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Keywords: Hertzian contacts, irregularities, impact loads, rigid rail, riding comfort, railway bridge.

Summary

The aim of this study is to simulate the dynamic vertical response of a vehicle traversing a rigid rail and railway bridge. This is achieved by using the authors' versatile contact elements to model the dynamic interaction between the wheels and the rail. The objective in creating these contact elements was to model the rail and wheel irregularities, which was not a feature of the contact elements in ANSYS (finite element program). A vertical spring is used to represent the interaction of the wheel with the rigid rail whereas the interaction of the wheel and flexible rail is much more complicated. The flexible rail is modelled as a series of beam elements and the interaction between the wheel and the beam element is represented by a series of matrices.

In previous works by Bowe & Mullarkey [1] they validated their system for a train crossing a single-track railway bridge on a smooth rail using ANSYS node-to- surface contact element. Excellent comparisons allowed them to pursue the ability to model irregularities on the track to create a more realistic vehicle-bridge model. This study focuses on the dynamic interaction of the vehicle as it traverses both the rigid rail and the railway bridge with and without the effects of irregularities. Pitching and rolling motion of the vehicle induced by the irregularities tend to decrease the riding comfort. Grandil and Ramondenc [2] recommend that the maximum vertical acceleration should not exceed 0.49 m/s² (=0.05 g), whereas Eurocode [3] allows a less strict limit of 1.0 m/s² in order for passengers to feel comfortable.

The system developed models each wheel as a spring element perpendicular to the surface of the rail. Three stiffness matrices are used to represent the action of the wheel on the flexible rail, whereas only one stiffness matrix is required to represent the action of the wheel on the rigid rail. The interaction between the spring and beam over which it is travelling has to be in accordance with Newton's third law. The beam acts with a vertical force on the spring element the spring element acts with an equal and opposite force on the beam.

Contact between the wheel and the rail is always maintained if the extension in the spring element is negative. However, if the extension in the spring element becomes positive, all the stiffness matrices related to that spring element are set equal to zero to simulate the wheel losing contact with the rail and subsequently the time-step is reduced.

Rail irregularities are introduced into the model to simulate realistic condition incurred by the wheels of a vehicle as it travels along the rail. Certain rail corrugations can cause both the rolling and pitching motion of the vehicle. If a wheel of a vehicle loses contact with the rail and then regains contact with the rail, this generally causes a sharp impact load to the structure.

In this paper only the centre span of the Boyne Viaduct railway bridge located in Drogheda, Ireland is considered. The bridge comprises a simply supported truss with pin-jointed connections, with a clear span of 80.77m and a total mass of approximately 275 tonnes. In our model the rail on the bridge is flexible, but the rail to the left and right of the bridge is rigid.

The vehicle model comprises a six-axle locomotive and a single four-axle railway carriage. Each vehicle consists of a vehicle body supported by a pair of bogies, with each bogie supported by axles and finally a pair of wheels supports each axle. The bogies are connected to the axles and the vehicle body respectively, through primary and secondary suspensions, which are comprised of springs and dashpots.

The purpose of this study was to examine the effects of the rolling and pitching motions of a vehicle caused by rail corrugations as it traversed the Boyne Viaduct railway bridge at different speeds. From our results it was shown that the bridge model is unchanged by the behaviour of the vehicle, whereas the different motions have different impacts on the passengers riding comfort.

References

1: C.J. Bowe, T.P. Mullarkey, "Bridge-train interaction incorporating rail & wheel irregularities and braking forces", Bridge Engineering Research in Ireland, 119-128, 2002.
2: J. Grandil, P. Ramondenc, "The dynamic behaviour of railways on high speed lines", SNCF, 1990.
3: European Committee for Standardization. EUROCODE 1: "Basis of design and actions on structures, Part 3: Traffic loads on bridges", ENV 1991-3, 1995.

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 77 PROCEEDINGS OF THE NINTH INTERNATIONAL CONFERENCE ON CIVIL AND STRUCTURAL ENGINEERING COMPUTING Edited by: B.H.V. Topping Paper 88 Wheel-Rail Contact Elements Incorporating Rail Irregularities C.J. Bowe and T.P. Mullarkey Department of Civil Engineering, National University of Ireland, Galway, Ireland doi:10.4203/ccp.77.88 purchase the full-text of this paper Full Bibliographic Reference for this paper C.J. Bowe, T.P. Mullarkey, "Wheel-Rail Contact Elements Incorporating Rail Irregularities", in B.H.V. Topping, (Editor), "Proceedings of the Ninth International Conference on Civil and Structural Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 88, 2003. doi:10.4203/ccp.77.88 Keywords: Hertzian contacts, irregularities, impact loads, rigid rail, riding comfort, railway bridge. Summary The aim of this study is to simulate the dynamic vertical response of a vehicle traversing a rigid rail and railway bridge. This is achieved by using the authors' versatile contact elements to model the dynamic interaction between the wheels and the rail. The objective in creating these contact elements was to model the rail and wheel irregularities, which was not a feature of the contact elements in ANSYS (finite element program). A vertical spring is used to represent the interaction of the wheel with the rigid rail whereas the interaction of the wheel and flexible rail is much more complicated. The flexible rail is modelled as a series of beam elements and the interaction between the wheel and the beam element is represented by a series of matrices. In previous works by Bowe & Mullarkey [1] they validated their system for a train crossing a single-track railway bridge on a smooth rail using ANSYS node-to- surface contact element. Excellent comparisons allowed them to pursue the ability to model irregularities on the track to create a more realistic vehicle-bridge model. This study focuses on the dynamic interaction of the vehicle as it traverses both the rigid rail and the railway bridge with and without the effects of irregularities. Pitching and rolling motion of the vehicle induced by the irregularities tend to decrease the riding comfort. Grandil and Ramondenc [2] recommend that the maximum vertical acceleration should not exceed 0.49 m/s² (=0.05 g), whereas Eurocode [3] allows a less strict limit of 1.0 m/s² in order for passengers to feel comfortable. The system developed models each wheel as a spring element perpendicular to the surface of the rail. Three stiffness matrices are used to represent the action of the wheel on the flexible rail, whereas only one stiffness matrix is required to represent the action of the wheel on the rigid rail. The interaction between the spring and beam over which it is travelling has to be in accordance with Newton's third law. The beam acts with a vertical force on the spring element the spring element acts with an equal and opposite force on the beam. Contact between the wheel and the rail is always maintained if the extension in the spring element is negative. However, if the extension in the spring element becomes positive, all the stiffness matrices related to that spring element are set equal to zero to simulate the wheel losing contact with the rail and subsequently the time-step is reduced. Rail irregularities are introduced into the model to simulate realistic condition incurred by the wheels of a vehicle as it travels along the rail. Certain rail corrugations can cause both the rolling and pitching motion of the vehicle. If a wheel of a vehicle loses contact with the rail and then regains contact with the rail, this generally causes a sharp impact load to the structure. In this paper only the centre span of the Boyne Viaduct railway bridge located in Drogheda, Ireland is considered. The bridge comprises a simply supported truss with pin-jointed connections, with a clear span of 80.77m and a total mass of approximately 275 tonnes. In our model the rail on the bridge is flexible, but the rail to the left and right of the bridge is rigid. The vehicle model comprises a six-axle locomotive and a single four-axle railway carriage. Each vehicle consists of a vehicle body supported by a pair of bogies, with each bogie supported by axles and finally a pair of wheels supports each axle. The bogies are connected to the axles and the vehicle body respectively, through primary and secondary suspensions, which are comprised of springs and dashpots. The purpose of this study was to examine the effects of the rolling and pitching motions of a vehicle caused by rail corrugations as it traversed the Boyne Viaduct railway bridge at different speeds. From our results it was shown that the bridge model is unchanged by the behaviour of the vehicle, whereas the different motions have different impacts on the passengers riding comfort. References 1 C.J. Bowe, T.P. Mullarkey, "Bridge-train interaction incorporating rail & wheel irregularities and braking forces", Bridge Engineering Research in Ireland, 119-128, 2002. 2 J. Grandil, P. Ramondenc, "The dynamic behaviour of railways on high speed lines", SNCF, 1990. 3 European Committee for Standardization. EUROCODE 1: "Basis of design and actions on structures, Part 3: Traffic loads on bridges", ENV 1991-3, 1995. purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £123 +P&P)
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