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 pow er from a vibrating shell structure using a material tailoring approac h. A finite element method using shell elements is used to predict the vibration response of the shell. The sound power generated by the she ll under a harmonic force input is computed with a lumped parameter/wa ve superposition method. A simulated annealing algorithm is used to fi nd optimal point mass distributions for minimum sound power. It is sho wn that optimal designs are achieved through converting certain mode s hapes of the shell into ''weak radiators'', i.e., modes with low net v olume velocities. Close agreement is found between predicted noise lev els and experimental measurements, thus providing initial validation o f the method as an effective means of finding optimal structural desig ns for minimum sound power. (C) 1998 Academic Press.