DIMM-Artículos
URI permanente para esta colecciónhttps://hdl.handle.net/10953/243
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Examinando DIMM-Artículos por Materia "691.714"
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Ítem Distinct Fracture Patterns in Construction Steels for Reinforced Concrete under Quasistatic Loading— A Review(MDPI, 2018-03) Suárez-Guerra, Fernando; Gálvez-Ruíz, Jaime Carlos; Cendón, David Ángel; Atienza, José MiguelSteel is one of the most widely used materials in construction. Nucleation growth and coalescence theory is usually employed to explain the fracture process in ductile materials, such as many metals. The typical cup–cone fracture pattern has been extensively studied in the past, giving rise to numerical models able to reproduce this pattern. Nevertheless, some steels, such as the eutectoid steel used for manufacturing prestressing wires, does not show this specific shape but a flat surface with a dark region in the centre of the fracture area. Recent studies have deepened the knowledge on these distinct fracture patterns, shedding light on some aspects that help to understand how damage begins and propagates in each case. The numerical modelling of both fracture patterns have also been discussed and reproduced with different approaches. This work reviews the main recent advances in the knowledge on this subject, particularly focusing on the experimental work carried out by the authors.Ítem Fracture of eutectoid steel bars under tensile loading: Experimental results and numerical simulation Author links open overlay panel(Elsevier, 2016-06) Suárez-Guerra, Fernando; Gálvez-Ruíz, Jaime Carlos; Cendón, David Ángel; Atienza, José MiguelConstruction steel bars tested under tension usually show a cup-cone fracture pattern. Nevertheless, some steels, such as the eutectoid one used for manufacturing prestressing steel wires, show a different pattern: a flat fracture surface with a dark region inside. This paper presents experimental work performed to identify the fracture mechanisms that trigger this particular flat fracture pattern and numerical simulations where it is reproduced numerically. The experimental tests are carried out on cylindrical specimens of three diameters, 3, 6 and 9 mm, subjected to tension. In order to analyse the fracture mechanism, numerical simulations are performed by using the finite element method and the cohesive zone approach. To that end, a cohesive interface element with mechanical properties that depend on the stress triaxiality is presented and assessed. This approach provides reasonably good agreement with the experimental results. In addition, when compared with other popular models such as the GTN model, it presents certain advantages since it requires a smaller number of parameters to be defined.Ítem Study of the last part of the stress-deformation curve of construction steels with distinct fracture patterns(Elsevier, 2016-10) Suárez-Guerra, Fernando; Gálvez-Ruíz, Jaime Carlos; Cendón, David Ángel; Atienza, José MiguelThe principal mechanical characteristics of construction steels are obtained by tensile testing. Nevertheless, the standards neglect the behaviour of steel beyond the maximum load point and do not define parameters related to the part of the stress-deformation curve that lies between the maximum load point and failure. The necking process that begins when the maximum load is reached makes it somewhat difficult to study the material behaviour beyond that point. However, the ductility of steel is highly affected by this last part of the load-deformation curve. For such a reason, and especially since structural safety is directly related to ductility, a deeper knowledge of this may help in designing safer structures. In this paper, this part of the load-deformation curve is analysed in two construction steels that exhibit distinct fracture patterns: one shows the typical cup-cone fracture surface, while the other shows a flat fracture surface with a dark region inside. An experimental campaign has been carried out with cylindrical specimens of contrasting diameters: 3 mm, 6 mm and 9 mm for each material. The use of a digital image correlation system is shown to be extremely useful in studying the behaviour of steel beyond the maximum load point, with an innovative procedure for identifying the growth of the internal damage that leads to failure in a specimen being developed.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.