Mechanical Model And Numerical Simulation Of Gecko Hyperextension

There are a wide range of needs in civil, aerospace and military field for wall-climbing robot. And one of the key problems is the design of adhesion system. The robot relied on the intermolecular force which has the advantage of independent from material and roughness has a good prospect. Gecko has been the ideal object for its outstanding climbing ability. With the help of hyperextension of the toe, gecko detached from the substrate rapidly and with low impact. But the mechanics of hyperextension has not been clear yet, and the study on its mechanics will help the design of bio-inspired adhesive and wall-climbing robot.Firstly, the experiment was designed to measure forces when toe hyperextended. The gecko was anaesthetized, and was hanged on a vertical glass with one toe. With the help of neuroscience, the neural stem corresponding to the attachment and detachment was stimulated by electric current, the hyperextension occurred in experiments. And the mechanical data and behavior were acquired through three-dimensional mechanics data acquisition system and high speed video system, respectively. The data shows that detachment was divided into two phase: in the first phase, only normal force increased, while the tangential force kept constant. In the second phase, the normal force remained unchanged approximately, and tangential forces increased. The peak normal was higher than the initial normal force about 21 m N. When adhesion length was less than the detachment length, the normal and tangential forces decayed rapidly.Secondly, the continuous detachment model, non-continuous detachment model, piecewise non-continuous detachment models were built in ABAQUS. And the behavior and mechanics in hyperextension and 30°peeling were analyzed using the finite element method. The time and normal impulse of hyperextension is smaller than 30° peeling. Smaller normal impulse means a smaller impact.Finally, the continuous adhesive elastic tape and non-continuous fibers elastic tape model were built, which were simplified into flexible beam in moment and forces. The detachment constant was taken as the failure criterion; the critical detachment moment was deduced.