The fracture toughness KIC of the m

The fracture toughness KIC of the material could not be determined because the size of the specimens that could be extracted from the rail would not yield valid results. The KQ value was determined and was found to be approximately 27 MN∙m-3/2 (±2 MN∙m-3/2) at all specimen positions in the rail.Constant load amplitude four point bending fatigue tests were carried out on a section of a rail to assess the accuracy of the numerical and analytical solutions. A UIC60 rail section, the most common rail profile in European railways, was used. The rail support span was 750mm and the loading point span 190mm. The maximum applied fatigue load was 582kN with a frequency of 1Hz and an R ratio of 0.3(R=Pmin/Pmax). The fatigue tests were alloed to continue until complete fracture of the rail took place.
Once a crack had initiated, the test was stopped and the crack heat tinted in order to determine the shape of the crack front just after initiation and how this changes as the crack front propagates to failure.