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.

本文首次研究了网格甲虫鞘翅片（GBEPs）的弯曲力学行为，GBEPs 是一种轻质、高强度、具有优异压缩性能的仿生结构。通过三点弯曲实验研究了具有相同壁厚的 3D 打印 GBEP、网格板 (GP) 和蜂窝板 (HP) 试样的弯曲性能、破坏模式和弯曲机制。结果表明，GP和GBEP的单位质量抗弯强度和单位质量能量吸收有很大提高，在使用状态下对应弹性阶段I的单位质量应力比典型的轻量化和高力量HP。GBEP 的骨折位置和范围受小梁直径的影响。实验结果表明，网格组通过规则的网格核心结构，有效解决了HPs核心抗剪强度不足的问题，成功地将HP的核心剪切破坏转化为GBEP和GP的拉力面破坏。从面应力与芯部剪应力的关系、薄膜力引起的张力场效应等多个角度揭示了三种板材的弯曲机理。该工作为轻型夹层结构的设计提供了有益的指导，进一步发展了甲虫鞘翅在飞机机身、船底板等领域的应用，为实际工程中GPs、GBEPs和HPs的合理选择提供了科学依据。