Optical imaging of surface strain distribution up to 1500°C: Development of micro‐speckle pattern

Abstract Micro‐speckle patterns were fabricated using α‐Al2O3 and SiC micro‐particles for in‐plane strain distribution measurement at temperatures up to 1500°C using an ultraviolet high‐temperature observation system (UV‐HTOS) combined with a digital image correlation (DIC) technique. The experimental results showed that the measured mean surface strains of α‐Al2O3 were in good agreement with the calculated values obtained from thermal expansion coefficient and temperature difference. The proposed speckle pattern could be used for strain distribution measurement without degradation even after heating up to 1500°C. The results also demonstrated that the pattern fabricated in this study is effective to understand the heterogeneous deformation mechanism in composite materials applied in high‐temperature structural components.