Introduction to the damage tolerance behaviour of railway rails – a review

Abstract

Despite substantial advantages in material development and in periodic non-destructive inspection together with periodic grinding and other measures in order to guarantee safe service, fatigue crack propagation and fracture is still in great demand as emphasised by the present special issue. Rails, as the heart of the railway system, are subjected to very high service loads and harsh environmental conditions. Since any potential rail breakage includes the risk of catastrophic derailment of vehicles, it is of paramount interest to avoid such a scenario. The aim of the present paper is to introduce the most important questions regarding crack propagation and fracture of rails. These include the loading conditions: contact forces from the wheel and thermal stresses due to restrained elongation of continuously welded rails together with residual stresses from manufacturing and welding in the field, which is discussed in Section 2. Section 3 provides an overview of crack-type rail defects and potential failure scenarios. Finally the stages of crack propagation from initiation up to final breakage are discussed.

Monitoring of strain of in-service railway switch rails through field experimentation

“…The variation in age of the S&C units instrumented was to give a representation of the (a) (b) Figure 6: The layout of strain gauges in the sleeper centre at (a) the neutral axis and (b) the names of the directions of the gauges, image from [18] development of strain over a longer duration. The cumulative tonnage allowed monitoring of the change in strain due to the total vehicles that had traversed the units.…”

“…The disadvantages include the installation on the NA is highly complicated, with the distance 82.26mm from the base [17]. The influence of the bending strain increases as the gauge moves further from the NA, but has been determined through Finite Element Modelling [18] not to be a significant factor in the error levels, within vertical installation tolerances.…”

“…th order lowpass Butterworth filter was applied to the outputted data at 100Hz, as it was found that above that frequency was insignificant through an FFT analysis of the strain data [18]. 50Hz was also removed through a passband filter due to the electromagnetic current (EMC), generating large amounts of noise.…”

Caracterização Microestrutural E Estudo Cinético De Transformação De Fases Em Dois Aços Standard E Premium De Aplicação Ferroviária

“…Para que o transporte ferroviário seja eficiente, é importante, entre outras coisas, garantir a integridade das ferrovias. Falhas catastróficas em trilhos, durante a passagem de composições, podem levar a descarrilhamentos, culminando em acidentes com perdas de vidas humanas e de bens materiais [2]. Avanços têm sido feitos na prevenção de falhas em trilhos por meio do aprofundamento do conhecimento dos mecanismos de fadiga, fenômeno este responsável pela causa da maioria das fraturas neste componente.…”

Background of recent developments of passenger railways in China, the UK and other European countries

“…In the early days of the privatisation of the railways in the UK, issues involving rolling contact fatigue of rails caused a significant accident which led to considerable efforts to rediscover issues originally well understood by British Rail Research. The first author was involved in investigating technical aspects of the accident in question: and some of the advances in understanding were discussed in a review (Zerbst, 2009).…”