缺口件两轴循环弹塑性有限元分析及寿命预测

利用弹塑性有限元模拟,对高温两轴比例与非比例拉扭应变循环加载下的光滑薄壁管件与缺口轴类件进行研究.材料弹塑性特性用Von Mises屈服准则、多线性运动硬化准则和高温单轴循环加载的应力应变数据来描述.采用柱坐标系下在试样一端加轴向和周向位移来实现拉扭应变加载.对光滑薄壁管件的后处理结果与试验结果比较,证实了这种方法的正确性和可用性,进而应用到缺口件,得到缺口根部局部的循环应力应变响应.基于有限元数据,采用Kandil-Brown-Miller法和Smith-Watson-Topper法预测了缺口件疲劳裂纹萌生寿命.

Elastoplastic Finite Element Analysis and Fatigue Life Prediction for Notched Specimens under Biaxial Cyclic Loading

An elastoplastic finite element analysis is adopted for thin tubular and notched specimens under biaxial proportional and nonproportional tension-torsion loading at high temperature. Elastoplastic material property is described by the Von Mises yield criterion, the multilinear kinematic hardening rule and uniaxial cyclic stress-strain data under high temperature. Tension-torsion loading with strain controlling is carried out by applying the axial and circular displacement on one end of the specimen in the cylindrical coordinate system. The method is proved suitable by comparison between FEA and experimental results. Then the elastoplastic finite element method is used to the notched specimens. The local cyclic stress-strain responses at notch root are obtained. Fatigue crack initiation life is predicted on the basis of the local stress-strain data with Kandil-Brown-Miller and Smith-Watson-Topper models.