Structural Vibration Control Based On Negative Capacitance Piezoelectric Shunt Damping

The self-noise of the sonar platform is originated from hydrodynamic noise,propeller noise and machinery noise.Under the excitation of turbulent boundary layer(TBL)pulsating pressure,the propeller excitation and machine vibration transmitted through the non-acoustic interface to the sonar cabin,and the propeller noise transmitted to the sonar cabin through the acoustic window,the low-frequency vibration of the sonar platform is prominent,which seriously affects the sonar detection capability.The low-frequency vibration control of the sonar platform structure is a key measure to realize noise suppression of the sonar cabin.With support by the National Natural Science Foundation of China and the Shanghai Rising-Star Program,linear spectrum and broadband spectrum vibration control of sonar platform structure based on negative capacitance piezoelectric shunt damping is carried out.The contents of this paper are as follows.Aiming to control the low-frequency vibration of the sonar platform structure under TBL excitation,dynamic model of the electromechanical coupling system of the fluid-plate-piezoelectric shunt circuit is established.The mechanism of the piezoelectric shunt damping in controlling the single degree-of-freedom system and the amplification mechanism of the general electromechanical coupling coefficient(GECC)by the negative capacitance are unveiled.Based on the mechanisms,two piezoelectric shunt circuits,i.e.,resistance-inductance-negative capacitance(RL-NC)and current flowing circuit with negative capacitance(RLC-NC)are proposed and the control effects on the vibration response of plate structure under TBL excitation are studied.The results show that the negative capacitance piezoelectric shunt damping has a better performance,which is effective in controlling the noise radiated by the plate structure under the TBL excitation at various flow speeds.Aiming to control the broadband vibration of the sonar platform structure under TBL excitation,a switching negative capacitance shunt circuit,a sweeping negative capacitance shunt circuit and an adaptive negative capacitance piezoelectric shunt circuit are proposed.The solution method for the time-varying electromechanical coupling systems in timedomain is established.An adaptive optimization algorithm by using the energy method,which is based on the relationship between the electric energy of the circuits and the circuit elements,is established.The results show that the switching and sweeping negative capacitance shunt timevarying circuits can realize low and middle frequency broadband vibration control of low-damping plate structure.The adaptive negative capacitance circuit can adaptively optimize the circuit elements to achieve broadband vibration control,which implys that it is suitable for variable working conditions and piezoelectric arrays.Aiming to control the vibration tranmission through the non-acoustic interface such as cabin and bulkheads under propeller excitation,dynamic model of the electromechanical coupling system of the cabin structure and the piezoelectric shunt circuit is established by using the three-dimensional finite element.The results show that the piezoelectric shunt circuit with both series and parralle negative capacitances can enhance the GECC of the cabin structure with weak strain,which enable to achieve a vibration transmission attenuation greater than 30% at multiple measuring points for single mode control.An experimental study on vibration control of the cantilever beam and the bulkhead in a cabin structure by the negative capacitance piezoelectric shunt damping is carried out.The RL circuit and the negative capacitance circuit are realized by using synthetic impedance.The vibration control sytem with piezoelectric shunt circuits is built.For control of the cantilever beam,the method to determine the optimal circuit parameters is proposed and the control effect of negative capacitance piezoelectric shunt damping are verified.For control of the bulkhead,the dynamic characteristics of the cabin structure is measured through modal tests and strain measurement,then vibration control experiment is carried out for the first-order bending mode of the bulkhead.