A model emitting dislocation group from crack tip with stress singularity and its application to brittle-ductile transition

Journal Article · Sat May 01 00:00:00 EDT 1993 · Acta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-7151(93)90249-R· OSTI ID:6222379

Yokobori, Toshimitsu A.Jr. ^[1]; Isogai, Takeshi; Yokobori, Takeo ^[2]

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1. Tohoku Univ., Sendai (Japan). Dept. of Mechatronics and Precision Engineering
2. Teikyo Univ., Tochigi (Japan). School of Science and Engineering

Taking into account the stress singularity near the crack tip, computer simulation of dislocation emission and motion has been carried out. A model is proposed in which the source emitting the dislocation group is located near by the crack tip. The numerical method has been used by programming to adjust time increment automatically. By this model and the analytical method, the converged solution has been obtained. The main results are as follows: The region where any dislocation does not exist along the slip plane near the stressed source, namely, dislocation free zone (DFZ) is found to appear. Also it has been found that inverse pile-up of dislocation against the tip of DFZ will appear. The formula is obtained correlating the maximum dislocation density with DFZ length. With increase of stress rate and decrease of the value of [mu]/[tau][sup *][sub 0], the inverse pile-up at the tip of DFZ becomes more significant. Based on these results, a new fracture criterion for brittle fracture is proposed assuming critical local stress requisite within DFZ, where high stress concentration is induced by dynamic inverse pile-up of dislocations.

• OSTI ID: 6222379
• Journal Information: Acta Metallurgica et Materialia; (United States), Journal Name: Acta Metallurgica et Materialia; (United States) Vol. 41:5; ISSN 0956-7151; ISSN AMATEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
360203 -- Ceramics
Cermets
& Refractories-- Mechanical Properties
360603 -- Materials-- Properties
BRITTLENESS
COMPUTERIZED SIMULATION
CRACKS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DISLOCATIONS
FRACTURE PROPERTIES
LINE DEFECTS
MATERIALS
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
SIMULATION
SLIP
STRESSES