Paper presented at ISTVS 2025 | 55th Conference of the International Society for Terrain-Vehicle Systems https://doi.org/10.56884/DZSIN0YU
Authors: Shunsuke Muryokoji, Shingo Ozaki
Keywords: Microgravity; Discrete Element Method (DEM); Van der Waals Force; Electrostatic Force; Hourglass
Abstract:
Understanding the behavior of granular materials under various low-gravity conditions is essential for planetary exploration, as it impacts lander interactions, rover mobility, and in-situ resource utilization processes. However, ground-based experiments using parabolic flights and drop tower facilities are limited by short-duration microgravity conditions, making it challenging to fully capture behavior of granular materials. To address this, numerical simulations provide a powerful alternative. This study employs the discrete element method (DEM) to simulate sand-outflow behavior from hoppers under reduced gravity, based on the Hourglass experiment conducted aboard the International Space Station (ISS). The experiment utilized artificial gravity (0.06G–2G) to observe the deposition and flow characteristics of different granular materials. Using the DEM, we modeled silica sand samples (#5 and #8), incorporating contact forces, rolling resistance, and van der Waals forces/electrostatic forces to evaluate their impact on particle motion. The results show that silica sand #5 exhibited minimal adhesion effects, whereas silica sand #8 demonstrated significant accumulation of sand on walls, particularly under lower gravity conditions. Moreover, neither van der Waals nor electrostatic forces alone could fully replicate experimental results, indicating that both must be considered for accurate modeling. These findings emphasize the importance of interparticle forces in regolith behavior under low gravity and provide insights into granular material interactions in extraterrestrial environments. This study could contribute to the design and optimization of robotic systems for planetary exploration, particularly in excavation, mobility, and construction applications.
Last updated
