How to walk on water and survive bullet impacts? - PowerPoint PPT Presentation

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How to walk on water and survive bullet impacts?

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  1. How to walk on water and survive bullet impacts? Rheology of complex fluids and simulated polymer gels Explore SDSU 2012 Joris Billen PhD Candidate Computational Science San Diego State University & Claremont Graduate University Supervisor: Prof A. Baljon, Department of Physics (SDSU)

  2. What is a complex fluid? • Complex fluids are everywhere: • Kitchen (chocolate, mayonaise, milk, ketchup) • Human body (blood, mucus) • Products (Cosmetics, liquid crystals, Shaving cream) • Fluids showing non-linear viscous behaviours, as well as viscoelastic materials, are Complex Fluids. • But …what is non-linear viscous and viscoelastic behavior?

  3. Visco-elastic behavior After application of a stress… Permanent deformation: Viscous Restores initial configuration: Elastic Temporary restoration: Visco-elastic • Tendons, ligaments, polymers, toothpaste, gels,…

  4. Non-linear viscous behavior: Newtonian VS non-Newtonian? Slope= viscosity

  5. Non-linear viscous behavior: Newtonian VS non-Newtonian? shear thickening shear thinning

  6. How to walk on water? viscosity Shear thickening

  7. How to survive bullet impacts? viscosity Shear thickening

  8. Shear thinning viscosity

  9. Polymers Polymer = repeating units of monomers

  10. Associating polymer gels Polymer chains in a solvent Reversible Network

  11. Rheological response gel Shear thickening Shear thinning Newtonian Viscosity Shear rate [J.Sprakel et al., Soft Matter (2009)]

  12. Applications Contact lenses Wound dressings Paintball fill Cartilage replace-ment / implants Actin filaments Controlled drug delivery Injectable gels Self-healing materials

  13. So … what do you do all day?

  14. Modeling the physics of a polymer gel

  15. Computer simulations of polymer gels • 1000 polymer chains of 8 beads long • However …we don’t work with pictures but with files of • -coordinates of atoms • -connections in network

  16. Computer simulations of polymer gels • Calculate properties that are impossible to measure experimentally 6 3 2 3 5 4

  17. Our work on the cover of a magazine Structure gel network similar to robust computer networks J. Billen, M. Wilson, A. Rabinovitch, A. R. C. Baljon, Europhys. Lett. 87 (2009) 68003.

  18. Thank you for your attention!

  19. Non-Newtonian Dubstep