Substrate Deformation Studies by Photoelasticity in Single Particle Impacts

Dynamic photoelasticity methods have been used to study the substrate deformation in polyurethane rubber due to the impact of a 3 mm steel ball with a velocity of 50 m/s and at angles of 30° and 90 ° . The experimental set-up used a multiple-spark camera with an integral polariscope to visualize the dynamic stress field generated by the impact. The stress fields were photographed both in the plane of the impact as well as below it. The analysis of the data showed that the rate of propagation of the stress field was 198 m/s. A maximum strain rate of 2.86 x 10 ³ m/s was determined after a small time following the impact which also coincided with the time of maximum indentation.