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Dual Weighted Residual-driven adaptive mesh refinement to enhance biomechanical simulations
No full textInternational audienceThis chapter describes how a posteriori error estimates targeting a user-defined quantity of interest, using the Dual Weighted Residual (DWR) technique, can be easily applied for biomechanical simulations in current engineering practice. The proposed method considers a very general setting that encompasses complex geometries, model non-linearities (hyperelasticity, fluid-structure interaction) and multi-goal oriented techniques. The developments are substantiated with some numerical tests
Prise en compte du frettage dans la tenue mécanique d'un assemblage fretté-soudé pour une application nucléaire
No full textInternational audienceAdapter tubes are key elements that allow the passage of control mechanisms from the outside to theinside of the pressure vessel. They are shrunk fit and welded to the closure head. The interference fit setthe adapter tubes for the welding operation.Currently, mechanical justification only use the contribution of the welded part, ignoring the effect ofinterference fit. However, for a better understanding and to enhance margins, it is necessary to improvethe knowledge about this assembly.In literature, the mechanical strength of interference fit has been studied with the Coulomb’s frictionmodel. The maximum force can be calculated from the knowledge of the contact pressure and the frictioncoefficient at the interface. The aim of this paper is to compare results obtained from analytical andnumerical models on nominals and loaded applications in order to determine contact pressure and itsvariations.Les tubes adaptateurs représentent un assemblage clé de la centrale nucléaire en permettant le passagedes mécanismes de contrôle de la réaction nucléaire depuis l’extérieur de la cuve. Ils sont liés au cou-vercle de cuve par une liaison frettée-soudée. Le frettage des tubes permet de les mettre en position etde les maintenir lors de l’opération de soudage.Actuellement, lors des justifications mécaniques, la tenue de ces assemblages est intégralement prouvéepar la contribution de la soudure, ignorant l’apport du frettage. Cependant, dans un souci de compré-hension et d’amélioration des marges dans les études de conception, une connaissance plus fine de cesassemblages est exigée. La prise en compte du frettage dans l’évaluation de la tenue mécanique et deson évolution au cours du temps apparait comme un thème prometteur.Dans la littérature, la tenue des assemblages frettés est largement modélisée par un modèle de frotte-ment de Coulomb. Ce modèle estime l’effort d’arrachement du tube à partir de la connaissance de lapression de contact et du coefficient de frottement à l’interface. Cet article propose de comparer lesrésultats issus de modèles analytiques et numériques sur des applications nominales et de chargementafin de déterminer la pression de contact et ses variations
Design and Optimisation of a Vibrating Wing Insect-Size Air Vehicle with Lumped Parameter Models and Compliant Links
No full textInternational audienceAbstract This article presents the design of a microfabricated bio-inspired flapping-wing Nnano Aaerial Vvehicle (NAV), driven by an electromagnetic system. Our approach is based on artificial wings composed of rigid bodies connected by compliant links, which optimise aerodynamic forces though replicating the complex wing kinematics of insects. The originality of this article lies in a new design methodology based on a triple equivalence between a 3D model, a multibody model, and a mass/spring model (0D) which reduces the number of parameters in the problem. This approach facilitates NAV optimisation by using only the mass/spring model, thereby simplifying the design process while maintaining high accuracy. Two wing geometries are studied and optimised in this article to produce large-amplitude wing motions (approximately ), and enabling flapping and twisting motion in quadrature. The results are validated thanks to experimental measurements for the large amplitude and through finite element simulations for the combined motion, confirming the effectiveness of this strategy for a NAV weighing less than 40 mg with a wingspan of under 3 cm
Intégrer et optimiser une méthode pluridisciplinaire et collaborative permettant le déploiement du design centré sur l'utilisateur (UX) en entreprise.
No full textThis CIFRE thesis, conducted within the R&D center of Saint-Gobain, explores the integration of user-centered design (UX) into the product design process. It proposes a multidisciplinary and collaborative method, focusing on the early stages of the process, often referred to as the "fuzzy front end" due to their ambiguous and uncertain nature.The research begins with an assessment of Saint-Gobain's initial process. This process is analyzed and optimized to better integrate the UX approach. The first hypothesis of the thesis is that it is necessary to formalize a common and multidisciplinary process supported by a user-centered approach. This hypothesis is partially validated but reveals limitations, notably a lack of understanding of the process in a collaborative context, particularly during the early stages.To address these limitations, the thesis proposes a second hypothesis: it is necessary to physically materialize the early stages of the design process. This materialization takes the form of a trends laboratory, the Trends Lab, and an associated method, TSDT (Trends Selection, Development, and Transformation). The Trends Lab is a space dedicated to collaboration between designers, marketers, and engineers, allowing for the structuring and guiding of the early stages of the design process. The TSDT method is based on the steps of the SFA model (Scan, Focus, Act) and offers specific tools for each stage.The results show that the physical materialization of the early stages improves the understanding of the process and interdisciplinary collaboration. The developed tools, such as trend sheets and transformation templates, facilitate data collection and analysis, as well as the generation of innovative ideas. The Trends Lab also helps to disseminate a culture of innovation within the company and reinforce the legitimacy of the UX approach.In conclusion, this thesis makes significant contributions both scientifically and industrially. It proposes a tool-based and collaborative method to integrate UX into the product design process and demonstrates the importance of physically materializing the early stages to foster user-centered collaboration and innovation.Cette thèse CIFRE, réalisée au sein du centre de R&D de Saint-Gobain, se penche sur l'intégration du design centré-utilisateur (UX) dans le processus de conception de produits. Elle propose une méthode pluridisciplinaire et collaborative, en mettant l'accent sur les phases amont du processus, souvent qualifiées de "fuzzy front end" en raison de leur nature floue et incertaine.La recherche débute par un état des lieux du processus initial de Saint-Gobain. Ce processus est analysé et optimisé pour mieux intégrer l'approche UX. La première hypothèse de la thèse est qu'il est nécessaire de formaliser un processus commun et pluridisciplinaire supporté par une approche centrée-utilisateur. Cette hypothèse est partiellement validée, mais révèle des limites, notamment un manque de compréhension du processus dans un contexte de collaboration, en particulier lors des phases amont.Pour pallier ces limites, la thèse propose une seconde hypothèse : il est nécessaire de matérialiser physiquement les étapes amont du processus de conception. Cette matérialisation prend la forme d'un laboratoire de tendances, le Trends Lab, et d'une méthode associée, la TSDT (Trends Selection, Development, and Transformation). Le Trends Lab est un espace dédié à la collaboration entre designers, marketeurs et ingénieurs, permettant de structurer et de guider les phases amont du processus de conception. La méthode TSDT s'appuie sur les étapes du modèle SFA (Scan, Focus, Act) et propose des outils spécifiques pour chaque étape.Les résultats montrent que la matérialisation physique des étapes amont améliore la compréhension du processus et la collaboration interdisciplinaire. Les outils développés, tels que les fiches tendances et les templates de transformation, facilitent la collecte et l'analyse des données, ainsi que la génération d'idées innovantes. Le Trends Lab permet également de diffuser une culture d'innovation au sein de l'entreprise et de renforcer la légitimité de l'approche UX.En conclusion, cette thèse apporte des contributions significatives à la fois sur le plan scientifique et industriel. Elle propose une méthode outillée et collaborative pour intégrer l'UX dans le processus de conception de produits, et démontre l'importance de la matérialisation physique des étapes amont pour favoriser la collaboration et l'innovation centrée sur l'utilisateur
Le WAAM : synergie recherche - pédagogie
No full textInternational audienceLe WAAM : synergie recherche - pédagogi
Hybrid AC Shipboard Microgrid Time Delayed LFC and AVR Controllers Tuning Through Gazelle Optimization Algorithm and Real-Time HIL Implementation
No full textInternational audienceEfforts to reduce greenhouse gas emissions in maritime power networks have led to the integration of renewable energy resources into hybrid AC shipboard microgrid (hSMG) systems. However, challenges are introduced in maintaining voltage and frequency within acceptable limits due to the stochastic nature of power injection from renewable energy sources, the intermittent nature of the load due to the propulsion or the hotel loads and the sensors/communication link time delays. This article introduces for the first time a hardware-in-loop implementation of combining load frequency control and automatic voltage regulation within an autonomous hSMG comprising wave power generation, photovoltaic, diesel generator, proton exchange membrane fuel cell energy unit, battery energy storage system and flywheel energy storage system. The analysis also considers the significance of addressing time delays resulting from communication links between the sensors and the controllers. The stability of the hSMG model is assessed through comprehensive analysis under different scenarios and comparative performance of various controllers. The parameters of the controllers are fine-tuned using a recently developed bio-inspired approach, the Gazelle Optimization Algorithm. Furthermore, a sensitivity analysis of the best controller found is carried out. Experimental results demonstrate the resilience and effectiveness of the proposed frequency/voltage control approach
Influence of diameter and scan strategy on the geometrical, microstructural, and mechanical properties of small Inconel 625 L-PBF struts
No full textInternational audienceThe geometries, microstructures, and mechanical properties of vertically built Inconel 625 Laser Powder Bed Fusion (L-PBF) struts were investigated in this study. The influence of strut size (between 0.2 mm and 2 mm) and scan strategy was more specifically addressed. As-built struts exhibit satisfactory geometry and porosity rates, whatever the strut size and scan strategy. Classical columnar grains oriented parallel to the build direction (BD) were obtained, with a < 001 > // BD fiber texture only for the smaller struts (0.2 mm to 0.5 mm), due to the formation of a unique circular melt pool on the whole strut surface. At a smaller scale, the influence of the build strategy is also visible on solidification cells, whose average diameter decreases for outside-in strategies and larger hatching area ratios. The tensile strengths and hardness values are lower for the smaller diameter (0.3 mm) struts and for the inside-out strategies, suggesting the important role played by a finer sub-grain structure and a smaller crystallographic texture on the strengthening of Inconel 625 struts
Effects of occupant behaviour on head pitch rotation in a SAE Level 3 autonomous vehicle driving simulator
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Balance analysis of autistic children during beam walking
No full textInternational audienceAutism Spectrum Disorder (ASD) is characterised by persistent deficits in communication and social interaction, as well as restricted, repetitive patterns of behaviour, interests, or activities. Although not included among the diagnostic criteria, motor disorders are also part of the clinical phenotype of ASD, and their origins are largely under-researched (Mosconi et al., 2015). Among these motor disorders, specificities in postural control and gait initiation have been identified (Benchekri et al., 2023), suggesting that balance mechanisms are impacted by ASD. Walking on a narrow beam requires the ability to maintain balance with a reduced base of support (BoS) along the medio-lateral (ML) direction. When balance is challenged, humans can use various strategies to increase stability, such as increasing the size of the BoS to enhance the whole-body centre of mass (CoM) shifts and/or rotating segments to modulate whole-body angular momentum (AM) (Hof, 2007). To rely on the “extend the BoS” strategy is limited when walking on a beam. Authors have shown that the main stabilisation strategy during this type of task focuses on regulating the AM of different body parts (Chiovetto et al., 2018) and also that a significant active control is required to stabilise motion especially along the ML axis (Bauby & Kuo, 2000). Assuming that children with ASD exhibit unique balance characteristics in motor tasks, it is important to explore the extent of their particularities by analysing their performance during challenging balance tasks such as beam walking
On the atomistic origin of internal length scale in strain-gradient plasticity models: The case of grain boundary structures and energies
No full textInternational audienceThe mechanical behavior of polycrystalline materials is controlled by microstructural size effects such as grain size or precipitate size. Various models of strain gradient plasticity have been proposed to capture such size effects, many of which have incorporated geometrically-necessary dislocation (GND) densities to introduce characteristic internal lengths. Recent developments have focused on models that incorporate a GND density into the internal energy functional. In such models, one needs to physically justify the functional form chosen and quantify the inherent internal length parameter. Our present study aims at probing relevant forms and internal length values in the case of grain boundary (GB) atomistic structures and core energies. We use an atomistic-to-continuum crossover approach that predicts an atomistic structure dependent GB energy by molecular static simulations, which is then recovered at the continuum-level by using a strain gradient, atomistically informed, field dislocation mechanics fast Fourier transform model. This allows (i) delineating the atomistic structure of GBs using an equivalent Nye GND density, and (ii) capturing the associated continuous elastic fields in the GB core area. We probe (i) a generalized non-quadratic GND density dependent energy functional to account for the core energy of defects, and (ii) elucidate the contributions of core versus elastic energy to the overall GB excess energy. We investigate and discuss the possible relevant choices for the energy functional form, as well as the physical origin of the inherent internal length parameter and its dependence to the types of grain boundaries, atomistic structures, and spatial resolution