On the Applications of the Boundary-Element Method to Acoustical Field Studies of Vibrating Structures

This paper describes the applications of the Boundary-Element Method (BEM) for studies on acoustical field of various vibrating structures. The studies emphasize the numerical aspects of the BEM. Both acoustical near and far fields of the vibrating structures are investigated in this work. The vibrating structures considered in this application studies are a circular piston in an infinite, rigid baffle and cantilever-type beams. In the case of piston in an infinite baffle, instead of using the method of images, the free-space Green’s function is used to evaluate boundary integral equation by including both piston and baffle surfaces. The influence of the stationary baffle in the case of piston is further investigated. The beams considered are of both rectangular and circular cross sections. The results obtained by BEM have compared well with the available results from classical methods. The studies indicate that in the application of BEM in such problems both the element size and the number of elements including stationary surface have significant effect on the results obtained. The studies have yielded that very good results are obtained when the largest dimension of an element is equal to 0.2 times the acoustic wavelength (in air) of the frequency of acoustic radiation.