Predicting crack growth and risks of rail breaks due to wheel flat impacts in heavy haul operations

Abstract

The risk for rail breaks is investigated from mechanical and statistical points of view with particular focus on the influence of impact loads from flatted wheels. For a presumed rail head crack geometry and rail temperature, the stochastic relation between the crack position along the rail and the wheel flat impact position results in a risk of fracture. In addition to the analysis of the risk for final fracture, rail crack growth is also studied. In particular, the contribution of wheel flat impacts on crack growth rates is quantified. The study takes the form of a dynamic load analysis that evaluates rail bending moments due to wheel flat impact. Then, a fracture mechanics analysis is employed to establish stress intensity factors for rail head cracks under bending and temperature loading. These analyses are then combined to give risks of rail breaks and to quantify crack growth rates for varying operational conditions.