Particle shape effect on dynamic mechanical responses, energy conversion and fragmentation behaviours of granular materials under impact

Abstract

This study evaluates the influence of particle shape on dynamic mechanical behaviours, energy conversion processes, particle breakage mechanisms, and particle morphology evolution of granular materials under impact loading. Dynamic compression experiments at high strain rate (750 s⁻¹ - 950 s⁻¹) are performed on glass particles with different initial particle shapes via the split Hopkinson bar device. Different compressive strain levels are achieved by utilizing striker bars of varying lengths. The particle size and morphological parameters are quantitatively characterized through high-resolution micro-computed tomography (micro-CT) imaging with a spatial resolution of 6 μm. More regular-shaped particles exhibit stronger resistance under impact compared to their irregular-shaped counterparts, resulting in a smaller breakage extent. Additionally, regular-shaped particles dissipate more external input energy by converting more into internal energy instead of kinetic energy. The scanning electron microscope results reveal that particle melting occurs during dynamic particle fragmentation. The co-evolving laws of particle size and shape under different impact stress levels demonstrate that regular-shaped particles are susceptible to abrasion damage, while irregular-shaped particles are prone to shattering. Particle crushing-induced shape alteration is highly dependent on the initial particle shape. Parameter correlation analysis indicates that the elongation parameter is consistently highly positively related to the particle breakage parameter, the Hardin breakage index, regardless of the initial particle shape.