Modelling thermal effects in ratcheting-led wear and rolling contact fatigue

Railway rails accumulate severe plastic deformation at the surface as a result of loading by passing wheels. This process of plastic strain accumulation is plastic ratcheting. Ratcheting failure occurs when material accumulates a critical strain and failed material produces wear debris and rolling contact fatigue cracks. A computer model of strain accumulation, ratcheting failure and wear has been developed which can be used to simulate and predict wear and crack initiation in rails. The current work incorporates thermal stress and material softening due to frictional heating in the contact area into the computer simulation. The effects of friction coefficient and slip/roll ratio on the wear rate and rolling contact fatigue are investigated, and frictional heating effects have been found to increase the rate of damage accumulation by ratcheting, leading to increased wear and tendency for rolling contact fatigue.