Fracture mechanics analysis of thermally tempered glass plate: fracture induced by an embedded crack

This paper presents a fracture mechanics analysis of a thermally tempered glass plate. The fracture is induced by an embedded penny-shaped crack. The analysis shows that the existence of a penny-shaped crack will reduce the strength of tempered glass. The impact and fatigue resistance of the glass is related to the position and size of the penny-shaped crack. When the tempering intensity reached to a certain level, thermally tempered glass with a penny-shaped crack could experience spontaneous fracture. The damage of a central crack on glass is more severe than a surface crack. With surface compression, thermal tempering will increase the critical applied stress of the glass if the surface penny-shaped crack size is in the range of 0 < a/d < 0.27, where a is the crack size, d is the half thickness of the glass plate. For a small surface crack with the size of a/d 0.09, the tempering can hinder its extension. However, if there is a central penny-shaped crack, the critical applied stress of the tempered glass will decrease with the intensity of tempering.*Author for correspondence. (E-mail: lejun@mail.sic.ac.cn)     

The fracture behaviour of a welded tubular joint: an ESIS round robin on failure assessment methods: Part V: screening method by required toughness and plastic stability considerations

A simplified failure assessment method, which is meant to be appropriate for a first screening of the considered structure with respect to its defect sensitivity, is applied to the T-joint of the ESIS round robin [Fracture behaviour of a welded tubular joint--round robin on failure assessment methods, First Information Package GKSS, 1994; Proceedings of 10th European Conference on Fracture, Berlin, vol. 1, 1994, p. 787]. The method enables one to identify fracture critical parts and to predict roughly the behaviour of a crack-like defect. It consists of an overall required toughness criterion to predict whether or not cleavage fracture can be initiated by a surface crack, and of a simplified stability analysis of the subsequent tearing process. This information can provide the basis to decide whether or not a more detailed failure assessment is required. Combined with analytical calculations of the overall plastic limit loads, the loading and fracture behaviour of the T-joint could be predicted by this simple and cost-effective method with reasonably good accuracy.