dx.doi.org/10.1016/j.engfracmech.2012.02.003.

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Stupishin, Leonid, Victor Kabanov e Aleksander Masalov. "Fracture Resistance of Bended Glued Timber Elements with Flaws". Advanced Materials Research 988 (julho de 2014): 363–66. http://dx.doi.org/10.4028/www.scientific.net/amr.988.363.

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The test results for deriving of the dependencies of critical stress intensity factors on significant agents are presented for glued laminated timber. The dependencies of critical stress intensity factors on moisture content, width of cross section for I and II forms of fracture are investigated. For the second fracture form the influence of glue joint thickness within the limits of 0.07 - 0.35 mm was estimated. The influence on critical stress intensity factor was estimated also for the moisture content of wood within the limits of 12-35%, for crack front width within the limits of 30 - 140 mm, for loading velocity within the limits of 16 - 32 kN/min, for the form of crack tip, and the location of crack - in glue joint or in wood.

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15

Vasovic, Ivana, Stevan Maksimovic, Katarina Maksimovic, Slobodan Stupar, Gordana Bakic e Mirko Maksimovic. "Determination of Stress Intensity Factors in Low Pressure Turbine Rotor Discs". Mathematical Problems in Engineering 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/304638.

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An attention in this paper is focused on the stress analysis and the determination of fracture mechanics parameters in low pressure (LP) turbine rotor discs and on developing analytic expressions for stress intensity factors at the critical location of LP steam turbine disc. Critical locations such as keyway and dovetail area experienced stress concentration leading to crack initiation. Major concerns for the power industry are determining the critical locations with one side and fracture mechanics parameters with the other side. For determination of the critical locations in LP turbine rotor disc conventional finite elements are used here. For this initial crack length and during crack growth it is necessary to determine SIFs. In fatigue crack growth process it is necessary to have analytic formulas for the stress intensity factor. To determine analytic formula for stress intensity factor (SIF) of cracked turbine rotor disc special singular finite elements are used. Using discrete values of SIFs which correspond to various crack lengths analytic formula of SIF in polynomial forms is derived here. For determination of SIF in this paper, combinedJ-integral approach and singular finite elements are used. The interaction of mechanical and thermal effects was correlated in terms of the fracture toughness.

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VAKULENKO, Igor, Svetlana PROYDAK e Hangardas ASKEROV. "The calculation of stress intensity factor steel of railway wheels". Scientific Journal of Silesian University of Technology. Series Transport 109 (1 de dezembro de 2020): 187–93. http://dx.doi.org/10.20858/sjsutst.2020.109.17.

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From an analysis of the dependence complex of carbon steel properties on structural parameters, it was found that for an isostructural state, the influence of austenite grain size on impact strength exceeds the dependence on carbon content. As a result of explaining correlation relationships between individual mechanical characteristics, to evaluate critical stress intensity factor, a relationship is proposed based on the use of impact strength. The proportionality coefficient in proposed dependence is determined by ratio of elongation to narrowing at tensile test.

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17

Sundaresan, S., e B. Nageswara Rao. "Stress Intensity at the Initiation of Instability by R Curve". Applied Mechanics and Materials 592-594 (julho de 2014): 1160–64. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.1160.

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The life expectancy or failure of aerospace pressure vessels is evaluated by the critical stress intensity determined by the crack growth resistance curve of a material. Load versus crack mouth opening displacement data is generated from the Compact Tension specimens made from the weld joints of maraging steel rocket motor segments. The steps involved to generate critical stress intensity factor is explained. A power law is adopted to model the crack extension in terms of stress intensity factor and determine the maximum failure load of weld specimens. Maximum failure loads of CT specimens obtained by test and analysis are presented.

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Chen, Teng Hui. "Fracture Analysis for Attaching Fiber Reinforced Composite on V-Notch Wedge Structure". Materials Science Forum 909 (novembro de 2017): 133–42. http://dx.doi.org/10.4028/www.scientific.net/msf.909.133.

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Sharp V-notches with various angles often appear in engineering structures. When being loaded, the high stress at the apex could result in crack propagation on the structure and further fracture. For this reason, safety evaluation should be emphasized for products or engineering structures with such geometric characteristics. Sharp V-notches are regarded as wedge structures that the above situations seriously and often appear on brittle materials. Regarding the stress intensity factor K of the driving force for wedge structure failure, Chen, Dunn, and Seweryn, with numerical analysis for the fracture experiment, explained that the critical stress intensity factor Kc for single isotropic material fracture could be the intensity failure specification for wedge structures. Nevertheless, V-notched brittle materials are likely to receive great stress over the surface elastic energy of the structure when being loaded, causing brittle failure at the apex. When the high-strength and light-weight composite material is attached to reinforce the surface of brittle materials, the energy is reinforced to enhance the critical stress intensity factor of the overall structure, aiming to improve the failure of brittle materials resulted from stress singularity. This paper therefore tends to discuss the effects of the composite attachment, layer, and fiber reinforced direction on the critical stress intensity factor when the structure is being fractured.

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Tumanov, A. V., e N. V. Boychenko. "Interpretation of the generalized parameter of the probability of failure through the plastic stress intensity factor". PNRPU Mechanics Bulletin, n.º 1 (15 de dezembro de 2021): 86–94. http://dx.doi.org/10.15593/perm.mech/2021.1.09.

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The main purpose of this work is to statistically analyze the fracture toughness of compact specimens made of S55C steel in terms of elastic and plastic stress intensity factors. The fracture toughness tests results at three-point bending were used for a comparative statistical analysis of the fracture parameters. Five type of specimen configuration with various thicknesses were tested at a constant ratio between crack length and specimen width. The critical loads were obtained as a tests result for various combinations of crack length and specimen thickness. In addition, uniaxial tensile tests were carried out to determine the main mechanical properties of the material. Obtained material properties were used in numerical calculations. Numerical calculations were carried out to determine the elastic and plastic stress intensity factors. Three-dimensional finite element analysis was performed on the basis of the experimental data on curvilinear crack front positions in tested specimens. The crack tip stress-strain fields were obtained for each of the tested samples as a result of numerical calculations. These fields were used to calculate the values of the plastic intensity factors along the curvilinear crack fronts. A statistical analysis of the fracture toughness of compact specimens made of S55C steel was carried out based on the obtained critical values of elastic and plastic stress intensity factors. The advantages of using the plastic stress intensity factor as a generalized parameter for the fracture probability are demonstrated. In addition, the sensitivity of the plastic stress intensity factor to constraint effects avoids the introduction of additional parameters into the statistical models.

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Zebri, O., H. El Minor e A. Bendarma. "Evolution of Tenacity in Mixed Mode Fracture – Volumetric Approach". Mechanics and Mechanical Engineering 22, n.º 4 (2 de setembro de 2020): 931–38. http://dx.doi.org/10.2478/mme-2018-0073.

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AbstractIn fracture mechanics most interest is focused on stress intensity factors, which describe the singular stress field ahead of a crack tip and govern fracture of a specimen when a critical stress intensity factor is reached. In this paper, stress intensity factors which represents fracture toughness of material, caused by a notch in a volumetric approach has been examined, taking into account the specific conditions of loading by examining various U-notched circular ring specimens, with various geometries and boundary conditions, under a mixed mode I+II. The bend specimens are computed by finite element method (FEM) and the local stress distribution was calculated by the Abaqus/CAE. The results are assessed to determine the evolution of the stress intensity factor of different notches and loading distances from the root of notch. This study shows that the tenacity is not intrinsic to the material for all different geometries notches.

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Fang, Qiang. "A Comparative Study of Delayed Hydride Cracking in Zr-3.5Sn-0.8Nb-0.8Mo and Zr-2.5Nb". Materials Science Forum 917 (março de 2018): 207–11. http://dx.doi.org/10.4028/www.scientific.net/msf.917.207.

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A new test procedure for measuring the resistance to delayed hydride cracking was developed. The critical stress intensity factors for delayed hydride cracking and the crack growth velocities of Zr-3.5Sn-0.8Nb-0.8Mo alloy with different heat treatments were evaluated and compared with Zr-2.5Nb. It was found that Delayed Hydride Cracking (DHC) crack growth velocity increases with the alloy strength, and the critical stress intensity factor is independent of heat treatment history or alloy composition.

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Chasiotis, I., S. W. Cho e K. Jonnalagadda. "Fracture Toughness and Subcritical Crack Growth in Polycrystalline Silicon". Journal of Applied Mechanics 73, n.º 5 (10 de dezembro de 2005): 714–22. http://dx.doi.org/10.1115/1.2172268.

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The fracture behavior of polycrystalline silicon in the presence of atomically sharp cracks is important in the determination of the mechanical reliability of microelectromechanical system (MEMS) components. The mode-I critical stress intensity factor and crack tip displacements in the vicinity of atomically sharp edge cracks in polycrystalline silicon MEMS scale specimens were measured via an in situ atomic force microscopy/digital image correlation method. The effective (macroscopic) mode-I critical stress intensity factor for specimens from different fabrication runs was 1.00±0.1MPa√m, where 0.1MPa√m is the standard deviation that was attributed to local cleavage anisotropy and grain boundary effects. The experimental near crack tip displacements were in good agreement with the linearly elastic fracture mechanics solution, which supports K dominance in polysilicon at the scale of a few microns. The mechanical characterization method implemented in this work allowed for direct experimental evidence of incremental (subcritical) crack growth in polycrystalline silicon that occurred with crack increments of 1-2μm. The variation in experimental effective critical stress intensity factors and the incremental crack growth in brittle polysilicon were attributed to local cleavage anisotropy in individual silicon grains where the crack tip resided and whose fracture characteristics controlled the overall fracture process resulting in different local and macroscopic stress intensity factors.

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AMAGAI, Masazumi. "The Effect of Polyimide Surface Chemistry and Morphology on Critical Stress Intensity Factor." Journal of Japan Institute of Electronics Packaging 3, n.º 7 (2000): 569–77. http://dx.doi.org/10.5104/jiep.3.569.

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Yew, C. H., e G. H. Liu. "The Fracture Tip and Critical Stress Intensity Factor of a Hydraulically Induced Fracture". SPE Production & Facilities 8, n.º 03 (1 de agosto de 1993): 171–77. http://dx.doi.org/10.2118/22875-pa.

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VINCENT, J. F. V., D. E. J. SAUNDERS e P. BEYTS. "THE USE OF CRITICAL STRESS INTENSITY FACTOR TO QUANTIFY "HARDNESS" AND "CRUNCHINESS" OBJECTIVELY". Journal of Texture Studies 33, n.º 2 (julho de 2002): 149–59. http://dx.doi.org/10.1111/j.1745-4603.2002.tb01341.x.

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Amagai, Masazumi. "The effect of polyimide surface chemistry and morphology on critical stress intensity factor". Microelectronics Reliability 40, n.º 12 (dezembro de 2000): 2077–86. http://dx.doi.org/10.1016/s0026-2714(00)00024-x.

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Brandt, A. M., e G. Prokopski. "Critical values of stress intensity factor in mode II fracture of cementitious composites". Journal of Materials Science 25, n.º 8 (agosto de 1990): 3605–10. http://dx.doi.org/10.1007/bf00575395.

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SARACOGLU, Goksel. "Using the Stress Concentration Factor in Determining the Fracture Toughness". Mechanics 28, n.º 5 (21 de outubro de 2022): 358–63. http://dx.doi.org/10.5755/j02.mech.31226.

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This paper offers the use of stress concentration factor in determining the critical fracture stress and fracture toughness of polymeric composite materials at various crack length ratios. The stress intensity factor has been turned into a function of the stress concentration factor derived from the maximum stress occurring at the notch tip and the tip stress generated by the force applied to the sample. This conversion allowed the use of a fixed theoretical radius (1.2732 mm) instead of the actual radius of the notch or crack. On the edge cracked three-point bending and tensile samples, the specified method detects the three point bending fracture stresses with a maximum error rate of 1.2%. This study also establishes a relationship between the clamped end and the pin-loaded tensile specimens and states that the underlying mechanism of the stress intensity factor of the clamped end tensile specimen is based on the normalization of the stress intensity factor of the pin-loaded conditions with the geometric correction factor.

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Purba, Muhammad Rafi, Tulus Tulus, M. R. Syahputra e Sawaluddin Sawaluddin. "IMPLEMENTATION OF EXTENDED FINITE ELEMENT METHOD IN CRACK PROPAGATION OF CONCRETE". Journal of Fundamental Mathematics and Applications (JFMA) 5, n.º 1 (1 de julho de 2022): 1–8. http://dx.doi.org/10.14710/jfma.v5i1.14454.

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The Extended Finite Element Method is a numerical solution based on the Finite Element Method (FEM) XFEM has really become a very important generalization of classical finite element techniques, by establishing a mesh independent generalization of classical finite elements to reduce the mesh-dependent shortcomings of the solution. The application of XFEM in crack simulation should improve the modeling of the crack tip environment and also apply to generalized advanced global failure criteria, which is specifically designed to deal with problems in the engineering field Such as the fracture behaviour model. The purpose of this paper is to identify the application of the Extended Finite Element Method to a technical problem, namely fracture behaviour model. The media used is pure boneless concrete modelled with COMSOL Multiphysics 5.6 software by combining stress ratio, lateral strain due to axial loading, concrete density, and crack growth rate. The crack growth process provides initial prolonged growth along with the increase in crack size. In the end, the growth is faster. The reason for this accelerated growth is the stress intensity factor at the crack tip. As the crack grows, the stress intensity factor increases, leading to faster growth. The crack grows until it reaches a critical value, and fracture occurs. The test results obtained the cause of failure: the critical stress intensity is exceeded. See a comparison of crack size and stress cycle as the crack size increases. This accelerated growth is because the growth rate depends on the stress intensity factor at the crack tip, and the stress intensity factor depends on the crack size. As the crack grows, the stress intensity factor increases, leading to faster growth. The crack grows to a critical size, and failure occurs. The results show a relatively strong relationship between increasing crack size and increasing crack growth rate.

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Osaretin, Meshach, Sylvester Onyemaechi Edelugo, Patrick Udeme Akpan, Cornelius Ogbodo Anayo Agbo, Paul Amaechi Ozor e Nita Inderlal Sukdeo. "Stress Intensity Factor of E-Glass Fiber Reinforced Polyester Composites". Materials Science Forum 1115 (29 de fevereiro de 2024): 9–19. http://dx.doi.org/10.4028/p-nld6we.

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In order to analyze the stress concentration impact, intensity close to the zone of the crack tip, this work examines the in-plane SIF(SIF) of composite plates utilizing measured crack tip opening displacement (CTOD). The test specimens' E-glass fiber mats were arranged in various ply configurations. The ASTM standards utilized for researching mode I fracture of composite materials served as the foundation for the compact tension (CT) specimen. The mode I, KI Stress intensity factor (SIF), and critical stress, c, were calculated for each specimen along the fracture length propagation based on the experiments. It was found that the SIF is directly proportional with fracture length, or a/W, for all E-glass fiber laminate cases tested. The KIC is often higher in thinner laminates. The presence of woven roving increases the SIF and hence the toughness of the laminate.

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Kravchuk, Andriy, e Ievgen Kondriakov. "Determination of fracture toughness for steel 22k from the results of tests of different types specimens". Bulletin of the National Technical University «KhPI» Series: New solutions in modern technologies, n.º 3(9) (18 de outubro de 2021): 20–25. http://dx.doi.org/10.20998/2413-4295.2021.03.03.

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Nowadays, in various industries, in particular in nuclear energy, to determine the fracture toughness, along with standard tests of compact specimens, which are quite expensive and complex, methods are developed to determine these characteristics by impact tests of Charpy specimens using different correlations between Charpy impact fracture energy (CVN) and critical stress intensity factor (J-integral). The paper analyzes correlation and analytical methods, the authors of which consider them universal for a certain class of steels. Correlation methods are divided into one-stage and two-stage. One-stage methods allow to obtain the value of the critical stress intensity factor by the known fracture energy. Two-stage methods in the first stage offer the calculation of the dynamic critical stress intensity factor, in the second the temperature shift and obtaining a static critical stress intensity factor. Analytical methods according to the іmpact fracture diagram of the specimen allow to construct a J-R curve and calculate the value of the J-integral. A series of fracture tests of CT specimens made of heat-resistant steel 22K was carried out, the reference temperature T0 was determined according to the single-temperature method of the ASTM-1921 standard and the Master curve was constructed. A series of standard Charpy specimens impact tests in the temperature range -50…+100°С was performed using an instrumented drop-weight impact testing machine equipped with a high-speed registration system. According to the results of Charpy specimens impact tests, the fracture toughness were determined using different methods. It is established that both analytical and correlation methods cannot be universal and can be used to determine the fracture toughness of 22K steel. Therefore, a new exponential correlation was proposed between the fracture energy of the Charpy specimens and the critical stress intensity factor for heat-resistant steel 22K.

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Náhlík, Luboš, Kateřina Štegnerová, Pavel Hutař e Zdeněk Majer. "Critical Value for Crack Propagation from Sharp V-Notch". Key Engineering Materials 592-593 (novembro de 2013): 177–80. http://dx.doi.org/10.4028/www.scientific.net/kem.592-593.177.

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The contribution is focused on estimation of a critical value of generalized stress intensity factor for crack propagation from sharp V-notches. Stress distribution around the tip of the V-notch is described on the base of generalized linear elastic fracture mechanics, because V-notch is a singular stress concentrator with stress singularity exponent different from 0.5 (depending on V-notch opening angle). Then also stability criteria based on strain energy density factor and average critical stress are generalized for the stress singularity different from 0.5. Using FE analysis the critical stresses for crack initiation was estimated and compared with experimental data from the literature.

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Young, A., D. P. Rooke e D. J. Cartwright. "Numerical study of balanced patch repairs to cracked sheets". Aeronautical Journal 93, n.º 929 (novembro de 1989): 327–34. http://dx.doi.org/10.1017/s0001924000017255.

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SummaryThe effects on the stress intensity factor of bonding repair patches over a crack in a large sheet under uniaxial loading are studied using two simple numerical models. The variation of the stress intensity factor with increasing crack length is investigated and results for repairs involving large elliptical patches are found to agree with a closed-form approximation. Further cases are considered where the patch is either rectangular in shape or less than a certain critical size. For such repairs the closed-form approximation for the stress intensity factor is shown to be unsuitable.

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Kiciak, A., G. Glinka e D. J. Burns. "Calculation of Stress Intensity Factors and Crack Opening Displacements for Cracks Subjected to Complex Stress Fields". Journal of Pressure Vessel Technology 125, n.º 3 (1 de agosto de 2003): 260–66. http://dx.doi.org/10.1115/1.1593080.

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Fatigue cracks in shot peened and case hardened notched machine components and high-pressure vessels are subjected to the stress fields induced by the external load and the residual stress resulting from the surface treatment or autofrettage. Both stress fields are usually nonuniform and available handbook stress intensity factor solutions are in most cases unavailable for such configurations, especially in the case of two-dimensional surface breaking cracks such as semi-elliptical and quarter-elliptical cracks at notches. The method presented in the paper makes it possible to calculate stress intensity factors for such cracks and complex stress fields by using the generalized weight function technique. It is also shown that the generalized weight functions make it possible to calculate the crack opening displacement field often used in the determination of the critical load or the critical crack size.

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Štegnerová, Kateřina, Luboš Náhlík e Pavel Hutař. "Influence of the V-Notch Opening Angle on Critical Applied Force Values for the Crack Initiation from the Sharp V-Notch". Key Engineering Materials 627 (setembro de 2014): 165–68. http://dx.doi.org/10.4028/www.scientific.net/kem.627.165.

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The aim of this paper is to estimate a value of the critical applied force for a crack initiation from the sharp V-notch tip. The classical approach of the linear elastic fracture mechanics (LELM) was generalized, because the stress singularity exponent differs from 0.5 in studied case. The value of the stress singularity exponent depends on the V-notch opening angle. The finite element method was used for a determination of stress distribution in the vicinity of the sharp V-notch tip and for the estimation of the generalized stress intensity factor depending on the V-notch opening angle. Critical value of generalized stress intensity factor was obtained by using stability criterion based on the tangential stress component averaged over a critical distancedfrom the V-notch tip. Calculated values of the critical applied force were compared with experimental data taken from the literature.

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Heidarvand, Majid, Naser Soltani e Farshid Hajializadeh. "Experimental and numerical determination of critical stress intensity factor of aluminum curved thin sheets under tensile stress". Journal of Mechanical Science and Technology 31, n.º 5 (maio de 2017): 2185–95. http://dx.doi.org/10.1007/s12206-017-0414-8.

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Zhang, Feng, Xin Wang, Rumin Teng, Xiaoguang Guo e Yuanyou Wang. "Study on Stress Intensity Factor of the Pit-Crack Model for Portal Crane Girders". Sustainability 15, n.º 9 (6 de maio de 2023): 7621. http://dx.doi.org/10.3390/su15097621.

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In shipbuilding gantry cranes in long-term service in the coastal humid salt-spray environment, the main beam is affected in many places by corrosion fatigue-formed corrosion pits, affecting the structural strength of the main beam. This paper focuses on the impact of corrosion-generated pits under the conditions of crack nucleation. Corrosion fatigue crack nucleation is a local damage evolution process and the stress intensity factor criterion is one of the critical conditions to discern whether a crack sprouts at the corrosion pit. This paper establishes a corrosion pit-crack model based on the overall finite element model of the portal crane, and uses ANSYS software to simulate the stress intensity factor under complex boundary conditions. The results show that the different sizes and depth-to-diameter ratio of the pits greatly affect the value of the stress intensity factor and the stress concentration phenomenon may be the main factor causing the emergence of cracks; the change in the size of the pits on the stress intensity factor is not obvious, but with the increase in the depth-to-diameter ratio of the pits, the stress intensity factor of the pit-crack model is significantly increased. According to the hypothesis of semi-ellipsoidal pitting, the relationship between the stress intensity factor and the stress concentration factor at the pit is proposed, and its calculation results are within 5% error compared with the finite element method, and it is found that the effect of the etch pit on the stress intensity factor is positively correlated with the stress concentration factor; with the increase in the etch pit depth–diameter ratio, the crack budding location changes with the change in the stress concentration location, and the crack is more likely to be generated from the shoulder of the etch pit when the depth–diameter ratio of etch pit exceeds 1.

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Sevcik, Martin, Pavel Hutar, Lubos Nahlik, Ralf Lach, Zdenek Knesl e Wolfgang Grellmann. "Crack propagation in a welded polyolefin pipe". International Journal of Structural Integrity 3, n.º 2 (25 de maio de 2012): 148–57. http://dx.doi.org/10.1108/17579861211235174.

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PurposeThe purpose of this paper is to study the effect of the material inhomogeneity on crack behavior initiated both axially and circumferentially in or near the butt weld and to discuss consequences on residual lifetime of the welded structure.Design/methodology/approachA three‐dimensional numerical model of pipe weld with smooth and continuous change of material properties has been used to study the fracture behavior of the cracked pipe structure. The stress intensity factor was considered as a parameter controlling the fracture behavior. The semi‐elliptical shape of the crack front was estimated under assumption of constant stress intensity factor along the crack front.FindingsAccording to the results obtained in the paper the following conclusions were deduced. First, the most critical location of the crack is in the middle of the inhomogeneous region (weld center) regardless of the crack orientation. The stress intensity factor is substantially higher than in the case of a crack located in the homogenous pipe. Second, with regard to crack shapes, the circumferentially oriented cracks are practically identical regardless to the crack location if compared with the axial cracks. Third, the stress intensity factors of axially‐oriented cracks are approximately twice higher than in the case of circumferential cracks. This implies that the cracks are more likely to grow in an axial direction.Originality/valueThe results described in the paper can be used for estimation of critical crack length or for estimation of the critical applied inner pressure of medium transported in the pipe and are of paramount importance for service life estimations of polymer welded pipes in actual use.

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Ahmed Nassar, Ameen. "Evaluation of Critical Stress Intensity Factor (Kic) for Plates Using New Crack Extension Technique". Engineering and Technology Journal 31, n.º 4A (1 de abril de 2013): 730–40. http://dx.doi.org/10.30684/etj.31.4a.11.

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Ji, Chenlong, Zhongliang Zheng, Ziming Qin e Hao Xue. "Investigation of Multi-Factor Stress Corrosion Cracking Failure of Safe-End Feedwater Lines of Submarine Power System". Materials 17, n.º 6 (18 de março de 2024): 1381. http://dx.doi.org/10.3390/ma17061381.

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The corrosion process under the complex safe-end feedwater line conditions was investigated via experimental lab testing and numerical simulation. The corrosion of safe-end feedwater lines was controlled through the combination of galvanic corrosion, residual stress, and flow velocity. Firstly, galvanic corrosion occurred once the 20 steel was welded with 316L stainless steel. The pitting corrosion could be observed on the 20 steel side of the weld joint. Secondly, a vortex flow was detected around the welding bump and within the pits. The growth of the pits was accelerated in both the vertical and horizontal directions. Finally, under the residual stress condition, the stress intensity factor (K) at the bottom of the pits was easier to reach than the critical stress intensity factor (KISCC). Then, pitting was transformed into stress corrosion cracking which then propagated along the weld line. Therefore, the critical factor inducing the failure of safe-end feedwater lines was the combined action of galvanic corrosion, residual stress, and flow velocity.

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Ding, Jun, Xia Huang, Wen Zhong Li e Xiang Guo Zeng. "Molecular Dynamics Simulation for Crack Propagation in Magnesium Alloy". Advanced Materials Research 472-475 (fevereiro de 2012): 2211–16. http://dx.doi.org/10.4028/www.scientific.net/amr.472-475.2211.

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In this work, crack initiation due to the pre-existence of an initial crack has been predicted according to the criterion of critical stress intensity factor and succeeding crack evolution and propagation are also been performed using molecular dynamic (MD) method in combination with finite element method (FEM). The modified embedded atom method potentials were employed to characterize the interaction among atoms in magnesium alloy in MD simulation. Finite element simulations have been first conducted to provide subsequent MD simulation with boundary conditions constrained at the atoms. The MD simulation shows that atoms around crack arrange disorderly, aggravate rapidly suggesting the onset of crack initiation and eventually results in the failure of alloy specimen. It helps to evaluate the value of critical stress intensity factor for a specific crack configuration, which provides an effective way to determine the stress intensity factor for the specified configuration.

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Hua, Wen, Jigang Xu, Shiming Dong, Jizhou Song e Qingyuan Wang. "Effect of Confining Pressure on Stress Intensity Factors for Cracked Brazilian Disk". International Journal of Applied Mechanics 07, n.º 03 (junho de 2015): 1550051. http://dx.doi.org/10.1142/s1758825115500519.

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An analytical model, verified by the finite element method, is developed to study the effect of confining pressure on stress intensity factors for the cracked Brazilian disk. The closed-form expressions for stress intensity factors under both confining pressure and diametric forces are obtained based on the weight function method. The results show that the confining pressure has no effect on the mode II stress intensity factor; however, the mode I stress intensity factor decreases with the increase of confining pressure and the change may be above 100% for a large confining pressure. In addition, the effect of confining pressure on the loading condition of pure mode II crack is also investigated. It is shown that the critical loading angle for pure mode II crack decreases as the confining pressure increases. Depending on the magnitude of confining pressure, the failure problem of a disk may be no longer a pure fracture problem. These results have established the theoretical foundation to measure the fracture toughness of materials under confining pressure.

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Kim, Hyung Jin, Sung Wi Koh, Jae Dong Kim e Byung Tak Kim. "Effect of the Size of the Reinforcement Phased on the Properties of Silica-Filled Composites". Materials Science Forum 544-545 (maio de 2007): 267–70. http://dx.doi.org/10.4028/www.scientific.net/msf.544-545.267.

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In this study, the mechanical properties of silica-filled epoxy resin composites with average silica particle diameter of 6-33m were investigated at ambient temperature and pin-ondisc friction test was conducted for this. Experimental results demonstrated that mechanical properties such as flexural strength, flexural modulus and critical stress intensity factor depend on average particle diameter. The flexural strength decrease with increase of particle size whereas the critical stress intensity factor increases with increases of particle size. Wear rates of silica-filled composites are below a half those of unfilled epoxy. Fracture surface analysis was discussed based on SEM examination.

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Ikeda, Toru, Isao Arase, Yuya Ueno, Noriyuki Miyazaki, Nobutaka Ito, Mami Nagatake e Mitsuru Sato. "Strength Evaluation of Plastic Packages During Solder Reflow Process Using Stress Intensity Factors of V-Notch". Journal of Electronic Packaging 125, n.º 1 (1 de março de 2003): 31–38. http://dx.doi.org/10.1115/1.1525244.

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A crack initiated from a V-notch corner in the molding resin, such as a corner of die pad, is one of the main causes of the failure in plastic packages. The stress intensity factors of the asymptotic solution of a corner of jointed dissimilar materials are utilized for the evaluation of a solder reflow crack in a quad flat package (QFP). First, we estimate the critical vapor pressure, which causes a crack from a corner in the molding resin, using the critical stress intensity factor of a V-notch corner. This critical factor was measured by V-notched three-point bending tests and the displacement extrapolation method along with the three dimensional (3-D) finite element method (FEM). Moisture concentration in the QFP after absorption is analyzed, and vapor pressure caused by the solder reflow process is estimated. The critical moisture absorption time, which results in crack occurrence during the solder reflow process, can be predicted using this evaluation technique. Furthermore, we perform infrared solder reflow tests of the QFP for verifying the present failure evaluation technique.

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SADOVSKAYA, E., e S. LEONOVICH. "RELATIONSHIP OF THE STRESS-INTENSITY COEFFICIENT AT NORMAL SEPARATION AND THE STRENGTH IN TENSION". Herald of Polotsk State University. Series F. Civil engineering. Applied sciences 31, n.º 8 (29 de junho de 2022): 27–31. http://dx.doi.org/10.52928/2070-1683-2022-31-8-27-31.

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This article explores the practical use of the Leonov-Panasyuk model for calculating the stress intensity factor for nanofibre-reinforced concrete using the value of tensile strength in bending of a sample beam of 100×100×400 mm. The study was carried out on different nanoconcrete matrices with three types of fiber fibers. Comparison of the obtained values showed a high degree of convergence with the values of the stress intensity factor obtained from the strength for normal separation in cubes with a notch, from the energy consumption during bending of a beam with a notch. The results confirm that the critical stress intensity factor can be attributed to stable indicators of the crack resistance of nanofiber-reinforced concrete.

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Zhao, Rui-Huan, e J. C. M. Li. "Dynamic Emission of Dislocations From a Moving Crack". Journal of Engineering Materials and Technology 107, n.º 4 (1 de outubro de 1985): 277–81. http://dx.doi.org/10.1115/1.3225819.

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The emission of dislocations from a propagating crack in the mode II or III situations is studied by computer simulation. While the crack is moving the steady state number of dislocations is smaller than the saturation number which could be emitted from a stationary crack and such a steady state number decreases with increasing crack velocity. The effect on the emission process of the applied stress, the lattice friction for dislocation motion and the critical stress intensity factor for dislocation emission is studied. The results include also the plastic zone size, the dislocation distribution, the dislocation-free zone, and the instantaneous crack velocity. The average crack velocity does not depend on the applied stress but depends only on the critical stress intensity factor for dislocation emission. When such a factor is zero as assumed in some theories, the crack does not move at all.

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Erdogan, F. "Slow Crack Growth in Glasses and Ceramics Under Residual and Applied Stresses". Journal of Electronic Packaging 111, n.º 1 (1 de março de 1989): 61–67. http://dx.doi.org/10.1115/1.3226510.

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The problem of slow crack growth under residual stresses and externally applied loads in plates is considered. Even though the technique developed to treat the problem is quite general, in the solution given it is assumed that the plate contains a surface crack and the residual stresses are compressive near and at the surfaces and tensile in the interior. The crack would start growing subcritically when the stress intensity factor exceeds a threshold value. Initially the crack faces near the plate surface would remain closed. A crack-contact problem would, therefore, have to be solved to calculate the stress intensity factor. Depending on the relative magnitudes of the residual and applied stresses and the threshold and critical stress intensity factors, the subcritically growing crack would either be arrested or become unstable. The problem is solved and examples showing the time to crack arrest or failure are discussed.

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Choi, Dong Ho, Hang Yong Choi, Sang Hwan Chung e Hoon Yoo. "Mixed-Mode Fatigue Crack Growth in Orthotropic Steel Decks". Key Engineering Materials 321-323 (outubro de 2006): 733–38. http://dx.doi.org/10.4028/www.scientific.net/kem.321-323.733.

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The strain energy density factor approach under mixed-mode condition is used for the prediction of crack propagation in the orthotropic steel deck specimen, which is similar to that of existing suspension bridges. Stress intensity factor approach is used to compare with strain energy density factor approach for the fatigue crack growth analysis. The stress intensity factors are computed by numerical extrapolation using cracked models for the different crack length. The study shows that the fatigue crack propagation under mixed-mode condition is slower than that under mode I only. Parametric studies on the initial crack length, critical crack length and parameters related to crack growth equations are performed to show the influence of these parameters on the fatigue life.

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Andrianopoulos, N. P., e V. C. Boulougouris. "On an intrinsic relationship between plane stress and plane strain critical stress intensity factors". International Journal of Fracture 67, n.º 1 (maio de 1994): R9—R12. http://dx.doi.org/10.1007/bf00032369.

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Le, Minh-Quy. "Fracture of monolayer germanene: A molecular dynamics study". International Journal of Modern Physics B 32, n.º 22 (20 de agosto de 2018): 1850241. http://dx.doi.org/10.1142/s0217979218502417.

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Molecular dynamics simulations with Tersoff potential were performed to study the fracture properties of monolayer germanene at 300 K. The two-dimensional (2D) Young’s modulus, 2D tensile strength and axial strain at the tensile strength of pristine monolayer germanene are about 36.0 and 37.5 N/m; 5.1 and 4.6 N/m; 21.4 and 15.9%, in the zigzag and armchair directions, respectively. Griffith theory was applied to compute the critical stress intensity factor. Compared to monolayer graphene, the critical stress intensity factor of monolayer germanene is much smaller. Fracture pattern and effects of the initial crack length on the fracture properties are also studied. Results are useful for future design and applications of this 2D material.

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