Javier Carballeira

Rail corrugation growth accounting for the flexibility and rotation of the wheel set and the non-Hertzian and non-steady-state effects at contact patch

In this work, a simulation tool is developed to analyse the growth of rail corrugation consisting of several models connected in a feedback loop in order to account for both the short-term dynamic vehicle–track interaction and the long-term damage. The time-domain vehicle–track interaction model comprises a flexible rotating wheel set model, a cyclic track model based on a substructuring technique and a non-Hertzian and non-steady-state three-dimensional wheel–rail contact model, based on the variational theory by Kalker. Wear calculation is performed with Archards wear model by using the contact parameters obtained with the non-Hertzian and non-steady-state three-dimensional contact model. The aim of this paper is to analyse the influence of the excitation of two coinciding resonances of the flexible rotating wheel set on the rail corrugation growth in the frequency range from 20 to 1500 Hz, when contact conditions similar to those that can arise while a wheel set is negotiating a gentle curve are simulated. Numerical results show that rail corrugation grows only on the low rail for two cases in which two different modes of the rotating wheel set coincide in frequency. In the first case, identified by using the Campbell diagram, the excitation of both the backward wheel mode and the forward third bending mode of the wheel set model (B-F modes) promotes the growth of rail corrugation with a wavelength of 110 mm for a vehicle velocity of 142 km/h. In the second case, the excitation of both the backward wheel mode and the backward third bending mode (B-B modes) gives rise to rail corrugation growth at a wavelength of 156 mm when the vehicle velocity is 198 km/h.

Influence of the wheel-rail contact instationary process on contact parameters

The rapid convergence of the tangential rolling contact parameters to their stationary values, combined with the high computational cost associated with calculations using instationary models, has meant that stationary models are usually employed in railway dynamics. However, the validity of stationary models when the applied contact conditions are subjected to rapid changes has not been sufficiently investigated. With the objective of deducing the effects of the evolution of the instationary process on the contact parameters, the tangential contact problem is solved for a set of reference conditions. For this purpose a calculation model is adapted, from which it is possible to analyse the evolution of the contact parameters when the forces exerted between rail and wheel are subjected to rapid changes. From the calculations made, situations impossible to simulate by means of stationary theories are obtained according to the frequency of variation in the forces, such as slip zones in the leading edge of the contact area and reverse contact (locally, the traction field is opposite to the direction of the external force transmitted to the contact).

Method for obtaining the modal properties of articulated trains equipped with independently rotating wheels

Independently rotating wheels in railway vehicles could represent an alternative to standard technology as a solution to dynamic problems such as hunting instability or steering forces in curves. Among the proposed design solutions, the train with independently rotating wheels and with the most practical applications is that developed by Talgo. The Talgo technology is based on the use of a passive steering technique of the wheelset through a mechanism. The absence of automatic control systems means that a careful selection of the mechanical parameters of the vehicle is required to improve its dynamic characteristics. Aspects such as dynamic stability or the effect of vibration on passenger comfort could be analysed by extracting the modal properties of the train from mathematical models. In this article, a methodology for determining the low-frequency modal properties of articulated trains equipped with independently rotating wheels and passive steering system (Talgo-type) is proposed. The singularity of this application based on the use of non-conventional wheelsets necessarily involves the development of a specific methodology. †This article includes a word (Talgo) that is or is asserted to be a proprietary term or trade mark. Its inclusion does not imply it has acquired for legal purposes a non-proprietary or general significance, nor is any other judgement implied concerning its legal status.

Technical characteristics and dynamic modelling of Talgo trains

One main characteristic of Talgo trains from the very beginning in 1942 is the use of single-axle running gears with independently rotating wheels and non-active steering systems. This feature has allowed the use of other technical solutions that are usually more difficult to implement in conventional rolling stock, such as the lower coach floor, the automatic variable gauge system or the natural tilting technology. The present paper deals with the singularities in the modelling of the dynamic behaviour of Talgo trains, due to their particular characteristics.

Diseño de actividades y uso de la coevaluación para fomentar el desarrollo de competencias transversales en ingeniería mecánica y de materiales

En esta comunicacion se presentan las actividades de evaluacion desarrolladas en el marco de un Proyecto de Innovacion y Mejora Educativa, junto con algunos resultados preliminares. El principal objetivo de este proyecto es el diseno de actividades de evaluacion que fuercen a los estudiantes a desarrollar sus competencias transversales, al mismo tiempo que permitan a los profesores evaluar su desempeno en las competencias cientifico-tecnicas. Se emplea un enfoque de evaluacion formativa, de forma que las actividades de evaluacion sean utiles a los estudiantes para mejorar su aprendizaje. Palabras clave: competencias transversales, actividades de evaluacion, coevaluacion

Comparación de herramientas de evaluación de la competencia comunicación oral efectiva

El proyecto has sido financiado por el Vicerrectorado de Estudios, Calidad y Acreditacion de la Universitat Politecnica de Valencia a traves del programa PIME 2016-17 bajo la referencia A26.

Desarrollo de estrategias de evaluación de competencias transversales en asignaturas de ingeniería mecánica y de materiales

Por ultimo, los autores quieren agradecer la ayuda economica y el apoyo institucional recibidos de la Universitat Politecnica de Valencia a traves del proyecto PIME/2014/A/012/B.

Evaluación de competencias transversales en asignaturas relacionadas con Ingeniería Mecánica y de Materiales: Análisis y Resolución de Problemas, Aplicación y Pensamiento Práctico

Los autores quieren agradecer la ayuda economica y el apoyo institucional recibidos de la Universitat Politecnica de Valencia a traves del proyecto PIME/2014/A/012/B.

Propuesta de evaluación de las competencias de comunicación oral y escrita en asignaturas de Ingeniería Mecánica y Ciencia de Materiales

Los autores agradencen la financiacion recibida de la Universitat Politecnica de Valencia a traves del proyecto PIME/2014/A/012/B.

Enhancing Mechanism and Machine Science Learning by Creating Virtual Labs with ADAMS

This work presents a virtual lab created by using the multibody dynamics simulation software ADAMS\(^{\copyright }\), which has been developed to enhance the students experience when learning Mechanism and Machine Science fundamentals. When dealing with spatial kinematics and dynamics, there are some concepts which are usually difficult to visualize for the students. In this way, the use of a simulation software can help to overcome this problem. A set of exercises has been proposed in which the students have to build some models with ADAMS\(^{\copyright }\) and then solve some problems related to the theory. This proposal shows to be more attractive for the students, who learn the basics of an engineering tool that is commonly used in the industry and are able to visualize and consolidate the concepts taught at theory classes more easily. But there are also some drawbacks regarding the difficulties that appear when developing these exercises from the teaching point of view. The complexity of the program can complicate the creation of the models in a way that the students can not build them correctly and get the results expected. So, the exercises must be designed properly in order to make them robust enough to avoid these difficulties.