Study of cyclic crack-tip opening displacement of microstructurally small fatigue crack using digital image correlation

Ilari Tillikainen, Pasquale Gallo*, Pauli Lehto, Heikki Remes

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

1 Citation (Scopus)
23 Downloads (Pure)

Abstract

The current work investigates the relationship between the crack growth rate (CGR) and the cyclic crack-tip opening displacement (ΔCTOD) of microstructurally small fatigue cracks by using high-resolution digital image correlation (DIC). Load-controlled fatigue tests were conducted on small-scale specimens of 18%Cr body-centered cubic ferritic stainless steel. Microstructurally small fatigue crack growth was analyzed based on accurate high sample-rate measurements, starting from a sub-grain crack length up to seven times the volume-weighted grain size dv = 224 μm. Under these experimental conditions, the high-resolution analyses reveal that variation from the otherwise linear relationship between CGR and ΔCTOD on double logarithmic scale is due to the crack-tip bypassing an inhomogeneous shear strain localization zone. In this zone, ΔCTOD is not able to characterize the behavior of microstructurally small fatigue cracks. Outside the shear strain localization zone, ΔCTOD still is a valid crack driving force parameter.

Original languageEnglish
Pages (from-to)4103-4118
Number of pages16
JournalFatigue and Fracture of Engineering Materials and Structures
Volume46
Issue number11
Early online date10 Aug 2023
DOIs
Publication statusPublished - Nov 2023
MoE publication typeA1 Journal article-refereed

Keywords

  • crack growth rate
  • crack tip opening displacement
  • ferritic stainless steel
  • small crack
  • strain localization

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