Nonlinear sound absorption of ultralight hybrid-cored sandwich panels

A combined experimental, numerical and analytical approach is employed to investigate the nonlinear effect of incident sound pressure level (SPL) on the sound absorption performance of a novel ultralight sandwich panel with perforated honeycomb-corrugation hybrid (PHCH) core. Built upon the motion, continuity and heat conduction equations for compressible viscous fluids, the numerical model fully considers the nonlinear effects caused by incident sound wave with high SPL. The analytical model is constructed by using an approximation solution to the characteristic impedance of micro-perforated panel (MPP) absorbers with consideration of the compressibility of the fluid inside the perforation. The validity of both the numerical and analytical models is checked against experimental measurement results. The effects of facesheet thickness, corrugation thickness and core height on sound absorption are systematically explored. The proposed PHCH sandwich construction is ultralight. It has small total thickness and possess simultaneous load-bearing, energy absorption and sound absorption properties, showing great potential in multi-functional applications. This work provides a nonlinear analytical model and a nonlinear numerical method for the sound absorption of the ultralight hybrid-cored sandwich structures, which demonstrates their superior performance against sound with high SPL.