Effects of material strain rate sensitivity in low speed impact between two identical spheres

This paper investigates the effects of strain rate sensitivity on the impact of two identical spheres. The spheres made of SUJ2 steel were impacted by using pendulum setup. The coefficients of restitution (COR) and contact durations were obtained experimentally. Static tensile test and Split Hopkinson pressure bar tests were conducted to identify the material properties of the sphere. And finite element simulations of the impacts between two identical spheres were carried out using LS-DYNA software. The simulation results fit well to the experimental results and they were compared to the results of elasto-plastic simulations which ignored the material strain rate sensitivity. It was found that the strain rate sensitive sphere showed the higher COR than those from the sphere which ignored the material strain rate sensitivity. Therefore, the material strain rate sensitivity has remarkable effect on the impact of two identical spheres even in the low speed impact. However, the influences of the material strain rate sensitivity on the contact durations were small.