Modal density and mode counts of sandwich panels in thermal environments

A theoretical model for calculating the modal density and mode counts of sandwich panels with composite face sheets in thermal environments is presented. Governing equations are derived by applying the Hamilton's principle based on an improved ordinary sandwich panel theory. Modal density and mode counts are calculated using the wavenumber space integration with simply supported and clamped boundary conditions taken into consideration. The accuracy of the proposed model is verified by the finite element model. Thermal effects of both thermal stresses and temperature-dependent material properties on modal density and mode counts are investigated for an aluminum honeycomb sandwich panel with simply supported and clamped boundary conditions. Results indicate that the modal density and mode counts increase with the increment of the temperature. Both of the two effects should be considered in the calculation of the modal density and mode counts of sandwich panels in thermal environments. The proposed model has a wider application scope and can contribute to the prediction of vibration response of sandwich panels in the high frequency range.