Modeling And Damping Characteristics Analysis On Thin Plate Treated With Active (passive) Constrained Layer Damping

Traditional elastic thin plate structure has been widely used in engineering. For example, floors used in building, stave sheets applied in airplane, decks in ships, all of them can be regarded as thin plates. Vibrations of such structure produce the noise of nature mainly. And it can cause biggish influence on national's property, people's living satisfy and working conditions. Therefore, suppression of such structures'vibration has been actively pursued by people. Recently,due to their better damping performance, passive constrained layer damping and active constrained layer damping plate have replaced the traditional elastic thin plate, and have been applied in the engineering structures gradually. However, at present, all the modeling and the damping characteristic research of active and passive constrained damping laminate structures are still carried out dominantly by finite element method. As the low-order structure functions are used in all the finite element models to carry on the interpolation process, so accuracy of these models is poorer at high frequencies. Simultaneously, scales of such models are usually widely, it is not conducive to carry on further structural optimization and the controller's design. Therefore, it is quite necessary to find a high-precision semi-analytical method for modeling analysis of such structures.Based on linear elastic plate theory, this paper began with the basic equations of an elastic thin plate, and have been deriving its first-order vibration control of differential equations , combined with a new homogenization high precision direct of integration, it have been proposing a transfer matrix method for analyzing such static problems. Through example indicate , the numerical results obtained by the method are consistent with the analytical solutions. This model builds a theoretical foundation for the research of actively or passively constrained damping plate structure.As a main component in active constrained layer damping, the modeling of viscoelastic layer is also the object of this paper. This article introduced several commonly used modeling methods for the material of viscoelastic layer, and analyzed its scope of application. According to these, appropriate method for the mechanical model of viscoelastic material was selected. Then, considering the shear deformation and relation between the displacement of the shell and constrained layer, as well as the interaction between unit and restraint level, combining with the first order ordinary differential equations of the form of matrix equation for primary and constrained layer of the form of matrix equation, the integrated matrix of first order equations of passive constrained layer damping plate was derived . Based on this, one kind of new solution for the damping characteristic analysis of such structure was given. Using the value result obtained by this method to compare with the value result obtained by the present mature large-scale finite element software NASTRAN, the modeling has been confirmed very correctly.Subsequently, some simple introductions about the basic concept and the fundamental equation of piezoelectricity material was made , through the transformation of existing passive constrained layer equations, the vibration equations of the piezoelectric layer(the active constrained layer) was established ,and the derivation process for passive constrained layer damping sheet equations was referred , after having established the integrated matrix of first order ordinary differential equations of active constrained layer damping plate, a semi-analytical model to such structure is given . On this basis, the impact of the boundary conditions, the piezoelectric layer thickness and other external factors on the damping characteristics of ACLD plate impact have been discussed...