FEA to assess plastic deformation of railhead material damage of insulated rail joints with fibreglass and nylon endposts

Railhead material becomes severely stressed due to localised cyclical wheel/rail contact loadings. The stress situation is more critical in the vicinity of the endpost of an insulated rail joint (IRJ). As the contact point moves towards the endpost, the wheel loading peak pressure increases sharply, not following the well-known Hertzian Contact Theory (HCT). With a view to finding a more suitable design of IRJs to bear the pressure singularity and reduce impact force and damage of railhead material, nylon 66 (ny) along with fibre-glass (fg) endposts in IRJs have been considered. This paper presents a 3D finite element analysis targeting damage and stress distributions in the railhead material near the endposts. The following design parameters are considered: 5mm endpost thickness in a 6-bolt IRJ centrally suspended between two sleepers. A non-linear isotropic and kinematic material hardening model is used to represent elastic-plastic behaviour. 2000 loading cycles in the form of wheel pressure using the amplitude function in ABAQUS are applied for this analysis. Critical strain and stress components are determined to quantify railhead damage. The effects of both fg and ny endpost material on the mechanical behaviour of IRJs are analysed to find the best design. In this regard, progressive damage parameter and von-Mises stresses are considered to determine plastic deformation and material degradation of the railhead material.