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|Title: ||The steady state forces and moments on a railway wheelset including flange contact conditions.|
|Authors: ||Brickle, Barrie V.|
|Issue Date: ||1973|
|Publisher: ||© Barrie Vaughan Brickle|
|Abstract: ||Railway vehicles are fitted with coned wheels to provide
a measure of stability, but it can be shown that since the forces between
wheel and track are non-conservative, dynamic instability occurs at
a certain critical speed. Under these conditions the wheelsets sway from
side-to-side of the, track with the flanges of the wheels contacting the rails.
This can lead to derailment when the wheel climbs up the rail and
eventually jumps off.
The forces which exist between wheel and rail are due to the
phenomenon known as "creepage", and various theories exist which predict
these forces in the plane of the contact area. An investigation has been
carried out into these theories with the railway wheelset problem in view,
particularly the flange contact case.
It is possible, by assuming small displacements which avoid
flange contact, to carry out a linearised study of the lateral dynamics
of a wheelset, but the presence of the wheel flanges introduces a nonlinearity
into the problem.
A mathematical model of a wheelset and track has been defined
based on real wheels with a "worn" tyre profile and real track. Computer
programs have been written which calculate the contact points when the wheelset
is displaced laterally and yawed by various amounts, including flange
,contact conditions. Up to three contact points can exist between the wheelset,
and track. Forces in the contact areas have been calculated using the
various theories assuming the wheelset to be rolling along the track a ta
constant velocity in a displaced position. These forces have been
manipulated to give the total forces and, moments on the wheelset and are
presented for various vertical load distributions and for various angular
and lateral displacements of the wheelset from its central position.
Although theories exist which predict the forces for flange
type contact, i. e. very elongated contact ellipse with a large amount of spin
present, it became apparent during the course of the investigation that very
little experimental evidence was available for such conditions. As a result
a roller rig was built to provide this data, and measurements were made of·
the lateral force due to various amounts of lateral creep and spin on
elongated contact ellipses. Results from these tests have been compared
with the available theories and show reasonable agreement.|
|Description: ||A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.|
|Sponsor: ||British Rail|
|Appears in Collections:||PhD Theses (Aeronautical and Automotive Engineering) |
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