Detailed site modelling the model has been applied to predict the occurrence of rcf at a number of sites. Gage corner cracking gcc of rail and wheel from rolling contact. Influence of leaf, humidity and applied lubrication on. Frictional heating at the interface causes the temperature of the contacting rail surface and wheel surface to rise. They include a hub, wherein an axle is inserted, a rim that contacts the rail, and a web that unites the two parts.
Wear of the surface of a rail can be beneficial in removing small cracks, and by slowing the effective crack growth rate for larger cracks. Metro wheels are small in diameter, some have rubber layers between. According to the union pacific railroad wheel fracture database, 65% of railroad wheel failures are caused by shattered rims, a form of subsurface initiated rollingcontact fatigue rcf. The rising of temperature on the wheel rail surface may soften the material, and affect the strength of the material 5. But wheel rcf, if left unattended, can have catastrophic consequences. Wear at the wheelrail interface when sanding is used to. Fine surface cracks are often seen on wheels, but if they do not propagate below the nearsurface region, they do not have a significant influence on the costs and risks associated with wheel tread damage. This thesis concerns the influence of surface roughness of wheel rail surfaces on runningin behaviour, wear, friction and resultant surface damage. Check for sidewall rollover if you see any scuffing or wear past the edge of the tread pattern, your tires are rolling over too far. Fatigue of rails and wheels center for railway research. Rails and wheels are the foundation for every rail operators success. The outer circumferential surface of the rim, which contacts the rail, is tread, and the projected part is flange. Proposed procedure for determining wheel and wheelset dimensions.
Plane strain elements with reduced integration cpe4r are used both for the wheel and for the rail mesh. The wear and surface appearance of wheel damage on this fleet has been. Rolling contact fatigue rcf describes the process in which cracks grow as a result of the contact stresses between a rolling wheel and the rail. The influence of wheelrail contact conditions on the. This suggests a need for methods that can effectively predict the occurrence of rcf cracks. The growth rate of rail surface and subsurface fatigue cracks as shown in figures 1 and 2 is influenced by the level of contact stress between the wheel and the rail refer to section 6. A twodimensional crack model is proposed which calculates the crack driving force using the configurational force concept. Cracks start at the rail surface and develop into the rail at an angle of about 20 to the. We show everything you need to know to build this basement yourself.
Owing to surface cracks andor unacceptable geometry, wheels are reprofiled. Initiated cracks are in this case worn off and will not be able to propagate deep beneath the surface of the rail or wheel. The tribofatigue damage transition and mapping for wheel. There is also less plastic flow and wear on hard rails, so the profile changes more. Micro cracks develop at the most stressed portion of the rail surface.
Effect of wear on surface crack propagation in railwheel wet. Four curves were studied with radius between 303 and 616m. As well as wear by abrasion, the discs were subject to a rapid fatigue process and large chunks of material fractured from the surface. For resting tired feet, a foot rail about 79 inches above the floor adds a professional touch to a basement bar. A thin streaks of martensite on the rail surface because of high creep rates from. A tool to estimate the wheelrail contact and temperature. Fatigue cracks initiate on the wheel specimen surface. Wear contact mechanics and wear of rail wheel systems. Surface crack measurement accurate measurement for conditionbased maintenance of rails and wheels rails and wheels are the foundation for every rail operators success. In each case the predictions have been validated through comparison with the locations and surface lengths of rcf cracks in each site. With our highly motivated team of over 200 engineers and experienced specialists we have offered services for manufacturers and operators of rail systems since 1996. Two frequent rail surface defects caused by the wheel rail contact are rolling contact fatigue cracks in the gauge corner socalled head check and squats.
The result of fatigue wear is severe plastic deformation. A penalty contact formulation is used for both contact surfaces between the wheel and the rail and between the crack faces. This can be minimized by correct alignment of the wheels, flange lubrication, material of wheel and rail being similar and equipment in proper mechanical condition. Our comprehensive portfolio includes measuring systems for digitalized condition monitoring of rolling stock and rail infrastructures, and inspection systems for rail networks. On the surface scratch and thermal fatigue damage of wheel. Wheel and rail inspections are carried out as part of the regular maintenance procedure. Previous studies of wheel wear and rcf crack initiation and. A tool to estimate the wheel rail contact and temperature rising under dry, wet and oily conditions abstract. Smart measurement digital services siemens mobility. Frederick 11 discussed the effect of train speed and wheelrail forces as a result of surface roughness.
Proposed procedure for determining wheel and wheelset. A finite element model to simulate the physical mechanisms of wear and crack initiation in wheel rail contact. Damage mechanisms such as surface cracks and wear on a rail can reduce the service life of a railway track. Effect of head wear on rail underhead radius stresses and. Figure 1 shows the cycle of crack growth into the rail surface. Wear of wheels occurs on the wheel tread and flange. Blend at relatively low speed and be sure to blend only a small amount of cement that can be placed within working time. These studies have indicated that shelling is essentially a fatigue failure.
The previous section focused on rcf crack initiation in wheels. The ability to measure rail profile, wear, surface cracks, and corrugation is enabling us to take a more scientific approach to rail grinding, said gordon bachinsky, president of advanced rail management corp. The outer circumferential surface of the rim, which contacts the rail. The numerical applicability of the configurational force concept for surface shear cracks under cyclic contact loading is discussed and compared to the jintegral concept. Rolling contact fatigue rcf defects such as squats or surface shellings. Effect of shoe braking on wear and fatigue damage of. Simple search advanced search research publications advanced search student theses statistics. Proactively manage rail maintenance to reduce rail wear section loss control gauge face wear control rolling contact fatigue rcf. Nrc publications archive archives des publications du cnrc. Alternatively, look for barstools with footrests that are comfortable to use. Eckart uhlmann, pavlo lypovka, leif hochschild, nikolas. Contaminants, which refer to foreign substances applied both intentionally and unintentionally the wheel to rail interface, can make wheel rail adhesion either too high or too low and to difficult predict. The role of arrest shoe braking on final damage appears not relevant. Rail wheel interaction indian railways institute of.
In the past, the rate of rail wear was fast enough to wear away surface cracks. Rails must be replaced prematurely when they wear faster than rcf. Surface crack measurement digital asset management. Mechanism analysis of spalling defect on rail surface under. At a high wear rate, rcf does not have the opportunity to develop further. Of friction more slide sqeal and rail corrugation proper management can. Ratcheting, wear and formation of surface cracks occur in dry wheelrail contact. Recent studies of the rail wheel interface have shown that wear and rolling contact fatigue rcf are competitive phenomena. Both crack initiation and propagation are impacted by the rate at which material is worn from the surface. By now the focus of rail inspection was moved to surface defects induced by material fatigue. Press firmly the paste into place, maintaining the same amount of pressure until the cement begins to harden and the leak is stopped. Wheel rail adhesion wear investigation using a quarter scalelaboratory testing facility article pdf available in proceedings of the ieee january 1996 with 116 reads how we measure reads.
High loads and traffic volumes lead to wear, surface cracking, rolling contact fatigue rcf, radial cracks. Rolling contact fatigue, rcf, rail gauge corner cracking, wheel tread cracking. A solid wheel of a railway vehicle hereinafter wheel consists of three parts, as shown in fig. The crack orientation is assumed to be perpendicular to the rail surface in the middle of the rail. Rail grinding and its impact on the wear of wheels and rails. The crack tends to propagate upward and leads to spalling defect when. Visit our amazon store to find tools and products that jeff uses s. Repeated, alternating mechanical stresses lead to the formation and propagation of cracks under the stressed surface, which is thus destroyed. The sidewall rubber compound is different than the tread rubber and is not designed.
The interaction between wear and rolling contact fatigue in wet contact was investigated by means of experiments on a twodisk test bench. These cracks are most often found to originate in the region of maximum shear stress below the surface as seen in fig. A model to predict and understand rolling contact fatigue. Surface cracks arising during rolling sliding contact of a wheel and a rail are investigated. Competition between wear and rolling contact fatigue at. Conquering rolling contact fatigue and gage corner cracking. Start applying the hydraulic cement at the top of the crack making your way down. Both wheels and rails wear and change in some dimensions with use. Refining approaches to corrective and preventive rail grinding.
Internal defects, surface conditions and maintenance techniques by gordon bachinsky 1. Wear, by removing the material from the contact surface, tends to limit the propagation of cracks formed by cyclic contact stresses. A simple abrasive wear model has been developed to predict wear of rail material caused by sand in the wheel rail. Studies were made of wheels that shelled in service after being subjected to the usual ontread braking as well as a wheel equipped with disctype brakes. Effect of head wear on rail underhead radius stresses and fracture under high axle load conditions. The causes for reprofiling or grinding are, in most cases, related to the following. Brake marks from cargo cars very often appear on the outer diameter of the wheels.
Influence of rail grinding process parameters on rail surface roughness and surface layer hardness. Fatigue wear prevention must be a consideration in planning and design phases. Abstracta novel test method has been used to study how applied and natural lubrication leaf and humidity influences the coefficient of friction in the wheel rail. High loads and traffic volumes lead to wear, surface cracking, rolling contact fatigue. The purpose of this investigation was to study the development of these two damage mechanisms on new and 3yearold rails in a commuter railway track over a period of 2 years. Simulation and measurement of wheel on rail fatigue and wear. Diy how to renovate an unfinished basement a to z youtube. Crack growth tendency of surface shear cracks in rolling. The trains are heavy, hence the wear typically overrolled material, high flanges, holes and flat spots on the wheels is high. Such wheels may be identified by presence of flats even within acceptable limits and severe. As the wheel rail contact is an open system, the adhesion between the wheel and rail is inevitably affected by contaminants.
Every effort should be made to avoid the abnormal loss of tread metal caused by thermal cracking and shelling. Railroads doing preventive grinding which eliminates rail surface cracks are able to best utilize proper lubrication strategies to reduce wear and the traction stresses at the wheel rail contact surface and to increase the number of cycles before surface cracks develop and the profile plastically deforms. Damage mechanisms such as surface cracks, plastic deformation and wear, see for example kalousek et al. The rail discs are scored by sand particles that embed and stick in the softer wheel disc. Surface cracks propagation occurs in subsequent wet contact.
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