Artículos (Mecánica de Medios Continuos y Teoría de Estructuras)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/11397

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A semi-analytical matrix formalism for stress singularities in anisotropic multi-material corners with frictional boundary and interface conditions
(Elsevier, 2024-02) Herrera Garrido, María Ángeles; Mantic, Vladislav; Barroso Caro, Alberto; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia, Innovación y Universidades (MCIU). España; European Commision. Fondo Europeo de Desarrollo Regional; Consejería de Transformación Económica, Industria, Conocimiento y Universidades, Junta de Andalucía; Universidad de Sevilla. TEP131: Elasticidad y Resistencia de Materiales
A new general semi-analytic procedure for the characterisation of singular asymptotic elastic states in the vicinity of the apex of linearly elastic anisotropic multi-material corners, including frictional contact, is developed and tested. The corners can consist of any finite number of homogeneous wedges defined by polar sectors. The variability of configurations covered is enormous as frictional contact can be considered on one or more outer boundary surfaces or interfaces, in addition to a large variety of homogeneous boundary conditions and perfect bonding or frictionless sliding interface conditions between wedges in the corner. The Coulomb rate-independent and dry frictional contact law is assumed. One of the novelties is that, in addition to the singularity exponent 𝜆, the angle 𝜔 of the friction tangential stress vector on each frictional contact surface is an a priory unknown to be determined by solving a nonlinear corner eigensystem. The procedure, which considers power-law stress singularities, is based on the Stroh formalism of anisotropic elasticity, assuming generalised plane strain (2.5D) conditions, and on the semi-analytic matrix formalism for wedge transfer-matrices and boundary and interface condition matrices. This makes it, firstly, very suitable for computational implementations, secondly, very efficient especially in cases with several perfectly bonded homogeneous wedges, and, thirdly, very accurate due to its fully semi-analytic nature. The code developed is tested by solving a large variety of examples, comparing the present results with those obtained by solving closed-form corner-eigenequations deduced by previous authors for specific useful practical configurations, confirming the extremely high accuracy of the present code in the computation of 𝜆 and 𝜔. The differences observed in some cases with anisotropic materials are explained by the fact that some of the previous authors did not take the true 3D Coulomb friction law into account.
Analysis of the mechanical and fracture behavior of heated ultra-high-performance fiber-reinforced concrete by X-ray computed tomography
(Elsevier, 2019-05) Ríos Jiménez, José David; Cifuentes-Bulté, Héctor; Leiva Fernández, Carlos; Seitl, Stanislav; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental; Universidad de Sevilla. TEP972: Mecánica de Materiales y Estructuras
This work analyzes the effects of temperature (300 °C) on mechanical and fracture behavior of an ultra-high-performance steel-fiber-reinforced concrete. The deterioration of the pore structure due to thermal damage of the fiber-reinforced concrete and its un-reinforced matrix was analyzed by X-ray computed tomography. Complementarily, a thermogravimetric analysis was performed to relate the observed phase changes, due to dehydration and decomposition, with the deterioration of pore structure. Additionally, an analysis of their mechanical and fracture properties was also done at room temperature and 300 °C. Finally, a connection between the damage within the concrete matrix and its corresponding mechanical behavior was established. From the results, it has been ascertained that the propagation of thermal damage within the matrix affects the mechanical and fracture behavior in different ways depending on the pore-size. The presence of fibers modifies the pore structure and consequently the evolution of the thermal damage in the ultra-high-performance concrete, inferring its mechanical and fracture behavior.
Experimental observations of fatigue damage in cross-ply laminates using carbon/epoxy ultra-thin plies
(Elsevier, 2023-02-15) Sánchez-Carmona, Serafín; Correa Montoto, Elena; Barroso Caro, Alberto; París Carballo, Federico; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Universidad de Sevilla. TEP131: Elasticidad y Resistencia de Materiales
The damage mechanisms of cross-ply laminates under fatigue loading have been deeply studied during last years. In the case of quasi-static loads the so-called scale effect has recently acquired renewed importance after the appearance of ultra-thin plies. In this work, the experimental observation of the onset of transverse damage and its progression in two different cross-ply laminates under tension–tension cyclic loading is performed. First, a [04/903/04] laminate made of plies with conventional thickness (150 g/m2) is analysed. After looking for the expected fatigue damage mechanisms in this case, a [04/90/04] laminate with a single ultra-thin 90⁰ ply (30 g/m2) is studied. All specimens have been carefully examined by means of an optical microscope, detecting the expected damage mechanisms for [04/903/04] and non-conventional types of damages for [04/90/04]. The change of fatigue damage mechanisms for cross-ply laminates involving an ultra-thin 90⁰ ply is microscopically detailed, meaning the evidence of the delay of transverse damage onset in the 90° layer under cyclic loading. This evidence shows the existence of a scale effect concerning the appearance of the fatigue damage mechanisms.

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