Breakage probability of granules during repeated loading

•Granular behaviour differs when loaded at different contacts.•The contact stiffness increases with increasing number of localized loads.•The contact area increases with increasing number of localized loads.•Preloading of granules advances its breakage probability.•The lower the preloading intensity, the lesser is the increase in breakage probability.

In order to investigate the breakage behaviour of inhomogeneous particulate products such as fine agglomerates i.e. granules, their structural inhomogeneity has to be taken into consideration. In this article, considering the contact at each load during repeated loading, we describe from a micro-mechanical perspective, the differences in the contact area, contact stiffness and fatigue, and from an energetic perspective, the differences in the breakage probability. As model test materials, Geldart D elasto-plastic γ-Al2O3 granules had been selected and tested by quasi-static compression, low-velocity dynamic pendulum double-impact and high-velocity dynamic impact using a pneumatic cannon. Furthermore, we also describe the influence of preloading by double-impact on the breakage probability of granules subsequently loaded by dynamic impact.

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