Technical Reports

Stub Sill Tank Car Research Project Results of a 15,000 Mile Over the Road Test

  • 01
  • Sep
  • 1995
SUBJECT: Evaluation
KEYWORDS: Freight Equipment Environmental Sampling Test, Vertical Coupler Force, Stub Sill Tank Car
ABSTRACT: The Federal Railroad Administration (FRA) has been investigating incidents of fatigue cracking of the stub sill and at the attachment of the stub sill to the tank shell of stub sill type tank cars. Over 162,000 of these cars have been placed in service since 1950. The FRA has also issued Emergency Order #17, which asks the railroad industry to investigate further failures of stub sill tank cars and recommend preventative measures. The AAR TTC was tasked to investigate and define the forces imposed on the structure and validate the AAR'S Freight Equipment Environmental Sampling Test (FEEST). Data collected during the 1988 FEEST included vertical coupler force (VCF) levels, which were characterized by a high force level "hump" in the histogram. When used in a previous fatigue analysis project, the hump resulted in a severe reduction of the expected fatigue life of stub sill tank cars. Because of this, the validity of the FEEST data, contained in the AAR Manual of Standards and Recommended Practices, has been questioned.
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