Résumé
Based on the use of shell kinematics, a theoretical model is developed to predict time-dependent responses of Saccharomyces cerevisiae yeasts. These cells are herein described as thin-walled shells with axisymmetrical shapes and, due to their soft nature, the finite strain range is a priori assumed. Accordingly, a finite viscoelastic modeling is assumed for the cell-wall. An Ogden-type energy function is adopted together with a creep-like potential, this latter to describe the way overstresses vanish at thermodynamic equilibrium. The cell-volume conservation due to the inner incompressible fluid is accounted for via an update procedure of the Uzawa type. Baker's yeast-wall is assumed to be homogeneous and isotropic in a first approach. However, it seems that this simplification is too questionable. The necessity of a cell-wall representation by at least two sets of layers with sensitively different mechanical properties is established. Nanoindentation by atomic force microscopy must be complemented with micromanipulation experiments for a better characterization of the now heterogeneous cell-wall. Numerical simulations highlight the efficiency of the proposed framework.