残余应力场中疲劳裂纹闭合模型的扩充

A Reformed Model for Fatigue Crack Closure with in the Residual Stress Field

在残余应力场中一般采用残余应力强度因子法预测疲劳裂纹的扩展,但它未考虑残余压应力对裂纹的闭合效应。本文以八十年代初J、C、Newman提出的疲劳裂纹闭合模型为基础,加以修正和扩充使之适用于单边裂纹体,并在原有模型的裂纹面接触应力上迭加残余应力参量。通过实验测定了40Cr钢高温回火态试样在有和无残余应力场时的裂纹闭合力和扩展速率,结果表明,计算值与实验值基本一致。扩充模型尚存在些问题有待改进。

The residual stress intensity factor is usually employed to examine the crack growth rate within the residual stress field,but the closure effect which plays an important role is not considered. This paper intends to reform the crack closure model which was originally suggested by J.C. Newman in early 1980’s in order to meet the needs of single edge cracked body and cause the residual stress to be superimposed on the contact stress for crack growth pred-iction. A high temperature medium carbon steel is applied. The crack closure force and the growth rate were measured. The experiment data of the closure force and growth rate with and without residual stress considerably agree with the calculated results.