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 quasi-brittle 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, , 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.