MODE I AND MIXED-MODE STABLE CRACK EXTENSIONS THROUGH STIFFENED THREE-POINT BEND SPECIMENS

Abstract Both experimental and theoretical results on stable crack extensions are presented for symmetrically stiffened and unstiffened three point bend specimens subjected to mode I or mixed mode loading systems. Results concerning load-displacement variation, growth of plastic zones, instantaneous crack edge profiles, tunnelling, etc., are presented. There is good agreement between the experimental and theoretical results. The whole of stable crack growth can be characterized by the crack opening angle criterion. The stiffening helps to increase substantially both the initiation load and the maximum fracture load.