Radiated noise control via structural vibration control

Interior noise control in a cabin enclosure using active vibration control of the walls of the enclosure with discrete piezoelectric actuators and sensors is addressed. A hybrid approach using finite element formulation for the radiating walls of the enclosure. We use an exact 3D formulation without making the usual approximations for the electric field in the piezoelectric devices. The electrical boundary conditions and the charge on the electrodes are treated correctly Computational time is optimized by using plate elements for the structure and 3D element for the devices with transition elements to connect them. A PD-controller is used to relate the voltage output of the sensor in open circuit conditions to the charge input to the actuator via appropriate gains to control vibrations. The acoustic part of the problem is modeled via a modal approach The modal representation of the pressure is used as a mechanical force term on the structure which can be written in terms of a virtual mass. The driving term for the acoustic field is in turn the displacements on the surface of the radiating walls which is computed from the structural equations. This accounts for the acoustic field-structure interaction and the equations are solved simultaneously. By adjusting the feedback gain, significant noise reduction is achieved globally within the cavity for the dominant vibrational modes of the radiating panel.