Poroviscoelasticity and fracture in gelatin-based hydrogels

Hydrogels are network polymers with water as the primary embedded solvent. The mechanical properties of such hydrogels involve solvent diffusion as well as viscous dissipation in the network. We explore experiments in which poroelastic swelling/drying occurs at controlled humidity levels, while simultaneously subjecting the material to creep deformations. These experimental results allowed the decomposition of volumetric and deviatoric deformation histories and the inference that while the volumetric deformation was dominated by poroelastic effects, the deviatoric deformation was significantly influenced by the volumetric deformation. Numerical simulations of the experiments with an assumed form of the poro-visco-elastic constitutive model are used to develop a calibration of the nonlinear model parameters and to interpret the fracture behavior of hydrogels.