基于临界面的多轴振动疲劳寿命预测

目的提出一种新的基于临界面正应力的高周多轴疲劳寿命预测方法。方法通过对主应力进行投影,得到各时刻下临界平面内的应力大小,利用雨流法计算不同临界面下的疲劳损伤,并通过权函数,得到主应力的角度期望值,进而预测结构的疲劳寿命。结果通过试验件进行仿真模拟,对底端作用两个方向PSD频率范围为8～200 Hz,大小为0.006、0.003、0.008 g~2/Hz的强制加速度激励得到多轴应力响应,以此计算4种工况下的随机加速度振动疲劳试验预测寿命,对比试验寿命误差基本处于2倍界以内。结论新的基于临界面正应力的疲劳寿命预测方法能有效预测多轴振动疲劳寿命。

Multi-axis Vibration Fatigue Life Prediction Based on Critical Plane

The work aims to propose a new high cycle multi-axis fatigue life prediction method based on critical plane normal stress. By projecting the principal stress, the stress in the critical plane at each moment was obtained, and the fatigue damage under different critical planes was calculated by rain flow method. Then, the angular expected value of the principal stress was obtained through weight function to predict the fatigue life of the structure. Through the simulation of the test specimen, the forced acceleration excitation with PSD frequency range of 8~200 Hz in two directions and value of 0.006, 0.003, 0.008 g2/Hz, was applied to the bottom to obtain the multi-axis stress response, so as to calculate the predicted life of the random acceleration vibration fatigue test under four working conditions. Through comparison, the test life error was basically within the bounds of 2 times. The new fatigue life prediction method based on the critical plane normal stress can effectively predict the fatigue life of multi-axis vibration.