Research On Establishment And Application Of Model Of Damping Mechanism For The Hard-coating Thin Shell Component

Hard coating could reduce the vibration response of the thin shell structure in the high temperature and high corrosive environment,thus,it attracts more and more attention.In order to implement the vibration damping of hard coating,the vibration reduction mechanism of hard coating need to be obtained,that is,the reason of vibration response reduction,and then the optimization design of vibration reduction used hard coating can be executed.Now,most of the existing studies on vibration reduction mechanism of hard coating come from micro material science.And most of scholars reckon the internal friction between hard coating micro particles is the reason that hard coating could reduce vibration.However,it is not enough to research the damping mechanism of hard coating completely based on materials science.It is necessary to create the dynamic models of the hard coating composite structures,and then research the damping mechanism of hard coating from the angle of vibration science.Based on the mechanical characteristics of the hard-coating materials,it is studied here how to model the hard-coating composite structure.The main research contents of this paper are as following:First of all,from the separation of hard coatings damping contribution,method of creating hard coated cantilever composite damping mechanism analysis model was considered.the cantilever beam before and after the coating system,the vibration characteristics experiment is obtained parameters such as natural frequency,damping ratio,vibration response and so on.in the cantilever beam before and after the coating system on the basis of analysis of the energy storage and energy dissipation,sure did get hard coating material damping method.The Oberst beam theory was adopted to create the damping mechanism model of cantilever beam which includes both material and viscous damping.The correctness of analytical model was also verified.And the correctness of model was also verified by experiment.Secondly,based on separating the damping contribution of hard coating,the method of creating the damping mechanism model of cantilever composite plate was studied.The cantilever plates before and after coating were tested and the dynamics characteristics parameters,such as natural frequency,damping ratio,vibration response and so on,were obtained.Moreover,from the analysis of the storage and dissipation energy in the uncoated and coated plate,the damping contribution of hard coating was confirmed.Based on the Lagrange equation,the dynamics model of cantilever composite plate was created considering both material damping of hard coating and viscous damping of thin plate,and the correctness of model was also verified by experiment.Thirdly,the vibration test experiment is carried out by using cylindrical shell before and after hard coating.Natural frequency and resonance response of the cylindrical shell before and after hard coating could be obtained.Then,the modal damping ratio of cylindrical shell before and after hard coating could be acquired by using the amplitude-frequency characteristic curve and the half power bandwidth method.Based on Love thin walled shell theory,linear vibration equation of circular cylindrical shell after hard coating could be obtained,the vibration characteristic equation could be identified by the energy method,and it is solved by the Galerkin method.Based on the Obest theory,the loss factor of coating materials can be introduced and the resonance response of the cylindrical shell after hard coating could be solved by using the beam function model.Fourth,the method of measuring indirectly strain energy of hard coating composite beam was considered by using hard coated cantilever composite damping mechanism analysis model.Based on the analysis of strain energy of the beam before and after coating,the theory and method of identifying the strain energy of the beam before and after coating and Including:testing the resonance displacement response of the beam,the test modal damping;using the model updating technology and experiment match,draw the beam flexural resonance state,identification of strain energy and other steps.using coated MgO +Al2O3 titanium beams before and after the case study,effective for the strain energy,and proved the hard coating on titanium beam damping effect.Finally,Young's modulus,loss factor and the coating thickness and other hard coating parameters on the influence law of cylindrical shell vibration characteristics was considered by using hard coated cylindrical shell composite damping mechanism analysis model.The results showed that:with the young's modulus,thickness of coating increased gradually;the natural frequency of composite cylindrical shell after coating has a certain level of increase and resonance response decreases.As loss factor of the coating increase gradually,the resonant response of hard coating composite cylindrical shell gradually became diminished,but hard coating had no effect on the natural frequency of composite cylindrical shell.This paper can provide reference for the selection and preparation of hard-coating material or further study on the damping mechanism of coating material.And it can also provide the support for the application of hard-coating damping technology in aviation.