Strain measurement at up to 3000 °C based on Ultraviolet-Digital Image Correlation

Abstract

Development in aerospace technology makes it increasingly important to understand the thermal-mechanical behavior of materials subject to high temperature ranging from 2000°C to 3000 °C. In this work, a simple and low-cost Ultraviolet-Digital Image Correlation (UV-DIC) system composed of a CCD camera, a telecentric lens and a single UV bandpass filter was proposed for deformation measurement at up to 3000 °C. Hafnium carbide (HfC) powder was used as the speckle pattern material. To verify the UV-DIC system and the speckle pattern, the coefficient of thermal expansion (CTE) of graphite heated by electric current was measured from 25 °C to 3000 °C. The results show that the system can effectively suppress strong heat radiation at up to 3000 °C, and that the prepared speckle pattern can withstand 3000 °C. Comparison of the measured CTE of graphite with that in the existing database verifies the feasibility and accuracy of the proposed method. The proposed method and technology lay the foundation for further development of the DIC in ultra-high temperature deformation measurement.