Fatigue Crack Growth Fundamentals in Shape Memory Alloys

Y. Wu, A. Ojha, L. Patriarca, H. Sehitoglu

Research output: Contribution to journalArticlepeer-review

Abstract

In this study, based on a regression of the crack tip displacements, the stress intensity range in fatigue is quantitatively determined for the shape memory alloy Ni2FeGa. The results are compared to the calculated stress intensity ranges with a micro-mechanical analysis accounting for the transformation-induced tractions. The effective stress intensity ranges obtained with both methods are in close agreement. Also, the fatigue crack closure levels were measured as 30 % of the maximum load using virtual extensometers along the crack flanks. This result is also in close agreement with the regression and micro-mechanical modeling findings. The current work pointed to the importance of elastic moduli changes and the residual transformation strains playing a role in the fatigue crack growth behavior. Additional simulations are conducted for two other important shape memory alloys, NiTi and CuZnAl, where the reductions in stress intensity range were found to be lower than Ni2FeGa.

Original languageEnglish (US)
Pages (from-to)18-40
Number of pages23
JournalShape Memory and Superelasticity
Volume1
Issue number1
DOIs
StatePublished - Mar 1 2015

Keywords

  • Effective stress intensity range
  • Fatigue crack growth
  • Pseudoelasticity
  • Shape memory
  • Threshold stress intensity
  • Transformation strain

ASJC Scopus subject areas

  • Mechanics of Materials
  • Materials Science(all)

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