| 1. |
- Brabie, Dan, et al.
(författare)
-
On minimizing derailment risks and consequences for passenger trains at higher speeds
- 2009
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - 0954-4097 .- 2041-3017. ; 223:6, s. 543-566
-
Tidskriftsartikel (refereegranskat)abstract
- The first part of this article deals with the possibility of preventing wheel climbing derailments after an axle journal failure by implementing mechanical restrictions between the wheelsets and the bogie. A multi-body system (MBS) computer model is developed to account for such an axle failure condition, which is successfully validated by comparing the pre-derailment sequence of events with two authentic cases. An extensive parameter analysis on the maximum vertical and longitudinal play between the wheelset and the bogie, required to prevent a highspeed power or trailer car to derail, is performed for various combinations of running conditions in curves. Once an actual derailment has Occurred on conventional passenger trains at 200 km/h, extensive MBS simulations are performed on the feasibility of utilizing alternative substitute guidance mechanisms, such as low-reaching parts of bogie frame, axle box, or brake disc, as means of minimizing the lateral deviation. Results are presented in terms of geometrical parameters that lead to a successful engagement with the rail for a total of 12 different derailment scenarios. These are caused by an axle journal failure, an impact with a small object on the track, or a high rail failure. Minimizing the lateral deviation is also investigated by means of restraining the maximum Coupler yaw angle and altering the bogie yaw stiffness. Time-domain simulations are also performed in terms of lateral track forces and derailment ratio when negotiating a tight horizontal 'S-curve'. Further, the articulated train concept is investigated in terms of the post-derailment vehicle behaviour after derailments on tangent and curved track at a speed of 200 km/h. In this respect, a trainset consisting of one power car and four articulated passenger trailer cars is modelled in the MBS software. Results in terms of lateral deviation and maximum carbody roll angle are presented as a function of different inter-carbody damper characteristics and running gear features. The feasibility of these damper characteristics is also tested in terms of lateral track forces and derailment ratio when negotiating a tight horizontal S-curve.
|
|
| 2. |
- Diedrichs, Ben, et al.
(författare)
-
Crosswind stability of high-speed train on a high embankment
- 2007
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - 0954-4097 .- 2041-3017. ; 221:2, s. 205-225
-
Tidskriftsartikel (refereegranskat)abstract
- This work presents aerodynamic results of crosswind stability obtained numerically and experimentally for the leading control unit (class 808) of Deutsche Bahn AG's high-speed train Inter-CityExpress 2. The train model is on top of a 6 m high embankment in accordance with the proposed European code for interoperable trains, the so-called technical specifications for interoperability. The purpose of the study is to convey the predictive accuracy that typical steady-state computational fluid dynamics-Reynolds average Navier-Stokes methods (industry standard) return and to contribute to the understanding of the aerodynamics for the current application. Attention is drawn to the aerodynamics around the train and embankment when subjected to a steady block profile crosswind of 30 degrees yaw angle on the basis of the onset velocity far upstream the embankment. The Re (Reynolds number) of the embankment cases is 4.6 x 10(6). Calculated results are obtained with the commercial code STAR-CD, with exclusively hexahedral meshes with a total cell count of 13.5 x 10(6). Results are obtained when the train stands on the windward and leeward tracks on top of the embankment. These results are first compared with a flat ground case from a previous study. Then experimental data are obtained in a high-pressure wind tunnel with a model scale of 1:100. Re effects are compensated by raising the ambient pressure by a factor of 60, which increases the air density and thus the Re by a similar factor. Calculated results are in fair agreement with the experiments, where both the calculations and the experiments predict the leeward case to be the more critical one. In addition, the related consequences on the mechanical behaviour, i.e. the stability of the car, are briefly addressed by means of a quasi-static mechanical analysis. The results of the present study indicate that the 6 m high embankment concerning the current train reduces the permissible crosswind speed with approximately 20 per cent.
|
|
| 3. |
- Diedrichs, Ben, et al.
(författare)
-
Vehicle dynamics of a high-speed passenger car due to aerodynamics inside tunnels
- 2007
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - 0954-4097 .- 2041-3017. ; 221:4, s. 527-545
-
Tidskriftsartikel (refereegranskat)abstract
- High train speeds inside narrow double-track tunnels using light car bodies can reduce the ride comfort of trains as a consequence of the unsteadiness of the aerodynamics. This fact was substantiated in Japan with the introduction of the series 300 Shinkansen trains more than a decade ago, where the train speed is very high also in relatively narrow tunnels on the Sanyo line.The current work considers the resulting effects of vehicle dynamics and ride comfort with multi-body dynamics using a model of the end car of the German high-speed train ICE 2. The present efforts are different from traditional vehicle dynamic studies, where disturbances are introduced through the track only. Here disturbances are also applied to the car body, which conventional suspension systems are not designed to cope with.Vehicle dynamic implications of unsteady aerodynamic loads from a previous study are examined. These loads were obtained with large eddy simulations based on the geometry of the ICE 2 and Shinkansen 300 trains.A sensitivity study of some relevant vehicle parameters is carried out with frequency response analysis (FRA) and time domain simulations. A comparison of these two approaches shows that results which are obtained with the much swifter FRA technique are accurate also for sizable unsteady aerodynamic loads. FRA is, therefore, shown to be a useful tool to predict ride comfort in the current context.The car body mass is found to be a key parameter for car body vibrations, where loads are applied directly to the car body. For the current vehicle model, a mass reduction of the car body is predicted to be most momentous in the vicinity of 2 Hz.
|
|
| 4. |
- Enblom, Roger, et al.
(författare)
-
Proposed procedure and trial simulation of rail profile evolution due to uniform wear
- 2008
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - 0954-4097 .- 2041-3017. ; 222:1, s. 15-25
-
Tidskriftsartikel (refereegranskat)abstract
- A procedure for numerical simulation of rail wear and the corresponding profile evolution has been formulated. The wear is assumed to be uniform in the sense that the profiles remain constant along the track portion to be investigated. A simulation set is selected defining the vehicles running on the track, their operating conditions, and contact parameters. Several variations of input data may be included together with the corresponding occurrence probability. Simulation of multi-body dynamics is used to calculate contact forces and positions, and Archard's wear equation is applied for the calculation of wear depth. Wear coefficients as a function of contact pressure and relative sliding velocity are collected from different test results. Trial calculations of four non-lubricated and two lubricated curves with radii from 303 to 802 m show qualitatively reasonable results in terms of profile shape development and difference in wear mechanisms between gauge corner and rail head. The wear rates related to traffic tonnage are, however, overestimated and the lubrication efficiency underestimated. It is expected that model refinements in terms of environmental influence and contact stress calculation are useful to improve the quantitative results.
|
|
| 5. |
- Enblom, Roger
(författare)
-
Two-level numerical optimization of ride comfort in railway vehicles
- 2006
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - 0954-4097 .- 2041-3017. ; 220:1, s. 1-11
-
Tidskriftsartikel (refereegranskat)abstract
- This article addresses the interaction between and tuning of different mechanical subsystems in railway vehicle design. Application of numerical methods in a two-ievel optimization process, involving multi-body vehicle dynamics simulation and finite-element structural analysis, is proposed. The focus is on vibration ride comfort and tuning of dynamic properties of the vehicle, running gear, and carbody structure. As a background, a brief overview of multi-disciplinary and structural optimization methods is given. The selected solution based on the loosely coupled collaborative optimization approach, here implemented as a two-level structure, is presented. Numerical examples are provided to illustrate the choice of optimization algorithms suitable for this type of resonant systems and to demonstrate the performance of the numerical procedures on a realistic engineering problem. The leading coach of a three-car train-set is successfully optimized in terms of mass reduction and reduced natural frequency requirements, despite an infeasible initial design.
|
|
| 6. |
- Fröhling, Robert, et al.
(författare)
-
Guest editorial of Special Issue on High Tech in Heavy Haul
- 2009
-
Ingår i: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit. - : SAGE Publications. - 0954-4097 .- 2041-3017. ; 223, s. i-ii
-
Tidskriftsartikel (refereegranskat)
|
|
| 7. |
- Gianni, Andrea, et al.
(författare)
-
Bainitic steel grade for solid wheels: metallurgical, mechanical, and in-service testing
- 2009
-
Ingår i: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit. - 0954-4097 .- 2041-3017. ; 223:2, s. 163-171
-
Tidskriftsartikel (refereegranskat)abstract
- Bainitic steel grades generally have superior rolling contact and thermal fatigue resistances, but poorer wear characteristics when compared with ‘conventional’ pearlitic steel wheels. To improve the wear characteristics, the manufacturing process of bainitic materials needs to be carefully controlled. In this article, the manufacturing process of the ‘MICRALOS’ bainitic steel grade has been described. The main focus is on metallurgical testing activities performed in order to compare the new steel grade with standard pearlitic steels and to predict the service behaviour of the solid bainitic wheels. Further, on-going field tests on the iron ore line between Luleå and Narvik have been reported, with details about measurement methods and results. The performance of the wheels is reviewed and compared with the current scientific knowledge of bainitic steel grades and the deterioration of heavy haul wheels. Finally, benefits of and challenges for bainitic wheels in general and for the MICRALOS grade wheels in particular will be discussed.
|
|
| 8. |
- Granström, Rikard
(författare)
-
A system and stakeholder approach for the identification of condition information : a case study for the Swedish railway
- 2008
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - 0954-4097 .- 2041-3017. ; 222:4, s. 399-412
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of this paper is to identify stakeholders' need for system condition information in order to improve railway punctuality. The paper provides a holistic formulation of maintenance-related punctuality problems within the interface between the contact wire and the pantograph. From the identified problem formulation, the information needed to support the maintenance of technical functions can be identified. The incorporated system and stakeholder perspective adds a dimension to the explanation of what information is needed and why it is needed. The system and stakeholder perspective on the assessment of the information need can serve as decision support when acquiring new condition monitoring technologies. On the basis of the problem formulation, this perspective can also serve as an illustration of how information is to be used to improve punctuality. In order to identify stakeholders' need for system condition information, a failure mode and effects analysis (FMEA) approach was used. The FMEA is complemented with information derived from informal interviews performed with a variety of experts working with issues related to contact wires and pantographs. The applied methodology can be useful for conducting further research studies on other stakeholder and engineering interfaces, such as the wheel-rail interface.
|
|
| 9. |
- Harell, P., et al.
(författare)
-
Study of critical sections in catenary systems during multiple pantograph operation
- 2005
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - : SAGE Publications. - 0954-4097 .- 2041-3017. ; 219:4, s. 203-211
-
Tidskriftsartikel (refereegranskat)abstract
- To improve the dynamic behaviour of a catenary system, the sections that limit the speed have to be found. A survey was made to gather information about critical sections of the catenary-pantograph system. Interviews with personnel at the Swedish National Rail Administration were performed and problem areas that need consideration were found and are presented. The purpose of this study was to find out how much of these critical sections affect the system and to suggest improvements to the design. Section overlaps and section insulators, both in combination with the usage of multiple pantographs, were modelled, and simulations have been performed at different speeds and for different catenary systems. As a result of this research, a better base could be built on how to ease the operation with multiple pantographs.
|
|
| 10. |
- Jönsson, Per-Anders, et al.
(författare)
-
Experimental and Theoretical Analysis of Freight Wagon Link Suspension
- 2006
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - 0954-4097 .- 2041-3017. ; 220:4, s. 361-372
-
Tidskriftsartikel (refereegranskat)abstract
- Link suspension is the most prevailing suspension system for two-axle freight wagons and still frequently used for four-axle freight wagons in central and western Europe. The system design is simple and has existed for more than 100 years. However, still, the characteristics are not fully understood. This article focuses on the lateral characteristics of the link suspension. First, results from stationary measurements on freight wagons and laboratory tests on single links are presented. Then, a simulation mathematical model is proposed. Finally, the influence of various parameters on the link characteristics is investigated. With the developed simulation model, many of the stability problems of link suspension running gears can be explained, but further research is needed to fully understand the characteristics and to be able to recommend improvements. From the tests, it also becomes obvious that the characteristics of different links can vary significantly from each other depending on age and maintenance status.
|
|
