Study On The Nonlinear Vibration Characteristic Of Fiber-reinforced Composite Thin Plate Under Thermal Environment

The fiber-reinforced composites have excellent mechanical properties,have high specific strength,high specific modulus,good thermal stability,and certain damping capacity,which are widely used in aviation,aerospace and other important fields.At present,there are a large number of composite thin plate structures made of this type of materials in engineering practice.They are usually constrained by cantilever boundary conditions,with their increasingly complex structures and harsher working environment,their vibration problems become more and more prominent,and most of the components are usually in hundreds of degrees and even thousands of degrees,thermal environment not only affects the mechanical properties,loadcarrying capacity and ultimate strength of composite materials and structures,but also affects the vibration characteristics,in recent years,more and more attention has been paid to the delamination damage and matrix cracking caused by excessive vibration.Besides,the fiberreinforced composites are obviously different from traditional metals,whose macro plate structure will show nonlinear stiffness and damping properties.Therefore,it is of great engineering and academic significance to study the vibration characteristics of composite thin plate structures in thermal environment.In this paper,the TC500 carbon fiber-reinforced/resin composite thin plate is taken as research object,and its vibration characteristics are deeply studied under thermal environment.The specific research contents are as follows(1)Based on the classical laminate theory and Hamilton principle,the vibration characteristics of fiber reinforced composite thin plates in thermal environment are studied.Firstly,the natural characteristic is obtained by orthogonal polynomial method and double beam function method.Then,the frequency-domain response characteristic of composite thin plate under base excitation and the time-domain response characteristic under pulse excitation are investigated by beam function method.In addition,the damping property of composite thin plate under thermal environment is solved by orthogonal polynomial method.Finally,the natural frequency,modal shape,vibration response and damping characteristic of composite thin plate are tested in thermal environment,and the correctness of theoretical calculation method is verified.(2)A nonlinear vibration model of fiber-reinforced composite thin plate with temperature dependence was established according to the temperature dependence of fiber-reinforced composite material parameters.Then,the frequency response function approximation method is used to identify the material parameters of fiber reinforced composites under thermal environment,and the relevant parameters in the theoretical model are determined.Finally,the nature characteristic,vibration response and damping characteristic of fiber reinforced composite thin plates with considering temperature dependence are solved,and the correctness of the theoretical model is verified by examples.(3)A strain energy density function method is proposed to investigate the nonlinear vibration characteristic of fiber-reinforced composite thin plate with considering amplitude and temperature dependence under thermal environment.Firstly,according to Jones-Nelson nonlinear material model,the elastic moduli of the composite thin plates are expressed as a function of strain energy density and temperature,and the nonlinear vibration model of composite plate with considering amplitude and temperature dependence under thermal environment is established by combining the Ritz method and Hamilton theory,so that the nonlinear natural frequencies and vibration responses can be solved by iterative algorithm.Then,TC500 carbon fiber/resin composite thin plate is taken as a research object,and its nonlinear natural frequencies and vibration responses under different excitation amplitudes and temperature conditions are obtained both by theoretical calculation and experimental test.By comparing the results,the correctness of the proposed method is verified.In this paper,the vibration characteristic of fiber reinforced composite thin plate under thermal environment is further revealed which have the important predictive effect on the vibration failure and fatigue damage of composite plate under thermal environment.In addition,this research has important engineering and academic significance for many aspects such as structural design,response prediction and dynamic performance optimization of composite structures.Moreover,the relevant research achievements can provide significant technical support for the application of composite plate in engineering practice.