Influence of Temperature on Hyperelastic Mechanical Behavior of Accelerated Aged EPDM Rubber

EPDM (Ethylene Propylene Diene Monomer) rubber is a crucial engineering material, and its mechanical behavior changes with aging duration and ambient temperature. The effects of temperature on the hyperelastic behavior of unaged and aged EPDM rubber are investigated by conducting accelerated aging tests under constant compression and uniaxial compression tests at different temperatures. The experimental results show that prolonged aging induces EPDM rubber to exhibit an approximately linear hardening trend under a constant temperature. For aged EPDM rubber, its stiffness initially decreases and then increases with test temperature. The stress hardening factor was introduced to characterize the influence of the test temperature on the aging effect. The factor exhibits a decreasing trend and then an increasing trend with respect to compression test temperature. The curve of the stress hardening factor versus temperature is approximately a quadratic function. To fit the results, a Neo-Hooke model, a Mooney-Rivlin model, and an improved Mooney-Rivlin model were tested for their fit with the EPDM rubber compression data, covering different experimental conditions. The improved Mooney-Rivlin model had the most consistent results with the experimental data. Based on the experimental results, the parameters of the improved Mooney-Rivlin model were extended to model the effects of temperature and aging time. The proposed constitutive model can effectively describe the hyperelastic behavior of aged EPDM rubber tested at different temperatures.