Optimal design of Piezoelectric smart structure for achieving a silent zone in an enclosure

초록

Optimal design of a piezoelectric smart structure is sudied for cabin noise contro. A cubic shaped acoustic cavity with a flat plate which covers one side of the cavity is taken as the problem. Disk shaped piezoelectric sensor and actuator are mounted on the plate and the sensor signal is returned to the actuator through a negative gain. The plate structure is modeled using finite element method which is based on a combination of three dimensional piezoelectric, flat shell and transition elements. The acoustic cavity is modeled using the modal approach which represents the pressure fields in the cavity as a sum of mode shaped of the cavity with unknown coefficients. By using orthogonality of the mode shapes, the finite element equations for the structure coyed with the acoustic cavity are derived. The objective function in the optimization procedure, is to minimize the average pressure at a certain region, so-called silent zone, in the cavity and the design variables are the locations and sizes of the disk shaped piezoelectric actuator and sensor as well as the negative gain. The optimal design is performed at sevral frequencies and the results show a remarkable noise reduction in the cavity. The optimal locations of the actuator and sensor are found to be close to the corners of the plate. The robustness of the optimally designed structure is proven by examining the structure at different frequencies