Mechanical behavior of PVA hydrogels over a wide strain rate range and a new two-phase visco-hyperelastic constitutive model

PVA hydrogels, as potential substitutes for soft biological tissues, are valuable in biomedical applications. However, studies on mechanical behavior at 100-500/s are scarce, where the inflection point of strain rate effect lies, prompting the utilization of bilinear models with inaccuracies. To improve accuracy, we developed a Hopkinson bar for ultra-soft materials and conducted experimental studies on PVA hydrogels at various strain rates. A new visco-hyperelastic model that incorporates the polymer network and water phases was developed and verified by experimental data. It captures both strain rate effects and water loss, providing insights for hydrogels and soft biomaterials.