Comparison of fatigue crack retardation methods

The efficiency of several fatigue crack retarding methods are examined. Al-alloy flat specimens with a central ''key hole'' starter notch were tested in a closed-loop servo hydraulic test machine. After the cracks had propagated to a predefined value, the following crack retarding methods were undertaken: repair welding, welded metal reinforcements, adhesively bonded CFRP patches, single peak tensile overloads and fatigue crack arrest holes. Fatigue test programmes were performed with constant load amplitudes and spectrum tensile loads. The results show that expanded and filled crack arrest holes, and CFRP patches applied to both sides, are the best fatigue crack retarding methods with all load conditions. Copyright (C) 1996 Elsevier Science Ltd.