Artículos (Mecánica de Medios Continuos y Teoría de Estructuras)

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

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Influence of main operating conditions on contact wire wear of rigid catenary lines
(Elsevier, 2024-08) Simarro Vega, Montserrat; Postigo Pozo, Sergio; Casanueva, Carlos; Rodríguez de Tembleque Solano, Luis; Castillo Aguilar, Juan Jesús; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Junta de Andalucía; Universidad de Málaga; Universidad de Sevilla. TEP245: Ingeniería de las Estructuras
A validated overhead conductor rail and a well-known wear model have been programmed to perform closer-to-reality simulations. Reliable wear rate estimates for two configurations of overhead conductor rails and three models of pantographs at different speeds and supply currents have been obtained. Results show that wear decreases with increasing speed at high currents and when the distances between supports are uniform. In addition, the use of different types of pantographs in the same facility has a positive effect in terms of wear reduction. Consequently, an adequate selection of the operating conditions contributes to reducing the wear rate.
Force-mediated recruitment and reprogramming of healthy endothelial cells drive vascular lesion growth
(Nature Research, 2024-10-06) Shapeti, Apeksha; Barrasa Fano, Jorge; Abdel Fattah, Abdel Rahman; De Jong, Janne; Sanz Herrera, José Antonio; Pezet, Mylène; Assou, Said; De Vet, Emilie; Elahi, Seyed Ali; Ranga, Adrian; Faurobert, Eva; Van Oosterwyck, Hans; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Research Foundation Flanders (FWO); Universidad de Sevilla. TEP245: Ingeniería de las Estructuras
Force-driven cellular interactions are crucial for cancer cell invasion but remain underexplored in vascular abnormalities. Cerebral cavernous malformations (CCM), a vascular abnormality characterized by leaky vessels, involves CCM mutant cells recruiting wild-type endothelial cells to form and expand mosaic lesions. The mechanisms behind this recruitment remain poorly understood. Here, we use an in-vitro model of angiogenic invasion with traction force microscopy to reveal that hyper-angiogenic Ccm2-silenced endothelial cells enhance angiogenic invasion of neighboring wild-type cells through force and extracellular matrix-guided mechanisms. We demonstrate that mechanically hyperactive CCM2-silenced tips guide wild-type cells by transmitting pulling forces and by creating paths in the matrix, in a ROCKs-dependent manner. This is associated with reinforcement of β1 integrin and actin cytoskeleton in wild-type cells. Further, wild-type cells are reprogrammed into stalk cells and activate matrisome and DNA replication programs, thereby initiating proliferation. Our findings reveal how CCM2 mutants hijack wild-type cell functions to fuel lesion growth, providing insight into the etiology of vascular malformations. By integrating biophysical and molecular techniques, we offer tools for studying cell mechanics in tissue heterogeneity and disease progression.
Optimisation of steel bars to repair and reinforce masonries
(Elsevier, 2024) Rodríguez-Mayorga, Esperanza; Fernández Ancio, Fernando; Hortigón Fuentes, Beatriz; Universidad de Sevilla. Departamento de Estructuras de Edificación e Ingeniería del Terreno; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras
The insertion of rebars in masonry is a well-established repair and reinforcing technique. To this end, standard thin rebars are usually employed. In this research, the standard Spanish shape for the stainless-steel wires and rebars is optimised, from the bonding point of view, to work while both highly confined and thinly covered by mortar, thereby reproducing the conditions of rebars between masonry units. A detailed finite-element analysis is employed to choose the best-performing model from of a set of possible designs of 5-mm diameter rebars. The standard shape is set as the starting point for the design of these rebars. In the analyses, the influence of the shape of the ribs, the orientation of the ribs, and the spacing between the ribs on bonding is assessed by finite-element analysis. Finally, a prototype of the best-performing design is manufactured and tested in the laboratory. In order to reproduce more accurately the boundary conditions of rebars once inserted into ma sonries, the standard pull-out test has been adapted with certain modifications expressly designed for this research. The comparison of results with those attained by the standard rebar confirms the improvement achieved by the new design.
Full-scale testing and multiphysics modeling of a reinforced shot-earth concrete vault with self-sensing properties
(Institute of Physics (IOP), 2024-10) D’Alessandro, Antonella; Meoni, Andrea; Rodríguez Romero, Rubén; García-Macías, Enrique; Viviani, Marco; Ubertini, Filippo; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; European Union (UE); Universidad de Perugia; Ministerio de Educación. España
Civil constructions significantly contribute to greenhouse gas emissions and entail extensive energy and resource consumption, leading to a substantial ecological footprint. Research into eco-friendly engineering solutions is therefore currently imperative, particularly to mitigate the impact of concrete technology. Among potential alternatives, shot-earth-concrete, which combines cement and earth as a binder matrix and is applied via spraying, emerges as a promising option. Furthermore, this composite material allows for the incorporation of nano and micro-fillers, thereby providing room for enhancing mechanical properties and providing multifunctional capabilities. This paper investigates the damage detection capabilities of a novel smart shot-earth concrete with carbon microfibers, by investigating the strain sensing performance of a full-scale vault with a span of 4 m, mechanically tested until failure. The material's strain and damage sensing capabilities involve its capacity to produce an electrical response (manifested as a relative change in resistance) corresponding to the applied strain in its uncracked state, as well as to exhibit a significant alteration in electrical resistance upon cracking. A detailed multiphysics numerical (i.e. mechanical and electrical) model is also developed to aid the interpretation of the experimental results. The experimental test was conducted by the application of an increasing vertical load at a quarter of the span, while modelling of the element was carried out by considering a piezoresistive material, with coupled mechanical and electrical constitutive properties, including a new law to reproduce the degradation of the electrical conductivity with tensile cracking. Another notable aspect of the simulation was the consideration of the effects of the electrical conduction through the rebars, which was found critical to accurately reproduce the full-scale electromechanical response of the vault. By correlating the outcomes from external displacement transducers with the self-monitoring features inherent in the proposed material, significant insights were gleaned. The findings indicated that the proposed smart-earth composite, besides being well suited for structural applications, also exhibits a distinctive electromechanical behavior that enables the early detection of damage initiation. The results of the paper represent an important step toward the real application of smart earth-concrete in the construction field, demonstrating the effectiveness and feasibility of full-scale strain and damage monitoring even in the presence of steel reinforcement.
Multiphysics modeling of 3D traction force microscopy with application to cancer cell-induced degradation of the extracellular matrix
(Springer, 2024-07) Apolinar Fernández, Alejandro; Barrasa Fano, Jorge; Van Oosterwyck, Hans; Sanz Herrera, José Antonio; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia e Innovación (MICIN). España; Junta de Andalucía
3D Traction Force Microscopy (3DTFM) constitutes a powerful methodology that enables the computation of realistic forces exerted by cells on the surrounding extracellular matrix (ECM). The ECM is characterized by its highly dynamic structure, which is constantly remodeled in order to regulate most basic cellular functions and processes. Certain pathological processes, such as cancer and metastasis, alter the way the ECM is remodeled. In particular, cancer cells are able to invade its surrounding tissue by the secretion of metalloproteinases that degrade the extracellular matrix to move and migrate towards different tissues, inducing ECM heterogeneity. Typically, 3DTFM studies neglect such heterogeneity and assume homogeneous ECM properties, which can lead to inaccuracies in traction reconstruction. Some studies have implemented ECM degradation models into 3DTFM, but the associated degradation maps are defined in an ad hoc manner. In this paper, we present a novel multiphysics approach to 3DTFM with evolving mechanical properties of the ECM. Our modeling considers a system of partial differential equations based on the mechanisms of activation of diffusive metalloproteinase MMP2 by membrane-bound metalloproteinase MT1-MMP. The obtained ECM density maps in an ECM-mimicking hydrogel are then used to compute the heterogeneous mechanical properties of the hydrogel through a multiscale approach. We perform forward and inverse TFM simulations both accounting for and omitting degradation, and results are compared to ground truth reference solutions in which degradation is considered. The main conclusions resulting from the study are: (i) the inverse methodology yields results that are significantly more accurate than those provided by the forward methodology; (ii) ignoring ECM degradation results in a considerable overestimation of tractions and non negligible errors in all analyzed cases
Homogenization and continuum limit of mechanical metamaterials
(Elsevier, 2024-09) Ariza Moreno, María del Pilar; Conti, Sergio; Ortiz, Michael; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Deutsche Forschungsgemeinschaft / German Research Foundation (DFG); Ministerio de Ciencia e Innovación (MICIN). España; Universidad de Sevilla. TEP972: Mecánica de Materiales y Estructuras
When used in bulk applications, mechanical metamaterials set forth a multiscale problem with many orders of magnitude in scale separation between the micro and macro scales. However, mechanical metamaterials fall outside conventional homogenization theory on account of the flexural, or bending, response of their members, including torsion. We show that homogenization theory, based on calculus of variations and notions of Gamma-convergence, can be extended to account for bending. The resulting homogenized metamaterials exhibit intrinsic generalized elasticity in the continuum limit. We illustrate these properties in specific examples including two-dimensional honeycomb and three-dimensional octet-truss metamaterials.
Regularization techniques and inverse approaches in 3D Traction Force Microscopy
(Elsevier, 2024-12-01) Apolinar Fernández, Alejandro; Blázquez Carmona, Pablo; Ruiz-Mateos Brea, Raquel; Barrasa Fano, Jorge; Van Oosterwyck, Hans; Reina Romo, Esther; Sanz Herrera, José Antonio; Universidad de Sevilla. Departamento de Ingeniería Mecánica y de Fabricación; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Universidad de Sevilla. TEP111: Ingeniería Mecánica; Universidad de Sevilla. TEP245: Ingeniería de las Estructuras
The conception of inverse methods in the context of Traction Force Microscopy (TFM) is influenced by multiple factors, such as nonlinear effects, dimensionality (2D/3D), and regularization/constraints, amongst others. Solving the inverse problem often requires the inversion of a matrix, and the presence of noise in the measured displacements can lead to unrealistic reconstructed tractions. To address this issue, Tikhonov regularization is commonly used, penalizing high norm values of computed tractions. The aim of this study is to compare the performance of different inverse methodologies (including some original variations) in 3D TFM, considering constraint imposition and regularization along the formulation. The different methodologies are numerically elaborated within a novel combined Newton–Raphson/Finite Element Method scheme that provides converged solutions in few iterations. The impact of constraint imposition and regularization in traction reconstruction is evaluated in terms of accuracy, efficiency (CPU time), and inherent characteristics of the methodology. Results show that, applying regularization and constraints (based on the fulfillment of fundamental principles) provides the best traction reconstruction, while simultaneously ensuring an optimum estimate of the maximum traction, at the cost of high CPU time and low efficiency. Moreover, regularization-based methods introduce the challenge of calibrating the regularization parameter, usually done under subjective criteria. On the other hand, non-regularized but constrained methods may represent a nice compromise between accuracy and efficiency, while avoiding pre-processing and calibration of such regularization parameter. It is emphasized the importance of considering not only traction reconstruction quality but also the efficiency and complexity of implementation (intrusiveness) when selecting an appropriate inverse method for TFM analysis.
Quantitative atlas of collagen hydrogels reveals mesenchymal cancer cell traction adaptation to the matrix nanoarchitecture
(Elsevier, 2024-09-01) Blázquez Carmona, Pablo; Ruiz-Mateos Brea, Raquel; Barrasa Fano, Jorge; Shapeti, Apeksha; Martín Alfonso, José Enrique; Domínguez Abascal, Jaime; Van Oosterwyck, Hans; Reina Romo, Esther; Sanz Herrera, José Antonio; Universidad de Sevilla. Departamento de Ingeniería Mecánica y de Fabricación; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Universidad de Sevilla. TEP111: Ingeniería Mecánica; Universidad de Sevilla. TEP245: Ingeniería de las Estructuras
Collagen-based hydrogels are commonly used in mechanobiology to mimic the extracellular matrix. A quantitative analysis of the influence of collagen concentration and properties on the structure and mechanics of the hydrogels is essential for tailored design adjustments for specific in vitro conditions. We combined focused ion beam scanning electron microscopy and rheology to provide a detailed quantitative atlas of the mechanical and nanoscale three-dimensional structural alterations that occur when manipulating different hydrogel's physicochemistry. Moreover, we study the effects of such alterations on the phenotype of breast cancer cells and their mechanical interactions with the extracellular matrix. Regardless of the microenvironment's pore size, porosity or mechanical properties, cancer cells are able to reach a stable mesenchymal-like morphology. Additionally, employing 3D traction force microscopy, a positive correlation between cellular tractions and ECM mechanics is observed up to a critical threshold, beyond which tractions plateau. This suggests that cancer cells in a stable mesenchymal state calibrate their mechanical interactions with the ECM to keep their migration and invasiveness capacities unaltered.
Analysis of the progressive collapse of a parking garage concrete structure due to punching shear
(Elsevier, 2025-01) Pérez Díaz, José Antonio; Ríos Jiménez, José David; Sánchez González, Estíbaliz; Ponce Torres, Alberto; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Universidad de Sevilla. TEP972: Mecánica de Materiales y Estructuras
This work aims to clarify the causes leading to the structural collapse of the garage of a residential development located in Santander, Spain, in 2020. Visual inspections of the collapsed area were carried out to establish the first hypotheses about the collapse. Subsequently, the materials, geometry and acting loads were studied to compare them with the original project. The main conclusion was that the slab was subjected, in the area where the collapse began, to gravity loads of 34 kN/m2 when it was designed to support 15 kN/m2. Then, structural verifications were performed in accordance with EHE-08 and Eurocode 2, in force during project design, to identify the failure mechanism(s) that caused the progressive collapse of the structure. Unacceptable safety factors were observed for punching shear, which was the main failure mechanism. Punching was aggravated by cavities detected in the concrete, which caused both a decrease in the slab strength (lower effective depth of the slab) and an increase in the stresses in the compression struts of about 20 % to 30 %, which considerably reduced the punching safety levels. This calculation was carried out by means of a finite element analysis with SAP2000. The assessment of this type of defect, very common during the execution phase, is not well developed either from a theoretical or regulatory point of view. This paper proposes, as a corrective measure, the inclusion both in the European and National Standards of a mandatory inspection procedure based on Ground Penetration Radar or ultrasounds, during the execution phase, to detect and correct this type of defect, not detectable by visual inspection. Finally, a bending and cracking analysis were also conducted, giving values of the corresponding safety factors of less than unity. Therefore, they also contributed to both the progressive loss of strength of the slabs and the final punching failure. These last two causes are also crucial to understand why the collapse occurred 15 years after its commissioning.
Fatigue behavior of H-section piles under lateral loads in cohesive soil
(MDPI, 2024-10-11) Pérez, José A.; Ponce Torres, Alberto; Ríos Jiménez, José David; Sánchez González, Estíbaliz; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Universidad de Sevilla. TEP972: Mecánica de Materiales y Estructuras
Most structures supporting solar panels are found on thin-walled metal piles partially driven into the ground, optimizing costs and construction time. These pile foundations are subjected to repetitive lateral loads from various external forces, such as wind, which can compromise the integrity of the pile-soil system. Given that the expected operational lifespan of photovoltaic solar plants is generally 20-30 years, predicting their service life under fatigue loads is crucial. This research analyzes the response of H-section piles to lateral fatigue loads in cohesive rigid soils through four field tests, subjected to load cycles of 55%, 72%, and 77% of the static failure load, corresponding to maximum loads of 25 kN, 32 kN, and 35 kN, respectively. Additionally, the effect of load cycles on the degradation of pile-soil adhesion is studied through two pull-out tests following cyclic tests. This study reveals that soil fatigue does not occur under repetitive loads and that soil stiffness remains constant once the cycles causing soil compaction have been overcome. Nevertheless, the accumulated plastic deflection of the soil increases steadily once soil compaction occurs due to cyclic loading. The implications of these results on the fatigue life of photovoltaic solar panel foundations are discussed.
Efecto de la adición de nanosílice en las propiedades mecánicas de un hormigón de muy alta resistencia
(Sociedad Española de Integridad Estructural. Grupo español de Fractura, 2023) Ríos Jiménez, José David; Leiva Fernández, Carlos; Cifuentes-Bulté, Héctor; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Economía y Competitividad (MINECO). España
El objetivo de este trabajo es analizar el efecto que la adición de nano-sílice, mezclado en solución líquida durante el proceso de amasado, provoca en las propiedades mecánicas de un hormigón de muy alta resistencia. Para ello, se analizaron diferentes mezclas, todas ellas con la misma composición inicial y diferentes porcentajes de nano-sílice (0,1,5; 2,5; 3,5; 5 y 7,5%). Se redujo el contenido de cemento, ya que cuando se añade nano-sílice en una cuantía mayor, la capacidad de autocompactación del hormigón disminuye. Los resultados mostraron una modificación de la estructura interna del material, los macroporos (entre 5 y 250 μm) disminuyen, mientras que los mesoporos con un radio medio que oscila entre 0,01 y 5 μm aumentan con la adición de nano-sílice. Las propiedades mecánicas del hormigón con nanosílice mejoraron hasta un 5% de sustitución. La energía de fractura de los hormigones no se vio afectada por la adición de nano-sílice. Por otro lado, la resistencia a la tracción aumentó ligeramente para el 1,5% de sustitución de nano-sílice.
Comportamiento en fractura de un hormigón de muy alta resistencia con refuerzo multiescala
(Sociedad Española de Integridad Estructural. Grupo español de Fractura, 2023) Ríos Jiménez, José David; Leiva Fernández, Carlos; Cifuentes-Bulté, Héctor; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Economía y Competitividad (MINECO). España
El uso del hormigón para fabricar torres de aerogeneradores es una de las aplicaciones estudiadas recientemente. Estas estructuras tubulares están expuestas a cargas cíclicas alternas. Este trabajo estudia el efecto de la adición de diferentes tipos de microfibras de carbono sobre el comportamiento en fractura de un hormigón de muy alta resistencia. Se han realizado ensayos experimentales sobre probetas prismáticas entalladas utilizando tres tipos de microfibras de carbono y diferentes contenidos (0-20 kg/m3). Todas las fibras tienen el mismo diámetro (7 μm) y diferentes longitudes (0,1, 3 y 6 mm). La resistencia a tracción de las microfibras de carbono es de 4.200 MPa, lo que reduce significativamente la probabilidad del mecanismo de fallo por rotura de la fibra. Los resultados mostraron que el uso de fibras de 6 mm con 20 kg/m3 permitieron alcanzar una mayor resistencia a tracción y energía de fractura, con incrementos del 100% y 105% respectivamente, en comparación con el hormigón de control. Las fibras más largas y con mayor contenido actuaron como barreras a la propagación de las grietas de manera más efectiva, pero la distribución de estas en la matriz fue menos uniforme y aumentó la dispersión de los resultados.
Evaluating edge joint preparation impact on penetration depth in laser-arc hybrid welding
(Elsevier, 2025-02) Artero Real, Ángel; Kristiansen, Morten; Frostevarg, Jan; Justo Estebaranz, Jesús; Cañas Delgado, José; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Universidad de Sevilla. TEP131: Grupo de Elasticidad y Resistencia de Materiales
Nowadays, conventional welding technologies such as submerged arc welding (SAW) are still used in most heavy-steel industries. This type of traditional technology means that welding takes up a large part of the productive time. As a solution to this problem, there are welding methods, such as Laser-Arc Hybrid Welding (LAHW), that have the potential to reduce the cost of manufacturing large steel structures. This is possible due to the reduced number of weld passes required to join thicker steel sections, as large thicknesses can be welded in one or a few passes. A problem with LAHW is achieving satisfactory quality. For this reason, it is essential to study the starting conditions, e.g. edge joint preparation. The target of this research work is to find out the relationship between the penetration value of the weld bead obtained and the edge joint preparation. The evolution of the molten pool and the behavior of the molten material in the joint is discussed for the different edge joint preparation configurations. The effect of the roughness is that it affects the wetting of the molten material in the joint, which would affect the penetration result, together with the gap and air volume gap used in the joint. Cut-wire is also used in the research, in samples that presented a larger air volume gap. The behavior of the molten metal inside the joint in this case is also discussed. In addition, the quality of the weld beads has also been determined by making macrographs, microstructural analysis, X-ray, microhardness profiles, tensile test and Charpy test. Some pores and cracks have been found, although destructive tests show adequate behavior of the weld bead. It is possible to elucidate from the findings that as the roughness, gap and/or air volume gap of the edge joint increases, the penetration value obtained increases. Cut-wire samples obtained full penetration.
Probabilistic fatigue analysis of ultra-high-performance fibre-reinforced concrete under thermal effects
(EDP Sciences, 2018-05-25) Ríos Jiménez, José David; Cifuentes-Bulté, Héctor; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Economía y Competitividad (España)
This paper describes the influence of the temperature and the fibre reinforcementon the flexuralfatigue behaviourof an ultra-high-performance fibre-reinforced concrete. Three-point bending fatigue tests were carried out for an ultra-high-performance concrete subjected to different temperatures ranging from room temperature up to 300 ºC and considering three different types of reinforcement: a) steel fibres, b) hybrid steel and polypropylene fibres and c) non-reinforced (reference matrix). The fatigue behaviour was assessed from the S-N fields obtained through a probabilistic fatigue model developed by Castillo and Fernández-Canteli. The influence ofthe type of reinforcement on the fatigue behaviour was analysedby S-N curves.An analysis of the thermal effectsin the fatigue life of the ultra-high-performance concretehas also been carried out. The results showed the most suitable fibre reinforcement among the analysed options to get the best fatigue behaviourin accordance to the exposure temperature.
Behavior of High-Strength Polypropylene Fiber-Reinforced Self-Compacting Concrete Exposed to High Temperatures
(ASCE - The American Society of Civil Engineers, 2018-11-01) Ríos Jiménez, José David; Cifuentes-Bulté, Héctor; Leiva Fernández, Carlos; García Arenas, Celia; Alba, María D.; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Economía y Competitividad (España); Universidad de Sevilla. TEP972: Mecánica de materiales y estructuras
The utilization of structural high-performance concrete reinforced with polypropylene fibers in applications demanding long exposure times to high temperatures, such as in case of thermal energy storage systems, is analyzed in this work. Different temperatures: 100, 300, 500 and 700°C (hot), as well as cooled-down states (cold) and different exposure times (6, 24 and 48 h) have been analyzed. The thermogravimetric analysis, fracture behavior, compressive strength, the Young’s modulus and tensile strength of concrete were also experimentally determined and subsequently, a comprehensive analysis of the thermal and mechanical behavior of highperformance concrete under different thermal conditions has been carried out, broadening with longer exposure times the available results about the behavior of high-performance fiber reinforced concrete subjected to high-temperatures. When the temperature is increased, the mechanical properties of this concrete diminishes. The results shown that once thermal and moisture equilibriums are reached there is no influence of the exposure time. They provide useful information about the influence of different parameters of fiber-reinforced concrete subjected to high temperatures.
Analysis of the main geometrical characteristics that affect the bonding of ribs in rebars thinly covered to repair masonry structures
(Elsevier, 2021-11-01) Rodríguez-Mayorga, Esperanza; Hortigón Fuentes, Beatriz; Fernández Ancio, Fernando; Universidad de Sevilla. Departamento de Estructuras de Edificación e Ingeniería del Terreno; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Agencia Estatal de Investigación. España; Universidad de Sevilla. TEP245: Ingeniería de las Estructuras; Universidad de Sevilla. TEP206: Sath Sostenibilidad en Arquitectura, Tecnología y Patrimonio: Materialidad y Sistemas Constructivos; Universidad de Sevilla. TEP963: Ingeniería de Estructuras y Materiales
The use of stainless steel rebars in the repair of masonry structures is widespread and has traditionally produced excellent results. In these cases, rebars usually present diameters of below 8 mm covered with thin layers of mortar or grout. Research is necessary to characterise bonding under these particular conditions, hitherto unavailable. In this research, the geometry of ribs is parameterised and later analysed through the Finite Element Method. To this end, the Microplane model and Cohesive zone model are employed. Based on the numerical results, the geometrical aspects of the ribs that mostly affect bonding are identified and discussed.
Identification of microplane coefficients to reproduce the behaviour of ultrafine blast-furnace slag binder grout samples
(Springer, 2024-08-17) Rodríguez-Mayorga, Esperanza; Jiménez Alonso, Javier Fernando; Santiago Espinal, José Antonio; Fernández Ancio, Fernando; Hortigón Fuentes, Beatriz; Universidad de Sevilla; Agencia Estatal de Investigación. España; Junta de Andalucía; US.20-08; Universidad de Sevilla. TEP245: Ingeniería de las Estructuras; Universidad de Sevilla. TEP963: Ingeniería de Estructuras y Materiales; Universidad de Sevilla. TEP206: Sath Sostenibilidad en Arquitectura, Tecnología y Patrimonio: Materialidad y Sistemas Constructivos
Ultra-fine blast-furnace slag binders have recently been introduced to repair masonry. The reduced particle diameter of these binders makes them especially suitable for use as grouts, since this characteristic enables these grouts to fill even the smallest voids. The current necessity and effectiveness of Finite Element Analysis in any process concerning construction, repair or reinforcement of building structures remains unquestionable. In this way, the calibration of Finite Element material models for their correct performance has become compulsory. Regarding quasi-brittle materials, such as mortar and grouts, the Microplane model is recommended to reproduce their behaviour. This paper is targeted towards obtaining Microplane model coefficients to exactly reproduce the behaviour of ultrafine blast-furnace slag grout samples. To this end, several compressive tests have been carried on in order to obtain the experimental stress–strain curves that define the behaviour of these samples. Furthermore, reverse engineering by means of an optimisation algorithm successfully attained the possible coefficients to reproduce this material with the Microplane model. The correctness of these coefficients has been verified with a new campaign composed of compressive tests, Double Punch tests, and flexural tests. These tests have been reproduced by Finite Element Analysis, thereby confirming the accuracy of the set of coefficients. Thus, two are the main conclusions obtained: (1) the framework for the modelling of ultra-fine blast-furnace slag grout elements based-on the Microplane model has been proposed, implemented and validated; and (2) a value for the coefficients of the abovementioned model has been proposed.
Flexoelectric anisotropy and shear contributions in lead-free piezocomposites
(Elsevier, 2024-09) Jagdish, A.K.; Buroni Cuneo, Federico Carlos; Melnik, Roderick; Rodríguez de Tembleque Solano, Luis; Sáez Pérez, Andrés; Universidad de Sevilla. Departamento de Ingeniería Mecánica y de Fabricación; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER)
Flexoelectricity is the coupling between strain gradients and electric fields. This phenomenon can significantly enhance piezocomposite response in addition to linear piezoelectricity. This enhancement is especially important for lead-free piezocomposites, which generally underperform compared to lead-based counterparts. Flexoelectric enhancement is facilitated by structural anisotropy in piezocomposites. However, challenges in modeling flexoelectric effects arise from several unknowns. Firstly, the shear flexoelectric coefficient is not wellcharacterized experimentally. Secondly, significant discrepancies exist between theoretical predictions and experimental measurements of flexoelectric coefficients. Thirdly, the influence of matrix mechanical properties on flexoelectric behavior is poorly understood. To address these issues, we construct a parametric flexoelectric model of a lead-free piezocomposite with graded inclusion concentration. We then systematically analyze the impact of each parameter to identify which significantly influence flexoelectric behavior. This study is intended to provide direction to further experimental studies towards understanding and tailoring this subset of parameters
Influence of graphene oxide concentration and ultrasonication energy on fracture behavior of nano-reinforced cement pastes
(MDPI, 2024-08-05) Ríos Jiménez, José David; Leiva Fernández, Carlos; Martínez de la Concha, Antonio; Ariza Moreno, María del Pilar; Cifuentes-Bulté, Héctor; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Junta de Andalucía; Ministerio de Ciencia e Innovación (MICIN). España; Universidad de Sevilla. TEP972: Mecánica de Materiales y Estructuras; Universidad de Sevilla. TEP142: Ingeniería de Residuos
The aim of this study is twofold. First, to assess the effect of the sonication process on the optimal dispersion of GO sheets for nanostructural reinforcement of cement pastes, as there is currently no clear criterion on this effect in the literature. For this purpose, in the first stage, the GO content in distilled water was fixed at 0.03% by weight, and the sheets were dispersed using different levels of ultrasonic energy, ranging from 0 J/mL to 2582 J/mL. In the second stage, to analyze the modification of pore structure due to the addition of GO sheets in different ratios (0–0.06% by weight) and its relationship with the mechanical and fracture properties of reinforced cement pastes. According to the results, it has been determined that the incorporation of GO sheets into the matrix alters the mechanical and fracture behavior, varying depending on matrix pore size and GO particle size. The addition of GO leads to a reduction in the average size of macropores (greater than 8 µm) of 13% for a dosage of 0.45% in weight and micropores (between 8 and 0.5 µm) in a 64% for the same composition with non-sonicated GO, although the total volume of pores in these ranges only decreased slightly. This reduction is more pronounced when the GO has not been sonicated and has larger particle size. Sonicated GO primarily modifies the range of capillary pores (<0.5 µm). The addition of GO with the highest degree of dispersion (465 nm) did not show significant improvements in compressive strength or Young’s modulus, as the cement used contains a significant volume of macropores that are not substantially reduced in any composition. Adding 0.030% ultrasonicated GO achieved a 7.8% increase in fracture energy, while an addition of 0.045% resulted in a 13.3% decrease in characteristic length, primarily due to the effect of capillary and micropores.
Effect of the level of anisotropy on the macroscopic failure of notched thin-ply laminates
(Elsevier, 2024-11) Mitrou, Anatoli; Arteiro, Albertino; Reinoso Cuevas, José Antonio; Camanho, Pedro P.; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; European Union (UE). H2020; Ministerio de Ciencia e Innovación (MICIN). España; Universidad de Sevilla. TEP963: Ingeniería de Estructuras y Materiales
This work presents a detailed experimental study conducted for a range of different lay-ups using thin-ply carbon fiber reinforced polymer (CFRP) laminates. The selection of the laminates was performed relying on their level of anisotropy. The laminates vary from a quasi-isotropic (QI) laminate, which is weakly anisotropic, to a cross-ply (CP) laminate, which is strongly anisotropic. The laminates were tested in on-axis and off-axis open hole tension (OHT). The main objective was to observe the effect of the level of anisotropy of the laminate on the macroscopic failure and observed failure patterns. It is shown that, contrary to most existing observations so far, depending on the lay-up and consequently its level of anisotropy, open-hole, quasi-homogeneous thin-ply laminates do not necessarily exhibit a fiber dominated failure mode, but could develop sub-critical damage mechanisms in a large extent prior to ultimate failure, reminiscent of what is observed for standard-ply CFRP laminates.

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