一种基于临界平面法的多轴疲劳寿命预测模型

在多轴交变应力作用下，由于非比例循环附加强化效应导致疲劳寿命降低。针对这一问题，以薄壁圆管疲劳试件为研究对象，在分析临界平面上剪应变和正应变随相位角变化特征的基础上，引入了一个新的有效循环变量———临界平面上的等效应力，提出了一种新的多轴疲劳预测模型。新的损伤参量不含经验常数，便于工程实际的运用。通过和铝合金7075-T651多轴疲劳实验数据比较，结果表明，所提出的多轴寿命预测模型具有更好的预测精度，适用于比例与非比例加载条件。

Multiaxial Fatigue Life Prediction Model Based on Critical Plane Approach

The cyclic hardening by non-proportional loading will reduce the fatigue life under multiaxial cyclic stress.In order to solve this problem,a new damage parameter for multi-axial fatigue was proposed by introducing a new effective loop variable-the equivalent stress of the critical plane,based on the analysis for the state of the shear strain and strain changing with phase angle characteristics on the critical plane of the thin-walled cylindrical specimen. It is convenient for engineering application because of its non-material constants in this parameter.Compared with the data from aluminum alloy 7075-T65 1 multiaxial fatigue experiment,the results show that multiaxial life prediction model has better prediction precision,suitable for proportional and non-proportional loading conditions.