Recursos de colección

Archivo Digital UPM (109.492 recursos)

This is an institutional repository providing access to the research output of the institution. Primarily contains thesis.

Materia = Materiales

Mostrando recursos 1 - 20 de 818

  1. Revisión y desarrollo de modelos de clasificación del corcho en plancha

    Benito Lázaro, David
    La calidad de las planchas de corcho, entendida como su aptitud para la fabricación de tapones de corcho natural, determina la clase comercial de las mismas y, por tanto, su valor económico. Esta clasificación, llevada a cabo tradicionalmente en la industria preparadora por el escogedor, depende en gran medida de las anomalías presentes en la plancha. Con el objetivo de conocer qué variables entran en juego en la clasificación y cuál es el peso de cada una de ellas, se han realizado diferentes estudios. García de Ceca (2001) propone modelos de clasificación de piezas de corcho en plancha de...

  2. New designs of the ceramic bricks of horizontal hexagonal hollow

    Corbella Ribes, David; Fernández Martínez, Francisco; Hernandez Olivares, Francisco; Armisen Bobo, Pedro
    This article is intended to state that Technical Drawing is a multiple tool of expression and communication essential to develop inquiry processes, the scientifically basis and comprehension of drawings and technological designs that can be manufactured. We demonstrate graphically and analytically that spatial vision and graphic thinking allow us to identify graphically real life problems, develop proposals of solutions to be analysed from different points of view, plan and develop the project, provide information needed to make decisions on objects and technological processes. From the knowledge of Technical Drawing and CAD tools we have developed graphic analyses to improve and...

  3. Ladrillo cerámico con huecos hexagonales.

    Fernández Martínez, Francisco; Hernandez Olivares, Francisco; Corbella Ribes, David
    Ladrillo cerámico con huecos hexagonales. La invención consiste en un ladrillo cerámico con huecos hexagonales a lo largo de su dirección longitudinal. Resuelve el problema de la transmisión de ruido aéreo que presentan los ladrillos cerámicos con hueco cuadrado o rectangular. La intensidad del sonido transmitido en sólidos decrece con el aumento de camino recorrido. Por ello, la sustitución de las paredes perpendiculares que definen los huecos cuadrados o rectangulares, por las que definen los huecos hexagonales representa un mayor recorrido y una absorción mayor de ruido. El espesor del ladrillo puede variar según contenga una o más filas de...

  4. Principales maderas de frondosas de España. Características, tecnología y aplicaciones

    Vignote Peña, Santiago
    Se describen las características de las principales maderas españolas, eso no quiere decir que las especies descritas procedan de masas naturales, sino que en muchos casos esas masas forestales están pobladas con especies introducidas. La descripción incluye el nombre científico, sinonimias, nombres vulgares, su distribución en el mundo y en España, la descripción del fuste y de las trozas, con sus defectos más característicos, la descripción de la madera macro y microscópicamente, sus características anatómicas, físicas, mecánicas, resistentes, durables y químicas. También se incluye sus aspectos tecnológicos, en el sentido de indicar que aspectos deben considerarse a la hora de trabajar estas...

  5. Effect of strain and magnetic field on the critical current and electric resistance of the joints between HTS coated conductors

    Konstantopoulou, Konstantina; Serazin, M.; Lloberas, J.; Granados, X.; Sanmarti, M.; Obradors, X.; Pastor Caño, Jose Ignacio
    Engineering of devices and systems such as magnets, fault current limiters or cables, based on High Temperature Superconducting wires requires a deep characterization of the possible degradation of their properties by handling at room temperature as well as during the service life thus establishing the limits for building up functional devices and systems. In the present work we report our study regarding the mechanical behavior of spliced joints between commercial HTS coated conductors based on YBCO at room temperature and service temperature, 77 K. Tensile tests under axial stress and the evolution of the critical current and the electric resistance of the joints have been measured. The complete...

  6. Effect of strain and magnetic field on the critical current and electric resistance of the joints between HTS coated conductors

    Konstantopoulou, Konstantina; Serazin, M.; Lloberas, J.; Granados, X.; Sanmarti, M.; Obradors, X.; Pastor Caño, Jose Ignacio
    Engineering of devices and systems such as magnets, fault current limiters or cables, based on High Temperature Superconducting wires requires a deep characterization of the possible degradation of their properties by handling at room temperature as well as during the service life thus establishing the limits for building up functional devices and systems. In the present work we report our study regarding the mechanical behavior of spliced joints between commercial HTS coated conductors based on YBCO at room temperature and service temperature, 77 K. Tensile tests under axial stress and the evolution of the critical current and the electric resistance of the joints have been measured. The complete...

  7. Principales maderas de coníferas en España características, tecnología y aplicaciones

    Vignote Peña, Santiago
    continuación se describen las características de las principales maderas españolas, eso no quiere decir que las especies descritas procedan de masas naturales, sino que en muchos casos esas masas forestales están pobladas con especies introducidas. La descripción incluye el nombre científico, sinonimias, nombres vulgares, su distribución en el mundo y en España, la descripción del fuste y de las trozas, con sus defectos más característicos, la descripción de la madera macro y microscópicamente, sus características anatómicas, físicas, mecánicas, resistentes, durables y químicas. También se incluye sus aspectos tecnológicos, en el sentido de indicar que aspectos deben considerarse a la hora de trabajar...

  8. Mechanical behavior of alkali-cement as function of the temperature.

    Martin Sanz, Antonia; Ajejas, F.; Moreno, S.; Pastor Caño, Jose Ignacio; Palomo, Angel; Fernandez Jimenez, Ana
    This investigation reports on a comparative study of the mechanical behavior at different temperatures of three different alkali-activated fly ash pastes chemically activated using sodium silicate. A control Portland cement (OPC) was used as a reference. In an attempt to simulate the conditions prevailing in the event of accidental fire, post-thermal mechanical tests were performed to determine the residual strength. It has therefore been established that FA based cements can be fabricated for construction purposes and these materials have great potential for fire resistance applications.

  9. Damage mechanisms of 3D woven hybrid composites in tension. Testing, inspection and simulation

    Muñoz, R.; González Martínez, Carlos Daniel; Llorca Martinez, Francisco Javier
    Delamination reduces the strenght of the composites, mainly in compression. Several methods exist to overcome this problem, but they are either not feasible for large scale production or too expensive. 3D composites are a promising solution.

  10. Latent hardening size effect in small-scale plasticity

    Bardella, Lorenzo; Segurado Escudero, Javier; Panteghini, Andrea; Llorca Martinez, Francisco Javier
    We aim at understanding the multislip behaviour of metals subject to irreversible deformations at small-scales. By focusing on the simple shear of a constrained single-crystal strip, we show that discrete Dislocation Dynamics (DD) simulations predict a strong latent hardening size effect, with smaller being stronger in the range [1.5 µm, 6 µm] for the strip height. We attempt to represent the DD pseudo-experimental results by developing a flow theory of Strain Gradient Crystal Plasticity (SGCP), involving both energetic and dissipative higher-order terms and, as a main novelty, a strain gradient extension of the conventional latent hardening. In order to discuss...

  11. Simulation of the deformation of polycrystalline nanostructured Ti by computational homogenization

    Segurado Escudero, Javier; Llorca Martinez, Francisco Javier
    Computational homogenization by means of the finite element analysis of a representative volume element of the microstructure is used to simulate the deformation of nanostructured Ti. The behavior of each grain is taken into account using a single crystal elasto-viscoplastic model which includes the microscopic mechanisms of plastic deformation by slip along basal, prismatic and pyramidal systems. Two different representations of the polycrystal were used. Each grain was modeled with one cubic finite element in the first one while many cubic elements were used to represent each grain in the second one, leading to a model which includes the effect...

  12. Grain size gradient length scale in ballistic properties optimization of functionally graded nanocrystalline steel plates

    Jérusalem, Antoine; Dickson, William; Pérez Martín, Maria Jesus; Dao, Ming; Lu, Jian; Galvez Diaz-Rubio, Francisco
    The last few years have highlighted the existence of two relevant length scales in the quest to ultrahigh-strength polycrystalline metals. Whereas the microstructural length scale – e.g. grain or twin size – has mainly be linked to the well-established Hall–Petch relationship, the sample length scale – e.g. nanopillar size – has also proven to be at least as relevant, especially in microscale structures. In this letter, a series of ballistic tests on functionally graded nanocrystalline plates are used as a basis for the justification of a “grain size gradient length scale” as an additional ballistic properties optimization parameter.

  13. Study of the effect of four warm mix asphalt additives on bitumen modified with 15% crumb rubber

    Rodríguez Alloza, Ana María; Gallego Medina, Juan; Pérez Díaz, Juan Ignacio
    Due to a growing concern over global warming, the bituminous mixture industry is making a constant effort to diminish its emissions by reducing manufacturing and installation temperatures without compromising the mechanical properties of the bituminous mixtures. The use of mixtures with tyre rubber has demonstrated that these mixtures can be economical and ecological and that they improve the behaviour of the pavements. However, bituminous mixtures with a high rubber content present one major drawback: they require higher mixing and installation temperatures due to the elevated viscosity caused by the high rubber content and thus they produce larger amounts of greenhouse...

  14. An experimental and numerical study of the pattern of cracking of concrete due to steel reinforcement corrosion

    Sanz Merino, Beatriz; Planas Rosselló, Jaime; Sancho Aznal, José María
    In this work, cracking of concrete due to steel reinforcement corrosion is experimentally and numerically studied. The tests combined accelerated corrosion—to generate the cracks—with impregnation under vacuum with resin containing fluorescein—to enhance their visibility under ultraviolet light. In parallel, a model—called expansive joint element—was developed to simulate the expansion of the oxide and finite elements with an embedded adaptable cohesive crack were used to describe concrete cracking. The results show that a good agreement exists between the experimental and numerical crack patterns, which constitutes promising progress towards a comprehensive understanding of corrosion-induced cracking in reinforced concrete.

  15. High temperature micropillar compression of Al/SiC nanolaminates

    Lotfian, S.; Rodriguez, M.; Yazzie, K.E.; Chawla, N.; Llorca Martinez, Francisco Javier; Molina Aldareguía, Jon M.
    The effect of the temperature on the compressive stress–strain behavior of Al/SiC nanoscale multilayers was studied by means of micropillar compression tests at 23 °C and 100 °C. The multilayers (composed of alternating layers of 60 nm in thickness of nanocrystalline Al and amorphous SiC) showed a very large hardening rate at 23 °C, which led to a flow stress of 3.1 ± 0.2 GPa at 8% strain. However, the flow stress (and the hardening rate) was reduced by 50% at 100 °C. Plastic deformation of the Al layers was the dominant deformation mechanism at both temperatures, but the Al...

  16. Aplicación de los sistemas de separación hidráulica y magnética al reciclado de los residuos de construcción y demolición

    Rodríguez-Avello Sanz, Ángel; Gómez-Limón, Dulce; Peña Narciso, Christian; Fueyo, Luis
    En el presente estudio se analizan las últimas técnicas aplicadas al reciclaje de los residuos de construcción y demolición (RCD), en los que además de los sistemas clásicos de estrio manual y mecánico, trituración y clasificación granulométrica se introducen los equipos de separación hidráulica (clasificadores de banda y tornillos sin fin) y los de pulsación por corriente turbulenta de acción diferencial (Jig). De igual forma los áridos reciclados ganan en calidad cuando se someten a procesos de separación magnética en los cuales las fracciones cerámicas (ladrillos) responden de forma positiva teniendo en cuenta los componentes férricos de las arcillas en...

  17. Optimization of curing cycle in carbon fiber-reinforced laminates: Void distribution and mechanical properties

    Hernández, S.; Sket, Federico; González Martínez, Carlos Daniel; Llorca Martinez, Francisco Javier
    A strategy is presented to optimize out-of-autoclave processing of quasi-isotropic carbon fiber-reinforced laminates. Square panels of 4.6 mm nominal thickness with very low porosity ð6 0:2%Þ were manufactured by compression molding at low pressure (0.2 MPa) by careful design of the temperature cycle to maximize the processing window. The mechanisms of void migration during processing were ascertained by means of X-ray microtomography and the effect of ply clustering on porosity and on void shape was explained. Finally, the effect of porosity and ply clustering on the compressive strength before and after impact was studied.

  18. Superplastic deformation of directionally solidified nanofibrillar Al2O3-Y3Al5O12-ZrO2 eutectics

    Pastor Caño, Jose Ignacio; Martin Sanz, Antonia; Molina Aldareguía, Jon M.; Llorca Martinez, Francisco Javier; Oliete Terraz, Patricia Beatriz; Larrea, Angel; Peña Torre, José Ignacio; Orera, V.M.; Arenal, Raúl
    Nanofibrillar Al2O3–Y3Al5O12–ZrO2 eutectic rods were manufactured by directional solidification from the melt at high growth rates in an inert atmosphere using the laser-heated floating zone method. Under conditions of cooperative growth, the ternary eutectic presented a homogeneous microstructure, formed by bundles of single-crystal c-oriented Al2O3 and Y3Al5O12 (YAG) whiskers of ≈100 nm in width with smaller Y2O3-doped ZrO2 (YSZ) whiskers between them. Owing to the anisotropic fibrillar microstructure, Al2O3–YAG–YSZ ternary eutectics present high strength and toughness at ambient temperature while they exhibit superplastic behavior at 1600 K and above. Careful examination of the deformed samples by transmission electron microscopy did...

  19. Mechanical behavior of tungsten-vanadium-lanthana alloys as function of temperature

    Palacios García, Teresa; Pastor Caño, Jose Ignacio; Aguirre Cebrian, Maria Vega; Martin Sanz, Antonia; Monge, M. A.; Muñoz, A.; Pareja, R.
    The mechanical behavior of three tungsten (W) alloys with vanadium (V) and lanthana (La2O3) additions (W–4%V, W–1%La2O3, W–4%V–1%La2O3) processed by hot isostatic pressing (HIP) have been compared with pure-W to analyze the influence of the dopants. Mechanical characterization was performed by three point bending (TPB) tests in an oxidizing air atmosphere and temperature range between 77 (immersion tests in liquid nitrogen) and 1273 K, through which the fracture toughness, flexural strength, and yield strength as function of temperature were obtained. Results show that the V and La2O3 additions improve the mechanical properties and oxidation behavior, respectively. Furthermore, a synergistic effect of...

  20. An embedded cohesive crack model for finite element analysis of quasi-brittle materials

    Gálvez Ruíz, Jaime; Planas Rosselló, Jaime; Sancho Aznal, José María; Reyes Pozo, Encarnación; Cendón Franco, David Angel; Casati Calzada, María Jesús
    This paper presents a numerical implementation of the cohesive crack model for the anal-ysis of quasibrittle materials based on the strong discontinuity approach in the framework of the finite element method. A simple central force model is used for the stress versus crack opening curve. The additional degrees of freedom defining the crack opening are determined at the crack level, thus avoiding the need for performing a static condensation at the element level. The need for a tracking algorithm is avoided by using a consistent pro-cedure for the selection of the separated nodes. Such a model is then implemented into...

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