Experimental Investigation of Crack Path Directional Stability

摘要

Using the criterion that a crack will extend perpendicular to the maximum circumferential stress, it is shown that the directional stability of crack growth is governed by the location of micro-crack initiation ahead of the crack tip. At distances greater than a geometrical radius r sub 0 the maximum value of sigma/sub theta/ deviates from the position of symmetry. Thus, if it is assumed that the physical processes involved in fracture lead to crack initiation at a distance r/sub c/ ahead of the crack tip, the criterion for directional stability is r sub 0 > r/sub c/. Experimental and theoretical values of r sub 0 verify that as r sub 0 becomes small, the crack's directional stability deteriorates. (ERA citation 04:043404)