基于损伤等效的振动疲劳试验载荷转换

Load Conversion of Vibration Fatigue Test Based on Damage Equivalence

目的使用简谐激励替代随机平直谱激励进行振动疲劳试验。方法利用有限元仿真计算某典型铝合金试验件在简谐激励和随机平直谱激励下的疲劳寿命,分析2种工况下试验件寿命相等时激励的等效关系。进行一组定频激励试验和一组谱激励试验,对比试验结果,验证在某典型铝合金试验件上利用简谐激励替代随机平直谱激励进行振动疲劳试验的可行性。结果通过试验与仿真技术,对2024-T4铝合金试验件在一定频率非共振简谐激励和随机平直谱激励作用下的振动疲劳寿命规律进行研究,得出了不同激励作用下试验件寿命相同时载荷的等效关系。结论基于损伤等效,工程中可以使用简谐激励代替随机平直谱激励进行振动疲劳试验,从而解决了一类振动疲劳试验加载困难的问题,实现振动疲劳的试验加速。

The purpose of this paper is to use simple harmonic excitation instead of random flat spectrum excitation to carry out vibration fatigue test.This paper calculates the fatigue life of a typical aluminum alloy test piece under simple harmonic ex-citation and random flat spectrum excitation by finite element simulation,and analyzes the equivalent relationship of the two kinds of excitation when the life of the test piece is equal under the two working conditions.Then the paper carries out a set of constant frequency excitation tests and a set of spectral excitation tests to verify the feasibility of using simple harmonic excita-tion instead of random flat spectral excitation to carry out vibration fatigue test on a typical aluminum alloy test piece by com-paring the test results.Through the study of the vibration fatigue life law of 2024-t4 aluminum alloy test piece under certain frequency non-resonant simple harmonic excitation and random straight spectrum excitation with test and simulation technol-ogy,this paper obtains the equivalent relationship of load when the test piece has the same life under different excitation.Based on damage equivalence,simple harmonic excitation can be used to replace random straight spectrum excitation in vibration fa-tigue test in engineering,so as to solve the problem of difficult loading of a kind of vibration fatigue test and realize the accel-eration of vibration fatigue test.