The static and dynamic fracture of brittle materials

Contains published articles.Bibliography: p. 131-138.Experiments on the behaviour of brittle materials, particularly quartz, during the initial period of loading, at the onset of fracture and during the stage of rapid crack propagation, have been performed in order to gain an insight into some of the fundamental processes of brittle fracture which might prove useful in the solution of practical problems in mining and process operations. Studies have also been conducted into the nature of the damage produced by a diamond stylus sliding on a quartz surface. The results of these studies have been correlated with ancilliary experiments in which the effects of the deformation produced by a sharp indenter and sliding diamond polishing particles on quartz were examined. The geometry of cracks in glass and quartz during the loading stage has been observed by scanning electron microscopy and was found to be approximately elliptical. By making some simple assumptions, an equation has been derived that enables the fracture surface energy to be deduced from shape of the crack and the loading conditions. The brittleness of a material is indicated by the difference between the fracture surface energy and the thermodynamic surface energy of the material. In a perfectly brittle body they are equal. In order to make an accurate comparison with the true surface energy in quartz as calculated from atomic bond energy data, anisotropic elastic theory was used in the evaluation of the fracture surface energy