• International Journal of Railway
• /
• v.5 no.2
• /
• pp.93-101
• /
• 2012

Owing to the lightening of railway vehicles and increased operation speeds, the reduction of running safety in the presence of crosswind is becoming an important problem. In particular, the running safety tends to decrease when vehicles run on curved track. When a crosswind acts on a vehicle negotiating a curve from the outer side, flange climbing can occur. In this study, a full-vehicle model was constructed using the multi-body simulation software SIMPACK, and a simulation of a bogie vehicle with two-axle trucks negotiating a curve was carried out to examine the running safety under the condition where a crosswind acts on the vehicle from the outer side of the curve. As a result, it was verified that the derailment coefficient of the first wheelset becomes large in the exit transition curve and the coefficient of the third wheelset does in the entrance transition curve, and this trend becomes pronounced at low operation speeds in the presence of a stronger crosswind. It was also shown that the critical derailment coefficients obtained by modified Nadal's formula considering the effect of attack angle become close to the actual derailment coefficients at the timing that flange climbing occurs.

• Proceedings of the KSR Conference
• /
• 2004.10a
• /
• pp.467-471
• /
• 2004

The development of a tilting train with construction of electric line on the conventional railway is required for speed-up on the conventional railway with many curving sections. For development of tilting train, the study and development of the tilting system and tilting bogie having the different mechanism with a general high speed train will play a main role for improving the technology in the field of Korean railway. The study and development of the pantograph tilting mechanism in order to keep a good contact behavior between a pantograph and a contact wire by tilting a pantograph on the opposite direction of the vehicle tilting direction. In this study, we analyzed the aerodynamic characteristic of a developing pantograph on the tilting train and obtained the contact force with catenary by aerodynamic lift force by the aerodynamic analysis. We also performed the numerical analysis for design the device controlling lift force on a pantograph. From the aerodynamic simulation and parameter study for a device to control the lift force, we will suggest the various shape and the optimal shape of it corresponding to a developing tilting pantograph. The Fluent software is used for the calculation of flow profile in this study.

• Journal of the Korean Society for Railway
• /
• v.13 no.6
• /
• pp.583-588
• /
• 2010

Track irregularities is one of key factors influencing running behavior of train. In order to ensure safety and ride comfort, it is highly important that relationship between track irregularity and running behavior of vehicle is identified and the criteria for track irregularities is adequately established. Numerical analysis was conducted to investigate influence of surface on running behavior of KTX and various wavelength and amplitude of surface were considered in numerical analysis. Derailment, lateral load, bogie acc., body acc. of numerical analysis results were investigated to evaluate the effect on track profile on safety and ride comfort of KTX.

• Proceedings of the KSR Conference
• /
• 2003.05a
• /
• pp.567-573
• /
• 2003

Korean High Speed Train (KHST) has been tested on high speed line in JungBu site since it was developed in 2002. The data acquisition system was developed to accomplish successfully this on-line test for proving the dynamic Performance of KHST. This system was consist of the personal computers based on National Instrument PXI modules and the test programs based on Labview 6i. This paper shows that this system is efficient to acquire the test data through the multi-channels connected the accelerometers which located in long distance places and flexible to change and add channels for data acquisition. The dynamic analysis of an on-line test is very complicate because the environmental conditions, as examples radius of curve, inclination of the track, tunnels, bridges, and so forth, and running conditions, as examples driving, braking, the number of working motors, and so forth, have an effect on the results. Therefor, the analysis method is important and this paper proposes the efficient procedure graphically, showing the proposed method simplify the accelerations of 5th bogie frame acquired during the on-line test for KHST.

• Journal of the Korean Society for Railway
• /
• v.8 no.6 s.31
• /
• pp.500-506
• /
• 2005

The development of tilting train has been required for speed-up on the conventional electric railroad due to the characteristic of Korean railroad with a lot of curve track. The study and development of a tilting system and a tilting bogie which have a different mechanism with high speed train will play a important role for enhancement of technology for Korean railway. The study for tilting pantograph mechanism to decrease the displacement between a catenary and a center of pantograph happened when the carbody is tilted in order to maintain the ride comfort and stability m a curving track is proceeding with the development of tilting train. In this paper, we introduce the design concept for the tilting mechanism of pantograph and the role and characteristics for several devices adopted in the tilting mechanism of pantograph. Through the kinematic analysis of tilting mechanism, we will obtain and calculate the optimal tilting angular velocity and acceleration in order to keep the contact behavior of a pantograph and a catenary according to tilting of a carbody.

• International Journal of Railway
• /
• v.1 no.2
• /
• pp.31-36
• /
• 2008

$DF_{21}$ diesel locomotive was designed to satisfy the requirement of Kunming Meter track and the 2Co self-guided radial bogie was used to suit the complex curve track. There are totally 12 locomotives was served on the track. The first two locomotives were devotion running on the track since April 2003, the wheel tread splling was occurred on the middle wheel set of the two locomotives after running nearly 150 thousands km on the track of the two locomotives at August 2004. The dynamic analysis was carried out to find the reason. The wheel set longitudinal vibration resonance phenomenon was existed on the locomotive dynamic performance, and this was caused by the too big longitudinal stiffness of the journal box bar on the middle wheel set. Wheel set longitudinal vibration resonance maybe an important reason of lead to wheel tread spalling. The corresponding mend methods were put forward from the point of view of wheel set longitudinal vibration resonance. All the wheel tread of the 12 locomotives on the middle wheel set were in good condition and not occurred the wheel tread spalling after the mend till December 2007 after 350 thousands km were finished. The mechanism of the wheel tread splling and corresponding mend method was discussed in detail in this paper.

• Journal of the Korean Society of Safety
• /
• v.31 no.3
• /
• pp.28-33
• /
• 2016

Since defects in the wheels of railway vehicles, which occur due to wears with the rail, cause serious damage to the running device, the diagnostic monitoring system for condition-based maintenance is required to secure the driving safety. In this paper, we studied to apply a useful Cepstrum analysis to detect periodic structure in spectrum among the vibration signal processing techniques for the fault diagnosis of a rotating body such as wheel. In order to analyze in variations of train velocity, the Cepstrum analysis was performed after a domain change of the vibration signal from time domain to rotation angle domain. When domains change, it is important to use a interpolation for a uniform interval of the rotation angle. Finally, the Cepstrum analysis for wheel flat detection was verified by using the vibration signal including the disturbance resulting from the rail irregularities and the vibration of bogie components.

• Journal of the Korean Society for Precision Engineering
• /
• v.30 no.10
• /
• pp.1051-1059
• /
• 2013

In general, lateral ride comfort of railway vehicle is mainly influenced by a secondary suspension placed between the bogie and carbody. Higher operating speeds of train results in increased vibration of carbody, which has a negative impact related to the ride comfort. To solve this problem, researches to replace the conventional passive suspension with (semi)active technology in the secondary suspension of a railway vehicle have been carried out. The semi-active suspension using the magneto-rheological damper is relatively simpler system and has advantage in maintenance compared to the hydraulic type semi-active damper. This study was performed to reduce lateral vibration acceleration of carbody related to ride comfort of railway vehicles with a semi-active suspension system. The numerical analysis was conducted by replacing passive lateral damper with semi-active MR damper, and robust control with the MR damper was applied to the 1/5 scaled railway vehicle model.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.21 no.7
• /
• pp.637-642
• /
• 2011

The DMT freight is judged that economic performance is good because can increase cargoes than existing freight. However, the existing freight cars, each with a different balance to the body structure is bogie because the vibrations may occur. Thus, by minimizing vibration over the existing freight securing the safety of the driving if you will not have major problems in cargoes. In this study, multi-body dynamic analysis tool, VI-Rail using the actually Gyeongbu Railroad line and an empty, full freight condition include curve radius, track irregularity, The DMT freight of the derailed wagons were assessed for safety analysis. Full and empty freight conditions for parity in the Gyeongbu Railroad line(Dongdaegoo${\leftrightarrow}$Kyungsan) derailment safety analysis, such as derailment coefficient and the wheel unloaded, echoing the curve and the orbit is affected by the irregularity was found. Full freight condition than the empty conditions showed a significant derailment safety. Overall, the limits of derailment coefficient(Q/P = 0.8) and wheel unload decrement limits(${\triangle}P/P$ = 0.6) is less safe with me confirmed that the derailment safety.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.30 no.2
• /
• pp.116-120
• /
• 2010

The wheelset, an assembly of wheel and axle, is one of important parts in railway bogie, directly related with the running safety of railway rolling stock. In this investigation, the tensile failure behavior of railway axle materials was investigated. The tensile coupons were prepared from the actual rolling stock parts, which were operated over 20 years. The tensile testing was performed according to the KS guideline. During tensile testing, an infrared camera was employed to monitor temperature changes in specimen as well as demonstrate temperature contour in terms of infrared thermographic images. The thermographic images of tensile specimens showed comparable results with mechanical behavior of tensile materials. In this paper, the failure mode and behavior of railway axle materials were provided with the aid of infrared thermography technique.