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On the role of anisotropic expansion and yield stress on crack tip precipitates

Reheman, Wureguli and Ståhle, Per LU (2019) In Theoretical and Applied Fracture Mechanics 103.
Abstract

This pilot study uses a Landau-Lifshitz phase field model to study the growth of a precipitate originating from a crack tip. A boundary layer giving a remote square root singular elastic stress field is applied. The materials are assumed to be elastic-plastic with linear strain hardening. The precipitate is assumed to expand in a simplified anisotropic manner, meaning that the hydride is assumed to grow with an orientation giving maximum expansion perpendicular to the crack plane. The results show that the anisotropic expansion has a strong effect on the shape of the hydride. For anisotropic materials the hydride becomes wedge like. The resulting shapes for the anisotropic cases are in line with observations of internal crack tip... (More)

This pilot study uses a Landau-Lifshitz phase field model to study the growth of a precipitate originating from a crack tip. A boundary layer giving a remote square root singular elastic stress field is applied. The materials are assumed to be elastic-plastic with linear strain hardening. The precipitate is assumed to expand in a simplified anisotropic manner, meaning that the hydride is assumed to grow with an orientation giving maximum expansion perpendicular to the crack plane. The results show that the anisotropic expansion has a strong effect on the shape of the hydride. For anisotropic materials the hydride becomes wedge like. The resulting shapes for the anisotropic cases are in line with observations of internal crack tip hydrides in zirconium. The shapes resemble earlier results for Einstein-Smoluchowski stress driven diffusion using discrete models and simplified modelling of the growth process. The crack tip shielding caused by both precipitation and plastic yielding is examined using the J integral. It shows that the near tip value is a around a quarter of its remote value for elastic isotropic materials and around a half for anisotropic materials.

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type
Contribution to journal
publication status
published
subject
keywords
Anisotropic, Crack, Hydride, Phase field, Plastic, Precipitate, Stress driven diffusion
in
Theoretical and Applied Fracture Mechanics
volume
103
article number
102290
publisher
Elsevier
external identifiers
  • scopus:85069437532
ISSN
0167-8442
DOI
10.1016/j.tafmec.2019.102290
language
English
LU publication?
yes
id
6142f601-864d-4657-a2e9-76522b62a8fe
date added to LUP
2019-08-02 08:52:54
date last changed
2022-04-26 03:47:13
@article{6142f601-864d-4657-a2e9-76522b62a8fe,
  abstract     = {{<p>This pilot study uses a Landau-Lifshitz phase field model to study the growth of a precipitate originating from a crack tip. A boundary layer giving a remote square root singular elastic stress field is applied. The materials are assumed to be elastic-plastic with linear strain hardening. The precipitate is assumed to expand in a simplified anisotropic manner, meaning that the hydride is assumed to grow with an orientation giving maximum expansion perpendicular to the crack plane. The results show that the anisotropic expansion has a strong effect on the shape of the hydride. For anisotropic materials the hydride becomes wedge like. The resulting shapes for the anisotropic cases are in line with observations of internal crack tip hydrides in zirconium. The shapes resemble earlier results for Einstein-Smoluchowski stress driven diffusion using discrete models and simplified modelling of the growth process. The crack tip shielding caused by both precipitation and plastic yielding is examined using the J integral. It shows that the near tip value is a around a quarter of its remote value for elastic isotropic materials and around a half for anisotropic materials.</p>}},
  author       = {{Reheman, Wureguli and Ståhle, Per}},
  issn         = {{0167-8442}},
  keywords     = {{Anisotropic; Crack; Hydride; Phase field; Plastic; Precipitate; Stress driven diffusion}},
  language     = {{eng}},
  month        = {{10}},
  publisher    = {{Elsevier}},
  series       = {{Theoretical and Applied Fracture Mechanics}},
  title        = {{On the role of anisotropic expansion and yield stress on crack tip precipitates}},
  url          = {{http://dx.doi.org/10.1016/j.tafmec.2019.102290}},
  doi          = {{10.1016/j.tafmec.2019.102290}},
  volume       = {{103}},
  year         = {{2019}},
}