Crack Tip Dislocations and its Shielding Effect
Two dimensional simulations of discrete dislocation dynamics were carried out to clarify a shielding effect due to dislocations at a crack tip. The configuration of dislocations around the crack tip was calculated under the conditions of mode I tensile load at high temperatures. The stress field around the crack tip due to dislocations was found to be compressive, accommodating mode I stress intensity at the crack tip. In order to experimentally confirm the stress accommodation, infrared photoelastic observation was also performed in a specimen pre-deformed at high temperatures. The experimental result is in good agreement with a simulated infrared photoelastic image derived from the stress field calculated.
Young Won Chang, Nack J. Kim and Chong Soo Lee
M. Tanaka et al., "Crack Tip Dislocations and its Shielding Effect", Materials Science Forum, Vols. 561-565, pp. 1833-1836, 2007