Vibration Fatigue Analysis for Structural Durability Evaluation Under Vibratory Loads

The structural integrity of aircraft structures under vibratory loads is primarily evaluated through vibration tests, but it is necessary to predict the design life through vibration fatigue analysis at the design stage. Vibratory loads affect the durability of aircrafts by combining with the dynamic characteristics of their structures. The generation of stress spectrum in the vibratory loads, which must be calculated from power spectral density, is different from the calculations in the time domain. In this study, the stress spectrum generation and fatigue life were analyzed for various frequency bands with different characteristics. Through comparison of the fatigue life in the frequency domain and time domain, the characteristics of the stress spectrum estimation and optimal calculation methods are presented. It was confirmed that the frequency domain results tend to be more conservative in most cases than the time domain results, and Dirlik’s procedure estimates accurately in all frequency bands. A simple correction of the Narrow-band and Steinberg results could increase the accuracy of the fatigue life prediction.