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

Abstract

AbstractThis 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 µm. 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°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.