silk cocoon (bombyx mori): multi-layer structure and mechanical properties

bombyx mori cocoon is a natural composite made of silk fibre with a distinctive multi-layer structure that provides mechanical protection for its biological functions. here we investigate the components, structure and mechanical properties of cocoon layers, and quantify the contributions of the multi-layer structure to the mechanical properties of cocoon. a better understanding of the multi-layer mechanism of a natural composite could help the further design of biomimetic multiscale artificial materials.