Analysis On Vibro-acoustic Characteristics Under Complicated Boundary Conditions Of Coupled System Including Coupled Plate And Enclosed Acoustic Cavity

The coupled system including coupled plate and enclosed acoustic cavity are widely used in engineering,so it is of great engineering significance to study their vibro-acoustic coupling characteristics.The materials of the coupled plate are isotropic materials,anisotropic materials and composite materials often used in engineering.Therefore,it is of great theoretical significance and application value to understand the inherent characteristics of the coupled plate under different materials and the vibro-acoustic coupling characteristics of the coupled system including coupled plate and enclosed acoustic cavity.The main research contents are as follows:(1)The analytical model of the L-shaped coupled plate and the coupled system including L-shaped coupled plate and enclosed acoustic cavity under isotropic materials and arbitrary boundary conditions is established.The displacement functions of the L-shaped coupled plate structure and the sound pressure functions of the enclosed acoustic cavity are described by the improved Fourier series method.The structural energy functional,the acoustic cavity energy functional and the plate-cavity coupled energy functional are superimposed.The Rayleigh-Ritz method is used to find the extremum of the energy functional,and the solving equation of vibration characteristic is obtained.Compared with the results of FEM and the existing literature,the analytical model established by the proposed method has good convergence characteristics and computational accuracy.(2)The analytical model of the U-shaped coupled plate and the coupled system including U-shaped coupled plate and enclosed acoustic cavity under anisotropic materials and arbitrary boundary conditions is established.Based on accuracy and convergence,the effects of anisotropy on the vibro-acoustic coupling characteristics of the coupled system including U-shaped coupled plate and enclosed acoustic cavity are mainly studied.Under free vibration and forced response,as the anisotropy increases,the natural frequency also increases,and the displacement curve also offsets accordingly.(3)The analytical model of the O-shaped coupled plate and the coupled system including O-shaped coupled plate and enclosed acoustic cavity under composite materials and arbitrary boundary conditions is established.Firstly,the constitutive relation of composite laminates is studied.Then,the coupled energy functionals of bending vibration and in-plane vibration are given.Finally,the relevant modal characteristics and response characteristics are obtained.In the numerical result analysis,the influence of the number and the angle of the laminates on the vibration characteristics of the coupled system is mainly studied.As the number of layers increases,the natural frequency also increases.For the coupled plates of composite materials,the same-order natural frequency is symmetrical about a certain angle.(4)Fully considering the existing experimental environment,the modal testing platform of the coupled plate and response test platform of the coupled system are designed and built under clamped boundary condition.The three structures studied in this paper all involve the isotropic materials.The isotropic material is easier to obtain,so the filling materials of the plate structure used in the experiment are all isotropic materials.Through data comparison and error analysis,the correctness of the theoretical analysis model of the vibro-acoustic coupled system established in this paper is further verified.It also deepened the understanding of the coupling mechanism between the coupled plate and the closed acoustic cavity.The present method can be further study the vibro-acoustic coupling characteristics under the multiple external fields,and form a complete set of analysis techniques for structures and plate-cavity coupled systems,which has a great reference for the theory and application in this field.