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Overload effects on fatigue crack-tip fields under plane stress conditions: surface and bulk analysis

Lopez-Crespo, P.; Withers, P. J.; Yusof, F.; Dai, H.; Steuwer, Axel LU ; Kelleher, J. F. and Buslaps, T. (2013) In Fatigue & Fracture of Engineering Materials & Structures 36(1). p.75-84
Abstract
The surface crack opening displacements are characterised by digital image correlation for a (thin) plane stress 316 stainless steel compact tension sample subjected to an overload event. This supports a traditional plasticity-induced closure interpretation showing a knee in the closure response prior to overload, an absence of closure in the accelerated growth regime followed by accentuated closure in the retardation regime. By contrast, measurement of the mid-thickness elastic strain field behind and ahead of the crack made by synchrotron X-ray diffraction shows no evidence of significant crack face contact stresses behind the crack tip on approaching minimum loading. Rather the changes during loading and overloading can mostly be... (More)
The surface crack opening displacements are characterised by digital image correlation for a (thin) plane stress 316 stainless steel compact tension sample subjected to an overload event. This supports a traditional plasticity-induced closure interpretation showing a knee in the closure response prior to overload, an absence of closure in the accelerated growth regime followed by accentuated closure in the retardation regime. By contrast, measurement of the mid-thickness elastic strain field behind and ahead of the crack made by synchrotron X-ray diffraction shows no evidence of significant crack face contact stresses behind the crack tip on approaching minimum loading. Rather the changes during loading and overloading can mostly be explained by a simple elastic plastic analysis using a value of the yield stress intermediate between the initial yield stress and the UTS. This shows very significant compressive reverse plastic strains ahead of the crack that start to form early during unloading. At the moment it is not clear whether this difference is because of the increasing stress intensity applied as the crack grows, or for some other reason, such as prevention of the crack faces closing mid-thickness due to the reverse plastic zone. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
overload effect, synchrotron X-ray diffraction
in
Fatigue & Fracture of Engineering Materials & Structures
volume
36
issue
1
pages
75 - 84
publisher
Wiley-Blackwell
external identifiers
  • wos:000312455600008
  • scopus:84871025746
ISSN
1460-2695
DOI
10.1111/j.1460-2695.2012.01670.x
language
English
LU publication?
yes
id
bae9b36d-d335-4b30-9564-c5d726025d78 (old id 3400870)
date added to LUP
2013-01-30 09:57:14
date last changed
2019-03-27 01:29:16
@article{bae9b36d-d335-4b30-9564-c5d726025d78,
  abstract     = {The surface crack opening displacements are characterised by digital image correlation for a (thin) plane stress 316 stainless steel compact tension sample subjected to an overload event. This supports a traditional plasticity-induced closure interpretation showing a knee in the closure response prior to overload, an absence of closure in the accelerated growth regime followed by accentuated closure in the retardation regime. By contrast, measurement of the mid-thickness elastic strain field behind and ahead of the crack made by synchrotron X-ray diffraction shows no evidence of significant crack face contact stresses behind the crack tip on approaching minimum loading. Rather the changes during loading and overloading can mostly be explained by a simple elastic plastic analysis using a value of the yield stress intermediate between the initial yield stress and the UTS. This shows very significant compressive reverse plastic strains ahead of the crack that start to form early during unloading. At the moment it is not clear whether this difference is because of the increasing stress intensity applied as the crack grows, or for some other reason, such as prevention of the crack faces closing mid-thickness due to the reverse plastic zone.},
  author       = {Lopez-Crespo, P. and Withers, P. J. and Yusof, F. and Dai, H. and Steuwer, Axel and Kelleher, J. F. and Buslaps, T.},
  issn         = {1460-2695},
  keyword      = {overload effect,synchrotron X-ray diffraction},
  language     = {eng},
  number       = {1},
  pages        = {75--84},
  publisher    = {Wiley-Blackwell},
  series       = {Fatigue & Fracture of Engineering Materials & Structures},
  title        = {Overload effects on fatigue crack-tip fields under plane stress conditions: surface and bulk analysis},
  url          = {http://dx.doi.org/10.1111/j.1460-2695.2012.01670.x},
  volume       = {36},
  year         = {2013},
}