Shape transformation of a wake following the process zone at the tip of a propagating crack

Abstract

A process zone containing a new phase often forms at the tip of a crack in a quasibrittle solid. We study such a zone engendered by the propagating crack. We show that depending on the crack speed, V , this zone has two distinct configurations. If the crack tip velocity is small, the zone takes a concave shape. As soon as V exceeds a critical value, VG, the zone becomes convex. A metastable remnant, the wake, forms in its rear part. It is stretched backward over a great distance and exhibits a triangle configuration with the vertex angle decreasing with speed. The morphological zone transition and the wake shape is explained by competition of the velocity of a free, plane phase front and the crack tip speed.