Low-resistive vibratory penetration in granular media

Area of Science:

• Physics
• Robotics
• Material Science

Background:

• Non-cohesive materials (sand, snow, cereals) present excavation challenges for animals and machines.
• Existing animal strategies (ants, clams, lizards) inspire but may not optimize technological solutions.
• Efficient digging in granular media remains a key challenge in robotics and engineering.

Purpose of the Study:

• To investigate the effect of mechanical vibrations on the resistance encountered when penetrating dry granular media.
• To explore novel methods for reducing digging forces beyond biomimicry.
• To assess the potential of vibrations for enhancing the performance of digging machines.

Main Methods:

• Experimentally applying small amplitude (approximately 10 μm) and low-frequency (50-200 Hz) mechanical vibrations to a dry granular medium.
• Measuring the resisting force during the penetration of an intruder into the vibrated granular material.
• Analyzing the granular bed's response to vibrations, focusing on fluidization and force chain rupture.

Main Results:

• Mechanical vibrations reduced the resisting force for intruder penetration by up to one order of magnitude.
• The observed reduction in resistance is attributed to local fluidization of the granular material.
• Vibrations induced the rupture of force chains within the granular medium, lowering bulk resistance.

Conclusions:

• Small amplitude, low-frequency mechanical vibrations are highly effective in reducing penetration resistance in dry granular media.
• This phenomenon, caused by local fluidization and force chain rupture, offers a promising avenue for technological advancement.
• The findings suggest a new strategy for improving the efficiency of digging robots and machinery.