Research On The Mechanism And Application Of The Gecko-inspired Adhesives

The bio-inspired technology has inspired lots of important inventions and greatlychanged the society of the human being. With outstanding capability of adhesion andfriction control, gecko can move on the surfaces of the walls and ceilings rapidly. Thegecko-inspired functional surface and then the wall-climbing robot have great potentialand wide application prospect in the area of national security, industry and daily lifesuch as counter-terrorism, rescue, detection, space positioning, cleaning in tall buildings,etc. Therefore, the research on the mechanism of attachment and detachment and thedesign principles are very important to developing the new generation of dry adhesivefunctional surface and device in both theoretical and practical applications. Based on theeffect of peel zone on the peeling behavior and the anisotropic property, the principle ofdesign and application of bio-inspired surface has been researched in this study.First, the basic theoretical peel zone model is developed, with the consideration ofthe peel velocity effect. Peel strength, peel velocity and peel angle, the three importantpeeling parameters, are described in the same analytical formula by the extended peelzone model.Second, the design principle of bio-inspired surface with the strong attachment buteasy removal properties and the anti-bunching behavior are developed. A numericalmethod was developed to evaluate the effect of peel-zone deformation on the peelingbehavior of fibrillar gecko-inspired surface. Based on the analysis of the peelingmechanical behavior, the design criterion of strong attachment and easy removalproperties is discussed. The optimum point is proposed by a new established adhesionand peeling design map, which is determined by the competition of the strong adhesiveproperty and the easy-removal property, being consistent with the allowed parameterrange of the biological contact elements qualitatively. By taking the typical values ofparameters, the adhesion force and the peeling strength can be changed in three ordersof magnitude. Further, the bunching behavior of micro-and nano pillar array surface isstudied. The two dimensionless parameters are proposed to evaluate the criterion ofbunching. Also the evaluation criterion of the stability of bunching is established.Then in order to discuss the relationship between the anisotropy and thedeformation of the peel zone, the gecko-inspired surface is prepared with inclined multiwall carbon nanotube array, which has typical40%steady anisotropic interfacialfriction property. The tribological characterization of the inclined CNT array surface istested experimentally. Also the anisotropic adhesional friction is observed in theunloading process. Furthermore, the anisotropic behavior is quantitatively modeled andexplained based on the van der Waals interaction.Finally, a prototype of clamp holder based on gecko-inspired surfaces has beendesigned and tested. On the basis of the experimental mechanical characterization andthe theoretical design evaluation of the mushroom like fibrillar gecko-inspired surface,the clamp holder designed specifically to the lightweight and fragile objects is realizedand fabricated, which provides new insights into the application of gecko-inspiredsurface on the intelligent adhesion devices.