• International Journal of Railway
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• 제2권2호
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• pp.43-49
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• 2009

Wear and rolling contact fatigue (RCF) defects are most important causes of rail damage, and often interaction competitive at present railway track. Head check is one of rolling contact fatigue (RCF) defects, and generally occurs in mild circular curves and transition curves that are set at both ends of sharp circular curves. Wear tends to limit the crack growth of head checks by removing the material from the RCF surface. In order to clarify the conditions of the occurrence and growth of head checks, the authors measured the interacting forces between wheels and rails and the angle of attack of wheelset, and carried out contact analyses using the actual profile data of wheels and rails. The effects of the lateral force, the contact geometry, and the wear rate at rail gauge comer on the formation of head checks were also analyzed by using the worn profiles of actual wheels and rails and the data obtained by a track inspection car. Some specific range of wear rate at the gauge comer was identified as having close relation with occurrence of head checks.

• 한국철도학회논문집
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• 제11권3호
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• pp.317-325
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• 2008

최근 연구결과 레일연마 및 장대레일화로 누적통과톤수에 의한 레일교체기준의 연장이 가능한 것으로 보고되었다. 본 연구에서는 현재 도시철도에서 사용 중인 대표 궤도구조에 대해 실운행 열차하중에 의한 궤도의 동적 응답을 분석하여 현 궤도의 상태평가를 하였으며 궤도의 상태 변화에 따른 레일의 부담력을 검토하였다. 또한, 측정된 응력파형을 Rainflow Count Method를 이용하여 응력히스토그램을 작성하고 등가응력을 상정하여 신규 레일 용접부의 S-N 선도에 적용함으로써 노후레일의 누적피로손상도 및 휨 피로수명을 산정하였다. 최종적으로 본 연구에서는 궤도구조 및 상태를 고려한 레일교체기준의 개정을 제안하고자 하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.714-719
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• 2004

Railway wheels and axles belong to the most critical components in railway vehicles. The service conditions of railway vehicles became more severe in recent years due to the increase of speed. Therefore, a more precise evaluation of wheel/set life and safety has been requested. One of the major reasons of railway wheel damage is a contact zone failure by wheel/rail contact. In this paper, we conducted a rolling contact fatigue test for wheels using a specimen of wheel/rail. the behavior of hardeness and residual stress below the contact surface of the test pieces in the fatigue process were analyzed. Finally, the relation between fatigue life and contact pressure was obtained.

• 한국기계가공학회지
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• 제12권1호
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• pp.28-34
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• 2013

For the senses of beauty and texture, internal components of small passenger cars are manufactured by texturing plastic with drawplate but those of deluxe passenger cars are manufactured by bonding pre-embossed skin to the surface of drawplate. As the pre-embossed skin is bonded at high temperature and pressure, the pattern of skin is distorted. The corner part is hardened and its dimension tolerance is changed by resulting in the increase with its defective rate. This study provides the method to design and manufacture the door trim track by vacuuming the non-patterned skin to upper-side drawplate which forms the pattern of descending skin. It is pressed to the plastic product with hot-press method and the damage of bossed-pattern is prevented. Valuation in this study has been done by analyzing, designing and experimenting method.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 춘계학술대회 논문집
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• pp.668-673
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• 2003

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. Damages of railway wheel are a spalling by wheel/rail contact and thermal crack by braking heat etc. One of the main source of damage is a residual stress. therefore it is important to evaluate exactly. A Residual stress of wheel is formed at the process of heat treatment when manufacturing. it is changed by contact stress developed by wheel/rail contact. Distributions of residual stress vary according to a magnitude of wheel load, a magnitude of friction when acceleration and deceleration. The objective of this paper is to estimate the influence of wheel motion on the residual stress distribution in the vicinity of the running surface.

• 한국철도학회논문집
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• 제6권2호
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• pp.142-148
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• 2003

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. Damages of railway wheel are a spatting by wheel/rail contact and thermal crack by braking heat etc. One of the main source of damage is a residual stress. therefore it is important to evaluate exactly. A Residual stress of wheel is formed at the process of heat treatment when manufacturing. it is changed by contact stress developed by wheel/rail contact. Distributions of residual stress vary according to a magnitude of wheel load, a magnitude of friction when acceleration and deceleration. The objective of this paper is to estimate the influence of wheel motion on the residual stress distribution in the vicinity of the running surface.

• International Journal of Railway
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• 제2권1호
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• pp.18-21
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• 2009

The basis of modem risk-based safety management is to focus on what might happen and ensure it is designed out of the system by robust hazard identification and risk analysis. However, in the real world things go wrong and it is essential to be prepared for the worst so that the response can minimise harm and loss of property and damage to the environment. Whilst some hazard mitigation measures are aimed at preventing incidents, others are venting escalation. The results of the tests concluded that the most effective means by the control room, both with and without, local station staff assistance using directive public address announcements and CCTV surveillance.

• 한국정밀공학회지
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• 제31권9호
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• pp.783-790
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• 2014

Railway wheels and axles are the most critical parts of the railway rolling stock. The wheel carry axle loads and guide the vehicles on the track. Therefore, the contact surface of wheel are subjected to wear and fatigue process. The wheel damage can be divided into three types; wear, contact fatigue failure and thermal crack due to braking. Therefore, in the contact surface between the wheel and the rail, the materials are heat treated to have a specific hardness. The manufacturing quality of the wheel have a considerable influence on the formation of tread wear and damage. Also, the residual stress on wheel is formed during the manufacturing process is one of the main sources of the damage. In this paper, the mechanical characteristic and the residual stress according to wheel material have been evaluated by applying finite element analysis and conducting mechanical tests.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.692-697
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• 2004

Damage often occurs on the surface of railway wheel by wheel-rail contact fatigue. It should be removed before reaching wheel failure, because wheel failure can cause derailment with loss of life and property. The increase or decrease of the contact fatigue life by the metal removal of the contact surface were shown by many researchers, but it has not explained precisely why fatigue life increases or decreases. In this study, the effect of metal removal depth on the contact fatigue life for railway wheel has been evaluated by applying finite element analysis. It has been revealed that the residual stress and the plastic flow are the main factors determining the fatigue life. Finally, the contact fatigue life according to metal removal has been estimated.

• 한국산업융합학회 논문집
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• 제26권2_2호
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• pp.341-347
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• 2023

The subway is one of the most common and important means of transportation in modern society. In order to use the subway safely, tracks are necessary, but trains are prone to derailment and collisions. In order for the train to run safely on the track, the fishplate that connects the line connection is used. The damaged railway was a fishplate for connecting subway lines used for 11 years, and damage analysis and countermeasures were presented. Beach marks were observed on both fracture surfaces, and striations appeared at the range of crack propagation. The damaged part is Cr carbide, which has a higher hardness than the base metal, and is judged to be embrittled and destroyed by fatigue. The SM50C fishplate was subjected to a cyclic stress of about 59% of the upper limit of tensile-compression fatigue limit, but inclusions were the cause of failure. In order to prevent fatigue failure of the SM50C steel fishplate, the occurrence of inclusions should be minimized and processed to have a homogeneous structure when manufacturing the fishplate. In addition, compressive residual stress is given through surface modification such as peening to control crack generation. It is necessary to minimize the change in shape that can become a stress concentration part along with accurate fastening of the bolt, and to design the stress distribution to be as uniform as possible.