HAL Arts et Métiers
Not a member yet
14127 research outputs found
Sort by
Composites in high-pressure hydrogen storage: A review of multiscale characterization and mechanical behavior
No full textInternational audienc
Modeling of Streamer in Gas by FEM and Semi-Lagrangian Method
No full textInternational audienceDetermining the likelihood of occurrence, growth and extinction of partial discharges between two conductors is a key point when designing electrical devices such as transformers, electrical machines or busbars. The continuity equations governing both time-and position-dependence of charged particle densities allows to build the most comprehensive model of partial discharge development in gas. Known in the literature as fluid model, plasma model or even electrohydrodynamic model, it consists of set of drift-diffusionreaction type equations strongly coupled to Poisson's equation that still remains challenging to solve by means of FEM due to numerical instability. This paper deals with the modeling of spatio-temporal growth of partial discharge inside gas solved by means of FEM and stabilized by means of a semi-Lagrangian method
On the use of modal works of cutting forces to optimize machining conditions in the presence of vibrations
No full textInternational audienceThe use of Virtual Machining models may be a valuable approach in the designing stage of a machining operation as long as the models are sufficiently accurate. When vibration risks are suspected, stability analysis approaches to predict regenerative chatter phenomena are generally used. However, although these approaches, when applicable, allow efficient numerical optimization of the process around an operating point, they often require other strong assumptions such as neglecting transient phenomena or oversimplifying kinematics. On the other hand, time domain approaches with detailed matter removal modelling allow to monitor the continuous evolution of cutting conditions and represent various phenomena that the models can reproduce (regenerative chatter, forced vibrations, non-linear behaviours). The amount of data produced is, however, considerable and often costly to analyse. It may therefore be interesting to deduce, from these data, scalar indicators allowing easier and more relevant analysis of the simulation results.In this work, the modal work of the cutting forces upon the workpiece vibratory displacements is proposed as an indicator to discriminate different tool paths. A one degree of freedom theoretical problem and a face milling operation on extruded aluminum profiles extracted from automotive structural part are used to explain and show the relevance of such indicator
Erratum: Nonlinear interaction of an acoustical wave with a counter-propagating weak shock [J. Acoust. Soc. Am. 156 , 4085–4098 (2024)]
No full textInternational audienc
Open-Source Framework for Modeling the Evolution of Fiber Orientation
No full textInternational audienceModeling fiber orientation plays a crucial rule in predicting the behaviour of fiber reinforced thermoplastic materials. The equation that governs the evolution of the fiber orientation is hyperbolic in nature and requires handling fourth-order tensors, which are currently unavailable in OpenFOAM® .The current work explores the possibility of using OpenFOAM® and symbolic computation for modeling the evolution of fiber orientation. For this purpose, a functionObject was programmed to work as a plug-in solver for any OpenFOAM® incompressible flow solver, with the ability to compute the evolution of the second-order orientation tensor in a decoupled manner. Several fiber orientation models and closure relations available in the literature were implemented in the tool, which were verified by comparing their predictions with independent results obtained by numerically integrating the associated governing equations
Anticipatory muscle activations to coordinate balance and movement during motor transitions: A narrative review
No full textInternational audienceBackground: Maintaining balance while moving is vital for day-to-day activities. A key challenge in the comprehension of human movement is to determine how muscles contribute to balance-movement coordination. Motor transitions, defined as movements executed between two steady balance states, are particularly interesting phases to study balance-movement coordination because a large, discrete change in whole-body momentum may disturb balance. During voluntarily-initiated motor transitions, anticipatory muscle patterns provide the biomechanical conditions that are favourable to both maintaining balance and executing the movement.Research question: What are the mechanical consequences of anticipatory muscle activations for balance-movement coordination during voluntarily-initiated motor transitions?Methods: We review the biomechanical contributions of the anticipatory muscle activations identified in the literature during four types of voluntarily-initiated motor transitions, through the prism of three balance mechanisms (‘moving the centre of pressure (CoP)’, ‘counter-rotating segments’, and ‘applying new external force(s)’). In particular, we investigate how anticipatory muscle activations modulate whole-body centre of mass acceleration.Results:We show that the mechanical consequences of anticipatory muscle activations have been extensively described, but mainly using the ‘moving the CoP’ mechanism. Unlike their role during steady balance states, both ‘moving the CoP’ and ‘applying new external force(s)’ mechanisms create a required mechanical instability during the anticipatory phase of motor transitions. The ‘counter-rotating’ mechanism may act as a stabiliser during motor transitions, but additional research is needed to clarify this assumption.Significance: This review establishes that muscle activation processes have different mechanical consequences for balance-movement coordination during the anticipatory phases of motor transitions, compared to steady balance states. Because the mechanical instability that is created can lead to falls, a better understanding of the mechanisms underlying motor transitions is needed to enable the design of more effective fall prevention programs and/or devices for population with balance deficits
Adaptive Spatial Lattice Manufacturing (ASLM): A novel approach to efficient lattice structure production
No full textInternational audienceAdaptive Spatial Lattice Manufacturing (ASLM) represents a groundbreaking method for fabricating lattice structures by leveraging AI-driven robotic laser welding. Unlike traditional additive manufacturing techniques, ASLM corresponds to a direct assembly of solid rods, by welding, offering remarkable benefits in energy efficiency, dimensional accuracy, and scalability. This paper introduces the ASLM process, detailing its computational design principles, build mechanics, and material compatibility using AISI 316L stainless steel. Through mechanical characterization and finite element analysis, the structural performance of ASLM-produced lattices was evaluated, highlighting the predictability and reliability of their mechanical properties. Key findings demonstrate ASLM's capability to address critical limitations of conventional additive manufacturing methods, such L-PBF, LMD or EBM, while producing robust, scalable, and efficient designs. Challenges, including localized heat-affected zones and internal stress management, are also discussed, along with future prospects for multi-material integration and industrial applications in aerospace, construction, and beyond. ASLM establishes a transformative path for lattice manufacturing and advances the integration of architectured materials in diverse engineering domains.</div
From surveys to simulations: Integrating Notre-Dame de Paris' buttressing system diagnosis with knowledge graphs
No full textInternational audienceThe assessment of structural safety and a thorough understanding of buildings' structural behavior are critical to enhancing the resilience of the built environment. Cultural Heritage (CH) buildings present unique diagnosis challenges due to their diverse designs and construction techniques, often requiring attention during maintenance or disaster relief efforts. However, collaboration across CH and Architecture, Engineering, and Construction (AEC) fields is hindered by increasing information complexity and prolonged feedback loops. This paper introduces a methodological approach utilizing Knowledge Graph technologies to integrate structural diagnosis information and processes. The approach is applied to the diagnosis of the Notre-Dame de Paris buttressing system, demonstrated through a proof-of-concept knowledge system. By leveraging Knowledge Graph functionalities, insights are derived from the spatialization and provenance of mechanical phenomena, including observed or simulation-predicted cracks in mortar-bound masonry
Multi-dimensional measurement of mental workload in industrial context: an experiment in the field of helicopter maintenance
No full textInternational audienceAssessing mental workload is essential for optimizing the design of complex systems, particularly in aeronautical maintenance, where operators' activities serve as a crucial safety barrier to ensure optimal system safety levels. One of the roles of human factors in maintainability is, therefore, to anticipate maintenance activities and human behavior from the start of the design cycle. This study pursues a dual objective: firstly, to identify relevant for evaluating mental workload in an industrial maintenance environment, and secondly, to determine which of these indicators correlate with performance degradation. Ten participants performed five maintenance tasks of varying complexity on a helicopter, involving the removal, installation of components and a detailed inspection. Subjective measures (NASA-TLX), performance metrics (completion time), and cardiovascular data (heart rate, heart rate variability) were analyzed. We observed longer completion times and higher NASA-TLX scores for complex maintenance conditions. Regarding cardiovascular data, the results in the time domain of heart rate variability follow a similar trend compared to two other types of measurements. These results will be discussed in depth in this article. This study represents a further step in the multidimensional measurement of mental workload in maintenance within a realistic industrial context
Réalisation d'une analyse du cycle de vie d'un système pile à hydrogène
No full textCette étude présente et analyse les impacts environnementaux associés à la fabrication et à l'utilisation d'un système à pile à hydrogène de 48 kW, en s'appuyant sur les principes de la méthode normée d'Analyse du Cycle de Vie (ACV).International audienceCette étude présente et analyse les impacts environnementaux associés à la fabrication et à l'utilisation d'un système à pile à hydrogène de 48 kW, en s'appuyant sur les principes de la méthode normée d'Analyse du Cycle de Vie (ACV). L'objectif est d'identifier et d'évaluer ces impacts en fonction des composants et des matériaux, tout en discutant des enjeux méthodologiques associés. Les résultats montrent que la pile à combustible (stack) est le principal contributeur au changement climatique, avec un impact représentant 65 %, contre respectivement 21 % pour la batterie et 14 % pour les auxiliaires.La comparaison de l'inventaire du stack avec une base de données issue de la littérature révèle des différences méthodologiques pouvant entraîner des écarts allant jusqu'à 41 % en termes d'émissions de dioxyde de carbone équivalent (CO₂ eq). Ces résultats soulignent la nécessité d'une harmonisation des pratiques en ACV. L'étude intègre également une première approche de la phase d'utilisation, fournissant une base pour de futures évaluations couvrant l'ensemble du cycle de vi