Improved sound transmission loss in an automotive component using piezoceramic patches and dissipative shunt circuits

Noise in a vehicle is generally caused by the vibration of various automotive components, such as the dashboard, door panels, and roof. For example, vibrations caused by the engine may cause a dash panel to vibrate leading to noise in the vehicle cabin. The control of such noise and vibration may be achieved by placing a viscoelastic or other suitable damping material on the automotive component; however, conventional damping materials usually have a high density, which can lead to significant increases in the overall mass of the sound insulation system. A lightweight alternative employs piezoceramic patches connected to a resistor–inductor circuit, where the mechanical vibration, converted into electrical energy by the piezoceramic, is dissipated in the form of thermal heat through the resistor. The presence of an inductive element allows the system to perform in the vicinity of a mode of the vibrating structure, in an effect similar to a resonant vibration absorber. In this work, the damping capacity of this resonant electrical circuit is demonstrated in a dash panel installed between coupled reverberant and anechoic rooms for assessments of sound transmission loss. Finite element simulation and theoretical analysis are used to support the choice of the electrical component values and the correct placement for piezoelectric patches. The resulting sound transmission control is compared to baseline measurements with conventional viscoelastic material thermally bonded to the panel surface. The work is concluded with a discussion on the achieved results and mass saving benefits of the proposed damping technique.