• Title, Summary, Keyword: Rail stress

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Residual Stress Analysis of Repair Welded Rail Using the ABAQUS User Subroutine (ABAQUS 서브루틴을 이용한 레일 보수용접 잔류응력 해석)

  • Kim, Dong Wook;Jun, Hyun Kyu;Lee, Sang Hwan;Chang, Yoon Suk
    • Journal of the Korean Society for Precision Engineering
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    • v.33 no.7
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    • pp.551-558
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    • 2016
  • Reduction of welding residual stress is very important in the railway industry, but calculating its distribution in structures is difficult because welding residual stress formation is influenced by various parameters. In this study, we developed a finite element model for simulating the repair welding process to recover a surface damaged rail, and conducted a series of parametric studies while varying the cooling rate and the duration of post weld heat treatment (PWHT) to find the best conditions for reducing welding residual stress level. This paper presents a three-dimensional model of the repair welding process considering the phase transformation effect implemented by the ABAQUS user subroutine, and the results of parametric studies with various cooling rates and PWHT durations. We found that heat treatment significantly reduced the residual stress on the upper rail by about 170 MPa.

An Experimental Study on Causes Evaluation of Rail Corrugation for Concrete track(STEDEF) in Urban Transit (도시철도 콘크리트궤도(STEDEF)의 레일파상마모 발생원인 분석을 위한 실험적 연구)

  • Choi, Jung-Youl;Gong, Hyung-Sik;Kim, Jun-Hyung;Kim, Hak-Seon;Chung, Jee-Seung
    • The Journal of the Convergence on Culture Technology
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    • v.4 no.4
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    • pp.413-418
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    • 2018
  • The purpose of this study is to investigate the cause of rail corrugation and the track force for concrete track (STEDEF) in the urban transit. From the field measurements, the dynamic wheel load, vertical displacement of sleeper and rail bending stress were measured and it was evaluated by regarding to the rail corrugation. As a result of the study, the causes of rail corrugation was experimentally proved by frequency analysis using measured dynamic wheel load data. The influence of corrugation on dynamic wheel load, rail bending stress and sleeper displacement was evaluated that the periodic irregularities of rail corrugation on the rail surface amplified the dynamic track force such as the dynamic wheel load, and thus the rail bending stress and the vertical displacement of sleeper could be increased by a maximum of 1.7 times.

Safety Evaluation on Interaction between Track and Bridge in Continuous Welded Railway Bridge Considering Seismic Load (지진하중을 고려한 장대레일교량의 궤도-교량 상호작용에 대한 안전성 평가)

  • Shim, Yoon-Bo;Kim, Yun-Tae;Kim, Sang-Chel
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.20 no.2
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    • pp.40-48
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    • 2016
  • To observe the rail-slab interaction in continuous welded railway(CWR) bridge when earthquake occurs, additional axial rail stresses and relative longitudinal displacements between rail and bridge deck were calculated with input of various load combinations and 3 different types of seismic loads to an analytical model. As results of analysis, it can be found that standard response spectrum proposed by Korea Rail(KR) network authority for earthquake design showed less additional axial rail stresses than allowable levels, but greater relative longitudinal displacement between rail and bridge deck, which means that adjustment of relative longitudinal displacement within a standard level is much more difficult than axial train stress. Additionally, if a large-scaled earthquake as occurred at Kobe, Japan comes up, then both of additional axial rail stress and relative displacement in rail-bridge deck may exceed allowable levels, which indicates to make proper design guides against sudden earthquake occurrence.

Design of a Roller Rail for the Drawer of Three-Door Refrigerators Using Taguchi Method (다구찌 기법을 이용한 3 문형 냉장고 서랍용 롤러 레일의 설계)

  • Lee, Boo-Youn;Kim, Je-Hyun
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.6
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    • pp.97-105
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    • 2009
  • Optimal design of a roller rail which replaces the ball rail for three-door refrigerators is presented using the finite element analysis and the Taguchi method. Stress and deformation of the roller rail for an initial design are analyzed and evaluated. Optimal design parameters are determined using the Taguchi method. The maximum stress of the optimal design is favorably reduced comparing to the initial design. It is verified through an additional analysis that the drawer on the roller rail will not be derailed even if one opens the drawer with a transverse force.

Analysis of Track-Bridge Interaction and Retrofit Design for Installation of CWR on Non-ballasted Railway Bridge (무도상 철도교 레일 장대화를 위한 궤도-교량 상호작용 해석 및 개량방안 분석)

  • Yoon, Jae Chan;Lee, Chang Jin;Jang, Seung Yup;Choi, Sang Hyun;Park, Sung Hyun;Jung, Hyuk Sang
    • Journal of The Korean Society For Urban Railway
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    • v.6 no.4
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    • pp.383-392
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    • 2018
  • This study investigated the change of additional axial stress of rail and reaction force at bridge bearings due to the track-bridge interaction when laying CWR on non-ballasted railway bridges including truss bridges with relatively long span. According to the results of the present study, additional axial stresses of rail and reaction forces at bridge bearings showed a large increase when CWR is installed on the non-ballasted railway bridge. The additional axial stress of rail can be acceptable if sufficient lateral resistance can be obtained. However, if the reaction force increases, there is a risk of damage of the bearing or pier, and therefore, it is necessary to take measures to mitigate the reaction force. It is found that additional axial stress of rail decreases when considering the frictional resistance of the bridge movable support, but its effect on the bearing reaction force is very small. On the other hand, when the longitudinal track restraint decreases, both additional axial stress of rail and bearing reaction force are reduced to a large extent. Also, when the ZLR fastening devices are applied to the region where the additional axial stress of rail is highest, bearing reaction force as well as additional axial stress of rail greatly decreased. Therefore, the application of ZLR fastening devices with the reduction of the longitudinal track restraints is very effective for installing CWR on non-ballasted railway bridges.

Stress Distribution of Tilting Vehicles Wheel-set by Interaction Force Between Wheel and Rail (차륜과 레일간의 상호 작용력에 의한 틸팅차량 윤축의 응력분포)

  • Ham Y.S.;Oh T.Y.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.363-364
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    • 2006
  • The important factor to evaluate the running safety of a railway vehicle would be the interaction force between wheel and rail(derailment coefficient), for which is one of important factors to check the running safety of a railway vehicle that may cause a tragic accident. In this paper, when interaction force between wheel and rail happens to wheel-set of tilting vehicles, it analyzes stress distribution and verified safety.

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Fracture Criterion and Fatigue Crack Growth Behavior of Rail Steel Under Mode I & Mixed Mode Loading (단일 및 혼합모드 하중하에서의 레일강의 파괴조건 및 피로균열진전거동)

  • Kim, Jung-Kyu;Lee, Jong-Sun;Kim, Chul-Soo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.23 no.6
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    • pp.1039-1047
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    • 1999
  • It is necessary to evaluate the fatigue behavior of rail steel under the multi-axial stress state to assure the railway vehicle's safety. For this purpose, the stress analysis to investigate the crack initiation criteria, static failure and fatigue behavior under mixed-mode are performed. The stress analysis results show that the initiation of the transverse fissure depends on the maximum shear stress below the surface. For the mixed mode, the fatigue crack growth behavior which is represented by the projection crack length and comparative S.I.F, ${\Delta}K_v$, shows the more conservative results. Also, its rate is lower than that of the case of the mode I, and this difference decreases with increasing the stress ratio, R.

Evaluation on Effectiveness of Rail Grinding by Prediction of Rail Fatigue Life (레일 피로수명 예측에 따른 레일 연마의 효용성 평가)

  • Kim, Man-Cheol
    • Proceedings of the KSR Conference
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    • pp.255-261
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    • 2008
  • The importance of maintenance of rail surface defects is increasing according to the KTX operation. That is because during high speed operation of rolling stocks, rail surface defects shorten fatigue life of rail, accelerate track degradation and deteriorate ride comfort. Rail grinding has been applied for effective rail maintenance in Kyeong-Bu HS line. This paper evaluates the effectiveness of rail grinding in term of rail fatigue life. To this end, the stresses of the ground rail are measured under KTX running and the equivalent stress range is calculated by RMC after the frequency analysis done with Rainflow counting method. Also, Pamglen-Miner rule is applied to predict the fatigue life of ground rail. The result of the analysis shows that the fatigue life of ground rail is increased by 15%.

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Contact Stress Analysis on the Variation of Wheel Profile (차륜답면의 형상변화에 의한 접촉응력분포 해석)

  • Kim Eui-Seok;Hur Hyun-Mo;Yun Chun-Han
    • Proceedings of the KSR Conference
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    • pp.663-667
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    • 2003
  • Mechanical force acted on the rail wheel causes excessive wear and increases the maintenance cost. The present paper proposes newly designed wheel profiles in order to reduce the contact stress. Numerical analysis on the stress distribution of wheel-rail contact stress is carried out using ABAQUS, a commercial finite element code. The result of KNR1/40 conical wheel is compared to those of the proposed wheels, all of which are arc wheel profile type.

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A study on the axial force and displacement characteristics of turnout on a bridge (분기기와 교량의 상호작용 특성에 관한 연구)

  • Yang, Shin-Chu;Kim, In-Jae;Kim, Eun
    • Proceedings of the KSR Conference
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    • pp.1306-1311
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    • 2006
  • Most of design parameters of Railway Structures are determined by the serviceability requirements, rather than the structural safety requirements. The serviceability requirements come from Ensuring of Running Safety and Ride Comfort of Train, Reduction of Track Maintenance Work Track-Bridge Interaction should be considered in the design of railway structures. In this study, a numerical method which precisely evaluate an axial force in rail and a rail expansion and contraction when turnout exist in succession on a CWR on a ballasted or on a ballastless track of bridge is developed. From the parameter studies using the developed method, additional stress of stock rail almost 25% is generated due to stock and lead rail interaction, even embankment not bridge. In case of ballasted track, additional stress of stock rail on bridge is very greater than on embankment, and therefore require detailed review in bridge design with turnout. Stresses of turnout rails on bridge are very sensitive according to the installed positions. In case of ballastless track, Stresses of turnout rails are similar as those of normal track

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