Abstracts Category : Other

Structure-property relations of the exoskeleton of the ironclad beetle (Zopherus nodulosus haldemani)

by Vina Le Nguyen

In this study, structure-property relationships in the ironclad beetle (Zopherus nodulosus haldemani) exoskeleton are quantified to develop novel bio-inspired impact resistance technologies. The hierarchical structure of this exoskeleton was observed at various length scales for both the ironclad beetle pronotum and elytron. The exocuticle and endocuticle layers provide the bulk of the structural integrity and consist of chitin-fiber planes arranged in a Bouligand structure. The pronotum consists of a layered structure, while elytron consists of an extra layer with tunnel-like voids running along the anteroposterior axis along with smaller interconnecting tunnel-like voids in the lateral plane. Energy dispersive X-ray diffraction revealed the existence of minerals such as calcium carbonate, iron oxide, zinc oxide, and manganese oxide. We assert that the strength of this exoskeleton could be attributed to its overall thickness, the epicuticle layer thickness, the existence of various minerals embedded in the exoskeleton, and its structural hierarchy. The thickness of the exoskeleton correlates to a higher number of chitin-fiber planes to increase fracture toughness, while the increased thickness of the epicuticle prevents hydration of the chitin-fiber planes. In previous studies, the existence of minerals in the exoskeleton has been shown to create a tougher material compared to non-mineralized exoskeletons. Advisors/Committee Members: RajKumar Prabhu (committee member), Lakiesha N. Williams (committee member), Hongjoo Rhee (committee member), Mark F. Horstemeyer (committee member).