Programme pour le thème S04 mercredi après midi salle E

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15H40 : n° 754 Coupling of boundary integral and finite element methods to model the deformation of a microcapsule in flow

Johann Walter Anne-Virginie Salsac Dominique Barthès-Biesel
CNRS UMR6600 - Université de Technologie de Compiègne
We introduce a novel method to study the fluid-structure interaction between a microcapsule and an external flow. A finite element method (for the membrane) is coupled with a boundary integral method (for the internal and external flows) to model the large deformation of the capsule. We find good agreement with previous results obtained with a solid solver based on the local equilibrium of the membrane.

16H00 : n° 673 Dynamique du décollement d'une vésicule en adhésion faible sur un substrat

Sunita Chatkaew Marc Georgelin Marc Léonetti
IRPHE, Aix-Marseille Université UMR CNRS 6594,
A l'équilibre thermodynamique, la forme d'une vésicule est régie par l'énergie de courbure, d'adhésion et son poids. La configuration expérimentale permet l'observation de sa forme et la mesure de l'épaisseur du film d'eau entre la membrane et le substrat. Avant la phase finale de décollement, deux régimes sont principalement observés en diminuant le volume réduit: une phase à aire de contact constante et épaississement du film ou bien une phase à forte diminution d'aire et épaisseur constante.

16H20 : n° 764 Measurement of the mechanical properties of alginate beads using ultrasounds

Anne-Virginie Salsac Liguo Zhang Jean-Marc Gherbezza
Université de Technologie de Compiègne
Alginate beads are one of the most common vehicles for encapsulation. When designing bioartificial organs, they are used as matrix for cell culture. Cell survival and activity depend essentially on the bead physical and mechanical properties. In this study, the mechanical properties of millimetric beads are evaluated using an ultrasound technique. We study the effects that the concentration in alginate has on the elastic properties of the beads. We show that density and stiffness coefficient of the bead are not independent. A measurement of the density can therefore provide a good estimation of the stiffness coefficient.

16H40 : n° 1459 A nano-micro-macro mechanical model for the analysis of soft collagenous tissues

Franco Maceri Michele Marino Guiseppe Vairo
Universita di Roma 'Tor Vergata'
In this paper the mechanical response of soft collagenous tissues with regular fiber arrangement (RSCTs) is described by means of a nanoscale model and a two-step micro-macro homogenization technique. The non-linear collagen constitutive behaviour is modelled at the nanoscale by a novel approach accounting for entropic mechanisms as well as stretching effects occurring in collagen molecules. Crimped fibers are reduced to equivalent straight ones at the microscale and the constitutive response of RSCTs at the macroscale is formulated by homogenizing a fiber reinforced material. This approach has been applied to different RSCTs (tendon, periodontal ligament and aortic media), resulting effective and accurate as proved by the excellent agreement with available experimental data. The model is based on few parameters, directly related to histological and morphological evidences and whose sensitivity has been widely investigated. Applications to simulation of some hysiopathological mechanisms are also proposed, providing confirmation of clinical evidences and quantitative indications helpful for clinical practice.