We implemented an incremental digital volume correlation (DVC) technique for large nonlinear deformation measurements, and apply the technique for cell deformations in a closed-cell polymethacrylimide (PMI). The DVC technique previously reported in literature has used the natural state as the reference image to calculate all stages of deformation. It does not converge when large nonlinear deformations are involved, as in the case of PMI foam in compression. In this paper, we implemented an incremental DVC technique by updating the reference volume image at the last former stage, in order to achieve the correlation. The incremental DVC technique is verified using simulated rotation test. An unconfined uniaxial compression experiment on a PMI foam was conducted and in-situ microtomography was acquired. The microstructural evolution of the PMI foam was captured during compression; the displacement fields are obtained using the incremental DVC method. The incremental DVC technique can be used to evaluate the microstructural evolution of materials under large nonlinear deformations on images obtained from different 3D imaging techniques, including those from x-ray, laser, ultrasound, magnetic resonance, and neutron sources.
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