Compressive Properties and Constitutive Model of Semicrystalline Polyethylene

The mechanical properties of polyethylene (PE) materials are greatly influenced by their molecular structures, environmental temperature, and strain rate. In this study, static and dynamic compression tests were performed on two semicrystalline PE materials-ultrahigh molecular weight polyethylene (UHMWPE) and high-density polyethylene (HDPE). The stress-strain curves of HDPE and UHMWPE under uniaxial compression at temperatures of -40-120 °C and strain rates of 0.001-5500 s^-1 were obtained. The research findings suggest that both the UHMWPE and HDPE showed significant strain rate-strengthening effect and temperature-softening effect. In particular, HDPE exhibited better compression resistance and high-temperature resistance. The relationships between the yield stress and temperature and between the yield stress and strain rate for both materials were fitted, and the Cowper-Symonds constitutive model was built while considering the temperature effect. The parameters of the constitutive model were obtained and input into LS-DYNA software to simulate the dynamic compression process of HDPE. The simulation result was consistent with the test result, validating the accuracy of the constitutive parameters.