Plane-strain deformation near a slot extended under load: Some observations using grain-orientated 3 1 2per cent silicon-iron

Abstract

Experiments were performed using grain-orientated 3 1 2per cent silicon-iron. Plane-strain deformation can be obtained in thin plates of this material and, also, the plastic deformation that occurs can be revealed by etching. In some experiments the slot was extended while the specimen was under load and the plastic deformation was then observed. The distribution and density of the resulting slip-lines agrees qualitatively with J. R. Rice's (1968) model of the deformation at the tip of a crack growing in a continuum. In Rice's model, irreversible plastic deformation prevents complete focusing of the slip-lines at a crack tip; and in the present work an analogous effect was observed, the major difference being that in the present experiments the slip-lines are fixed by the crystal structure of the material. A qualitative explanation of the observations is given in terms of the interaction that exists between dislocations and a crack. © 1980.