| 1. |
- Carlberger, Andreas, 1992, et al.
(författare)
-
Numerical prediction of rail corrugation growth on curves
- 2016
-
Ingår i: Proceedings of the 19h Nordic Seminar on Railway Technology, September 14 - 15, Luleå, Sweden (2016).
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Rail corrugation (periodic surface irregularities at distinct wavelengths) is a problem experienced by many railway networks worldwide. Corrugation induces a pronounced dynamic wheel‒rail contact loading that leads to increased generation of noise and in severe cases even damage to vehicle and track components. The large magnitude creep forces and sliding between wheel and rail make corrugation especially prone to develop on curved track. The current work summarizes the results from a Master Thesis project performed in collaboration between Chalmers, ÅF Industry, Bombardier Transportation and Stockholm Public Transport. A time-domain model for the prediction of long-term growth of rail roughness has been developed, see Figure 1. Dynamic vehicle‒track interaction in a broad frequency range (at least up to 300 Hz) is simulated using the commercial software SIMPACK. Wheelset structural flexibility is accounted for by using modal parameters calculated for a finite element model. Non-Hertzian and non-steady wheel‒rail contact and associated generation of wear are calculated in a post-processing step in the software Matlab. Archard’s law is applied to model the sliding wear. A large number of train passages is accounted for by recurrent updating of the rail surface irregularity based on the calculated wear depth. The proposed prediction model is applied to investigate a curve on the Stockholm metro network exposed to severe corrugation growth.
|
|
| 2. |
- Nielsen, Jens, 1963, et al.
(författare)
-
Switch panel design based on simulation of accumulated rail damage in a railway turnout
- 2015
-
Ingår i: Proceedings of the 10th International International Conference on Contact Mechanics and Wear of Rail/Wheel Systems, Colorado Springs, USA, August-September 2015.
-
Konferensbidrag (refereegranskat)abstract
- A methodology for numerical prediction of accumulated rail damage in railway turnouts is presented. Based onsimulation of dynamic vehicle‒track interaction followed by a discretisation of the conditions in each wheel‒railcontact, distributions of rail wear are calculated by the Archard model of sliding wear, while surface initiated rollingcontact fatigue (RCF) damage is evaluated by the Palmgren-Miner rule and an index building on shakedown theory.Partial slip in the wheel‒rail contacts and variable amplitude loading are considered. For freight traffic in the divergingroute, the influence of rail inclination and switch rail height on damage in the switch panel is investigated in ademonstration example. Two-point contact situations with one contact on the switch rail and one on top of the stock rail induce relative motion and slip between wheel and rail leading to high energy dissipation. In agreement with fieldobservations, it is concluded that wear is the dominating damage mechanism on the gauge side of the switch rail whilethe risk for RCF is higher on the crowns of the switch and stock rails. For accurate prediction of rail life for givencombinations of wheel/rail materials and traffic conditions, the methodology needs to be calibrated by fieldmeasurements.
|
|
| 3. |
- Andersson, Robin, 1986, et al.
(författare)
-
Integrated analysis of dynamic vehicle-track interaction and plasticity induced damage in the presence of squat defects
- 2015
-
Ingår i: Proceedings of the 10th International International Conference on Contact Mechanics and Wear of Rail/Wheel Systems, Colorado Springs, USA, August-September 2015.
-
Konferensbidrag (refereegranskat)abstract
- Despite significant efforts, the mechanisms behind the formation of squats – a form of rolling contact fatigue damage – are not fully understood. This study employs numerical simulations to investigate the propensity of squat initiation in the vicinity of small, isolated rail surface irregularities. Time domain dynamic vehicle–track interaction analysis is used to obtain wheel–rail contact stress distributions, which are mapped onto a continuum finite element model that accounts for plastic deformation of the rail material. The evaluated stress and strain fields are quantified using two RCF impact measures: accumulated effective strain and the Jiang-Sehitoglu multiaxial low cycle fatigue parameter. It is shown that the RCF impact increases with increasing size of the surface irregularity and that clustering of irregularities might strongly promote RCF. The friction coefficient is identified as a very influential parameter. Further, the effect of variations in friction along the rail is evaluated. It is shown that a short rail section of low friction results in fairly high RCF impact.
|
|
| 4. |
- Li, Xin, 1985, et al.
(författare)
-
Simulation of vertical dynamic vehicle-track interaction in a railway crossing using Green's functions
- 2017
-
Ingår i: Journal of Sound and Vibration. - : Elsevier BV. - 1095-8568 .- 0022-460X. ; 410, s. 318-329
-
Tidskriftsartikel (refereegranskat)abstract
- Vertical dynamic vehicle-track interaction in the through route of a railway crossing is simulated in the time domain based on a Green's function approach for the track in combination with an implementation of Kalker's variational method to solve the non-Hertzian, and potentially multiple, wheel-rail contact. The track is described by a linear, three-dimensional and non-periodic finite element model of a railway turnout accounting for the variations in rail cross-sections and sleeper lengths, and including baseplates and resilient elements. To reduce calculation time due to the complexity of the track model, involving a large number of elements and degrees-of-freedom, a complex-valued modal superposition with a truncated mode set is applied before the impulse response functions are calculated at various positions along the crossing panel. The variation in three-dimensional contact geometry of the crossing and wheel is described by linear surface elements. In each time step of the contact detection algorithm, the lateral position of the wheelset centre is prescribed but the contact positions on wheel and rail are not, allowing for an accurate prediction of the wheel transition between wing rail and crossing rail. The method is demonstrated by calculating the wheel-rail impact load and contact stress distribution for a nominal S1002 wheel profile passing over a nominal crossing geometry. A parameter study is performed to determine the influence of vehicle speed, rail pad stiffness, lateral wheelset position and wheel profile on the impact load generated at the crossing. It is shown that the magnitude of the impact load is more influenced the wheel-rail contact geometry than by the selection of rail pad stiffness.
|
|
| 5. |
- Torstensson, Peter T, 1981, et al.
(författare)
-
Dynamic train-track interaction at high vehicle speeds-Modelling of wheelset dynamics and wheel rotation
- 2011
-
Ingår i: Journal of Sound and Vibration. - : Elsevier BV. - 1095-8568 .- 0022-460X. ; 330:22, s. 5309-5321
-
Tidskriftsartikel (refereegranskat)abstract
- Vertical dynamic train-track interaction at high vehicle speeds is investigated in a frequency range from about 20 Hz to 2.5 kHz. The inertial effects due to wheel rotation are accounted for in the vehicle model by implementing a structural dynamics model of a rotating wheelset. Calculated wheel-rail contact forces using the flexible, rotating wheelset model are compared with contact forces based on rigid, non-rotating models. For a validation of the train-track interaction model, calculated contact forces are compared with contact forces measured using an instrumented wheelset. When the system is excited at a frequency where two different wheelset mode shapes, due to the wheel rotation, have coinciding resonance frequencies, significant differences are found in the contact forces calculated with the rotating and non-rotating wheelset models. Further, the use of a flexible, rotating wheelset model is recommended for load cases leading to large magnitude contact force components in the high-frequency range (above 1.5 kHz). In particular, the influence of the radial wheel eigenmodes with two or three nodal diameters is significant. (C) 2011 Elsevier Ltd. All rights reserved.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Torstensson, Peter T, 1981-, et al.
(författare)
-
Prognos över framtida kompetens- och resursbehov knutet till svensk infrastruktur för spårburen trafik : komplettering av prognosmodell
- 2021
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Detta PM redovisar resultatet från ett kompletteringsarbete av en sedan tidigare framtagen modell för prognostisering av framtida resurs- och kompetensbehov knutet till svensk infrastruktur för spårburen trafik.. PM:et motiverar valet av kompletterande åtgärder och beskriver utfört arbete. Slutligen presenteras och diskuteras förnyade prognosresultat. Valet av kompletterande åtgärder gjordes med utgångspunkt i Trafikverkets långsiktiga budgetplanering. Denna kombinerades med existerande kunskap om kostnadsandelen i planerade åtgärder som förväntas bli knuten till personal med järnvägsspecifik kompetens. Kompletterande åtgärder med potential att få betydande påverkan på prognosresultatet prioriterades. Slutligen valdes att lägga fokus för utvecklingsarbetet i det aktuella projektet på modelleringen av (1) nybyggnation av dubbel-/flerspår och enkelspår, (2) underhållsåtgärder och (3) åtgärder knutna till utbyggnationen av European Rail Traffic Management System (ERTMS).
|
|
| 9. |
- Torstensson, Peter T, 1981, et al.
(författare)
-
Simulation of rail roughness growth on small radius curves using a non-Hertzian and non-steady wheel–rail contact model
- 2014
-
Ingår i: Wear. - : Elsevier BV. - 0043-1648. ; 314:1-2, s. 241-253
-
Tidskriftsartikel (refereegranskat)abstract
- A time-domain model for the prediction of long-term growth of rail roughness (corrugation) on small radius curves is presented. Both low-frequency vehicle dynamics due to curving and high-frequency vehicle–track dynamics excited by short-wavelength rail irregularities are accounted for. The influence of non-Hertzian and non-steady effects in the wheel–rail contact model on rail wear is studied. The model features a contact detection method that accounts for wheelset yaw angle as well as surface irregularities and structural flexibilities of wheelset and rail. The development of corrugation on a small radius curve is found to be highly influenced by the wheel–rail friction coefficient. For vehicle speed 25 km/h and friction coefficient 0.3, predictions of long-term roughness growth on the low rail show decreasing magnitudes in the entire studied wavelength interval. For friction coefficient 0.6, roughness growth is found at several wavelengths. The corresponding calculation for the high rail contact of the trailing wheelset indicates no roughness growth independent of friction coefficient. The importance of accounting for the phase between the calculated wear and the present rail irregularity is demonstrated.
|
|
| 10. |
|
|
