Equivalent Conicity and Curve Radius Influence on Dynamical Performance of Unconventional Bogies. Comparison Analysis

In this paper the dynamic behaviour of several unconventional bogies is compared. The study takes into account the radius of the curve and the maximum level of wear allowed to the wheels. Ranges of conicities and curve radius in which each bogie is advantageous are studied, for both high-speed and urban transit vehicles. Simulations have been carried out using an in house software that makes it possible to solve the wheel-rail contact problem in 3D, and to simulate accurately the negotiation of very sharp curves

Design of an optimised wheel profile for rail vehicles operating on two track gauges

This paper sets out an optimum synthesis methodology for wheel profiles of railway vehicles in order to secure good dynamic behaviour with different track configurations. Specifically, the optimisation process has been applied to the case of rail wheelsets mounted on double gauge bogies, that move over two different gauges, which also have different types of rail: the Iberian gauge (1668 mm) and the UIC gauge (1435 mm). Optimisation is performed using Genetic Algorithms and traditional optimisation methods in a complementary way. The objective function used is based on an ideal equivalent conicity curve which ensures good stability on straight sections and also proper negotiation of curves. To this end the curve is constructed in such a way that it is constant with a low value for small lateral wheelset displacements (with regard to stability), and increases as the displacements increase (to facilitate negotiation of curved sections). Using this kind of ideal conicity curve also enables a wheel profile to be secured where the contact points have a larger distribution over the active contact areas, making wear more homogeneous and reducing stresses. The result is a wheel profile with a conicity that is closer to the target conicity for both gauges studied, producing better curve negotiation while maintaining good stability on straight sections of track. The paper shows the resultant wheel profile, the contact curves it produces, and a number of dynamic analyses demonstrating better dynamic behaviour of the synthesised wheel on curved sections with respect to the original wheel.Spanish Research Ministry MICINN through contract TRA2010-18386 including the FEDER funds of the European Union. The Basque Government through IT-453-10 and Research Grant BFI08.172. UPV/EHU through the training and research unit UFI11/29

On the influence of conformity on wheel–rail rolling contact mechanics

The aim of this work is to assess the effects of conformity on local contact related quantities at the wheel–rail interface such as traction distributions, subsurface stresses and frictional work distributions. For this purpose conformal contact analyses are carried out by means of Finite Element (FE) models, and also with the exact rolling contact theory approach developed by Kalker, which has been appropriately adapted by the authors in order to take into account some of the effects of conformity. On the other hand, equivalent cases are analysed without taking into account the effects of conformity. In this way, the validity of the hypothesis of non-conformity is evaluated in different cases with varying degrees of conformity.Spanish Research Ministry MICINN/Economy and Competitiveness Ministry MINECO through contracts TRA2014-59599-R, including funding by the FEDER-ERDF European Regional Development Fund. Basque Government through IT.691-13-IT.919-16. The financial assistance received from UPV/ EHU through training and research unit UFI-11/29

On the non-proportionality between wheel/rail contact forces and speed during wheelset passage over specific welds

This study investigates the influence on the wheel-rail contact forces of the running speed and the shape and position of weld defects along the track. For this purpose, a vertical dynamic model in the space domain is used. The model is obtained from the transformation between the domains of frequency and space using a Rational Fraction Polynomials (RFP) method, which is modified with multiobjective genetic algorithms in order to improve the fitting of track receptance and to assist integration during simulations. This produces a precise model with short calculation times, which is essential to this study. The wheel-rail contact is modelled using a non-linear Hertz spring. The contact forces are studied for several types of characteristic welds. The way in which forces vary as a function of weld position and running speed is studied for each type of weld. This paper studies some of the factors that affect the maximum forces when the vehicle moves over a rail weld, such as weld geometry, parametric excitation and contact stiffness. It is found that the maximum force in the wheel-rail contact when the vehicle moves over a weld is not always proportional to the running speed. The paper explains why it is not proportional in specific welds.This work was partly financed by the European Horizon 2020 Joint Technology Initiative Shift2Rail through contract No 730841. The authors also wish to thank the Spanish Research Ministry MICINN/Economy and Competitiveness Ministry MINECO for their funding through contract TRA2014-59599-R, including funding by the FEDER-ERDF European Regional Development Fund, and also the Basque Government for financial assistance through IT919-16. The financial assistance received from UPV/EHU through the training and research unit UFI11/29 is likewise gratefully acknowledged

On the study of train-track dynamic interactions caused by rail welds on discrete supported rails

The paper studies the influence of rail weld dip on wheel-rail contact dynamics, with particular reference to freight trains where it is important to increase the operating speed and also the load transported. This has produced a very precise model, albeit simple and cost-effective, which has enabled train-track dynamic interactions over rail welds to be studied to make it possible to quantify the influence on dynamic forces and displacements of the welding geometry; of the position of the weld relative to the sleeper; of the vehicle's speed; and of the axle load and wheelset unsprung mass. It is a vertical model on the spatial domain and is drawn up in a simple fashion from vertical track receptances. For the type of track and vehicle used, the results obtained enable the quantification of increases in wheel-rail contact forces due to the new speed and load conditions.Spanish Research Ministry MICINN/Economy and Competitiveness Ministry MINECO through contract TRA2010-18386, including funding by the FEDER-ERDF European Regional Development Fund. Basque Government for financial assistance through IT-453-10 and IT-691-13 as well as for Research Grant BFI08.172. UPV/EHU through the training and research unit UFI11/29

A contact mechanics study of 3D frictional conformal contact

A contact mechanics study of three-dimensional conformal contact with friction is presented, based on numerical calculations with Finite Element models and an extension of Kalker's exact contact theory which takes into account the effects of conformity. Both the normal and the tangential parts of the contact problem are studied in situations with different conformity levels, up to total contact angle variations in the contact patch of about 100, assessing the particular characteristics brought about by conformity and the differences with respect to non conformal contact. The study may be of interest in important industrial applications where conformal contact may be found, such as rolling bearings or the wheel-rail case.This work has been partly financed within the European Horizon 2020 Joint Technology Initiative Shift2Rail through contract no. 730841. The authors wish to thank as well the Spanish Research Ministry MICINN/Economy and Competitiveness Ministry MINECO for their funding through contract TRA2014-59599-R, including funding by the FEDER-ERDF European Regional Development Fund, and also the Basque Government for financial assistance through IT919-16. The financial assistance received from UPV/EHU through the training and research unit UFI11/29 is likewise gratefully acknowledged

Approximating the influence coefficients of non-planar elastic solids for conformal contact analysis

The exact contact theory is an efficient alternative to the more general yet computationally expensive Finite Element Method for the detailed study of elastostatic contact problems. For its application in conformal contact problems, the exact contact theory needs to be fed with influence coefficients (ICs) appropriate for non-planar solids. An analytical approximation of the ICs for non-planar solids was proposed in a previous work, avoiding the involved process generally necessary to obtain ICs accurately. This work presents further developments of this approximation, further comparison with numerically obtained ICs, and evaluates the errors incurred when using approximated ICs in conformal contact.This work has been partly financed within the European Horizon 2020 Joint Technology Initiative Shift2Rail, through contract no. 826255 (IN2TRACK2). The authors wish to thank as well the Spanish Research Ministry MICINN/Economy and Competitiveness Ministry MINECO and MCI/AEI for their funding through contracts TRA2014-59599-R and PID2019-109483RB-I00, including funding by the FEDER-ERDF European Regional Development Fund, and also the Basque Government for financial assistance through IT919-1

A new overhang constraint for topology optimization of self-supporting structures in additive manufacturing

This work falls within the scope of computer-aided optimal design, and aims to integrate the topology optimization procedures and recent additive manufacturing technologies (AM). The elimination of scaffold supports at the topology optimization stage has been recognized and pursued by many authors recently. The present paper focuses on implementing a novel and specific overhang constraint that is introduced inside the topology optimization problem formulation along with the regular volume constraint. The proposed procedure joins the design and manufacturing processes into a integrated workflow where any component can directly be manufactured with no requirement of any sacrificial support material right after the topology optimization process. The overhang constraint presented in this work is defined by the maximum allowable inclination angle, where the inclination of any member is computed by the Smallest Univalue Segment Assimilating Nucleus (SUSAN), an edge detection algorithm developed in the field of image analysis and processing. Numerical results on some benchmark examples, along with the numerical performances of the proposed method, are introduced to demonstrate the capacities of the presented approach.This work was supported by The European Regional Development Fund (ERDF-FEDER) and the Ministry of Education and Science in Spain through the DPI2015-64863-R project (MINECO/FEDER-UE). The authors also wish to thank the Basque Government for financial assistance through IT919-16

Frictional contact analysis in a spherical roller bearing

Numerical analyses of the roller–raceway contact have been carried out in a spherical roller bearing using frictional contact models of different complexity. The models used in the study include an implementation of Kalker’s exact contact theory named CECT (Conformal Exact Contact Theory) and detailed Finite Element models. The adequacy of the more simplified contact solutions is assessed by contrasting them with the solutions obtained with the more comprehensive models. Additionally, the use of the exact contact theory, well known in the wheel–rail application, is demonstrated in contact mechanics analyses in rolling bearings, describing relevant details of its implementation for this application. Situations with different normal loads and friction levels have been analysed, and two distinct steady equilibrium configurations of the roller have been identified.J.B.-L., J.S., and E.G.V. gratefully acknowledge financial support from the European Horizon 2020 Joint Technology Initiative Shift2Rail through contracts 826255 and 101012456 (IN2TRACK2 and IN2TRACK3), from the Spanish Research Ministry MICINN/Economy and Competitiveness Ministry MINECO and MCI/AEI through contract PID2019-109483RB-I00, including funding by the FEDER-ERDF European Regional Development Fund, and from the Basque Government through IT1764-22

Programme for Harmonization to the International Scale in Latin America for BCR-ABL1 quantification in CML patients: Findings and recommendations

The quantitation of BCR-ABL1 mRNA is mandatory for chronic myeloid leukemia (CML) patients, and RT-qPCR is the most extensively used method in testing laboratories worldwide. Nevertheless, substantial variation in RT-qPCR results makes inter-laboratory comparability hard. To facilitate inter-laboratory comparative assessment, an international scale (IS) for BCR-ABL1 was proposed.The laboratory-specific conversion factor (CF) to the IS can be derived from the World Health Organization (WHO) genetic reference panel; however, this material is limited to the manufacturers to produce and calibrate secondary reference reagents. Therefore, we developed secondary reference calibrators, as lyophilized cellular material, aligned to the IS. Our purpose was both to re-evaluate the CF in 18 previously harmonized laboratories and to propagate the IS to new laboratories.Results Our field trial including 30 laboratories across Latin America showed that, after correction of raw BCR-ABL1/ABL1 ratios using CF, the relative mean bias was significantly reduced. We also performed a follow-up of participating laboratories by annually revalidating the process; our results support the need for continuous revalidation of CFs. All participating laboratories also received a calibrator to determine the limit of quantification (LOQ); 90% of them could reproducibly detect BCR-ABL1, indicating that these laboratories can report a consistent deep molecular response. In addition, aiming to investigate the variability of BCR-ABL1 measurements across different RNA inputs, we calculated PCR efficiency for each individual assay by using different amounts of RNA.Conclusions In conclusion, for the first time in Latin America, we have successfully organized a harmonization platform for BCR-ABL1 measurement that could be of immediate clinical benefit for monitoring the molecular response of patients in low-resource regions.Fil: Ruiz, María Sol. Fundación Cáncer. Centro de Investigaciones Oncológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sánchez, María Belén. Fundación Cáncer. Centro de Investigaciones Oncológicas; ArgentinaFil: Vera Contreras, Yuly Masiel. Fundación Cáncer. Centro de Investigaciones Oncológicas; ArgentinaFil: Agrielo, Evangelina. Laboratorio Especialidades Bioquímicas; ArgentinaFil: Alonso, Marta. Hospital Nacional Profesor Alejandro Posadas; ArgentinaFil: Altuna, María Eugenia. Clinica Roberto Raña; ArgentinaFil: Anchordoqui, María Sol. Argenomics; ArgentinaFil: Asinari, Mariana. Hospital Privado Centro Médico de Córdoba; ArgentinaFil: Bonetto, María Elisa. Hospital Rawson San Juan; ArgentinaFil: Camargo, Mauricio. Laboratorio Medellin; ColombiaFil: Giere, Isabel. Fundación Para Combatir la Leucemia; ArgentinaFil: González, Javier. Meyer Lab; ParaguayFil: Granda Alacote, Ana Cecilia. Laboratorios Medicos Lima; PerúFil: Guerra, Javier. Nanopharmacia Diagnóstica Mexico; MéxicoFil: Gutiérrez, Marina. Stamboulian; ArgentinaFil: Maldonado, Cecilia. Manlab; ArgentinaFil: Makiya, Ricard. No especifíca;Fil: Manrique, Gonzalo. Asociacion Española de Montevideo; UruguayFil: Monaco, María Eugenia. Laboratorio Tucuman; ArgentinaFil: Rozo, Juan Carlos. Unidad de Diagnóstico Hemato Oncológico; ColombiaFil: Santamaría Martín, Carlos Jose. Hospital de Niños San Jose de Costa Rica; Costa Rica. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Seravalle, Analía. Civic Rosario; ArgentinaFil: Zea, Olga. Laboratorio Medellin Colombia; ColombiaFil: Zubillaga, María Noel. Asociación Española de Socorros Mutuos; UruguayFil: Mordoh, José. Fundación Cáncer. Centro de Investigaciones Oncológicas; ArgentinaFil: Larripa, Irene Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Bianchini, Michele. Fundación Cáncer. Centro de Investigaciones Oncológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin