Backward Incremental Digital Volume Correlation for High-Fidelity Internal Deformation Mapping in IDOX/Estane Particulate Composites

Abstract

In-situ X-ray micro-computed tomography (µCT) combined with Digital Volume Correlation (DVC) has become a cornerstone for quantifying internal deformation and damage in particulate composite materials. However, conventional DVC often struggles to maintain accuracy when materials undergo large nonlinear deformations accompanied by severe cracking and structural discontinuity. This paper addresses these limitations by implementing a robust backward incremental DVC approach to analyze the failure mechanisms of a mock plastic-bonded explosive (PBX) composite. The experimental setup involved a cylindrical specimen composed of IDOX crystals (75–150 μm) embedded in a polyurethane-based Estane binder. During unconfined compression, sequential µCT scans were acquired to capture the internal structural evolution. Unlike conventional forward-marching methods, the backward approach performs correlations in reverse, processing from the most deformed and fragmented state back to the original undeformed configuration through incremental steps. This methodology significantly enhances displacement tracking fidelity, particularly in regions where severe cracking and interfacial failure typically cause a loss of correlation in traditional frameworks. The results demonstrate that backward incremental DVC provides superior resolution of displacement and deformation fields near crack-affected regions. This high-fidelity mapping allows for the detailed observation of critical failure stages, including grain-binder interface delamination and subsequent crack coalescence. By successfully capturing these complex, grain-scale interactions, the study provides a vital dataset for the validation of high-fidelity numerical simulations. Ultimately, this approach offers a more reliable pathway for characterizing the intricate mechanical response and fracture evolution of heterogeneous particulate composites under extreme loading conditions.