Vibration Chracteristcs Analysis And Damping Optimation Of Viscoelastic Damped Plate

The viscoelastic damping surface treatment has been widely applied to the vibration reduction for engineering structure,as it can improve the damping characteristics of composite structure in a wide range of temperature and frequency.In order to improve the damping performance of viscoelastic composite structures,it is necessary to obtain the analysis model scientifically and reasonably.However,the mechanical parameters of viscoelastic materials are frequency dependent,which makes it a challenging task to analyze the vibration characteristics of the aforementioned viscoelastic damping plate.In this paper,the cantilever plate covered with viscoelastic material was used to analyze the natural characteristics,vibration response and damping optimization of the composite structure on the premise of considering the frequency dependence.The details are as follows:(1)For the viscoelastic free damping plate,the quadrilateral shell element was used to obtain the finite element model firstly.Then the iterative algorithms based on the eigenvector increment method and the direct complex mode method to obtain the natural characteristics of composite structure were introduced respectively.Furthermore,the approach of introducing the mechanical parameters of viscoelastic material without considering the frequency dependence was presented.Finally,the cantilever plates attached with ZN-1,3M ISD-112 and DAYD606 viscoelastic materials were chosen to obtain the effects of frequency dependence on natural characteristics of the free layer damping plate.(2)For the viscoelastic free damping plate,the vibration response analysis model under base excitation in frequency and time domain was obtained firstly,and both the viscoelastic material damping and the remaining equivalent viscous damping were introduced in the created model.Then,the vibration responses in frequency and time domain were obtained by the complex mode superposition method and the classical Newmark method respectively.Finally,to obtain the effects of frequency dependence on vibration responses,a comparison was performed for the results obtained by considering and not considering the frequency(or time)dependence of viscoelastic material in the created analysis model,and the effects of other viscoelastic material parameters on vibration response were also studied.(3)For the constrained viscoelastic damping plate,the method of vibration characteristic analysis by considering the frequency dependence was proposed.Firstly,the finite element model of the constrained damping plate was created,and then the natural characteristic of composite plate was obtained.Secondly,both the analysis methods of vibration responses in frequency and time domain for the damping plate under base excitation were presented and two kinds of damping were obtained in the created model.Finally,the influence of frequency dependence on the vibration response of constrained damping plate was analyzed emphatically.(4)For the viscoelastic free damping plate,based on the plate attached with the viscoelastic material under certain area,the analysis model based on genetic algorithm was created to optimize the modal loss factors for single order and multi orders with the coating area fixed.Furthermore,a cantilever aluminum plate with ZN-1 viscoelastic material was used to obtain the optimal location for viscoelastic material.Finally,the experimental results were used to validate the analysis model.For the studies of viscoelastic damping vibration reduction,it is necessary to create the dynamic analysis model of composite structure scientifically and introduce the mechanical parameters of damping material into the created model reasonably.In this paper,the vibration characteristics analysis method for viscoelastic damping plate,the damping optimization method and the method to introduce the viscoelastic material parameters were presented.In addition,the analysis methods developed in this paper can be applied to any structure with the aforementioned damping material,which is of great significance to the application of viscoelastic damping technology in engineering.