Effect of Microscale Contact State of Polyurethane Surface on Adhesion and Friction

• Published in: Journal of bionics engineering Vol. 3; no. 2; pp. 87 - 91
• Main Authors: Yu, Min, Ji, Ai-hong, Dai, Zhen-dong
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.06.2006; Institute of Bio-inspired Structure and Surface Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, P. R. China
• Subjects: adhesion; friction; polyurethane; rough surface; 仿生学; 微尺度接触状态; 摩擦力; 粗糙表面; 粘附力; 聚亚氨酯; rough surface; polyurethane; adhesion; friction
• ISSN: 1672-6529; 2543-2141
• DOI: 10.1016/S1672-6529(06)60012-7

The effect of microscale contact of rough surfaces on the adhesion and friction under negative normal forces was experimentally investigated. The adhesive force of single point contact - sapphire ball to flat polyurethane did not vary with the normal force. With rough surface contact, which was assumed to be a great number of point contacts, the adhesive force increased logarithmically with the normal force. Under negative normal force adhesive state, the tangential force （more than hundred mN） were much larger than the negative normal force （several mN） and increased with the linear decrease of negative normal force. The results reveal why the gecko＇s toe must slide slightly on the target surface when it makes contact on a surface and suggest how a biomimetic gecko foot might be designed.