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Unified Granular Intrusion Dynamics for Planetary Materials

Unified Granular Intrusion Dynamics for Planetary Materials

This is a Preprint and has not been peer reviewed. This is version 1 of this Preprint.

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Authors

John Gregory Ruck, Shravan Pradeep, John C Bush, Eric D Sigg, Feifei Qian, Douglas J Jerolmack 

Abstract

Granular friction μ is a sensitive and poorly understood function of packing fraction ϕ. Every granular material has a distinct critical volume fraction ϕc that delineates two mechanical deformation modes – compaction for ϕ < ϕc, and dilation for ϕ > ϕc. Here we examine the relation(s) between friction and packing fraction, using quasi-static penetration tests in materials ranging from glass beads to highly heterogeneous lunar regolith simulant. Noncohesive materials collapse onto a master curve that relates changes in friction to the distance from ϕc, confirming that the handoff from compaction to dilation is a phase transition. The mechanical distinction between compaction and dilation regimes is highlighted with the addition of cohesive dust – relevant for lunar regolith – which has little effect for ϕ < ϕc, but drastically enhances strength for ϕ > ϕc. Our simple model improves predictions of granular resistance to intrusion, which can help to explore and manipulate soils on Earth and regolith on other planets. A reanalysis of Apollo era lunar penetration tests demonstrates the promise of our approach.

DOI

https://doi.org/10.31223/X5246P

Subjects

Physical Sciences and Mathematics

Keywords

granular friction, planetary material, phase transition, robotic intruder

Dates

Published: 2025-10-02 15:25

Last Updated: 2025-10-02 15:25

License

CC-BY Attribution-NonCommercial 4.0 International

Additional Metadata

Conflict of interest statement:
None