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摘要
This paper aims to study the size- and shape-dependent steady-state pull-off force in molecular adhesion between two soft elastic materials. The adhesion consists of a patch of non-covalent bonds formed between ligand and receptor molecules on opposing adhesion surfaces. Classical contact mechanics is used to model the deformation of elastic materials while Bell's model is adopted to describe stochastic breaking/reforming of molecular bonds. A coupled elastic-stochastic model is established to show that there exists a critical adhesion size, which leads to a critical stress concentration index after proper normalization, beyond which stress concentration near the contact edge causes crack like failure of the adhesion patch governed by Griffith's criterion and below which the pull-off traction is saturated at a constant strength governed by Bell's model of molecular adhesion. In addition to size effect, optimal adhesion can also be achieved by designing the shape of the contact surfaces, although it is sensitive to small variations in shape at large adhesion size or stress concentration index. A robust, shape-insensitive high-strength adhesion state becomes possible when the adhesion size or the stress concentration index is sufficiently small.
- 出版日期2010-11
- 单位兰州大学
