Research On Nonlinear Response Characteristics Of Composite Thin-walled Structure Subjected To Thermo-acoustic Loading

The advances in propulsion systems,aerodynamics and flight control designs have allowed flight vehicles to technically operate at hypersonic speeds.C/C composites are extensively used in modern hypersonic research and reusable vehicles.This is due to their good strength retention at high temperatures and lightweight capability for aero structure integration.The response of surface panels exposed to severe aerodynamic,thermal and acoustic environment is often nonlinear.In this paper,both theoretical analysis and numerical simulation are proceeded with the aim of revealing the influence of thermo-acoustic loads on the nonlinear response of composite thin-walled structures.Firstly,the nonlinear time domain Monte Carlo methods can be extended to dynamic studies of multilayered structures,the nonlinear large deflection governing equation of thin-walled structures under thermo-acoustic loadings is founded.A finite element model for analyzing nonlinear random dynamic behaviors of Carbon-Carbon composite panels under thermo-acoustic excitation is also founded.Secondly,the critical thermal buckling temperatures and modal frequencies of simply-supported composite panel under thermal loads are calculated.A time domain study of the random response of a composite laminated plate under combined high intensity acoustic and thermal loading is presented.Analyze nonlinear random dynamic behaviors of Carbon-Carbon composite panels under time-varying acoustic excitation,and nonlinear random dynamic behaviors of Carbon-Carbon composite panels with temperature gradients under Guassian sound excitation.The temperature distribution over the plate is generalized to include thermal gradients in the surface.The acoustic load is normal incidence.Numerical results include root mean square(RMS)values of maximum deflections,time histories and power spectrum densities(PSD)of the deflection response.The characteristics of nonlinear thermo-acoustic response are investigated in detail.Finally,the results obtained in this paper can contribute greatly to the thorough understanding of thermo-acoustic response of composite thin-walled structures.