Saeed Hossein Nia

Wheel damage on the Swedish iron ore line investigated via multibody simulation

The Swedish iron ore company LKAB uses freight wagons with three-piece bogies to transport iron ore from its mines in Kiruna and Malmberget to the ports at Luleå and Narvik. A simulation model of the freight wagon is built using the multibody simulation code GENSYS. The objective is to investigate possible sources of rolling contact fatigue (RCF) of the wheels given the high level of observed damage. A parameter study is performed on the effects of vertical track stiffness and viscous damping that occur as a result of seasonal variations of the track condition. Another parameter study is carried out on the influence of the wheel/rail friction coefficient as in winter time the climate is very dry along most parts of the Malmbanan line. The impact of track gauge, track quality and cant deficiency on RCF is also studied. Comparing the calculated and observed RCF locations on wheels, attempts are made to find a relation between wear number and RCF damage. To detect the surface-initiated fatigue a so-called shakedown map is used. It is shown that RCF occurs on the tread of the inner wheels while negotiating curves with below an approximately 450 m radius. It is also shown that cant deficiency can be helpful for the vehicles to negotiate curves and to reduce the risk of RCF, however, on the other hand it may increase the track forces and in severe cases result in flange climbing. Lateral track irregularities and a large track gauge result in small contact areas and can lead to a higher risk of RCF. In cold dry climate conditions, as the water content in air drops significantly, the wheel/rail friction coefficient increases and when the material in the wheel begins to behave in a brittle manner, the risk of RCF is significantly increased, especially when the wear rate is not high enough to remove the initiated cracks.