S042022 Fractoemission of silica glass normalized by fracture surface area

Abstract

Photon emission was measured during crack extension in silica glass. To detect a location of the crack tip, stripe pattern of Au thin coating was made on both tensile and side surfaces of silica glass specimen. The specimen was fractured by three-point bending test in a vacuum chamber. During fracture, the resistances of those thin coatings were monitored, and also photon emission was measured by photomultiplier tubes in the range of wavelength around 450nm and 650nm. The changes in the resistances showed that the crack ran through the tensile surface first, and then extended into the thickness. The fracture surface area was calculated to normalize the count rates of photon emission. It was revealed that photon emission per unit fracture surface area had a maximum value at the onset of fracture and then monotonously decreased with crack extension.