| ZHANG Jin-hong,SHI Kui,XU Peng,LI Qian,XUE Long-jian.The Dynamic Regulation of Friction Force of a Water Droplet on Goose Bumps-inspired Surfaces[J],50(8):66-73, 83 |
| The Dynamic Regulation of Friction Force of a Water Droplet on Goose Bumps-inspired Surfaces |
| Received:April 27, 2021 Revised:July 05, 2021 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2021.08.006 |
| KeyWord:surface wettability contact angle sliding angle friction force MPCP bioinspiration |
| Author | Institution |
| ZHANG Jin-hong |
School of Power and Mechanical Engineering, Wuhan University, Wuhan , China;Department of Mechanical Engineering, Shanxi Polytechnic College, Taiyuan , China |
| SHI Kui |
School of Power and Mechanical Engineering, Wuhan University, Wuhan , China |
| XU Peng |
School of Power and Mechanical Engineering, Wuhan University, Wuhan , China |
| LI Qian |
School of Power and Mechanical Engineering, Wuhan University, Wuhan , China |
| XUE Long-jian |
School of Power and Mechanical Engineering, Wuhan University, Wuhan , China |
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| Abstract: |
| In this paper, mechanical stretching and relaxation are used to realize the dynamic control of the roughness of goose bumps-inspired surfaces, and capillary projection sensing technology (MPCP) is used to quantitatively characterize the friction force of droplets on simulated goose bumps, revealing the detailed motion characteristics of droplets on solid surfaces. The surface of polydimethylsiloxane (PDMS) mixed with polystyrene (PS) beads is prepared to imitate the goose bumps of human body. Due to the difference of modulus, PS beads protrude from the surface under external tension, which leads to the increase of surface roughness and mimics the stress response of goose bumps in human body. When the tension is removed, "goose bumps" disappear. The reversible adjustment of the roughness of surface microstructure is thus realized. At the same time, capillary projection sensing technology is used to quantitatively characterize the friction force of liquid droplets on planar and striped surfaces, and the effects of stretching amount, stretching direction, droplet volume and moving speed on the friction force of liquid-solid interface are discussed in detail. With the increase of stvetching, the number and height of PS beads protruding from PDMS surface increases, which increases the surface roughness and reduces the friction force. However, the frictional forces in the stretching direction (DS) and the vertical direction (DV) are different, showing anisotropy. With the increase of droplet size, the frictions in DS and DV directions increase. In the test range, the influence of droplet moving speed on the friction force of liquid-solid interface can be neglected. The friction force of solid surface is quantitatively characterized by capillary projection sensing technology, which reveals the function law of liquid-solid interface that could not be revealed by rolling angle test. |
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