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Controlling Wave Propagation through Nonlinear Engineered Granular Systems


Leonard, Andrea Beth (2013) Controlling Wave Propagation through Nonlinear Engineered Granular Systems. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/NF5J-5W42.

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We study the fundamental dynamic behavior of a special class of ordered granular systems in order to design new, structured materials with unique physical properties. The dynamic properties of granular systems are dictated by the nonlinear, Hertzian, potential in compression and zero tensile strength resulting from the discrete material structure. Engineering the underlying particle arrangement of granular systems allows for unique dynamic properties, not observed in natural, disordered granular media. While extensive studies on 1D granular crystals have suggested their usefulness for a variety of engineering applications, considerably less attention has been given to higher-dimensional systems. The extension of these studies in higher dimensions could enable the discovery of richer physical phenomena not possible in 1D, such as spatial redirection and anisotropic energy trapping. We present experiments, numerical simulation (based on a discrete particle model), and in some cases theoretical predictions for several engineered granular systems, studying the effects of particle arrangement on the highly nonlinear transient wave propagation to develop means for controlling the wave propagation pathways. The first component of this thesis studies the stress wave propagation resulting from a localized impulsive loading for three different 2D particle lattice structures: square, centered square, and hexagonal granular crystals. By varying the lattice structure, we observe a wide range of properties for the propagating stress waves: quasi-1D solitary wave propagation, fully 2D wave propagation with tunable wave front shapes, and 2D pulsed wave propagation. Additionally the effects of weak disorder, inevitably present in real granular systems, are investigated. The second half of this thesis studies the solitary wave propagation through 2D and 3D ordered networks of granular chains, reducing the effective density compared to granular crystals by selectively placing wave guiding chains to control the acoustic wave transmission. The rapid wave front amplitude decay exhibited by these granular networks makes them highly attractive for impact mitigation applications. The agreement between experiments, numerical simulations, and applicable theoretical predictions validates the wave guiding capabilities of these engineered granular crystals and networks and opens a wide range of possibilities for the realization of increasingly complex granular material design.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Granular; Hertz Contact; Nonlinear Stress Waves; Solitary Waves; Granular Crystals; Ordered Granular Networks; Impulsive Excitation;
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Applied Mechanics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Daraio, Chiara
Thesis Committee:
  • Lapusta, Nadia (chair)
  • Daraio, Chiara
  • Ravichandran, Guruswami
  • Kochmann, Dennis M.
Defense Date:23 April 2013
Funding AgencyGrant Number
Army Research Office MURIproject number W911NF0910436
Department of Energy Office of Science Graduate Fellowship Program (DOE SCGF)ORISE-ORAU under contract no. DE-AC05-06OR23100
Record Number:CaltechTHESIS:06122013-030022149
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for ch.3 adapted for ch.4 adapted for ch.4
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:7895
Deposited By: Andrea Leonard
Deposited On:04 Nov 2013 19:51
Last Modified:08 Nov 2023 00:21

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