Analysis Of Acoustic-vibration Coupling Characteristics Of Complex Elastic Cavity Based On Smooth Finite Element Method

The elastic cavity structure is a thin-walled structure with higher structural load-bearing efficiency and lower weight,and is widely used in engineering practices such as automobiles,submarines,and airplanes.It is usually under complex working conditions of multi-field coupling such as structural displacement field,sound field,pressure field,etc.When it is subjected to external force or external sound source,the elastic cavity structure will vibrate,and on the one hand,it will cause vibration damage to the structure.,Affect the life and safety of thin-walled components;on the other hand,it will cause a lot of noise inside the cavity,affecting the physical and mental health of the operators.In order to achieve the effect of vibration suppression and noise reduction,sound-absorbing materials are usually laid on the elastic cavity structure to achieve the purpose of noise reduction.Furthermore,a viscoelastic material is laid on the surface of the elastic cavity containing sound-absorbing material and constrained to form a complex elastic cavity structure containing sound-absorbing material and passive confinement layer damping.With the help of the high damping,high damping of the passive confinement layer damping structure The characteristics of simple design,convenient use,and good sound absorption performance of sound-absorbing materials in the middle and high frequency bands can more effectively improve the dynamic performance and vibration response of thin-walled structures.However,there are few researches on this kind of complex elastic cavity structure.Therefore,modeling and analysis of its acoustic-vibration coupling characteristics has important engineering research significance.This article first describes the current research status of the substructures of complex elastic cavities.Existing studies have shown that: since the vibration and noise reduction performance of the passive constrained layer damping structure is achieved by the shear energy dissipation of the viscoelastic layer,the accurate description of the shear force of the viscoelastic layer is also such a complex elastic cavity structure.A key to the accurate establishment of a vibro-acoustic model;at the same time,when the traditional finite element method is used to describe the vibro-acoustic characteristics of a complex elastic cavity,the calculation accuracy of the acoustic stiffness matrix is another important factor in the analysis of the vibro-acoustic characteristics of this type of structure in the middle and high frequency bands.The essential.Subsequently,for the above two key points,based on the complex constant modulus model of the viscoelastic damping material,a finite element model of the passive constrained layer damping beam element with two nodes and eight degrees of freedom was established,and the numerical simulation was effective for the finite element model.The accuracy and accuracy are verified;and based on the triangular element mesh background,combined with the edge smoothing finite element method,the cavity sound field stiffness matrix containing sound-absorbing materials is smoothed to determine the accuracy of the cavity sound field sub-structure dynamics model;Then the passive constrained layer damping beam sub-structure and the two-dimensional acoustic cavity with sound-absorbing material are coupled with the edge-smooth finite element model sub-structure,and the coupling force matrix of the structure field and the sound field is introduced to deduce the two-dimensional complex elastic cavity with edge-smoothness Finite element model;and numerically discussed the acoustic and vibration characteristics of the complex cavity structure under different laying conditions.Based on this,the study of acoustic-structure coupling of complex elastic cavity structures is extended to three-dimensional situations,and a four-node tetrahedral smooth finite element in the acoustic cavity domain,and a three-node21-degree-of-freedom passive constrained layer in the structure domain for more convenient coupling processing are proposed.Damping plate element;through a similar coupling process as in the two-dimensional case,a smooth surface finite element coupling model of a three-dimensional complex elastic cavity with a passive constrained layer damping plate is established;and the material parameters of the passive constrained layer damping structure and the laying position are discussed The influence of factors such as the laying of sound-absorbing materials on the acoustic and vibration characteristics of complex elastic cavities.