Investigation of Rail Bolt Hole Cracks

This document is a collection of two reports on the rail bolt hole 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 hole 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 hole 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 hole cracking: initiation, corner crack propagation, and through crack propagation up to and into the rail head. The initiation 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 hole surface. Dynamic load effects are considered and the most common occurrence of a bolt hole crack propagating away from the rail and toward the head is explained. Data are reviewed to show that fretting from the bolt or corrosion is probably necessary to initiate fatigue cracking. Estimates of the number of cycles required to propagate a corner crack to a through crack are given, including the effects of wheel eccentricity and lateral load. Several aspects of through crack propagation were considered. The stress intensity of a crack emanating from the first bolt hole due to bolt bearing is calculated for three crack lengths. Estimates of the stress intensity factors are also provided for various straight and kinked crack geometries in the rail head and along the head-web fillet. In addition, finite element analysis was performed to calculate the shear stresses distribution in a rail cross section (2D) and the stress intensity for a bolt hole crack that has entered the rail head (3D). The appendices to Part II describe the fracture appearance of three bolt hole cracks removed from service and a fixture design that could be used to break open bolt hole cracks.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 185p

Subject/Index Terms

Filing Info

  • Accession Number: 01665777
  • Record Type: Publication
  • Report/Paper Numbers: Report No. 89672
  • Contract Numbers: DTRS-57-83-C-0078
  • Files: TRIS, ATRI, USDOT
  • Created Date: Feb 12 2018 12:13PM