Methods for Determining the Mode I and Mode II Fracture Toughness of Glass Using Thermal Stresses

Abstract

The fracture toughness of soda-lime glass was measured by applying thermal stresses to center-cracked plates. Mode I cracking was achieved by chilling the crack faces. The stress intensity factor was obtained by combining temperature measurements with a finite element solution. The average value of KIC = 0.77 MN/m3/2 based on three tests agrees well with values in the literature for a water-free environment. Mode II cracking was achieved by applying a temperature gradient normal to the crack. A value KIIC = 1.6 MN/m3/2 was obtained in two tests using a finite element computation based on the temperature distribution computed from the specimen’s thermal boundary conditions.