Modification of a defect-based fatigue assessment model for Al-Si-Cu cast alloys

Roman Aigner, Martin Leitner, Michael Stoschka, Christian Hannesschläger, Thomas Wabro, Robert Ehart

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


Cast parts usually inherit internal defects such as micro shrinkage pores due to the manufacturing process. In order to assess the fatigue behaviour in both finite-life and long-life fatigue regions, this paper scientifically contributes towards a defect-based fatigue design model. Extensive fatigue and fracture mechanical tests were conducted whereby the crack initiating defect size population was fractographically evaluated. Complementary in situ X-ray computed tomography scans before and during fatigue testing enabled an experimental estimation of the lifetime until crack initiation, acting as a significant input for the fatigue model. A commonly applied fatigue assessment approach introduced by Tiryakioglu was modified by incorporating the long crack threshold value, which additionally enabled the assessment of the fatigue strength in the long-life fatigue regime. The presented design concept was validated utilising the fatigue test results, which revealed a sound agreement between the experiments and the model. Only a minor deviation of up to about five percent in case of long-life fatigue strength and up to about 9% in case of finite-lifetime were determined. Thus, the provided extension of Tiryakioglu's approach supports a unified fatigue strength assessment of cast aluminium alloys in both the finite- and long-life regimes.

Original languageEnglish
Article number2546
Issue number12
Publication statusPublished - 14 Dec 2018


  • Aluminium casting
  • Computed tomography
  • Defects
  • Extreme value statistics
  • Fatigue assessment
  • Statistical distribution


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