Study On Vibration Characteristics Of Multiple Viscoelastic-layered Fiber-Reinforced Laminate With Outside Metal-Layers Plate

With a long time work,the vibration time of the aircraft is long and the vibration amplitude is large and the failure problems such as excessive vibration,friction and fatigue failure are becoming more and more serious.Traditional fiber reinforced materials and fiber metal materials can not meet the increasingly demanding working environment.Multiple viscoelasticlayered fiber-reinforced laminate with outside metal-layers(MVFLM)which has the advantage of fiber-reinforced composite,viscoelastic material and metal material including light weight.strong vibration and noise reduction ability,good impact resistance,good fatigue resistance performance,outstanding corrosion resistant,easy maintenance and low cost,can play a key role in vibration and noise control of aircraft and other weapons.In addition,MVFLM is different from conventional materials in that they have obvious anisotropy,and the vibration of its laminated plate also shows complex nonlinearity,which brings great difficulty to traditional linear and nonlinear modeling and calculation.Therefore,it is of great scientific significance to study the linear and nonlinear vibration characteristics and theoretical analysis model of its laminated plate.In order to solve the above problems,this paper takes MVFLM plates as the research objects to study the vibration characteristics of this type of laminated plate.The specific research contents are as follows:(1)Based on the classical laminate theory and high-order shear deformation theory,the linear vibration characteristics of the MVFLM plate are solved with introducing the influence of experimental damping.The displacement field function of viscoelastic layer and fiber layer is expressed by high-order shear deformation theory and classical laminate theory,respectively.The experimental damping is applied instead of the theoretically calculated damping matrix.The linear vibration model of laminated plates is established by Ritz energy method.And the linear vibration characteristics are obtained by the orthogonal polynomial method.In addition,the analysis flow of the linear vibration characteristics of the laminate is shown.At the same time,the vibration characteristic test system of MVFLM board was built,and the two MVFLM plates with different geometric parameters were taken as the research objects.The vibration characteristics of the laminate were obtained,and the correctness is verified by comparison with the experimental results.(2)The nonlinear vibration characteristics of MVFLM plate are studied based on the strain energy density function method with considering the influence of material nonlinearity.First,referring to the Jones-Nelson nonlinear material model,the elastic modulus and loss factor of fiber reinforced composites and viscoelastic materials are expressed as a function of strain energy density.The nonlinear vibration model of MVFLM plate is established by Ritz energy method in combination with classical laminate theory and high order shear deformation theory.Second,the particle swarm optimization algorithm is used to identify the material parameters,and the fitting coefficients in the nonlinear theory model of the materials are obtained by using the MATLAB fitting tool.Then,the iterative algorithm is used to solve the nonlinear vibration characteristics of the MVFLM plates,and the analysis process of the nonlinear vibration characteristics is proposed.Finally,two MVFLM plates with different geometric parameters are taken as the research objects.The nonlinear vibration characteristics of the corresponding laminated plates under different excitation amplitudes are obtained by theoretical calculation and experimental test,respectively.The correctness of the theoretical analysis method is verified by comparison.(3)The nonlinear vibration characteristics of MVFLM plates are studied considering the influence of material and geometric nonlinearity,which combine with the strain energy density function method and Von Karman geometric nonlinear principle.Firstly,based on the established theoretical model considering the nonlinear influence of materials,the nonlinear vibration model of the laminated plates is established by the Ritz method,which combine with the high-order shear deformation theory and the Von Karman geometric nonlinear principle.Secondly,the Ritz parameters considering geometric nonlinear effects are obtained,and the fitting coefficients in the material and geometric nonlinear theory models are obtained by identify the material parameters with the particle swarm optimization algorithm.Then,the iterative algorithm is applied to solve the nonlinear vibration characteristics of the MVFLM plates,and the analysis process of the specific nonlinear vibration characteristics is proposed.Finally,two MVFLM plates with different geometric parameters are taken as the research object.The nonlinear vibration characteristics of MVFLM plates under different excitation amplitudes are obtained by theoretical calculation and experimental test respectively.The correctness of the theoretical analysis method is verified by comparison.In this paper,the research work further reveals the vibration characteristics of the MVFLM plates,which has important predictive effects on the vibration damage and fatigue damage of MVFLM plate structural parts.It has important engineering and academic significance on the dynamic design,response estimation and performance optimization of structural systems,and relevant research results can provide important technical support for the application of MVFLM board components in engineering practice.