University of Illinois Urbana-Champaign

Cleavage due to dislocation confinement in layered materials

Hsia, K.J.; Suo, Z.; Yang, W

Permalink

https://hdl.handle.net/2142/112420

Description

Title
Cleavage due to dislocation confinement in layered materials
Author(s)
  • Hsia, K.J.
  • Suo, Z.
  • Yang, W
Issue Date
1993-10
Keyword(s)
  • Cleavage
  • 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.
Publisher
Department of Theoretical and Applied Mechanics. College of Engineering. University of Illinois at Urbana-Champaign
Series/Report Name or Number
  • TAM R 730
  • 1993-6028
ISSN
0073-5264
Type of Resource
text
Language
eng
Permalink
http://hdl.handle.net/2142/112420
Sponsor(s)/Grant Number(s)
National Science Foundation 93/10; Office of Naval Research 93/10
Copyright and License Information
Copyright 1993 Board of Trustees of the University of Illinois

Owning Collections

Technical Reports - Theoretical and Applied Mechanics (TAM) PRIMARY
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.