### 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
**

**
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*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.