Reaserch On Vibration Suppression Characteristics And The Evolutionary Topological Optimization Of The Viscoelastic Damped Plates

High damping characteristics of viscoelastic damping materials, allow it to efficient energy consumption structure, often lay in to reduce vibration of the structure on the surface of the plate. However, in the field of design, such as aircraft, due to the strict requirements for structure itself weight and dynamic characteristics, equipped viscoelastic damping materials fully goes against the structure lightweight design requirement, need to limit the amount of viscoelastic material strictly. This paper focus on the research of viscoelastic damping plate structure vibration reduction of dynamic characteristics optimization, make the structure of light weight and vibration reduction effect good. The research work mainly in the following aspects:(1) From the background of the structural damping vibration and optimization design, this paper expounded the viscoelastic damping vibration research significance of structural dynamic optimization, collected the structural topology optimization of various methods and their advantages and disadvantages, summarized and analyzed the application of topology optimization in the practical engineering structure.(2) The viscoelastic plate structural dynamics finite element model was derived,and theory of the viscoelastic damping vibration damping structural dynamic topology optimization theory was analyzed. Based on energy method, with a typical constraint damping board structure as an example, viscoelastic structural dynamics model was established and the model was solved with finite element method; On the basis of dynamic optimization theory, evolutionary structural topology optimization method was introduced in detail.(3) Viscoelastic damped structure material parameters and structure parameters on the vibration reduction effect was preliminary proved, the reduction of vibration mechanics characteristics of viscoelastic structure has carried on the system analysis and optimization. Based on the strain energy theory, using numerical simulation method, based on the research of vibration characteristics of viscoelastic damping cantilever plate structure, viscoelastic material elastic modulus, loss factor and viscoelastic damping materials and constrained layer damping layer thickness ratio were analysed the influence of the structure vibration characteristics. The result has shown that the rational allocation of damping structure parameters can obtain ideal effect of damping noise reduction.(4) A novel optimization method of based on the modal composite damping ratio maximized was proposed, modal vibration response produced by a composite free damping vibration plate structure topology optimization was analysed. Firstly, a dynamic equation for a plate was proposed and a FEM solution to the equation was given, so that the plate’s modal ratio model could be derived. Then, oriented to maximizing multiple modes’ damping ratios, and aimed to make use of damping materials as less as possible and to remain the plate’s modal frequency basically unchanged as well, a topology optimization model was built for the plate. Moreover, the modal damping ratio sensitivity was derived, and evolutionary method was employed to solve the optimization model, which use weighted mean of modal ratio sensitivity to determine the elements’ deletion, so as to avoid checkerboard layout of damping materials in optimization. Finally, a program was accomplished for optimization, so that simulations could be executed on a quadrilateral plate, which invalidate the optimization method proposed in this paper well. Simulations show that a damping plate can obtain better vibration suppression effects, as long as the damping materials distribution on the plate could make multi-mode damping ratio maximize.