Research On Vibration Characteristics And Active Vibration Control Of Laminated Thin-Walled Cylindrical Shell

Thin-walled cylindrical shells are widely used in national defense,energy,machinery,civil engineering and other fields due to their simple structure and good mechanical properties.The mechanical properties and structure of the thin-walled cylindrical shell seriously affect the performance and reliability of the above-mentioned machinery.Especially in complex load environments,there will be risks such as large vibration and high fatigue,and the requirements for the cylindrical shell structure will be higher.In recent years,with the development of the material and manufacturing field,many new shell structures have been produced.For example,the composite laminated shell and the piezoelectric laminated shell studied in this paper are two important shell structures.The structure uses laminated shells of different materials to produce different dynamic properties and achieve different vibration control effects.Therefore,it is very important to study the vibration characteristics and vibration control of the cylindrical shell structure to provide reference for its dynamic design,thereby increasing the performance and life of the mechanical structure.In this paper,the composite and piezoelectric laminated cylindrical shells with the non-continuous electric boundary condition are studied.The dynamic model of laminated cylindrical shells is established.The vibration characteristics and the vibration control are studied.The main research contents include the following aspects:Firstly,the Chebyshev polynomial is used as the admissible displacement functions,a set of artificial spring are used to simulate different boundary conditions,and the Lagrange equation is used to establish the differential equation of the composite laminated cylindrical shell.The accuracy of the model is verified by comparing the frequency parameters.The effects of boundary conditions on the natural frequency of the cylindrical shell and the mode shape are studied.Secondly,considering the geometric nonlinearity caused by large vibration,the nonlinear differential equations of the composite laminated cylindrical shell is established,and the nonlinear differential frequency response is obtained by numerical method.The effect of the boundary conditions of non-classical boundary condition on the nonlinear amplitude-frequency response are studied.Third,based on the lamination principle and introducing the piezoelectric material,the differential equation of electro-mechanical coupling motion of laminated laminated cylindrical shell is established,and the coupled differential equation is decoupled by negative speed feedback strategy.After the model is verified,the piezoelectric layer position optimization index are established,and the multi-objective particle swarm optimization(MOPSO)algorithm is used to obtain the best location of piezoelectric layer.The time domain response are solved to verify the optimization result and vibration control.Finally,the dynamic model of piezoelectric laminated shell is established,in which,considering geometric nonlinearity.The differential equation of motion is solved by Incremental Harmonic Balance Method,and the vibration control of the piezoelectric lamianted shell is verified.The influence of the size and position of the piezoelectric layer on the frequency-amplitude response of the laminated cylindrical shell are studied.