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Mechanical Engineering, Dynamic simulation, Resistance test, Acceptance testing, Lateral stiffness, Automotive engineering, Friction coefficient, Engineering, business.industry, business, Bogie, Damper, and Suspension (vehicle)

A more widespread use of the dynamic simulation of rail vehicles would become possible if the validation of the model was secured and the model parameters were known to be accurate. This paper proposes an analytical methodology for the objective identification of parameter values used in modelling rail vehicles, using the results of a bogie rotational resistance test defined in the acceptance process of railway vehicles (EN 14363). This methodology also takes into account the variability of the measuring process by providing a probabilistic estimation of the identified parameters. The methodology is experimentally validated using test results obtained for an Intercity vehicle. Seven model parameters can be accurately estimated: longitudinal and lateral stiffness of the air-spring secondary suspension, damping and force–speed characteristics of the anti-yaw dampers, longitudinal and lateral stiffness of the emergency spring, and lateral/longitudinal friction coefficient of the emergency spring; they all show excellent correlation with the component tests.

Impresión 3D, FDM, ABS, Makerbot Replicator 2X, resistencia a la tracción, 3D printing, fused deposition modelling, mechanical properties, General Engineering, Humanities, Manufacturing process, Physics, and 3d printer

espanolLa impresion 3D es un proceso de manufactura que se basa en la fabricacion de prototipos, partes y piezas funcionales. Existen diferentes metodos, en los cuales se utilizan distintos materiales en diversos formatos. Uno de los metodos mas utilizados es el Modelado por Deposicion Fundida (FDM). A pesar de las ventajas que posee con respecto a otros procesos de fabricacion, la impresion 3D no esta libre de dificultades o problemas. Una de las principales problematicas se presenta al momento de configurar una impresion y tiene relacion con la eleccion de los parametros de impresion. En ocasiones, la eleccion se realiza en funcion de la experiencia de los operadores, pero cuando se requieren propiedades especificas, no se conocen los parametros a elegir. En este trabajo, se analizo la influencia del porcentaje de relleno en la resistencia a la traccion de piezas fabricadas en ABS, con una impresora Makerbot Replicator 2X. Para ello, se imprimieron probetas para ensayos de traccion, variando el porcentaje de relleno, manteniendo los demas parametros constantes. Luego fueron ensayadas y de esta manera se logro obtener la propiedad mecanica de resistencia a la traccion. Ademas, se analizo el tiempo efectivo de impresion, logrando establecer un rango recomendado de impresion en funcion de este parametro combinado con la resistencia a la traccion. La maxima resistencia a la traccion promedio, se obtuvo con un porcentaje de relleno de 100% y fue de 34,57 [MPa] English3D printing is manufacturing process that consists of the fabrication of prototypes, parts and functional pieces. Several methods can be used, with different materials in different formats. One of the most popular techniques is the Fused Deposition Modelling (FDM). This method has several advantages with respect to other manufacturing processes, although it also has some problems and difficulties. One of these problems arises when setting the printing parameters. Generally, the printing parameters are selected according to the user’s experience, although it is rather difficult to adapt the parameter settings in order to obtain specific mechanical properties of the printed parts. This work, analyzes the influence of infill on the tensile strength in parts printed with ABS, using a Makerbot Replicator 2X 3D printer. Test specimens were printed, modifying the infill, while maintaining the other parameters constant. Afterwards, the test specimens were tested in a traction test obtaining the tensile strength. In addition, the effective impression time was analyzed, in order to obtain a recommended infill ranges of impression time and tensile strength. Results showed that the maximum tensile strength was 34.57 [MPa] considering a 100% infill.

Mechanical Engineering, Safety, Risk, Reliability and Quality, Automotive Engineering, Normal mode, Poison control, Acceptance testing, Vibration, Engineering, business.industry, business, Mathematical model, Suspension (vehicle), Control theory, Stiffness, medicine.symptom, medicine, Modal analysis, Simulation, and Computer Science::Robotics

The validation of vehicle mathematical models is a key part of the virtual acceptance process since it is essential to ensure a precise representation of the reality. The model validation procedure should include validation of stationary but also dynamic tests. However, parameter identification from on-track tests is a challenging task due to the non-controlled excitation and the great variability of the test results. Thus, an alternative solution by means of a vehicle modal analysis is proposed, developing a parameter identification methodology for dynamic vehicle model parameters. This methodology calculates estimated values of the vehicle model parameters that have an influence on the excited vehicle vibration modes. Moreover, a new criterion for taking into account the effect of the measurement uncertainties on the selection process of the vehicle parameters is developed. Finally, experimental results show that not only estimations of the suspension stiffness parameters can be obtained, but damping values and structural frequencies from the vehicle bodies can also be estimated.

Ingeniería y Tecnología, Ingeniería Mecánica, Mecánica Aplicada, Rail vehicle models, and crosswind stability

La influencia del viento lateral en el descarrilamiento de los vehiculos ferroviarios es un factor critico desde que se comenzaron a producirvehiculos ligeros que circulan a altas velocidades Ademas el confort del pasajero tambien puede verse afectado por el viento lateral Sinembargo este efecto todavia no ha sido investigado en profundidad en la literatura ferroviaria Este articulo describe el efecto del vientolateral en el confort para trenes de alta velocidad que circulan en curvas para diferentes velocidades de viento utilizando un escenario deviento tipo sombrero chino Las simulaciones muestran que la combinacion del viento lateral y la rigidez del tope de la suspensionsecundaria pueden suponer una fuente importante de inestabilidad produciendo contacto pestanapestana y disminuyendosignificativamente el confort Ademas este efecto se produce cuando el indice de descarrilamiento esta muy por debajo del limite segun lanorma de seguridad ferroviaria

62 Ingeniería y operaciones afines / Engineering, Rail vehicle models, crosswind stability, ride quality, lcsh:Technology, lcsh:T, lcsh:Mining engineering. Metallurgy, lcsh:TN1-997, General Engineering, Vehicle safety, Train, Automotive engineering, Crosswind, Ride quality, Suspension (vehicle), Engineering, business.industry, business, Stiffness, medicine.symptom, medicine, modelos de vehículos ferroviarios, estabilidad con viento lateral, and confort

The effect of crosswinds on the risk of railway vehicles overturning has been a major issue ever since manufacturers began to produce lighter vehicles that run at high speeds. However, ride comfort can also be influenced by crosswinds, and this effect has not been thoroughly analyzed. This article describes the effect of crosswinds on ride comfort in high speed trains when running on curves and for several wind velocities under a Chinese hat wind scenario, which is the scenario recommended by the standard. Simulation results show that the combination of crosswinds and the added stiffness of the lateral bumpstop on the secondary suspension can become a significant source of instability, leading to flange-to-flange contact and greatly jeopardizing ride comfort. Moreover, this comfort problem is an issue even when the wheel unloading ratio is well below the standard's limits and vehicle safety can be guaranteed. La influencia del viento lateral en el descarrilamiento de los vehículos ferroviarios es un factor crítico desde que se comenzaron a producir vehículos ligeros que circulan a altas velocidades. Además, el confort del pasajero también puede verse afectado por el viento lateral. Sin embargo, este efecto todavía no ha sido investigado en profundidad en la literatura ferroviaria. Este artículo describe el efecto del viento lateral en el confort para trenes de alta velocidad que circulan en curvas para diferentes velocidades de viento, utilizando un escenario de viento tipo sombrero chino. Las simulaciones muestran que la combinación del viento lateral y la rigidez del tope de la suspensión secundaria pueden suponer una fuente importante de inestabilidad, produciendo contacto pestaña-pestaña y disminuyendo significativamente el confort. Además, este efecto se produce cuando el índice de descarrilamiento está muy por debajo del límite según la norma de seguridad ferroviaria.

Mechanical Engineering, Probabilistic estimation, Control theory, Automotive engineering, Acceptance testing, Engineering, business.industry, business, Scale model, Coupling effect, Suspension (vehicle), Stiffness, medicine.symptom, medicine, Model building process, and Model parameters

The accuracy of multi-body simulation results relies on the model building process and the accuracy of the model parameters. A more widespread use of vehicle dynamic calculations in the acceptance process would be possible if the validation of the model was secured. This paper proposes a methodology for an objective and direct identification of the values of the parameters of a rail vehicle model, using the results of the stationary tests defined in the acceptance process of railway vehicles (EN14363). The methodology also takes into account the variability of the measuring process by providing a probabilistic estimation of the identified parameters. The methodology is validated using an example of a virtual wheel unloading test (simulation). Four significant model parameters can be accurately calculated: vertical primary and secondary suspension stiffness, stiffness of the anti-roll bar, and height of the null moment point (the lateral/roll coupling effect of the air spring). Finally, a reduction method is shown which decreases the uncertainties of the identified parameters by up to 50%.