Experimental analysis of specific energy with variable deformation volume under sphere oblique impact

Abstract

Experiments of a steel sphere oblique impact with a rubber cushion have been proceeded to research the variation laws of the specific energy at interface. The contact surfaces above and under the rubber cushion can be recorded with a thin carbon paper. The parameters of deformation volume and specific energy are analyzed by the developed formulas in different cases of the impact angle, cushion thickness, drop height and sphere diameter. It is found that the deformation volume and related geometrical sizes decrease approximately exponentially with the impact angle, and the volume of the tangential moving part reaches a maximum at 50° or 60°. The variation laws of the specific energy absorption/dissipation in normal are similar to that of the axis length. The tangential specific energy can be divided into three main phases, the first two appear the states of slow increase and plateau, between of them a fluctuating peak exists at 30–40°. In final phase, the energy absorption shows sharp increase, but the energy dissipation first increases and then decreases. In addition, they increase linearly with the drop height and sphere diameter, and an optimum cushion thickness of 4 or 5 mm in the given cases.