Effect of Liquid on Rolling Contact Fatigue Cracks in Rail

Abstract:

A fluid-solid coupling numerical model considering the liquid and rolling contact fatigue （RCF） crack in rail based on the Coupled Euler-Lagrangian （CEL） method was established. The pressure distribution by the liquid on the crack internal surface under moving wheel-rail contact load was analyzed. The effect of the liquid with different viscosities on the RCF cracks with different lengths and propagation angles was researched. The conclusions show that the pressure by the high-viscosity liquid （HL） distributed on the entire length of the crack which was 4.8~5.9 times than that of the low-viscosity liquid （LL）. The closer to the crack tip， the greater the pressure generated by HL. And the maximum pressure on the crack tip reached about 690~751MPa in the example. With the wheel load passing the crack mouth， the HL still kept in the crack and the pressure by it on the crack surface lasted for a long time， about 80%~ 90% of a load cycle， with saddle-shaped pressure distribution on the crack surface. While the LL was extruded from the crack by the passing load which made the pressure mainly on the mouth and middle part of the crack for a short time， about 10%~30% of a load cycle， with peak-shaped pressure distribution on the crack surface. The larger the crack angle and the longer the crack length were， the more pressure on crack surface was and the easier the crack would propagate. When the crack angle was 30° and 40°， the hydraulic pressure by HL increased about 38.5%~63.8% and 1.1~1.2 times respectively compared to that of the crack angle with 20°. The maximum pressure by HL with 2.0 mm length was increased about 6.1%~8.3% than that of with 1.5 mm length.

Key words:rail;rolling contact fatigue;crack;liquid;fatigue damage