ANALYSES OF TRANSIENT WHEEL-RAIL ROLLING CONTACT BEHAVIOR DURING CURVING

A 3-D transient wheelset-rail rolling contract model has been developed for a metro in China. The explicit finite element method was used to model the transient rolling contact behavior of a free wheelset passing over a curve of R300 m in the time domain. Focus was placed on the resulting contact forces, stresses, relative slip, stick-slip distributions and friction work applied by the wheel-rail contact. Two cases were considered including smooth rails (without geometry irregularity) and one-side short pitch corrugation. With respect to the previous models of half-wheelset or full-wheelset on tangent tracks, super-elevation, curved rails, lateral shift and roll-over of wheelset, etc. were all taken into account. Results over smooth rails at 50 km/h (the equilibrium speed is 50.42 km/h) have shown that the wear on the outer rail concentrates near the gauge angle and is approximately 3.1 times larger than that on the inner rail; the contact forces, stresses and friction work increase significantly as the lateral shift increases. These results are consistent with on-site observations and provide preliminary validation of the model. The short pitch corrugation on one rail can not only lead to uneven wear on the corrugated rail, but also slight uneven wear on the smooth side. The amplitudes of the frictional work fluctuations on non-corrugated rail resulting from corrugation on the inner is about 1.9 times that from corrugation on the outer one, suggesting that corrugation exiting on the inner rail can trigger the occurrence of corrugation on the smooth side more efficiently. In addition, whether the corrugation is on the inner or outer rail, the amplitude of the frictional work reaches its minimum on both sides at a speed between 40 km/h and 50 km/h (being slightly lower than the equilibrium speed), i.e. the growth rate of corrugation is minimum.