Force networks and elasticity in granular silos
J F Wambaugh1, R R Hartley, R P Behringer
1Department of Physics, Duke University, Durham, NC 27708, USA. wambaugh.john@epa.gov
The European Physical Journal. E, Soft Matter
|June 29, 2010
Summary
Researchers studied force networks in granular silos, finding that pressure saturation depends on depth and material preparation. Particle elasticity influences force propagation, leading to nonlinear responses under overload.
Area of Science:
- Physics
- Materials Science
- Engineering
Background:
- Classical Janssen models predict pressure saturation in granular silos due to force redirection to walls.
- Previous experiments lacked detailed internal force network data.
Purpose of the Study:
- To experimentally investigate force networks in a 2D granular silo.
- To compare experimental results with Janssen-like model predictions.
- To understand the nonlinear pressure response to overloads.
Main Methods:
- Utilized photoelastic particles to visualize internal force networks in a 2D granular silo.
- Averaged ensembles of experimental force networks to determine mean behavior.
- Applied controlled overloads to the silo material.
Main Results:
- Observed that the force redirection parameter varies with depth, deviating from Janssen models.
- Found that material preparation affects pressure saturation (either saturating or continuously building).
- Documented a nonlinear response to overloads, including the 'giant overshoot' effect and deep pressure propagation for smaller loads.
Conclusions:
- Meso-scale force network phenomena explain nonlinear pressure profiles in granular silos.
- Particle elasticity plays a crucial role in stabilizing force networks and enabling deep pressure propagation under specific load conditions.
- Janssen-like behavior emerges only under larger overload conditions where the force network rearranges.
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