Growth Life of Surface Cracks in the Rail Web

PDFTech ReportDOT/FRA/ORD-89/DOT-TSC-FRA-89-01DTRS-57-85-C-00093CrackingFracture mechanicsMathematical modelsRail (Railroads)United StatesUnited States. Federal Railroad AdministrationJeong, David Y.John A. Volpe National Transportation Systems Center, (U.S.)Lehigh UniversityUnited States. Federal Railroad AdministrationAGR-INFRASTRUCTURE-RailroadsNTL-RAIL TRANSPORTATION-RAIL TRANSPORTATIONNTL-RAIL TRANSPORTATION-Rail SafetyNTL-SAFETY AND SECURITY-Vehicle DesignNTL-SAFETY AND SECURITY-Rail SafetyNTL-SAFETY AND SECURITY-SAFETY AND SECURITYVolpe National Transportation Systems Center, Technical Reference CenterThe results of a theoretical study of the propagation behavior of surface cracks in the web of railroad rails are presented. Two fracture mechanics models are presented: (1) a conventional LEFM model of an elliptical surface crack of constant aspect ratio growing through the web thickness; and (2) a generalized surface crack model based on Sih's strain energy diversity approach. The conventional model predicts that the crack will propagate only at extremely slow rates, even under conditions of tensile vertical residual stress created by roller straightening. The strain energy diversity model predicts a slow propagation principally along the web (i.e., the crack aspect ratio increases) without residual stress