Piezoelectric controlled noise attenuation of engineering systems

In the paper, a recently developed overall numerical approach is presented, which is suitable to design smart engineering systems to actively reduce sound radiation. For this reason, piezoelectric patch actuators and sensors are attached to the surface of the structure to control structural vibrations. In the paper, the theoretical background of the design process is briefly presented first. The basis is a combined finite element and boundary element approach. Electromechanical coupled finite elements are applied to model the structure as well as the piezoelectric patches. The finite element method is also used to model fluid domains which are partially or totally bounded by the structure. Boundary elements are used to characterize the unbounded acoustic pressure fields. Then it is shown how control algorithms can be included into the simulation process, which finally results in an overall simulation approach for structural acoustic systems including control. The numerical approach is also verified by measurements. The experimental setup enables measurements of the uncontrolled and controlled radiated sound fields using a microphone array. A comparison between the measured values and those predicted by the proposed coupled finite element-boundary element approach shows good agreement. Finally, it is demonstrated how the approach can be applied to real engineering systems. As an example, noise reduction of a car engine with a smart oil pan is presented. Again, the numerical results of the uncontrolled and controlled behavior are in good agreement with the measurements. It can be concluded that the proposed overall numerical approach can be applied to design real engineering systems, which are able to actively reduce the noise level.