Center for Mechanics of Solids, Structures and Materials, Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, TX 78712, USA.
Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX 78712, USA.
J R Soc Interface. 2017 Oct;14(135). doi: 10.1098/rsif.2017.0377.
It has been shown experimentally that cratered surfaces may have better adhesion properties than flat ones. However, the suction effect produced by the craters, which may be chiefly responsible for the improved adhesion, has not been properly modelled. This paper combines experimental, numerical simulation and analytical approaches towards developing a framework for quantifying the suction effect produced by isolated craters and cratered surfaces. The modelling approach emphasizes the essential role of large elastic deformation, while the airflow dynamics, microscopic mechanisms, like surface tension and air permeation, and rate-dependence are neglected. This approach is validated using experimental data for isolated hemi-spherical craters. The modelling approach is further applied to spherical cap (not necessarily hemi-spherical) craters with the objective of identifying optimal geometric and material properties, as well as the minimum preload necessary for attaining the maximum suction force. It is determined that stiff polymers with deep craters are capable of producing large suction forces. For soft materials, central to biomedical applications, large suction forces can be attained by reinforcing deep craters with thin stiff layers. Parametric optimization studies of reinforced craters reveal that some of them perform beyond common expectations. However, those high-performance reinforced craters are prone to surface instabilities, and therefore the practical use of such craters may be problematic.
实验表明，有坑洼的表面可能比平坦的表面具有更好的附着力。然而，主要负责提高附着力的坑洼所产生的吸力效应尚未得到适当的建模。本文结合实验、数值模拟和分析方法，为量化孤立坑洼和坑洼表面产生的吸力效应建立了一个框架。该建模方法强调了大弹性变形的重要作用，而忽略了气流动力学、微观机制（如表面张力和空气渗透）以及速率相关性。该方法通过对孤立的半球形坑洼的实验数据进行验证。该建模方法进一步应用于具有球形帽（不一定是半球形）坑洼的情况，目的是确定最佳的几何和材料特性，以及为获得最大吸力所需的最小预紧力。结果表明，具有深坑洼的硬聚合物能够产生较大的吸力。对于生物医学应用中至关重要的软材料，可以通过在深坑洼中添加薄的硬层来获得较大的吸力。对加固坑洼的参数优化研究表明，其中一些坑洼的性能超出了预期。然而，这些高性能的加固坑洼容易出现表面不稳定性，因此这些坑洼的实际应用可能存在问题。
