  This work presents a novel global digital image correlation (DIC) method,
based on a newly developed convolution finite element (C-FE) approximation. The
convolution approximation can rely on the mesh of linear finite elements and
enables arbitrarily high order approximations without adding more degrees of
freedom. Therefore, the C-FE based DIC can be more accurate than {the} usual FE
based DIC by providing highly smooth and accurate displacement and strain
results with the same element size. The detailed formulation and implementation
of the method have been discussed in this work. The controlling parameters in
the method include the polynomial order, patch size, and dilation. A general
choice of the parameters and their potential adaptivity have been discussed.
The proposed DIC method has been tested by several representative examples,
including the DIC challenge 2.0 benchmark problems, with comparison to the
usual FE based DIC. C-FE outperformed FE in all the DIC results for the tested
examples. This work demonstrates the potential of C-FE and opens a new avenue
to enable highly smooth, accurate, and robust DIC analysis for full-field
displacement and strain measurements.
