Low-velocity impact response and breakage characteristics of hollow brittle particles

Low-velocity impact responses of typical hollow brittle particles (HBPs) were tested with a strain-limited loading technique to investigate the particle breakage characteristics at both macro and particle levels. The quasi-static compressions were also conducted for comparison. Effects of strain rate and particle size distribution on the stress-strain response, particle breakage and macro deformation behaviors were discussed. Results show that the strength, plateau stress and energy dissipation of hollow brittle particles all exhibited significant strain rate sensitivity. The particle size gradations after single-impact compression were obtained through the laser diffraction technique. Quantitative analysis on the fragmentations and the Hardin relative breakage shown that the dynamic breakage ratio and the breakage extent of the hollow particles at the same strain were larger than that under quasi-static compressions. Moreover, it was found that the Hardin relative breakage generated by specific energy dissipation decreased with the strain rate. The reduction of fracture energy dissipation efficiency and the rate-dependent breakage response of particle breakage are the intrinsic reasons for bulk-scale strain rate effects of HBPs. Finally, the macro deformation behaviors of hollow brittle particles were analyzed through digital image correlation (DIC) technique. It was observed that there exists a competition mechanism between the boundary effect and the inertial effect in dominating the compression patterns. The deformation mechanism was sensitive to the loading velocity.