(182c) Investigation of Mechanical Properties of Femur and Tibia Articulations of Insect Joints

Insects have more than a million described species and represent more than half of all known living organisms. However, little is known about the operation and functions of the insect body, particularly their remarkable leg joints. This work is focused on partly filling this knowledge gap by systematically studying the mechanical and structural properties of insect joints associated with legs of varying functions. This work focuses on the investigation and comparison of the elastic modulus of terrestrial cursorial beetle, terrestrial raptorial mantis, and aquatic cursorial dragonfly nymph insect legs via nanoindentation studies. It was found that the sheared joint surfaces showed no sign of wear or damage, even though they had undergone thousands of external shearing cycles. We attribute their resiliency to a synergistic interaction between the hierarchical surface texture/pattern on the femoral surfaces, a nanograded internal nanostructure of articulating joints, and the presence of lubricating lipids on the surface at the joint interface. The micro/nanopatterned surface of the leg femur-tibia joint enables a reduction in the total contact area, and this significantly reduces the adhesive forces between the coupling surfaces.