• Title, Summary, Keyword: Rail stress

검색결과 251건 처리시간 0.046초

Stress Analysis in the Elastic-Plastic Analysis of Railway Wheels

  • Ashofteh, Roya Sadat;Mohammadnia, Ali
    • International Journal of Railway
    • /
    • v.7 no.1
    • /
    • pp.1-7
    • /
    • 2014
  • Fatigue and wear in wheels is often due to the forces and loading. These certainly have fundamental effects on reducing the wheel life and increasing the costs related to repairing and maintenance. Modeling and stress analysis of a wheel sample existing in the Iranian fleet have been performed in its contact with U33 and UIC60 rails. The results have been reviewed and analyzed in elastic and elastic-plastic phase and under static (railcar weight) and quasi static loads. Moreover, effects of wheel diameter, axle load, wheel material, rail type are analyzed.

Worn Wheel/Rail Contact Simulation and Cultivated Shear Stresses

  • Noori, Ziaedin;Shahravi, Majid;Rezvani, Mohammad Ali
    • 한국철도학회논문집
    • /
    • v.16 no.2
    • /
    • pp.93-98
    • /
    • 2013
  • Railway system is today the most efficient way for transportation in many cases in several forms of application. Yet, wear phenomenon, profile evolution, fatigue, fracture, derailment are the major worries (financial and safety) in this system which force significant direct and indirect maintenance costs. To improve the cyclic maintenance procedures and the safety issues, it can be very satisfactory to be informed of the state of wheel/rail interaction with mileage. In present paper, an investigation of the behavior of the shear stresses by logged distance is approached, by implementing the field measurement procedure, in order to determine the real conduct of the most important cause of defects in wheel/rail contact, shear stress. The results coming from a simulation procedure indicate that the amounts of shear stresses are still in high-magnitudes when the wheel and rail are completely worn; even though in simulation based on the laboratory measurements of profile evolutions, the stresses become significantly reduced by logged distance.

전자력 발사기의 최적 구조 설계 (Optimal Structural Design for the Electro-magnectic Launcher)

  • 이영신;안충호
    • 전산구조공학
    • /
    • v.9 no.2
    • /
    • pp.143-151
    • /
    • 1996
  • 구조 및 전기적 제약조건을 고려한 전자력 발사기의 최적설계에 대해 연구하였다. 펄스형 대전류가 흐르는 발사기의 단면적이 최소화되었으며 각 요소(레일, 측면벽, 세라믹 및 강철)의 허용응력과 예하중을 고려하였다. 전기적 제약조건은 발사기의 성능을 저하시키는 와전류 효과를 방지하기 위한 세라믹의 두께로 정하였다. 90mm발사기의 설계에서 응력해석과 최적화는 ANSYS코드를 사용하여 수행되었다. 예하중을 받는 최적설계에서는 예하중을 받지 않는 최적설계보다 53%의 단면적이 감소되었다. 레일의 원호각이 45.deg.일때 발사기의 성능이 가장 양호하다. 레일의 원호각이 45.deg.일때 Fahrenthold 연구결과와 비교하여 9%의 변형량 감소와 10.4%의 변형량 감소를 얻었고, 예하중도 186Mpa에서 59.8Mpa로 감소되었다. 연구결과는 설계 요구조건을 충분히 만족시켜 주고 있음을 보여 주었다.

  • PDF

현장측정을 통한 노후레일의 휨 피로수명 평가 (Bending Fatigue Life Assessment of Aged CWR using the Field Test)

  • 박용걸;성덕룡;박홍기;공선용
    • 한국철도학회논문집
    • /
    • v.11 no.3
    • /
    • pp.317-325
    • /
    • 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.

차륜/래일 접촉에 의한 차륜의 잔류응력 평가 (Evaluation of Residual Stress of railway wheel)

  • 서정원;구병춘;정흥채
    • 한국철도학회:학술대회논문집
    • /
    • /
    • pp.668-673
    • /
    • 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.

  • PDF

철도차량 차륜의 잔류응력 평가 (Evaluation of Residual Stress of railway wheel)

  • 서정원;구병춘;이동형;정흥채
    • 한국철도학회:학술대회논문집
    • /
    • /
    • pp.208-213
    • /
    • 2002
  • Railway wheel and axle are 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 evaluation of wheelset strength and safety has been desired. 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 and thermal stress from heat induced in braking. The objective of this paper is to estimate the variation and magnitude of the residual stress of railway wheel.

  • PDF

지오그리드로 보강된 철도노반의 한계속도에 관한 연구 (Critical Speed Analysis of Geogrid-Reinforced Rail Roadbed)

  • 신은철;이규진;오영인
    • 한국철도학회:학술대회논문집
    • /
    • /
    • pp.534-539
    • /
    • 2001
  • This paper presents the critical speed analysis of geogrid-reinforced rail roadbeds on soft soil. A rail roadbed on soft ground must be designed to avoid intolerable stress in the underlying soil and to give sufficient support for the rail system. At high speeds, the deformation of rail systems will gain dynamic amplification, and reach excessive values as a certain speed, here termed critical speed is approached. The elastic Winkler foundation model was used to predict the critical speed of geogrid-reinforced rail roadbeds on soft soil and the model properties were determined by the in-situ cyclic plate load test. Based on the parametric study of elastic beam on Winkler foundation model, the critical speed increase with the increase of the flexural risidity of subgrade EI and the stiffness coefficient of Winkler foundation k. From the in-situ cyclic load tests and analysis of elastic beam on Winkler foundation model, the critical speed increase with increase in number of reinforced layer and non-dimensional value for depth of first geogrid layers and the thickness of reinforced rail roadbed u/d.

  • PDF

A Study on Fatigue Crack Propagation of Rail Steel under Constant and Mixed Mode Variable Amplitude Loadings

  • Kim, Chul-Su;Chung, Kwang-Woo
    • International Journal of Railway
    • /
    • v.5 no.2
    • /
    • pp.71-76
    • /
    • 2012
  • Recently, axle load, operating speed and traffic density on railroads have had a tendency to increase and thereby cause additional pressure applied on used track. These operating conditions frequently result in service failure due to wear caused by wheel-rail contact and fatigue damage under cyclic loading. Among rail defects, the transverse crack, which has been the most dangerous type of fatigue damages, is developed from the subsurface crack near the rail running face and grows perpendicular to the rail surface. Therefore, it is necessary to investigate systematically the growth behavior of transverse crack for rail steel under mixed mode. In this study, the fatigue crack growth behavior of the transverse crack in rail steel was experimentally investigated under mixed-mode variable amplitude loadings.

전기철도의 공용접지 시스템에 대한 안정성 평가에 관한 연구 (Safely Evaluation on Common Grounding System for Electric Railway)

  • 송진호;황유모
    • 대한전기학회논문지:전기기기및에너지변환시스템부문B
    • /
    • v.51 no.6
    • /
    • pp.298-306
    • /
    • 2002
  • We performed an safety evaluation on constructing of a common grounding system for electrical railway in view of its efficacy and technical fit. In order to compare the conventional grounding method, which has been individually conducted, with the common grounding with all ground wires connected in common to the counterpoise buried below the surface of the earth in parallel with rail, we set up scenarios with several cases of fault and load conditions in Chungbuk railway sections with the common grounding system. Based on models for railway conductors including the grounded system, line Parameters of railway power system are computed. The circuit model for power system with up and down lines, auto-transformers and railway substations is used to compute impedances of counterpoise and substation ground net. For each scenario with faults and operation conditions of railway, the induced potentials on signal and communication lines are also computed. It is shown that the common grounding for Chungbuk railway is superior experimentally to the conventional method in three respects: (1) the lower rail potentials during operation of railway in line, (2) the lower rail potentials for short-circuit faults between catenary and rail, and (3) the lower stress voltages on signal and communication lines for short-circuit or ground faults. The analysis results confirm that the grounding system for electric railway is required to be built by the common grounding and be evaluated on its safety in design.

Continuous deformation measurement for track based on distributed optical fiber sensor

  • He, Jianping;Li, Peigang;Zhang, Shihai
    • Structural Monitoring and Maintenance
    • /
    • v.7 no.1
    • /
    • pp.1-12
    • /
    • 2020
  • Railway tracks are the direct supporting structures of the trains, which are vulnerable to produce large deformation under the temperature stress or subgrade settlement. The health status of track is critical, and the track should be routinely monitored to improve safety, lower the risk of excess deformation and provide reliable maintenance strategy. In this paper, the distributed optical fiber sensor was proposed to monitor the continuous deformation of the track. In order to validate the feasibility of the monitoring method, two deformation monitoring tests on one steel rail model in laboratory and on one real railway tack in outdoor were conducted respectively. In the model test, the working conditions of simply supported beam and continuous beam in the rail model under several concentrated loads were set to simulate different stress conditions of the real rail, respectively. In order to evaluate the monitoring accuracy, one distributed optical fiber sensor and one fiber Bragg grating (FBG) sensor were installed on the lower surface of the rail model, the strain measured by FBG sensor and the strain calculated from FEA were taken as measurement references. The model test results show that the strain measured by distributed optical fiber sensor has a good agreement with those measured by FBG sensor and FEA. In the outdoor test, the real track suffered from displacement and temperature loads. The distributed optical fiber sensor installed on the rail can monitor the corresponding strain and temperature with a good accuracy.