Wheel-rail Interactions in High Speed Railway Networks during Rapid Train Transit

Abstract

Implementation of high speed railway networks in India requires a thorough investigation of the contact pressure and frictional stresses induced in wheel-rail interfaces during rapid train transit. In this study, 3-D numerical moving load simulations of wheel-rail interactions in broad gauge railway networks in India were performed for fast and heavy train operations, and the trends in variation of contact pressure and frictional stresses with increase in speed of the train were quantified. Simulations were performed in ANSYS, with a hybrid model incorporating a flexible wheel-set running over a couple of rigid rails, which aided in the estimation of frictional stresses at the interface of wheel-rail contact during train run, while maintaining a reduced number of elements associated with lengthy railway track sections. Analyses were done for train operations ranging from maximum speeds of 160 to 200 km/h and an axle load of 32.5 tonnes, as recommended by Indian Railways for operation of freight carriers in the existing broad gauge tracks. It was noted that with increase in speeds of trains, there was a reduction in the area of wheel-rail contact. The elliptical Hertzian contact patch of the static train wheels were found to transform into a more rounded patch during rapid train transit, causing concentration of stresses at the centre and effectively increasing the maximum stresses at the points of contact. Contact pressure and frictional stresses were found to increase quadratically, with an increase in the speed of the train. It was ascertained that the rate of wheel and rail wear during high speed train operations would be significant, and that high speed networks would require new wheel and rail sections, and the adoption of materials with very high frictional wear capacity.