Modeling And Parametric Influence Of Sound Absorption Of Acoustic Coatings With Embedded Piezoelectric Layer

As acoustic stealth equipment widely used in underwater maneuvering platforms,acoustic coatings can absorb acoustic waves from active sonar and suppress the vibration of the shell and isolate the noise inside.Therefore,the acoustic coatng is an important equipment that can effectively evade the detection of active and passive sonar.With the development of detection technology,how to improve the acoustic insulation performance of the acoustic coating has become a key problem to be solved.In this paper,with the objective of achieving low-frequency broadband sound absorption/insulation of acoustic coatings,the cavity structure of acoustic decoupling coating was topologically optimized by finite element numerical method,and a new type of decoupling coating with U-shaped cavity was proposed based on the optimization results.In addition,the acoustic absorption performance of the acoustic coatings with embedded piezoelectric layer were studied.The research is carried out around its analytical model,simulation and parametric analysis.The main research contents and results of the article are as follows.Numerical calculation models of acoustic performance of acoustic coatings under atmospheric pressure and static pressure were established respectively,and a twodimensional axisymmetric model combined with topology optimization was proposed for decoupled acoustic coatings to find the optimal acoustic cavity structure rapidly.A density-based topology optimization method was used to optimize different regions of the coating.Based on this,a coating structure containing a U-shaped cavity was obtained.The vibration isolation performance of the U-shaped coating is better than that of a typical cylindrical coating under both atmospheric and hydrostatic pressure.In addition,the vibration isolation mechanism of the U-shaped structure was analyzed and the influence of the U-shaped cavity position on its vibration isolation performance was considered.The results show that the sound insulation performance of the U-shaped coating is better than that of the cylindrical coating and this topology optimization method can provide some guidance for the structural design of the acoustic coatings.The intrinsic equations and the expressions for the elastic,piezoelectric and dielectric constants of the 1-1-3 piezoelectric composites were derived to obtain equivalent parameters that can describe the macroscopic properties of the materials.At the same time,the influence of the content of each component in the piezoelectric material on the electromechanical coupling coefficient,density,longitudinal sound velocity and acoustic impedance was studied.By changing the ratio of each phase component of the piezoelectric material,the equivalent parameters can be adjusted to achieve the expected performance requirements.The analytical and simulation models of the piezoelectric shunt structure are established.The piezoelectric shunt structure is introduced into the acoustic coating,and the joint simulation of the two is established.Based on the transfer matrix method,the surface impedance equations of the piezoelectric material layers under rigid backing and air backing conditions were derived to solve the sound absorption coefficients respectively.The influence law of circuit parameters on the sound absorption coefficient of the piezoelectric shunt structure was analyzed,and the optimal parameters of the shunt circuit under rigid backing and air backing conditions were obtained based on the impedance matching and exhaustive search methods,respectively,to achieve the best sound absorption performance.In addition,for the sound absorption performance of the acoustic coatings with embedded piezoelectric layer,and the influence law of the cavity,the thickness of piezoelectric layer and steel plate on the sound absorption coefficient was analyzed in depth.It is shown that the introduction of the piezoelectric shunt structure in the acoustic coating can effectively improve its low-frequency sound absorption performance.The low-frequency broadband sound absorption of the coating was realized.