非比例载荷下304不锈钢低周疲劳寿命预测

在拉扭疲劳试验机上完成了一系列非比例加载下对304不锈钢的低周疲劳试验，对目前常用的几种多轴疲劳寿命预测模型进行了分析比较。结果表明，以单轴疲劳寿命分析方法为基础的等效应变法，不能预测多轴非比例加载下的低周疲劳寿命，以临界面法为基础的Socie剪切模型对非比例加载下304不锈钢材料的疲劳寿命预测较好。

LOW CYCLE FATIGUE LIFE PREDICTION FOR 304 STAINLESS STEEL UNDER NONPROPORTIONAL LOADINGS

A series of experiments on low cycle fatigue under nonproportional loading were conducted on tension torsional fatigue facility for 304 stainless steel. Several multiaxial fatigue criteria in common use were analyzed. It shows that equivalent strain approaches based on uniaxial fatigue life analysis methods like maximum shear strain parameter and maximum normal strain parameter couldn't predict low cycle fatigue lives under nonproportional cyclic loadin. Because of not considering of deformation behavior under nonproportional loading, the unconservative predictions of the factor of five times are given. The predictions of SWT model based on tensile critical plane are generally within a factor of two scatter band, but some test points are on unsafe side. The Socie shear model based on critical plane approach gives better prediction when it is used to predict fatigue lives of 304 stainless steel under nonproportional loading. The predictions of Fatemi model based on shear critical plane approach are on conservative side.