An investigation of active structural acoustic control in resonant enclosures

This dissertation explores two topics in applied structural acoustics. First is the development of a methodology for passive redesign of the plate structure that decreases acoustic-structure coupling and the sound level in acoustic enclosures. The second topic explores the development and implementation of MIMO controllers that were robust and produced meaningful reductions of SPL in the destination enclosure. The scope of this work involved the modeling, simulation, construction, and implementation of these passive and active control concepts. Their performance was evaluated in both simulation and experiment tests. First a passive design methodology based on a parametrically defined FEM (finite element method) model, coupled to a BEM (boundary element method) acoustic model by the modal interaction model approach was developed. Then using FEMLAB (a finite element toolbox for Matlab), a model of the plate was developed and exported as m-code for sensitivity studies and design optimization. Numerous control approaches were then simulated on the state space model of the 3-D enclosure system. These simulations explored different algorithms, controller structures, and system arrangements to determine what approaches were best suited to the ASAC problem. Based on these simulations the required setups and control electronics hardware were designed and built. Then the experimental setup was identified for control design using a variety of standard frequency domain approaches. Finally these control design models were utilized to design and implement controller in experiment. The results and intuitions gained in this investigation are then discussed