• 한국철도학회논문집
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• 제11권6호
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• pp.524-529
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• 2008

도시철도 차륜에서 손상된 차륜은 주행 중의 승차감 악화 및 보수비용의 증가로 이어질 수 있기 때문에 차륜답면 특성 변화에 대한 평가는 대단히 중요하다. 본 연구에서는 비파괴적 표면검사법을 이용하여 차륜답면의 손상 평가를 실시하였으며 접촉위치, 주행거리, 제동방식에 따라 차륜답면의 특성을 평가하였다. 그 결과 접촉위치에 따라 차륜답면이 현저히 다른 손상 특성을 나타남을 보여주고 있다.

• 한국자동차공학회논문집
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• 제14권6호
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• pp.95-103
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• 2006

Wheel treads of E.M.U. are usually under a heavy thermal load by brake frictional heat between wheel and brake shoe and damaged by repeated thermal and mechanical loads. To examine the cause of wheel tread damage of E.M.U.'s in service running, a systematic approach has been used. This study is composed of three parts. Frictional heat analysis was conducted in the first part by finite element method. Two kinds of brake shoes in service were considered. In the second part, experimental study was carried out on a brake dynamometer. Temperatures were measured for the two brake shoes. And experimental study in service running E.M.U.'s was performed. Wheel and brake shoe temperatures were measured by using thermocouples and temperature indicating strips. Finally metallurgical characteristics were examined by a SEM/EDS and the cause of the wheel damage was analyzed. It seems that aggregated ferrous component is a main cause of the wheel tread damage.

• 대한기계학회논문집A
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• 제31권7호
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• pp.756-763
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• 2007

The majority of catastrophic wheel failures are caused by surface opening fatigue cracks either in the wheel tread or wheel flange areas. The inclined cracks at railway wheel tread are initiated and the cracks are caused by wheel damage-spatting after 60,000 km running. Because the failured railway wheel is reprofiled before regular wheel reprofiling, the maintenance cost for the railway wheel is increased. Therefore, it is necessary to analyze the mechanism for initiation of crack. In the present paper, the combined effect on railway wheels of a periodically varying contact pressure and an intermittent thermal braking loading is investigated. To analyze damage cause for railway wheels, the measurements for replication of wheel surface and the effect of braking application in field test are carried out. The result shows that the damages in railway wheel tread are due to combination of thermal loading and ratcheting.

• 한국철도학회논문집
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• 제19권5호
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• pp.565-575
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• 2016

철도차량 영업 운행 중 빈번히 발생하는 차륜 마모, 손상 등의 결함을 제거하기 위하여 실시되는 차륜 전삭 공정과 관련하여 전삭 전후의 차량 동적성능을 분석하였다. 전동차를 대상으로 차륜 전삭 전후의 차륜답면형상을 계측, 분석하였으며 진동 및 승차감 특성을 분석하고자 차량 주행시험을 실시하였다. 시험결과, 차륜 전삭 후 차량 진동 RMS값은 전삭 전에 비하여 저감되었으며 철도차량 기술기준에 의거 분석한 차체 진동성능은 전삭 전에 비하여 개선되었다. 승차감레벨은 전삭 전에 비하여 전삭 후 좌우, 상하방향 모두 최대 약 3dB의 개선 효과를 보였으며 주행안전성 또한 개선됨을 확인하였다.

• 한국정밀공학회지
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• 제28권5호
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• pp.537-542
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• 2011

The thermo-mechanical interaction between brake block and wheel tread during braking has been found to cause thermal crack on the wheel tread. Due to thermal expansion of the rim material, the thermal cracks will protrude from the wheel tread and be more exposed to wear during the wheel/block contact than the rest of the tread surface. The wheel rim is in residual compression stress when is new. After service running, the region in the tread has reversed to tension. This condition can lead to the formation and growth of thermal cracks in the rim which can ultimately lead to premature failure of wheel. In the present paper, the thermal cracks of railway wheel, one of severe damages on the wheel tread, were evaluated to understand the safety of railway wheel in running condition. The residual stresses for damaged wheel which are applied to tread brake are investigated. Mainly X-ray diffusion method is used. Under the condition of concurrent loading of continuous rolling contact with rails and cyclic frictional heat from brake blocks, the reduction of residual stress is found to correlate well with the thermal crack initiation.