Interlaminar fracture of carbon fibre reinforced SiC under mode I and II loading: Determination of parameters and FE-modelling

Abstract: The interlaminar energy release rates of carbon fibre reinforced SiC, were determined experimentally under mode I and II loading. The investigated CMC-material was produced from carbon fabrics by liquid silicon infiltration process. The interlaminar crack propagation was investigated on artificially pre-cracked samples. The cracks were orientated parallel to the 0/90°-fibre reinforcement. The standardized test geometries from CFRPs for Double Cantilever Beam- and End-Notched Flexure test were adapted to account for the CMC-specific material properties (low bending strength relative to the interlaminar fracture toughness). The experimental load deflection curves were evaluated in comparison with analytical results from LEFM and the results from Cohesive Zone FE-Modelling. A good correlation between experimental, analytical and numerical results was gained for the crack initiation in both crack opening modes. The deviation of the experimental crack propagation behaviour from the analytical and numerical results could be explained by the increase of fracture toughness during crack propagation