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Force Chains, Friction, and Flow: Behavior of Granular Media across Length Scales


Hurley, Ryan Colt (2016) Force Chains, Friction, and Flow: Behavior of Granular Media across Length Scales. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z91Z429J.


We study the behavior of granular materials at three length scales. At the smallest length scale, the grain-scale, we study inter-particle forces and "force chains". Inter-particle forces are the natural building blocks of constitutive laws for granular materials. Force chains are a key signature of the heterogeneity of granular systems. Despite their fundamental importance for calibrating grain-scale numerical models and elucidating constitutive laws, inter-particle forces have not been fully quantified in natural granular materials. We present a numerical force inference technique for determining inter-particle forces from experimental data and apply the technique to two-dimensional and three-dimensional systems under quasi-static and dynamic load. These experiments validate the technique and provide insight into the quasi-static and dynamic behavior of granular materials.

At a larger length scale, the mesoscale, we study the emergent frictional behavior of a collection of grains. Properties of granular materials at this intermediate scale are crucial inputs for macro-scale continuum models. We derive friction laws for granular materials at the mesoscale by applying averaging techniques to grain-scale quantities. These laws portray the nature of steady-state frictional strength as a competition between steady-state dilation and grain-scale dissipation rates. The laws also directly link the rate of dilation to the non-steady-state frictional strength.

At the macro-scale, we investigate continuum modeling techniques capable of simulating the distinct solid-like, liquid-like, and gas-like behaviors exhibited by granular materials in a single computational domain. We propose a Smoothed Particle Hydrodynamics (SPH) approach for granular materials with a viscoplastic constitutive law. The constitutive law uses a rate-dependent and dilation-dependent friction law. We provide a theoretical basis for a dilation-dependent friction law using similar analysis to that performed at the mesoscale. We provide several qualitative and quantitative validations of the technique and discuss ongoing work aiming to couple the granular flow with gas and fluid flows.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Granular materials, force chains, friction, granular flows, smoothed particle hydrodynamics, constitutive laws
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Applied Mechanics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Andrade, Jose E.
Thesis Committee:
  • Ravichandran, Guruswami (chair)
  • Bhattacharya, Kaushik
  • Lamb, Michael P.
  • Andrade, Jose E.
Defense Date:8 September 2015
Non-Caltech Author Email:rchurley (AT)
Funding AgencyGrant Number
Air Force Office of Scientific ResearchFA9550-12-1-0091
Defense Threat Reduction AgencyHDTRA1-12-1-0041
Projects:JPL ("Technologies for Increased Landing Accuracy, Payload Mass Fraction, and Landing Site Elevation"), Keck Institute for Space Studies ("xTerramechanics: Characterization and Modeling of Spacecraft-Regolith Interactions")
Record Number:CaltechTHESIS:09212015-105224808
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for ch. 2 adapted for ch. 3 adapted for ch. 4
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9162
Deposited By: Ryan Hurley
Deposited On:08 Oct 2015 16:45
Last Modified:04 Oct 2019 00:10

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