Organizers of the Glass & Optical Materials Division’s 2011 meeting invited veteran materials engineer Richard C. Bradt to address the topic of glass strength. Bradt, the Alton N. Scott Professor Emeritus, Department of Metallurgical and Materials Engineering, University of Alabama, covers a lot of territory in a presentation he entitled, ”A fracture mechanics view of the practical strength of glass.”
Bradt, an ACerS fellow, explains the value of a fracture mechanics approach and explores the various terms contained in the Griffith Equation. The failure criterion, after Griffith, is presented in a fracture mechanics format (in terms of the fracture toughness, the applied stress and the flaw size).
Using anecdotes and fracture mechanic concepts, Bradt ultimately explains what practical steps can be employed — separately and collectively — to make glass stronger for practical uses, including the effects of composition modification, slowing crack growth and the use of residual stress, such as heat strengthening, thermal and chemical tempering.