一种多轴向随机激励下结构疲劳寿命分析方法

提出了一种多轴向随机激励下结构疲劳寿命估计的频域分析方法。首先，对结构进行频响分析，得到在基础加速度激励下的应力频响函数矩阵，通过随机振动分析，得到结构应力的功率谱密度矩阵；其次，采用等效的Von Mises应力功率谱密度将多轴应力问题转化为单轴应力问题；最后，利用单轴应力疲劳寿命估计的频域分析方法对结构疲劳寿命进行估计。对一典型构件在多轴向随机激励下的疲劳寿命进行了计算,并与实验结果进行了对比。另外，对构件在多轴向同时激励与单轴分别激励的疲劳损伤结果进行了对比分析，表明多轴向同时振动具有明显的多轴效应，因此进行多轴向振动疲劳研究十分必要。

A Vibration fatigue life prediction method of the structure under multi-axial random excitation

A frequency domain method for fatigue life prediction of the structure under multi-axial random excitation is presented. Fristly, the matrix of the transfer function from excitation acceleration to the response stresses is obtained through frequency response analysis. According to the random vibration theory, the PSD matrix of stress response is calculated. Secondly, the multi-axial stress problem is translated to the uniaxial stress problem via equivalent Von Mises stress PSD. Finally, the uniaxial frequency domain fatigue analysis is used for the fatigue life prediction. The fatigue life of a typical component under the multi-axial random excitation is calculated and compared with the test result . In addition, the fatigue damages of the component caused by the simultaneous multi-axial and uniaxial excitation are analyzed and compared and the multi-axial effect is also analyzed. The result shows the necessity of simultaneous multi-axial fatigue research.