Fig. 1. Schematic diagram of the DIC method. (a) Reference image; (b) target image

Fig. 2. Physical image of the specimen. (a) Original image without speckle; (b) speckle pattern

Fig. 3. Principle of thermal deformation image acquisition and measurement system

Fig. 4. Outer diameters of the specimen for the reference image and the target image. (a) Reference image (180 ℃); (b) target image (20 ℃)

Fig. 5. Change curve of the outer diameter of the specimen during the cooling process

Fig. 6. Finite element meshing diagram of the specimen

Fig. 7. Simulation result of thermal deformation of the specimen