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Winter sports have significantly developed in the last century. Among others, skiing is a winter-sport branch in which the equipment makes the difference in the performances. While in the beginning of the last century skis were simply made of wood, nowadays the increasing demand of performances and weight reduction has promoted the adoption of composite materials. However, no significant progress has been made in the engineering approach to design such equipment which are very often still designed on the basis of several physical prototypes and trials. This is particularly true in the niche sector of ski mountaineering, where the production batches are significantly smaller with respect to those of alpine skis and at the same time the weight reduction plays a determinant role. In this context, finite elements analysis (FEA) could represent an important tool to shorten the development times and costs leading to a more effective design process. The aim of this research is the development of an accurate virtual model of an existing mountaineering ski, capable of reproducing the behavior of the real component under operation. A preliminary characterization of all the materials used for the different layers of the ski was performed via tensile tests on flat dog-bone-shaped samples in combination with digital image correlation (DIC) techniques. Samples were laser cut from sheets. The tensile tests were performed in the two principal directions for each material. In combination with DIC, these tests allowed us to estimate the four in-plane (XY) elastic properties, namely, the two elastic modules, the shear module, and the Poisson ratio (Ex, Ey, Gxy, &nu, xy). The DIC acquisitions were elaborated with the free software GOM-Correlate. The digital model of the ski was created and simulated in an open-source environment: Code_Aster/Salome-Meca. The reason for using an open-source software is the possibility to parallelize the calculation without restrictions due to licenses and to customize the code according to the specific problem of interest. These aspects underline the potential of open-source software to improve the design process. The results of the simulations were compared with the response of the real ski in a three-point bending and a torsion-bending tests. Differences of 2.5%&ndash, 10% with respect to the real ski were observed for the different modeling techniques. Moreover, the validated virtual model of the ski was used to study the behavior of the ski when interacting with the snow for different roll angles and loads.

Winter sports have significantly developed in the last century. Among others, skiing is a winter-sport branch in which the equipment makes the difference in the performances. While in the beginning of the last century skis were simply made of wood, nowadays the increasing demand of performances and weight reduction has promoted the adoption of composite materials. However, no significant progress has been made in the engineering approach to design such equipment which are very often still designed on the basis of several physical prototypes and trials. This is particularly true in the niche sector of ski mountaineering, where the production batches are significantly smaller with respect to those of alpine skis and at the same time the weight reduction plays a determinant role. In this context, finite elements analysis (FEA) could represent an important tool to shorten the development times and costs leading to a more effective design process. The aim of this research is the development of an accurate virtual model of an existing mountaineering ski, capable of reproducing the behavior of the real component under operation. A preliminary characterization of all the materials used for the different layers of the ski was performed via tensile tests on flat dog-bone-shaped samples in combination with digital image correlation (DIC) techniques. Samples were laser cut from sheets. The tensile tests were performed in the two principal directions for each material. In combination with DIC, these tests allowed us to estimate the four in-plane (XY) elastic properties, namely, the two elastic modules, the shear module, and the Poisson ratio (Ex, Ey, Gxy, νxy). The DIC acquisitions were elaborated with the free software GOM-Correlate. The digital model of the ski was created and simulated in an open-source environment: Code_Aster/Salome-Meca. The reason for using an open-source software is the possibility to parallelize the calculation without restrictions due to licenses and to customize the code according to the specific problem of interest. These aspects underline the potential of open-source software to improve the design process. The results of the simulations were compared with the response of the real ski in a three-point bending and a torsion-bending tests. Differences of 2.5%–10% with respect to the real ski were observed for the different modeling techniques. Moreover, the validated virtual model of the ski was used to study the behavior of the ski when interacting with the snow for different roll angles and loads.

The development process of mountaineering skis is characterized by a rapid design phase due to the continuous changes in materials, customer’s requirements and manufacturing processes. Nowadays, this type of ski is still characterized by a design process based on a basilar trials and error technique. Finite Elements Analysis (FEA) could introduce a different approach to overcome main disadvantages, such as time, of this actual design method. For this reason, the main purpose of this work is centered on the development of a reliable FE model of an existing mountaineering ski, capable to forecast the mechanical behavior of the real tool. Firstly, all mechanical properties of materials that were composing the ski were characterized. Tensile tests in the two principal directions were performed on flat dog-bones shaped specimens. Secondly, Digital Image Correlation (DIC) was combined with results obtained from tensile tests in order to approximate the four in-plane (XY) elastic properties, namely, the two elastic modules, the shear module and the Poisson ratio (Ex, Ey, Gxy, νxy). Results of the cross-correlation process were after checked with the help of numerical simulations. FEA simulations were reproducing the tensile-tests configuration. Finally, geometry, mesh and simulations-run of the ski were performed in the open source environment Code_Aster/Salome-Meca. The results of simulations of the ski were compared with the response of the real ski in three-point bending tests. Differences of 2.5%-10% with respect to the real ski were observed for the different modelling techniques.

A crescente aposta em fontes energéticas renováveis e alternativas motiva o desenvolvimento de novos métodos e técnicas de aproveitamento energético. Como tal, novas estruturas de geração de energia são criadas e/ou melhoradas. A energia eólica offshore, em particular, foi alvo de estudo nesta dissertação, pelo seu carácter inovador e de aplicação incipiente em Portugal, que conta apenas com o projecto Demogravi3® da EDP®. O foco principal da dissertação são as fundações dos aerogeradores, cuja aplicabilidade é função das características batimétricas, climatéricas e do solo de fundação. O estudo incide sobre as fundações por gravidade, aplicáveis a batimetrias superiores a 30 m, acompanhando assim a motivação nacional em aproveitar este recurso a uma distância confortável da costa portuguesa. Avalia-se a capacidade de um solo marinho ao largo de S. Pedro de Muel, na costa oeste portuguesa, em acomodar a instalação de um aerogerador com fundação por gravidade nas batimétricas de 50 m. Procede-se, primeiramente, a uma caracterização física e mecânica da área em estudo. Em seguida, com a quantificação das cargas às quais o aerogerador vai estar submetido e que serão transmitidas ao solo marinho, realiza-se uma modelação tridimensional com recurso ao software open-source Salome-Meca, que utiliza o Método dos Elementos Finitos. Analisam-se neste programa a distribuição de tensões, os assentamentos totais e diferenciais, bem como a plastificação do solo de fundação. Analiticamente, complementando e validando os resultados da modelação, avaliaram-se os assentamentos, tombamento da estrutura, resistência do solo ao carregamento e ao deslizamento do aerogerador. Conclui-se que, para o material arenoso e cascalhento que constitui o solo em estudo, há viabilidade de instalação do aerogerador com uma margem de segurança alta no que diz respeito à capacidade portante e à resistência ao deslizamento e também aos outros tipos de instabilização mencionados.

En el estudio del comportamiento de una determinada estructura hay que tener en cuenta las características del material del que está formada y es difícil que los programas de cálculo tengan en su base de datos las características del comportamiento de todos los materiales. Para solucionar este problema, existe MFRONT, que se trata de una herramienta con licencia LGPL o, dicho de otra forma, de software libre, destinada a la generación de código para el estudio de los materiales. In the study of the behaviour of a given structure, it is necessary to take into account the characteristics of the material of which it is formed and it is difficult for the calculation programs to have in their database the characteristics of the behaviour of all the materials. To solve this problem, there is MFRONT, which is a LGPL licensed tool or, in other words, free software, aimed at generating code for the study of materials. En l'estudi del comportament d'una determinada estructura cal tenir en compte les característiques del material del que està formada i és difícil que els programes de càlcul tinguen en la seua base de dades les característiques del comportament de tots els materials. Per a solucionar aquest problema, existeix MFRONT, que es tracta d'una eina amb llicència LGPL o, dit d'una altra forma, de programari lliure, destinada a la generació de codi per a l'estudi dels materials.

International audience; Salome-Meca est une plate-forme dédiée à la simulation en mécanique. Son ambition est de fournir un environnement logiciel permettant de réaliser la chaîne complète de calcul CAO, maillage, calcul, visualisation des résultats.

Con la evolución en el uso de los materiales y técnicas de diseño se están construyendo estructuras cada vez más esbeltas y flexibles. Por sus características, estas estructuras requieren técnicas computacionales avanzadas para la evaluación del Estado Límite de Fatiga. En sus recientes recomendaciones, el International Institute of Welding propone distintos enfoques para abordar el cálculo del daño por fatiga, pudiéndose diferenciar los enfoques basados en las curvas S-N y en la Mecánica de la Fractura. La atención se concentra en la evaluación del daño por fatiga en uniones metálicas, estudiando en detalle el análisis de un puente de ferrocarril de alta velocidad donde se comparan los distintos métodos propuestos. Para realizar todos los cálculos se utilizará el entorno de software libre desarrollado por Electricidad de Francia conocido como Salomé-Meca. El interés de este proyecto radica en la evaluación de las posibilidades que ofrece el software libre para la evaluación del daño por fatiga, aspecto poco explorado en la literatura actual. Como primera aproximación al software se han realizado varios modelos de calibración, comprobando la capacidad para la evaluación del daño por fatiga según los distintos enfoques. A continuación, se ha propuesto un puente de ferrocarril para su estudio, determinando un detalle concreto donde se evaluará el daño por fatiga. Se llevarán a cabo análisis basados en las tensiones determinadas en el Hot-Spot y en el Notch, ambos enmarcados en el uso de las curvas S-N. Por otra parte, se llevará a cabo un análisis basado en la Mecánica de la Fractura. Como conclusión se comprueba la posibilidad de evaluar todos los métodos propuestos para el análisis de fatiga mediante el software Salomé-Meca, destacando las ventajas del método basado en la Mecánica de la Fractura frente a los métodos basados en las curvas S-N., The new Recommendations for fatigue analysis developed by the International Institute of Welding (IIW-1823-0, december 2008) have introduced new concepts and evaluation techniques to verify the Fatigue Limit State. The SN-curves and the direct crack growth based on Fracture Mechanics have been updated with new curves, post-welding curves, and requirements for numerical methodsd. Two SN methods have been included: the hot-spot stress and the notch stress. The three referenced methods requiere numerical solutions, for which fine meshes for accurate evaluation are required. In this work the three basic techniques are explored in the context of a particular tubular welded connetion in a steel bow-string bridge for high-speed train. Fatigue damage index is evaluated by SN curves (hot-spot or notch stress approach) and by crack propagation (Paris law) under variable amplitude load. The stress history for 50 or 100 years comes from the direct simulation of a high-speed train traversing the bridge. The Rainflow cycle counter algorithm has been used to identify the constant-amplitude ranges and number of cycles, for both hot-notch stress or stress intensity factors at crack tips. The three evaluation techniques have been compared and contrasted. It has been observed that, as pointed in the literature, notch stress curves provides more optimistic prediction, in contrast with SN evaluation based on hot-spot stress or crack propagation. This work suggests the revision of notch-stress curve and the limitations of FAT 200 or FAT 225 curves. All the numerical tests are carried out with software Code-Aster, from Electricitè de France. Through extensive tests, it is shown that Code-Aster is provided with adequate tools (such as specific error estimators for crack in X-FEM and mesh refinement) to obtain the fatigue verifications according to IIW requirements. Fatigue, notch stress, hot spot point, fracture mechanics, SN curves, Rainflow analysis, DNV, fatiga, International Institute of Welding, Palmgren-Miner, damage index, crack propagation, Salome-Meca, Code-Aster, Proyecto Fin de Carrera de la Univ. de Granada, Departamento de Mecánica de Estructuras

Salome-Meca est une plate-forme dédiée à la simulation en mécanique. Elle fournit un environnement logiciel permettant de réaliser la chaîne complète de calcul CAO, maillage, calcul, visualisation des résultats. Deux exemples d’utilisation sont présentés : une étude thermo-mécanique d’une enceinte de confinement et une étude thermo-hydraulique d’un té de mélange.