Implementation of Nano-mechanics in Geotechnical Engineering
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Implementation of Nano-mechanics in Geotechnical Engineering. Hyungrae Cho And Chung R. Song. Department of Civil Engineering The University of Mississippi University, MS 38677. Olemiss Civil Engineering. Contents. Introduction Background Nano-mechanics Tentative Results Conclusions.

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Implementation of Nano-mechanics in Geotechnical Engineering

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Implementation of nano mechanics in geotechnical engineering

Implementation of Nano-mechanics in Geotechnical Engineering

Hyungrae Cho

And

Chung R. Song

Department of Civil Engineering

The University of Mississippi

University, MS 38677


Implementation of nano mechanics in geotechnical engineering

Olemiss Civil Engineering

Contents

  • Introduction

  • Background

  • Nano-mechanics

  • Tentative Results

  • Conclusions


Introduction

Olemiss Civil Engineering

Introduction

  • The macro-scale material behavior is a representation of the average micro-scale material behavior.

  • The micro-scale material behavior is a representation of the average molecular-scale (Nano- scale) material behavior.

  • By obtaining molecular-scale material properties, the macro-scale material behavior is obtained,

    • with limited input parameters and

    • with great accuracy and details.

  • With the blooming Nano-technology, molecular-scale material properties have more importance than ever.


Theoretical background traditional mm md nm

Olemiss Civil Engineering

Theoretical Background(Traditional MM, MD, NM)

Well developed.


Theoretical background traditional continuum mechanics

Olemiss Civil Engineering

Theoretical Background(Traditional Continuum Mechanics)

Where,

nK is the stiffness matrix, n is the coupling matrix,

n is the flow matrix, U is the incremental nodal displacement,

W is the incremental pore water pressure, t is the incremental time,

n is the equilibrium force, and n is the flow vector

Well developed.

Most things are smeared into the equilibrium equation.

-Elasticity, Plasticity, grain rotation, grain interaction, damage, …..


Theoretical background advantages disadvantages

Olemiss Civil Engineering

Theoretical Background(Advantages/Disadvantages)

Need to bridge Nano- Mechanics and Continuum Mechanics


Theoretical background bridging nano and continuum equivalent frame element method

Olemiss Civil Engineering

Theoretical Background Bridging Nano- and Continuum-(Equivalent frame element method)

Li and Chou (2003)

Odegard et al. (2001)

Ostoja-Starzewski, (2002)

Ansys

Molecular potential energy =Strain energy


Theoretical background bridging nano and continuum rve method

Olemiss Civil Engineering

Theoretical Background Bridging Nano- and Continuum-(RVE method)

A: Properties in molecular level

A’: Properties in continuum level

Voyiadjis et al. (2004)

DPD: Maiti et. al. (2004)


Theoretical background bridging nano and continuum for soils

Olemiss Civil Engineering

Continuum

Mechanics

(Macroscale)

Particulate

Mechanics

(Mesoscale)

Molecular Mechanics

(Nanoscale)

Theoretical Background Bridging Nano- and Continuum-for soils

  • Soil grains are continuum in Nano- to micro scale (sand grains and clay minerals).

  • But they are discrete media in macro scale (soil masss).

  • Therefore, bridging b/t Nano-, micro, and macro scales for soils shall be done as follows;


Tentative results surface charge of clay minerals

Olemiss Civil Engineering

Tentative Results(Surface charge of clay minerals)

Muscovite:

-194.165 kcal/mol

Kaolinite:

-162.832 kcal/mol

Montmorillonite:

-65604 kcal/mol


Tentative results properties of muscovite

Olemiss Civil Engineering

Tentative Results(Properties of muscovite)

Elastic Constants (GPa)

_______________________

397.3 341 453.2 -1.847e-010 15.78 8.953e-010

341 503.4 459.4 3.126e-010 -102.7 -8.669e-010

453.2 459.4 672 5.684e-011 -40.49 -2.558e-010

-9.419e-012 -1.377e-011 -1.421e-011 238.3 5.689e-012 -71.75

15.76 -102.7 -40.46 -2.078e-010 123.5 -7.194e-010

-7.529e-012 8.329e-012 -1.61e-011 -71.75 7.336e-012 229.5


Tentative results properties of quartz beta

Olemiss Civil Engineering

Tentative Results(Properties of Quartz-beta)

Elastic Constants (GPa)

_______________________

103.8 11.6 12.28 0.02317 -0.01545 -2.309

11.48 103.9 12.25 0.1154 -0.05009 2.353

12.13 12.23 95.51 0.2123 -0.07562 0.1028

0.01682 -0.03887 -0.02016 46.08 -2.373 0.01008

-0.08894 -0.0679 -0.04894 -2.455 40.21 0.09949

-2.259 2.331 0.02657 0.004098 0.1255 40.33


Tentative results bridging nano and micro using dem

Olemiss Civil Engineering

Tentative Results(Bridging nano- and micro using DEM)

Continuum?

Molecular Mechanics: E=104 GPa

μ=0.1061

Continuum Mechanics

FEM:

What can we do?

Particulate Mechanics

DEM: φ = 26.5o

for e=0.763


Conclusions remarks

Olemiss Civil Engineering

Conclusions/Remarks

  • With the aid of accessible software to Nano-mechanics, material scientists can predict the detailed material properties that was never possible in the past.

  • Application of Nano-mechanics to obtain the property of macro-scale requires substantial computational efforts, but it is impossible.

  • For soils bridging nano-, micro- and macro scales is achieved by combination of molecular mechanics, particular mechanics and continuum mechanics.


Thank you for your attention questions

Olemiss Civil Engineering

Thank you for your attention.Questions?


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