Constitutive modeling of visco‐hyperelastic behavior of double‐network hydrogels using long‐term memory theory

Abstract

Double-network hydrogels with viscoelastic behavior are appropriate materials for biomechanical applications. In this article, the standard linear solid (SLS) rheological model for the linear viscoelastic materials is generalized to the viscoelastic materials with large nonlinear deformations. Based on this viewpoint, the constitutive equation is proposed as sum of two parts including the straindependent elastic stress, and the viscous stress, which depends on the strain and strain rate. The elastic part of the stress is modeled via considering a hyperelastic strain energy function, while the main core of the viscous stress part requires a time-dependent weight function to satisfy the long-term memory fading principle. In addition, the weight function is proposed such that it can capture the mechanical behavior trend corresponding to the strain and strain rate for a double-network hydrogel in the relaxation test. Finally, to evaluate the performance of the proposed constitutive equation for the mechanical behavior modeling of double-network hydrogels, the tests on these materials have been used, and the material parameters are determined from fitting the experimental results to the theory. The agreement of test and theory results showed that the proposed model is capable to model the mechanical behavior of double-network hydrogels.

Predicting the hyperelastic properties of alginate-gelatin hydrogels and 3D bioprinted mesostructures

“…Especially when mechanical testing involves large deformations, it is necessary to use nonlinear material models. We focus only on time-independent properties and thus neglect viscoelastic effects 39 , 40 . To the best of our knowledge, few research has been done on the hyperelastic material characterization of hydrogels in the 3D bioprinting field.…”

Tuning the viscoelastic response of hydrogel scaffolds with covalent and dynamic bonds

“…Development of constitutive models for the elastic, viscoelastic and viscoplastic responses of double-network gels with supramolecular and dynamic covalent cross-links has attracted noticeable attention in the past decade (Liu et al, 2016;Mao et al, 2017;Drozdov and deClavill Christiansen, 2018a,b;Lu et al, 2018;Yu et al, 2018;Khiem et al, 2019;Lin et al, 2020;Javadi et al, 2021;Xiao et al, 2021), see also reviews (Guo and Long, 2020;Xiang et al, 2020;Lei et al, 2021). Unlike previous studies, we focus on derivation of constitutive equations with the minimum number of material parameters.…”