拉伸过载对裂纹张开应力影响的量化分析

摘要

To obtain crack opening stress (σop ) under tensile overloading quickly, an approach was proposed to de-termineσop based on the variable quantity of maximum crack opening displacement ( VMCOD) .On the basis of e-lastic-plastic finite element analysis, the functional relationship betweenσop and VMCOD of a center-cracked speci-men was established to determine the effects of stress ratio, overload ratio, and material properties.The relationship was applicable for determiningσop of metallic hardening materials under multiple overloads.For the intermittent o-verload, the effect of distance between overloads on crack propagation was investigated.Results show that the maxi-mum retardation occurred when the distance between overloads was 0.233 times that of the high-load plastic zone. Thus, the proposed approach was an effective scheme for obtaining optimum retardation.%为快速地估算拉伸过载作用下裂纹张开应力,本文提出基于裂纹最大张口位移变化量来计算裂纹张开应力方法.针对单次过载、多次连续过载,考虑了过载比、应力比、材料特性的影响,通过弹塑性有限元分析建立中心穿透裂纹张开应力与最大张口位移变化量的函数关系,该函数关系适用于不同形式的连续拉伸过载的硬化金属材料;对于间断过载,量化分析了过载距离对裂纹扩展的影响,发现当过载距离等于0.233倍,高载塑性区时迟滞效应最强,为获得最佳迟滞效果提供了有效的施加方案.