16. Correlation of Microscale Deformations to Macroscopic Mechanical Behavior Using Incremental Digital Volume Correlation of In-Situ Tomography

An incremental digital volume correlation (DVC) technique was developed to measure large nonlinear deformations on volumetric images acquired using X-ray micro-computed tomography (μ-CT). A series of bridging volumetric images are acquired during the loading of a specimen. The deformation in the neighboring images is sufficiently small to allow DVC calculation. The displacements are accumulated, and analyzed to determine their gradients for deformation measurements. The technique was applied for observation of internal deformations of Polymethacrylimide (PMI) foam, polymer bonded sugar (PBS), and granular materials in compression experiencing large nonlinear deformations. When PMI foam underwent compression, 17 states of the PMI were captured and large nonlinear deformations were observed. The PBS cylindrical specimen, in which sugar grains are embedded in hydroxylterminated polybutadiene (HTPB) binder matrix, was compressed up to 32 % of compressive strain without confinement. The debonding evolution was observed and discussed. On granular materials, a methodology was developed to determine for the force chains. These applications demonstrate that incremental DVC is a powerful technique for linking the microstructure with macroscopic mechanical behavior.