High accuracy measurement of heterogeneous deformation field using spatial-temporal subset digital image correlation

Subset-based digital image correlation (DIC) has limitations in subset size selection for heterogeneous deformation field measurement. To maintain good spatial resolution, selecting sufficiently small subsets is necessary, but the measurement resolution is reduced because of poor matching information, inducing large errors in the correlation matching procedure. Spatial-temporal subset digital image correlation (STS-DIC) incorporates the temporal continuity of displacement in the deformation analysis. This can increase the matching information of subset in the temporal dimension. Here, the advantages of STS-DIC for the measurement of heterogeneous deformation fields were investigated through simulations and experiments. The results demonstrated that the measurement resolution was improved while ensuring a good spatial resolution for heterogeneous deformation field measurement by using STS-DIC. Finally, STS-DIC was applied to calculate the displacement field near a precast crack, and the stress intensity factors were calculated accurately from high accuracy displacement fields.