Ranking of endpost materials of insulated rail joints for cyclic wheel loadings

Insulated rail joints (IRJs) are important for railway operations and controls. Endposts are used in IRJs to create electrical signal blocks to locate trains and broken rails. They are inserted in the gap between two adjacent rail ends. The popular endpost materials are fibreglass (fb), polytetrafluoroethylene (ptfe), nylon (ny), etc. The ranking of these endpost materials has been carried out in this study. Because of rail end gaps at IRJs, the bending rigidity is less, and a stress singularity occurs with associated damage to endpost and railhead material. A plastic flow occurs of the rail top material and reduces the effective thickness of the endpost materials and can disrupt the electrical signalling circuits. Therefore, a good endpost material is needed to retard the lipping process. Indirectly, the endpost materials are controlling the railhead sub-surface damage that influences the crack initiation. Hence the behaviour of endpost materials can be researched, focusing not only on the lipping problems but also on sub-surface damage analysis with a view to determining a hypothesis linking endpost elastic material properties and the degree of railhead damage and lipping. To establish the hypothesis, a 3D finite element analysis (FEA) is carried out on IRJs considering fibreglass endpost materials and loading conditions using a cyclic vertical wheel load up to a total of 2000 cycles.