Local Residual Stress Near Fatigue Crack Tip

摘要

The distribution of residual stress near the tip of a fatigue crack propagating under constant amplitude stress cycling accompanied by several cycles of overloads was measured using an X-ray microbeam diffraction technique. The residual stress measured in the close vicinity of the crack tip was compressive and gradually changed to tensile at a certain distance from the crack tip. The compressive residual stress became higher as the number of overload cycles increased. The high compressive residual stress may be responsible for a large amount of growth retardation of a fatigue crack due to increasing numbers of overload cycles. A theoretical method to predict the growth rate of a fatigue crack from information on the local residual distribution near the tips of fatigue cracks is presented.