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Shear stress fluctuations in the granular liquid and solid phases.
F Dalton1, F Farrelly, A Petri
1Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, sede di Tor Vergata, Via del Fosso del Cavaliere 100, 00133 Roma, Italy.
Physical Review Letters
|October 4, 2005
Summary
Shear stress fluctuations in granular materials are non-Gaussian in solid states due to force chains, but become Gaussian in fluid states. This transition predicts changes in the material's force-bearing mechanisms.
Area of Science:
- Physics
- Materials Science
- Rheology
Background:
- Granular materials exhibit complex behaviors under shear stress.
- Understanding stress distribution is crucial for predicting material failure and transitions.
Purpose of the Study:
- To investigate shear stress fluctuations in granular solids and fluids.
- To identify the relationship between stress distribution and force-bearing mechanisms during phase transitions.
- To explore the applicability of the fiber bundle model.
Main Methods:
- Experimental observation of shear stress fluctuations.
- Analysis of stress distribution and rigidity.
- Comparison with the fiber bundle model.
Main Results:
- Non-Gaussian stress distributions were observed in the solid-like phase, attributed to force chains.
- Peaks in rigidity and skewness indicated a transition to fluid behavior.
- Gaussian stress distributions were found in the fluid state, consistent with the central limit theorem.
- The fiber bundle model accurately reproduced stress distributions at the yield point.
Conclusions:
- The study elucidates the distinct stress fluctuation behaviors in granular solid and fluid states.
- A predictive link was established between low-shear-rate stress behavior and the transition to fluid dynamics.
- The fiber bundle model serves as a valuable tool for understanding stress propagation in granular systems.
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