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Suzuki M.,Vehicle Aerodynamics Laboratory | Hibino Y.,Vehicle Dynamics Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute)

Natural winds are turbulent flows and boundary layers exist near the surface of the actual ground, so that there is a possibility that the aerodynamic forces acting on train/vehicles from natural winds differ from uniform flows. Accordingly, full-scale models of a train/ vehicle and a viaduct were constructed in a windy area, and wind characteristics and aerodynamic forces acting on the vehicle models were measured. Wind tunnel tests were conducted to simulate the turbulent boundary layer flow, and these test results agreed well with field tests. Source

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)

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

Shimizu A.,Track Geometry and Maintenance Laboratory | Iida T.,Vehicle Dynamics Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute)

To evaluate running stability, equivalent conicity was computed by considering the combination of a new rail profile and arc wheel profile (for Shinkansen). The new rail profile was obtained by applying the radius of curvature of the top surface of a JIS 50kgN rail, 300 mm. The computation results when using the new rail showed small equivalent conicity and high running stability regardless of the degree of wear of the wheel. Furthermore, results from vehicle dynamics simulations showed that the new rail was endowed with running characteristics equivalent to those of JIS 60kg rail, and no evidence was found of any significant influence on running safety. Source

Watanabe N.,Eunning Gear Laboratory | Maki Y.,Eunning Gear Laboratory | Shimomura T.,Vehicle Dynamics Laboratory | Tohtake T.,Vehicle Dynamics Laboratory | Morishita H.,Eunning Gear Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) (Japan)

Bench tests for existing railcars are effective for measuring their dynamic performance. However, to date it has not possible to duplicate the actual running conditions of one car to a multiple car train consist. This paper explains the development of a hardware-in-the-loop simulation (HILS) system composed of an actual car, a distributed real-time simulator, a real-time network and car end simulators that simulate the dynamic behavior of the end surfaces of adjacent car bodies. This report introduces the HILS system and shows the results of shaking tests on the actual car used to reproduce the running conditions of a three-car train in the HILS system. Source

Purohit B.,Vehicle Dynamics Laboratory | Jain P.C.,Indian Defence Research And Development Laboratory | Pandey A.K.,Vehicle Dynamics Laboratory
Experimental Mechanics

Modal analysis of non-uniform bolted structures are of significance in modeling many complex mechanical structures. There are vast literatures available related with the analytical as well as numerical modeling of bolted joint. However, most of the analytical model discuss about the modeling of first mode of uniform structures with single bolted joint. In this paper, we present the modeling of single as well as bolted non-uniform beams using approximate mode shapes. To develop the model, we first carry out experiments to measures the modal frequencies and shapes of the test structures. Subsequently, we also do numerical modeling of non-uniform beams in ANSYS to verify the validity of the Euler-Bernoulli beam theory in developing the analytical models. Finally, using the Euler-Bernoulli beam theory, we obtain the analytical values of frequencies using the approximate the mode shapes. The analytical results are found to be closer to the experimental results with a maximum percentage error of about 15 %. The model presented in the paper can be extended to the mechanical structures with many non-uniform sections with or without bolted joints. © 2016 Society for Experimental Mechanics Source

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