REALISTIC PREDICTION OF RAIL STRESSES

Abstract

In the recent times, railways have been able to regain its importance due to their efficiency, ceo-friendliness and economical means of transportation system in developing countries. Fast technological developments have led to increase in train speeds with higher axle loads and more frequent train usage. This has posed new challenges to the railway engineering. This thesis deals with the review of current practices adopted in railway track analysis and design. The aim of this work is to develop a more comprehensive methodology for more accurate computation of rail stresses. The complexity of rail structure has not been completely understood, there are still some grey areas concerning the accuracy and reliability of the available methods of stress computation especially in the Indian scenario. Axle loads and traffic has been increased that railway tracks have to bear for providing efficient operation under the given service conditions. Moreover, some c o ncepts/ factors like creep, rolling contact fatigue (RCF), wear and other dynamic factors have been investigated which are responsible for overall reliability of railway track system and are needed to be introduced in the methodology to give the realistic prediction of rail stresses. The current rail stress calculations being used presently are reviewed thoroughly and discussed to obviate the influence of any approximations. The work presented in this project describes the wheel-rail creep force characteristics, which is based on Kalker's linear theory for contact mechanics especially in curving, in order to optimise the contact stress formulation. Furthermore, the concept of rolling contact fatigue, wear factor, contact mechanics and other dynamic considerations have also been reviewed to be suitably incorporated in the stress calculation methodology. The results presented in the paper are - expected to be useful to the designers