http://hdl.handle.net/10366/4369 2026-09-15T23:44:16Z 2026-09-15T23:44:16Z Toribio Quevedo, Jesús Andrés Ayaso Yáñez, Francisco Javier Lorenzo Fernández, Miguel Ángel http://hdl.handle.net/10366/172795 2026-09-15T00:02:22Z 2026-01-01T00:00:00Z

[EN]Hydrogen embrittlement (HE) is a primary cause of in-service failure of pearlitic prestressing steels, compromising the long-term durability and safety of prestressed concrete structures. This fracture process causes a material brittle fracture due to hydrogen-assisted micro-damage (HAMD). The main stage of HE is hydrogen transport by diffusion towards critical locations, a process highly sensitive to hydrostatic stress and plastic strain gradients. Accordingly, different HAMD scenarios to analyse HE in prestressing steels are defined in this study by modifying the stress and strain fields through sharp notches and mechanical preloading to induce residual stress and strains. To achieve this goal, two sharply-notched geometries were considered varying notch depth, shallow notch and deep notch. Both preloaded (90% of in-air fracture load) and un-preloaded notched samples were tested under a constant loading (70% of in-air fracture load) up to final fracture in the presence of an environment (saturated solution of Ca(OH)2 with 0.1 g/l NaCl) under electrochemical conditions (pH =12.5, E = −1200 mV SCE, saturated calomel electrode) promoting HE. Fractographic analysis via SEM of the fracture surfaces was performed to analyse the variations on the HAMD scenarios. The obtained results reveal different HE behaviours: shallow notches exhibited highly localized hydrogen damage and shorter time-to-failure, whereas deep notches resulted in more distributed damage and extended fracture lives.

2026-01-01T00:00:00Z Rodríguez Martín, Manuel Prieto Sánchez, Carlos Javier García Martín, Roberto José Lorenzo Fernández, Miguel Ángel http://hdl.handle.net/10366/172788 2026-09-15T00:02:20Z 2025-01-01T00:00:00Z

[ES]En este trabajo, se lleva a cabo una investigación prospectiva utilizando fuentes abiertas para identificar y analizar las organizaciones que se benefician de la fabricación aditiva en la región transfronteriza entre el oeste de España y el norte de Portugal. El objetivo es evaluar la especialización empresarial en el contexto de esta tecnología propia de la Industria 4.0 en dos regiones caracterizadas por procesos de despoblación y desindustrialización. La metodología adoptada incluye una búsqueda sistemática basada en criterios predefinidos, seguida de un análisis cuantitativo en base a tres factores de estratificación: tamaño organizacional, objetivos empresariales, localización geográfica, cifras de venta y número de empleados. Además, se realiza un análisis cualitativo y heurístico de la información accesible sobre las organizaciones clave, explorando su vinculación con el desarrollo socioeconómico regional. [EN]In this paper, a prospective investigation is conducted using open sources on organizations benefiting from additive manufacturing in the cross-border region between western Spain and northern Portugal. This work aims to assess business specialization within the framework of this Industry 4.0 technology in two areas affected by depopulation and deindustrialization processes. The adopted methodology includes a systematic search based on predefined criteria, followed by a quantitative analysis based on three stratification factors: company size, business objectives, and geographic location. Additionally, a qualitative and heuristic analysis of open information from key organizations and their relationship with regional socio-economic development is carried out.

2025-01-01T00:00:00Z Psarras, Spyridon Muñoz Sánchez, Raúl Ghajari, Mazdak http://hdl.handle.net/10366/172749 2026-09-12T00:01:43Z 2023-01-01T00:00:00Z

[EN]This paper reports on a study of the damage tolerance of carbon fibre reinforced polymer plates, used in aircraft fuselage, subjected to multi-site impacts. A new fixture was designed to perform sequential low-velocity impacts at different locations on plates with two different thicknesses, representing upper and lower fuselage panels. The residual strength in compression was measured using a new compression-after-impact rig designed to prevent global buckling of thin plates. Experimental results indicated that compared to single impacts, multi-site impacts can reduce the residual strength of the thin plates, but not the thick plates. To explain this difference, a detailed finite element model was developed, which enabled modelling of multi-site impacts and compression after impact in one simulation. Simulations suggested that the second impact damage changes the buckled shape prior to failure for the thin plates. A parametric analysis on key material parameters showed that they have a small effect on the residual compressive strength. This work can help to improve the design of aircraft panels with respect to threats posed by multi-site impacts.

2023-01-01T00:00:00Z Muñoz Sánchez, Raúl Seltzer, Rocío Martínez, Vanesa González, Carlos Llorca, Javier http://hdl.handle.net/10366/172747 2026-09-12T00:01:41Z 2024-01-15T00:00:00Z

[EN]This paper evaluates the impact performance of various materials against single and repeated low-velocity impacts. The objective is to identify a lightweight, thin, and cost-effective bumper that can effectively protect a composite aircraft structure. Drop-weight impact tests were performed on eight candidate materials with similar areal densities, including three 3D woven and three 2D woven composites, an aluminium alloy (Al 7075 T6) and an aluminium foamed sandwich. To enable a comparison of impact performance across materials with different characteristics, a normalisation method was defined for both single and repeated impact loading. The relationship between single and repeated low-velocity impacts was also explored. Finally, the influence of adding a polymeric foam on the amount of energy transmitted to the composite airframe was also discussed. The results indicate that, overall, the 3D woven composites exhibited superior impact performance in all tested scenarios.

2024-01-15T00:00:00Z Izard Anaya, Eulalia García Martín, Roberto José Rodríguez Martín, Manuel Lorenzo Fernández, Miguel Ángel http://hdl.handle.net/10366/169373 2026-01-30T01:01:21Z 2025-01-01T00:00:00Z

[EN] The interference fit is a common process for the assembly of mechanical parts on a shaft for diverse mechanical engineering applications. One of the manufacturing methods consists of introducing a shaft into a hub by applying a force being the hub diameter lower than the shaft diameter. This way, contact pressure is generated at the shaft–hub interface at the end of the process, enabling torque transmission. Thus, a non-uniformly distributed stress state appears at the shaft–hub interface with significant stress peaks at the hub edges. In addition, as a consequence of the manufacturing process, local plasticity is generated in the hub on the insertion side causing changes in stress distributions. In this paper, an analysis based on finite elements simulations is carried out to reveal the influence of, on one hand, manufacturing parameters such as friction on stress concentrations at the interface and, on the other hand, geometrical parameters such as hub chamfer angle, considering chamfer hubs and conventional hubs. To achieve this goal, different simulations of the mechanical manufacturing process of the axial assembly of press fits are carried out to reveal the stress fields at the interface. Thus, stress concentrations under different friction conditions from a case without friction to a dry friction case are revealed and analyzed. The results show, on one hand, the friction coefficient as a highly influential factor, causing asymmetrical stress distributions with high stress concentrations that reduce the mechanical performance of press fits and, on the other hand, the beneficial impact of chamfer hubs for lowering stress concentrations.; [ES] El ajuste por interferencia es un proceso común para el ensamblaje de piezas mecánicas en ejes para diversas aplicaciones de ingeniería mecánica. Uno de los métodos de fabricación consiste en introducir un eje en un cubo aplicando una fuerza cuyo diámetro es menor que el del eje. De esta manera, se genera presión de contacto en la interfaz eje-cubo al final del proceso, lo que permite la transmisión de par. Por lo tanto, se genera un estado de tensión distribuido de forma no uniforme en la interfaz eje-cubo, con picos de tensión significativos en los bordes del cubo. Además, como consecuencia del proceso de fabricación, se genera plasticidad local en el cubo en el lado de inserción, lo que provoca cambios en la distribución de tensiones. En este artículo, se realiza un análisis basado en simulaciones de elementos finitos para revelar la influencia de, por un lado, parámetros de fabricación como la fricción en las concentraciones de tensiones en la interfaz y, por otro, parámetros geométricos como el ángulo de chaflán del cubo, considerando cubos con chaflán y cubos convencionales. Para lograr este objetivo, se realizan diferentes simulaciones del proceso de fabricación mecánica del ensamblaje axial de ajustes a presión para revelar los campos de tensión en la interfaz. De este modo, se revelan y analizan las concentraciones de tensión en diferentes condiciones de fricción, desde un caso sin fricción hasta un caso de fricción en seco. Los resultados muestran, por un lado, que el coeficiente de fricción es un factor muy influyente, causando distribuciones asimétricas de tensión con altas concentraciones que reducen el rendimiento mecánico de los ajustes a presión y, por otro, el efecto beneficioso de los cubos chaflanados para reducir las concentraciones de tensión.

2025-01-01T00:00:00Z Izard Anaya, Eulalia García Martín, Roberto José Rodríguez Martín, Manuel Lorenzo Fernández, Miguel Ángel http://hdl.handle.net/10366/169372 2026-01-30T01:01:15Z 2023-01-01T00:00:00Z

[EN] The theoretical expressions commonly used in the design of interference fits do not take into account the huge stress concentrations located at the edges of the hub. This underestimation of the real stress state can induce the incorrect performance of the shaft–hub assembly. Among the different methods to address this problem is the use of chamfer hubs, which are used for reducing such stress concentrations. In this paper, an analysis, performed via finite element method, of the influence of the geometric parameters of a shrink fit with chamfer hubs was carried out with the aim of determining the optimal dimensions for the design of this type of mechanical assembly. To achieve this goal, different chamfer hub geometries were considered: (i) full–chamfer hubs defined by the chamfer angle and (ii) partial–chamfer hubs defined by the chamfer angle and the chamfer height. According to the obtained results, stress concentrations can be reduced by using a full–chamfer hub with chamfer angles within the range 13°–15° depending on the hub thickness. In addition, similar results can be obtained by using partial–chamfer hubs with a chamfer height of half of the hub thickness and chamfer angles within the range 13°–15°. By using these design recommendations, the theoretical equations can be used without underestimating the real stress state.; [ES] Las expresiones teóricas comúnmente utilizadas en el diseño de ajustes por interferencia no consideran las altas concentraciones de tensión localizadas en los bordes del cubo. Esta subestimación del estado real de tensión puede inducir el funcionamiento incorrecto del conjunto eje-cubo. Entre los diferentes métodos para abordar este problema se encuentra el uso de cubos chaflanados, que se utilizan para reducir dichas concentraciones de tensión. En este trabajo, se realizó un análisis, realizado mediante el método de elementos finitos, de la influencia de los parámetros geométricos de un ajuste por contracción con cubos chaflanados con el objetivo de determinar las dimensiones óptimas para el diseño de este tipo de conjunto mecánico. Para lograr este objetivo, se consideraron diferentes geometrías de cubos chaflanados: (i) cubos con chaflán completo definidos por el ángulo del chaflán y (ii) cubos con chaflán parcial definidos por el ángulo y la altura del chaflán. De acuerdo con los resultados obtenidos, las concentraciones de tensión se pueden reducir utilizando un cubo con chaflán completo con ángulos de chaflán dentro del rango de 13° a 15°, dependiendo del espesor del cubo. Además, se pueden obtener resultados similares utilizando cubos con chaflán parcial, con una altura de chaflán de la mitad del espesor del cubo y ángulos de chaflán entre 13° y 15°. Con estas recomendaciones de diseño, se pueden aplicar las ecuaciones teóricas sin subestimar el estado de tensión real.

2023-01-01T00:00:00Z Rodríguez-Martín, Manuel Lorenzo, Miguel Izard Anaya, Eulalia García Martín, Roberto José Rodríguez Martín, Manuel http://hdl.handle.net/10366/169370 2026-01-30T01:01:20Z 2023-01-01T00:00:00Z

[EN] Press fits are a simple and effective method for assembling a shaft into a hub for different applications in the mechanical engineering field. This method consists of forcing to pass a shaft into a hub via axial insertion. As a result of the difference in the diameters of both components of the shaft and hub, a radial interference is generated, causing a contact pressure at the interface shaft–hub. Contact pressure and the friction coefficient are key factors influencing the maximum transmitted torque. So, in this study, different scenarios for the assembly of a press fit were simulated using finite elements (FE) in order to reveal the influence of this key parameter on the manufacturing-induced stresses in the hub. This way, different friction conditions were considered in terms of the friction coefficient from the frictionless case to a case of high dry friction. In addition, different hub geometries were analyzed including conventional hubs and chamfer hubs with optimal geometry that allows lowering the localized stress concentrations at the hub edges. This way, a more realistic estimation of the final stress state of a press fit is obtained. According to the obtained results, the friction coefficient is revealed as a key parameter in the resulting stress field, causing a non-uniform distribution of stress that can affect the mechanical performance of the press-fit assembly.; [ES] Los ajustes a presión son un método simple y efectivo para ensamblar un eje en un cubo para diversas aplicaciones en ingeniería mecánica. Este método consiste en forzar el paso de un eje en un cubo mediante inserción axial. Como resultado de la diferencia en los diámetros de ambos componentes, el eje y el cubo, se genera una interferencia radial que genera una presión de contacto en la interfaz eje-cubo. La presión de contacto y el coeficiente de fricción son factores clave que influyen en el par máximo transmitido. Por lo tanto, en este estudio, se simularon diferentes escenarios para el ensamblaje de un ajuste a presión mediante elementos finitos (EF) para revelar la influencia de este parámetro clave en las tensiones inducidas por la fabricación en el cubo. De esta manera, se consideraron diferentes condiciones de fricción en términos del coeficiente de fricción, desde un caso sin fricción hasta un caso de alta fricción en seco. Además, se analizaron diferentes geometrías de cubo, incluyendo cubos convencionales y cubos chaflanados con una geometría óptima que permite reducir las concentraciones de tensión localizadas en los bordes del cubo. De esta manera, se obtiene una estimación más realista del estado de tensión final de un ajuste a presión. De acuerdo con los resultados obtenidos, el coeficiente de fricción se revela como un parámetro clave en el campo de tensiones resultante, provocando una distribución no uniforme de la tensión que puede afectar al rendimiento mecánico del conjunto prensado.

2023-01-01T00:00:00Z Izard Anaya, Eulalia García Martín, Roberto José Rodríguez Martín, Manuel Lorenzo Fernández, Miguel Ángel http://hdl.handle.net/10366/169369 2026-01-30T01:01:17Z 2022-01-01T00:00:00Z

[EN] As it is well known, shrink fits exhibit a stress concentration at the hub edges that can cause the failure of such mechanical components. A method for reducing such a stress concentration is placing a contact ring between the hub and the shaft. To achieve the desired effect, the Young Modulus of the material used for the contact ring must be lower than the one used in the hub and the shaft. Unfortunately, there are no design methods for estimating the optimal dimensions or materials of the contact ring. To fill this gap, in this study, diverse numerical simulations by the finite elements method (FEM) were carried out considering different geometries and materials in order to obtain recommendations that allow mechanical designers to significantly reduce the stress concentrations in these components. According to the obtained results, a contact ring of 25% of the hub thickness allows to significantly reduce up to 40% of the stress concentration. In addition, a linear influence of the stress reduction with the Young modulus was found thereby, and the most recommendable material for the contact ring is the one with the lowest Young modulus. On the other hand, according to the obtained results, the influence of the Poisson coefficient can be considered negligible.; [ES] Como es bien sabido, los ajustes por contracción presentan una concentración de tensiones en los bordes del cubo que puede provocar la falla de dichos componentes mecánicos. Un método para reducir dicha concentración consiste en colocar un anillo de contacto entre el cubo y el eje. Para lograr el efecto deseado, el módulo de Young del material utilizado para el anillo de contacto debe ser menor que el utilizado en el cubo y el eje. Desafortunadamente, no existen métodos de diseño para estimar las dimensiones o materiales óptimos del anillo de contacto. Para subsanar esta deficiencia, en este estudio se realizaron diversas simulaciones numéricas mediante el método de elementos finitos (MEF), considerando diferentes geometrías y materiales, con el fin de obtener recomendaciones que permitan a los diseñadores mecánicos reducir significativamente la concentración de tensiones en estos componentes. Según los resultados obtenidos, un anillo de contacto del 25 % del espesor del cubo permite reducir significativamente hasta un 40 % la concentración de tensiones. Además, se observó una influencia lineal de la reducción de tensiones con el módulo de Young, y el material más recomendable para el anillo de contacto es el que presenta el módulo de Young más bajo. Por otra parte, según los resultados obtenidos, la influencia del coeficiente de Poisson puede considerarse insignificante.

2022-01-01T00:00:00Z Toribio Quevedo, Jesús Andrés Lorenzo Fernández, Miguel Ángel http://hdl.handle.net/10366/169247 2026-01-27T09:50:26Z 2022-12-19T00:00:00Z

[EN] The main cause of in-service failure of cold drawn wires in aggressive environments is hydrogen embrittlement (HE). The non-uniform plastic strains and residual stresses generated after cold drawing play a significant role in the matter of HE susceptibility of prestressing steels. In this paper, a new and innovative design of the drawing scheme is developed, geared towards the reduction in both manufacturing-induced residual stresses and plastic strains. To achieve this goal, three innovative cold drawing chains (consisting in diverse multi-step dies where multiple diameter reductions are progressively carried out in a single die) are numerically simulated by the finite element (FE) method. From the residual stress and plastic strain fields revealed from FE numerical simulations, hydrogen accumulation for diverse times of exposure is obtained by means of FE simulations of the hydrogen diffusion assisted by stress and strains. Thus, an estimation of the HE susceptibility of the cold drawn wires after each process was obtained. Results reveal that cold drawn wire using multi-step dies exhibits lower stress and strain states nearby the wire surface. This reduction causes a decrease in the hydrogen concentration at the prospective damage zones, thereby improving the performance of the prestressing steel wires in hydrogenating environments promoting HE. Thus, the optimal wire drawing process design is carried out using special dies with several reductions per die.; [ES] La principal causa de fallos en servicio de los alambres trefilados en frío en entornos agresivos es la fragilización por hidrógeno (FE). Las deformaciones plásticas no uniformes y las tensiones residuales generadas tras el trefilado en frío influyen significativamente en la susceptibilidad a la FE de los aceros de pretensado. En este artículo, se desarrolla un diseño innovador del esquema de trefilado, orientado a la reducción tanto de las tensiones residuales como de las deformaciones plásticas inducidas por la fabricación. Para lograr este objetivo, se simulan numéricamente tres innovadoras cadenas de trefilado en frío (que constan de diversas matrices multietapa donde se realizan múltiples reducciones de diámetro progresivamente en una sola matriz) mediante el método de elementos finitos (EF). A partir de los campos de tensiones residuales y deformaciones plásticas revelados por las simulaciones numéricas de EF, se obtiene la acumulación de hidrógeno para diversos tiempos de exposición mediante simulaciones de EF de la difusión de hidrógeno asistida por tensiones y deformaciones. De este modo, se obtiene una estimación de la susceptibilidad a la FE de los alambres trefilados en frío después de cada proceso. Los resultados revelan que el alambre trefilado en frío utilizando matrices multietapa presenta menores estados de tensión y deformación cerca de la superficie del alambre. Esta reducción provoca una disminución de la concentración de hidrógeno en las zonas de posible daño, mejorando así el rendimiento de los alambres de acero de pretensado en entornos hidrogenantes que promueven la hidrogenación. Por lo tanto, el diseño óptimo del proceso de trefilado se realiza utilizando matrices especiales con varias reducciones por matriz.

2022-12-19T00:00:00Z Rodríguez-García, Verónica Izquierdo Martín, Carlos Martínez, Vanesa Guzmán de Villoria, Roberto http://hdl.handle.net/10366/167956 2026-07-15T00:01:35Z 2025-01-01T00:00:00Z

[EN] Brick-and-mortar carbon fibre laminates combine high damage tolerance, multiple energy-dissipation mechanisms, and improved formability. However, compared with their properties found in natural materials, their mechanical performance is still really limited. One of the main advantages of natural materials is their complex structure, composed of several hierarchical levels at different scales. Regarding carbon fibre laminates, numerous works have shown the advantages of adding a small amount of nanofiller, but their behaviour in brick-and-mortar structures has still not fully understood. In this work, we have investigated the effect of graphene oxide in carbon fibre/epoxy brick-and-mortar laminates. We fabricated continuous and 25-mm length brick-and-mortar laminates from standard prepreg and prepreg filled with graphene oxide (0.68 wt%.). Tensile tests, Mode I (double cantilever test), and Mode II (thee point end-notched flexure) fracture test were carried out. Despite the low amount of graphene oxide, a slight increase in properties have been observed.; [ES] Los laminados de fibra de carbono tipo ladrillo y mortero combinan una alta tolerancia al daño, múltiples mecanismos de disipación de energía y una mejor conformabilidad. Sin embargo, en comparación con las propiedades de los materiales naturales, su rendimiento mecánico aún es bastante limitado. Una de las principales ventajas de los materiales naturales es su compleja estructura, compuesta por varios niveles jerárquicos a diferentes escalas. En el caso de los laminados de fibra de carbono, numerosos estudios han demostrado las ventajas de añadir una pequeña cantidad de nanofibras, pero su comportamiento en estructuras tipo ladrillo y mortero aún no se comprende del todo. En este trabajo, hemos investigado el efecto del óxido de grafeno en laminados tipo ladrillo y mortero de fibra de carbono/epoxi. Fabricamos laminados tipo ladrillo y mortero continuos y de 25 mm de longitud a partir de preimpregnado estándar y preimpregnado con óxido de grafeno (0,68 % en peso). Se realizaron ensayos de tracción, de fractura en modo I (doble voladizo) y de fractura en modo II (flexión con muesca en el extremo de tres puntos). A pesar de la baja cantidad de óxido de grafeno, se ha observado un ligero aumento en las propiedades.

2025-01-01T00:00:00Z Izquierdo Martín, Carlos Muñoz Sánchez, Raúl Martínez, Vanesa Maestro, César Cañibano, Esteban Guzmán de Villoria, Roberto http://hdl.handle.net/10366/167925 2025-12-19T12:30:36Z 2025-01-01T00:00:00Z

[EN] Brick-and-mortar carbon fibre structures have attracted considerable attention owing to their reliable mechanical performance and processability. Their primary advantages include high damage tolerance, multiple energy dissipation mechanisms and the potential to use carbon fibre scraps instead of pristine carbon fibre prepregs. However, their behaviour under specific loading conditions, particularly Mode I and Mode II fracture, remains unclear. Moreover, while most studies have focused on thermoset matrix systems, research on brick-and-mortar composites with high-performance thermoplastic matrices remains scarce. To address this, the present study investigated the mechanical behaviour of brick-and-mortar laminates fabricated from carbon fibre/poly-ether-ether-ketone tapes. Tensile, Mode I (double cantilever beam) and Mode II (three-point end-notched flexure) fracture tests were conducted. Numerical simulations were also conducted to examine the underlying failure mechanisms, yielding good agreement with experimental observations.; [ES] Las estructuras de fibra de carbono tipo ladrillo y mortero han atraído considerable atención debido a su fiable rendimiento mecánico y procesabilidad. Sus principales ventajas incluyen una alta tolerancia al daño, múltiples mecanismos de disipación de energía y la posibilidad de utilizar restos de fibra de carbono en lugar de preimpregnados de fibra de carbono vírgenes. Sin embargo, su comportamiento bajo condiciones de carga específicas, en particular la fractura en Modo I y Modo II, aún no está claro. Además, si bien la mayoría de los estudios se han centrado en sistemas de matriz termoestable, la investigación sobre compuestos tipo ladrillo y mortero con matrices termoplásticas de alto rendimiento sigue siendo escasa. Para abordar esta cuestión, el presente estudio investigó el comportamiento mecánico de laminados tipo ladrillo y mortero fabricados con cintas de fibra de carbono/poliéter-éter-cetona. Se realizaron ensayos de tracción, fractura en Modo I (viga doble en voladizo) y fractura en Modo II (flexión en tres puntos con muesca en el extremo). También se llevaron a cabo simulaciones numéricas para examinar los mecanismos de fallo subyacentes, obteniendo una buena concordancia con las observaciones experimentales.

2025-01-01T00:00:00Z González Herráez, Miguel Martínez, Vanesa Rodríguez-García, Verónica Herráez, M. Rodríguez García, Verónica Guzmán de Villoria, Roberto http://hdl.handle.net/10366/160059 2025-04-30T20:18:23Z 2022-01-01T00:00:00Z

[EN] Natural structures such as nacre show an outstanding balance of strength and toughness, despite comprising mainly brittle constituents; this is a highly desirable combination of properties scarcely seen in synthetic composites. In this study, carbon fibre-reinforced polymer (CFRP) laminates mimicking the structure of nacre (‘brick-and-mortar’) were manufactured using the automated tape laying (ATL) technique, as a means of enhancing their interlaminar properties and fracture toughness. The interlaminar fracture toughness of the bio-inspired CFRP laminates was measured via double cantilever beam (DCB) and three-point bending end-notched flexure (3ENF) tests. The results indicated increments of up to 32% and 92%, respectively, in the interlaminar fracture toughness when compared with that of conventional continuous CFRP samples. In addition, the translaminar fracture toughness of the developed nacre-inspired CFRPs was measured through a compact tension (CT) test, which revealed increments of up to 30%. Finally, different reinforcement mechanisms were analysed to understand the effect of the ‘brick-and-mortar’ structure.

2022-01-01T00:00:00Z Rodríguez García, Verónica Guzmán de Villoria, Roberto http://hdl.handle.net/10366/159542 2025-04-30T20:18:23Z 2021-01-01T00:00:00Z

[EN] Carbon-fibre reinforced polymers (CFRPs) present outstanding mechanical performance per unit of mass; however, they also fail in a brittle manner, with little or no warning of their forthcoming catastrophic failure. In this study, a ‘brick-and-mortar’ design inspired by the structure of nacre was implemented by automated tape lay-up for the first time with the aim of changing the failure response of CFRPs. Standard procedures and materials already implemented in the aerospace industry have been used to produce bio-inspired CFRPs laminates, providing the first example of bio-inspired concepts scaled-up to industrial level. The effects of the proposed automated manufacturing process on the morphology and tensile properties of the laminates were investigated. A non-linear response was observed when the bio-inspired laminates were subjected to tensile forces. This type of response agrees with those of previous studies on lab-scale manufactured aligned discontinuous CFRPs.

2021-01-01T00:00:00Z Rodríguez Martín, Manuel Fueyo, José G. López Rebollo, Jorge González Aguilera, Diego García-Martín, Roberto Madruga, F. http://hdl.handle.net/10366/159541 2025-04-30T20:18:24Z 2022-01-01T00:00:00Z

[EN] A methodology based on step-heating thermography for predicting the length dimension of small defects in additive manufacturing from temperature data measured on thermal images is proposed. Regression learners were applied with different configurations to predict the length of the defects. These algorithms were trained using large datasets generated with Finite Element Method simulations. The different predictive methods obtained were optimized using Bayesian inference. Using predictive methods generated and based on intrinsic performance results, knowing the material characteristics, the defect length can be predicted from single temperature data in defect and non-defect zone. Thus, the developed algorithms were implemented in a laboratory set-up carried out on ad-hoc manufactured parts of Nylon and polylactic acid which include induced defects with different sizes and thicknesses. Using the trained algorithm, the deviation of the predicted results for the defect size varied between 13% and 37% for PLA and between 13% and 36% for Nylon.

2022-01-01T00:00:00Z Muñoz Sánchez, Raúl Seltzer, Rocío Sket, Federico González, Carlos Llorca, Javier http://hdl.handle.net/10366/159440 2025-04-30T20:18:24Z 2022-01-01T00:00:00Z

[EN] This study investigates the low velocity impact behaviour and the energy absorption capability of a hybrid 3D woven composite made from S2-glass (GF), T700 carbon (CF) and Dyneema fibres. The laminate was asymmetric, having a high concentration of CF on one side and GF on the other. Experimental results revealed a pseudo-ductile behaviour of the material and a higher capability to absorb impact energy when glass plies are located at the back face of the laminate. A detailed fractographic analysis by means of X-ray microCT and a FE model was included to explain such differences.

2022-01-01T00:00:00Z Rodríguez-Martín, Manuel Domingo, Rosario ribeiro, joao http://hdl.handle.net/10366/159033 2025-04-30T20:18:24Z 2024-05-28T00:00:00Z

This study aims to investigate the scientific impact of additive manufacturing in recent years, considering its evolution as an Industry 4.0 technology and also in the current context of Industry 5.0. For this aim, advanced statistics and scientometric tools have been used. Design/methodology/approach – This study aims to explore the trends and impacts of additive manufacturing, focusing on its evolution and its relationship with Industry 4.0 and 5.0. For this purpose, a scientometric study and a meta-analysis of data extracted from the scientific Scopus database have been carried out. R programming and specific bibliometric software have been used to conduct the research. Initially, the data were evaluated from various perspectives, including sources, topics and impact indexes, to assess trends derived from the volume of publications, the impact of sources and affiliations, as well as the production segmented by country and the relationships between authors from different countries. Subsequently, a meta-analysis on keywords has been carried out using two distinct clustering methodologies: link strength and fractionalization. The results obtained were compared to establish a specific taxonomy of the AM subtopics, considering AM as a single body of knowledge related to Industries 4.0 and 5.0 paradigms. The analyses carried out have shown the impact and strong evolution of additive manufacturing as a field of knowledge at the world level, both from the point of view of manufacturing processes and from the point of view of materials science. In addition, some differences have been detected depending on the country. As a result of the meta-analysis, four different subtopics have been detected, some of which are highly related to other technologies and approaches in Industries 4.0 and 5.0 paradigms. Additionally, it establishes a comprehensive taxonomy for AM research, serving as a foundational reference for future studies aimed at exploring the evolution and transformative impact of this technology.

2024-05-28T00:00:00Z