Acoustic fatigue and dynamic behavior of composite panels under acoustic excitation

Abstract

Composite panels in aircraft structures are exposed to fluctuating sound pressure originating mostly from engine noise and air flow. In this paper, acoustic fatigue and dynamic response of composite panels under acoustic excitation are investigated numerically. Composite panel is simulated with finite element analysis. The panel is considered clamped at one edge, whereas the opposite edge is assumed to be free. The panel is subjected to random repeated loading generated by sound waves. The analysis estimates probabilistic amplitude frequency response to acoustic loading and natural frequencies of the panel. Maximum random vibration amplitude and the corresponding natural frequency are used for the fatigue life calculation. Critical element identification of the model regarding response is a major approach as part of this work performed to predict the element with maximum probabilistic response, i.e. root mean square strain. This allows fast and accurate result for the models with high number of elements by identifying root mean square strain at the most critical element on the panel without requiring the post-analysis for each element. At the end of this study, the results of finite element analysis and the effect of acoustic loading and critical element selection on fatigue life of the composite panels are presented.