Advanced Experimental Mechanics
Online ISSN : 2424-175X
Print ISSN : 2189-4752
ISSN-L : 2189-4752
Solid Mechanics and Materials Engineering
Evaluation of the Effects of Cross-Link Density and Swelling Ratio on Loading-Unloading Response in Large Strain Range of Hydrogels
ジャーナル フリー

2022 年 7 巻 p. 90-96


Hydrogel contains a large amount of solvent such as water inside a three-dimensional molecular chain network structure. The content of the solvent changes during the swelling and drying processes of the hydrogel. The mechanical properties of the gel significantly change depending on the solvent content. In this study, the effects of the cross-link density and swelling ratio on the nonlinear mechanical responses of hydrogel were investigated by the cyclic tensile test. To evaluate the irreversible deformation of the hydrogel, we performed the one-time and stepwise loading-unloading tests. The stress-strain curves for the loading and unloading process obtained from the crosshead displacement were different owing to the sliding between chuck and specimen. In contrast, they were consistent for all the experimental conditions when the strain was evaluated by the digital image correlation method. Therefore, the hydrogel showed the less-rate-dependent reversible deformation from small to large strain range. Furthermore, obtained results were compared with the theoretical model based on the molecular chain network model with swelling effect. Although the model could represent the nonlinear increase in the stress during the tensile test and the decrease in the stiffness owing to the swelling, the model results were not consistent with the experimental results. Experimental and numerical results indicate that the improvement of the mechanical model is necessary based on the less-rate-dependent reversible deformation mechanisms of the hydrogel.

© 2022 The Japanese Society of Experimental Mechanics
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