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The Role of Fabric in Frictional Properties of Phyllosilicate-Rich Tectonic Faults
Published on: November 6, 2021
Jammed frictional tetrahedra are hyperstatic
Max Neudecker1, Stephan Ulrich, Stephan Herminghaus
1Max Planck Institute for Dynamics and Self-Organization, 37077 Goettingen, Germany. max.neudecker@ds.mpg.de
Physical Review Letters
|July 30, 2013
Summary
We studied frictional tetrahedra packings and found that particle contact number increases with density, influenced by preparation methods. Edge-to-face contacts significantly contribute to this increase, with packings being mechanically overdetermined.
Area of Science:
- Physics
- Materials Science
- Statistical Mechanics
Background:
- Understanding granular materials and their mechanical properties is crucial.
- Tetrahedral shapes present unique packing challenges and behaviors.
- The influence of preparation methods on granular packing is not fully understood.
Purpose of the Study:
- To investigate the structural and mechanical properties of frictional tetrahedra packings.
- To determine how volume fraction and preparation protocols affect particle contacts.
- To analyze the hyperstatic nature of these packings.
Main Methods:
- Preparing frictional tetrahedra packings using three distinct experimental protocols.
- Varying volume fractions (ϕ) from 0.469 to 0.622 under isobaric conditions.
- Analyzing packing structures using x-ray microtomography.
Main Results:
- Contact number (Z) increases with volume fraction (ϕ) but is dependent on the preparation protocol.
- Edge-to-face contacts constitute approximately 50% of the increase in Z.
- The number of constraints per particle (C) rises with ϕ, indicating hyperstaticity.
Conclusions:
- Granular packing structure, specifically contact number, is sensitive to both density and preparation history.
- Edge-to-face contacts play a critical role in the mechanical stability of tetrahedra packings.
- Even low-density tetrahedra packings are mechanically overdetermined (hyperstatic).
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