The mechanical properties of hydrogels involve solvent diffusion as well as viscous dissipation in the network, with the coupling called poroviscoelasticity. To explore the poroviscoelastic behavior, we performed tests on a gelatin-based hydrogel in which poroelastic swelling/drying occurred at controlled humidity levels while simultaneously developing creep deformation under a uniaxial load. These experimental results allowed the decomposition of the deformation into volumetric and isochoric parts, and the inference that volumetric deformation was dominated by poroelastic effects while isochoric deformation was influenced by both viscoelastic and poroelastic effects. We developed a nonlinear model based on an extension of the Flory–Rehner theory of the ternary system and the fractional derivative model of viscoelasticity to capture nonlinear poroviscoelastic behavior. The model was implemented into FEniCS finite element software. Comparisons of numerical simulations based on this model to experimental measurements were used to calibrate material parameters.

水凝胶的机械性能涉及网络中的溶剂扩散和粘性耗散，这种耦合称为多孔粘弹性。为了探索多孔粘弹性行为，我们对基于明胶的水凝胶进行了测试，其中在受控湿度水平下发生多孔弹性膨胀/干燥，同时在单轴载荷下产生蠕变变形。这些实验结果允许将变形分解为体积和等容部分，并推断体积变形受多孔弹性效应支配，而等容变形受粘弹性和多孔弹性效应影响。我们基于三元系统的 Flory-Rehner 理论的扩展和粘弹性的分数导数模型开发了一个非线性模型，以捕捉非线性多孔粘弹性行为。该模型被实现到 FEniCS 有限元软件中。基于该模型的数值模拟与实验测量的比较用于校准材料参数。