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Home page > Séminaires > Archives séminaires > Séminaires 2017 > Séminaire MSC. 12 juin 2017. Sébastien Manneville (Ens Lyon) :"How do yoghurts form, deform and break ?".

Séminaire MSC. 12 juin 2017. Sébastien Manneville (Ens Lyon) :"How do yoghurts form, deform and break ?"

Sauf mention contraire, les séminaires et les soutenances se déroulent à 11h30 en salle 454A du bâtiment Condorcet.


How do yoghurts form, deform and break ?

Prof. Sébastien Manneville, Laboratoire de physique de l’ENS Lyon

Abstract : Acid-induced protein gels (model yoghurts) display a multi-scale microstructure that is responsible for both their solid-like properties and their fragile behaviour when submitted to moderate deformation.

In this talk, I will first describe how gelation proceeds in these systems. Based on electron microscopy, confocal optical microscopy and rheological measurements, I will show that the underlying fractal microstructure leads to linear viscoelastic properties characterized by power laws that are well described by a constitutive framework using fractional derivatives.

I will then explore the response of model yoghurts to simple shear thanks to simultaneous rheology, imaging and velocimetry. Upon startup of shear, these viscoelastic materials show a generic nonlinear mechanical response characterized by pronounced stiffening prior to irreversible damage and failure, most often through macroscopic fractures. I will show that this response can be quantitatively described up to the onset of macroscopic failure in terms of a “damping function” built upon a nonlinear integral constitutive equation.

Finally, based on independent creep measurements, we use the Bailey’s durability criteria for brittle solids to predict the critical values of the stress and strain for failure, and how they scale with the applied shear rate. This provides a generalized failure criterion for biopolymer gels in a range of different deformation histories.

Work in collaboration with : Bavand Keshavarz, Thibaut Divoux, and Gareth H. McKinley


Contact : Équipe séminaires / Seminar team - Published on / Publié le 7 avril 2017


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