Constitutive modeling for polymer hydrogels: A new perspective and applications to anisotropic hydrogels in free swelling
Constitutive modeling for polymer hydrogels: A new perspective and applications to anisotropic hydrogels in free swelling
复制标题
聚合物水凝胶的本构模型：自由膨胀各向异性水凝胶的新视角和应用
DOI：
10.1016/j.euromechsol.2015.07.001
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发表时间：
2015-11-01
影响因子：
4.1
通讯作者：
Zheng, Yonggang
中科院分区：
文献类型：
--
作者：
Liu, Yin;Zhang, Hongwu;Zheng, Yonggang
本文提出了一种修正的水凝胶稳态和瞬态各向同性和各向异性变形的理论框架。利用热力学第二定律中力学场和化学场之间的运动约束，可以得到一个统一的本构方程，该方程能够同时描述水凝胶的各向同性或各向异性变形。在此基础上对溶剂分子的扩散方程进行了修正，避免了在自由能函数中引入拉格朗日乘子来强制约束。建立了描述各向异性水凝胶稳定膨胀行为的理论框架，并讨论了相应的自由膨胀方程的解性质。研究了几种构型的各向异性膨胀行为，包括水凝胶块和含有一族或两族增强纤维的圆柱形管。我们发现各向异性水凝胶在自由状态下的膨胀表现出丰富的行为，如选择性膨胀/收缩和异常残余应力。横向各向同性膨胀的本构方程计算结果与实验结果吻合，证明了本构模型的有效性。(C) 2015 Elsevier Masson SAS。版权所有。
The paper presents a modified theoretical framework for isotropic and anisotropic deformation of hydrogels in both steady and transient states. By applying the kinematic constraint between the mechanical and chemical fields in the second law of thermodynamics, a unified constitutive equation could be obtained, which is capable to describe the isotropic or anisotropic deformation of hydrogels at the same time. Also, the diffusion equation for solvent molecules is modified based on the constraint and the Lagrange multiplier used to force the constraint is avoided being introduced in the free energy function. The theoretical framework is specialized to describe the steady swelling behaviors of anisotropic hydrogels and the corresponding solution properties for the equations of free swelling are discussed. The anisotropic-swelling behaviors for several kinds of configurations are investigated, including hydrogel blocks and a cylindrical tube with one or two families of reinforced fibers. We find that the swelling of anisotropic hydrogels shows rich behaviors even for the simple configurations in free states, such as selective expansion/shrinkage and anomalous residual stress. An agreement between the results obtained by the constitutive equations and experiments for the transversally isotropic swelling demonstrates the effectiveness of the constitutive model. (C) 2015 Elsevier Masson SAS. All rights reserved.