Micro structures and nano mechanical properties of beetle Sophrops elytra
1.School of Mechanical Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China; 2.Institute of Bioinspired Structure and Surface Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu 210016, China
Abstract:The micro structures of elytra were observed by scanning electron microscopy(SEM), and the nano mechanical properties of elytra were determined
and analyzed by nano indentation machine. The SEM images show that the elytra of Sophrops has empty laminate structure with dorsum, lumen and abdomen, which guarantees the light-weight characteristic of elytra with enough strength. On microscopic scale, the elytra shows non-smooth surface texture. The hardness and the modulus of elytra exocuticle by nano indentation tests are H of 0.48 GPa and Er of 8.81 GPa, respectively. The specific stiffness and the specific modulus are 600 MPa/(g·cm-3)-1 and 1.1×104 MPa?(g?cm-3)-1, respectively. The contact stiffness (K) of (2.28±0.16)×104 N?m-1 indicates excellent capability of deforming resis-tance. The nano mechanical properties of elytra are anisotropic with the maximum near sutual edge and the minimum at verge zone. The mechanical properties decrease gradually from cephalosome zone to empennage zone of elytra.