TIME-DOMAIN FORMULATION OF THE METHOD OF EQUIVALENT SOURCES

A time domain formulation of the concept of equivalent sources is pres ented. The concept of equivalent sources is traditionally used in the frequency domain and it represents an attractive alternative to the bo undary element method for calculating the sound radiation from vibrati ng structures with arbitrary shapes. The theoretical background of the method of equivalent sources has been developed during the last few y ears and it has been successfully proven for different problems, altho ugh a number of questions are still open, such as the optimal position ing of the sources or the optimal source type. The time domain formula tion is shown to lead to a further improvement of the method. A faster algorithm and thereby a lower demand of computational power are conse quences of changing from the frequency to the time domain. The theoret ical formulation is presented including arbitrary boundary conditions. With this general formulation the method is usable for sound radiatio n problems as well as for scattering problems. The functioning of the method is demonstrated for the sound radiation from a rectangular box. A discussion of parameters determining the accuracy of the method is included.