Experimental analysis of surface cracks in rails under rolling contact loading

The wheel–rail interface is fundamental for the comfort and the safety of the train. For this reason the wheel and the rail surface condition are checked with periodic non-destructive controls. The presence of a crack can be tolerated if we are able to predict its evolution by using fracture mechanics concepts. The problem is complicated by the fact that surface cracks propagate in mixed mode conditions. In this paper a photoelastic technique is presented to experimentally determine the stress intensity factors in a model of cracked rail under contact loads. The first results are critically discussed.