复杂载荷历程下局部应力—应变响应模拟及循环计数方法研究

用局部应力—应变法预测疲劳寿命的关键是危险点局部应力—应变响应的确定和循环计数。工程上常用Neuber法或修正Neuber法近似计算局部应力—应变响应。本文对Neuber法进行了改进,改进后的方法避免了对每一名义应力变程都需要建立新的坐标原点和解非线性方程组的繁琐计算,能够保证足够精度,程序简单,计算速度快,尤其适合大样本复杂载荷历程下的疲劳寿命预测。

Investigation on the Methods of Modeling Local Stress-Strain Responses and Cycle Counting under Complex Load Histories

The key points for predicting fatigue life vising local stress-strain method are the determination of local stress-strain responses and cycle counting in dangerous area. In engineering, the Neuber Method and the Revised Neuber Method are widely used to determine local stress-strain response. In this paper, the Neuber Method is improved according to the need in practice. The improved method can avoid the tedious calculation of establishing new coordinate origin and resolving nonlinear equations to each nominal stress reversal. It possesses many advantages such as high accuracy, simple computer program and less calculatio expenses. The improved method is particularly suitable for the prediction of fatigue life under long complex load histories.