Effect of welded mechanical heterogeneity on local stress and strain ahead of stationary and growing crack tips

2009 ◽  
Vol 239 (4) ◽  
pp. 628-640 ◽  
Author(s):  
He Xue ◽  
Kazuhiro Ogawa ◽  
Tetsuo Shoji
Keyword(s):  
Local Stress ◽  
Stress And Strain ◽  
Mechanical Heterogeneity ◽  
Growing Crack ◽  
Crack Tips

Effect of Welded Mechanical Heterogeneity on Local Stress and Strain Ahead of Growing Crack Tips in the Piping Welds

2011 ◽  
Author(s):  
Lingyan Zhao ◽  
He Xue ◽  
Wei Tang ◽  
Xiurong Fang
Keyword(s):  
Crack Tip ◽  
Local Stress ◽  
Stress And Strain ◽  
Strain Fields ◽  
Mechanical Heterogeneity ◽  
Constant Loading ◽  
Primary Loop ◽  
Weld Joints ◽  
Growing Crack ◽  
Crack Tips

Primary loop recirculation (PLR) piping weld joints are more susceptible to stress corrosion cracking (SCC). But it is difficult to accurately predict SCC growth rate in PLR piping weld joints because the material and mechanical properties in weld joints are quite complicated. Especially, it is provided that hardening in the weld heat-affected zone (HAZ) might play an important role in promoting SCC growth. Considering welded mechanical heterogeneity, the local stress and plastic strain fields ahead of growing crack tip in 316L PLR piping weld joints are analyzed, the effect of constant stress intensity factor (KI) and constant loading on SCC behaviors of PLR piping weld joints is investigated in this study. The results show that the mechanical fields of SCC tips behave quite differently under constant KI and constant loading because of welded mechanical heterogeneity and advanced crack length, which demonstrate that the effect of constant loading on the stress and strain ahead of the growing crack tip is bigger than that of constant KI.

Mathematical Model of the Effective Properties of a Fiber Reinforced Composite with a Linearly Graded Transition Zone

2010 ◽  
Vol 38 (4) ◽  
pp. 286-307
Author(s):  
Carey F. Childers
Keyword(s):  
Mathematical Model ◽  
Transition Zone ◽  
Effective Properties ◽  
Local Stress ◽  
Stress And Strain ◽  
Fiber Reinforced ◽  
Strain Fields ◽  
Shear Moduli ◽  
Fiber Reinforced Composite ◽  
Reinforced Composite

Abstract Tires are fabricated using single ply fiber reinforced composite materials, which consist of a set of aligned stiff fibers of steel material embedded in a softer matrix of rubber material. The main goal is to develop a mathematical model to determine the local stress and strain fields for this isotropic fiber and matrix separated by a linearly graded transition zone. This model will then yield expressions for the internal stress and strain fields surrounding a single fiber. The fields will be obtained when radial, axial, and shear loads are applied. The composite is then homogenized to determine its effective mechanical properties—elastic moduli, Poisson ratios, and shear moduli. The model allows for analysis of how composites interact in order to design composites which gain full advantage of their properties.

Reliability Simulation and Forecast Based on Virtual Prototype for the Running System of Complicated Equipments

2014 ◽  
Vol 543-547 ◽  
pp. 195-198
Author(s):  
Li Jun Cao ◽  
Hui Bin Hu ◽  
Gui Bo Yu ◽  
Shu Hai Wang
Keyword(s):  
Probability Density ◽  
Local Stress ◽  
Virtual Prototype ◽  
Probability Density Distribution ◽  
Stress And Strain ◽  
Load Spectrum ◽  
Density Distribution Function ◽  
Running System ◽  
Maintenance Cycle ◽  
Damage Theory

The running system is the key part to finish training or battle tasks of complicated equipments. But formidable working conditions influence the measurement of load spectrums and it is difficult to analyze and forecast the reliability of running system. Actual vehicle experiments and virtual prototype are firstly combined to obtain complete load spectrum of running system. According to the materials S-N curve, stress and strain spectrums can be computed. Nominal stress method and local stress and strain method are combined with probability density accumulation damage theory to compute the probability density distribution function. Then, the reliability of running system can be forecasted, which provide adequate reference for the maintenance cycle confirmation and mission reliability prediction.

scholarly journals Influence of Orthotropy on Biomechanics of Peri-Implant Bone in Complete Mandible Model with Full Dentition

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Xi Ding ◽  
Sheng-Hui Liao ◽  
Xing-Hao Zhu ◽  
Hui-Ming Wang
Keyword(s):  
Orthotropic Material ◽  
Tooth Enamel ◽  
Local Stress ◽  
Isotropic Case ◽  
Stress And Strain ◽  
Isotropic Model ◽  
Bone Interface ◽  
Multiple Data ◽  
Cad Models ◽  
The Impact

Objective.The study was to investigate the impact of orthotropic material on the biomechanics of dental implant, based on a detailed mandible with high geometric and mechanical similarity.Materials and Methods.Multiple data sources were used to elaborate detailed biological structures and implant CAD models. In addition, an extended orthotropic material assignment methodology based on harmonic fields was used to handle the alveolar ridge region to generate compatible orthotropic fields. The influence of orthotropic material was compared with the commonly used isotropic model and simplified orthotropic model.Results.The simulation results showed that the values of stress and strain on the implant-bone interface almost increased in the orthotropic model compared to the isotropic case, especially for the cancellous bone. However, the local stress concentration was more obvious in the isotropic case compared to that in orthotropic case. The simple orthotropic model revealed irregular stress and strain distribution, compared to the isotropic model and the real orthotropic model. The influence of orthotropy was little on the implant, periodontal ligament, tooth enamel, and dentin.Conclusion.The orthotropic material has significant effect on stress and strain of implant-bone interface in the mandible, compared with the isotropic simulation. Real orthotropic mechanical properties of mandible should be emphasized in biomechanical studies of dental implants.

Simulation of the Global Response of Welded Joint Using Digital Image Correlation Measurement

2013 ◽  
Vol 749 ◽  
pp. 597-600
Author(s):  
Chao He ◽  
Shi Ming Cui ◽  
Yan Zeng Wu ◽  
Ze Fu Luo ◽  
Qing Yuan Wang
Keyword(s):  
Digital Image Correlation ◽  
Tensile Test ◽  
Tensile Properties ◽  
Digital Image ◽  
Welded Joint ◽  
Pure Aluminum ◽  
Local Stress ◽  
Image Correlation ◽  
Global Response ◽  
Mechanical Heterogeneity

The effect of the mechanical heterogeneity on the global and local tensile properties of laser-arc hybrid welded joints in industrial pure aluminum has been investigated. Digital image correlation method has been used during tensile test for mapping the strain distribution and to determine the local stress-strain curves of FZ and HAZ. The tensile properties of the various regions are very heterogeneous and HAZ is the weakest region because of the strain localizes during tensile test. Finite element technique was used to model the global response of welded joint based on local constitutive properties which could be determined from DIC results.

scholarly journals Strain field evolution at the ductile-to-brittle transition: a case study on ice

Solid Earth ◽  
2017 ◽  
Vol 8 (5) ◽  
pp. 943-953 ◽  
Author(s):  
Thomas Chauve ◽  
Maurine Montagnat ◽  
Cedric Lachaud ◽  
David Georges ◽  
Pierre Vacher
Keyword(s):  
Stress Concentration ◽  
Dynamic Recrystallization ◽  
Strain Field ◽  
Crack Opening ◽  
Local Stress ◽  
Image Correlation ◽  
Brittle Transition ◽  
Field Evolution ◽  
Crack Tips ◽  
Ductile To Brittle Transition

Abstract. This paper presents, for the first time, the evolution of the local heterogeneous strain field around intra-granular cracking in polycrystalline ice, at the onset of tertiary creep. Owing to the high homologous temperature conditions and relatively low compressive stress applied, stress concentration at the crack tips is relaxed by plastic mechanisms associated with dynamic recrystallization. Strain field evolution followed by digital image correlation (DIC) directly shows the redistribution of strain during crack opening, but also the redistribution driven by crack tip plasticity mechanisms and recrystallization. Associated local changes in microstructure induce modifications of the local stress field evidenced by crack closure during deformation. At the ductile-to-brittle transition in ice, micro-cracking and dynamic recrystallization mechanisms can co-exist and interact, the later being efficient to relax stress concentration at the crack tips.

Stress-Driven Migration of Low-Angle Grain Boundaries Near Crack Tips in Nanocomposites Containing Incoherent Nanoinclusions

2018 ◽  
Vol 55 (1) ◽  
pp. 26-34
Author(s):  
S.V. Bobylev ◽  
L.-S.D. Galeeva
Keyword(s):  
Grain Boundaries ◽  
Metal Matrix ◽  
Critical Stress ◽  
Dislocation Dynamics ◽  
Metal Matrix Nanocomposites ◽  
Discrete Dislocation Dynamics ◽  
Discrete Dislocation ◽  
Growing Crack ◽  
Crack Tips ◽  
Matrix Nanocomposites

Abstract Theoretical model describing stress-driven migration of low-angle grain boundaries (GBs) in the vicinity of growing crack in metal matrix nanocomposites with reinforcing (metallic or ceramic) incoherent nanoinclusions is proposed. Using two-dimensional discrete dislocation dynamics approach profiles of migrating GBs are analytically calculated and critical stress for transition into unstable migration mode is found. It is shown that the presence of crack always promotes stress-driven migration and thus grain growth.

Evaluation of Local Stress Distribution Near Notch and Crack Tips in Al2O3 by Synchrotron Radiation

2005 ◽  
Vol 490-491 ◽  
pp. 35-40 ◽  
Author(s):  
Yoshihisa Sakaida ◽  
Yozo Sawaki ◽  
Keisuke Tanaka ◽  
Yoshiaki Akiniwa
Keyword(s):  
Synchrotron Radiation ◽  
Stress Distribution ◽  
Local Stress ◽  
Crack Tips

Short Intergranular Cracks in Elasto-Plastic Polycrystalline Aggregate

2002 ◽  
Author(s):  
Leon Cizelj ◽  
Heinz Riesch-Oppermann
Keyword(s):  
Grain Size ◽  
Stress Corrosion ◽  
Steam Generator ◽  
Local Stress ◽  
Stress Fields ◽  
Computational Algorithms ◽  
Polycrystalline Aggregate ◽  
Intergranular Stress Corrosion ◽  
Crack Tips ◽  
Steam Generator Tubes

Computational algorithms aiming at modeling and visualization of the initiation and growth of intergranular stress corrosion cracks (e.g., in the steam generator tubes) on the grain-size scale have already been proposed. Main focus of the paper addresses the influence of randomly oriented anisotropic elasto-plastic grains on the microscopic stress fields at crack tips. The limited number of calculations indicate that the incompatibility strains, which develop along the boundaries of randomly oriented grains, influence the local stress fields (J-integrals) at crack tips significantly.

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