An indirect Trefftz method for the steady-state dynamic analysis of coupled vibro-acoustic systems

A new prediction technique, based on the indirect Trefftz method, has been developed for the steady– state dynamic analysis of coupled vibro–acoustic systems. In contrast with the finite element method, in which the dynamic field variables within each element are expanded in terms of local, non–exact shape functions, the dynamic field variables are expressed as global wave function expansions, which exactly satisfy the governing dynamic equations. The contributions of the wave functions to the coupled vibro–acoustic response result from a weighted residual formulation of the boundary conditions. This paper discusses the basic principles and convergence properties of the new prediction technique and illustrates its performance for some two–dimensional validation examples. A comparison with the finite element method indicates that the new prediction method has a substantially higher convergence rate. This makes the method suitable for accurate coupled vibro–acoustic predictions up to much higher frequencies than the finite element method.