A STUDY OF SOLID PARTICLE FAILURE UNDER NORMAL AND OBLIQUE IMPACT

Systematic data is presented on the failure probability of 5.15 mm aluminium oxide spheres over a wide range of impact speed and angle. The high number of tests made, with 100 particles individually tested per data point was necessary to average out the variations in individual particle properties and to make the results consistent. This has enabled very close curve fits to be made to the data, and the parameters from these fits provide a comprehensive and reliable summary of the material performance. The results show that the probability of particle failure varies only slightly from normal impact to about 50 degrees. Detailed examination of damaged particles has identified four primary forms of fracture which are common to normal impact and static compression, These fractures initiate from a subsurface cone of compression damage, and develop along meridian planes. An additional form of fracture found with oblique impact appears to be a result of tangential loading causing enhanced tension in the surface.