Equivalent modeling for vibroacoustic analysis of diffuse acoustic excitation using uniformly distributed delta correlated excitation

Abstract

In space engineering application, diffuse acoustic field is one of the critical design consideration of spacecraft structure. Diffuse acoustic field has equal probability of mutually uncorrelated plane waves from all incident angles over a half-space. Some prediction methods for vibroacoustic response have been developed based on the assumption that the diffuse acoustic excitation can be regarded as a uniformly distributed delta correlated excitation (rain-on-the-roof excitation). This is because a normalized cross-correlation in diffuse acoustic excitation, which is expressed by a sinc function, may be written simply by delta function. In previous researches, it has been assumed that a sinc function can be described by separation of variables, while the application of an exact formula to a simplified normalized cross-correlation in diffuse acoustic excitation has never been discussed, despite its necessity. This paper provides the exact analytical method for a structure subjected to diffuse acoustic excitation applying uniformly distributed delta correlated excitation, based on joint acceptance theory. The method is applied to diffuse acoustic excitation of a flat panel for which several boundary conditions are assumed, so that the results can be compared with those of direct calculation in the diffuse acoustic field, to validate the method for structural designing.