The use of modal tailoring to minimize the radiated sound power of vibrating shells: Theory and experiment

A numerical design tool is presented for minimizing radiated sound power from a vibrating shell structure using a material tailoring approach. A finite element method using shell elements is used to predict the vibration response of the shell. The sound power generated by the shell under a harmonic force input is computed with a lumped parameter/wave superposition method. A simulated annealing algorithm is used to find optimal point mass distributions for minimum sound power. It is shown that optimal designs are achieved through converting certain mode shapes of the shell into "weak radiators", i.e., modes with low net volume velocities. Close agreement is found between predicted noise levels and experimental measurements, thus providing initial validation of the method as an effective means of finding optimal structural designs for minimum sound power.