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Split mandrel versus split sleeve coldworking: Dual methods for extending the fatigue life of metal structuresIt is common practice to use split sleeve coldworking of fastener holes as a means of extending the fatigue life of metal structures. In search of lower manufacturing costs, the aerospace industry is examining the split mandrel (sleeveless) coldworking process as an alternative method of coldworking fastener holes in metal structures. The split mandrel process (SpM) significantly extends the fatigue life of metal structures through the introduction of a residual compressive stress in a manner that is very similar to the split sleeve system (SpSl). Since the split mandrel process is significantly less expensive than the split sleeve process and more adaptable to robotic automation, it will have a notable influence upon other new manufacture of metal structures which require coldworking a significant number of holes, provided the aerospace community recognizes that the resulting residual stress distributions and fatigue life improvement are the same for both processes. Considerable testing has validated the correctness of that conclusion. The findings presented in this paper represent the results of an extensive research and development program, comprising data collected from over 400 specimens fabricated from 2024-T3 and 7075-T651 aluminum alloys in varied configurations, which quantify the benefits (fatigue enhancement and cost savings) of automating a sleeveless coldworking system.
Document ID
19950013084
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Rodman, Geoffrey A. (West Coast Industries, Inc. Seattle, WA, United States)
Creager, Matthew (Structural Integrity Engineering Chatsworth, CA., United States)
Date Acquired
September 6, 2013
Publication Date
September 1, 1994
Publication Information
Publication: NASA. Langley Research Center, FAA(NASA International Symposium on Advanced Structural Integrity Methods for Airframe Durability and Damage Tolerance, Part 2
Subject Category
Structural Mechanics
Accession Number
95N19500
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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