Plastic flow in glass

Abstract

The classical brittle fracture mechanisms fail to account for the mechanical properties of glasses, but the widespread evidence of plastic flow in all glass fracture phenomena even at room temperature suggests that this flow might provide a consistent glass strength theory. This first paper discusses the evidence for flow, evaluates the flow stresses by re-interpretation of the indentation hardness figures, and shows that the flow stresses are much lower than the theoretical cohesive strengths.