This thesis describes the variety and the width of issues connected with crankshafts of combustion engines. It distinguishes different factors, which influence the shape and size of these crankshafts and the selected findings are then transferred into the design of crankshaft for the particular engine. The thesis also presents coherent description of application of topology optimization to the particular crankshaft and also different, more complex design procedures leading to the optimal shape of crankshaft are afterwards suggested. Quality of such a design is then verified by comparative analysis of fatigue of the crankshaft.

Grâce à la fabrication additive, il est aujourd'hui possible de fabriquer de nouvelles géométries. Les perspectives offertes par les moyens de fabrications conventionnelles et additives sont très différentes. Des propositions de design très contraintes peuvent devenir beaucoup plus libres avec la fabrication additive. Cette liberté qu'elle offre fait émerger une multitude de possibilités. Dans ce manuscrit, nous nous sommes focalisés sur un type particulier de structures (les octetruss) ainsi que sur les moyens de fabrication EBM (Electron Beam Melting) de la société ARCAM. Les travaux présentés dans cette thèse ont été réalisés au sein des laboratoires G-SCOP et SIMAP ainsi qu'en partenariat avec l'entreprise POLY-SHAPE. Ce manuscrit est articulé autour de trois principaux points.Il s'agit tout d'abord de faire émerger des structures treillis lors du processus de conception. Pour cela, deux approches existantes sont détaillées. La première met en œuvre l'optimisation topologique et la seconde s'appuie sur le concept de matériau équivalent. Ensuite deux méthodologies permettent de faire émerger des zones dans lesquelles l'intégration de structures treillis est adaptée. La première consiste à réaliser les différentes zones en s'appuyant sur un champ de contraintes issu d'un calcul Eléments Finis, la seconde se base sur un résultat d'optimisation topologique pour établir les différentes zones. Cette seconde méthodologie est appliquée à un cas d'étude industriel.Ensuite nous étudions comment remplir les différentes zones avec des structures treillis adaptées en nous focalisant tout d'abord sur leur génération. Un accent particulier est porté sur l'intersection des différents barreaux par la mise en place de sphères. Une méthodologie permettant de générer des arrondis est également proposée. Une étude est menée sur l'ensemble des paramètres et informations à considérer pour intégrer une structure treillis à une zone donnée. Cette étude conduit à une proposition de méthodologie qui est appliquée à un cas d'étude industriel.Enfin, les aspects liés à la fabrication sont pris en compte. Pour cela, nous considérons différentes limites du moyen de fabrication EBM pour des structures treillis comme les dimensions maximales réalisables ou les problématiques thermiques. Une étude consistant à prédire la dépoudrabilité des pièces est réalisée. Enfin, des essais mécaniques sont effectués. Nos résultats sont comparés à ceux obtenus dans d'autres travaux. L'impact des arrondis sur le comportement mécanique d'une pièce est discuté. / Thanks to additive manufacturing, it is now possible to manufacture new geometric shapes. The prospects offered by the methods of conventional and additive manufacturing are very different. Highly constrained design proposals can become much freer with additive manufacturing. The freedom it offers brings forward a multitude of possibilities. In this manuscript, we focused on a particular type of structures (the octetruss) as well as the use of EBM (Electron Beam Melting) of ARCAM as a means of manufacturing. The work presented in this thesis was carried out in the laboratories G-SCOP and SIMAP as well as in partnership with the company POLY-SHAPE. This manuscript focuses on three main points.The first of which is the action of emergence of lattice structures during the design process. For this, two existing approaches are detailed. The first uses topological optimization and the second is based on the concept of equivalent material. Following these, there are two methodologies used to identify areas in which the integration of lattice structures is possible and appropriate. The first consists of creating the different zones by relying on a stress field resulting from a finite element calculation, the second establishes the different zones using a topological optimization result. This second methodology is applied to an industrial case study.Secondly, we study how to fill the different areas with appropriate lattice structures by focusing first on their generation. Particular emphasis is placed on the intersection of the various bars by the establishment of spheres. A methodology for generating rounded-shape is also proposed. A study is carried out on all the parameters and information in order to integrate a lattice structure to a given area. This study leads to a proposed methodology that is applied to an industrial case study.Finally, aspects related to manufacturing are taken into account. For this, we consider different limits of the EBM manufacturing and what they mean for lattice structures; such as maximum achievable dimensions or thermal problems. A study to predict powder removal in order to extract the fabricated structure is performed. Mechanical tests are carried out. Our results are compared to those obtained in other works. The impact of curve on the mechanical behavior of a product is discussed.

Proposed in this thesis is a methodology to enable yacht designers to develop innovative structural concepts, even when the loads experienced by the yacht are highly uncertain, and has been implemented in sufficient detail to confirm the feasibility of this new approach. The new approach is required because today??s yachts are generally lighter, getting larger and going faster. The question arises as to how far the design envelope can be pushed with the highly uncertain loads experienced by the structure? What are the effects of this uncertainty and what trade-offs in the structural design will best meet the overall design objectives? The new approach provides yacht designers with a means of developing innovative structural solutions that accommodate high levels of uncertainty, but still focus on best meeting design objectives constrained by trade-offs in weight, safety and cost. The designer??s preferences have a large, and not always intuitive, influence on the necessary design trade-offs. This in turn invites research into ways to formally integrate decision algorithms into knowledge-based design systems. A lean and robust design system has been achieved by developing a set of tools which are blanketed by a fuzzy decision algorithm. The underlying tool set includes costing, material optimisation and safety analysis. Central to this is the innovative way in which the system allows non-discrete variables to be utilized along with new subjective measures of structural reliability based on load path algorithms and topological (shape) optimisation. The originality in this work is the development of a knowledge-based framework and methodology that uses a fuzzy decision making tool to navigate through a design space and address trade-offs between high level objectives when faced with limited design detail and uncertainty. In so doing, this work introduces the use of topological optimisation and load path theory to the structural design of yachts as a means of overcoming the historical focus of knowledge-based systems and to ensure that innovative solutions can still evolve. A sensitivity analysis is also presented which can quantify a design??s robustness in a system that focuses on a global approach to the measurement of objectives such as cost, weight and safety. Results from the application of this system show new and innovative structural solutions evolving that take into account the designers preferences regarding cost, weight and safety while accommodating uncertain parameters such as the loading experienced by the hull.

Proposed in this thesis is a methodology to enable yacht designers to develop innovative structural concepts, even when the loads experienced by the yacht are highly uncertain, and has been implemented in sufficient detail to confirm the feasibility of this new approach. The new approach is required because today??s yachts are generally lighter, getting larger and going faster. The question arises as to how far the design envelope can be pushed with the highly uncertain loads experienced by the structure? What are the effects of this uncertainty and what trade-offs in the structural design will best meet the overall design objectives? The new approach provides yacht designers with a means of developing innovative structural solutions that accommodate high levels of uncertainty, but still focus on best meeting design objectives constrained by trade-offs in weight, safety and cost. The designer??s preferences have a large, and not always intuitive, influence on the necessary design trade-offs. This in turn invites research into ways to formally integrate decision algorithms into knowledge-based design systems. A lean and robust design system has been achieved by developing a set of tools which are blanketed by a fuzzy decision algorithm. The underlying tool set includes costing, material optimisation and safety analysis. Central to this is the innovative way in which the system allows non-discrete variables to be utilized along with new subjective measures of structural reliability based on load path algorithms and topological (shape) optimisation. The originality in this work is the development of a knowledge-based framework and methodology that uses a fuzzy decision making tool to navigate through a design space and address trade-offs between high level objectives when faced with limited design detail and uncertainty. In so doing, this work introduces the use of topological optimisation and load path theory to the structural design of yachts as a means of overcoming the historical focus of knowledge-based systems and to ensure that innovative solutions can still evolve. A sensitivity analysis is also presented which can quantify a design??s robustness in a system that focuses on a global approach to the measurement of objectives such as cost, weight and safety. Results from the application of this system show new and innovative structural solutions evolving that take into account the designers preferences regarding cost, weight and safety while accommodating uncertain parameters such as the loading experienced by the hull.

Tesis por compendio / [ES] Esta tesis explora enfoques innovadores para la optimización estructural, abarcando una variedad de algoritmos de optimización comúnmente utilizados en el campo. Se centra específicamente en la optimización de forma (SO) y la optimización de topología (TO). La primera contribución de esta tesis gira en torno a garantizar y mantener un nivel deseado de precisión durante todo el proceso de TO y la solución propuesta. Al establecer confianza en los componentes sugeridos por el algoritmo de TO, nuestra atención puede centrarse en la siguiente contribución. La segunda contribución de esta tesis tiene como objetivo establecer una comunicación efectiva entre los algoritmos de TO y SO. Para lograr esto, nuestro objetivo es convertir directamente la distribución óptima de materiales propuesta por el algoritmo de TO en geometría. Posteriormente, optimizamos la geometría utilizando algoritmos de SO. Facilitar una comunicación fluida entre estos dos algoritmos presenta un desafío complejo, que abordamos proponiendo una metodología basada en aprendizaje automático. Este enfoque busca extraer un número reducido de modos geométricos que pueden servir como parametrización para la geometría, lo que permite su optimización mediante algoritmos de SO. Por último, la tercera contribución recoge algunas de las ideas previas y las lleva un paso hacia delante. La metodología propuesta tiene como objetivo derivar nuevos componentes a través de enfoques basados en el conocimiento existente en lugar de depender únicamente de procesos de TO basados en la física. Sostenemos que este conocimiento se puede obtener del histórico de diseños empleados por una determinada empresa, ya que retienen un valioso conocimiento inmaterial. Esta metodología también se basa en algoritmos de aprendizaje automático, pero también consideramos técnicas para analizar datos de alta dimensionalidad y estrategias de interpolación más adecuadas. / [CA] Aquesta tesi explora enfocaments innovadors per a l'optimització estructural, abastant una varietat d'algorismes d'optimització comunament utilitzats en el camp. Se centra específicament en l'optimització de forma (SO) i l'optimització de topologia (TO). La primera contribució d'aquesta tesi gira entorn de garantir i mantenir un nivell desitjat de precisió durant tot el procés de TO i la solució proposada. En establir confiança en els components suggerits per l'algorisme de TO, la nostra atenció pot centrar-se en la següent contribució. La segona contribució d'aquesta tesi té com a objectiu establir una comunicació efectiva entre els algorismes de TO i SO. Per a aconseguir això, el nostre objectiu és convertir directament la distribució òptima de materials proposta per l'algorisme de TO en geometria. Posteriorment, optimitzem la geometria utilitzant algorismes de SO. Facilitar una comunicació fluida entre aquests dos algorismes presenta un desafiament complex, que abordem proposant una metodologia basada en aprenentatge automàtic. Aquest enfocament busca extreure un nombre reduït de maneres geomètriques que poden servir com a parametrització per a la geometria, la qual cosa permet la seua optimització mitjançant algorismes de SO. Finalment, la tercera contribució recull algunes de les idees prèvies i les porta un pas cap endavant. La metodologia recomanada té com a objectiu derivar nous components a través d'enfocaments basats en el coneixement existent en lloc de dependre únicament de processos de TO basats en la física. Sostenim que aquest coneixement es pot obtenir de l'històric de dissenys emprats per una determinada empresa, ja que retenen un valuós coneixement immaterial. Aquesta metodologia també es basa en algorismes d'aprenentatge automàtic, però també considerem tècniques per a analitzar dades d'alta dimensionalitat i estratègies d'interpolació més adequades. / [EN] This thesis explores innovative approaches for structural optimization, encompassing a variety of commonly used optimization algorithms in this field. It specifically focuses on shape optimization (SO) and topology optimization (TO). The first contribution of this research revolves around ensuring and maintaining a desired level of accuracy throughout the TO process and the proposed solution. By establishing confidence in the suggested components of the TO algorithm, our attention can then shift to the subsequent contribution. The second contribution of this thesis aims to establish effective communication between TO and SO algorithms. To achieve this, our goal is to directly convert the optimal material distribution proposed by the TO algorithm into geometry. Subsequently, we optimize the geometry using SO algorithms. Facilitating seamless communication between these two algorithms presents a non-trivial challenge, which we address by proposing a machine learning-based methodology. This approach seeks to extract a reduced number of geometric modes that can serve as a parameterization for the geometry, enabling further optimization by SO algorithms. Lastly, the third contribution builds upon the previous idea, taking it a step forward. The proposed methodology aims to derive new components through knowledge-based approaches instead of relying solely on physics-based TO processes. We argue that this knowledge can be acquired from the historical designs employed by a given company as they retain invaluable immaterial know-how. This methodology also relies on machine learning algorithms, but we also consider techniques for analyzing high-dimensional data and more suitable interpolation strategies. / The authors gratefully acknowledge the financial support of Conselleria d’Educació, Investigació, Cultura i Esport, Generalitat Valenciana, project Prometeo/2016/007, Prometeo/2021/046 and CIAICO/2021/226. Ministerio de Economía, Industria y Competitividad project DPI2017-89816-R and Ministerio de Educación FPU16/07121. / Muñoz Pellicer, D. (2024). Development of Hybrid Optimization Techniques of Mechanical Components Employing the Cartesian Grid Finite Element Method [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/202661 / Compendio