Nonlinear Random Response of Composite Panels in an Elevated Thermal Environment

摘要

Sonic fatigue is being considered as one of the major design parameters for the new generation of high-speed flight vehicles. Efficient and accurate analysis methods for predicting nonlinear random response and estimating fatigue life of surface panels are urgently needed. A brief review of the various analysis methods for nonlinear random vibrations of aircraft surface panels is given. An efficient element finite modal formulation is presented for the prediction of panel response at high sound pressure levels and elevated temperatures. Band-limited Gaussian white noise is generated as input excitation.. Numerical results were compared with linear analytical and Fokker- Planck-Kolmogorov equation solutions for validation of the present method. Number of modes, mesh size, and integration time steps for accurate and converged response predictions were also presented. Examples are given for a simply supposed isotropic and a clamped composite panel at various combinations of sound pressure level and temperature. Numerical results include time- histories, root mean square values of maximum deflection and strain, probability distribution functions, power spectrum densities (PSD), and higher statistical moments of maximum deflection and strain. The PSD can be used for fatigue life estimation.