Reducing Radiated Sound Power of Plates and Shallow Shells by Local Modification of Geometry

The application of structural optimization for passive noise control has received increasing attention in recent years. The optimization of shell geometry represents a concept that changes local stiffness without increasing the structural mass significantly. In this paper, the modification of structure by simple local modification functions is explored. To describe the general radiation behavior of a structure, the frequency averaged radiated sound power is evaluated. A relatively large frequency band is investigated. Since a gradient based method for optimization is applied, the efficiency of the process can be improved by appropriate initial parameter sets. Such sets are identified by parameter studies with respect to different load cases. The local modification function may then be deployed at points of high structural mobilities. The modification concept is exercised with a simply supported square plate under harmonic pressure excitation.