Study on the calibration of discrete element interaction parameters for dry fine sand under dynamic impact

Investigating the mechanical properties and constitutive models of dry sand under dynamic impact has posed significant challenges in various fields, including blast protection, geotechnical engineering, and geophysics. This is due to the complex mechanical behavior exhibited by dry sand, which is a granular material consisting of grains of varying sizes with nearly zero cohesion. Obtaining reliable interaction parameters for particle behavior and comprehensive characterization of dynamic mechanical properties have proven to be especially demanding. In this study, stress–strain curves of dry fine sand were obtained through passively confined split Hopkinson pressure bar (SHPB) experiments at various strain rates. The discrete element interaction parameters were self-iteration calibrated using an optimization program that relied on the experimental data. Subsequently, the sand slug ejection experiment was proposed to validate the calibrated interaction parameters, where the SHPB apparatus was used as the loading platform, with a support sleeve and a piston attached to the tail end of the incident bar. Multiple lengths of dry sand slugs were inserted into the sleeve. The loading pulse was measured by the strain gauge mounted on the incident bar, and the velocities of the sand slug were monitored by a high-speed camera. The study demonstrated that the self-iteration calibrated interaction parameters are effective in precisely modeling the mechanical response of dry fine sand under dynamic impact. The proposed sand slug ejection experiment has the potential to validate the discrete element interaction parameters.