考虑材料循环塑性的疲劳裂纹扩展模拟

提出了一种考虑材料循环塑性性能的研究疲劳裂纹扩展与闭合行为的有限元模拟方法．对所选用的循环塑性本构关系进行了基本实验检验．探讨了在疲劳裂纹扩展有限元分析中网格尺寸的影响，给出了网格优化准则．研究了在循环硬化条件下考虑裂纹合效应时裂纹面张开廓形、裂纹尖端应力、应变场和正反向塑性区的演变规律．对于循环硬化和不同循环应力比Ｒ等因素对裂纹张开应力水平的影响也作了考察

NUMERICAL MODELING OF FATIGUE CRACK GROWTH WITH CYCLIC HARDENING OF MATERIAIS

A method of finite element modeling of fatigue crack growth and closu re behavior is presented. The cyclic plastic hardening behavior of materials is taken into account. The chosen cyclic plasticity constitutive model has been exa min ed. After a discussion about the influence of finite element mesh on the numerical results, a mesh optimization criterion is suggested. Employing the suggested mumerical method and considering the crack closure effect, we investigate the evolution of the profile of crack surfaces, the stress and strain fields ahead of the crack tip and the forward and reversed plastic zones. The influence of cyclic hardening and stress ratio on the crack opening stress level is discussed as well.