Spatiotemporal synchronized temperature and deformation fields measurement at elevated temperature using a single infrared camera and high-emissivity speckle pattern

The synchronous measurement of temperature and deformation fields using a single infrared camera reduce the complexity of temporal and spatial synchronization between different cameras, making it a versatile approach for thermodynamic studies of materials and structures at temperatures below 150 °C. However, as temperature increases, existing methods encounter challenges such as reduced measurement accuracy of temperature due to the varying emissivity of the sample surface, and decorrelation problem due to the degradation or detachment of the speckle pattern. To address these limitations, we propose an improved method that combines a single infrared camera with stable, high-emissivity, high-temperature-resistant speckles. This method involves pre-applying specialized carriers for temperature and deformation measurements on the sample surface using air plasma spraying (APS) with high-emissivity, high-temperature-resistant materials, such as zirconia ceramics powder. The adaptive threshold binarization and Laplacian interpolation algorithm were employed to extract desired full-field temperature data from the infrared images, while the displacement field was determined through digital image correlation (DIC). The displacement data were then used to retrieve corresponding temperatures at specific calculation points on the surface. The validity and accuracy of the proposed method were verified through experiments, including thermal expansion tests on stainless steel samples subjected to heating by a torch burner and on nickel-based alloy samples under uniform heating using quartz lamps. Owing to its simplicity and cost-effectiveness, the proposed method demonstrates significant potential as a robust and efficient technique for analyzing the thermo-mechanical properties of materials and structures under extreme high temperature environments.