AN EFFICIENT COMPUTATIONAL SCHEME FOR EVALUATING THE RESPONSE OF A STRUCTURE SUBJECTED TO RANDOM ACOUSTIC EXCITATIONS

摘要

Space vehicles are subjected to a severe fluctuating external-pressure loading when their rocket-propulsion system are operated in the atmosphere. Such acoustic excitation can be assimilated to a stationary random process. The usual 'diffuse' nature of the incident acoustic field needs some consideration which is addressed in the paper, The excitation is described in terms of overall sound pressure level (and its related frequency spectrum) and appropriate spatial correlation function. In addition, the dynamic behavior of aerospace components can be strongly affected by the surrounding fluid medium so that coupled (i.e. fluid-structure interaction) effects have to be accounted for. The numerical treatment of such random excitations acting on a coupled elastic structure is precisely the subject of the present paper. The discrete model relies on an hybrid FEM-BEM technique. A displacement-based FEM model is selected for the structure while an advanced indirect BEM model is used for the acoustic fluid medium. An efficient solution scheme is proposed in order to handle the random response. Application to a plate structure and an antenna in a diffuse field are presented and compared to reference results.