Overload effects on fatigue crack-tip fields under plane stress conditions: surface and bulk analysis
Author
Summary, in English
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.
Department/s
Publishing year
2013
Language
English
Pages
75-84
Publication/Series
Fatigue & Fracture of Engineering Materials & Structures
Volume
36
Issue
1
Links
Document type
Journal article
Publisher
Wiley-Blackwell
Topic
- Physical Sciences
- Natural Sciences
Keywords
- overload effect
- synchrotron X-ray diffraction
Status
Published
ISBN/ISSN/Other
- ISSN: 1460-2695