Experimental and numerical study of ball size effect on restitution coefficient in low velocity impacts

In this article, the Coefficient of Restitution (COR) and Energy Loss Percentage (ELP) of one-dimensional impacts are determined experimentally for different ball sizes using a drop test apparatus. Ball diameters range from 6 to 12 mm, made of steel and aluminum dropped on steel and aluminum sheets. Furthermore, effects of ball sizes on COR and contact time duration are studied numerically. In addition, time variation of displacement of the midpoint of sheet’s top surface and vibration of the ball’s center are investigated. This is done using a finite element model for elasto-plastic collisions. In this work, dynamic and explicit analyses have been carried out by using the LS-DYNA module of ANSYS. The numerical results are validated by the present experimental data. Moreover, the present results are compared with previous works. Results show that COR decreases as balls’ diameters increase.