5:15 PM - 7:15 PM
[SCG62-P10] Effects of Intruder’s Shape and Interface Friction on Penetration Resistive Force into Dry and Cohesive Granular Layers
Keywords:cohesive granular material, discrete element method, penetration resistive force
On solid planetary surfaces covered with granular materials such as sand or regolith, there are various activities including rover locomotion, spacecraft landings, and soil excavation. These fundamental processes involve intruders "pushing" into or "penetrating" the granular layer. Thus, understanding penetration resistive forces in granular layers is crucial for accurately predicting the behavior of mechanical systems. Previous studies have proposed models that predict penetration resistive forces using the angle of repose [1]. However, these models have limitations, such as being inapplicable to cohesive granular materials like wet soil and insufficiently considering the influence of the tip angle of intruders due to their focus on simplified intruder shapes. To address these issues, our previous research investigated the effect of tip angles on penetration resistive forces [2] and proposed an extension of the model to accommodate cohesive granular materials [3]. However, the influence of intruder cross-sectional geometry and interface friction characteristics had not been examined. Therefore, we investigated these effects.
In this study, we conducted numerical simulations using the discrete element method (DEM), where an intruder penetrated a granular layer composed of numerous particles with an average diameter of 2 mm. We varied the intruder shape (cone, square pyramid, triangular prism) and the friction coefficient between the intruder and particles (0.0, 0.1, 0.3, 0.5, 0.7). Additionally, as in [3], we changed the angle of repose, tip angle of the intruder, and interparticle cohesive stress. The penetration resistive forces obtained from the simulations were compared with the predicted values from the previously proposed model in [3]. The results showed that while the existing model can explain the influence of intruder shape, it cannot account for a wide range of angles of repose, interparticle cohesive stresses, and intruder-particle friction coefficients. To reveal the discrepancy, we investigated failure modes within the granular layer during penetration. As a result, the analysis showed that the failure mode varies depending on the angle of repose". Therefore, we modified the model parameters related to the angle of repose based on the failure mode. Additionally, we introduce an empirical model equation from geotechnical engineering [4] to account for the effect of the intruder-particle friction coefficients. These modifications enable the proposed model to predict penetration resistive forces across various granular and intruder properties.
[1] W. Kang et al., Nat. Commun. 9: 1101 (2018).
[2] N. Iikawa and H. Katsuragi, Proceedings of the 21st International and 12th Asia-Pacific Regional Conference of the ISTVS, 4927 (2024). https://doi.org/10.56884/N04X6LSL
[3] N. Iikawa and H. Katsuragi, Acta Geotech. 1-17 (2024). https://doi.org/10.1007/s11440-024-02456-z
[4] B. Xi et al, Granul. Matter 25(4), 1–15 (2023).
In this study, we conducted numerical simulations using the discrete element method (DEM), where an intruder penetrated a granular layer composed of numerous particles with an average diameter of 2 mm. We varied the intruder shape (cone, square pyramid, triangular prism) and the friction coefficient between the intruder and particles (0.0, 0.1, 0.3, 0.5, 0.7). Additionally, as in [3], we changed the angle of repose, tip angle of the intruder, and interparticle cohesive stress. The penetration resistive forces obtained from the simulations were compared with the predicted values from the previously proposed model in [3]. The results showed that while the existing model can explain the influence of intruder shape, it cannot account for a wide range of angles of repose, interparticle cohesive stresses, and intruder-particle friction coefficients. To reveal the discrepancy, we investigated failure modes within the granular layer during penetration. As a result, the analysis showed that the failure mode varies depending on the angle of repose". Therefore, we modified the model parameters related to the angle of repose based on the failure mode. Additionally, we introduce an empirical model equation from geotechnical engineering [4] to account for the effect of the intruder-particle friction coefficients. These modifications enable the proposed model to predict penetration resistive forces across various granular and intruder properties.
[1] W. Kang et al., Nat. Commun. 9: 1101 (2018).
[2] N. Iikawa and H. Katsuragi, Proceedings of the 21st International and 12th Asia-Pacific Regional Conference of the ISTVS, 4927 (2024). https://doi.org/10.56884/N04X6LSL
[3] N. Iikawa and H. Katsuragi, Acta Geotech. 1-17 (2024). https://doi.org/10.1007/s11440-024-02456-z
[4] B. Xi et al, Granul. Matter 25(4), 1–15 (2023).