Identifying The Mechanical Parameters Of Damping Materials Based On Inverse Method

Hard coating and viscoelastic damping are two important damping materials.Among them,hard coating can maintain the original damping property at high temperature and corrosive environment,and viscoelastic materials have a good damping effect because of its high internal damping.This two damping materials have applied in engineering,and play an important role in inhibiting vibration of structural parts,especially thin-walled structures.In order to apply the above damping materials on structural components,it must be effectively identified the mechanical parameters?storage modulus and loss factor?of damping material.Hard coating have strain-dependent characteristic,while viscoelastic material have frequent-dependent characteristic,which makes effectively identifying these materials mechanical parameters become a challenging task.In this paper,the hard-coating and viscoelastic composite plates as the object,and the inverse method was attempted to identify the mechanical parameters of hard coating and viscoelastic material.The details are as follows:First,the method of identifying the hard-coating mechanical parameters based on frequency domain data was studied.The identification principle as follows:the analytical model of hard-coating composite plate was created in accordance with classical plate theory;The hard-coating composite plate was tested to obtain the resonance frequencies and resonant responses at different excitation amplitude;The matching algorithm based on sensitivity analysis was developed,and the hard coating parameters were effectively identified after two matching calculation.A titanium plate coated with NiCoCrAlY + YSZ hard coating was taken as an example to practice the developed method.The results showed that:on the premise of determined initial value reasonably,and the hard-coating parameters can be quickly converged by the identification algorithm.Then,the method of identifying the hard-coating mechanical parameters based on free vibration decay response was studied.The developed identification principle as follows:The finite element model of hard-coating plate was created;The free vibration decay response of hard coating cantilever plate was tested,and the method of obtained envelope curve,instant resonance frequency and damping method was given;The matching calculation based on sensitivity analysis was implemented.Similarly,the titanium plate coated with NiCoCrAlY +YSZ hard coating was taken as an object to carry out the study.The results show that:the identification process,identifying the hard coating parameters used free vibration decay response,is simple and easy to implement.Next,the method of identifying the viscoelastic material mechanical parameters based on FRF was studied.Considering two damping,the method for calculating viscoelastic composite FRF was deducted;The FRF of viscoelastic composite plate was obtained by hammering test;The response surface method for matching calculation was given.Then,the storage modulus and loss factor of viscoelastic material were identified.The obtained results was compared with that considering material damping,and the results demonstrates the importance of considering two kinds of damping.Finally,the method of identifying the fractional derivative model of viscoelastic material based on sweep frequency response was studied.The method of solving vibration response of viscoelastic composite plate was given,and the idea of identifying viscoelastic material fractional derivative model utilizing segmented sweep response and non-resonant points was proposed.On this basis,the fractional derivative model parameters of ZN₁ viscoelastic material were identified.Compared with identification method based on FRF,this method can identify the viscoelastic material parameters simultaneously by the data of resonant and non-resonant points.In the hard-coating and viscoelastic damping study,it is need to accurate introduce mechanical parameters of damping material into analysis model,and this paper give some methods for identifying hard coating and viscoelastic material parameters.In addition,the identification method developed in this paper is applicable to any structures installed with viscoelastic materials,and this is important for promoting the application of hard-coating and viscoelastic damping technology in engineering.