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Title:Cleavage due to dislocation confinement in layered materials
Author(s):Hsia, K.J.; Suo, Z.; Yang, W
Dislocation Confinement
Layered Materials
Abstract:The effects of dislocation confinement on fracture behavior in laminates consisting of alternating submicron ductile and brittle layers are studied. When the ductile layer thickness is below the micron level, dislocations must be treated individually. Dislocations emitted from the crack tip have two effects: they blunt the crack and thereby reduce the tensile stress at the crack tip; and pile up against an interface and send a back stress to the crack tip to hinder further dislocation emission. Consequently, an equilibrium number of dislocations exist at a given load level. We estimate this number by considering the stability conditions for dislocations threading in the ductile layer, and dislocation pile-up is treated as an equivalent superdislocation. Furthermore, the competition between further dislocation emission and cleavage at the blunted crack tip is considered. Our result shows that because of the confinement, as the applied load increases, the tensile stress at the blunted crack also increases. Cleavage occurs when the tensile stress at the crack tip reaches the theoretical strength. Given a sufficiently thin constraining layer, cleavage can even occur in ductile metals such as copper and aluminum. The implications of this model for several material systems are discussed.
Issue Date:1993-10
Publisher:Department of Theoretical and Applied Mechanics. College of Engineering. University of Illinois at Urbana-Champaign
Series/Report:TAM R 730
Genre:Technical Report
Sponsor:National Science Foundation 93/10; Office of Naval Research 93/10
Rights Information:Copyright 1993 Board of Trustees of the University of Illinois
Date Available in IDEALS:2021-11-04

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  • Technical Reports - Theoretical and Applied Mechanics (TAM)
    TAM technical reports include manuscripts intended for publication, theses judged to have general interest, notes prepared for short courses, symposia compiled from outstanding undergraduate projects, and reports prepared for research-sponsoring agencies.

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