块谱特征与疲劳裂纹随机扩展

Load Spectrum Features and Fatigue Crack Random Propagation

目前的疲劳裂纹随机扩展模型大多建立在损伤逐步累积的基础上，其数学描述繁琐复杂，计算用时较多。本文较为深入地研究了载荷分散性对裂纹随机扩展的影响，定义了块谱强度Ｓｅｑ和形状因子α，并用这些特征去描述载荷分散性对裂纹随机扩展的影响，结果表明裂纹随机扩展的均值可以用块谱强度Ｓｅｑ恰当地描述，而块谱的形状因子α可以很好地反映裂纹随机扩展的方差，因此通过块谱的特征迅速获取裂纹随机扩展的参数是可行的。

At present, most of the accepted stochastic models of fatigue crack growth are set up bassed on the accumulation of fatigue damage, which usually needs a lot of computation and uses complex mathematical expressions to describe the propagation behaviours. In this paper two spectrum features, average strength S eq and shape factor α, are defined to discribe the statistic behaviours of fatigue crack growth. Numerical results show that load spectrum average strength S eq can discribe the mean of fatigue crack size, and the spectrum shape factor α is closely related to the variance of fatigue crack size.