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Laboratory, Japan

Doi H.,Vehicle Mechanics Laboratory | Miyamoto T.,Vehicle Mechanics Laboratory | Suzumura J.,Lubricating Materials Laboratory | Nakahashi J.,Vehicle Dynamics Laboratory | And 2 more authors.
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2012

A number of flange climb derailments have occurred in sharp curves or curves with turnouts within relatively short accumulated running distances subsequent to wheel turning. This indicates that a change in the condition of the turned wheel surface might be a factor inducing flange climbing. Through several experiments and numerical simulations, the authors investigated the relationship between the running safety of a vehicle and its wheel surface condition especially in terms of wheel/rail friction. Furthermore, lubrication just after wheel turning was proposed as a countermeasure to flange climb derailments and its effectiveness and persistence were evaluated. Source

Urakawa F.,Track Dynamics Laboratory | Abe K.,Niigata University | Takahashi H.,Niigata University
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2016

In order to evaluate the axial force of a continuous welded rail quantitatively in a simple manner, a method was developed to measure axial force based on the natural frequency. However, the accuracy of this method is insufficient because of certain variations in track condition. This study extracted factors which influence measurement accuracy and proposed an error correction method using track finite-element analysis for the purpose of improving the accuracy of this measuring method. Furthermore, measurements were taken of the natural frequency and axial force of a rail on a real track in order to validate the proposed method. © 2016, Ken-yusha Inc. All rights reserved. Source

Aikawa A.,Track Dynamics Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2015

This paper describes research into the dynamic responses measured on a commercial-line with ballasted track using sensing sleepers and sensing stones both of which were developed by the author, for the purpose of gaining new knowledge that will contribute to measures against track deterioration and effective track maintenance. The research further analyzed the measurement results in terms of the spectral characteristics of ballast behavior and the vertical natural vibration characteristics of ballast layers. The results of the spectral analysis show that the rigid-body vibration mode of sleepers is in a frequency range lower than 100 Hz and also reveal that the elastic vibration modes of ballast layers are in a frequency range as wide as 400-800 Hz. This series of analyses suggests the possibility that the dynamic load of a passing train is hard to damp, affected by its resonance. Furthermore, the author performed a full-scale drop-weight impact test and found from the test result that when the impact load works on a ballast layer, unloading causes abrupt release of stress, which led to decreased contact force between particles and a jumping behavior in the ballast layer. Source

Tsujie M.,Track Dynamics Laboratory | Akama M.,Vehicle and Bogie Parts Strength Laboratory | Namura A.,Track Dynamics Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) (Japan) | Year: 2011

Accurately analyzing the propagation of transverse cracking which causes rail failure is important to ensure train operation safety. Crack propagation until now has been analyzed using methods such as the Finite Element Method (FEM). These existing methods, however require the subdivision of meshes to be executed every time a crack is to be analyzed after new propagation. This paper proposes a crack propagation analysis method using the Boundary Node Method (BNM). The development of the BNM program for 3-D elastic analysis is presented here along with the results of some of its transverse crack propagation analyses. Source

Chen H.,Track Dynamics Laboratory | Ban T.,Frictional Materials Laboratory | Ishida M.,Track Dynamics Laboratory | Nakahara S.,Tokyo Institute of Technology
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2012

Study on the adhesion of wheel/rail system includes many research fields such as tribology, rolling contact mechanics, material science, structural dynamics, heat transfer and others. The authors focused on several parameters, which play very important roles in the adhesion coefficient of wheel/rail interface. Those parameters are running speed, water temperature, wheel load and surface roughness of the wheel and rail, which have a great influence on hydro-lubrication behavior of water film formed at the wheel/rail interface from the tribological point of view. This paper describes the relation between those parameters and their influence on the adhesion coefficient by means of both theoretical and experimental approaches. Numerical analysis was based on mix-lubrication theory and laboratory experiments were conducted with a twin-disc rolling contact machine. The numerical solutions and the experimental results indicated that the effects of running speed, water temperature and surface roughness of wheel/rail interface on the adhesion coefficient were significant. Source

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