Symmetrization Procedure for Structure-Fluid Cavity System Involving Pseudostatic Correction

Abstract

This paper deals with a pressure-displacement formulation based on the finite-element method of an elastoacoustic coupling problem. Since directly solving the resulting system isCPU intensive for large models, the solution is usually based on only a few uncoupled structural modes in vacuum and rigid cavity modes. However this classical pressuredisplacement formulation leads to nonsymmetric eigenvalue problems. Furthermore, if this method is accurate for weak coupling models, significant errors occur when the truncated modes are coupled to the ones used in the analysis. The present paper suggests a method combining the pseudostatic correction of the truncated modes in modal analysis with a symmetrization technique of the eigenvalue problems. It allows the calculation of the real coupled modes and frequencies, as well as the computation of an accurate elastoacoustic response, even for the strong coupling of a structure with a heavy fluid (liquid). It is less CPU expensive than the classical method, because it leads to a diagonalized system.