Fatigue thresholds of precracked specimens predicted by modified strip-yield model for plasticity-induced crack closure

• Published in: Theoretical and applied fracture mechanics Vol. 122; p. 103635
• Main Authors: Tanaka, K., Akiniwa, Y.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-12-2022
• Subjects: Crack closure; Crack growth threshold; Fatigue limit; Material defects; Short crack propagation; Strip-yield model; Short crack propagation; Crack growth threshold; Material defects; Fatigue limit; Strip-yield model; Crack closure
• ISSN: 0167-8442; 1872-7638
• DOI: 10.1016/j.tafmec.2022.103635

•The effects of precrack lengths and material yield stress on crack closure development are examined.•A new master curve equation is proposed for the cyclic R-curve.•The fatigue thresholds of materials with defects are successfully derived.
A strip-yield model modified to leave plastically deformed stretch in the wake of the advancing crack tip is applied to simulate the development of plasticity-induced crack closure with crack extension from precracks with various lengths under the stress ratio R = 0. The effects of precrack length and yield stress on fatigue thresholds were systematically examined. Because of a sharp increase of crack opening stress with crack extension, the effective stress intensity range ΔKeff drops initially and then turns to increase. Assuming the threshold value of ΔKeff for steels, a master curve equation is proposed for the cyclic R-curve. The effects of precrcrack length and material yield stress on fatigue thresholds are successfully derived.