| 1. |
- Berghuvud, Ansel, et al.
(författare)
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Consequences of nonlinear characteristics of a secondary suspension in a three-piece freight car bogie
- 2001
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Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 36:1, s. 37-55
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Tidskriftsartikel (refereegranskat)abstract
- Mechanical systems with nonlinear characteristics can show a complex dynamic behavior that should be taken into account when analysing dynamic performance and reliability. The dynamic behavior of the main suspension in a three-piece freight car bogie with constant friction damping is considered in this work. The aim is to investigate the vertical behavior of a specific suspension design due to different driving conditions, weather and wear of the friction wedges. A variation in weather and wear is represented by different friction configurations in the model of the suspension. Models of different levels of detail that are based on experimental data on existing designs are developed. It is found that the suspension performance is very sensitive to variations of the friction configuration and this indicates a possible presence of nonlinear dynamic phenomena at in service like conditions
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| 2. |
- Berghuvud, Ansel
(författare)
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Curving performance and nonlinear dynamic behaviour of freight cars with three-piece bogies
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis considers modelling and simulation of the dynamic interaction between freight cars and railway track. The aim of the work is to study and enhance the knowledge and understanding of the nonlinear interaction for different heavy haul freight vehicle concepts of ore wagons applied at Malmbanan/Ofotbanen in northern Sweden and Norway. The thesis comprises an introductory part and five appended papers. The modelling of the vehicles is described, and a comparison is made between different design solutions for steady state curving performance with non-worn wheel and rail profiles on designed track geometry. The influence of worn rail profiles and braking on the curving performance is studied, and calculated lateral wheel-rail contact forces are compared with measured forces. The complex dynamic behaviour of parts of the system with nonlinear characteristics is also studied. In Paper A, the modelling of three different vehicles is described, and a comparison is made between different design solutions for steady state curving performance with non-worn wheel and rail profiles on designed track geometry. The vehicle-track interaction is modelled in a multibody system approach. The vehicle models take into account nonlinearities in the suspensions such as friction and mechanical play. The curving performance of the standard wagon is shown to be very dependent on the amount of friction in the primary suspension. The two other wagon types, and the standard wagon with low friction in its primary suspension, achieve good curving performance for the given conditions. In Paper B, the lateral wheel-rail contact forces are predicted for new and worn rail profiles. A model including multiple contact patches at wheel- rail interaction has been implemented in the system model. A modular structure is applied on the vehicle-track system model. The mean values of the predicted wheel-rail forces are compared with experimental results. A good agreement is achieved between the simulated results and the experimentally measured force levels, both for curving on new and worn rail. The lateral forces are shown to be much lower for running with non-worn wheels on new rail, than on worn rail. Significantly less wear is also predicted for the case with new rail. The importance of appropriate profile matching is shown. The influence of the coefficient of friction between wheels and rails on the curving performance is also shown. In paper C, the curving performance at braked conditions in downhill slopes is investigated. Three different bogie designs are compared. The model developed in Paper B is used as a basis for models of iron ore freight cars equipped with different types of three-piece bogie designs and pneumatically actuated single block tread brakes. The different designs are shown to have quite different responses to braking. The braking is however found unlikely to cause problems to the curving performance. In paper D, the behaviour of the vertical suspension including displacement limitations is studied. A single degree of freedom vehicle- track model is developed for the study, and a numerical investigation is made of the response to both sinusoidal and measured track irregularities. Nonlinear phenomena such as subharmonic motion and chaotic behaviour are found. The influence of impacts and the condition of the suspension on the dynamic range of the wheel-rail contact forces are also shown. In paper E, the dynamic behaviour of the secondary suspension for different driving conditions, weather and wear of the suspension is investigated. A single degree of freedom model as well as a detailed planar model of the suspension is developed and the system response is simulated. The suspension performance is found to be sensitive to variations in the friction configuration. The response is quite different for a perfectly symmetric friction distribution than for an asymmetric friction distribution between the wedges. Further, the response is also found to be sensitive to the time delay (phase) in excitation between the leading and following wheelset within the bogie.
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| 3. |
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| 4. |
- Berghuvud, Ansel, et al.
(författare)
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Dynamic behaviour of ore wagons in curves at Malmbanan
- 1998
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Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 30:3-4, s. 271-284
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Tidskriftsartikel (refereegranskat)abstract
- The transportation of ore can be made more cost efficient by use of bigger and heavier trains. An increase in axle load is thereby wanted. The fleet of ore wagons of today at Malmbanan/Ofotbanan in northern Sweden and Norway has to be updated. It is of interest to find out if it is possible to allow a higher axle load on the track with new wagons. To be able to understand and predict the effects on track wear depending on what type of vehicle that is in use, the contact forces between wheels and rails have to be determined. A computer aided analysis has been made of the dynamic behaviour of three test vehicles equipped with different types of three-piece bogies running at Malmbanan. The vehicles are modelled and their interaction with the track is analyzed using the multibody simulation package GENSYS. The simulations show that, even if the axle load is increased from 25 tons to 30 tons and the velocity is increased from 50 km/h to 60 km/h, it is possible to reduce lateral track forces and wear in curves by using a different bogie than the standard three-piece bogie used today
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| 5. |
- Berghuvud, Ansel
(författare)
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Freight car curving performance in braked conditions
- 2002
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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. ; 216:1, s. 23-29
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Tidskriftsartikel (refereegranskat)abstract
- Railway freight vehicles that are run with full payload on long downhill slopes with many tight curves must be braked more or less continuously. The influence of braking on the curving performance of iron ore freight cars equipped with different types of three-piece bogie designs and pneumatically actuated single-block tread brakes run on curved track in a downhill slope is investigated. The focus is put on the change in performance in terms of self-steering ability, track forces and expected wear in contacts between wheels and rails. Modelling and simulation of the strongly non-linear dynamic interaction between vehicle and track in braked conditions are performed. The large influence of wheel/rail profile matching and the quite different responses to braking for the studied vehicles are shown.
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| 6. |
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| 7. |
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| 8. |
- Berghuvud, Ansel, et al.
(författare)
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Prediction of lateral wheel-rail contact forces for ore wagons with three-piece bogies
- 1998
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Ingår i: Proceedings of the 6th Mini Conference on Vehicle System Dynamics, Identification and Anomalies. - Budapest : Techn. Univ.. - 9634206352 ; , s. 161-170
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Konferensbidrag (refereegranskat)abstract
- The transportation of ore can be made more cost efficient by use of bigger and heavier trains. An increased load on the track gives higher demands on both vehicle and infrastructure performance in order to limit the maintenance cost. At Malmbanan/Ofotbanen in Sweden and Norway there are many tight curves along the track experiencing high wear. One criterion for allowing a higher axle load is therefore to reduce the lateral track forces compared to the level of today. To evaluate the effect of an increased axle load, instrumented wheelset measurements were performed on different test vehicles of three-piece type. The measurements show essential variations in lateral force levels depending not only on curve radius and coefficient of friction in the wheel-rail contact, but greatly on the actual individual curve. This effect is studied in this work. The curving performance of one of the vehicles when running through curves with different rail profiles have been simulated. Both simulations and experimental results show large lateral forces for the typical situation on the studied track. The importance of matching wheel and rail profiles in order to get low contact forces and, as a consequence, less wear is shown.
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| 9. |
- Drugge, Lars, et al.
(författare)
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The nonlinear behaviour of a pantograph current collector suspension
- 1999
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Ingår i: Proceedings of the 1999 ASME Design Engineering Technical Conferences.
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Konferensbidrag (refereegranskat)abstract
- The pantograph-catenary system is a critical component for trains required to run at higher speeds. The pantograph often includes nonlinear characteristics and the scope of this work is to investigate if nonlinear dynamic phenomena can occur in an existing design. A model of a pantograph suspension subsystem has been developed according to physical parameter values of the head suspension of the Schunk WBL88/X2 pantograph, providing electric power to the Swedish high-speed train X2. Studies of the system response for different force excitation show both harmonic, subharmonic and chaotic behaviour for the investigated parameter regions.
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| 10. |
- Jamshid, Homayoun, et al.
(författare)
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Fusion of Digital Map Traffic Signs and Camera-detected Signs
- 2011
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Konferensbidrag (refereegranskat)abstract
- In this paper, we present several fusion approaches to merge speed limits reported in digital maps with detected speed limit signs using an onboard camera. Digital maps holding speed limits signs are required to be updated to cover speed limit changes and are unable to support variable speed limits. On the other hand, a camera system placed onboard a vehicular can detect variable speed limits as well as temporary speed limits at construction sites. However, an onboard camera cannot detect implicit speed limits. As such, a combination of digital map and camera system can provide more accurate speed limit information for driver assistance and support vehicle safety features. In this paper, the digital map and camera system are fused to obtain the desired more accurate speed limit information. The fused speed limits as well as those from the individual sources are compared with ground truth data obtained from an extensive measurement campaign spanning over 15000 km driving distance in five European countries. Specifically, five fusion approaches are defined, modeled and evaluated. Four of them are based on prioritizing information while the remaining approach is based on the classical Dempster-Shafer data fusion technique. The performance of the approaches are presented in terms of the percentage of correct speed limit detection with respect to the driving distance. The obtained results clearly show that fusion techniques can significantly increase the amount of correctly detected speed limits. A MATLAB based graphical user interface was designed to load test data, evaluate and present the results as fast and as efficient as possible.
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