Predicting Fatigue Life of a mount of a Device with Shock Absorber

Abstract

All aircraft operate under vibration loads and these loads cause vibration-induced fatigue damage to the parts. Fatigue damages are dangerous because they occur suddenly without giving a warning before, for this reason they need to be carefully analyzed. In the analysis, especially the natural frequencies and dampings must be determined correctly, because when the vibration loads match with the natural frequencies, resonance is observed and this reduces the life of the part. In this thesis, the fatigue life of a mount of device with shock absorber is investigated. Flight tests were carried out in real flight scenarios to provide an input for the analysis. A modal test was performed to model the shock absorbers correctly. Vibration test was performed to prove the accuracy of the prepared finite element model and to determine the damping ratios. Fatigue analyses were performed in frequency domain with a commercial software, nCode, and the accuracy of the analysis was proven by the test.