A Study On Vibro-Acoustical Characteristics And Optimized Analysis Of Constrained Damped Sandwich Plates

As the hazards of vibration and noise are known, there are some active demands for damping and denoising. Using viscoelastic material is one of the most important methods for vibration and noise control. Due to the wide use of viscoelastic material to control the vibration and sound radiaton in engineering and the appearance of new viscoelastic material in recent years, the sound radiation problem of viscoelastic complex structures becomes more and more important.As we all know, there are two different layouts of viscoelastic coating, one is free layer damping, the other is constrained layer damping. The former consumes the mechanical energy by the tension and compression deformation of viscoelastic material. The latter consumes the mechanical energy by shearing deformation of viscoelastic material. And the latter can work better than the former in the effectiveness of vibration reduction and denoising. Theoretical analysis and numerical computation for dynamic characteristic and sound radiation of the sandwich plate with constrained damp layer are presented in this paper.In the paper, the fundamental theory of sound radiation is briefly introduced. Approximate parse solution for vibration and sound radiation of normal elastic structures is expatiated. And the same time, the solution based on finite element and boundary element theory which compute the vibration and sound radiation of normal elastic structures is explained. The end, the fundamental theories of sound radiation, finite element model of viscoelastic structures are introduced. The different layouts of viscoelastic coating are discussed. The cell matrix and finite element dynamic equation of viscoelastic structures is researched. And the coupling vibration and sound radiation equations of viscoelastic composite structure are presented.The sound radiation of viscoelastic composite sandwich plates is researched in this paper. The first, A finite element method to compute the natural frequency of sandwich plates is found. The second, The validity of computing dynamic response based on some examples is verified. From the result of computing, the conclusion is that the method is reasonable and precise. The last, sound radiation characteristics and denoising optimization design of the viscoelastic composite sandwich plates structure which is stimulated by force are investigated. Based on ANSYS and SYSNOISE software, How the thickness, stiffness, boundary conditions, material density, elastic module and damping factor of viscoelastic structure to affect the sound radiation is discussed in the paper, then some useful conclusions are drawn from them, which will give engineers a guideline to choice the optimization damping. The method can be used in large scale and complex sandwich structures, and it can gives a convenience and effective method for denoising engineering.