Modelling of track wear damage due to changes in friction conditions: A comparison between AC and DC electric drive locomotives

The locomotive traction motor electric dynamics and its impact on the rail and vehicle have not been investigated deeply in transient wheel-rail contact conditions. Such transient traction behaviour could be more significant to dynamic traction performance and track degradation (i.e. corrugation formation, fatigue, wear, etc.) than steady state behaviour. In order to study this, detailed numerical simulations are performed to investigate the locomotive multi-body dynamic response to a change in contact conditions with an AC and DC electrical traction motor respectively. In particular, creep response, locomotive vibration, and dynamic normal and tractional forces are determined using a developed full scale locomotive dynamics model. The model includes the detailed AC and DC motor dynamics. Further investigation has been undertaken to understand the wear caused during and after the change of friction conditions from dry to wet and wet to dry. The result shows the GT46Ace locomotive AC drive can achieve higher traction efficiency compared to the equivalent DC drive running under notch 8, especially in the wet condition. It is also demonstrated that the AC drive produces slightly lower wear on average than the DC drive after the transient. However, the transient dynamic oscillation of wear caused by the AC drive is significantly higher than the DC drive.