Study On Mechanical Properties And Constitutive Of Polyurethane Elastomer Under Static/Dynamic Conditions

Polyurethane elastomer(PUE)has been widely used in people's life and industry for its advantages of light weight,energy absorption,abrasion resistance and so on.Polyurethane elastomer is commonly used as energy absorbing component.Therefore,the mechanical properties of polyurethane elastomer are becoming the focus of attention in engineering.In the process of designing,manufacturing and reliability analysis of polyurethane elastomer products,it is necessary to establish a simple and practical constitutive model considering the strain rate and temperature effect.Hence,the following work were conducted based on the method of combining experimental and theoretical analysis:(1)Quasi-static compression experiment and the study on the hyperelastic constitutive of polyurethane elastomer;(2)The establishment and verification of the visco-hyperelastic constitutive for polyurethane elastomer based on the dynamic experimental data;(3)The dynamic compression experiments of polyurethane elastomers under different temperature conditions were carried out to establish the corresponding thermo-visco-hyperelastic constitutive model.Uniaxial compression experiments were carried out for polyurethane elastomer under the strain rate of 10-3/s,10-2/s and 10-1/s.It can be seen that all the experimental curves included the initial linear phase,the nonlinear transformation stage of medium strain and the hardening stage under the condition of large strain.The strain-stress curves under quasi-static conditions exhibited a certain strain rate sensitivity.Six kinds of hyperelastic constitutive models were adopted to fit the experimental curves.Then the relationship between the forms of the energy density functions and their accuracy for experimental curves was discussed.As a result,the ?Three Item? model was suitable as the constitutive model of polyurethane elastomer under low loading rate for its advantages of simple structure,few parameters and good fitting accuracy.The dynamic compression experiments for polyurethane elastomer under four kinds of strain rates were carried out by using split Hopkinson pressure bar.And the experimental curves exhibited a high degree of nonlinearity and strain rate sensitivity.The classical nonlinear ZWT viscoelastic constitutive model was used to fit the experimental curves.It was found that the fitting and prediction accuracy for experimental curves was low,so it was not suitable to be used as the constitutive model of polyurethane elastomer under high strain rate.In this paper,a simple and independent of the strain history visco-hyperelastic model was proposed based on the ?Three Item? model and viscoelasticity mechanics method.The new constitutive model was verified and exhibited better accuracy than ZWT constitutive model.The strain-stress curves of polyurethane elastomer under four kinds of temperature(283K,308 K,333K and 353K)were obtained by using the Hopkinson pressure bar with temperature controlling device.The experimental results showed that the mechanical properties of polyurethane elastomers were greatly affected by temperature.In this paper,a simple thermo-viscoelastic-hyperelastic constitutive was obtained based on the newly established viscoelastic-hyperelastic constitutive model,which provided theoretical and data support for the engineering application of polyurethane elastomer.