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Modelling and laboratory investigations on freight wagon link suspensions with respect to vehicle-track dynamic interaction
KTH, Superseded Departments, Aeronautical and Vehicle Engineering.
2004 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

The link suspension is the most prevailing suspension system for freight wagons in central and western Europe. The system design is simple and has existed for more than 100 years. However, still its characteristics are not fully understood. This thesis emphasizes freight wagon dynamics and comprises three parts:

In the first part a review of freight wagon running gear is made. The different suspension systems are described and their advantages and disadvantages are discussed. The review covers the running gear standardized by UIC and the conventional so-called three-piece bogie. Additionally five improved three-piece bogies and twelve novel running gear designs are presented.

The second part focuses on the lateral force-displacement characteristics in the link suspension. Results from stationary measurements on freight wagons and laboratory tests of the link suspension characteristics are presented. To improve understanding of the various mechanisms and phenomena in link suspension systems a simulation model is developed. Link suspension systems have strongly nonlinear characteristics including a hysteresis loop. The loop exhibits usually three characteristic sections with different tangential stiffnesses. The actual contact geometry of the links and end bearings has a significant influence on the characteristics. By wear in ordinary service - as well as by geometric tolerances on new components - the contact geometry may deviate considerably from nominal geometry. Further, it seems that elastic deformation in the contact surfaces has considerable effects on the suspension characteristics, in particular on the initial rolling stiffness for small displacements. Also, flexibilities in links and end bearings influence the characteristics. It is also observed that new components after a short period of dynamic testing can exhibit a very low amount of energy dissipation, a phenomenon that is also indicated in some stationary measurements on wagons.

To summarize the second part, it appears that the link suspension characteristics are very sensitive to several factors being hard to control in the real world of freight wagon operations. The various stiffnesses and hysteresis loops have a considerable variation and may have a strong influence on the ride qualities of vehicles. As long as the characteristics can not be controlled within closer limits than found in this study, there is a strong need for sensitivity analysis to be made, both in predictive multibody simulations of vehicle dynamics, as well as in verification and acceptance tests.

In the third part a study on the possibility to improve ride qualities of freight wagons with link suspensions is presented. Parametric studies with multibody dynamic simulations on freight wagons equipped with link-suspension bogies are performed. The effect of supplementary friction and hydraulic damping is investigated under various running conditions: speed, loading, tangent and curved track, wheel-rail contact geometry, track gauge and track irregularities. Substantial improvements of the lateral running behaviour of wagons with link suspension bogies can be achieved - both at ordinary speeds and at increased speeds - by using a proper combination of supplementary hydraulic dampers. Speeds up to 160 km/h could be realistic.

Place, publisher, year, edition, pages
2004.
Series
Trita-AVE, ISSN 1651-7660 ; 2004:48
Keyword [en]
railway, freight wagon, running gear, link suspension, laboratory test;
National Category
Other Materials Engineering
Identifiers
URN: urn:nbn:se:kth:diva-395ISBN: 91-7283-806-X (print)OAI: oai:DiVA.org:kth-395DiVA: diva2:10154
Presentation
2004-12-17, 10:15
Available from: 2005-08-12 Created: 2005-08-12 Last updated: 2012-03-20
List of papers
1. Experimental and Theoretical Analysis of Freight Wagon Link Suspension
Open this publication in new window or tab >>Experimental and Theoretical Analysis of Freight Wagon Link Suspension
2006 (English)In: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, Vol. 220, no 4, 361-372 p.Article in journal (Refereed) Published
Abstract [en]

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.

Keyword
Freight wagon; Friction damping; Hysteresis; Link suspension; Non-linear dynamics; Running gear; Stiffness; Suspension; Wheel-rail dynamics
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-7370 (URN)10.1243/09544097JRRT75 (DOI)000243454500003 ()2-s2.0-34247134506 (Scopus ID)
Note
QC 20100802Available from: 2007-07-13 Created: 2007-07-13 Last updated: 2010-08-02Bibliographically approved
2. Influence of link suspension characteristics variation on two-axle freight wagon dynamics
Open this publication in new window or tab >>Influence of link suspension characteristics variation on two-axle freight wagon dynamics
2006 (English)In: Vehicle System Dynamics, ISSN 0042-3114, Vol. 44, no Supplement 1, 415-423 p.Article in journal (Refereed) Published
Abstract [en]

The link suspension is the most prevailing suspension system for freight wagons in central and western Europe. Link suspension systems have strong non-linear characteristics including a hysteresis loop. The loop exhibits usually three characteristic sections with different tangential stiffnesses. The actual contact geometry of the links and end bearings has a significant influence on the characteristics. By wear in ordinary service. the contact geometry changes considerably, thus causing the characteristics to change. In summary, it appears that the link suspension characteristics are very sensitive to several factors. being hard to control in the real world of freight wagon operations. The various stiffnesses and hysteresis loops are found to have a strong influence on the ride qualities of vehicles. This paper presents non-linear multibody simulations investigating these matters. As long as the characteristics cannot be controlled within closer limits than found in this study, there is a strong need for the sensitivity analysis to be made, both in predictive multibody simulations of vehicle dynamics as well as for verification and acceptance tests.

Keyword
Dynamics; Freight wagon; Link suspension; Ride quality; Simulation; Test; Automobile suspensions; Dynamics; Freight cars; Hysteresis; Hysteresis loops; Magnetic materials; Sensitivity analysis; Stiffness
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-7371 (URN)10.1080/00423110600872416 (DOI)000244729300040 ()2-s2.0-65249090788 (Scopus ID)
Note
QC 20100802Available from: 2007-07-13 Created: 2007-07-13 Last updated: 2011-10-03Bibliographically approved

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