The Research Of Visco-hyperelastic Constitutive Model For Rubber Materials

Rubber materials is a typical visco-hyperelasticity composite,its mechanical behaviors show strain dependence,frequency dependence and loading history dependence deeply,furthermore,due to the physical non-linear property and geometric nonlinear property of rubber materials,makes the rubber constitutive particularly complex.None of constitutive model could describe the rubber mechanical properties accurately in the field of rubber products design at present time.In this thesis,we mainly studied the hyperelastic constitutive,visco-hyperelastic constitutive models of rubber.The main works and achievements are listed as follows.1.The constitutive model of rubber material,the current state of rubber constitutive model research and the influence factors of viscoelastic behaviors of rubber material such as strain temperature and frequency were briefly reviewed.2.The related experiments of rubber material mainly include two parts:the first part is static(quasi-static)experiments,and the second part is dynamic experiments.The static experiments contain loading and unloading test and stress relaxation test and so on,the dynamic experiments contain dynamic sweep strain test and dynamic sweep temperature test.The mechanical experiments above,on the one hand,was used to analyses the results of rubber mechanical properties test and by this way show the characteristics of the visco-hyperelastic behaviors of rubber material,on the other hand,was used to provide the experimental basis for the following constitutive model research.3.In the research of hyperelastic constitutive model,the fitting performance of different types constitutive model was discussed firstly that the test data derived from the three-basic mechanical test of uniaxial tension(UT)planar tension(PT)and equibiaxial tension(ET).Second,A hybrid hyperelastic constitutive model was proposed under statistical theory,the constitutive model was composed of Gaussian network model and non-Gaussian network model,which combined by compounding nonlinear function,the Gaussian network model was applied to describe the Gaussian deformation part,and the non-Gaussian network model was applied to describe the non-Gaussian deformation part.An efficient verified was made by test data and Treloar's data,indicating that the hybrid hyperelastic constitutive model is reliable and reasonable.UHYPER subroutine of the hybrid model was developed based on the Fortran language and coding rules.4.In the research of viscoelastic constitutive model,modified Zener model was developed firstly based on the shortage of traditional mechanical model.The classic Zener model was composed of linear spring and linear Maxwell model,while the modified Zener model was composed of nonlinear spring and nonlinear Maxwell model.Second,based on the modified Zener model,two visco-hyperelastic constitutive models were proposed.One model was based on the rate-form,the other model was based on the first strain invariant.Two visco-hyperelastic model all divided stress into hyperelastic stress and viscoelastic stress,comparison between simulation and test data was made to confirm reliability of the proposed constitutive model.