Rail thermal force calculations for jointed track

This is the link to the second article I wrote together with Levente Nogy – “Rail thermal force calculations for jointed track” – and published in the Permanent Way Institution Journal – Vol 135 Part 2 (April 2017). Article 2 Advertisements

Thermal forces and broken rails

Rail steel has a considerably higher carbon content (0.7-0.8%), and hence is more brittle than mild steel. A variety of stress concentrating defects in rails, combined with the alternating loads from the passage of traffic, can produce slowly propagating fatigue crack. When this crack attains a critical size it causes an almost instantaneous brittle fracture…

CWR stress transition zone

(prelude to a new PWI Journal article) A stress transition zone is any section of continuous welded rails (CWR) where the thermal force is variable, the longitudinal resistance (p) is active and rail movement occurs due to rail temperature variations. The most common (and well known) location of the stress transition zone is at the…

The rectangular coordinates of the Bloss transition

(Quickly but nostalgically written, remembering the good old days when Taylor was not yet known as the name of a beautiful singer but as the laborious math trick used to solve rather painful Mathematical Analysis problems …) The  deflection angle (θ) of the Bloss transition is: The rectangular equations (x and y) of the curve are…

A day in the life of a jointed track

ΔG = αLΔT°. Free expansion For a free thermal expansion jointed track the rails expand and contract freely and the track components do not provide any resistance to oppose this rail length variation. The joint gap varies linearly relative to the rail temperature. The figure below presents the joint gap variation for a jointed track formed…

When a 20 m rail is 20 m long?

Perhaps I’m splitting hairs here, but it is a fair question to ask: When a 20 m rail is 20 m long? Please, have your say and feel free to comment below, after voting! And this is not a trap question like “Which weighs more: 1 kg of steel rail or 1 kg of feathers?”. Later edit: By…

Significance of jointed track parameter variation

Joint resistance The normal rail joints are designed to allow the rail length variation due to temperature. To do this the joints have a well-defined maximum gap and a set of installation parameters to provide an optimum behaviour at temperature variation and a good maintenance regime. Any modern rail joint has a standard bolt tightening torque…