The evolution of crack-tip stresses during a fatigue overload event

A. Steuwer, M. Rahman, A. Shterenlikht, M. E. Fitzpatrick, L. Edwards, P. J. Withers

Research output: Contribution to journalArticle

53 Citations (Scopus)

Abstract

The mechanisms responsible for the transient retardation or acceleration of fatigue crack growth subsequent to overloading are a matter of intense debate. Plasticity-induced closure and residual stresses have often been invoked to explain these phenomena, but closure mechanisms are disputed, especially under conditions approximating to generalised plane strain. In this paper we exploit synchrotron radiation to report very high spatial resolution two-dimensional elastic strain and stress maps at maximum and minimum loading measured under plane strain during a normal fatigue cycle, as well as during and after a 100% overload event, in ultra-fine grained AA5091 aluminium alloy. These observations provide direct evidence of the material stress state in the vicinity of the crack-tip in thick samples. Significant compressive residual stresses were found both in front of and behind the crack-tip immediately following the overload event. The effective stress intensity at the crack-tip was determined directly from the local stress field measured deep within the bulk (plane strain) by comparison with linear elastic fracture mechanical theory. This agrees well with that nominally applied at maximum load and 100% overload. After overload, however, the stress fields were not well described by classical K fields due to closure-related residual stresses. Little evidence of overload closure was observed sometime after the overload event, in our case possibly because the overload plastic zone was very small. Crown

Original languageEnglish
Pages (from-to)4039-4052
Number of pages14
JournalActa Materialia
Volume58
Issue number11
Early online date10 Apr 2010
DOIs
Publication statusPublished - Jun 2010
Externally publishedYes

Fingerprint

Crack tips
Fatigue of materials
Residual stresses
Synchrotron radiation
Fatigue crack propagation
Compressive stress
Plasticity
Aluminum alloys
Plastics

Keywords

  • Crack-tip stress field
  • Overload
  • Plasticity-induced closure
  • Retardation
  • Stress intensity factor

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

Cite this

Steuwer, A., Rahman, M., Shterenlikht, A., Fitzpatrick, M. E., Edwards, L., & Withers, P. J. (2010). The evolution of crack-tip stresses during a fatigue overload event. Acta Materialia, 58(11), 4039-4052. https://doi.org/10.1016/j.actamat.2010.03.013

The evolution of crack-tip stresses during a fatigue overload event. / Steuwer, A.; Rahman, M.; Shterenlikht, A.; Fitzpatrick, M. E.; Edwards, L.; Withers, P. J.

In: Acta Materialia, Vol. 58, No. 11, 06.2010, p. 4039-4052.

Research output: Contribution to journalArticle

Steuwer, A, Rahman, M, Shterenlikht, A, Fitzpatrick, ME, Edwards, L & Withers, PJ 2010, 'The evolution of crack-tip stresses during a fatigue overload event' Acta Materialia, vol. 58, no. 11, pp. 4039-4052. https://doi.org/10.1016/j.actamat.2010.03.013
Steuwer, A. ; Rahman, M. ; Shterenlikht, A. ; Fitzpatrick, M. E. ; Edwards, L. ; Withers, P. J. / The evolution of crack-tip stresses during a fatigue overload event. In: Acta Materialia. 2010 ; Vol. 58, No. 11. pp. 4039-4052.
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