Poynting and reverse Poynting effects in soft materials
Poynting and reverse Poynting effects in soft materials
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DOI：
10.1039/c7sm00992e
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发表时间：
2017-07-28
期刊：
影响因子：
3.4
通讯作者：
Murphy, J. G.
中科院分区：
文献类型：
--
作者：
Horgan, C. O.;Murphy, J. G.
1909年，J. H.波印廷对金属线进行了一系列实验，发现加载的金属线在扭曲时会变长。因此，为了在此类实验中保持恒定的长度，需要在样本的端部施加压缩轴向力。这就是经典的（正）坡印廷效应。这种效应的另一个例子是当软材料试样在两个压板之间被轴向剪切或旋转时。为了保持压板之间的相对距离而施加法向力的必要性通常也被称为坡印亭型效应。这两种效应本质上都是非线性现象。在最近的论文中，已经报道了软固体中坡印廷效应的实验数据。Janmey等人的开创性论文描述了水凝胶的剪切实验，水凝胶浸渍有硬蛋白，如胶原蛋白和纤维蛋白。结果表明，正和负（反向）坡印亭效应可能发生。在这篇论文和几位作者的后续论文中，利用包括嵌入软基质中的半柔性长丝的增强纤维的微观结构来检查法向应力的特征。本文的目的是描述和审查的替代方法，使用基于非线性连续介质力学的超弹性宏观唯象理论。我们的目的是证明，这样的理论可以用在一个非常透明的方式来预测发生的正和负坡印亭效应在各向异性软纤维材料。可以看出，材料各向异性在分析中起着关键作用。
In 1909, J. H. Poynting conducted a series of experiments on metal wires and found that loaded wires lengthen when twisted. Thus to maintain a constant length in such experiments, a compressive axial force would need to be applied at the ends of the specimen. This is the classical (positive) Poynting effect. Another example of such an effect arises when a soft material specimen is being axially sheared or rotated between two platens. The necessity to apply a normal force in order to maintain the relative distance between the platens is also often referred to as a Poynting-type effect. Both effects are inherently nonlinear phenomena. In recent papers, experimental data on the Poynting effect in soft solids have been reported. The seminal paper by Janmey et al. describes shearing experiments on hydrogels, impregnated with scleroproteins such as collagen and fibrin. It was shown that positive and negative (reverse) Poynting effects could occur. In this and subsequent papers by several authors, the microstructure of reinforced biogels involving semi-flexible filaments embedded in a soft matrix was exploited to examine the character of the normal stresses. The purpose of the present paper is to describe and review an alternative approach using the macroscopic phenomenological theory of hyperelasticity based on nonlinear continuum mechanics. Our aim is to demonstrate that such a theory can be used in a very transparent way to predict the occurrence of both positive and negative Poynting effects in anisotropic soft fibrous materials. It will be seen that material anisotropy plays a key role in the analysis.