| 1. |
- Bernal, Esteban, et al.
(författare)
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Friction-Slip Curves - The Pathway From Twin-Disc Tribo Measurements To Full-Scale Locomotive Multibody Simulations
- 2022
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Ingår i: PROCEEDINGS OF 2022 JOINT RAIL CONFERENCE (JRC2022). - : AMER SOC MECHANICAL ENGINEERS.
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Konferensbidrag (refereegranskat)abstract
- Locomotive multibody simulations are commonly used as a cost-effective tool to study, energy efficiency, wheel-rail wear, rolling contact fatigue, etc. The accuracy of the wheel-rail contact forces from multibody simulations depends on the correct modelling of the friction conditions. The friction coefficient is a function of the slip velocity, and it is influenced by several tribological parameters including, for example, material mechanical properties, environmental conditions and the presence of third body layers that vary spatially and temporally along the track. In most cases, generic friction-slip curves obtained from publications and public reports are used as inputs to the wheel-rail contact model in the locomotive simulations, as direct friction measurements using full-scale experimental set-ups are generally cost-prohibitive. A pathway to produce friction-slip curves from tribo-machine friction measurements is proposed in this paper. The pathway involves manufacturing discs from actual wheel and rail material samples to measure the traction coefficient at a spectrum of slip set points using a twin-disc tribo-machine. The tribo-machine results are scaled to be used in a locomotive multibody model that uses the modified Fastsim and a traction system co-simulation approach. Two friction curves for wet and dry conditions are processed and exemplified in a dynamic model.
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| 2. |
- Bernal, Esteban, et al.
(författare)
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Prediction of rail surface damage in locomotive traction operations using laboratory-field measured and calibrated data
- 2022
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Ingår i: Engineering Failure Analysis. - : Elsevier BV. - 1350-6307 .- 1873-1961. ; 135
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Tidskriftsartikel (refereegranskat)abstract
- Rail damage prediction is a complex task because it depends on numerous tribological parameters and the dynamic conditions produced by the vehicles operating at different speeds and configurations. Shakedown maps and Whole-Life-Rail-Model/T-Gamma have been used to predict rail damage, but they involve assumptions that may reduce their accuracy. This paper proposes a simulation modelling method to predict rail surface damage based on a locomotive digital twin, calibrated shakedown maps and friction measurements. The method improves the accuracy of rail damage predictions by including slip-dependent friction characteristics, co-simulation of locomotive traction mechatronic system and the mechanical properties of the wheel and rail materials measured through tensile tests. A set of operating conditions are simulated on a high-performance computing cluster, with stress results being post processed into calibrated shakedown heatmaps. The method clearly indicated the influences of the different operating conditions on rail damage for specific combinations of wheel-rail materials and vehicle-track configurations.
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| 3. |
- Krishna, Visakh V, et al.
(författare)
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Long freight trains and long-term rail surface damage : A systems perspective
- 2022
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Ingår i: Vehicle System Dynamics. - : Taylor & Francis Group. - 0042-3114 .- 1744-5159. ; , s. 1-24
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the authors present a detailed train-track interaction model of a long freight train operation to predict long-term rail surface damage. In addition to vehicles and track, intermediate maintenance actions in the form of cyclic grinding passes have also been modelled according to European standards to realistically represent the evolving wheel-rail interface. The influence of longitudinal train dynamics in the form of inter-vehicle interactions, traction, braking, gradients, etc is also included in this method to reflect their effect on damage evolution. The authors demonstrate that the novel ‘Train-track interaction’ formulation is more complete and therefore better suited to study long-term rail surface damage as opposed to existing ‘vehicle-track’ formulations since the former brings the system dynamics at play, significantly altering the wheel-rail interaction. A key highlight of this work is that the rail surface damage is expressed in the form of evolving rail profiles over a large tonnage passing and by depicting RCF-affected zones. This framework can be tuned into a digital twin to guide infrastructure managers regarding the condition of rail surface as a function of tonnage passage. This can in turn facilitate predictive maintenance of track depending on traffic and operation.
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| 4. |
- Krishna, Visakh V, et al.
(författare)
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Long freight trains & Long-term rail surface damage : Towards digital twins that enable predictive maintenance of track
- 2022
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Ingår i: Proceedings of the 13th World Congress on Railway Research (WCRR2022). - Birmingham, UK.
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Konferensbidrag (refereegranskat)abstract
- In this work, the authors present a detailed ’train-track’ interaction model of a long freight train operation topredict long-term rail surface damage. In addition to vehicles and track, intermediate maintenance actions inthe form of cyclic grinding passes have also been modelled according to EN standards to effectively representthe evolving wheel-rail interface. The influence of longitudinal train dynamics in the form of traction, braking,gradients, etc are also accounted in the method to reflect their effect on damage evolution. The two-stepmethodology consists of modules each modelling longitudinal train dynamics and long-term rail surface damagerespectively. The multi-disciplinary integrated numerical framework comprising of train, real operational casesand track attributes has been built based on principles of vehicle dynamics, tribology, and fatigue analysis. Themodel has been demonstrated for a heavy haul freight train operation on a 120 km long track section in thenorth of Sweden for which the results have been presented. Also, additional scenarios that can be expected ina real time operation with varying traction/braking, gradients etc have been considered. In the end, thisintegrated numerical framework comprising of 4 T’s namely train, track, tractive strategies, and trackmaintenance can be tuned into a digital twin to guide infrastructure managers regarding the condition of railassets as a function of tonnage passage. This can in turn facilitate predictive maintenance of track depending ontraffic and operation.
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| 5. |
- Mandal, Nirmal Kumar, et al.
(författare)
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FEA of mechanical behaviour of insulated rail joints due to vertical cyclic wheel loadings
- 2022
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Ingår i: Engineering Failure Analysis. - : Elsevier BV. - 1350-6307 .- 1873-1961. ; 133, s. 105966-
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Tidskriftsartikel (refereegranskat)abstract
- Insulated rail joints (IRJs), safety critical components of railway track, are used to locate trains and broken rails using electrical signalling systems. The bending rigidity of the rail at an IRJ is only 2/3(rds) as that of continuous rail. As a result, stress singularity problems occur at IRJs which therefore degrade faster compared to the continuous rail. Both railhead top surface and subsurface damage occurs and accelerates the initiation of cracks. Head hardened rails are used to overcome these problems. A thorough study addresses the damage pattern in the railhead sub-surface using a 3D finite element analysis (FEA) employing vertical wheel loadings considering three endpost materials: fibre glass (fb), nylon 66 (ny) and polytetrafluoroethylene (ptfe). A new damage parameter, the vertical residual stress component, is proposed to assess new patterns of railhead damage considering plastic deformation. To rank the influential stress related damage parameters, two other parameters are also considered, namely residual von-Mises and longitudinal stress components. Of these, the residual von-Mises stress component is more prominent with regard to the top surface and sub-surface damage, whereas the longitudinal stress component is responsible for top surface material damage. From these damage patterns, a progressive change in the hardness distribution of railhead material can evolve.
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| 6. |
- Mandal, Nirmal Kumar, et al.
(författare)
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On the railhead material damage of insulated rail joints : Is it by ratchetting or alternating plasticity?
- 2019
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Ingår i: International Journal of Fatigue. - : ELSEVIER SCI LTD. - 0142-1123 .- 1879-3452. ; 128
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Tidskriftsartikel (refereegranskat)abstract
- Railhead becomes severely stressed due to localised contact loadings. This is more critical in the vicinity of endposts of an insulated rail joint. Popular IRJ endpost materials are fibreglass (fb), polytetrafluoroethylene (ptfe) and nylon66 (ny). A 3D finite element analysis is carried out to study stress distributions in railhead material near the endposts. The progressive damage parameter, von Mises stress and other residual stress and strain plots indicate that plastic deformation and material degradation occur at sub-surface levels of the railhead material. Although fb and ptfe are better endpost materials than ny, ny displays superior performance over the other two.
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| 7. |
- Persson, Ingemar, et al.
(författare)
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Influence of non-dry condition creep curves in switch negotiation
- 2022
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Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; , s. 1-13
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Tidskriftsartikel (refereegranskat)abstract
- In the benchmark on switches and crossings, simulations have been carried out in different switch configurations and operational conditions, with a specified wheel/rail friction coefficient of (Formula presented.) considered as dry friction. This means that contamination or third-body layers are not taken into consideration, thus using a theoretical creep curve that is much steeper than the actual curves measured in real railways. In this paper, we perform a comparison between theoretical and measured creep curves and then estimate the impact on simulated creep forces when measured creep curves are used instead of theoretical ones.
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| 8. |
- Spiryagin, Maksym, et al.
(författare)
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Influence of AC system design on the realisation of tractive efforts by high adhesion locomotives
- 2017
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Ingår i: Vehicle System Dynamics. - : TAYLOR & FRANCIS LTD. - 0042-3114 .- 1744-5159. ; 55:8, s. 1241-1264
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Tidskriftsartikel (refereegranskat)abstract
- The main task for heavy haul railway operators is to reduce the cost of exported minerals and enhance the long-term viability of rail transport operations through increasing productivity by running longer and heavier trains. The common opinion is that this is achievable by means of implementation of high adhesion locomotives with advanced AC traction technologies. Modern AC high adhesion locomotives are very complex mechatronic systems and can be designed with two alternative traction topologies of either bogie or individual axle controls. This paper describes a modelling approach for these two types of AC traction systems with the application of an advanced co-simulation methodology, where an electrical system and a traction algorithm are modelled in Matlab/Simulink, and a mechanical system is modelled in a multibody software package. Although the paper concentrates on the analysis of the functioning for these two types of traction control systems, the choice of reference slip values also has an influence on the performance of both systems. All these design variations and issues have been simulated for various adhesion conditions at the wheel-rail interface and their influence on the high traction performance of a locomotive equipped with two three-axle bogies has been discussed.
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| 9. |
- Wu, Qing, et al.
(författare)
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Heavy haul rail/wheel wear and RCF assessments using 3D train models and a new wear map
- 2024
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Ingår i: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 538-539
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Tidskriftsartikel (refereegranskat)abstract
- Wear and Rolling Contact Fatigue (RCF) on wheels and rails are influenced by relative motions between the studied rail and wheel pair, and therefore influenced by train dynamics. Wear and RCF assessments using a train dynamics approach provide more accurate and comprehensive results comparing with conventional assessments that often do not consider train dynamics. In addition, considering material property differences, currently available rail wear maps are not able to accurately describe the wear performance of materials that have significantly different properties. This paper presented a method for rail/wheel wear and RCF assessments using 3D train dynamics models. The use of train models allows the consideration of coupler forces, traction, and brakes during the assessment. Wear assessments were conducted by using an in-house rail wear map model developed from the twin disc wear machine at the Centre for Railway Engineering (CRE). The new rail wear map was developed by using the AS 60 rail material (hardness 340 HB). The results indicated that the methods proposed in this paper could be used for rail/wheel wear and RCF assessments. Traction/braking forces and coupler lateral forces had evident influences on wear and RCF assessment. Different wear maps were also shown to have significant influences on the wear rate results.
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| 10. |
- Wu, Qing, et al.
(författare)
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RAIL/WHEEL WEAR AND RCF ASSESSMENTS USING 3D TRAIN MODELS AND A NEW WEAR MAP
- 2022
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Ingår i: CM 2022. - : International Conference on Contact Mechanics of Wheel / Rail Systems. ; , s. 217-222
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Konferensbidrag (refereegranskat)abstract
- Wear and Rolling Contact Fatigue (RCF) on wheels and rails are influenced by relative motions between the studied rail and wheel pair, and therefore influenced by train dynamics as well. Wear and RCF assessments by suing train dynamics provide more accurate and comprehensive results. In addition, considering material property differences, previous rail wear maps may not be able to accurately describe the wear performance of materials that have significantly different properties. This paper presents a method for rail/wheel wear and RCF assessments using 3D train dynamics models. The use of train models allows the consideration of coupler forces, traction, and brakes during the assessment. Wear assessments were conducted by using an in-house rail wear map model developed for a twin disc wear machine at the Centre for Railway Engineering (CRE). The new rail wear map was developed by using the AS 60 rail material. Results show that the older BS11 rail material wear rate regimes and transitions are evidently different to the wear behaviour measured for AS60 rail material.
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