Flexural properties and failure mechanism of 3D-printed grid beetle elytron plates

Abstract

This paper studies the flexural mechanical behaviour of grid beetle elytron plates (GBEPs), which are lightweight and high-strength bionic structures with excellent compressive properties, for the first time. The flexural properties, failure modes and flexural mechanism of 3D-printed GBEP, grid plate (GP) and honeycomb plate (HP) specimens with the same wall thickness are investigated via three-point bending experiments. The results show that the flexural strength per unit mass and energy absorption per unit mass of the GP and GBEP are greatly improved and that the stress per unit mass corresponding to elastic stage I in the serviceability state is improved over those of typical lightweight and high-strength HPs. The fracture location and range of the GBEP are affected by the diameter of the trabecula. The experimental results indicate that the grid group effectively solves the problem of insufficient core shear strength in HPs through the regular grid core structure, which successfully converts core failure in shear of the HP to face failure in tension of the GBEP and GP. The flexural mechanisms of the three types of plates are revealed from multiple perspectives, such as the relationship between the facing stress and core shear stress and the tension field effect induced by the film force. This work provides useful instruction for designing lightweight sandwich structures, further develops the application of beetle elytron plates used in many fields such as aircraft bodies and ship floor, and presents a scientific basis for rational selection among GPs, GBEPs and HPs in practical engineering.