Examinando por Autor "Molina-Aldareguia, Jon"
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Ítem Analysis of the damage evolution in steel specimens under tension by means of XRTC(2017-03) Suárez-Guerra, Fernando; Gálvez-Ruíz, Jaime Carlos; Cendón, David Ángel; Atienza, José Miguel; Sket, Federico; Molina-Aldareguia, JonWhen a steel specimen is tested under tension, damage usually develops evenly all along the specimen, finally necking and leading to the typical cup-cone fracture surface. Nevertheless, some steels present an unusual fracture pattern consisting on a plane fracture surface with a dark region in the centre of the fracture zone. In this contribution, the authors analyse the evolution of the internal damage by using X-ray computed tomography (XRCT) on 3mm-diametre specimens of two steels. The specimens are tested in subsequent loading steps, after each of which it is unloaded and analysed with XRCT. This procedure helps to identify the evolution of damage developed inside each specimen at predefined strain levels. XRCT reveals a very high initial porosity in the material with the cup-cone fracture pattern and a very low initial porosity in the other. In the latter, fracture is triggered by a concentrated internal damage that can be seen as an internal notch which produces a stress concentration that leads to the eventual failure.Ítem Damage evolution in pearlitic steel specimens under tension by means of X-ray computed tomography(2015-06) Suárez-Guerra, Fernando; Gálvez-Ruíz, Jaime Carlos; Atienza, José Miguel; Cendón, David Ángel; Elices, Manuel; Sket, Federico; Molina-Aldareguia, JonIn this contribution, the authors analyse the evolution of the internal damage by using X-ray computed tomography on a 3mm-diametre specimen. The specimen is tested in consecutive loading steps, after each of which it is unloaded and analysed with a X-ray tomograph. This procedure helps to identify the evolution of damage developed inside the specimen at predefined strain levels. Finally, these results are compared with the numerical results provided by the GTN model.Ítem The Evolution of Internal Damage Identified by Means of X-ray Computed Tomography in Two Steels and the Ensuing Relation with Gurson’s Numerical Modelling(MDPI, 2019-03) Suárez-Guerra, Fernando; Sket, Federico; Gálvez-Ruíz, Jaime Carlos; Cendón, David Ángel; Atienza, José Miguel; Molina-Aldareguia, JonThis paper analyzes the evolution of the internal damage in two types of steel that show different fracture behaviors, with one of them being the initial material used for manufacturing prestressing steel wires, and the other one being a standard steel used in reinforced concrete structures. The first of them shows a flat fracture surface perpendicular to the loading direction while the second one shows the typical cup-cone surface. 3 mm-diameter cylindrical specimens are tested with a tensile test carried out in several loading steps and, after each of them, unloaded and analyzed with X-ray tomography, which allows detection of internal damage throughout the tensile test. In the steel used for reinforcement, damage is developed progressively in the whole specimen, as predicted by Gurson-type models, while in the steel used for manufacturing prestressing steel-wire, damage is developed only in the very last part of the test. In addition to the experimental study, a numerical analysis is carried out by means of the finite element method by using a Gurson model to reproduce the material behavior.