Aparato y procedimiento para medir la deformación en un ensayo de tracción.

Aparato para medir la deformación por tracción de una probeta, que comprende: un brazo articulado configurado para fijarse a una máquina de ensayo, donde dicho brazo articulado comprende al menos dos tramos rígidos, y medios de anclaje; una guía montada en un extremo del segundo tramo del brazo articulado. Sobre dicha guía están montados dos bastidores en forma de "U", donde cada uno de dichos bastidores porta un sensor óptico respectivo, cada uno de los cuales tiene capacidad para desplazarse a lo largo de dicha guía; donde en el interior de la "U" de dichos soportes se aloja una probeta, incluyendo dos objetivo fijables a dicha probeta, estando dichos objetivos configurados para mediar la deformación de dicha probeta mediante la medición por parte de dichos sensores ópticos del desplazamiento de dichos objetivos.Solicitud: 201100377 (28.03.2011)Nº Pub. de Solicitud: ES2364212A1 (29.08.2011)Nº de Patente: ES2364212B1 (06.07.2012

Predicción del módulo de elasticidad de la poliamida reciclada reforzada con fibra de vidrio

Este trabajo plantea un modelo para predecir el módulo de elasticidad de la poliamida 6.6 reforzada con un 35% en peso de fibra corta de vidrio reciclada, en estado seco, en función del número de reinyecciones. El estudio se basa en una modificación del modelo analítico simplificado de Templeton. La aproximación planteada propone la incorporación de dos nuevos coeficientes que consideran la degradación sufrida por la matriz termoplástica. El modelo analítico desarrollado mantiene los efectos asociados a la fibra como su desorientación y acortamiento durante la reinyección así como la eficacia del agente adherente en la interfase fibra-matriz, ya evaluado por otros autores. La novedad de este estudio radica en aportar el efecto añadido de la degradación de la matriz polimérica, medida a través de la variación de su viscosidad y temperatura de transición vítrea sobre el comportamiento mecánico del compuesto.This work proposes a model to predict the modulus of elasticity of recycled polyamide 6.6 reinforced with 35% by weight of short fiberglass, in the dry as moulded (DAM) conditions, which is based on the number of reinjections. The study is a modification of the simplified analytical model of Templeton. The proposed approach incorporates two new coefficients that consider the degradation suffered by the thermoplastic matrix. The developed analytical model maintains the effects associated to the fiber as its disorientation and shortening during reinjection as well as the effectiveness of the adherent agent in the fiber - matrix interface, already evaluated by other authors. The novelty of this study is that provides the added effect of degradation of the polymer matrix, measured through the variation of its viscosity and glass transition temperature,on the mechanical behavior of the compound

Experimental validation of an adjustable railway fastening for slab track

ABSTRACT: A railway infrastructure capable of supporting a high frequency of light and heavy traffic, sometimes at high speed, requires the implementation of a high quality track. A correct definition of all track components leads to a high degree of safety and comfort for travelers as well as reduced operating costs. One factor that determines the elastic behaviour of the track is the rail fastening system. In this paper, the mechanical, electrical, and environmental sustainability characterization tests based on European standards UNE-EN have been carried out, verifying that the TK04 fastening system with a lateral adjustment of ±1 cm, manufactured by ThyssenKrupp Gleistechnik GmbH, satisfies the conditions and requirements of European standards UNE-EN for installation on slab track systems for light rail

Micromecanismos de fallo de aceros estructurales durante la galvanización en caliente.

Este artículo presenta un modelo que explica las diferentes etapas que ocurren en un proceso de fallo de un acero estructural durante la galvanización en caliente en discontinuo, desde la etapa de fluxado hasta la rotura total de la pieza o la parada de fisura. El modelo describe el proceso como un fallo por metal líquido, ayudado por el efecto fragilizante del hidrógeno, catalizador de las reacciones hierro-zinc. Se distingue entre dos casos, uno en el que el baño de galvanización tiene más de un 0,5 % de Sn, en el que se forma el compuesto intermetálico FeSn en el frente de fisura, y otro en el que el contenido de Sn en el baño de metal líquido es menor a ese 0,5 %, en el que se forman las fases Fe-Zn habituales. Se imponen dos condiciones mecánicas para que se produzca el fallo, que el factor de intensidad de tensiones sea creciente y a la vez superior al umbral, KIscc. Esas restricciones mecánicas sirven como criterio para dar algunas recomendaciones a galvanizadores para evitar el fallo, y también para reevaluar la bondad de recomendaciones de otras fuentes bibliográficas que han surgido en los últimos años, y de las que se hace un pequeño resumen

Sistema para el ensayo de cargas de fatiga de tracción y compresión sobre los elementos de sujeción de una vía ferroviaria dentro del mismo ciclo de carga

Sistema para el ensayo de cargas de fatiga de tracción y compresión sobre los elementos de sujeción de una vía ferroviaria dentro del mismo ciclo de carga, que comprende: - una sección de carril con una abertura a lo largo del eje longitudinal de su cabeza, que presenta a su vez una porción cortada; - traviesas y elementos de sujeción característicos de una vía ferroviaria: - una barra cilíndrica situada atravesando la abertura de la cabeza, de una longitud tal que los extremos de la barra cilíndrica se sitúan fuera de la abertura, y tal que parte de la barra cilíndrica es visible debido a la porción cortada; - una horquilla que comprende un orificio, tal que la barra cilíndrica se sitúa atravesando dicho orificio: estando el sistema configurado para acoplarse a una máquina de ensayos, por medio de un aplicador permitiendo así la aplicación de fuerzas de tracción y compresión con diferentes grados de inclinación sobre la barra cilíndrica, y por ende, sobre el carril, las traviesas y los elementos de sujeción de la vía ferroviaria.Solicitud: 201700509 (31.03.2017)Nº Pub. de Solicitud: ES2665577A1 (26.04.2018)Nº de Patente: ES2665577B2 (21.08.2018

Quantification of Kraft paper ageing in mineral oil impregnated insulation systems through mechanical characterization

Power transformers use Kraft paper, thermally upgraded Kraft and other polymeric papers (ex. Nomex) as the main solid insulation between the winding conductors. Dielectric oil used in transformers as an insulating and cooling fluid typically has an operating temperature range of 60–90 °C. These service temperatures can cause slow degradation of both the oil and the insulating paper winding, with a loss of mechanical and dielectric properties. In this sense, this work analyzes paper degradation through Young’s Modulus, yield stress, rupture strength and strain under ultimate strength. An accelerated thermal ageing of the paper in mineral oil was carried out at temperatures of 110, 130 and 150 °C over different periods of time, in order to obtain information on the kinetics of the ageing degradation of the paper. The evolution of the mechanical properties and micro mechanisms of paper failure are analysed as a function of temperature and ageing time. Finally, the results obtained are compared with the traditional method of degradation analysis, based on the degree of polymerisation measurement.The authors are grateful for the funding received to carry out this work from the State Scientific and Technical Research and Innovation Plan under the DPI2013-43897-P Grant Agreement, financed by the Government of Spain

Determination of the optimum amount of superplasticizer additive for self-compacting concrete

ABSTRACT: Self-compacting concrete modifies its workability with small variations in the amount of superplasticizer additive. For this reason, large number of tests are required to monitor its workability. In order to determine the appropriate amount of additive for a single mix, the evolution of the power consumption of the concrete mixer during the addition of small amounts of additive to the concrete was analyzed. These results were compared both with typical workability characterization for self-compacting concrete and with the saturation point results, determined by the Marsh cone method. After this comparison, a good correlation was obtained between the results from the traditional tests and the proposed ?concrete mixer method?Funding: This research was funded by Spanish Ministry of Economy and Competitiveness of Spain, grant number MAT2014-57544-R”

Machine learning algorithms for the prediction of the mechanical properties of railways' rail pads

ABSTRACT: Train operations generate high impact and fatigue loads that degrade the rail infrastructure and vehicle components. Rail pads are installed between the rails and the sleepers to damp the transmission of vibrations and noise and to provide flexibility to the track. These components play a crucial role to maximize the durability of railway assets and to minimize the maintenance costs. The non-linear mechanical response of this type of materials make it extremely difficult to estimate their mechanical properties, such as the dynamic stiffness. In this work, several machine learning algorithms were used to determine the dynamic stiffness of pads depending on their in-service conditions (temperature, frequency, axle-load and toe-load). 720 experimental tests were performed under different realistic operating conditions; this information was used for the training, validation and testing of the algorithms. It was observed that the optimal algorithm was gradient boosting for EPDM (R2 of 0.995 and mean absolute percentage error of 5.08% in test dataset), TPE (0.994 and 2.32%) and EVA (0.968 and 4.91%) pads. This algorithm was implemented in an application, developed on Microsoft. Net platform, that provides the dynamic stiffness of the pads characterized in this study as function of material, temperature, frequency, axle-load and toe-load

Structural integrity assessment of a nuclear vessel through ASME and master curve approaches using irradiation embrittlement predictions

ABSTRACT: The assessment of the structural integrity of nuclear vessels is based on a series of procedures developed in the 1970s and 1980s. On one hand, curves that, according to the American Society of Mechanical Engineers code, describe the relationship between steel toughness and temperature in the ductile-to-brittle transition region, based on the reference temperature concept RTNDT, were adopted in 1972. On the other hand, the material embrittlement derived from the exposure of steel to neutron irradiation is determined through the model included in “Regulatory Guide 1.99 Rev. 2,” published in 1988. Since then, there have been enormous advances in this field. For example, the Master Curve, based on the reference temperature T0, describes the relationship between toughness and temperature in the transition zone more realistically and with much more robust microstructural and mechanical foundations and uses the elastic-plastic fracture toughness KJc. Moreover, improved models have been developed to estimate the embrittlement of steel subjected to neutron irradiation, such as ASTM E900, Standard Guide for Predicting Radiation-Induced Transition Temperature Shift in Reactor Vessel Materials. This study is aimed at comparing the results obtained using traditional procedures to the improved alternatives developed later. For this purpose, the behavior of the steel of a nuclear vessel that is currently under construction has been experimentally characterized through RTNDT and T0 parameters. In addition, the material embrittlement has been quantified using “Regulatory Guide 1.99 Rev. 2” and ASTM E900. These experimental results have been transferred to the assessment of the structural integrity of the vessel to determine the pressure-temperature limit curves and size of the maximum admissible defect as a function of the operation time of the plant. The results have allowed the implicit overconservatism present in the traditional procedures to be quantified.This project was carried out with the financial support of Sociedad para el Desarrollo Regional de Cantabria (SODERCAN) and Equipos Nucleares S.A. (ENSA), to whom the authors would like to express their gratitude

Utensilio para ensayos de corrosión bajo tensión.

Utensilio para ensayos de corrosión bajo tensión caracterizado por estar adaptado a probetas de tenacidad a fractura y probetas de ensayos mecánicos, sumergidas horizontalmente en un ambiente agresivo y por estar acoplado a una máquina universal de ensayos en disposición vertical. El utensilio resuelve el problema técnico de realizar ensayos de corrosión bajo tensión con probetas en disposición horizontal cuando sólo se dispone de máquinas universales de ensayos en disposición vertical. El utensilio se caracteriza por los siguientes elementos: acople a la máquina de ensayos, eje superior, dos brazos dispuestos de modo similar a los de un compás, dos ejes inferiores, dos barras en forma de C, cuatro rodamientos, dos guías que contienen carriles para los rodamientos y barras roscadas apropiadas para la unión con las clavijas necesarias en los ensayos de tenacidad a fractura en condiciones de corrosión bajo tensión.Solicitud: 200602554 (09.10.2006)Nº Pub. de Solicitud: ES2322416A1 (19.06.2009)Nº de Patente: ES2322416B1 (05.07.2010