Acoustic fatigue life prediction of structure based on power spectral density method

Abstract

In the field of aerospace engineering, a large amount of thin shell structure is used in order to reduce the weight. These structures will be damaged by acoustic fatigue at high levels of noise and vibration loads. Acoustic fatigue analysis of thin walled structure is a very important part of the aircraft structure design. Simulation and analysis of three different fixation methods for random acoustic loads of thin-walled structure of aluminium alloy were introduced in this article. A method of power spectral density (PSD) was calculated for sound pressure level respectively in the band limited white noise 145 dB, 148 dB, 151 dB combined with fatigue damage theory based on linear length of the sound. The length of the 7075 Aluminium alloy material is 300 mm, and the thickness is 1.5 mm. The results show that: in the case of different ways of holding, the maximum stress suffered by the aluminium alloy thin sheet appeared at the constraint location, and this position is dangerous position for structural fatigue where will first be destroyed by random loads. Under random acoustic loads, the strain cloud of aluminium alloy thin sheet structure is the same with the first vibration mode, so the random vibration response was most effected by the first modal. Acoustic fatigue of the different sound pressure level was calculated by using the method of PSD and Miner linear damage rule.