Soft materials such as hydrogels and elastomers exhibit very low stiffness and strength as well as large deformations, which makes their mechanical characterisation extremely difficult through conventional methods. This paper presents a novel experimental technique for the mechanical shear property characterisation of these materials. Agarose hydrogels were chosen as a model material for this study. The new in‐plane shear test method incorporates 3‐D‐printed acrylonitrile butadiene styrene (ABS) grips for specimen mounting and digital image correlation (DIC) for full‐field strain measurement on both sides of the specimen gauge section. These grips utilise barb‐like pegs to secure the specimen while load is applied. In order to evaluate the methodology, four concentrations of agarose hydrogel (4.0%, 2.5%, 1.5%, and 0.5% wt./solvent volume) were tested. Results for the agarose hydrogel demonstrated excellent repeatability. The obtained shear moduli show a monotonic increase with gel concentration. Furthermore, the range of shear moduli applicable to the novel testing method was determined.

中文翻译：

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改进的用于软质胶状和弹性体材料的直接剪切表征技术

软质材料（例如水凝胶和弹性体）显示出非常低的刚度和强度以及较大的变形，这使得通过常规方法很难对其进行机械表征。本文介绍了一种新颖的实验技术，用于表征这些材料的机械剪切性能。选择琼脂糖水凝胶作为该研究的模型材料。新的面内剪切测试方法结合了3D打印的丙烯腈丁二烯苯乙烯（ABS）夹具，用于样品安装，而数字图像关联（DIC）用于在样品量规部分的两侧进行全场应变测量。这些夹具利用倒钩状的钉子在施加载荷时固定样品。为了评估该方法，四种浓度的琼脂糖水凝胶（4.0％，2.5％，1.5％和0.5％wt。/溶剂体积）进行测试。琼脂糖水凝胶的结果显示出极好的可重复性。所获得的剪切模量随凝胶浓度显示单调增加。此外，确定了适用于该新型测试方法的剪切模量范围。