Nonlinear random responses and fatigue prediction of elastically restrained laminated composite panels in thermo-acoustic environments

This paper presents a formulation for predicting the nonlinear random response of the elastically restrained laminated composite panel subjected to thermo-acoustic loads. Based on the laminated plate theory and Von Karman large deflection and classical thin plate theories, the natural characteristics are obtained via Rayleigh-Ritz method and then the governing equations of the panel subjected to combined acoustic and thermal loads are formulated. The nonlinear partial differential equations of motion are transformed to a set of coupled nonlinear ordinary differential equations in truncated modal coordinates. A numerical example where the acoustic load is considered as the Gaussian band-limited white noise is given to perform the process of obtaining the mode and responses of the panel. Taking the natural frequency obtained from the finite element method as a reference value, the process of obtaining the natural frequencies is validated by comparing the frequency results. Numerical results show that the buckling, snap-through, and nonlinear random vibrations of the thermal-elastic restrained panel can be predicted accurately. Comparing stress PSD distributions with fatigue damage distributions, the first-order mode is proved to be valid for determining the most dangerous area for fatigue life prediction.