Short rolling contact fatigue and thermal cracks under frictional rolling – A comparison through simulations

• 3D coupled elastoplastic thermomechanical analyses of a cracked wheel (radial crack).
• Evaluation of crack face displacements for braking/driving cracked railway wheel under full and partial slip conditions.
• Thermal (radial) cracks found to be less severe than shallow inclined (RCF) cracks.
• Initial thermal loading tends to open thermal cracks, whereafter mechanical loading closes them.

The relative severity of radial (thermal) and inclined rolling contact fatigue surface cracks of equal depth in a railway wheel is investigated by three-dimensional elastoplastic finite element analyses of a cracked wheel sector subjected to contact loading. Response is quantified by relative displacements of nodes close to crack tip and at the crack mouth. Highly inclined cracks give the highest magnitudes of crack tip shear displacements, which is the dominant deformation mode. Braking conditions are found to open the crack mouth. Initially higher temperatures on thermal cracks cause increased crack tip deformation and opening of the crack, whereafter subsequent mechanical load cycles impose crack closure.