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PROCEEDINGS OF THE FIRST INTERNATIONAL CONFERENCE ON RAILWAY TECHNOLOGY: RESEARCH, DEVELOPMENT AND MAINTENANCE
Edited by: J. Pombo
Middle-Frequency Wheel-Rail Contact Forces of High Speed Trains and the Validation of a Model with Field Measurements
1The School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, P.R. China
X.C. Jin, "Middle-Frequency Wheel-Rail Contact Forces of High Speed Trains and the Validation of a Model with Field Measurements", in J. Pombo, (Editor), "Proceedings of the First International Conference on Railway Technology: Research, Development and Maintenance", Civil-Comp Press, Stirlingshire, UK, Paper 73, 2012. doi:10.4203/ccp.98.73
Keywords: high-speed train, instrumented wheelset, mid-frequency, wheel-rail contact force, track.
An important aspect of the development of railway transportation is the shortening of travel times. In China, a high speed passenger trains, being able to reach an operating speed of 350 km/h or higher, is being developed. The dynamic contribution to the wheel-rail contact force generally increases with increasing vehicle speed. In severe cases, the relative wheel-rail displacement excitation generated by the broad-band roughness and discrete irregularities present on the running surfaces of wheels and rails may lead to excessive contact forces. Often, these forces include dynamic components of significant magnitudes at mid- frequencies and high-frequencies. Such forces exacerbate deterioration of the wheelset and track components and lead to increased maintenance costs .
This paper focuses on the measurements of dynamic vehicle-track interaction and on further modeling development at mid-frequencies, from about 0 Hz to 500 Hz, for high-speed vehicles. In-field measurements have been performed to study the wheel-rail contact forces on the Chinese high-speed train in lines between Beijing and Tianjin. The forces have been measured by use of instrumented wheelsets, and a new technology has been introduced to include the mid-frequency content of the contact forces. Measurement methods are based on strain gauge bridges that have been calibrated with respect to static loads. Spectral analyses of contact forces have been subject to special investigations to obtain a better understanding of the mechanisms behind the high contact forces. It is found that wheel eigenmodes will influence the magnitudes of the measured strains that are transformed into wheel-rail contact forces. Meantime, it is found that the wheelset eigenmode resonances excited in the frequency domain, corresponds to a radial eigenmode with two nodal diameters, and a symmetric and antisymetric umbrella eigenmodes of the wheel, exhibit a magnification of the lateral force signals. An effective replacement or compensation can be introduced by using the wheel axle lateral force signals.
A vehicle-track interaction model that takes into account the flexible wheelset and track structures at mid-frequencies is proposed and validated by use of the results from field measurements. Wheel rotation has been taken account, and trigonometric function, together with modal synthesis have been used to solve the interaction between wheel and rail. Input data on wheel roughness are taken from field measurements. Good agreement is observed between the calculated and measured contact forces in the frequency range below 500 Hz.
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