Sleeve Coldworking Fastener Holes. Volume I. Discussion and Summary

摘要

In this 21-month program, optimized process parameters for sleeve coldworking of fastener holes have been developed, and the effects of process and application parameters on structural performance have been defined for selected aluminum, titanium, and high-strength steel alloys. The sleeve coldworking process for fastener holes is a process that uses a tapered mandrel in conjunction with a disposable, prelubricated sleeve to compressively prestress a significant size zone around each hole which offsets the stress concentration of the hole itself. The sleeve method allows higher degrees of prestressing than possible with other methods and offers potential for significant improvements in fatigue performance. In addition, it does not require precision controls germane to other fatigue-rate hole preparation/fastener installation systems. This technical report covers the results of this 21-month program. In addition to definition of optimized methods and the effects of process and application variations upon structural performance, the results include performance and economics comparisons for the process with other fatigue-rate hole preparation/fastener systems. Volume II contains test data sheets and other supporting data. (Author)