Damage and failure mechanisms of a 3-directional carbon/carbon composite under uniaxial tensile and shear loads

The mechanical behavior of a three-directional carbon/carbon (C/C) composit e under tensile and shear loads is investigated in relation with the failur e mechanisms and, the fiber architecture. This three-directional C/C compos ite was produced by Chemical Vapor Infiltration of a needled fiber preform of multiple layers of satin woven tows. The C/C composite exhibited several interesting features including an essentially non-linear stress-strain beh avior and permanent deformations. Three families of matrix cracks were iden tified under tensile and shear loads, including microcracks in the tows, in tertow delamination and cracks across the longitudinal tows. It was found t hat the delamination cracks affect preponderantly the stress-strain behavio r and the mechanical properties. Similar features in the mechanical behavio r and the failure mechanisms were highlighted under tension and under shear loading. (C) 1998 Acta Metallurgica Inc. Published by Elsevier Science Ltd . All rights reserved.