Prediction of Acoustic Cavity Modes by Finite Element Methods

Abstract : A finite element method for acoustic cavity modal analysis is presented. The approach utilizes the VAST finite element program eigensolution routines operating on equivalent acoustic mass and stiffness matrices generated from the program ACOUSTIC. Both closed and open cavities can be treated, within the assumption of rigid boundaries. Two elements have been implemented in ACOUSTIC; a 20-noded isoparametric brick element and an 8-noded isoparametric axisymmetric element. The performance of the analysis system has been evaluated via comparison to both analytical and experimental results, and good agreement has been found. Keywords: Finite elements, Frequency analysis, Vibration, Cavities, Modal analysis, Acoustics, Numerical methods, Eigenvalues, Natural modes, Canada.