Optimal placement of piezoelectric actuators for active noise control

Abstract

Optimal placement and size of disk-shaped piezoelectric actuators is studied to reduce the radiation of sound into the space above a plate structure when excited by an acoustic pressure field produced by a noise source located below the plate. Finite element modeling is used to simulate tbe piezoelectric active structure. The objective of the optimization procedure is to minimize the sound energy radiated onto a hemispherical surface of given radius, and the design parameters are the locations and sizes of the piezoelectric actuators, as well as the amplitudes of the voltages applied to them. To allow for variations in the locations of piezoelectric actuators on a flat plate, an automatic mesh and boundary condition generation program is developed based on the idea of moving mesh templates for complicated regions near piezoelectric actuators. This new contribution enables the optimal design of active plate structures for noise control problems. Numerical results of the optimal design at the resonance and off-resonance frequencies show remarkable noise reduction, and the optimal locations of the actuators are found to be closer to the edges of the plate. The optimized results are robust such that when the acoustic pressure loading is changed, the radiated sound is still reduced. The robustness of the design is studied by fixing the position of the actuators and optimally adjusting the actuator voltages to obtain broadband noise reduction.