Phenomenological Modeling of the Stress-Stretch Behavior of EPDM Rubber with Loading-rate and Damage Effects

This paper formulates a phenomenological continuum model, which includes the idealized Mullins effect and loading-rate effects, for the stress-stretch behavior of ethylene-propylene-diene terpolymer (EPDM). This proposed model is based on Ogden and Roxburgh’s pseudoelasticity theory and a hyperelastic form of strain-energy function describing the Mullins effect. Based on experimental results, the loading-rate effects are introduced into this model by replacing the material parameters with an exponential formation as a function of loading rate. The loading rate has effects only on the material parameters and the degree of damage in a specimen is only dependent on the maximum stretch ratio it experiences. It is demonstrated that this model provides a good agreement with the experimental results on EPDM stress-stretch behavior over a wide range of stretching rates.