Out-of-round railway wheels - wheel-rail contact forces and track response numerical simulations

The influence of different types of railway wheel out-of-roundness (OOR) on the vertical dynamic wheel-rail contact force and track response is investigated through extensive field tests and numerical simulations. The response from a freight train, provided with a number of different types of severe wheel tread damage, is studied. Two different axle loads are used in combination with different train speeds in the range 30-100 km/h. The wheel defects are wheelflats, local spalls due to rolling contact fatigue cracking, long local defects and polygonal wheels (periodic OOR). The vertical wheel-rail contact force was measured using a strain gauge based wheel impact load detector. Strain gauges and accelerometers were positioned on rails and sleepers to measure the track response. Most of the magnitudes of measured impact forces were found to be lower than the current impact load limit that is used in Sweden to determine when a defective wheel should be removed for repair. Only the long local defect caused larger force magnitudes than the wheel removal criterion. Measured responses are used to calibrate and validate numerical models for simulation of train-track interaction. Results from one linear and one state-dependent track model are compared.