Pseudostatic corrections for the forced vibroacoustic response of a structure-cavity system

The analysis of the coupled vibroacoustic behavior of a structure-cavity system is often performed using the in vacuo structure modes and the rigid cavity modes. Unfortunately, the use of such a modal basis can result in a poor convergence when the high-frequency modes of one of the two subsystems are coupled to the low-frequency modes of the other subsystem. This problem is made critical by the lack of a reliable criterion for selecting the number of kept modes for each subsystem. This paper shows that the effect of modal truncation is critical for the convergence of the method and that the convergence can be greatly improved using pseudostatic corrections for both the structure and the cavity. The theory behind the proposed technique is presented together with two generic problems exhibiting strong coupling: (i) an elastic cylindrical cavity filled with air; and (ii) an elastic plate coupled to a rectangular cavity filled with water.