https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Sat, 07 Mar 2026 00:24:03 GMT 2026-03-07T00:24:03Z http://hdl.handle.net/10985/10917 Modélisation multi-échelle du comportement électrique de nano-composites Cu-Nb GU, T; HERVE-LUANCO, E; PROUDHON, H; THILLY, L; DUBOIS, J.-B.; LECOUTURIER, F; CASTELNAU, Olivier; FOREST, S Les fils composites nanostructurés et architecturés cuivre-niobium, qui sont de bons candidats pour la génération de champs magnétiques intenses, allient une limite d’élasticité élevée et une excellente conductivité électrique. Ils sont élaborés par co-déformation d’un assemblage composite Cu-Nb. La microstructure, multi-échelle, est formée de 853 motifs élémentaires de Cu-Nb de taille caractéristique nanométrique. Afin d’étudier le lien entre la conductivité électrique effective et la microstructure, deux méthodes d’homogénéisation sont appliquées : l’une, en champs moyens (modèle auto-cohérent généralisé), dans laquelle une microstructure formée de motifs co-cylindriques répartis aléatoirement est considérée, et l’autre, en champs complets (éléments finis), dans laquelle l’aspect périodique de la microstructure expérimentale est pris en compte. Les effets de la taille des constituants élémentaires (nm), de la température, ainsi que de la densité de dislocations, sur la conductivité locale sont considérés. Le caractère multi-échelle du matériau est pris en compte grâce à un processus itératif. Les conductivités effectives longitudinale et transversale obtenues avec les deux méthodes sont en excellent accord, montrant un moindre effet de la distribution des fibres sur ces propriétés. Ces résultats reproduisent également les données expérimentales disponibles. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/10917 2015-01-01T00:00:00Z GU, T HERVE-LUANCO, E PROUDHON, H THILLY, L DUBOIS, J.-B. LECOUTURIER, F CASTELNAU, Olivier FOREST, S Les fils composites nanostructurés et architecturés cuivre-niobium, qui sont de bons candidats pour la génération de champs magnétiques intenses, allient une limite d’élasticité élevée et une excellente conductivité électrique. Ils sont élaborés par co-déformation d’un assemblage composite Cu-Nb. La microstructure, multi-échelle, est formée de 853 motifs élémentaires de Cu-Nb de taille caractéristique nanométrique. Afin d’étudier le lien entre la conductivité électrique effective et la microstructure, deux méthodes d’homogénéisation sont appliquées : l’une, en champs moyens (modèle auto-cohérent généralisé), dans laquelle une microstructure formée de motifs co-cylindriques répartis aléatoirement est considérée, et l’autre, en champs complets (éléments finis), dans laquelle l’aspect périodique de la microstructure expérimentale est pris en compte. Les effets de la taille des constituants élémentaires (nm), de la température, ainsi que de la densité de dislocations, sur la conductivité locale sont considérés. Le caractère multi-échelle du matériau est pris en compte grâce à un processus itératif. Les conductivités effectives longitudinale et transversale obtenues avec les deux méthodes sont en excellent accord, montrant un moindre effet de la distribution des fibres sur ces propriétés. Ces résultats reproduisent également les données expérimentales disponibles. http://hdl.handle.net/10985/12554 Multiscale modeling of the anisotropic electrical conductivity of architectured and nanostructured Cu-Nb composite wires and experimental comparison GU, TANG; MEDY, J.-R; VOLPI, F; CASTELNAU, Olivier; FOREST, S; HERVE-LUANCO, E.; LECOUTURIER, F; PROUDHON, H; RENAULT, P.-O; THILLY, L Nanostructured and architectured copper niobium composite wires are excellent candidates for the generation of intense pulsed magnetic fields (> 90T) as they combine both high electrical conductivity and high strength. Multi-scaled Cu-Nb wires can be fabricated by accumulative drawing and bundling (a severe plastic deformation technique), leading to a multiscale, architectured and nanostructured microstructure providing a unique set of properties. This work presents a comprehensive multiscale study to predict the anisotropic effective electrical conductivity based on material nanostructure and architecture. Two homogenization methods are applied: a mean-field theory and a full-field approach. The size effect associated with the microstructure refinement is taken into account in the definition of the conductivity of each component in the composites. The multiscale character of the material is then accounted for through an iterative process. Both methods show excellent agreement with each other. The results are further compared, for the first time, with experimental data obtained by the four-point probe technique, and also show excellent agreement. Finally, the qualitative and quantitative understanding provided by these models demonstrates that the microstructure of Cu-Nb wires has a significant effect on the electrical conductivity Sun, 01 Jan 2017 00:00:00 GMT http://hdl.handle.net/10985/12554 2017-01-01T00:00:00Z GU, TANG MEDY, J.-R VOLPI, F CASTELNAU, Olivier FOREST, S HERVE-LUANCO, E. LECOUTURIER, F PROUDHON, H RENAULT, P.-O THILLY, L Nanostructured and architectured copper niobium composite wires are excellent candidates for the generation of intense pulsed magnetic fields (> 90T) as they combine both high electrical conductivity and high strength. Multi-scaled Cu-Nb wires can be fabricated by accumulative drawing and bundling (a severe plastic deformation technique), leading to a multiscale, architectured and nanostructured microstructure providing a unique set of properties. This work presents a comprehensive multiscale study to predict the anisotropic effective electrical conductivity based on material nanostructure and architecture. Two homogenization methods are applied: a mean-field theory and a full-field approach. The size effect associated with the microstructure refinement is taken into account in the definition of the conductivity of each component in the composites. The multiscale character of the material is then accounted for through an iterative process. Both methods show excellent agreement with each other. The results are further compared, for the first time, with experimental data obtained by the four-point probe technique, and also show excellent agreement. Finally, the qualitative and quantitative understanding provided by these models demonstrates that the microstructure of Cu-Nb wires has a significant effect on the electrical conductivity http://hdl.handle.net/10985/12174 Multiscale modeling of the elastic behavior of architectured and nanostructured Cu–Nb composite wires GU, TANG; CASTELNAU, Olivier; HERVE-LUANCO, E.; LECOUTURIER, F; PROUDHON, H; THILLY, L Nanostructured and architectured copper niobium composite wires are excellent candidates for the generation of intense pulsed magnetic fields (> 90T) as they combine both high strength and high electrical conductivity. Multi-scaled Cu–Nb wires are fabricated by accumulative drawing and bundling (a severe plastic deformation technique), leading to a multiscale, architectured, and nanostructured microstructure exhibiting a strong fiber crystallographic texture and elongated grain shapes along the wire axis. This paper presents a comprehensive study of the effective elastic behavior of this composite material by three multi-scale models accounting for different microstructural contents: two mean-field models and a full-field finite element model. As the specimens exhibit many characteristic scales, several scale transition steps are carried out iteratively from the grain scale to the macro-scale. The general agreement among the model responses allows suggesting the best strategy to estimate the effective behavior of Cu–Nb wires and save computational time. The importance of crystallographical and morphological textures in various cases is discussed. Finally, the models are validated by available experimental data with a good agreement. Sun, 01 Jan 2017 00:00:00 GMT http://hdl.handle.net/10985/12174 2017-01-01T00:00:00Z GU, TANG CASTELNAU, Olivier HERVE-LUANCO, E. LECOUTURIER, F PROUDHON, H THILLY, L Nanostructured and architectured copper niobium composite wires are excellent candidates for the generation of intense pulsed magnetic fields (> 90T) as they combine both high strength and high electrical conductivity. Multi-scaled Cu–Nb wires are fabricated by accumulative drawing and bundling (a severe plastic deformation technique), leading to a multiscale, architectured, and nanostructured microstructure exhibiting a strong fiber crystallographic texture and elongated grain shapes along the wire axis. This paper presents a comprehensive study of the effective elastic behavior of this composite material by three multi-scale models accounting for different microstructural contents: two mean-field models and a full-field finite element model. As the specimens exhibit many characteristic scales, several scale transition steps are carried out iteratively from the grain scale to the macro-scale. The general agreement among the model responses allows suggesting the best strategy to estimate the effective behavior of Cu–Nb wires and save computational time. The importance of crystallographical and morphological textures in various cases is discussed. Finally, the models are validated by available experimental data with a good agreement.