Elasticity and Wave Propagation in Granular Materials

Research output: ThesisPhD Thesis - Research UT, graduation UTAcademic

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Abstract

Particle simulations are able to model behavior of granular materials, but are very slow when large-scale phenomena and industrial applications of granular materials are considered. Even with the most advanced computational techniques, it is not possible to simulate realistic numbers of particles in large systems with complex geometries. Thus, continuum models are more desirable, where macroscopic field variables can be obtained from a micro-macro averaging procedure. However, aspects of microscopic scale are neglected in classical continuum theories (restructuring, geometric non linearity due to discreteness, explicit control over particle properties).

The focus of this work is the investigation of elastic and dissipative behavior of isotropic, dense assemblies. In particular, the attention is devoted on the effect of microscopic parameters (e.g. stiffness, friction, cohesion) on the macroscopic response (e.g. elastic moduli, attenuation). The research methodology combines experiments, numerical simulations, theory.

One goal is to extract the macroscopic material properties from the microscopic interactions among the individual constituent particles; for simple enough systems this can often be done using techniques from mechanics and statistical physics. While these simplified models can not capture all aspects of technically relevant realistic grains the fundamental physical phase transitions can be studied with these model systems.

Complex mixtures with more than one particle species can exhibit enhanced mechanical properties, better than each of the ingredients. The interplay of soft with stiff particles is one reason for this, but requires a more accurate formation of the interaction of deformable spheres. A new multi-contact approach is pro- posed which shows a better agreement between experiments and simulations in comparison to the conventional pair interactions.

The study of wave propagation in granular materials allows inferring many fundamental properties of particulate systems such as effective elastic and dissipative mechanisms as well as their dispersive interplay. Measurements of both phase velocities and attenuation provide complementary information about intrinsic material properties. Soft-stiff mixtures, with the same particle size, tested in the geomechanical laboratory, using a triaxial cell equipped with wave transducers, display a discontinuous dependence of wave speed with composition.

The diffusive characteristic of energy propagation (scattering) and its frequency dependence (attenuation) are past into a reduced order model, a master equation devised and utilized for analytically predicting the transfer of energy across a few different wavenumber ranges, in a one-dimensional chain.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • University of Twente
Supervisors/Advisors
  • Luding, Stefan , Supervisor
  • Magnanimo, Vanessa , Co-Supervisor
Award date26 Sep 2019
Place of PublicationEnschede
Publisher
Print ISBNs978-90-365-4860-1
DOIs
Publication statusPublished - 24 Sep 2019

Fingerprint

granular materials
wave propagation
elastic properties
propagation
attenuation
continuums
simulation
cohesion
interactions
phase velocity
ingredients
assemblies
particulates
stiffness
modulus of elasticity
transducers
friction
nonlinearity
mechanical properties
methodology

Keywords

  • Granular Materials
  • Wave propagation
  • Elasticity
  • Granular Mixture
  • Discrete element modeling
  • Particle simulation
  • Continuum Modeling

Cite this

@phdthesis{a28dbfefbce542778244bb139cf7aba9,
title = "Elasticity and Wave Propagation in Granular Materials",
abstract = "Particle simulations are able to model behavior of granular materials, but are very slow when large-scale phenomena and industrial applications of granular materials are considered. Even with the most advanced computational techniques, it is not possible to simulate realistic numbers of particles in large systems with complex geometries. Thus, continuum models are more desirable, where macroscopic field variables can be obtained from a micro-macro averaging procedure. However, aspects of microscopic scale are neglected in classical continuum theories (restructuring, geometric non linearity due to discreteness, explicit control over particle properties).The focus of this work is the investigation of elastic and dissipative behavior of isotropic, dense assemblies. In particular, the attention is devoted on the effect of microscopic parameters (e.g. stiffness, friction, cohesion) on the macroscopic response (e.g. elastic moduli, attenuation). The research methodology combines experiments, numerical simulations, theory.One goal is to extract the macroscopic material properties from the microscopic interactions among the individual constituent particles; for simple enough systems this can often be done using techniques from mechanics and statistical physics. While these simplified models can not capture all aspects of technically relevant realistic grains the fundamental physical phase transitions can be studied with these model systems.Complex mixtures with more than one particle species can exhibit enhanced mechanical properties, better than each of the ingredients. The interplay of soft with stiff particles is one reason for this, but requires a more accurate formation of the interaction of deformable spheres. A new multi-contact approach is pro- posed which shows a better agreement between experiments and simulations in comparison to the conventional pair interactions.The study of wave propagation in granular materials allows inferring many fundamental properties of particulate systems such as effective elastic and dissipative mechanisms as well as their dispersive interplay. Measurements of both phase velocities and attenuation provide complementary information about intrinsic material properties. Soft-stiff mixtures, with the same particle size, tested in the geomechanical laboratory, using a triaxial cell equipped with wave transducers, display a discontinuous dependence of wave speed with composition.The diffusive characteristic of energy propagation (scattering) and its frequency dependence (attenuation) are past into a reduced order model, a master equation devised and utilized for analytically predicting the transfer of energy across a few different wavenumber ranges, in a one-dimensional chain.",
keywords = "Granular Materials, Wave propagation, Elasticity, Granular Mixture, Discrete element modeling, Particle simulation, Continuum Modeling",
author = "{Taghizadeh Bajgirani}, Kianoosh",
year = "2019",
month = "9",
day = "24",
doi = "10.3990/1.9789036548601",
language = "English",
isbn = "978-90-365-4860-1",
publisher = "University of Twente",
address = "Netherlands",
school = "University of Twente",

}

Elasticity and Wave Propagation in Granular Materials. / Taghizadeh Bajgirani, Kianoosh .

Enschede : University of Twente, 2019. 214 p.

Research output: ThesisPhD Thesis - Research UT, graduation UTAcademic

TY - THES

T1 - Elasticity and Wave Propagation in Granular Materials

AU - Taghizadeh Bajgirani, Kianoosh

PY - 2019/9/24

Y1 - 2019/9/24

N2 - Particle simulations are able to model behavior of granular materials, but are very slow when large-scale phenomena and industrial applications of granular materials are considered. Even with the most advanced computational techniques, it is not possible to simulate realistic numbers of particles in large systems with complex geometries. Thus, continuum models are more desirable, where macroscopic field variables can be obtained from a micro-macro averaging procedure. However, aspects of microscopic scale are neglected in classical continuum theories (restructuring, geometric non linearity due to discreteness, explicit control over particle properties).The focus of this work is the investigation of elastic and dissipative behavior of isotropic, dense assemblies. In particular, the attention is devoted on the effect of microscopic parameters (e.g. stiffness, friction, cohesion) on the macroscopic response (e.g. elastic moduli, attenuation). The research methodology combines experiments, numerical simulations, theory.One goal is to extract the macroscopic material properties from the microscopic interactions among the individual constituent particles; for simple enough systems this can often be done using techniques from mechanics and statistical physics. While these simplified models can not capture all aspects of technically relevant realistic grains the fundamental physical phase transitions can be studied with these model systems.Complex mixtures with more than one particle species can exhibit enhanced mechanical properties, better than each of the ingredients. The interplay of soft with stiff particles is one reason for this, but requires a more accurate formation of the interaction of deformable spheres. A new multi-contact approach is pro- posed which shows a better agreement between experiments and simulations in comparison to the conventional pair interactions.The study of wave propagation in granular materials allows inferring many fundamental properties of particulate systems such as effective elastic and dissipative mechanisms as well as their dispersive interplay. Measurements of both phase velocities and attenuation provide complementary information about intrinsic material properties. Soft-stiff mixtures, with the same particle size, tested in the geomechanical laboratory, using a triaxial cell equipped with wave transducers, display a discontinuous dependence of wave speed with composition.The diffusive characteristic of energy propagation (scattering) and its frequency dependence (attenuation) are past into a reduced order model, a master equation devised and utilized for analytically predicting the transfer of energy across a few different wavenumber ranges, in a one-dimensional chain.

AB - Particle simulations are able to model behavior of granular materials, but are very slow when large-scale phenomena and industrial applications of granular materials are considered. Even with the most advanced computational techniques, it is not possible to simulate realistic numbers of particles in large systems with complex geometries. Thus, continuum models are more desirable, where macroscopic field variables can be obtained from a micro-macro averaging procedure. However, aspects of microscopic scale are neglected in classical continuum theories (restructuring, geometric non linearity due to discreteness, explicit control over particle properties).The focus of this work is the investigation of elastic and dissipative behavior of isotropic, dense assemblies. In particular, the attention is devoted on the effect of microscopic parameters (e.g. stiffness, friction, cohesion) on the macroscopic response (e.g. elastic moduli, attenuation). The research methodology combines experiments, numerical simulations, theory.One goal is to extract the macroscopic material properties from the microscopic interactions among the individual constituent particles; for simple enough systems this can often be done using techniques from mechanics and statistical physics. While these simplified models can not capture all aspects of technically relevant realistic grains the fundamental physical phase transitions can be studied with these model systems.Complex mixtures with more than one particle species can exhibit enhanced mechanical properties, better than each of the ingredients. The interplay of soft with stiff particles is one reason for this, but requires a more accurate formation of the interaction of deformable spheres. A new multi-contact approach is pro- posed which shows a better agreement between experiments and simulations in comparison to the conventional pair interactions.The study of wave propagation in granular materials allows inferring many fundamental properties of particulate systems such as effective elastic and dissipative mechanisms as well as their dispersive interplay. Measurements of both phase velocities and attenuation provide complementary information about intrinsic material properties. Soft-stiff mixtures, with the same particle size, tested in the geomechanical laboratory, using a triaxial cell equipped with wave transducers, display a discontinuous dependence of wave speed with composition.The diffusive characteristic of energy propagation (scattering) and its frequency dependence (attenuation) are past into a reduced order model, a master equation devised and utilized for analytically predicting the transfer of energy across a few different wavenumber ranges, in a one-dimensional chain.

KW - Granular Materials

KW - Wave propagation

KW - Elasticity

KW - Granular Mixture

KW - Discrete element modeling

KW - Particle simulation

KW - Continuum Modeling

U2 - 10.3990/1.9789036548601

DO - 10.3990/1.9789036548601

M3 - PhD Thesis - Research UT, graduation UT

SN - 978-90-365-4860-1

PB - University of Twente

CY - Enschede

ER -