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Adhesion of flat-ended pillars with non-circular contacts.
Soft Matter ( IF 2.9 ) Pub Date : 2020-08-31 , DOI: 10.1039/d0sm01105c
Aoyi Luo 1 , Amir Mohammadi Nasab 2 , Milad Tatari 2 , Shuai Chen 3 , Wanliang Shan 3 , Kevin T Turner 1
Affiliation  

Fibrillar adhesives composed of fibers with non-circular cross-sections and contacts, including squares and rectangles, offer advantages that include a larger real contact area when arranged in arrays and simplicity in fabrication. However, they typically have a lower adhesion strength compared to circular pillars due to a stress concentration at the corner of the non-circular contact. We investigate the adhesion of composite pillars with circular, square and rectangular cross-sections each consisting of a stiff pillar terminated by a thin compliant layer at the tip. Finite element mechanics modeling is used to assess differences in the stress distribution at the interface for the different geometries and the adhesion strength of different shape pillars is measured in experiments. The composite fibrillar structure results in a favorable stress distribution on the adhered interface that shifts the crack initiation site away from the edge for all of the cross-sectional contact shapes studied. The highest adhesion strength achieved among the square and rectangular composite pillars with various tip layer thicknesses is approximately 65 kPa. This is comparable to the highest strength measured for circular composite pillars and is about 6.5× higher than the adhesion strength of a homogenous square or rectangular pillar. The results suggest that a composite fibrillar adhesive structure with a local stress concentration at a corner can achieve comparable adhesion strength to a fibrillar structure without such local stress concentrations if the magnitude of the corner stress concentrations are sufficiently small such that failure does not initiate near the corners, and the magnitude of the peak interface stress away from the edge and the tip layer thickness are comparable.

中文翻译:

具有非圆形触点的平端支柱的粘合。

由具有非圆形横截面和接触的纤维(包括正方形和矩形)组成的原纤维粘合剂具有以下优点:排列成阵列时具有更大的实际接触面积,并且制造简单。但是,由于应力集中在非圆形触点的角部,因此与圆形支柱相比,它们的粘合强度通常较低。我们研究了具有圆形,方形和矩形横截面的复合柱的粘附力,每个复合柱都由一个刚性柱构成,该柱在尖端处被薄的柔顺层终止。有限元力学建模用于评估不同几何形状的界面处应力分布的差异,并在实验中测量不同形状支柱的附着强度。复合的原纤维结构在粘附的界面上产生了有利的应力分布,对于所有研究的横截面接触形状,该分布都使裂纹萌生部位从边缘移开。在具有各种尖端层厚度的方形和矩形复合支柱中,获得的最高附着强度约为65 kPa。这可与圆形复合材料支柱的最高强度相比,并且比均质方形或矩形支柱的附着强度高约6.5倍。
更新日期:2020-09-23
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