Research of Bio-nano-chitin-fiber Structures of Chafer Cuticle

摘要

Insect cuticle possesses high strength and high fracture toughness. The superior material properties are closely related to the various particular nanostructures in the cuticle, which has passed through natural optimization for thousands of years. In this work, a Scanning Electron Microscope (SEM) was used for observing the various nanostructures in a chafer cuticle. The observation revealed corkscrew and branched fiber nanostructures in the cuticle. The toughness mechanisms of these nanostructures were investigated with their representative models. The fracture toughness of the specimens with the corkscrew fiber structure was tested and compared with that of the specimens with 0°structure. It showed that the fracture toughness of the specimens with the corkscrew structure is markedly larger than that of the specimens with 0° structure. The maximum pullout force of the branched fiber structures was also tested and compared with that of conventional straight fiber structure, and it showed that the maximum pullout force of the branched fiber structure is larger than that of the conventional straight fiber structure. At last, the advantage of the fibers of nanometer scale was analyzed with an empirical formula of energy dissipation during fiber-pull-out from matrix. It showed that the fibers of nanometer scale can increase the dissipation energy when they are pulled out from matrix, which enhance the fracture toughness of the cuticle.