The porous nano-fibers raft: analysis of load-carrying mechanism and capacity

Abstract

A simple model of a raft made of spaced nano-cylinders is formulated and discussed, in order to improve the understanding of load-carrying capacity of insects and miniature devices that float on liquids. It is shown that mostly the outer cylinders of the raft determine the load-carrying capacity. Therefore, the raft porosity (spacing of the cylinders) is instrumental mainly in increasing the load-carrying capacity per unit weight of the raft. In addition, it is shown that the actual contact angle that the liquid makes with the surface of a cylinder does not necessarily have to be higher than 90° in order to support a load; therefore, the raft may support a load both on water and on oil. Nonetheless, the load-carrying capacity and the floating stability increase when the contact angle increases.