The effect of leakage on the sound absorption of a nonlinear perforated panel backed by a cavity

This study investigates the sound absorption of a nonlinear perforated panel backed by a cavity with leaking edges. Many other related works assume that the cavity is perfectly enclosed. This is the first study to address the effect of leakage on the sound absorption of a nonlinear perforated panel. The development of the absorption formula is based on the classical nonlinear thin plate theory, the threedimensional wave equation and micro-perforation acoustic impedance. The recently developed multilevel residue harmonic balance method is introduced to compute the nonlinear vibration responses. Unlike previous harmonic balance methods, the proposed method generates nonlinear algebraic equations in the process of computing zero-level solutions only, and produces linear algebraic equations in the higher-level processes. The theoretical results obtained from the proposed method and the numerical integration method are in reasonable agreement. The effects of various parameters such as the excitation magnitude, damping ratio, cavity depth, perforation ratio and amount of leakage are examined. (C) 2016 Elsevier Ltd. All rights reserved.