The comfort of the passenger inside the vehicle is the primary concern of NVH analysis. The noise sensitivity inside the passenger cabin is studied by performing the acoustic sensitivity analysis. In general, acoustic sensitivity analysis using MSC-Nastran[1] involves coupling the grids on the boundary of the acoustic cavity with the structure grids of the body structure.
In MSC-Nastran[1], the coupling between the structure and acoustic cavity can be checked prior to the analysis by using a match grid table and the interface check forces.
It has been found that even though the match grid table indicates that all the boundary grids of the acoustic cavity are coupled with the structure grids, the interface check forces is usually quite high. Ideally, the interface checks forces at the boundary should be equal to zero (numerical zero). It has been found during the course of an internal structure acoustic analysis on a full vehicle that the quality (Jacobian and warpage) of the acoustic elements has a direct influence on the interface check forces.
In order to further understand this relationship, a study has been conducted to identify the influence of element quality on the interface check forces. To start with simple regular geometry such as a cube and a sphere is considered. The study is then extended to the actual acoustic cavity of a full-vehicle model. The present paper is a discussion on the results of such a study to identify the appropriate quality criteria for elements used in such numerical analysis.