FRRA - Investigación y Producción Científica

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Start date: 2010End date: 2017

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    Estudio comparativo de la capacidad portante de pilotes excavados con lodo bentonítico en la ciudad de Rafaela vía método semi- empírico
    (2010) Begliardo, Hugo; Navarro, Viviana; Salusso, Claudio
    El incremento del nivel freático en la ciudad de Rafaela, operado en las dos últimas décadas del siglo XX, provocó daños por asientos diferenciales en edificios pesados cimentados superficialmente, obligando a recalzarlos y generando un cambio de visión en el modo de fundar en la ciudad. A partir de ello, se tornó obligatoria por ordenanza municipal la realización de estudios de suelos en nuevos edificios de mediano a gran porte derivando, generalmente, en la necesidad de ejecutar fundaciones profundas. Para el respectivo diseño se recurrió a métodos analíticos para la determinación de la capacidad portante de pilotes; en otros, a semi-empíricos basados en la experiencia brasilera sobre el tema. Desde la perspectiva del tiempo transcurrido, se pudo corroborar que la evaluación del desempeño de fundaciones efectuadas, tanto con estos últimos como con los primeros, fue satisfactoria, infiriéndose que debían presentarse coincidencias entre ambos, factores de seguridad conservadores u otras razones frente al dispar enfoque con que eran abordados. El objetivo del trabajo fue comparar los resultados de catorce estudios de suelos, desarrollados en un período de veinte años, de siete autores diferentes, basados en métodos analíticos y semi-empíricos, cotejándolos con la aplicación a ellos del método semi-empírico de “Decourt-Quaresma extendido” de 1996 y extraer conclusiones sobre sus aptitudes. Como base de comparación del estudio se tomaron los resultados de un pilote de 40 cm de diámetro, excavado con el empleo de lodo bentonítico.
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    Study of Residual Stress Relaxation Mechanics Using a Micro-indent Method
    (2016-12-05) Díaz, F.V; Mammana, C. A.; Guidobono, A. P. M.
    The aim of this study is to show the feasibility and accuracy of a micro-indent method to comprehensively evaluate the relaxation mechanics of residual stress in specimens of rolled aluminium alloy. This micro-indent method was adapted to implement four annealing treatments. The residual displacements were measured using a high-accuracy measuring machine, which enables to decrease the absolute error down to ±300 nm. This study presents an innovative data analysis using Mohr's circles, which allowed to study all directions of the inplane residual stress for different relaxation times. The results revealed that the relaxation process finishes when the residual stress relief is completed in some preferential directions and then, a brief stress recovery phase begins.
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    Evaluation of Residual Stresses Induced by Face Milling Using a Method of Micro-indents
    (2017-02-17) Díaz, F.V; Mammana, C. A.; Guidobono, A. P. M.
    The aim of this study is to determine and evaluate residual stresses induced by face milling in different zones, which are associated with asymmetries in orientation of cutting edge. In this study, a micro-indent method is used to determine these stresses, which were induced in samples of AA 7075-T6 aluminum alloy. The residual displacements were measured, with high accuracy, using a universal measuring machine. This study includes a thorough data analysis using Mohr's circles, which enabled to assess the stress states in all in-plane directions. The results obtained in samples subjected to different combinations of process parameters showed the introduction of compressive normal components for all directions of each zone evaluated. From the high sensitivity of the microindent method used, it was possible to detect smaller differences generated between the levels reaching the stress components in the cutting zones evaluated. Furthermore, these differences were similar for all evaluated directions when the highest feed rate was selected. This significant fact, finally, would reveal equivalent differences between asymmetrical zones, regarding the combination of local plastic deformation and heat reaching the milled surface, for all in-plane directions.
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    Analysis of Residual Stresses in High Speed Milled Aluminum Alloys
    (2017-03-15) Vottero, S.; Díaz, F.V.; Mammana, C.A; Guidobono, A. P. M.
    The purpose of this study is to evaluate, from high speed machining tests, the behavior of the residual stresses induced in samples of AA 6082-T6 and AA 7075-T6 aluminum alloys. This study includes an exhaustive analysis of residual stress anisotropy from diameters of Mohr's circles. The combination of process parameters was modified in order to evaluate the stress changes introduced in different zones of the surfaces generated. A method of micro-indents, which includes the adaptation of a universal measuring machine, was used to determine, with high accuracy, the normal components of residual stress in several directions. The obtained results reveal that although, in the alloy 7075-T6, the normal components are lower, in the alloy 6082-T6, these normal components tend to be grouped into smaller intervals and also, to show a more homogeneous directional behavior when the cutting conditions are more severe.