Investigation of acoustic-structure interaction problems

A new procedure to formulate and analyze vibration problems of structural-acoustic coupled system has been established. At first, free vibration analysis of the acoustic system by the modal expansion method was applied for elliptic cavities, then the system equations of structure-acoustic coupled systems are formulated utilizing the concept of the equivalent mass source. The modal expansion method and a matrix transformation technique are used to solve the free and forced vibration problems. The final formulation of this method in the free vibration problems gives rise to a standard eigenvalue problem. The validity of the procedure is verified by comparing its results with the exact solutions for a one-dimensional coupled system. Parameters dictating coupling effects are also identified and discussed. In the final part of the dissertation, a new solution method was introduced to solve the forced response of acoustic-structure coupled system, which includes damping and absorbing elements. The new method proposed here does not require any matrix inversion as has been used in conventional methods. The method proposed here also has a better numerical efficiency. The other advantage of the method is that the effect of the absorbing material on the system response can be modeled as a virtual sound source with its own magnitude and phase. The system frequency response functions can be expressed as a summation of the uncoupled component modes of the system, The procedure for the forced response solution was again confirmed by comparing its results with the exact solution available for the one dimensional case. Possible applications of the method are also discussed.