A method to couple acoustic linear problems is presented in this paper. It allows one to consider several acoustic subsystems, coupled through surfaces divided in elementary areas called patches. These subsystems have to be studied independently with any available method, in order to build a database of transfer functions called patch transfer functions, which are defined using mean values on patches, and rigid boundary conditions on the coupling area. A final assembly, using continuity relations, leads to a very quick resolution of the problem. The basic equations are developed, and the acoustic behavior of a cavity separated in two parts is presented, in order to show the ability of the method to study a strong-coupling case. Optimal meshing size of the coupling area is then discussed, some comparisons with experiments are shown, and finally a complex automotive industrial case is presented.

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The development of simple, special purpose prediction methods to calculate the acoustic radiation of structures is one requirement of industry. The present study developed and validated a calculation tool to predict the noise radiated by multilayer plates excited by vibrating sources characterized from mobility measurements carried out on the separated elements, namely the multilayer plate and vibrating source. A comparison of the calculations and the measurements presented in this article allows a high degree of confidence in this predictive tool. Although the situation modelled is, a priori, relatively far from an industrial problem involving an excessively noisy machine, the expertise of engineers often helps them determine the section of a plate responsible for the acoustic problem (for example, a section of housing or the sill of a car). The calculation tool would therefore appear to be useful in designing high damping-capacity, multilayer panels of low surface mass for use in correcting the defective part of the machine. © 2000 Institute of Noise Control Engineering.