Avoiding knife-edge countersinks in GLARE through dimpling.

Traditional machine countersinking practices create a knife-edge condition in one or more of the outer aluminium layers in riveted GLARE joints. Press countersinking (dimpling) provides an alternative method of countersinking that prevents the formation of a knife-edge; however, its application and potential benefits to fatigue performance in GLARE are not known. This paper investigates the dimple-forming process and its application to GLARE, and the resulting benefits in fatigue crack-initiation life in unfilled rivet holes. Initial results showed that the limited formability of GLARE complicates the dimpling process, but that dimpling shows promise as a method for increasing the crack-initiation life of riveted GLARE joints. [ABSTRACT FROM AUTHOR]