EFFECT OF CRACK BLUNTING ON SUBSEQUENT CRACK PROPAGATION
Department of Physics, Washington University, St. Louis,
MO 63130-4899
and ROBB
THOMSON
National Institute of Standards and Technology, Gaithersburg,
MD 20899
Abstract
Theories of toughness of materials depend on an understanding of the
characteristic instabilities of the crack tip, and their possible
interactions. In this paper we examine the effect of dislocation
emission on subsequent cleavage of a crack and on further dislocation
emission. The work is an extension of the previously published
Lattice Greens Function methodology. We have developed a Cavity
Greens Function describing a blunt crack and used it to study the
effect of crack blunting under a range of different force laws. As
the crack is blunted, we find a small but noticeable increase in the
crack loading needed to propagate the crack. This effect may be of
importance in materials where a dislocation source near the crack tip
in a brittle material causes the crack to absorb anti-shielding
dislocations, and thus cause a blunting of the crack. It is obviously
also relevant to cracks in more ductile materials where the crack
itself may emit dislocations.
Published in Mat. Res. Soc. Symp. Proc. 409, 95 (1995).
This paper was presented at the Materials Research Society's 1995 Fall
Meeting.
A preprint is available as compressed
PostScript (8 pages, 39 kB compressed, 140 kB uncompressed)
Also available from the Los Alamos preprint server as document cond-mat/9512041.
Last modified: September 19, 1996, email etc corrected June 2, 2003.
Jakob Schiøtz,
schiotz@fysik.dtu.dk