Research On Low Frequency Sound Absorption Characteristics Of Acoustic Anechoic Coatings Based On Piezoelectric Shunt Damping Technology

To reduce the detection echo of the enemy’s sonar and suppress the internal vibration of the submarine to radiate outward through the shell to reach the target of submarine acoustic stealth,various naval powers are racing to develop underwater acoustic covering technology to reduce the intensity of the target and gain the initiative in wartime.With the development of low-frequency active sonar detection technology,the energy dissipation way of the traditional passive acoustic anechoic coatings is limited,and its sound absorption tends to limit.Therefore,all countries are actively studying and expanding the energy dissipation of the acoustic anechoic coatings.Due to the low acoustic impedance,the piezoelectric composite material can achieve impedance matching with seawater and retain the original piezoelectric effect of the piezoelectric material.Based on this,the paper proposes a new type of semi-active acoustic anechoic coatings containing piezoelectric composite material.The shunt circuit expands the form of energy dissipation and broadens the low-frequency sound absorption performance.The main research contents of this paper are as follows:Based on the uniform field theory,the equivalent model of 1-3 piezoelectric composites is constructed and the macroscopic mechanical and electrical parameter expressions are derived,and the constitutive equations of piezoelectric composites are derived from this.By comparing and analyzing theoretical calculations and finite element simulation results,the influence of geometric parameters and material parameters on the sound absorption coefficient is verified.Combining structure-borne sound propagation theory and sound-structure coupling boundary conditions to construct the sound transfer matrix of the sound absorption coefficients,and derive the global sound absorption coefficients of the cover layer,analyze the sound absorption characteristics and energy dissipation mechanism of the uniform rubber layer and the non-uniform rubber layer with cavities.Study the influence of rubber layer material parameters,geometric parameters,and cavity structure on the sound absorption performance of the acoustic covering,and complete the optimization of the passive acoustic anechoic coatings.The piezoelectric shunt damping technology is introduced into the acoustic covering for semi-active control,and the electromechanical equivalent circuit network model is obtained by using the electric-acoustic analogy method,and a negative capacitance circuit is constructed to offset the clamping capacitance of the piezoelectric composite material,thereby expanding the sound absorption bandwidth.According to the electromechanical equivalent circuit model,the expression of the sound absorption coefficients of the external negative capacitance shunt circuit is obtained,and the energy loss factors of different types of shunt circuits and their influence on the sound absorption coefficients of the acoustic anechoic coatings are analyzed.Finally,the dual-channel transfer function method underwater acoustic test technology is used to verify the sound absorption performance of the designed anechoic coating.