短周期谱载荷作用下的疲劳裂纹扩展估算

THE PREDICTION OF FATIGUE CRACK GROWTH UNDER SHORT PERIOD SPECTRUM LOADIND

<正> 本文公式系由线性累积损伤寿命公式乘以一个考虑超载迟滞效应的修正系数而构成的。 1.公式推导 Walker裂纹扩展方程为 da/dN=c(ZK_(max))~n (1)式中c,n,q及u为材料常数;R为应力比。 应力强度因子可以表示成式中,σ_(max)为垂直于裂纹的外加毛应力;Y为构型系数,它与裂纹长度有关。 当考虑超载迟滞效应时。

A semilinear formula in consideration of overload retardation effect is derived from Wheeler's retardation model for the-prediction of fatigue crack growth under short period flight-by-flight or block spectrum loading. As long as the spectrum size is small enough,the result calculated by this formula will closely agree with one of Wheeler's cycle-by-cycle integration.