Effective heat conductivities of partly infiltrated fibrous media
TypeCommunications sans actes
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.
Showing items related by title, author, creator and subject.
Thermographic and tomographic methods for tridimensional characterization of thermal transfer in silica/phenolic composites BESSON, Gerard; AHMADI-SENICHAULT, Azita; CATY, Olivier; AYVAZYAN, Vahan; GREGORI, Maria Luisa; COSTA, S.F.; VIGNOLES, Gérard (Composites Part B: Engineering, 2016)Silica/phenolic composite materials are often used in thermal protection systems (TPS) for atmospheric re-entry. The present work aims to compare two different approaches to assess heat transfer properties of these materials: ...
VIGNOLES, Gérard; BRESSON, Grégory; LORRETTE, Christophe; AHMADI-SENICHAULT, Azita (Journal of Physics Conference Series, 2012)We propose a lightweight method for the determination of heat diffusivity of silica fiber bundles based on the use of a laser and an IR camera. The fiber bundle is maintained in traction in a holder; exposition is made as ...
BRESSON, Grégory; CATY, Olivier; MERZEAU, Jonathan; DAU, Frédéric; AHMADI-SENICHAULT, Azita; VIGNOLES, Gérard (Association Française de Mécanique, 2013)Silica/phenolic composites are used in atmospheric re-entry heat shield parts in spatial and strategic domains. For this application, the material is submitted to thermo-mechanical stresses that lead to delaminations. To ...
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 (Material Research Society, 2007)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 ...
Thermographic and tomographic methods for three-dimensional characterization of thermal diffusion in silica/phenolic composites AHMADI-SENICHAULT, Azita; VIGNOLES, Gérard; BRESSON, Grégory; CATY, Olivier; AYVAZYAN, Viguen; GREGORI, Maria Luisa; COSTA, S.F. (2014)Aeronautical and space vehicles include many parts made of composite materials. The thermal design of these materials is critical versus their application. Indeed, the presence of very high thermal gradients during use may ...