Nanomechanical and Angle-dependence Optical Properties in Beetle Popillia Indgigonacea Motsch (Coleoptera)

Beetle cuticles are light weight with high strength, and some beetles are able to change its coloration during the process of growing. In this study, the relationship between nanomechanical properties and microstructures of elytra of irreversibly color-changing Sagra femorata purpurea lichtenstein were investigated, and the bionic architectures based on its elytron which are light weight with high strength were designed for mechanical simulation. The surface morphology of elytron was obtained by confocal laser scanning microscopy (CLSM). The interior microstructures of beetle elytra were stained and then observed by high power microscope used in medical science. Nanomechanical properties of transverse and longitudinal sections of beetle elytra were investigated through nanoindentation tests. Then finite element analysis was used to illustrate the difference of mechanical properties between these two kinds of models with different microstructures on the surface that undergo irreversible color-changing. The elytron of S. lichtenstein not only plays irreversible color-changing by surface morphology but also performs high strength with light weight interior microstructure. This work will lay the foundation for designing new component materials with bionic structures and color-changing ability.