NONLINEAR-WAVE PROPAGATION THROUGH RIGID POROUS MATERIALS .2. APPROXIMATE ANALYTICAL SOLUTIONS

A wave perturbation method of analyzing the internal propagation and surface admittance characteristic of highly porous acoustic materials with rigid frames at high particle velocities is presented. It is an iterative method whose implementation is based on experimental observations. Numerical results for an open-cell foam material are compared with both experiments and exact numerical solutions of the fundamental equations of nonlinear motion. Most of the salient features of the surface admittance of a bulk material are predicted analytically with the accuracy increasing as the frequency of excitation is increased. The method is restricted to pure-tone excitation. © 1990, Acoustical Society of America. All rights reserved.