https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Thu, 14 May 2026 10:31:55 GMT 2026-05-14T10:31:55Z http://hdl.handle.net/10985/9747 Assessment of geometrical and transport properties of a fibrous C/C composite preform as digitized by X-ray CMT. Part II: heat and gas transport properties VIGNOLES, Gérard; COINDREAU, Olivia; AHMADI-SENICHAULT, Azita; BERNARD, Dominique Raw and partially infiltrated carbon–carbon composite preforms have been scanned by high-resolution synchrotron radiation x-ray computerized microtomography. Three-dimensional high-quality images of the pore space have been produced at two distinct resolutions and have been used for the computation of transport properties: heat conductivity, binary gas diffusivities, Knudsen diffusivities, and viscous flow permeabilities. The computation procedures are based on a double change-of-scale strategy suited to the bimodal nature of pore space and on the local determination of transport anisotropy. Good agreement has been found between all calculated quantities and experimental data. I. Mon, 01 Jan 2007 00:00:00 GMT http://hdl.handle.net/10985/9747 2007-01-01T00:00:00Z VIGNOLES, Gérard COINDREAU, Olivia AHMADI-SENICHAULT, Azita BERNARD, Dominique Raw and partially infiltrated carbon–carbon composite preforms have been scanned by high-resolution synchrotron radiation x-ray computerized microtomography. Three-dimensional high-quality images of the pore space have been produced at two distinct resolutions and have been used for the computation of transport properties: heat conductivity, binary gas diffusivities, Knudsen diffusivities, and viscous flow permeabilities. The computation procedures are based on a double change-of-scale strategy suited to the bimodal nature of pore space and on the local determination of transport anisotropy. Good agreement has been found between all calculated quantities and experimental data. I. http://hdl.handle.net/10985/9984 Effective heat conductivities of partly infiltrated fibrous media AHMADI-SENICHAULT, Azita; VIGNOLES, Gérard; COINDREAU, Olivia; ROS, William; GOULARD DIAS, Fagner The present work has been motivated by the context of feeding a global model of thermal-gradient chemical vapour infiltration process for the fabrication of fibre-reinforced ceramic matrix composites: the heat conductivity has to be known in the material as a function of the pore volume distribution, at different stages of infiltration. Since the composite preform is made of woven fibres, the medium is highly anisotropic: the heat conductivity has a tensorial character which has to be retrieved. We propose an approach based on a double up-scaling. First, the fibre-scale effective longitudinal and transverse conductivities are computed for several volume fractions of matrix and fibres, using a periodic unit cell as a computational domain. The second change of scale takes precisely into account the actual architecture of the composite thanks to 3D X-ray tomographic imaging. The 3D blocks are processed in order to retrieve the local orientation of the fibres in various sub-domains; the local heat conductivities are then affected to the sub-domains, and a volume averaging procedure is applied for the determination of the global effective conductivity. Several application examples are presented and discussed. Thu, 01 Jan 2009 00:00:00 GMT http://hdl.handle.net/10985/9984 2009-01-01T00:00:00Z AHMADI-SENICHAULT, Azita VIGNOLES, Gérard COINDREAU, Olivia ROS, William GOULARD DIAS, Fagner The present work has been motivated by the context of feeding a global model of thermal-gradient chemical vapour infiltration process for the fabrication of fibre-reinforced ceramic matrix composites: the heat conductivity has to be known in the material as a function of the pore volume distribution, at different stages of infiltration. Since the composite preform is made of woven fibres, the medium is highly anisotropic: the heat conductivity has a tensorial character which has to be retrieved. We propose an approach based on a double up-scaling. First, the fibre-scale effective longitudinal and transverse conductivities are computed for several volume fractions of matrix and fibres, using a periodic unit cell as a computational domain. The second change of scale takes precisely into account the actual architecture of the composite thanks to 3D X-ray tomographic imaging. The 3D blocks are processed in order to retrieve the local orientation of the fibres in various sub-domains; the local heat conductivities are then affected to the sub-domains, and a volume averaging procedure is applied for the determination of the global effective conductivity. Several application examples are presented and discussed.