• 한국안전학회지
• /
• 제27권4호
• /
• pp.43-49
• /
• 2012

In the design of high speed railway bridges is important a impact factor as a tool of assessing the dynamic capacitys of bridges. However, the impact factor(or dynamic amplification factor, DAF) of high speed railway bridges may essentially be changeable because the dynamic response is affected by the long train length(380 m), number of axles and high speed velocity(300 km/h)(Korea Train eXpress: KTX). Therefore, on this study will be examined the dynamic capacity and stability of the typical PSC Box Girder of high speed railway bridge. At first, the static/dynamic analysis is performed considering the axle load line of KTX based upon existing references. Additionally, the KTX moving load is transformed into the dynamic time series load for conducting various parameter studies like axle length, analytical time increment, velocity of KTX. The time history analysis is repeatedly performed to get maximum dynamic responce by varying axle load length, analytical time increment, velocity of KTX. The study shows that dynamic analysis has resonable results with optimal axle load length(0.6 m) and time increment(0.01 sec.) and maximum DAF and dynamic resonance happens at 270 km/h velocity of KTX.

• 한국생산제조학회지
• /
• 제26권4호
• /
• pp.436-440
• /
• 2017

This study evaluated the design and structural integrity of a three-axle bogie frame in a railway freight car through a numerical analysis and an experimental evaluation. A three-axle bogie frame, which supports the weight of the car body and load, is required to transport heavier cargo because two-axle vehicles have structural limitations. Therefore, this study performed a structural analysis and static load tests to evaluate the design and structural integrity of a three-axle bogie frame. The results obtained from the numerical analysis were compared to those of the experiments. For the bogie frame used in the experiments, a failure evaluation was performed using non-destructive methods. The numerical analysis and experimental evaluation were satisfactory for the structural integrity evaluation.

• 한국정밀공학회지
• /
• 제27권8호
• /
• pp.28-34
• /
• 2010

Railway wheel and axle is the most critical components in railway system. A wheel and axle failure can cause a derailment with its attendant loss of life and property. The service conditions of railway vehicles have become severe in recent years due to a general increase in operating speeds. Therefore, more precise evaluate of wheelset strength and safety has been desired. Fracture mechanics characteristics such as dynamic fracture toughness, fatigue threshold and charpy impact energy with respect to the tread, plate, disc hole of wheel and the surface of press fitted axle are evaluated. This paper describes the difference of fracture toughness, fatigue crack growth and fatigue threshold at the locations of wheel and axle. The results show that the dynamic fracture toughness, $K_{ID}$, is obviously lower than static fracture toughness, $K_{IC}$ and the fracture mechanics characteristics are difference to the location of wheel tread and hole.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2005년도 춘계학술대회 논문집
• /
• pp.397-402
• /
• 2005

The NDT(Non-Destructive Testing) is valid for the defect detection of rolling stocks because it can be used to detect the defect in many invisible parts. For example, fatigue cracks are initiated in press fit parts that suffer from fretting fatigue damage such as the wheel seat and the NDT technique can detect those cracks. But the conventional ICFPD method can not apply to detect such cracks in press fit parts of the axle by some technical problems. In this study, we have introduced the new concept ICFPD method that can be applied in press fit parts of the axle. And we have shown the basic techniques of FEM about the new concept ICFPD method.

• 한국자동차공학회논문집
• /
• 제15권5호
• /
• pp.139-145
• /
• 2007

Fretting is a kind of surface damage mechanism observed in mechanically jointed components and structures. The initial crack under fretting damage occurs at lower stress amplitude and lower cycles of cyclic loading than that under plain fatigue condition. This can be observed in automobile and railway vehicle, fossil and nuclear power plant, aircraft etc. In the present study, railway axle material RSA1 used for evaluation of fretting fatigue life. Plain and fretting fatigue tests were carried out using rotary bending fatigue tester with proving ring and bridge type contact pad. Through these experiments, it is found that the fretting fatigue limit decreased about 37% compared to the plain fatigue limit. In fretting fatigue, the wear debris is observed on the contact surface, and oblique cracks at an earlier stage are initiated in contact area. These results can be used as useful data in a structural integrity evaluation of railway axle.

• 한국자동차공학회논문집
• /
• 제18권2호
• /
• pp.74-82
• /
• 2010

Fretting damage can be observed in automobile and railway vehicle, fossil and nuclear power plant, aircraft etc. In the present study, railway axle material RSA1 used for evaluation of fretting fatigue life. Plain and fretting fatigue tests were carried out using rotary bending fatigue tester with proving ring and bridge type contact pad. Through these test, the following results are obtained: 1) it is found that the fretting fatigue limit of standard specimen decreased about 37% compared to the plain fatigue limit. 2) The early crack of Shinkansen type specimens initiated in contact area and final fractured below samp=214 MPa. 3) The early crack of all TGV type specimens initiated in rounded area and fractured. 4) Tire tracks and rubbed scars were observed in the oblique crack region and fatigue crack growth region of fracture surface. 5) The wear debris is observed on the contact surface, and oblique cracks at an earlier stage are initiated in contact area. These results can be used as useful data in a structural integrity evaluation of railway axle.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 추계학술대회 논문집
• /
• pp.24-27
• /
• 2005

The NDT(Non-Destructive Testing) is valid fur the defect detection of rolling stocks because it can be used to detect defects in invisible places. For example, in case of wheelsets fatigue cracks are initiated in the wheel seat that suffers from fretting fatigue damage. But the conventional ICFPD method can not be applied to detect such cracks in press-fit area of the axle by some technical problems. In this study, we introduced a new ICFPD (Induced Current Focusing Potential Drop) method that can be applied in press-fit area of the axle. And we performed the finite element analysis of the new ICFPD method using measured electromagnetic properties of the wheel and axle. It seems that our approach is very useful f3r the detection of defects in invisible places.

• 한국산학기술학회논문지
• /
• 제14권6호
• /
• pp.2581-2587
• /
• 2013

철도차량의 안전성을 위해 사용되는 윤축은 차량 전체 중량의 16%를 차지하는 요소로서, 철도차량의 경량화에 있어 필수적으로 연구되는 대상이다. 본 연구는 기존 윤축의 중량을 요구강도에 만족시킴과 경량화를 목적으로 창의적 문제해결이론인 TRIZ의 6SC를 적용하여 중공구조의 윤축 내부에 사용될 수 있는 캡을 설계하였고, 설계에 대한 검증을 위해 해석 툴인 ANSYS를 활용하였다. 본 연구에서 제안한 캡의 재질은 SM45C이며 중공구조이다. 또한, 윤축에 요구되는 강도를 만족하기 위해 중공 윤축의 베어링 시트 부 내부에 위치한다. 본 연구를 통해 설계 및 해석된 캡을 삽입한 윤축은 전동차의 윤축에 요구되는 기준을 만족하였으며 무게는 중실축과 비교하였을 때, 약 6.75%를 감소시켰다. 윤축 강도에 대한 평가 기준은 EN13103 및 EN13104의 규격을 적용하였다. 또한, 캡을 장착한 윤축의 최대응력 및 중량에 대해 기존의 중실축, 중공축과 비교함으로써 설계에 대한 효과를 검증하였다.

• 전기학회논문지
• /
• 제65권4호
• /
• pp.695-703
• /
• 2016

The maintenance method for the electrical facility of high speed railway has been evolved from inspection by personnel to the automated way by the detection devices. In particular, the signalling equipment in order to increase the safe and efficient operation of the trains is required to maintain normal operation by periodic maintenance. Because the return current gives the most important effects to the wayside equipment in case of the failures, a method is needed to measure the unbalanced rate of return current on the train at high speed driving. The Hot Box Detector(HBD) device that is installed at track-side has a function to recognize the abnormal axle box by detecting the temperature that occurs in the axle of train passing over its device. In order to implement the measurement equipment for unbalanced rate of return current and axle temperature, the design method is proposed and the experimental test results by test bed are included in the paper.

• Structural Engineering and Mechanics
• /
• 제13권5호
• /
• pp.505-532
• /
• 2002

In this study, the analysis of high-speed vehicle-bridge interactions by a simplified 3-dimensional finite element model is performed. Since railroads are constructed mostly as double tracks, there exists eccentricity between the vehicle axle and the neutral axis of cross section of a railway bridge. Therefore, for the more efficient and accurate vehicle-bridge interaction analysis, the analysis model should include the eccentricity of axle loads and the effect of torsional forces acting on the bridge. The investigation into the influences of eccentricity of the vehicle axle loads and vehicle speed on vehicle-bridge interactions are carried out for two cases. In the first case, only one train moves on its track and in the other case, two trains move respectively on their tracks in the opposite direction. From the analysis results of an existing bridge, the efficiency and capability of the simplified 3-dimensional model for practical application can be also verified.