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A modelling procedure was developed which is applicable to crack growth in notched components subjected to multiaxial fatigue for materials with different microstructures. An algorithm for crack growth, in a microstructure that was modelled as hexagons, was established as a competition between growth by crack linkages during the crack initiation and propagation stages and the propagation of a dominant crack as a single crack. Analytical results simulated by using the developed model were compared with experimental results from fatigue tests which had been conducted using notched specimens of pure copper, carbon steel and two kinds of titanium alloy. Cracking morphology, which was experimentally observed to depend on the microstructure and the loading mode, was well simulated using the present model. The fatigue failure life of a notched specimen was statistically estimated by a Monte Carlo procedure based on the model. The simulated life with a statistical scatter‐band almost coincided with the experimental data.

Abstract--Biaxial tension compression fatigue tests were conducted with cruciform shaped specimens in a closed-loop servo hydraulic testing machine. The effects of static and cyclic non-singular stresses acting parallel to the crack plane on the crack growth rate are discussed based on the experimental observations 0 1 crack opening behaviour and fractography. Those non-singular stresses did affect the growth rate significantly under certain conditions. The range of crack-tip opening displacement was found to be a better parameter in correlating the growth rate than the stress intensity range or its elfective range. The rate tended to increase with increasing non-singular stress which is correlated to the opening displacement range. This tendency was explained by the shift of fracture mechanisms to a more brittle type due to a higher elevation of hydrostatic stress near the crack tip for the case of a larger non-singular stress term.

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