Shear Mode Stress Intensity Factors for Serrated Crack Fronts

Abstract:

The paper is related to experiments on near-threshold fatigue cracks under shear modes II, III and II+III in bcc metals. Cylindrical bars with circumferential cracked notch were loaded by shear force. In-plane precracks with microtortuous geometry were created by compressive cyclic loading in mode I to measure the effective values of the remote crack driving force. Fatigue cracks in bcc metals loaded under remote shear modes II, III and II+III always grew by creation of local tongues loaded in mode II and their coalescence. Therefore, serrated precrack fronts of a linear roughness identical to those of the real fronts were modeled and the related local stress intensity factors k₂ were calculated. Since such FEM calculation for various values of roughness were time consuming, a further task was to identify a lowest number of isolated teeth that produces k₂ components identical with those created by the continuously serrated crack front. The results reported in this article reveal that this condition is fulfilled by only two isolated teeth.

• Periodical: Key Engineering Materials (Volume 754)
• Pages: 214-217
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.754.214
• Online since: September 2017
• Authors: Stanislav Žák*, Jana Horníková, Pavel Šandera
• Keywords: Fatigue Crack Growth, Local Mode II, Serrated Crack Front, Shear Modes, Stress Intensity Factor

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