## 1 Introduction  
The concept of the honeycomb sandwich structure has attracted wide attention. After decades of development, the honeycomb structure has made breakthroughs in structural design, damage resistance and material application. The unique advantages of sandwich structure are their improved energy absorption capacity and excellent impact resistance. These advantages of the sandwich structure make it widely used in engineering applications, such as the ship, automobile, aviation and aviation industries [1]. It can be seen that the superiority of the honeycomb structure is becoming more and more prominent. Since [PERSON] et al. [2] proposed the use of a honeycomb structure in a sandwich structure in 1915, this sandwich structure has been widely used in the fuselage. At present,the common honeycomb structures are mainly circular, quadrilateral, hexagonal, corrugated, foam, negative Poisson's ratio [3; 4; 5; 6; 7; 8], the zero Poisson's ratio, chiral and anti-chiral structures that have emerged in recent years [9; 10; 11; 12]. In many cell studies, triangles, squares, circles and hexagons are the most widely used. A hexagonal honeycomb structure can obtain the maximum force with the least material. When it is subjected to out-of-plane load, its bending stiffness is almost the same as that of the same material and the same thickness plate structure, and both the structural stiffness impact resistance and energy absorption capacity are higher than other cell structures. With different combinations, there are honeycomb sandwich structures of the structural composite type, step type and mixed type of different materials [13; 14; 15]. At present, the application in aerospace is mainly based on the hexagonal honeycomb core that imitates the honeycomb. In military protection and explosion protection, the negative Poisson's ratio and chiral structure are widely used. The most widely used is still the explosion-proof wall. The rest of the structure is still in the research stage, and it takes a long time to be widely used. The effectiveness of honeycomb sandwich structures is generally related to the physical properties of the structure, such as cell size, core thickness and arrangement, which affect the strength, stiffness and overall performance of the sandwich structure. The experimental results confirm that the Poisson's ratio, elastic modulus and compressive properties of honeycombs are indeed related to topological characteristics [16]. In recent years, the research on the design of a honeycomb core structure is in full swing, and the type of honeycomb cell has also been greatly improved on the basis of the traditional single configuration. The emergence of multi-level honeycomb provides the possibility for the structure to improve the impact resistance. Compared with the traditional honeycomb aluminum sandwich plate, the multi-level honeycomb aluminum sandwich plate has a small deflection on the back plate surface and good impact resistance under large load, and this advantage becomes more and more obvious with the gradual increase in load [17]. [PERSON], [PERSON] et al. [18] found that based on the NOMEX honeycomb core, the skin is made of a multi-layer composite material, which is bonded by a high-strength adhesive film. The impact test of the structure was carried out by using the drop hammer test machine. Compared with the study of [PERSON] et al. [19], the impact energy is relatively low, and the main energy dissipation of the structure is still dominated by the fiber tensile fracture of the composite skin. [PERSON], [PERSON] et al. [20] compared the tube-reinforced honeycomb sandwich structure with the traditional honeycomb structure and found that the filling of the metal tube improved the stiffness and peak load of the traditional honeycomb structure, making the stress and deformation of the front and rear skins more uniform. The energy absorption characteristics of the structure are faster than that of the empty honeycomb structure, and the deformation of the front skin is reduced.