Seminar Announcement, 05/05/2015
Levich Institute Seminar Announcement, 05/05/2015
Tuesday, 05/05/2015
2:00 PM
Steinman Hall, Room #312
(Chemical Engineering Conference Room)

Dr. Thibaut Divoux
CNRS Centre de Reserche Paul Pascal

"Yogurts Under Stress"

ABSTRACT


Biomaterials such as protein or polysaccharide gels are known to behave qualitatively as soft solids and to rupture under an external load. Combining optical and ultrasonic imaging to shear rheology we show that the failure scenario of a protein gel is reminiscent of brittle solids: after a primary creep regime characterized by a power-law behavior whose exponent is fully accounted for by linear viscoelasticity, fractures nucleate and grow logarithmically perpendicularly to shear, up to the sudden rupture of the gel. A single equation accounting for those two successive processes nicely captures the full rheological response. The failure time follows a decreasing power law with the applied shear stress, similar to the Basquin law of fatigue for solids. These results are in excellent agreement with recent fiber-bundle models that include damage accumulation on elastic fibers and exemplify protein gels as model, brittle-like soft solids.

BRIEF ACADEMIC/EMPLOYMENT HISTORY
  • 2002 - 2005 Undergraduate Studies @ENS, Paris (France)
  • 2005 - 2006 Agrégation de Physique, option Physique @ENS Cachan, Cachan (France)
  • 2006 - 2009 PhD @ENS Lyon on creep flows in granular materials, advisor J-C. Géminard
  • 2009 -2012 Postdoctoral fellow @Manneville's Lab - work on the yielding dynamics of Yield Stress Fluids
  • Since 2013: CNRS researcher - CRPP, Bordeaux - France.
  • Currently visiting researcher at G.H. McKinley's Lab in the framework of a collaboration subsidized by the France-MIT seed fund and the CNRS (PICS USA #06767)

RECENT RESEARCH INTERESTS

My research interests focus on the mechanical properties of soft glassy materials (SGM). Combining rheology and local techniques such as velocimetry, diffusion light scattering or particle tracking, I try to obtain simple pictures associated to the yielding/rupture of these materials. One of my goals is to provide a local scenario to the early response in creep experiments, in amorphous soft materials such as colloidal gels and model biopolymer gels. For the latter type of materials, deformation goes hand in hand with the release of solvent -also called syneresis- that I am currently trying to quantify thanks to original techniques such as interferometry and rheology under controlled normal force.



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