Study of Rail Structure: Risk Analysis and Failure Mode

moot of discipline Structure hazard abstract and mishap ModeStudy of raceway StructureRisk synopsis and stroke Mode AvoidanceIn this case study, a shortened overview of vilifyway structure is discussed. Defects relate to racetrack failure ar considered requirement to frame extinct the correct bread and unlesster st straygy. As it is closely associated with resort of passenger and cargo transportation, hence it retains high endangerment in basis of serviceman lives and be of resources. There will always be nearly run a find associated with collisions and de civilisements but it poop be reduced by eradication of the reconcile causes. Exposure and amendment of quetch blurs are major(ip) issues for all discipline companies round the world.There are challenges to the infrastructure maintenance individuals to perform hard-hitting revue and cost effective rectification decisions. If addressed properly these potentiometer reduce likely risk of raceway b reaks and de groomments.Risk assessment and Failure panache avoidance has become a vital constraint for the organisations to settle a cost effective and improved solution that could meet the pecuniary constraints regarding inspection, renewal and re determinement of leaderships and wheels. This study aims to reduce costs and risks think to discipline operation by effective approaches. The issues and challenges think to vilify maintenance are forthlined. The maintenance strategy followed by most vilifyway companies is alike defined.Large kvetchways infrastructures are the prime manner of transportation in some(prenominal) countries. Improved and give out safety measurements are continuously presented but steady could non be considered as incidents proof. There will always be some risk related with de civilizements and other occurrences such as major disruption to services, which can furthered be minimised by detailed examination of the root causes. Some of the caus es require improvement in skill and efficiency, for example valet error, and some whitethorn be improved by optimization of inspection regularity. Therefore, a appropriate thorough study of the defects which develop both on the rolling stock and rail infrastructure is vital to frame out the correct maintenance approach. European Union spends around 2 cardinal ein truth year for maintenance and repairing of broken plain (European missionary station Cordis, 2017). It is mum that the consequential cost cod to derailment decreases with rise in inspection, lubrication and contriteness charges. Risk in railways could be expressed in terms of cost, loss of human lives, infrastructure unavailability, traffic delay and environmental impact which may be caused due to derailment of a train carrying hazardous stuff.In this report, varied kinds of rail defects and maintenance procedures followed aredescribed. Different risk assessment and failure mode avoidance methods and tools have been discussed briefly in this report. Some of the issues and challenges related to railmaintenance are withal addressed with an aim to reduce the radical cost and risks associated with rail operations. aims are longitudinal brace members that harbor wheel loads and distribute these loads over the sleepers or supports, point the train wheels evenly and continuously. It is one of the most classical components of the track structure. usually a flat bottom railis used in customary railway track, which can be separated into 3 parts rail head, rail weband rail foot. Many standards are used for rail profiles. (Kumar, 2007) go through 1 shows the 2 third estate rail profiles. anatomy 1 Flat bottom and Bullhead rail profilesThe rails must consume sufficient stiffness so that they can act as beams and exaltation the concentrated wheel loads to the spaced sleeper supports without excessive deviation between supports. (Ernest and John, 1994)Due to economic pressure, there is a worl d-wide trend to extend axle loads, traffic tightfistednessand speed to reduce the operating cost and append the efficiency of railways. Axle loadsaround the world have increase in general from 22.5 to 32.5 Tonnes in last ten years (Allen, 1999). This has led to increased rate of defect formation in rails. Some of the common defects are described in the following sections.4.1. ShellingShelling is a defect caused by loss of material initiated by sub progress fatigue. Shelling normally takes place at the gauge corner of high rails in curves. An elliptical shell like jibe propagates in the subsurface gibe to the rail surface. When these cracks emerge on the surface, they cause the metal to come out from the crack area. It is primarily eliminated by grinding. (Kumar, 2007) suppose 2 Shelling caused by brainiac Checks4.2. Head ChecksIn the crown area, the contact stresses are generally low as it has greater profile radius in similitude to the gauge side of rail. However, high conta ct stresses are produced on the high rails gauge corner, which usually has curve radius from 1000 to 1500 m. Headchecks are known to occur in tighter ((IHHA, 2001).If head checks are not controlled, they can cause a rail break. Grinding is the most common practice to remove head checks. blunt head checks need rail section replacement.4.3. SquatsUnlike shelling, gobs appear in crown area of refined rail sections. They are surfaceinitiated defects formed by RCF. A squat is formed by two cracks, a leading crack and atrailing crack. Both these cracks propagate in opposite direction. These defects could be bared by grinding. (Kumar, 2007)4.4. SpallingSpalling occurs, when the surface initiated crack development path is intersected by other standardized shallow cracks on the rail head area, a shallow act of rail material falls out. Spalling is more common in cold climates as rail stiffness increases. rule 3 Gauge coigne Spalling in rails 4.5. Tache OvaleTache Ovale is a subsurface defect formed around 10-15 mm below the rail head surface (see Figure 4). This is caused by hydrogen accumulation during manufacturing of rail or when poor welding is through in rails. Thermal and residual stresses in like manner contribute to form this defect.Figure 4 Tache Ovale 4.6. Plastic Flow and Tongue LippingPlastic flow occurs in rail head area, the depth of which may be up to 15 mm. Plastic flowoccurs on the field side of the low rail due to overloading. Tongue lipping is also a form of plastic deformation, but it is initiated by surface cracks. These cracks partially separate a layer of material from the bulk of rail. (IHHA, 2001)4.7. thunderbolt Hole Crack xerox holes appear in the rail web often starting from the fastening point of fishplates. scarcelythese become weak points to resist crack initiation. These cracks have a really high potential to cause rail break and needs pressing replacement.4.8. Longitudinal Vertical CrackThis is a manufacturing defect, which u sually appears in the rail web and may extend in railhead also. If this crack is intersected by some other crack, it may lead to an early railfracture. Odds of sudden fracture due to this become predominant in cold climate.Figure 5 Longitudinal vertical crack 4.9. crosswise CrackTransverse crack is mostly developed in the cross-sectional area of defective weld joints. Awelding defect may be due to variation in weld material or rail manufacturing defect. Figure 6 shows a Transverse crack develops from the magnetic core of the rail head or the rail foot. Use of clean steel and deeper hardening of rail head may avoid its formation. (Kumar, 2007)Figure 6 Transverse crack 4.10. BucklingLateral buckling in rails is a very common defect in which the rail bulges out on its any sidedue to expansion. As the temperature rises, longitudinal expansion in rail takes place.4.11. CorrugationCorrugation is a rail flaw consisting of the wave-like wearing of the rail tread visualize aspeaks and v alleys, in other words, it is a degreeic irregularity of the rail surface (IHHA, 2001),see Figure 7.Figure 7 Corrugation in railsRail corrugations are the result of a damage mechanism, such as wear etc. Rail corrugations do not pose risk of immediate derailment, but they may be responsible for loosening of rail fastenings, ballast deterioration, increase in noise and vibration level leading to passenger discomfort, etc.Two main types of corrugations which generally occur in rails areShort pitch corrugationsLong pitch corrugationTables below show the percentage and type of defect detection by different rail infrastructurecompanies. railwayFirstSecondThird poopRail track (1999/2000)Squats 21.7%Vertical/transverse 20.1%Horizontal/longitudinal 12.5%Bolt holes 9.6%SNCF (1999)Squats 23.4%Internal fatigue 11.5%Shells 8.4%Thermite welds 4.7%HSPC (1999)Thermite welds 31.5%Wheel fire 17.2%Horizontal cleave webs 13.3%Bolt holes 11.3%NS (1997)Insulated Joints 59.4%Transverse defects 18%Therm ite welds 15%Fatigue Failure5.2%DB (1996)Thermite welds 29%Sudden fracture 18%Fatigue Failure 16% galvanising bonds4.0 %Banverket(1998)Transverse fracture 55.1%Welded joint 32.7%Horizontal defect 6.1%Vertical split2.0%HH1 (1999)Vertical split heads 34.7%Thermite welds 20.3%Detail fractures 13.1%Bolt holes 12.2%HH2 (1999)Transverse defects 23.6%Thermite welds 15.5%Wheel burns 13.2%Shells 9.6%Table 1 Causes of defective rails (Source Kumar, 2007)Rail breaks and derailments can cost the rail players in terms of loss of revenue, property, environmental damage or even loss of life. Estimation of these costs and analysis of risks are all-important(a) in deciding effective maintenance strategies. In simple terms, risk can be defined as the chance or fortune of loss, damage or injury. (Reddy, 2004)5.1. Failure Mode and Effects Analysis (FMEA)FMEA is a step-by-step procedure for systematic evaluation of the severity of potential failure modes in a system. This process was originally develo ped in the 1960s, to go bad the safety of aircrafts, but has been since applied to several other fields, including nuclear advocator plants and the military. (Villemeur, 1992-A)Figure 8 Schematic representation of the FMEA. (Source Villemeur, 1992-A).5.2. Risk Priority name (RPN)Risk priority number (RPN) is a methodology for analysing the risk associated with potentialproblems identified during (FMEA) (for details refer Reliasoft, 2005).Assigning RPN requires the analysis team to rate each potential problem per three rating scalesSeverity occurrentDetectionAfter the ratings, have been assigned the RPN for each issue is metrical as mentioned below,RPN = Severity x Occurrence x DetectionRail maintenance issues can be broadly classified into watchfulness issuesIssues related to rail wear, RCF and rail weldingRectification and replacement issues6.1. Rail Inspection IssuesThe effectiveness of rail inspection depends on the efficiency and accuracy of the inspectingequipment. It also depends on the skill and experience of inspectors. Error in inspection is an important issue and its reduction is a big challenge. This mainly depends on the technological limitations of the inspection equipment and the skill level of the rail inspectors.Figure 9 Rail inspection issues (Source Kumar, 2007)6.2. Issues related to Rail Wear, RCF and Rail WeldingFigure 11 outlines the rail maintenance issues. The following sections briefly describe someof these issues.Figure 10 Rail maintenance issues (Source Kumar, 2007)6.2.1. Rail Wear IssuesWear occurs due to interaction of rail and wheel. It includes mild and severe wear. Mild wear takes place slowly but severe wear is often much faster. Severe wear is predominant in curves and occurs dry conditions. Lubrication techniques are used to prevent such wears.Four commonly used techniques which are followed for rail-wheel lubrication are take in of rail lubricatorsWheel flange lubricatorsWayside lubricatorsOn board lubricators6.2.2. rin glet Contact Fatigue (RCF) IssuesIn the late 1990s RCF accounted for nearly 60% of defects found by East Japan Railways, while in France (SNCF) and UK (Railtrack) the attends were about 25% and 15%,respectively. RCF is a major future concern as business demands for higher speed higher axle loads, higher traffic density and higher tractive forces increase (see Cannon et al, 2003).Rail grinding removes surface metal from the rail head. It is done mainly with intensions to control RCF defects and rail wear. Rail grinding became increasingly recognized for controlling RCF defects from 1980 onwards, prior to that it was mainly pore on corrugation removal.6.2.3. Rail Welding IssuesSmall imperfection in welds can cause cracks to initiate. A defect free weld requires consummateworkforce, fail weld material along with improved welding techniques and equipment.6.3. Other Issues touch on Rail Wear, RCF and Rail WeldingRisk and cost are analysed by rail infrastructure operators in mainten ance decisions. It covers rail lubrication, rail grinding and rail weld.Other important issues areRail materialRail traffic density and axle loadTrack geometryIn Conclusion, first a brief overview of rail structure is discussed. Then, diverse range of rail defects and abjection processes have been studied. From the literature analyses done, it is interpreted that there is a need for better ways to monitor and predict rail defects over a period based on operational conditions and maintenance tactics. A good experience of risk along with an idea of the methods used for risk analysis is also required. Hence, before improvement of any model or any falsifiable relationship associated with risk and failure, there should first be a familiarity with risk management tools and failure mode avoidance. This study focuses on some such tools.Also, the issues and challenges related to rail maintenance are discoursed. The aim is to reduce risks related to rail operation that leads to failure mod e, by effective decisions associated to rail inspection, grinding, rectifications lubrications, and rail replacements. Some of the challenges in this area include development of cost effective maintenance decisions, reliability and availability of logistics support, which include availability of capable equipment, skilled personnel and availability of rail track.8.1. ReferencesAllen, R., (1999) Finding best practice at the wheel/rail interface, external RailwayJournal, Volume 6, pp. 48-50.European Commission Cordis (2017) AutoScan Rail inspection. Available from http//cordis.europa.eu/project/rcn/203338_en.hypertext markup language sighted February 2017Cannon, D. F., Edel, K.O., Grassie, S. L. and Sawley, K. (2003) Rail defects an overview,Fatigue discontinue of Engineering Materials Structures, Volume 26, October 2003, pp.865-886.Ernest, T. S. and John, M. W. (1994) Track Geometry and Substructure Management,Thomas Telfold.IHHA (2001) Guidelines to best practices for dangerou s haul railway operations wheel and railinterface issues, International Heavy Haul Association, May 2001, Virginia, USA.KUMAR, S. (2007). Study of Rail Breaks Associated Risks and Maintenance Strategies. Lulea Railway Research Center (JVTC)MIL-STD-1629A, (1980) Military Standard Procedures for Performing a Failure Mode,Effects and Criticality Analysis, Department of Defence, USA. Available from http//www.uscg.mil/hq/g-m/risk/e-guidelines/RBDM/html/vol4/Volume4/Toolspec_Rec/FMEA/MIL-STD-1629A.pdf sighted February 2017Reddy, V. (2004) Modelling and Analysis of Rail Grinding Lubrication Strategies forControlling whorl Contact Fatigue (RCF) and Rail Wear, Master Thesis, QueenslandUniversity of Technology, Brisbane, Australia.Reliasoft (2005) Examining risk priority be in FEMA, Reliability Edge, volume 4,issue1. Available from http//www.reliasoft.com/newsletter/2q2003/rpns.htm sighted February 2017VILLEMEUR, Alain (1992-A, 1992-B). Reliability, Availability, Maintainability and guard Assessment, A Vol. 1 Methods and Technique. B Vol.2 Assessment, Hardware, Software and Human Factors John Wiley Sons.8.2. FiguresFigure 1 https//upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Rail_profile.svg/800px-Rail_profile.svg.png?1487817217791Figure 2 http//www.ndt.net/ name/v07n06/thomas/fig3.jpgFigure 3 http//www.railwayexpertwitness.com/images/inspect9-300.jpgFigure 4 https//www.researchgate.net/publication/229632336/figure/fig8/ASemailprotected/Figure-1-Tache-ovale-or-kidney-rail-failure.pngFigure 5 http//www.ndt.net/article/0698/schub/fig1.gifFigure 6 http//mikes.railhistory.railfan.net/imfile/09192.jpgFigure 7 http//railmeasurement.com/wp-content/uploads/2015/04/corrugation-track1.jpgFigure 8VILLEMEUR, Alain (1992-A, 1992-B). Reliability, Availability, Maintainability and Safety Assessment, A Vol. 1 Methods and Technique. B Vol.2 Assessment, Hardware, Software and Human Factors John Wiley Sons.Figure 9 and 10KUMAR, S. (2007). Study of Rail Breaks Associated Risks a nd Maintenance Strategies. Lulea Railway Research Center (JVTC)