Microstructural fracture analysis of mono- and bicomponent agglomerates using in situ μCT and Digital Volume Correlation

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Understanding the fracture behavior of agglomerates is essential for predicting the performance of particulate materials in granulation, powder processing, and breakage-dominated applications. In particular, bicomponent agglomerates exhibit complex deformation and failure mechanisms that cannot be resolved by conventional mechanical testing alone. In this study, mono- and bicomponent agglomerates consisting of spherical soda–lime glass and polystyrene particles bonded with hydroxypropyl methylcellulose (HPMC) are investigated. Uniform specimens with controlled compositions ranging from single-component systems to mixed formulations were produced using an extrusion-based manufacturing process. The internal deformation behavior during compression is analyzed using in situ X-ray micro-computed tomography ( μ CT) combined with Digital Volume Correlation (DVC). A dedicated image-processing workflow, including intensity normalization, segmentation, density-based spatial clustering of applications with noise (DBSCAN), and particle labeling, enables particle-resolved displacement and strain measurements. Volumetric and deviatoric strain fields are subsequently evaluated using Local Indicators of Spatial Association (LISA) to quantify strain localization and damage evolution. The results reveal a transition from distributed deformation at low loads to localized strain concentrations preceding fracture. Significant composition-dependent differences in strain localization patterns are observed, demonstrating the influence of microstructural heterogeneity and interfacial interactions on fracture behavior. The presented workflow provides direct insight into particle-scale failure mechanisms and establishes a robust framework for investigating fracture processes in complex agglomerated materials.