Extended dislocations around a semi-infinite crack
Journal
Engineering Fracture Mechanics
Journal Volume
54
Journal Issue
3
Pages
395-403
Date Issued
1996
Author(s)
Abstract
The behavior of an extended dislocation near a semi-infinite crack is investigated. The criterion for the determination of equilibrium separation between Shockley partials and the necessary condition for the formation of extended dislocations by dissociation reaction are developed. It is found that the equilibrium separation increases as the extended dislocation gets closer to the crack. If the stacking fault energy is comparable to the critical energy for dissociation in a perfect medium, complete dislocations can dissociate to form extended dislocations near the crack. For an extended edge (or screw) dislocation near a crack, it produces not only the primary shielding/antishielding effect on modes I and II (or mode III) of fracture but the secondary effect on mode III (or modes I and II) of fracture. The shielding/ antishielding effect on fracture is closely related to the stacking fault energy y of materials. With decreasing γ the primary effect decreases, but the opposite for the secondary effect. In addition, if the extended dislocation slips on a plane containing the crack tip and inclined to the crack plane at an angle θ, the maximum shielding effect occurs at about θ = 70° for mode I of fracture and θ = 0 for modes II and III of fracture when the dislocation remains a constant distance from the crack tip. Copyright © 1996 Elsevier Science Ltd.
SDGs
Publisher
Elsevier Ltd
Type
journal article