COMPARISON BETWEEN STANDARD FRACTURE-TOUGHNESS RESULTS AND SURFACE FLAW DATA FOR SILICON-CARBIDE

Stress intensity factors were measured for single-edge notched silicon carbide specimens subjected to three-point bending. These data are compared with experimental results from surface flawed specimens subjected to three-point bending. Surface flawed specimens were tested since they resemble defects in structures more closely than any other specimen. The ability to estimate failure conditions for a structural component using measurements of fracture toughness and appropriate equations was evaluated. In many of these tests, acoustic emission and moire interferometry techniques provided valuable information on the crack growth process, constitutive damage zone propagation, and the critical stress intensity factors.