| 1. |
- Gebretsadik, Elias Kassa, 1975-, et al.
(författare)
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Dynamic interaction between train and railway turnout : full-scale field test and validation of simulation models
- 2008
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Ingår i: Vehicle System Dynamics. - : Taylor & Francis Group. - 0042-3114 .- 1744-5159. ; 46:1, s. 521-534
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Tidskriftsartikel (refereegranskat)abstract
- Results from an extensive field test performed in a UIC60-760-1:15 turnout on Svealandsbanan in Sweden are reported. Lateral and vertical wheel-rail contact forces were measured by a wheelset instrumented with strain gauges on the wheel discs. The test train with axle load 25 tonnes passed through the turnout in the main and diverging routes and in the facing and trailingmoves. The influences of train speed and moving direction on the magnitude and the position of the maximum lateral contact force in the diverging route of the switch panel, and the influences of train speed, moving direction and route on the maximum vertical contact force in the crossing panel, are investigated. Measured contact forces are compared with calculated forces for a validation of two previously developed numerical models. The magnitude and position of the calculated maximum lateral contact forces are in good agreement with the corresponding measured values. Both measurements and numerical simulations show an increase in maximum lateral contact force with increasing train speed in both the facing and trailing moves. The facing move of the diverging route leads to the highest lateral contact forces in the switch panel. The maximum vertical contact force is not influenced significantly by whether the train is moving in the facing or trailing moves. However, the train route (main or diverging) has a large influence on the maximum vertical contact force at the crossing.
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| 2. |
- Gebretsadik, Elias Kassa, 1975-, et al.
(författare)
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Dynamic train-turnout interaction in an extended frequency range using a detailed model of track dynamics
- 2009
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Ingår i: Journal of Sound and Vibration. - : Elsevier BV. - 0022-460X .- 1095-8568. ; 320:4-5, s. 893-914
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Tidskriftsartikel (refereegranskat)abstract
- A time domain solution method for general three-dimensional dynamic interaction of train and turnout (switch and crossing) that accounts for excitation in an extended frequency range (up to several hundred Hz) is proposed. Based on a finite element (FE) model of a standard turnout design, a complex-valued modal superposition of track dynamics is applied using the first 500 eigenmodes of the turnout model. The three-dimensional model includes the distribution of structural flexibility along the turnout, such as bending and torsion of rails and sleepers, and the variations in rail cross-section and sleeper length. Convergence of simulation results is studied while using an increasing number of eigenmodes. It is shown that modes with eigenfrequencies up to at least 200 Hz have a significant influence on the magnitudes of the wheel-rail contact forces. Results from using a simplified track model with a commercial computer program for low-frequency vehicle dynamics are compared with the results from using the detailed FE model in conjunction with the proposed method.
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| 3. |
- Gebretsadik, Elias Kassa, 1975-, et al.
(författare)
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Geometry and stiffness optimisation for switches & crossings, and simulation of material degradation
- 2010
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Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - : Sage Publications. - 0954-4097 .- 2041-3017. ; 224, s. 279-292
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Tidskriftsartikel (refereegranskat)abstract
- A methodology for simulatingwear, rolling contact fatigue, and plastic deformation for a mixed traffic situation in switches and crossings (S&C) has been developed. The methodology includes simulation of dynamic vehicle-track interaction considering stochastic variations in input data, simulation of wheel-rail contacts accounting for non-linear material properties and plasticity, and simulation of wear and plastic deformation in the rail during the life of the S&C component. To find means of improving the switch panel design, the geometry of a designed track gauge variation in the switch panel has been represented in a parametric way. For traffic in the facing and trailing moves of the through route, an optimum solution was identified and then validated by evaluating a wide set of simulation cases (using different wheel profiles). The optimum design includes a 12 mm maximum gauge widening. Several crossing geometries were investigated to find an optimal geometric design for the crossing nose and wing rails. The MaKuDe design showed the best performance for moderately worn wheel profiles in both running directions (facing and trailing moves). In connection with reduced support stiffness (e. g. elastic rail pads), this crossing design is predicted to lead to a significant reduction of impact loads and consequently provide a high potential of life-cycle cost reduction.
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| 4. |
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| 5. |
- Gebretsadik, Elias Kassa, 1975-, et al.
(författare)
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Stochastic analysis of dynamic interaction between train and railway turnout
- 2008
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Ingår i: Vehicle System Dynamics. - : Taylor & Francis Group. - 0042-3114 .- 1744-5159. ; 46:5, s. 429-449
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Tidskriftsartikel (refereegranskat)abstract
- The performance of a railway turnout (switch and crossing) is influenced by a large number of input parameters of the complex train–turnout system. To reach a robust design that performs well for different traffic situations, random distributions (scatter) of these inputs need to be accounted for in the design process. Stochastic analysis methods are integrated with a simulation model of the dynamic interaction between train and turnout. For a given nominal layout of the turnout, using design of experiments methodology and a two-level fractional factorial screening design, four parameters (axle load, wheel–rail friction coefficient, and wheel and rail profiles) are identified to be the most significant. These parameters are further investigated using a three-level full factorial design and stochastic analysis. The random distributions of transverse wheel profile and set of transverse rail profiles along the switch panel are accounted for by the Karhunen–Loève expansion technique. The influence of the random distributions of the input parameters on the statistical outputs of wheel–rail contact forces, wear and rolling contact fatigue is assessed using Latin hypercube sampling to generate a number of stochastic load realizations.
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| 7. |
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| 8. |
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| 9. |
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| 10. |
- Nielsen, Jens, et al.
(författare)
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Optimisation of switches and crossings
- 2010
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Ingår i: INNOTRACK Concluding Technical Report. - Paris : International Union of Railways (UIC). ; , s. 161-167
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Bokkapitel (refereegranskat)
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