Shear deformation under pyramidal indentations in soda-lime glass

Abstract

The nature of the flow lines that occur in the deformed zone in soda-lime glass under pyramidal indentations has been investigated. A close examination of the deformed zone shows that the spiral flow lines meet at 110°, instead of the 90° required by the ideal rigid-plastic behaviour. The flow lines are indeed shear faults (of negligible thickness) produced by genuine shear displacements which are apparent at the intersection points of some of the flow lines. Evidence of void or crack formation at the intersection points or along the flow lines is also presented, along with a possible hardening effect from the suppression of slip at the intersection points of the flow lines.