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Microstructure inducted stress concentrations in CVI‐CFC materials
Author(s) -
Piat Romana,
Schnack Eckart
Publication year - 2005
Publication title -
pamm
Language(s) - English
Resource type - Journals
ISSN - 1617-7061
DOI - 10.1002/pamm.200510155
Subject(s) - homogenization (climate) , microstructure , materials science , anisotropy , composite material , elasticity (physics) , nanoscopic scale , chemical vapor infiltration , nanotechnology , physics , optics , biodiversity , ecology , biology
Abstract Carbon/carbon materials produced by chemical vapour infiltration consist of carbon fibers embedded in an anisotropic matrix of pyrocarbon. In this study we propose: 1) an approach for hierarchical homogenization of material parameters; 2) an approach for prediction of the stress concentrations in this material. The model estimates material properties on two scales: nano and micro scale. The microstructural morphology of CFC‐material on the nano scale can be represented as distribution of mono crystals of pyrographite. For modeling the response at this scale we utilize the Eshelbi's theory for continuously distributed inclusions. The orientations distribution functions of inclusions (mono crystals) are used for calculation of the homogenized elasticity tensor of pyrographite. The numerical calculations of the stress fields in the samples characterized by different types of pyrocarbon coatings provides us the information about the (failure) regions with maximal (critical) values of stress. The obtained results demonstrate a good coincidence with experimentally identified failure regions. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)