Multi-scale mechanical modelling of starchy materials and foods using the finite element method

In addition to confirming the poor adhesion between constituents, simulation of this test using a finite element model (FEM) demonstrates the discontinuity of deformation at the interface [20]. The presence of adhesion defects explains the difference between the elastic moduli calculated by an FEM model applied to virtual microstructures of these two-phase mixtures and the results measured by 3-point bending [3]. The introduction into the numerical model of an interphase region, defined by its modulus and thickness, which are functions of the zein content, makes it possible to adjust the experimental results of the composite moduli [12]. The explicit effect of the interface is implemented at the microstructure scale to give the effective properties of the composite [6]. Although these properties cannot be generalised to the macroscopic scale because of structural heterogeneity, these results together pave the way for the design of composite material microstructures based on biopolymer blends with targeted mechanical properties.

For the same compositions, the experimental production of products with different cell structures but the same density is still a challenge. Their mechanical behaviour is therefore simulated using numerical modelling (FEM) based on tomographed or virtual honeycomb structures produced by random sequential stacking (RSA) of spheres, to determine the impact of this characteristic on the elastic modulus, This makes it possible to enrich the cellular solids model (Gibson-Ashby), and to show that cellular heterogeneity increases, for an imposed porosity, the mechanical rigidity of food foams, as in the case of breadcrumbs [21] and extruded starches [34]. The same approach, applied to anisotropic honeycomb structures present in extruded products [x1], highlights the importance of honeycomb orientation and shape on elastic properties [5, 22].