The most predominant failure mode of rails with bolt joints is a web crack initiating at the rail bolt hole. This failure mode is of a classical fatigue nature induced by web stress concentration around the bolt hole. This program was conducted to apply a metal-working process to the rail bolt hole to reduce the effect of such stress concentration and to demonstrate the effectiveness of the technique. Using a process known as cold hole expansion, common to the aircraft industry, where the bolt hole is expanded to the point of plastic deformation, a residual compressive stress of both radial and tangential components is formed around the bolt hole. The compressive stress developed effectively reduces the failure-initiating stress concentration at the bolt hole. The effectiveness of the cold-expansion process as applied to rail was demonstrated by comparison fatigue testing of both cold-expanded (CE) and non-cold-expanded (NCE) specimens. Laboratory tests indicated that life improvement for CE specimens was such that web or head failures would be the predominant failure mode, rather than CE bolt holes. The test results were statistically analyzed, indicating a factor of 10 or greater improvement in rail life due to reduction in bolt-hole failure could be anticipated. Experimental equipment was adapted to apply cold hole expansion to an 8.5 mile test section of track in commercial service. Evaluation of this field test is continuing.

  • Record URL:
  • Supplemental Notes:
    • See also RRIS 01 314087; Bulletin 8002. Also available in set of 3 reports PC E09, PB80-182173.
  • Corporate Authors:

    Boeing Commercial Airplane Company

    P.O. Box 3707
    Seattle, WA  United States  98124

    Transportation Systems Center

    55 Broadway, Kendall Square
    Cambridge, MA  United States  02142

    Federal Railroad Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Lindh, D V
    • Taylor, R Q
    • Rose, D M
  • Publication Date: 1980-2

Media Info

  • Media Type: Digital/other
  • Pagination: 76 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00314088
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: FRA/ORD-80/5.I Final Rpt., DOT-TSC-FRA-80-5-I
  • Contract Numbers: DOT-TSC-1048-1
  • Files: NTIS, TRIS, USDOT
  • Created Date: Aug 5 1980 12:00AM