In-situ evaluation of C/SiC composites via an ultraviolet imaging system and microstructure based digital image correlation

Carbon fibre reinforced silicon carbide (C/SiC) composites were in situ observed up to 1400°C using an ultraviolet (UV) imaging system. The captured images were analysed by mean grey values at different temperatures. Thermal strain fields were obtained via digital image correlation (DIC) using the microstructure as speckle patterns (microstructure based DIC, M-DIC). The results show that it was effective using UV imaging system for in situ observation of surface of C/SiC composite up to 1400°C. Below 1000°C, the C/SiC kept no change while above 1000°C the change of SiC occurred. Local strain showed heterogeneous values based on the microstructure of C/SiC. The averaged coefficient of thermal expansion of cabon fibre bundles in composite measured agreed well with the literature data.