一种新的随机疲劳寿命预测方法

New Prediction Method of Fatigue Life Under Random Loading

根据疲劳损伤具有局部性的特点，在应力场强法的基础上，提出了缺口疲劳损伤局部应力应变场理论；该理论可同时考虑缺口根部局部应力应变梯度对疲劳损伤的影响．通过对缺口件进行随机交变加载下的弹塑性有限元分析，提出一种随机加载疲劳寿命预测的局部应力应变场强法；由该法来预测缺口件疲劳裂纹形成寿命，其精度要好于传统的局部应力应变法．

According to the characteristic that fatigue damage is partial, on the basis of the stress field intensity method, a theory of local stress-strain field for fatigue damage at notch is presented in this paper, which considers the effects of the local stress-strain' s gradient on fatigue damage. Through the finte element analysis on the elastoplasticity of notched specimen under the random alternate loading, a local stress-strain field intensity method is proposed for prediction of fatigue life under random loading. Using this method to predict the life of fatigue crack initiation has obtained better precision than the traditional local stress-strain method.