Optimization of transducers for active structural acoustic control of complex structures using numerical techniques

A general procedure for the optimization of control actuator forces and locations to minimize the total radiated sound power from complex structures has been developed. This optimization procedure interfaces finite and boundary element models with non-linear optimization techniques. The optimization procedure was used to perform parametric studies of Active Structural Acoustic Control (ASAC) on a simply supported plate with various discontinuities such as point mass, line mass, and spring mass systems. These system models were harmonically excited by an off resonance point force of 550 Hz and controlled by piezoceramic actuators. Although the excitation frequency is the same for each of the cases studied, the eigenproperties change with alteration of the physical parameters of the system. Therefore the excitation frequency for each case is effectively different, as is its response. This optimization procedure was very effective in reducing the total radiated sound power from these complex structures. The addition of a second optimized actuator resulted in additional attenuation of varying extent, highly dependent on the discontinuity. The locations of the optimized actuators were also found to be very sensitive to the discontinuity. It was also observed that the optimal location of a single actuator changed very little with the addition of a second actuator. The accuracy of this sophisticated model was verified by comparing solutions from modal based analytical and assumed mode models for simple and complex structures. Some unique aspects of this procedure are that it requires a single implementation of the finite and boundary element solution, and that the finite element forced response solution is not required. Therefore, this ASAC actuator optimization procedure shows potential for application to any structure that can be accurately modeled with finite element software.