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Scientific and technological production
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    Simulación del proceso de emisión acústica. Generación de ondas elásticas transitorias en un engranaje bajo tensión  Open access

     Cobo Molina, Raul; Rezano Inza, Tomás; Riera Colom, Maria Dolores; Romeral Martinez, Jose Luis
    Reunión de Usuarios de SIMULIA
    Presentation's date: 2012-11-12
    Presentation of work at congresses

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    Con el objetivo de que el funcionamiento de una máquina sea el correcto es imperativo asegurar que existe un buen mantenimiento predictivo. Es conveniente tener un sistema inteligente y dispositivos capaces de detectar fallos en fases tempranas. Los fallos más comunes en máquinas industriales son todos aquellos relacionados con los sistemas de transmisión de potencia. La técnica de emisión acústica (EA) es el último enfoque para detectar e identificar defectos en rodamientos, cajas de cambio y uniones mecánicas. La emisión acústica (EA) es el fenómeno de generación de ondas elásticas transitorias en materiales bajo tensión. Cuando el material está sometido a un cierto nivel de tensión, una liberación rápida de energía de deformación tiene lugar en forma de ondas elásticas, las cuales pueden ser detectadas mediante transductores colocados en la pieza en cuestión. El objetivo de este trabajo es proporcionar una caracterización de las ondas elásticas que emanan de grietas localizadas entre el flanco y el valle de un engranaje. Las señales han sido registradas usando transductores colocados en la superficie del engranaje (a media distancia entre el eje y los dientes). El método de los elementos finitos ha sido utilizado para simular las ondas elásticas emitidas durante el crecimiento de las grietas. El modelo de simulación está basado en suposiciones elásticas y se ha llevado a cabo mediante Abaqus. Estos resultados han sido comparados con los resultados experimentales.

    In order to have a machine that functions well it is imperative to ensure that there is a good predictive maintenance. An intelligent system and devices able to detect the fault in its early stage is then convenient. The most common failures in industrial machines are those related to the power transmission systems. Acoustic Emission (AE) is the latest approach in detecting and identifying faults in bearings, gearboxes and mechanical couplings. Acoustic Emission (AE) is the phenomenon of transient elastic wave generation in materials under stress. When the material is subjected to stress at a certain level, a rapid release of strain energy takes place in the form of an elastic wave which can be detected by transducers placed on it. The objective of this work is to provide a characterization of elastic waves emanating from cracks located between the flank and the valley of a gear. The signals have been recorded using transducers attached to the surface of the gear (midway between the shaft and the teeth). FE modeling has been used to simulate the elastic waves emitted from fatigue crack growth. The model is based on linear elasticity assumptions and undertaken using Abaqus. These results have been compared with the experimental ones.

  • Young's modulus variation during unloading for a wide range of AHSS steel sheets

     Cobo Molina, Raul; Hernandez Rossi, Ricardo; Benito Paramo, Jose Antonio; Riera Colom, Maria Dolores
    International Deep Drawing Research Group
    Presentation's date: 2011-06-07
    Presentation of work at congresses

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  • Predicción del springback en el conformado asistido por láser de chapas de acero DP800 mediante simulación con Abaqus

     Cobo Molina, Raul; Brígido Belmonte, Albert; Benito Paramo, Jose Antonio; Romero, Pablo; Otero, Nerea; Riera Colom, Maria Dolores
    Congreso Nacional de Tratamientos Térmicos y de Superficie
    Presentation's date: 2010-10
    Presentation of work at congresses

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  • Simulación del proceso de generación de ultrasonidos mediante láser: detección, posicionamiento y medición de grietas o ranuras superficiales en régimen termolástico

     Cobo Molina, Raul; Riera Colom, Maria Dolores
    Reunión Nacional de Usuarios de SIMULIA
    Presentation's date: 2010-11
    Presentation of work at congresses

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    Analysis of the decrease of the apparent young's modulus of advanced high strength steels and its effect in bending simulations  Open access

     Cobo Molina, Raul; Pla, M.; Hernandez Rossi, Ricardo; Benito Paramo, Jose Antonio
    International Deep Drawing Research Group Conference
    Presentation's date: 2009-06-01
    Presentation of work at congresses

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    In this paper the evolution of the Young’s Modulus (E) during unloading with plastic deformation has been studied for different Dual-Phase AHSS from DP780 to DP1400. During unloading, all the DP steels studied showed the presence of microplasticity so an Apparent Young’s Modulus (EA) has been defined. Although that in all cases EA decreased with a non-linear behavior as the plastic strain was increased, it has been observed that the final percentage of decrease seems to be related to the microstructure of DP steels. As the ferrite content increased as in the lower strength DP steels, the reduction of EA is larger, reaching a 21%. The introduction of the variation of the elastic response during unloading in the simulation of a bending operation has allowed obtaining an improvement of the accuracy in springback prediction in all the DP steels studied. For the low strength DP steels the final shape obtained by simulation is in fact the same than the real one. As the strength of steel is increased, the accuracy is less, especially in the DP 1400 steel, in which differences in bending angle higher than a 15% are still found.

  • Study of the influence of the decrease of the apparent young¿s modulus during unloading in the springback prediction

     Cobo Molina, Raul; Hernandez Rossi, Ricardo; Benito Paramo, Jose Antonio; Casellas Padro, Daniel; Riera Colom, Maria Dolores
    International Deep Drawing Research Group
    Presentation's date: 2008-06-16
    Presentation of work at congresses

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