A COMPARISON OF DAMAGE IN GLASS AND CERAMIC TARGETS

The high strength and low density of many ceramics and the transparency and low cost of glasses make them potentially useful candidates for many applications, including armor. Both ceramics and glasses are very brittle and they can go through a complex fracture process when impacted. Ballistic impacts on ceramics produce different types of damage including varying levels of comminution, cone cracking, and radial cracking. Sphere impacts on brittle targets are a useful way to study the evolution of ceramic damage. We performed sphere impact experiments on fused silica glass targets. This work is compared with X-ray computed tomography scans of recovered samples generated from previous work on boron carbide [B. Aydelotte and B. Schuster, in Dynamic Behavior of Materials, Volume 1, Springer International Publishing, 2016, pp. 19-23]. The damage morphologies of the sphere impacted fused silica and boron carbide targets are compared. We found that cone cracks in boron carbide and fused silica have the same general shape in response to temporally and spatially changing loads and appear to exhibit cone rotation that is related to the component of the velocity tangential to the target surface. Cone angles in boron carbide were larger when measured in a plane which contains the shot-line vector and intersects the apex of the fracture conoid. Measurements of the fracture cone angle on a plane perpendicular to the plane containing the shot-line vector were consistently smaller for the same velocity. Measurements of cone angles in fused silica exhibited no such trends.