Progress in understanding of intrinsic resistance to shear-mode fatigue crack growth in metallic materials

Tomáš Vojtek, Jaroslav Pokluda, Anton Hohenwarter, Reinhard Pippan

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13 Citations (Scopus)


Recently made experiments allowed measurement of effective data (free of crack tip shielding) and enabled a better understanding of intrinsic behaviour of shear-mode cracks. Influence of crystal structure and microstructure was distinguished. Experimental results for niobium showed that growth micromechanisms and effective thresholds (ΔKIIeff,th ≈ 1.0 MPa m1/2, ΔKIIIeff,th ≈ 1.4 MPa m1/2) of modes II and III cracks were different, which was also observed in other metals. Validity of the simple formula for mode II effective threshold for single-phase metals based on the dislocation emission model was confirmed. The cracks propagated in a coplanar manner along the maximum shear plane, which is a characteristic behaviour for bcc metals. Model of propagation of remote mode III loaded cracks by local mode II advances was confirmed.

Original languageEnglish
Pages (from-to)36-42
Number of pages7
JournalInternational Journal of Fatigue
Publication statusPublished - 4 Oct 2015


  • 3D fractography
  • Effective threshold
  • Micromechanisms
  • Modes II and III cracks
  • Niobium

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