• Journal of KSNVE
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• v.9 no.6
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• pp.1259-1266
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• 1999

The objective of this investigation is to develop a compliant track link model and apply this model to the multi-body dynamic analysis of high mobility tracked vehicles. Two major difficulties encountered in developing the compliant track models. The first one is that the integration step size must be kept small in order to maintain the numerical stability of the solution. This solution deals with high oscillatory signals resulting from the impulsive contact forces and stiff compliant elements to represent the joints between the track links. The second difficulty is due to the large number of the system equations of motion of the three dimensional multibody tracked vehicle model. This problem was sloved by decoupling the equations of motion of the chassis subsystem and the track subsystems. Recursive methods are used to obtain a minimum set of equations for the chassis subsystem. Several simulation scenarios were tested for the high mobility tracked vehicle including accelaeration, high speed cruising, braking, and turning motion in order to demonstrate the effectiveness and validity of the methods proposed in this investigation.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.337-342
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• 2003

The dynamic load effects are conveyed to the railway bridges through tracks which are generated by moving trains The dynamic load effects may vary due to the dynamic characteristics of the applied vehicle loads and the railway bridges containing the track system. However, the track effects have been neglected or simplified by spring elements in the most studies since it is quite complex to consider the track systems in the dynamic analysis models of railway bridges. In this study, track system on railway bridges is modeled using a three-dimensional discrete-support model that can simulate the load carrying behavior of tracks. In addition, this program is developed with the precise 20-car model and a continuous PSC(prestressed concrete) box girder bridge, which is the main bridge type of Korea Train express(KTX). Three-dimensional elements are used for both. The dynamic response of railway bridges is found to be affected depending on whether the track model is considered or not. The influencing rate depends on the traveling speed and different wheel-axle distance. The dynamic bridge response is decreased remarkably by the track systems around the resonant frequency. Therefore, the resonance effect can be reduced by modifying the track properties in the railway bridge.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.479-484
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• 2005

Comparison it analyed the tunnel travelling hour interior noise arresting quality of the inside and outside of the country high-speed vehicle from the research which it sees. In the interior sound arresting comparison objective vehicle of the tunnel travelling hour KTX vehicle from the research which it sees and it limited by the TGV vehicle of France and the ICE vehicle og Germany and the Shinkansen vehicle of Japan comparison it analyzed the interior sound arresting from the open field and the tunnel line. The tunnel passage hour interior sound arresting problem of the domestic KTX vehicle follows in the concreate track tunnel the ballast track tunnel and the interior sound arresting quality is appearing different.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6D
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• pp.663-671
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• 2012

The demand of CWR is rapidly increasing because of the adaptation of concrete track, the need for rapid and comfortable ride, and the reduction of maintenance cost. Because of short applying period of the concrete track, there is not a case of CWR fracture in Korea caused by repeated load of the train, which makes it difficult to calculate replacement period of rail based on rail fatigue life using an actual field data. This study thus inspected the bending stress at rail bottom through analyzing the vehicle/track interaction, performed multiple regression analysis on the data, deducted the bending stress prediction equations by the speed and the surface irregularity. Finally, the fatigue life of CWR on the concrete track was predicted based on the prediction equations for bending stress at rail bottom.

• Journal of the Korean Society for Railway
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• v.16 no.2
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• pp.110-116
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• 2013

Track irregularities is one of the key factors influencing the running behavior of trains. In order to ensure safety and ride comfort of train, the criteria for track irregularities should be adequately established regarding vehicle velocity, vehicle characteristics, characteristics of the track recording car, and measurement interval. Also, track maintenance should be carried out thoroughly according to the criteria for managing track irregularities. Numerical analysis was conducted to investigate the influence of track alignment on the running behavior of Korean high speed train(KTX). Various wavelengths and amplitudes of lateral alignment were considered as parameters for this study using the Vampire program, a vehicle dynamics modeling package in railway environment. Derailment, lateral load, bogie acceleration and body acceleration of numerical analysis results due to alignment were investigated. Finally, the influence of the alignment on safety and ride comfort for the KTX was evaluated. This study indicates that alignment irregularities have significant impacts on running safety, and that the criteria used to manage alignment irregularities should be restrictive to ensure the running safety of the KTX.

• Wind and Structures
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• v.29 no.5
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• pp.299-312
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• 2019

Due to the rugged terrain, metro lines in mountain city across numerous wide rivers and deep valleys, resulting in instability of high-pier bridge and insecurity of metro train under crosswind. Compared with the conditions of no-wind, crosswind triggers severer vibration of the dynamic system; compared with the short-pier viaduct, the high-pier viaduct has worse stability under crosswind. For these reasons, the running safety of the metro vehicle traveling on a high-pier viaduct under crosswind is analyzed to ensure the safe operation in metro lines in mountain cities. In this paper, a dynamic model of the metro vehicle-track-bridge system under crosswind is established, in which crosswind loads model considering the condition of wind zone are built. After that, the evaluation indices and the calculation parameters have been selected, moreover, the basic characteristics of the dynamic system with high-pier under crosswind are analyzed. On this basis, the response varies with vehicle speed and wind speed are calculated, then the corresponding safety zone is determined. The results indicate that, crosswind triggers drastic vibration to the metro vehicle and high-pier viaduct, which in turn causes running instability of the vehicle. The corresponding safety zone for metro vehicle traveling on the high-pier is proposed, and the metro traffic on the high-pier bridge under crosswind should not exceed the corresponding limited vehicle speed to ensure the running safety.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1922-1928
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• 2011

The rail inclination produces a wider bearing area between the wheel and the rail by moving the wheel rail contact area away from the gauge towards the centre of the railhead, thus improving the wear pattern of the railhead and wheel treads. It is essential to keep the rail inclination within the allowable range to ensure optimum track geometry. Neglecting the rail inclination geometrical parameters in a track quality evaluation can cause safety of railway vehicle and serviceability problems. In this paper, we examined the effect of the rail inclination in general geometry state of the railway track using VI-Rail and analyzed running safety when the railway vehicle passing through curves depending on change of the rail inclination and running speed.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.04a
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• pp.68-75
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• 1997

This paper presents a new approach to the design of neural-fuzzy controller for the speed and azimuth control of a track vehicle. The proposed control scheme uses a Gaussian function as a unit function in the frzzy-neural network, and back propagaton algorithm to train the fuzzy-neural network controller in the framework of the specialized learning architecture. It is proposed a learning controller consisting of two neural network-fuzzy based on independent reasoning and a connection net with fixed weights to simply the neural networks-fuzzy. The performance of the proposed controller is shown by performing the computer simulation for trajectory tracking of the speed and azimuth of a track vehicle driven by two independent wheels.

• Proceedings of the KSR Conference
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• 2001.05a
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• pp.295-302
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• 2001

The lateral stability of curved continuous welded rail (CWR) is studied fur buckling prevention. This study includes the influences of vehicle induced loads on the thermal buckling behavior of straight and curved CWR tracks. quasi-static loads model is assumed to determine the uplift region, which occurs due to the vertical track deformation induced by wheel loads of vehicle. Parametric numerical analyses are performed to calculate the upper and lower critical buckling temperatures of CWR tracks. The parameters include track lateral resistance, track curvature, longitudinal stiffness, tie-ballast friction coefficient, axle load, truck center spacing, and the ratio of lateral to vertical vehicle load. This study provides a guideline for the improvement or stability for dynamic buckling in on tracks.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.05a
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• pp.210-215
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• 1999

In this paper, a new approach to the dynamic control technique for track vehicle system using fuzzy-neural network control technique is proposed. The proposed control scheme uses a Gaussian function as a unit function in the neural network-fuzzy, and back propagation algorithm to train the fuzzy-neural network controller in the framework of the specialized learning architecture. It is proposed a learning controller consisting of two neural network-fuzzy based on independent reasoning and a connection net with fixed weights to simply the neural networks-fuzzy. The performance of the proposed controller is shown by simulation for trajectory tracking of the speed and azimuth of a track vehicle.