The use of simple three-dimensional acoustic finite elements for determining the natural modes and frequencies of complex shaped enclosures
Tetrahedral and cuboid finite elements, with a linear variation of the pressure between the nodes, are used for finding the natural frequencies and modes of an acoustic enclosure. The first part of the paper is concerned with testing the elements on a parallelepiped enclosure. It is shown that the solution converges to the exact solution as 1 1/ N2 where N is the order of a three-dimensional grid. In the final part the method is used for calculating the modes and frequencies of the passenger enclosure of a car and good agreement is shown with existing experimental results.