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ElsevierTur Valiente, M.; García, E.; Baeza González, LM.; Fuenmayor Fernández, FJ. (2014) AbstractIn this paper we propose a method of finding the initial equilibrium configuration of cable structures discretized by finite elements applied to the shape-finding of the railway overhead system. Absolute nodal coordinate formulation finite elements, which take into account axial and bending deformation, are used for the contact and messenger wires. The other parts of the overhead system are discretized with non-linear bars or equivalent springs. The proposed method considers the constraints introduced during the assembly of the catenary, such as the position of droppers, cable tension, height of the contact wire, etc. The main result of the shape-finding problem is the computation of the length of droppers. A comparison of the results obtained for reference catenaries in the bibliography is also included.

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A variety of methods have been proposed to calculate the dynamic response caused by a railway vehicle affected by a wheelflat. Most of the sophisticated procedures evaluate the elastic properties of the wheel-rail contact by means of the Hertz model. However, the hypotheses that must be satisfied in order to apply the Hertzian contact model are not fulfilled when the wheel-rail contact occurs in the area of wheel affected by the flat. This gives rise to deviations in the results of the dynamic model compared to the real situation. With the objective of analysing the influence of the elastic wheel-rail contact model, a procedure was developed to determine the dynamic response caused by a geometric irregularity (in rail or wheel) by means of Hertzian and non-Hertzian contact models. Results of the wheelflat impact simulations given by both types of contact model have been compared in this work.

The fatigue design of railway axles requires that the stresses arising in the axle in real service are accurately quantified. This paper describes a method to compute the dynamic stresses arising in railway axles as the effect of train-track interaction, based on the numerical simulation of the dynamic interaction between a flexible wheelset and a flexible track. The wheelset is modelled as a flexible rotating body using an Eulerian approach, whereas track is regarded as an infinite periodic system with the rail modelled as a Timoshenko beam resting on discrete elastic supports, considering the inertia associated with the sleepers.The paper presents an application of the proposed procedure to the calculation of the dynamic stresses caused in the axle by different types of geometric imperfection occurring on the wheel and rail surfaces, considering the cases of a single harmonic rail corrugation, random rail roughness and a wheelflat.

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Experimental theoretical methodology for determination of inertial pressure drop distribution and pore structure properties in wall-flow diesel particulate filters (DPFs). Energy. 36(12):6731-6744.