Capillary-condensation-induced stress in complex multi-scale porous materials

The adsorption/desorption isotherms in porous media is a powerful and widely-
adopted method to probe the pore size distribution and connectivity of the pore
network. Despite the importance of the isotherms, the picture of capillary conden-
sation in a single infinitely long pore of simple geometries (slit, cylinder, etc.) and
the corresponding hysteresis loop is not sufficient to quantitatively predict the ex
perimental results which are measured in highly connected, irregularly shaped and
3D pore networks. We developed a parallelized numerical scheme
to simulate the liquid distribution during adsoprtion/desorption processes in these
multi-scale porous structures. Moreover adsorption provides mechanical feedback on
the solid porous structure, which induces measurable deformations, sometimes quite
dramatic structural changes such as in drying shrinkage experiments. We pinpoint
the connection of lattice models with phase-field models and propose a novel and gen-
eral framework to calculate the capillary stress distribution inside the porous network.
We adopt the Love-Weber homogenization scheme to analysis the effect of capillary
stress in complex porous structures on different scales: both the macroscopic isotropic
and homogeneous effect and the mesoscopic heterogeneous stress distributions.