Dynamic mechanical response of polystyrene at high strain rates under uniaxial strain ramp loading

Determination of the yield strength of polymers under dynamic loading has proven to be extremely difficult. Until now, few strength data have been obtained for polymers at strain rates above 10⁵ s⁻¹. Based on the electromagnetically driven quasi-isentropic loading technique, the yield strength of polystyrene under high pressure and high strain rate is measured experimentally using a pressure comparison method. In the experiment, a polystyrene window method is used to measure the in-situ particle velocity directly, which reduces the experimental error and obtains reliable high-pressure Lagrangian sound velocity and a quasi-isentropic compression line. The yield stress of polystyrene under quasi-isentropic compression is measured continuously at pressure up to 4 GPa and a strain rate of 10⁶ s⁻¹. Combined with strength data under quasi-static and intermediate strain rate loading, the strain rate effect of the yield of polystyrene is analyzed. It is found that the yield strength of polystyrene shows strain rate effects, but the “up-turn” phenomenon is not observed. Additionally, the yield stress of polystyrene from 10⁻³ s⁻¹ to 10⁶ s⁻¹ strain rate can be fitted using the Eyring model, which provides a reference for the study of the physical properties of polymer materials under high strain rate loading.