Minimizing radiated sound power from vibrating shells

A general method of minimizing sound power radiation from vibrating thin shell structures is presented. The method employs finite element analysis for determining structural modes and vibrations, and also a boundary element/wave superposition code for determining sound power radiation. Noise control is accomplished passively by placing optimally sized point masses in locations which permit volume velocity cancellation. The simulated annealing technique is used to determine the magnitude and location of the point masses. Either single-mode or broad-band sound power minimization may be carried out. Two example problems are presented. It is shown that the proposed method agrees quite well with experimental results for a flat plate.