循环压载下缺口旁疲劳裂纹扩展

对承受循环压载的缺口试件的疲劳问题进行了试验和理论研究。结果表明，疲劳裂纹是在残余拉应力和循环压应力作用下萌生和扩展的，压塑性变形是裂纹萌生和扩展和扩展的必要条件。循环压载下仍存在着裂纹张开和裂纹闭合，其机理与拉伸循环下不同。以试验中采用的ＬＹ１２ＣＡ材料边缺口试件为例，提出了考虑裂纹闭合效应的扩展率计算模型，结果与试验吻合得较好。

FATIGUE CRACK PROPAGATION OF THE NOTCHED SPECIMENS UNDER CYCLIC COMPRESSIVE LOADING

This paper attempts to do some experimental and theoretical researches on fatigue of the notched specimens under cyclic compressive loading.The result shows: the local residual tensile stress and cyclic compressive loading thrust fatigue crack initiation and propagation in the size of compressive plastic zone.Crack opening and crack closure can still exist under cyclic compressive loading, whose mechanism differs from that under cyclic thrust loading.As a sample,the LY12CZ material and the notched specimens adopted in the experiment, this paper presents a calculation model of crack propagation rate of crack closure under cyclic compressive loading,which agrees well with the results of the experiment.Hence,this research manifests:the view that crack can propagate only under the condition of opening can be applicable to compressive fatigue as well.