Formulas for the critical length of mode II and III cracks emanating from circumferential U–notches

WoS Article

en

The crack emanating from the notch reaches its critical length when the notch ceases to have effect on the crack tip stress field. In this paper a semi–empirical approach to the critical length previously proposed for mode I cracks is extended to shear–mode cracks using finite element calculations. The existing formula for the critical crack length aIc of mode I cracks emanating from circumferential U–notches in round specimens is verified also for its invariance to the specimen thickness variation and its uncertainty is quantified to be less than 1 %. This uncertainty level is then employed to obtain statistically compatible formulae for critical crack lengths aIIc and aIIIc as functions of the notch depth, the notch-root radius and the notch depth normalized to specimen thickness. These formulae are useful for a correct determination of the pre-crack length free of the notch effect in fracture toughness experiments and for a proper evaluation of stress intensity factors in experimental investigations of fatigue crack propagation.

Critical crack length; Shear modes; Stress intensity factors; U–notch

2024-02-11

Elsevier

0013-7944

Engineering fracture mechanics

298

1

109955-1–109955-15

15