Plastic deformation of railhead material of insulated rail joints

Insulated rail joints (IRJs) are essential for railway operations and control. Endposts are used in IRJs to create electrical signal blocks to locate trains and broken rails. The endposts are inserted in the gap between two adjacent rail ends. Commonly used endpost materials include fibreglass (fb), polytetrafluoroethylene (ptfe), and nylon (ny). Plastic deformation occurs in railhead top material at IRJs, reducing the endpost material’s effective thickness (lipping), which can disrupt the electrical signalling circuits and increase vertical deformation (dipping). A good endpost material can retard the lipping and dipping processes associated with this plastic flow. Indirectly, the endpost materials influence the railhead sub-surface damage that influences the crack initiation in the railhead. Hence the mechanical behaviour of endpost materials can be researched focusing not only on the lipping and dipping problems, but also on railhead sub-surface damage analysis. Therefore, a coupled 3D finite element analysis (FEA) is carried out on an IRJ mainly considering all three commonly used endpost materials and vertical wheel loading conditions up to 2000 cycles. Because of cyclic wheel loadings on IRJs, lipping and dipping occur. For causing less sub-surface railhead material damage to retard the crack initiation, the most influential endpost material is fb.