随机荷载作用下疲劳裂纹扩展新算法

Novel Arithmetic of Fatigue Crack Growth under Random Loading

认为疲劳裂纹扩展的机理是惯性效应,并在断裂力学的基础上,通过引入惯性效应因子导出等幅荷载作用下疲劳裂纹扩展速率解析表达式。将随机载荷用通用的傅立叶变换转换为等幅非对称循环载荷的叠加,这一方法具有力学概念清晰、简便的特点。通过与试验数据和其它方法的对比研究,证明了该方法的有效性。成功地将等幅载荷作用下疲劳裂纹扩展新公式推广到随机载荷作用。

According to the basic mechanics theory,the mechanism of fatigue crack growth is an inertial effect,and A formula of the fatigue crack growth rate under constant amplitude loading by importing an inertia effect coefficient on the basis of fracture mechanics is analytically deduced.Based on above research,the random loading spectrum is converted into the superposition of a series of asymmetrical cyclic constant amplitude loads by applying Fourier transformation.This method has clear mechanical concepts and concise expressions.Several cases of fatigue crack growth life tests under random loading are predicted by this method.As a result,the predictions are in good agreement with the test data.At the same time,this method is also proved to be effective by comparing with other methods.The novel formula of fatigue crack growth under constant amplitude loading is such generalized to the case under random loading.