Evolution of rail rolling contact fatigue on heavy-haul curves and treatment optimization
To reveal the failure mechanism of heavy haul rails on sharp curves by rolling contact fatigue (RCF) and optimize the existing grinding strategies,field and laboratory tests and numerical simulations were conducted in consideration of different radii and gross traffic tonnages to investigate the evolution of the RCF on U75V HT rail installed on the heavy haul curves with different radii. It is found that the evolution of rail RCF with service time can be roughly divided into two stages:crack initiation and rapid propagation,and crack-wear symbiosis. After entering the crack-wear symbiosis stage,rail profiles deteriorate significantly on R600 m and R800 m curves,resulting in worsened wheel-rail match and severe spalling on the rail contact surfaces and threatening the running safety. The root cause is that the wheel-rail contact point moves to the rail shoulder once the rail is worn to a certain extent. For monitored curves with larger radii,no severe profile deterioration by wear was observed due to low wear rates,and no severe spalling was present. Failure analysis of replaced rails were performed in the laboratory. It is found that the maximum depth measured by the eddy current crack detector considerably different from the actual ones,the measured depth is generally larger,and the difference increases with the crack depth. To further extend the service life of heavy haul rails on R600 m and R800 m curves,it is recommended to increase the grinding frequency (especially within the first six months in service) to remove/control the cracks,for which the standard profile is preferred. For rails on curves with larger radii,the current grinding strategy seems to be sufficient.
heavy haul railwayrails on curvesrolling contact fatigueeddy current testingrail grinding
万方数据
维普
