Influence of the load conditions on the failure wave in glasses

Abstract

Previously, a series of plate impact experiments have provided evidence for the appearance of failure waves in glasses under uniaxial compression. Presented herein is a continuation of research, performed on K9 crown glass and ZF1 dense flint glass at varied shock stresses with a goal to uncover the failure wave source and to make clear whether or not the failure wave can be formed at stresses above the Hugoniot elastic limit (HEL). It has been found that, at peak stresses below the HEL, the failure wave can be initiated on both the impact surface and the internal surface inside the sample, indicating that the glass surface is a direct source for the failure wave nucleation. However, when the peak stress exceeds the HEL, brittle glasses become ductile as a result of irreversible densification, and the Failure wave disappears. The high spall strength revealed in the stress range above the HEL indicates that ductility is also preserved under the subsequent tension.