Experiments and modelling of the compressive behaviour of two SiC ceramics

To analyse compressive damage generated during a high-energy impact on ceramic targets, quasi-static uniaxial compressive tests are performed on two silicon carbide grades. These two grades (S-SiC and SiC-B) are characterised by different processing routes, porosity levels and tensile strengths. A new specimen geometry is proposed. Post-mortem studies carried out on a specimen embedded before compression allow us to visualise the final damage pattern. A highspeed camera is also used. Photographs of cracking and debris ejection are obtained a few microseconds after the inception of failure. In addition, thin strips are cut out of S-SiC and SiC-B specimens loaded and unloaded before failure. An anisotropic damage model is introduced to explain the failure scenario. A first numerical simulation substantiates the hypothesis of failure caused by tensile stresses induced by a roughness defect. A second analysis using the mesh of a half specimen matches the different observations obtained from post-mortem studies and with the high-speed camera. (C) 2002 Elsevier Ltd. All rights reserved.