Failure analysis: rail contact

Repeated rolling or sliding contacts stresses the material cyclically. Dependant on the contact stresses the material responds in one of the following four ways,

1. Perfectly elastic behavior if the contact pressure does not exceed the elastic limit, i.e. for a line contact pmax/τc= 0.31 or expressed in the load intensity τc/pmax=1/0.31.
2. Elastic shakedown behavior, in which plastic deformation takes place during running in, while due to residual stresses or strain hardening the steady state is perfectly elastic.
3. Plastic shakedown behavior, in which the steady state is a closed elastic plastic loop, with no net accumulation of plastic deformation.
4. Ratcheting behavior, in which the steady state is an open elastic plastic loop, the material accumulates a net strain during each cycle.
   

For full description of failure analysis and remedy see reference .