1 / 15

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. Olemiss Civil Engineering. Contents. Introduction Background Nano-mechanics Tentative Results Conclusions.

tymon
Download Presentation

Implementation of Nano-mechanics in Geotechnical Engineering

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Implementation of Nano-mechanics in Geotechnical Engineering Hyungrae Cho And Chung R. Song Department of Civil Engineering The University of Mississippi University, MS 38677

  2. Olemiss Civil Engineering Contents • Introduction • Background • Nano-mechanics • Tentative Results • Conclusions

  3. 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.

  4. Olemiss Civil Engineering Theoretical Background(Traditional MM, MD, NM) Well developed.

  5. 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, …..

  6. Olemiss Civil Engineering Theoretical Background(Advantages/Disadvantages) Need to bridge Nano- Mechanics and Continuum Mechanics

  7. 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

  8. 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)

  9. 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;

  10. Olemiss Civil Engineering Tentative Results(Surface charge of clay minerals) Muscovite: -194.165 kcal/mol Kaolinite: -162.832 kcal/mol Montmorillonite: -65604 kcal/mol

  11. 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

  12. 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

  13. 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

  14. 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.

  15. Olemiss Civil Engineering Thank you for your attention.Questions?

More Related