Rail Track Failure Caused by Rolling Contact Fatigue Cracks
Railroad rails are subjected to damage from rolling contact fatigue, which leads to defects such as shell cracks. When shell cracks reach a critical length, they may branch downward and cause a more problematic defect called a detail fracture. If not repaired, detail fractures may lead to complete fracture of the rail and result in catastrophic derailments. This study investigates the propagation of shell cracks in heavy haul rails in order to identify factors that cause transition from a shell crack to a detail fracture. Two-dimensional finite-element simulations of crack propagation provide an understanding of how crack length, crack depth, and mixed-mode loadings cause downward branching of shell cracks. Some stress intensity factor results are inconclusive due to analysis limitations. However, this study demonstrates that crack-growth criteria that cause propagation in the direction of maximum mode-I loading, are inappropriate for the analysis of subsurface shell cracks. Previous research has concluded that the primary cause of growth of shell cracks is due to mode-II loading induced by wheel-rail contact friction. This work shows that a shear crack-growth criterion is necessary for the analysis of shell cracks.
School:
University of Texas Pan-American
Research Advisor:
Glaucio H. Paulino
Department of Research Advisor:
Civil and Environmental Engineering
Year of Publication:
2004