Crack growth in a range of additively manufactured aerospace structural materials

Athanasios Iliopoulos, Rhys Jones, John Michopoulos, Nam Phan, R. K. Singh Raman

Research output: Contribution to journalArticleResearchpeer-review

43 Citations (Scopus)

Abstract

The aerospace industry is now beginning to adopt Additive Manufacturing (AM), both for new aircraft design and to help improve aircraft availability (aircraft sustainment). However, MIL-STD 1530 highlights that to certify airworthiness, the operational life of the airframe must be determined by a damage tolerance analysis. MIL-STD 1530 also states that in this process, the role of testing is merely to validate or correct the analysis. Consequently, if AM-produced parts are to be used as load-carrying members, it is important that the da/dN versus ∆K curves be determined and, if possible, a valid mathematical representation determined. The present paper demonstrates that for AM Ti-6Al-4V, AM 316L stainless steel, and AM AerMet 100 steel, the da/dN versus ∆K curves can be represented reasonably well by the Hartman-Schijve variant of the NASGRO crack growth equation. It is also shown that the variability in the various AM da/dN versus ∆K curves is captured reasonably well by using the curve determined for conventionally manufactured materials and allowing for changes in the threshold and the cyclic fracture toughness terms.

Original languageEnglish
Article number118
Number of pages19
JournalAerospace
Volume5
Issue number4
DOIs
Publication statusPublished - Dec 2018

Keywords

  • 316L stainless steel
  • Additive manufacturing
  • AerMet100 steel
  • Crack growth
  • NASGRO
  • Ti-6Al-4V

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