Rapid assessment of the dependence of flexural elastic modulus on temperature through in-situ image analysis

This study aimed to develop a method for rapid and precise measurement of the elastic modulus at high temperatures. High-temperature in-situ microscopy was used in conjunction with a testing apparatus to measure the deformation of a specimen in three-point bending test. The bending deflection was determined in situ by measuring the relative change between the test point on the specimen and a fixed reference point. The deflection was correlated with the elastic modulus to obtain the dependence of the elastic modulus on temperature. The ratio between high- and room-temperature deflection of the bending beam was measured using the relative method and image analysis, with an identical scene and focal length for each photograph and a resolution of less than 1 mu m. The deflection ratio was then converted into the ratio between high- and room-temperature elastic modulus, enabling the high-temperature modulus to be quickly derived. The experiments were performed on a sample made of silicon carbide fiber braided layered composite. The results showed that the elastic modulus changed little within 1100 degrees C, remaining between 80 and 84 GPa. Contrarily, constant-load tests indicated that the creep of this material was noticeable, making it difficult to obtain reliable elastic modulus.