Technical Reports

Investigation of Rail Bolt Hole Cracks

  • 01
  • Oct
  • 1987
AUTHOR: R.A. Mayville, P.D. Hilton, D.C. Peirce
SUBJECT: Evaluation
KEYWORDS: Fretting, Rail, Rail End, Fatigue, Crack Initiation, Crack Growth, Corner Cracks, Bolt Holes, Stress Intensity Factor
ABSTRACT: This document is a collection of two reports on the rail bolt hold crack. part I describes the development of a model based on beam-on-elastic foundation analysis to calculate the shear force acting at a given bolt hold location. The model includes the effects of wheel and joint bar forces, joint efficiency factor, and dynamic wheel load amplification. Also described are experiments to derive the stress intensity - bolt hold crack length relationship for rail end loading representative of the joint. The stress intensity was found to be independent of crack length for the range studied: 0.5-3 in. The model and experimental results are used to predict crack growth rates for severe traffic conditions. Part II describes analyses of three stages of bolt cracking: initiation, corner crack propagation, and through crack propagation up to and into the rail head. The initation analysis makes use of the force model of the first report and results in the literature to calculate the mean and alternating stresses at the bolt hold surface. Dynamic load effects are considered and the most common occurrence of a bolt hole crack propagating away from the rail end toward the head is explained. Data are reviewed to show that fretting from the bolt or corrosion is probably necessary to initiate fatigue cracking.