Interval and subinterval perturbation finite element-boundary element method for low-frequency uncertain analysis of structural-acoustic systems

Abstract

Uncertainties exist widely in the structural-acoustic systems, due to the physical imperfections, model inaccuracies and system complexities. To deal with the uncertainties, the interval perturbation and subinterval perturbation techniques, for the first time, are extended and integrated into the hybrid finite element-boundary element method (IPFEM/BEM) in this work. Firstly, the structural part of structural-acoustic systems is modeled using finite element method (FEM) and acoustic cavity is modeled by boundary element method (BEM). Then the interval perturbation technique is introduced to establish the interval perturbation equations of the system. For large uncertainty levels, the interval of parameters is divided into smaller sub-intervals to improve the accuracy of proposed IPFEM/BEM (sub-interval perturbation finite element-boundary element method, SIPFEM/BEM). The proposed IPFEM/BEM and SIPFEM/BEM are verified by two numerical examples. The results obtained by IPFEM/BEM, SIPFEM/BEM and Monte-Carlo method are compared. It is found that IPFEM/BEM and SIPFEM/BEM is reliable for the frequency response analysis of structural-acoustic systems with small or large uncertain levels.