Study On Vibration Characteristics Of Axially Moving Immersed In Fluid

At present,the vibration problem of axially moving plate immersed in fluid has been widely concerned by academia.In engineering practice,there are many structures similar to plates moving in the fluid,such as continuous hot dip galvanized steel strip,conveyor belt through the fluid,paper under the fan,etc.Due to the presence of axial speed and fluid,these structures generate unnecessary vibration,reducing the quality of products and the efficiency of industrial production.It is of great practical significance to study axially moving plate immersed in fluid.In this paper,the vibration of axial motion structure is studied.The specific research contents are as follows:At present,most literatures are considering the study of one model.There are few researches considering the comparative analysis of several models.Moreover,the linear model of the axially moving viscoelastic plate immersed in fluid is mainly studied in the existing research work.Few works involve the establishment and analysis of the fluid-structure coupling nonlinear model of the axially moving viscoelastic plate immersed in fluid when the axial speed and tension change,and the application of the support stiffness is also very limited.The vibration characteristics of three typical axially moving structures,such as the beam,the panel,and the plate with two opposite sides simply supported and other two free,are compared and analysed in this paper.Then,considering the influence of fluid,the vibration characteristics of the axially moving plate immersed in fluid were studied by analytical and numerical methods.Specific research contents are as follows:1.the vibration characteristics of three typical structures,containing beam,panel and the plate with two opposite sides simply supported and other two free,are studied.The governing equations of the three models are solved by the complex modal method,and the corresponding natural frequencies and modal functions are obtained.For the plate model,two rigid body displacements and bending-torsional coupled vibration at the free boundary are considered.The variation of the first four order natural frequencies of the three models with the axial speed and the aspect ratio is given by numerical examples.The analytical solutions obtained by the complex mode method are verified by differential quadrature method.In particular,the influences of axial speed,damping coefficient and aspect ratio on frequency are analyzed in the form of three-dimensional diagram,and the influences of different aspect ratio and axial speed on the relative errors of the first natural frequency of panel and beams are emphatically studied.2.the coupling partial differential equation of the nonlinear viscoelastic plate immersed in fluid with variable axial speed and tension is established by assuming that the liquid is inviscid,irrotational,and incompressible ideal fluid and introducing the supporting stiffness of the plate according to the fluid potential function,Bernoulli equation and the corresponding boundary conditions.The partial differential equation obtained is discretized by Galerkin method.Considering the uniform motion of the plate and ignoring the effects of viscoelasticity and nonlinearity,the effects of truncation order,immersion depth,support stiffness,fluid and stiffness of plate on the natural frequency are analyzed.Ignoring the nonlinear effect,the influence of different parameters on the stability region of the first and second harmonic resonance and the combined resonance of the viscoelastic plate immersed in fluid with axial variable motion is studied by means of the average method.3.based on the Galerkin second-order truncation method,the dimensionless governing equation is discretized into second-order ordinary differential equations.The method of multi-scale is developed to study the 3:1 internal resonance of the plate immersed in fluid.The response of time history,phase diagram and spectrum diagram of the system are analyzed.Through the comparative analysis of the analytical method and numerical method of the time-history response graph,the results obtained by method of multi-scale is verified.