Acoustic Diagnostic Analysis Using BoundaryElements

Abstract

The prediction of sound levels in vehicles and the environment is now a common practice in engineering. This has been made possible by the development of powerful tools based on boundary element techniques. These provided the user for the first time easy to use tools to predict sound levels. This paper will describe a generation acoustic system based on boundary elements which not only enhances the accuracy of the modelling, but also provides powerful diagnostic facilities to enable the user to identify the main contributions to the sound intensity at a any point of interest. Applications are presented. 1.0 Introduction The products of many industries can benefit from improved acoustic design. The same technology which has been successfully applied to simulate the performance of structures can be applied to provide the acoustic engineer with the information necessary to ensure the design satisfies performance specifications and/or regulations imposed by governments and standard bodies. The use of computer simulation offers major advantages over trial and error prototyping in the quest for improved products (e.g., quieter products). Acoustic problems can in general be classified into three categories. Interior problems where the domain is finite (e.g., computing the sound field in a vehicle or building), exterior problems where the domain is infinite (e.g., radiation from a machine or vehicle) and coupled interior/ exterior problems where the problem consists of a combination of the first two. While the finite element method has been used with some limited success in the first category, the major advantages of the boundary element method in the second two categories has enabled it to become the method of choice for most engineers wishing to simulate acoustic problems. In first acoustic analysis systems the software simply predicted the acoustic field due to sound sources or vibrating bodies. The interpretation of the results and following action Transactions on Modelling and Simulation vol 7, © 1994 WIT Press, www.witpress.com, ISSN 1743-355X