STRUCTURAL ACOUSTIC OPTIMIZATION USING THE COMPLEX METHOD

Abstract

An optimization program based on M. J. Box's Complex Method was implemented in a computational design tool for constrained optimization of acoustic environments produced by vibrating structures. The tool can treat interior and exterior environments, and can consider acoustic and structural excitations. The tool integrates finite element and boundary element methods to perform the requisite structural acoustic analyses. The new optimization component described in this paper contains unique additions to Box's original algorithm. The optimizer executes stand-alone, or can be used as a starting point generator for another optimizer, thus creating a hybrid algorithm. This paper describes the new optimizer's algorithm and the results of an example optimization to reduce the interior noise levels within an unstiffened cylindrical shell. Design variables were selected as the shell thicknesses, subject to upper and lower bounds. All analyses were performed at a single excitation frequency. The results demonstrate effective performance of the optimizer, and the potential to obtain significant noise level reductions though the use of other-than-uniform thickness distributions.