ASA 126th Meeting Denver 1993 October 4-8

4aSA1. Results of acoustic optimization of a point-driven, thin-shelled cube using the boundary element method.

Daniel H. Kruger J. Adin Mann, III Amy Spalding Keith Holman

Dept. of Aerosp. Eng. and Eng. Mech., Iowa State Univ., Ames, IA 50010

The sound power radiated by a thin-shelled cube is calculated from simulated acoustic velocities (equal to the normal shell velocity) using the boundary element method (BEM) [K. A. Cunefare and G. H. Koopmann, J. Vib. Acoust. 113, 387--394 (1991)]. Optimization techniques are then used to predict velocity distributions that result in the minimum output sound power. In future work, recommendations for the addition of passive noise control materials will be defined on the basis of achieving the calculated optimal velocity distribution that will result in the minimum radiated sound power. These criteria are tested on a point-driven, thin-shelled cube in an anechoic chamber. The normal shell velocity is measured using a laser velocimeter. Again, sound power is calculated and the optimal velocity distribution is determined using the BEM. Accuracy of power predictions, based on experimental power measurements and computational examples, as a function of frequency and vibration pattern are studied.