Deformation parameters of separation failure in tension and compression

Abstract

The results are presented of experimental examination of the displacement of the edges of a separation crack in brittle (silicated glass) and quasi-brittle (polymethyl methacrylate) materials deformed in uniaxial static loading in tension, compression, and bending (eccentric tension). The results of analysis of these data are used to introduce the new interpretation of various basic concepts, such as the end region of the crack d, opening displacement δ1 and the crack tip opening α1. It is attempted to obtain values of the strain parameters d, δ1 α1, invariant to the method of determination. These values correspond to the start of crack propagation in the examined materials. It is shown that the quantities δIi in brittle failure and αIi in quasi-brittle failure are relatively independent of the type of tested specimen.