Abstract：The negative Poisson's ratio honeycomb structure has been widely used in the field of impact protection because of its unique mechanical properties and good energy absorption capacity. The evolution of local dynamic stress of negative Poisson's ratio honeycomb structure is closely related to the change of cellular microstructure under dynamic impact. The current research on negative Poisson's ratio structure mainly focuses on improving the energy absorption capacity of the whole structure by designing cells with concave deformation mechanism, ignoring structural optimization of existing models, and the research on other energy absorption mechanisms of rotary deformation is also lacking. In order to further improve the dynamic response of star-shaped honeycomb structures with negative Poisson's ratio under in-plane impact, the rotation characteristics of cells are studied in this paper. On the basis of the traditional star-shaped honeycomb structure, the structure of star-shaped honeycomb is further optimized, and the deformation energy absorption mechanism of star-shaped honeycomb cell is endowed with the coupling idea. Based on the principle of relative density equality, two kinds of rotating star-shaped cellular cells with double negative Poisson's ratio effect were obtained by internal rotation and external rotation: internal star-shaped cellular cells and external star-shaped cellular cells. The energy absorption characteristics of different honeycomb structures under in-plane impact loads were studied by numerical simulation, and the influence of both concave and rotating deformation mechanisms on the energy absorption characteristics of honeycomb structures was investigated. Based on one-dimensional shock wave theory and energy absorption efficiency method, the empirical formulas of dynamic platform stress and dense strain of star-shaped honeycomb are given, and the formulas for calculating relative density of star-shaped honeycomb structures are established. According to the theory of critical velocity, the first critical velocity and second critical velocity of star-shaped honeycomb structure are determined. The dynamic response of the rotating star-shaped honeycomb structure under different impact velocities is studied by explicit dynamic finite element method. The simulation results are compared and analyzed with the evaluation indexes of the model macro and micro deformation modes, platform stress and specific energy absorption. The results show that when the new structures are impacted, their cells first rotate and then recessed, which has a stronger negative Poisson's ratio effect. Under the impact of a medium speed of 20m/s, the platform stress of the internal honeycomb structure is higher and the stress stability of the platform is better. In the platform stage, the stress fluctuation of the external spiral honeycomb structure is more severe, but it has a higher specific absorption energy under the impact of high-speed 120m/s. The results of this paper show the relationship between the concave mechanism and rotation mechanism of star-shaped honeycomb structure and its energy absorption characteristics, which provides a new idea for the optimization of impact dynamic performance of honeycomb structure.
2025, Vol. 46 
