An Equivalent-Acoustic Finite Element Method for Modeling Sound Absorbing Materials in the Automobile Passenger Compartment

Abstract

An equivalent-acoustic finite element method is developed for modeling sound absorbing materials, such as seats and interior trim in an automobile passenger compartment. The equivalent-acoustic method represents the sound absorbing material using acoustic finite elements with frequency-dependent material properties determined from the measured acoustic impedance of sound absorbing material samples. Solution of the equivalent-acoustic model within the Nastran computer capability, and coupling of the model with an acoustic finite element model of an enclosure, such as the passenger compartment, are developed. The accuracy of the equivalent-acoustic method is assessed for modeling a sound absorbing material in a one-dimensional impedance tube, a foam layer in a rectangular box enclosure, and the seats in an automobile passenger compartment.