Fig. 1. Schematic of DIC method

Fig. 2. Simulated speckle images. (a) Reference image;(b) shear band image with strain gradient

Fig. 3. Evolutions of E₁ and fitting coefficient with N

Fig. 4. Distributions of average γ_xy. (a) Measuring point interval is 4 pixel; (b) measuring point interval is 2 pixel; (c) measuring point interval is 1 pixel

Fig. 5. Errors of average γ_xy. (a) Measuring point interval is 4 pixel; (b) measuring point interval is 2 pixel; (c) measuring point interval is 1 pixel

Fig. 6. Similar material model

Fig. 7. γ_max of least square fitting for different Δx. (a) Δx=140; (b) Δx=300; (c) Δx=400

Fig. 8. γ_max of least absolute deviation fitting for different Δx. (a) Δx=140; (b) Δx=300; (c) Δx=400

Fig. 9. Distributions of γ_max in monitoring line for different Δx. (a) Δx=140; (b) Δx=300; (c) Δx=400