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A Viscoelastic Constitutive Model for the Creep Response of Polyurethane Rubber



V Rouiller, G B. McKenna


A viscoelastic model is developed to describe the behavior of a polyurethane rubber provided to NIST by NSWC, Carderock. The model is based on concepts of time-dependent rubber elasticity and single integral models of viscoelasticity. The strain energy density function is assumed to be of a Valanis-Landel form, while its time-dependence is analyzed using the perfect elastic fluid model of Bernstein, Kearsley and Zapas. In addition, time-strain separability and time-temperature superposition are assumed to apply to the polyurethane in the temperature range of interest. Single step stress relaxation experiments in uniaxial extension are used to determine the model parameters. From these, multiple step stress relaxation and creep histories are applied to the material and it is found that the model can describe the nonlinear time-dependent viscoelastic response of the polyurethane resin to these cyclic histories to within approximately 10% of the maximum load or deformation value applied.
NIST Interagency/Internal Report (NISTIR) - 6177
Report Number


creep, PEN, relaxation process, time-aging time superposition, viscoelasticity


Rouiller, V. and McKenna, G. (1998), A Viscoelastic Constitutive Model for the Creep Response of Polyurethane Rubber, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD (Accessed April 22, 2024)
Created August 1, 1998, Updated October 16, 2008