Drag force scaling for penetration into granular media
Hiroaki Katsuragi1, Douglas J Durian
1Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Summary
Projectile impact dynamics in granular media were studied. Inertial drag scales with internal friction, while frictional drag depends on the square-root of densities, explaining penetration depth.
Area of Science:
- Physics
- Granular Mechanics
- Material Science
Background:
- Understanding projectile penetration into granular materials is crucial for various applications.
- Previous models struggled to explain observed penetration depth scaling due to complex drag forces.
Purpose of the Study:
- To analyze the impact dynamics of projectiles in non-cohesive granular media.
- To elucidate the scaling laws for inertial and frictional drag forces.
- To provide a unified explanation for projectile penetration depth.
Main Methods:
- Experimental measurement of impact dynamics for spherical and cylindrical projectiles.
- Analysis of drag forces (inertial and frictional) based on projectile and granular media properties.
- Material-dependent scaling analysis.
Main Results:
- Inertial drag force exhibits fluid-like scaling, modulated by the internal friction coefficient.
- Frictional drag force scales with the square-root of both projectile and granular medium densities.
- The observed scaling cannot be explained by simple granular hydrostatic pressure and Coulomb friction models.
Conclusions:
- The study reveals distinct scaling behaviors for inertial and frictional drag forces during projectile impact.
- A new understanding of granular drag forces is established, explaining previously unexplained penetration phenomena.
- The findings offer a more accurate predictive framework for projectile penetration in granular materials.
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