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

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 Delta Keff drops initially and then turns to increase. Assuming the threshold value of Delta Keff 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.

Automated summary

This study modifies a strip-yield model to simulate the plasticity-induced crack closure during crack extension from precracks with various lengths. The effects of precrack length and yield stress on fatigue thresholds are systematically examined.