Noise And Vibration Control Based On Piezoelectric Shunt Damping Technology

With the development of aviation industry,the aerospace and aircraft structures tend more and more large and complex.These structures have the characteristics of lower–natural frequencies,higher modal density,lower–damping and lower–mass.The noise and vibration problem has become an increasingly important issue for these structures.The suppression of aircraft interior noise is of major importance as the environment inside aircrafts affects pilots,crew and passengers.Noise and vibration inside aircraft cabins cause increasing risks in health and in particular performance of flight crew and cabin crew as well as a discomfort for the passengers.Therefore,it is very important to develop a new passive noise and vibration control device that is used to reduce aircraft interior noise across a broad band frequency spectrum.The development of piezoelectric smart materials brings new ideas to the aircraft noise and vibration control.Moreover,piezoelectric shunt technology has been applied in engineering practice recently.The theoretical modeling,numerical calculations and experiments by using shunt damping technology is throughout this thesis.The main work in this thesis includes the design of piezoelectric shunt circuit for control vibration and shunt loudspeaker for noise control.The first part of this thesis studies a theoretical and experimental comparison of different piezoelectric shunt damping techniques:(1)The coupling model for piezoelectric beam and piezoelectric plate are established.The responses of the piezoelectric actuators for beam and plate structures are presented in first few natural frequency ranges.And the calculation results are verified by experimental results.(2)Piezoelectric shunt damping circuit designed by pole placement method is presented.The optimal inductance value and optimal resistance value are obtained.Numerical calculations are performed to test the vibration control effect,and the results by presented method is compared to the traditional optimization method.(3)A new shunt circuit based on the current mode theory is developed.Comparison of the presented shunt circuit to the traditional voltage mode shunt circuit are presented.The numerical calculation results show that the inductance value and resistance value of the presented shunt circuit can be adjusted independently.Therefore,the control system can reach the optimal control frequency and damping.(4)In order to verify the control performance of the designed piezoelectric shunt damping system,an experiment was set up.The experimental results show that the designed shunted damping system has a good effect on the vibration control of the structures.Furthermore,the experimental results agree well with theoretical and numerical calculation results.The results show that the amplitude of the clamped vibrating beam and plate can be decreased 6 dB and 5 dB,respectively.To further investigate the ability of the shunt damping technique,a novel shunt loudspeaker is proposed by connection a shunt circuit with an electromagnetic loudspeaker.The main work in this parts includes:(1)A coupled duct–loudspeaker model and a room–loudspeaker math model is established.(2)A shunt circuit of shunt loudspeaker is presented.The parameters of shunt loudspeaker(such as location and shunt circuit parameters)are optimized.(3)Finally,the control performance of the presented shunt loudspeaker was verified by numerical calculations and experiments.The results show that proper tuning of the shunt loudspeaker can result in noise reduction in duct about 10 dB.