PARAMETRIC STUDY ON RAILWAY FASTENING SYSTEM RESPONSE SUBJECTED TO DIFFERENT AXLE LOAD

There are several factors causing fastening systems to deteriorate faster than the designed life. The high repetitive loads from a moving train being one of the main factors, track irregularities, design and installation defects of track components, non-uniform rail support stiffness, unevenness in the rail seat deterioration are some of the factors causing fastenings systems to deteriorate faster than the theoretical design life span. The unevenness and the non-unifrom support structure induce higher dynamic forces into the track system leading to early failure of fastening system. The dynamic forces from the wheel-rail contact transfers to the track subgrade through the fastening system. The fastening acts as a damping to the track systems but itself experiences high magnitude undamped dynamic forces. The mechanical properties of the fastening system are the most important characteristics that directly determine the long-performance of this component. A finite element analysis was carried out to analyse the influence of mechanical properties and geometries of the fastening system on its deterioration. The analysis is done to determine the response of fastening system under different loading scenario by changing the mechanical properties. The parameters include: density, young’s modulus, yield strength and ultimate strength. A finite element model of a track system built is composed of standard rail(UIC60), railpad, abrasion plate, rail clip, bolt, insulator and half sleeper, all modeled as solid elements. The model is developed and analysed using finite element package ANSYS software. The result shows that the mechanical properties and thickness has a great effect on the fastening system components deterioration. It has shown that the density have a little effect among the parameters and on the other hand, the young’s modulus has seen to have a great effect among the parameters. Finally, the properties of a conceptual rail-fastening system for heavy rail have been identified. The results presented in this study add more knowledge on mechanistic design theory for fastening systems.