To study the influence of structure size and composite forms on the mechanical properties of the composite double honeycomb sandwich structure, a composite double honeycomb sandwich structure was initially designed. The dynamic response of a composite double-layer honeycomb sandwich structure under high-speed impact was studied through theoretical analysis and numerical simulation. Ls-dyna software was used to simulate the initially designed composite structure. According to the numerical simulation results and the proposed method for calculating the fracture energy of the composite double honeycomb sandwich structure, the effects of different composite forms on the mechanical properties were analyzed. The results show that the proposed fracture energy calculation method can effectively describe the variation trend of the honeycomb structure and the micro-element fracture situation in the valid time. The fracture energy curve has a high sensitivity to cell density and material, and the strength of the top core has a great influence on the overall energy absorption. Compared with the traditional honeycomb protection structure, the energy absorption of the initially designed composite honeycomb sandwich structure was improved effectively.

In this work, the PEEK/short carbon fiber (CF) composites were prepared, a new thermodynamic coupling (preheating and impact compaction) process of the FDM method is proposed, and the warp deformation mechanism was obtained by finite element simulation analysis. Results show that a new method could improve the forming quality of an FDM sample. The porosity of FDM samples of the PEEK/CF composite gradually decreased from 10.15% to 6.83% with the increase in impact temperature and frequency. However, the interlayer bonding performance was reduced from 16.9 MPa to 8.50 MPa, which was attributed to the influence of the printing layer height change from the printhead to the forming layer. To explain the above phenomenon, a thermodynamic coupling model was established and a relevant mechanism was analyzed to better understand the interlayer mechanical and porosity properties of PEEK/CF composites. The study reported here provides a reference for improving the forming quality of fabricated PEEK/CF composites by FDM.

A micro-unmanned aerial vehicle (UAV) swarm has high flexibility and intelligent unmanned flight and stealth capabilities. Moreover, it can attack both single and group targets, which will occupy dominant positions in the future information war. To satisfy the new micro-UAV swarm information combat mode and contribute to the advances in ammunition flexibility, efficiency, miniaturization, and multipurpose applicability, a 10 mm caliber micro-shaped charge warhead was designed in this study. The results indicate that the micro-shaped charge can be assembled with a micro-UAV swarm to efficiently damage the targets without relying on the weapon launch velocity. To realize a lightweight and high-efficiency micro-shaped charge structure, the formability of Teflon, nylon, polycarbonate (polycarb), and metallic copper liners was studied using the finite element analysis. The penetration efficiencies of different micro-jets on gelatin targets were compared and analyzed. It was found that the micro-shaped charge nylon and Teflon jets could pass through the gelatin target and transfer more energy to it compared with copper. The observed penetration aperture was also larger. Although the penetration depth of the polycarb jet to the target was the smallest, the penetration aperture was the largest. The findings of this study can serve as a basis for the development of micro-shaped charge technology.