Biomimetic Study of a Honeycomb Energy Absorption Structure Based on Straw Micro-Porous Structure.

In this paper, sorghum and reed, which possess light stem structures in nature, were selected as biomimetic prototypes. Based on their mechanical stability characteristics-the porous structure at the node feature and the porous feature in the outer skin- biomimetic optimization design, simulation, and experimental research on both the traditional hexagonal structure and a hexagonal honeycomb structure were carried out. According to the two types of straw microcell and chamber structure characteristics, as well as the cellular energy absorption structure for the bionic optimization design, 22 honeycomb structures in 6 categories were considered, including a corrugated cell wall bionic design, a modular cell design, a reinforcement plate structure, and a self-similar structure, as well as a porous cell wall structure and gradient structures of variable wall thickness. Among them, HTPC-3 (a combined honeycomb structure), HSHT (a self-similar honeycomb structure), and HBCT-257 (a radial gradient variable wall thickness honeycomb structure) had the best performance: their energy absorption was 41.06%, 17.84%, and 83.59% higher than that of HHT (the traditional hexagonal honeycomb decoupling unit), respectively. Compared with HHT (a traditional hexagon honeycomb decoupling unit), the specific energy absorption was increased by 39.98%, 17.24%, and 26.61%, respectively. Verification test analysis revealed that the combined honeycomb structure performed the best and that its specific energy absorption was 22.82% higher than that of the traditional hexagonal structure.

Study on driver's active emergency response in dangerous traffic scenes based on driving simulator.

OBJECTIVE: A driver's active emergency response in dangerous traffic scenes consists of two parts, including reaction behavior and physiological state. In dangerous traffic scenes, the driver's active emergency response has an important impact on human collision injury. Clarifying the driver's active emergency response is an important prerequisite for the study of human collision injury under nonstandard posture. Therefore, this study investigates the driver's active emergency response in different inevitable collision scenes using driving simulator. METHODS: A driving simulator with a high-speed camera system and human physiological signal acquisition system was first built. Then, three typical vehicle dangerous collision scenes were developed, including frontal collision, side collision, and rear-end collision. Finally, twenty participants (15 males and 5 females) were recruited for a driving experiment, and their active emergency responses were recorded and analyzed. RESULTS: All subjects would rotate the steering wheel to the left or right in the active emergency state, and the rotation of the hand would also cause the subject's upper body to tilt in the same direction. The maximum angle for male subjects to rotate the steering wheel was 59.98°, while for the female subjects, it was 44.28°. In addition, the maximum grip force between the male subjects and the steering wheel was 280.5 N, compared to 192.5 N for female subjects. Compared to the female participants, the male participants not only have a greater rotation angle and a greater grip force on the steering wheel, but also have greater pressure on the brake pedal, and the foot moves quickly from the accelerator pedal to the brake pedal and presses the brake pedal. CONCLUSIONS: Drivers have different active emergency responses to different vehicle collision scenes. Quantitative statistics of driver's active emergency response will have important guiding significance for the analysis of the impact of human active emergency response on human injury characteristics in subsequent vehicle collision experiments.

Research on Impact Resistance of Aluminum Alloy New Rotating Thin-Walled Structures.

Honeycomb structures are widely used in the field of impact resistance and are constantly being developed and updated. In this paper, the design of three new aluminum alloy rotating thin-walled structures (NRTS) are examined. These structures combine common concave structures and rotating, rigid-body structures. The purpose of this study is to solve the problem of the poor energy absorption capacity of rotating, rigid-body structure due to small deformation and to provide a reference for honeycomb mechanism designs. The Young's modulus, the critical velocity, and the platform stress of the NRTS structure are derived from theoretical analysis. The dynamic response of the NRTS structure at different impact velocities is investigated using finite element simulation software. The results show that the rotating, thin-walled recessed honeycomb (RTRH) increases the plateau stress by 124% and 51% as compared to rotating, thin-walled square tubes (RTSTs) and the re-entrant hexagonal structure (RH), respectively; the rotating, thin-walled quadruple-arc honeycomb structure (RTQH) increases the SEA by 21% and 20% as compared to the RTST and RH, respectively; and the rotating thin-walled double-arc honeycomb structure (RTDH) increases the CEF by 54% and 51% as compared to the RTST and RH, respectively. During the study, it was demonstrated that NTRS also exhibits good energy absorption capacity. Then, the effect of rotation angle on the energy absorption performance was analyzed. The cell and wall thickness of the NTRS structure were optimized according to the gradient theory. It was proved that the gradient optimized structure has better energy absorption performance as compared to the uniform structure.

Analysis and clinical significance of peripheral blood routine changes of platelet donors with ultra-high frequency donation.

BACKGROUND: Increasing platelet donation frequency has become an important way to meet the growing clinical platelet need. Accordingly, the problem of whether the increase in platelet donation times will have an adverse effect on the health of donors has attracted more and more attention, and become an important factor affecting the donor enthusiasm and the safety of blood collection and supply. METHODS: Eleven ultra-high frequency platelet donors who donated more than or equal to 20 times in 2021 were selected, and the main peripheral blood routine indicators of hemoglobin, platelet and hematocrit were analyzed. RESULTS: The above indicators of all donors fluctuated with the increase of donation times. Among them, older donors (≥50 years old) exhibited a significant downward trend in the above three indicators, and one young donor showed a downward trend in hemoglobin and hematocrit indicators. While the other donors showed the relatively stable performance of the above indicators. CONCLUSION: The effect of ultra-high frequency platelet donation on the main peripheral blood indexes of donors shows obvious age compliance, that is, the potential harm to ultra-high frequency donors older than 50 years is significantly greater than that of donors of other ages. Older platelet donors should be cautious about ultra-high frequency donations to avoid adverse health hazards. Meanwhile, the work will provide technical reference for the more scientific and efficient development of the platelet harvesting work and the establishment of the clinical blood supply system for related patients.