High-temperature deformation measurement using optical imaging digital image correlation: Status, challenge and future

Deformation measurement is a fundamental and effective method for evaluating the high-temperature behavior of heat-resistant materials. As a widely non-contact deformation measurement technique, Digital Image Correlation (DIC) shows outstanding advantages in in-situ high-temperature observation and deformation measurements. However, at high temperatures, the main issues of thermal radiation, speckle pattern instability and heat haze cause image overexposure, decorrelation and strain accuracy reduction, respectively, leading to measurement failure. First, important advances in optical systems for high-temperature measurements using DIC are reviewed. High-temperature DIC is divided into white-illuminating optical system-based DIC (white-DIC), blue-illuminating optical system-based DIC (blue-DIC), and ultraviolet-illuminating optical system-based DIC (UV-DIC) for thermal radiation elimination. In particular, the principle and application of UV imaging for in-situ observation and measurement are emphasized. In addition, high-temperature speckle pattern fabrication and heat-haze mitigation are reviewed in detail. Finally, the status, challenges and future prospects of high-temperature optical imaging DIC are discussed.