Constitutive modeling of the tensile and compressive deformation behavior of polyurea over a wide range of strain rates

A three-dimensional visco-hyperelastic constitutive model is developed to describe the finite deformation mechanical behavior of polyurea materials at different strain rates. The constitutive model of finite strain visco-hyperelasticity is founded on the basis of the multiplicative decomposition of the deformation gradient tensor into hyperelastic and viscoelastic parts. The hyperelastic part uses the strain energy function to characterize the equilibrium response, and the viscoelastic part capturing the rate sensitivity uses the time partial derivative of strain energy function to characterize the time-dependent response. The nonlinear mechanical responses of the materials under several common loading conditions are calculated by the new proposed constitutive model. In order to validate the effectiveness of the constitutive model, the nonlinear stress-strain behavior of polyurea under uniaxial tension and compression are carried out in this paper. The experimental verification and the error analysis show that the model is capable of accurately representing the finite deformation stress-strain behavior of polyurea over a strain-rate range of 10−3-104/s. In order to further broaden the application of the constitutive model, a method is presented which is available to predict the experimental results of polyurea at quasi-one dimensional strain state.