Research For Vehicle Interior Noise Control Based On Piezoelectric Shunt Damping

With the improvement of living standard and the increase of the auto possession,people demand more and more on the car’s ride comfort. The NVH performance,regarded as comprehensive index of evaluating automotive quality, is paid more andmore attention to. Computers and control technology are widely used in engineering,giving the vibration and noise control technology a rapid development based on theintelligent material. Using smart materials to achieve noise control of closed space hasbecome a hot research topic, and it has a broad prospect for development in the vehiclecompartment, the aircraft cabin, submarines, tanks, etc.In this paper, taking the vehicle interior noise as the research object，the passengercompartment of a car is simplified as a closed rectangular cavity, and then thepiezoelectric ceramic (PZT), a kind of smart materials typical and widely used, isselected for piezoelectric shunt damping circuit to study on the passive control ofvibration and noise through the theories and the experiments.The control effect based on piezoelectric shunt damping mainly depends on threeaspects, that is, the shunt circuit’s type and parameters, piezoelectric patches’parameters and the layout of the piezoelectric patches. In this paper, at first, theelectrical and mechanical characteristics of PZT are expounded, and then the principleand method on vibration and noise reduction of the cavity structure are studied based onthe piezoelectric shunt damping. The typical RL series piezoelectric shunt circuit ischosen. The system’s free response attenuation coefficient is regarded as optimizationobject in pole assignment method and transfer function in transfer function method, sooptimization parameters of the circuit is designed. The problem of large inductance issolved by the simulated inductance.According to piezoelectric shunt damping principle, the positions of PZT transducersare optimized to maximize the electrical energy induced in the PZTs. A rectangular cavityphysical model composed of five rigid walls and a thin elastic plate is built as well asthe finite element model in HYPERMESH. On the condition of the result ofexperimental modal analysis is same as that of calculation modal analysis, the elasticplate modes strain distribution is obtained and the position of largest mode strain isfound out to paste the PZTs.Based on the study of the piezoelectric shunt circuit and the paste position of PZTs, the internal noise of cavity are reduced through controlling the vibration of the plate.For the first-order bound mode response of elastic plate, PZTs are pasted on the elasticplate to form a piezoelectric smart plate, then access shunt circuit, so as to verify theeffect of vibration and noise reduction though the piezoelectric shunt circuit by selectingfrequency. Experimental results show that both the amplitude of the system’s frequencyresponse function and sound pressure of the internal cavity at the first-order modalfrequency are reduced after shunting, which demonstrate the validity of thepiezoelectricity theoretical analysis and the feasibility and effectiveness about thepiezoelectric shunt damping system’s passive control of vibration and noise applied inpassenger compartment of a car and other empty cavity structures. It provides a newway for reducing the interior low-frequency noise of passenger cars.