Based On Body Thin-walled Parts Constrained Damping Structural Vibration Acoustic Characteristics

As an universal application of transportation, the comfortableness of automobiles has attracted more attention of consumer and automobile manufacturers. Car harshness (NVH) performance and directly related to ride comfort. This paper has discussed how to add at the roof of its board to constrained damping antivibration noise reduction.Firstly introduce the viscoelastic materials material properties, the viscoelastic materials for the constitutive relation analysis, using integral type equation obtains its shear modulus of plural expression. On the structural fe analysis, with shell element simulation interlayer board, finally obtained total stiffness matrix and the mass matrix. Analysis of finite element method, the vibration characteristic computation interlayer board. Respectively by means of replying characteristic value method and mode strain energy method, modified mode strain energy method is discussed, in order to save the computation, then using added the absolute value of mode strain energy method to calculate. Because the viscoelastic material loss factor of frequency dependent, adopt experiment fitting curve to describe the viscoelastic material loss factor, get more accurate results. Finally, this paper on viscoelastic damping in body on the top of the composite structure modal experiment and frequency response experiment. Respectively by using hammering method and add white noise motivation, obtains the nature frequencies of the structure and the damping ratio, and calculation results comparison. Ask out adding damping laminated constraint layer around the frequency response curve contrast diagram, analyze its vibration characteristics. The acoustics of damping composite structure characteristics are analyzed. Because according to experience analysis, body roof radiation noise is bigger, to its add damping constraint structure, application of boundary element method for acoustical simulation analysis, and software for verification. Then, on the structural parameters on the calculation results of the effects are discussed. And optimize the constrained damping of compound structure design. In order to reduce acoustic radiation, may change the constrained damping of compound size, adopting different material, on a dissipation more acoustic radiation vibration energy.