Simplification of the Delany–Bazley approach for modelling the acoustic properties of a poroelastic foam

The acoustic performance of mufflers is often enhanced by the inclusion of dissipative materials. A simplified implementation of the Delany–Bazley method is presented which facilitates the acoustic characterisation of poroelastic foam in computational models in the absence of material airflow resistivity data. The acoustic characteristics of a polyurethane foam material were experimentally obtained using a two-cavity impedance tube method. A finite element model of an expansion chamber design incorporating foam is presented. Numerical results of the transmission loss for the foam-filled muffler are compared with results obtained experimentally using a two-microphone acoustic pulse method.