The flexural properties of end-trabecular beetle elytron plates and their flexural failure mechanism

In pursuit of the development of lightweight biomimetic functional–structural materials, this study investigated the flexural properties and failure characteristics of end-trabecular beetle elytron plates (EBEPs) as well as the flexural mechanism and the role of the trabeculae. The results were as follows: (1) The EBEP specimens showed better ductility performance after the peak load was reached, and their specific elastic strength and specific flexural strength were similar to those of honeycomb plates (HPs). In an EBEP before failure, the lower skin in the same location as the load was significantly stretched, and the trabeculae in the core showed two failure modes: destruction by means of slant cracks and vertical cracks. (2) The failure mechanism of the trabeculae in an EBEP was investigated by qualitatively analyzing the load and deformation of the parts adjacent and nonadjacent to the loading point. From the macro point of view, the cores of EBEP and HP are continuous. These cores can not only bear tension with lower skins, but also divide upper skins into much smaller parts and play a role as reinforcing ribs. The equivalent trabeculae in EBEP are closed ended, the honeycomb walls are narrow, and these two parts can support and constrain each other.