Experimental study of oblique impacts with initial spin

An experiment to measure the properties of the impacts between of a 44.5 mm steel ball and a steel flat surface is reported. The apparatus can release the ball with and without initial spin. The steel target can be inclined 0-60 degrees. The impact event is recorded with a digital video camera. The video analysis is computer based and all the distortions of image are calibrated. The impact properties measured are expressed as coefficient of normal restitution e(n), coefficient of tangential restitution e(t), impulse ratio or dynamic coefficient of friction f, angular velocity, and rebound angle of the contact point. It is found that the measurement of oblique impact without initial spin shows close agreement with recent published results and complies with rigid body theory. However, the experimental results of oblique impact with pre-impact spin do not agree to the collision models in rolling or micro-slip regime in particular. (c) 2005 Elsevier B.V. All rights reserved.