PAPER 16 - A general discussion of short crack fracture

Abstract

This paper discusses experimental and analytical techniques for characterizing plastic strain around crack tips from deep to short crack depths. Numerically derived load deflections and plastic strain patterns for single edge notched bend bars, fabricated from ASTM A710 Grade A plate, are compared with experimental measurements. The shapes of the plastic zones are experimentally characterized employing visual techniques. Experimental trends in J and stretch zone width as crack depth is varied from the deep to short crack depth are described. Stretch zone width measurements between 0.08 a/W and 0.95 a/W have shown that there is no observable difference in stretch zone width between the deep and shallow notched specimens. This work indicates that a well defined plastic strain pattern develops around the crack, which precedes stable crack growth.