Volume 6, Issue 3 (May 1978)
The Effect of Interference on the Dimpled, Loaded-Hole Fatigue Strength of 2024-T3 Alclad® Aluminum Alloy
The effect of interference fit on the fatigue strength of loaded holes is well known. Recently a new technique has been developed for increasing this strength in thin sheet material. The technique consists of dimpling the material centering about the region where the hole is to be made and thus introducing tensile plastic strain. The dimple is then flattened and the hole drilled, leaving the region around the hole under residual compressive stress. Experiments were carried out to obtain the combined effect of interference and dimpling in loaded-hole fatigue applications. In zero-totension fatigue tests on nominally 1.60-mm (0.063-in.) thick 2024-T3 Alclad® aluminum alloy specimens, combined optimum tapered-pin interference and dimpling gave a fatigue strength improvement factor of 4.0 while the dimpling technique increased the fatigue strength by a factor of 2.85 at 106 cycles to failure.