Fatigue performance of production-quality aircraft fastener holes

A two part study was conducted on the effects of hole drilling on the fatigue life of aircraft rivet holes in 2024-T3 aircraft quality aluminum. The first part of the study determined the drilling parameters that had the greatest effect on hole quality. In this, the second part of the study, the fatigue lives resulting from these drilling parameters are compared. It was found that machining marks play a greater role than residual stress in the fatigue life of production-quality holes. Machine drilling greatly reduces machining marks, increasing fatigue life by almost a factor of three. Dull bits appear to increase residual stress, but also increase machining marks, resulting in an approximately equal overall fatigue life.