High temperature digital image correlation evaluation of in-situ failure mechanism: An experimental framework with application to C/SiC composites

A high temperature digital image correlation (DIC) technique was developed, which was applied to study the in-situ fracture behavior of a carbon fibre reinforced silicon carbide matrix (C/SiC) composite. The displacement distribution and cracking information of the C/SiC single edge notched beam specimen can be monitored real-time, thanks to the improved DIC technique with special speckle patterns that can reach up to 1600°C. The results showed that the brittle to ductile transition temperature of C/SiC composites is about 1300°C. The new failure mechanisms of C/SiC composites at different experimental temperatures were further verified with the aid of X-ray diffraction and scanning electron microscope (SEM) techniques. In addition, the relationships between the fracture toughness, first-crack strength of C/SiC composites and environmental temperature were deduced. The proposed experimental method and testing results may shed some light on assessing the reliability and durability of C/SiC composites at high temperatures.