Hydrogels have a wide range of applications from medical devices to tissue engineering to industrial health products. The numerical modeling of these porous structures can provide insight into their in-situ performance. However, an accurate constitutive model to replicate the stress-strain behavior of the swelling process is essential in ensuring the efficacy of the simulation. This study presents a strain dependent constitutive model for describing the finite deformation of superabsorbent polymers undergoing solvent induced swelling. Like many elastic materials, stretch-induced softening and hardening of these polymers occurs at large deformations. In order to incorporate the deformation dependent modulus into the new model, the shear modulus of sodium polyacrylate gels were measured using a rheometer as a function of swelling. Through numerical simulations on spherical gels, the effect of both cross-link density and the dependent modulus is investigated against a control model. As experimental quantification of the initial porosity is difficult and often not consistent between samples, Monte-Carlo simulations are implemented to experimentally verify the new model. Furthermore, this model is applied to experimental uniaxial tension data of incompressible rubber to allow comparison to other strain hardening constitutive models.

水凝胶具有广泛的应用范围，从医疗设备到组织工程再到工业保健产品。这些多孔结构的数值模型可以提供对其原位性能的了解。但是，复制膨胀过程的应力应变行为的精确本构模型对于确保模拟的有效性至关重要。这项研究提出了一种应变相关的本构模型，用于描述超吸收性聚合物经历溶剂诱导溶胀的有限变形。像许多弹性材料一样，这些聚合物在大变形时会发生拉伸诱导的软化和硬化。为了将依赖于变形的模量纳入新模型，使用流变仪测量聚丙烯酸钠凝胶的剪切模量与溶胀的关系。通过对球形凝胶的数值模拟，对照对照模型研究了交联密度和相关模量的影响。由于样品之间的初始孔隙率很难进行实验量化，而且常常不一致，因此采用蒙特卡洛模拟来实验验证新模型。此外，该模型被应用于不可压缩橡胶的实验单轴拉伸数据，以便与其他应变硬化本构模型进行比较。