低循环疲劳寿命预测的幂指函数模型

从塑性应变幅与疲劳失效反向数在双对数坐标系下的二次曲线特征及残差稳定化两个角度出发，基于幂变换法，构造低周疲劳寿命预测的幂指函数模型。给出一些材料的幂变换指数p值，并对模型寿命预测能力进行检验，结果表明，幂指函数模型对低周疲劳寿命预测具有良好的精度。并指出Manson-Coffin方程实际是幂指函数模型在双对数坐标系下的一阶线性近似，它对应于p=1的情况。由于幂指函数模型非线性的增强，使其对寿命的预测能力大大提高，而通过幂变换方法，模型参数回归仍采用线性回归方法，保持了模型应用的简便性。

LOW CYCLE FATIGUE LIFE PREDICTION METHOD BASED ON POWER-EXPONENT FUNCTION MODEL

The analysis took two points into account,namely quadratic characters of plastic strain amplitude vs.reversals to failure in log-log scale coordinates and the residual stabilization.Based on power transformation methods,it advanced a power-exponent function model for LCF(low cycle fatigue) life prediction.The investigation gave some power transformation exponents (p) and model performances contrast results of some materials.The contrast results show that power-exponent function model has better performances and precisions for LCF life prediction.In fact,Manson-Coffin equation is the first order Taylor expansion approximation of power-exponent function model in log-log scale coordinates and is the equivalence form when p is equal to 1.The enhancement of nonlinearity makes the power-exponent function model present better precision.The new life prediction model remains the simpleness for engineering application that the model parameter estimation still use linear regression method.