Nonlinear random response and fatigue life estimation of curved panels to non-uniform temperature field and acoustic loadings

Abstract

Nonlinear random response and fatigue life estimation of the skin panels of hypersonic flight vehicles at elevated temperatures and high intensity acoustic loadings have become a matter of considerable importance in recent years. Finite element equations are presented for the prediction of nonlinear responses of curved panels under combined thermo-acoustic loadings. Thermal loading with a non-uniform temperature field is considered, and band limited Gaussian white noise is chosen as random acoustic loading. A numerical integration is applied to determine random response. Thermal buckling temperature and thermal buckling deflections are obtained to explain the snap-through phenomenon. The modal frequency of the vibration about the thermally buckled equilibrium position is studied, which shows great difference between the primary and secondary buckled equilibrium position of curved panels. Displacement and stress response obtained show nonlinear characteristics of curved panels under thermo-acoustic loadings. Stress-life (S-N) curves and rainflow counting method are combined by means of damage accumulation theory and mean stress model to predict curved panel fatigue life. The results show that the fatigue life estimation of the curved panel by using the Smith-Watson-Topper model is more conservative.