断裂相场在循环塑性与疲劳分析中的应用  

Phase Field Approach to Cyclic Plasticity and Fatigue Analysis

作　　者：孟莉[1] 杨硕[1] 沈泳星 Li Meng;Shuo Yang;Yongxing Shen(University of Michigan-Shanghai Jiao Tong University Joint Institute,Shanghai Jiao Tong University,Shanghai,200240;Shanghai Key Laboratory of Digital Operation and Maintenance of Public Buildings and Infrastructure,Shanghai,200240)

机构地区：[1]上海交通大学密西根学院,上海200240 [2]上海市公共建筑和基础设施数字化运维重点实验室,上海200240

出　　处：《固体力学学报》2021年第3期334-344,共11页Chinese Journal of Solid Mechanics

基　　金：国家自然科学基金项目(12002205)资助。

摘　　要：断裂是结构失效的常见方式.论文在断裂相场模型的基础上应用疲劳退化函数,将断裂相场模型拓展到非线性等向强化本构的循环塑性加载.通过自编循环塑性本构与疲劳塑性相场MATLAB程序,实现了韧性断裂相场模型在疲劳裂纹扩展分析中的应用.运用此程序,分析了疲劳退化函数中的参数和缺口尺寸对疲劳裂纹扩展的影响.首先,研究发现疲劳退化函数参数与裂纹扩展速度具有正相关性.其次,通过分析研究裂纹扩展过程中的力-位移迟滞回线,发现随着裂纹的扩展,结构的刚度逐渐变小.同时,探讨了缺口尺寸对疲劳裂纹扩展的影响,研究发现缺口半径大的模型中,裂纹扩展更加迅速.本研究为相场模型在循环塑性领域的应用提供了强有力的工具.Metals play an important role in the fields of aerospace,ship,ocean and automobiles.For such materials,cracking and fracture is a common failure mode.Therefore,the study of crack initiation,propagation and structural damage is significant to metal applications.In this paper,a plastic fatigue model is built by extending the phase field approach to fracture to cyclic plasticity with nonlinear isotropic hardening.In this model,the fatigue behavior is described by a fatigue degradation function.This degradation function acts as a fatigue constitutive relation and only takes the fatigue history variable as argument.The ductile fracture analysis on fatigue crack propagation using the proposed model is realized via an in-house MATLAB program,which combines the phase field method with cyclic plasticity and fatigue degradation.The staggered iteration scheme is used to solve the primary unknowns:the displacement field and the phase field.Tension-compression asymmetry is implemented to prevent unphysical cracking due to compression.The plastic constitutive behavior is updated with a return-mapping algorithm.To save computational cost,adaptive load stepping is embedded into the program.With this model,the effects of fatigue degradation function and crack tip geometry on the crack propagation rate are analyzed.Meanwhile,the influences of fatigue history variable and size of notch on crack growth and cyclic plasticity are discussed.First,it is found that the parameters of fatigue degradation are strongly correlated with the crack propagation rate.Then,from the hysteresis loops of the force-displacement curve,it is found that crack propagation gradually decreases the stiffness of structure as expected.Last,the results reveal that under the same loading mode,crack propagates faster with a larger notch radius.It is believed that the model in this work is a useful tool for investigating cyclic plasticity,in that it provides an effective way for studying the crack propagation under various modes of cyclic load and exploring the cra

关 键 词：循环塑性 疲劳 断裂相场 退化函数 

分 类 号：TG115[金属学及工艺—物理冶金] O346[金属学及工艺—金属学]