Bio-bearings: Numerical Model of the Solid Lubricant in the Leg Joints of Insects

The proposed model describes the behavior of the lubricant particles at the interface between two surfaces for a group of cylindrical semi-solid lubricant fragments observed in a real beetle leg joint. It is shown that the lubricant particles may maintain a gap between joint surfaces at load. At the regular shear motion, such randomly oriented particles are reorienting perpendicular to the shear and function as a rolling bearing: the system demonstrates the lowest energy loss and lowest friction. At an increased load, the friction non-linearly increases, because of an increase of the particles’ eccentricity. Finally, at some load, the particle rotation stops, friction switches from the rolling to the sliding regime and increases significantly.