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eCAD-Net: Editable Parametric CAD Models Reconstruction from Dumb B-Rep Models Using Deep Neural Networks
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Comparaison des modèles de correction de la non-linéarité des trajets de déformation lors de la caractérisation des CLF
No full textInternational audienceThe Forming Limit Diagram (FLD) is a widely used tool in sheet metal forming to predict the formingbehavior of sheet metal. The experimentally determined FLD depend to some extent on the stretchingtests used, like the Nakajima or Marciniak tests. Numerous correction models have been proposedover the last 50 years for the effects of the non-linear strain path, curvature, or normal stress. Thepurpose of this paper is to summarize and compare the mathematical formulations and properties ofexisting correction models for the non-linear strain path influence on the Nakajima test results. Itappears from the analysis that a large number of the available models share identical hypotheses andresults, which simplifies and further guides the user’s efforts in selecting the adequate correctionmodel.La courbe limite de formage (CLF) déterminée expérimentalement dépend dans une certaine mesuredes essais utilisés, comme les essais Nakajima ou Marciniak. De nombreux modèles de correction ontété proposés au cours des 50 dernières années pour prendre en compte les effets liés aux trajets dedéformation non linéaires, à la courbure ou à la contrainte normale. Le but de cet article est derésumer et de comparer mathématiquement les modèles de correction traitant de l'influence deschemins de déformation sur les CLF issues d’essais de type Nakajima. Il ressort de l'analyse qu'ungrand nombre de modèles disponibles partagent des hypothèses et des résultats identiques, ce quisimplifie et oriente davantage les efforts de l'utilisateur dans le choix du modèle de correctionadéquat
Spatialization, fusion and enrichment of Multimodal Imaging for Interdisciplinary Digital Heritage Studies
No full textContributors: A. Pamart (AP), L. De Luca (LDL), P. Veron (PV).CRediT (https://credit.niso.org/): Conceptualization : AP; Data curation: AP; Formal analysis : AP; Funding acquisition : LDL; Investigation: AP; Methodology : AP, LDL, PV; Project administration: LDL; Resources : AP; Software : AP; Supervision : LDL, PV;Validation : AP; Visualization : AP; Writing – original draft : AP;Writing – review & editing : AP.International audienceDigital Heritage (DH) has emerged as a dynamic and crucial concept for the future of Heritage Science (HS), at the crossroads of interdisciplinary fields. Nowadays, methods, tools and technologies for capturing reality play a predominant role in Cultural Heritage (CH) documentation framework. Indeed, the 2D/3D imaging and digitization techniques are massively employed today to survey, document, and study heritage artifacts. They offer numerous perspectives and avenues for investigation to enhance shared knowledge around heritage conservation and restoration. However, as the need for digital expertise expends in both scope and number, these various methods employed face the challenge of multimodality. This concept is at the core of this research, it is understood and justified by the growing need to cooperate with various digital resources (originating from multiple sensors, scales of observation, spectral or temporal layers) in order to feed and cross expertise. This paper explores 2D and 3D digitization strategies to enhance the potential of multimodal studies. The main contributions develop data-driven methods improving Spatialization, Fusion and Enrichment stages. Different types of approaches are proposed, aiming to better articulate the instrumental, computational and analytical phases in order to increase the informative potential of multi-source 2D/3D modelling. The strategy is demonstrated by a series of works and experiments enabling to construct and explore enriched multimodal data sets. The proposal offers reasoned and pragmatic solutions while the discussion anticipates emerging challenges such as semantic technologies, open science, artificial intelligence, and digital sobriety
Coupled crystal plasticity-cohesive zone modeling of rock salt viscoplasticity
No full textInternational audienceRock salt, owing to its viscoplastic behavior and structural integrity under high pressure, is a promising candidate for safe and large-scale underground energy storage. This study presents a comprehensive numerical framework for modeling the viscoplastic deformation of rock salt, accounting for both intragranular and grain boundary (GB) deformation mechanisms. Intragranular deformation is modeled using a crystal plasticity approach governed by a powerlaw relation, capturing the activity of crystallographic slip systems. Concurrently, a cohesive zone model (CZM) is introduced to simulate grain boundary sliding (GBS) and opening via a rate-dependent traction-separation law. This modeling strategy enables a detailed analysis of the coupled interplay between crystal plasticity and intergranular decohesion phenomena
Continuum defect mechanics and Fast Fourier transform (FFT) based numerical implementations with some applications
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In situ porosity imaging with synchrotron X-ray Tomography during laser rescanning of Zr-based metallic glass by Laser Powder Bed Fusion
No full textInternational audienceWhen laser powder bed fusion (LPBF) is applied to bulk metallic glasses rather than traditional crystalline alloys, one has to avoid conditions that could cause crystals to form. To achieve a balance between the porosity content and devitrification in the heat affected zone, it is common practice to process such material with a thin layer thickness, and thereby reduce the laser power necessary for melting. In this manufacturing regime, lack-of-fusion defects typically subsist. This work investigates how laser rescanning can densify metallic glasses while still ensuring their amorphous nature. Synchrotron X-ray Computed Tomography during LPBF allows imaging in situ the pores upon the glass construction. This non-destructive cutting-edge technique helps understanding the consolidation mechanism associated with rescanning and in particular its effect on layer surface roughness and the homogeneity of the powder recoating. Applied to the well-established Zr-Cu-Al-Nb grade, this work paves the way towards the adoption of less thermally stable glasses for LPBF, and the control of defect distribution. In particular, it is revealed that the hatch spacing effect is of primary importance in the production of viscous materials such as glasses, and that laser rescanning allows the surface of the deposited layer to be smoothed, improving consolidation without associated crystallisation
Comparison of High-Energy Density and High-Power Density Batteries for an Electric Vehicle
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Thermo-elastic micromechanical modeling of tetragonal ZrO with a herringbone microstructure inherited from the cubic phase
No full textInternational audienceThe distribution of residual stresses at the crystal scale is investigated in several random polycrystalline aggregates of zirconia. The underlying stochastic model generates tetragonal crystals forming three-dimensional herringbone microstructures, originating from cooling an initial single cubic crystal at high temperatures followed by a solidstate phase transition. The obtained microstructures are constructed following crystallographic constraints in terms of variant selection, as well as twin and band boundary orientations. This stochastic modeling approach allows generating microstructures with twin domains of various aspect ratios, embedded in several Voronoi cells as observed when the phase transition starts simultaneously from different locations in the cubic crystal. Considering the transformation strain and the anisotropic elastic and dilation properties at the crystal scale, these microstructures are solved with the spectral (FFT) full-field method for pure thermal loading (cooling). Thermal dilation has a limited effect on the residual stress field, about one order of magnitude smaller than the transformation strain, even for a cooling of 1000°C. Normal stresses along the tetragonal crystal axes are in the order of a few GPa and proportional to the tetragonality of the zirconia crystal, except for a specific microstructure where stresses even vanish for infinite aspect ratios
A conceptual framework for sustainable value creation: a case study of a French ecovillage
No full textInternational audienceAwareness of planetary boundaries underscores the need for systemic changes to maintain Earth's habitability. Local initiatives, such as ecovillages, are pivotal in driving sustainable transitions by fostering innovative social and technical solutions. Ecovillages, designed to regenerate social and natural environments, provide models of sustainable living that address the harmful effects of human activities. However, there is limited research on how ecovillages can generate sustainable value (SV). Drawing on both theoretical and empirical approaches, this article introduces a conceptual framework for co-creating SV in ecovillages, integrating their ecosystems, territories, actors, resources, and capabilities. The framework considers three stages for creating SV in the early phases of the design process: understanding the ecovillage ecosystem, analyzing the territory, and generating an SV proposition for the local territory. A case study of a French ecovillage illustrates how the framework facilitates the generation of concrete sustainability projects. This article highlights the impact of understanding SV creation in ecovillages for researchers and practitioners working on local initiatives with strong sustainability paradigm. It addresses the gap in recognizing the role of integrating actors and resources as essential for the sustainable transitions of the local territory. Further studies could focus on testing this framework in other ecovillages to evaluate its practical effectiveness in generating sustainable projects
Body segment inertial parameters of children derived from a large database of 3D body scans
No full textInternational audienceBody segment inertial parameters (BSIPs) are critical for human movement analysis. However, child-specific BSIPs remains limited. This study aimed to develop regression models for BSIPs (mass, CoM-position, and moments of inertia) using 3D body scans from 688 children aged 2.9–12.7 years. A 3D scanning system was used to capture body surfaces as point clouds, which were automatically processed to generate segmented, personalized volumetric body meshes with embedded segment coordinate systems. These meshes were then used to compute 3D BSIPs, which were normalized (relative to body mass and corresponding segment length) and fitted by regression models separately for males and females. The regression models demonstrated high predictive accuracy for normalized mass and moderate-to-good accuracy for normalized CoM-positions and radii of gyration. Age-related changes were observed as reductions in normalized mass for the head-neck and abdomen, alongside increases for the thigh. Normalized CoM-positions shifted posteriorly for the abdomen, anteriorly for the thigh, and proximally for the forearm. Normalized radii of gyration declined across all directions, particularly for the hand and thigh. This work provides the first comprehensive BSIP regressions for a large, gender-balanced cohort of children up to 12 years old, addressing limitations in prior research with a fully automated approach. These regressions are expected to advance biomechanical modeling and enhance movement analysis in pediatric populations