CORRUGATION - Wheel rail corrugation in urban transport
Overview
Background & policy context:
“CORRUGATION” was an EU funded research project which aimed at development of solutions for the expensive and persistent corrugation problem on metro and tram networks.
Corrugation is an annoying and costly phenomenon that reduces the lifetime of both wheels and rails, causes an irritating emitted rolling noise and leads to safety concerns.Up till now, No real cure exists and the only available solution is grinding the rails, which is a costly and recurring process.
Objectives:
The aim of the project was to design and validate efficient and cost effective solutions to reduce or eliminate the corrugation problem. The corrugation phenomena was considered for vehicles with low axle load, running at low speed in curves with small radius, typical urban transport.
Further, the goals were to increase safety, reduce noise and life cycle costs and optimise maintenance costs. These goals have been met.
Methodology:
Corrugation measurement equipment:
Dedicated measurement equipment and measurement methods have been selected or specifically developed for the measurement of corrugation and all relevant parameters that influence corrugation.A new manual corrugation measurement device was developed alongside a new laser based measurement device.Measurements have been carried out on the test sections to verify and compare the performance and accuracy of the selected devices and methods.These measurements were further used in the project as reference data and compared with measurement data after modification of the track and wheelset parameters that influence corrugation.
Numerical modelling of macroscopic wheel/rail forces:
Two different multi-body dynamics models, portraying the passage of a railway vehicle on a track, have been developed and tested separately.A common test case was defined and both models have been validated by comparing the predictions of the models with the results of measurements on a reference track section.
A lumped parameter model has also been developed and progressively tuned and updated in order to fit the various measured data.
Finally, a finite element model ballasted track on wooden sleepers was been developed.The parameters of the model were been updated based on the results of experimental measurements on site and in the laboratory.A sensitivity analysis has been carried out to evaluate the influence of rail pad and undersleeper pad stiffness and modal damping on the rail transfer functions.
All the numerical models converged to same findings:
It is not the P2 resonance (i.e. first wheel-rail vertical bending) which is related with corrugation wavelengths, but especially vertical anti-resonances as well as rail lateral and wheelset lateral resonances (in second order).This is a major finding of this project.
Embedded rail can prevent the formation of corrugation, provided that a sufficient level of rail damping is inserted.
Wheelset test rig for corrugation wear simulation:
An existing full scale wheel/rail interface test rig used for research and fatigue testing has been adapted to simulate the effect of stick-slip at the wheel/rail interface.After 200 km, corrugation has appeared on the rails, showing the different steps responsible for corrugation in real conditions.It is the first time that rail corrugation initiation and growth have been replicated on a test bench.This test rig was further u
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