The Characteristic Study Of The Novel Honeycomb Materials Under The In-plane Dynamic Impact

Due to high strength,excellent heat resistance,excellent impact resistance and flexible performance controllability,lightweight honeycomb materials are widely used in various high-tech fields such as aerospace,civil engineering,mechanical engineering and medical supplies.With the increasing industrialization of society,the optimization of traditional honeycomb under the in-plane dynamic crushing and the theoretical analysis of the mechanical properties of the novel honeycomb have become the current research hotspots.In this paper,we propose three options for optimizing the performance of traditional honeycomb.In the meanwhile,the mechanical properties of the novel honeycomb is theoretically analyzed.Subsequently,we adopt the finite element simulation,the theoretical analysis to reveal the correlation between the mechanical properties of the new honeycomb and the topological microstructure of the cell under in-plane dynamic impact.The effects of geometry,temperature field,relative density and impact velocity on the deformation mode and energy absorption performance of honeycomb are summarized.(1)Due to the unstable structural characteristics of square cell elements,square honeycombs undergo slip deformation to the sides when the honeycomb is impacted at middle and low velocities,and consequently,the energy absorption capacities are low.To improve the energy absorption and modify the dynamic crushing behavior of the square honeycomb,a novel square honeycomb was proposed in which rods are added to the interior of the square cell elements.Subsequently,two graded gradient honeycombs and a“buffer” honeycomb were established based on the novel square unit cell,and their energy absorption properties were investigated.It was demonstrated that one of the gradient square honeycombs exhibited the best specific energy absorption under low-velocity crushing,and the buffered square honeycomb showed the best crushing force efficiency for a mid-velocity collision.Furthermore,the slip degree of the honeycomb deformation mode was strongly inhibited for one of the novel square honeycombs,which exhibited the zero Poisson’s ratio effect.In addition,the deformation mechanism of the novel square honeycomb under low-and mid-impact velocity is theoretical analyzed.The causes of the double-plateau phenomenon in the novel buffer honeycomb is presented.(2)To enhance the mechanical performances of traditional honeycombs,a novel combined honeycomb(HKH)was proposed based on the regular hexagonal honeycomb(RHH)and Kagome honeycomb(KH).A systematic investigation of the in-plane dynamic crushing behaviors of the honeycombs was conducted via the finite element method,and the crashworthiness characteristics of the three honeycombs were examined.Using onedimensional shock wave theory and least squares fitting,a fitting formula of the plateau stress was obtained,the relative density is also used to deeply explore the performance improvement of the new combined honeycomb for RHH.The results showed that the HKH exhibited a higher plateau stress than the RHH for any velocity impact,while the negative Poisson’s ratio effect was more significant than that of the KH for low-velocity impacts.Furthermore,the effects of the impact velocity and relative density on the energy absorption and auxetic performances were explored.(3)By deforming two cell walls of a triangular honeycomb(TH)inward to various degrees,novel re-entrant triangular honeycombs(RTs)were designed.Two novel RT structures were considered—a regular RT(RRT)and a staggered RT(SRT)—to conduct a systematic investigation.The results show that the RTs had rich deformation modes under different impact velocities,in which the RRT exhibited a double-plateau stage and the SRT possessed a large negative Poisson’s ratio.Subsequently,the deformation mechanisms of the RTs were explained.The theoretical formula of the plateau stress was deduced according to the energy conservation and momentum theorem under low-and mid-velocity impact.As the same relative density,the RT exhibited a higher energy-absorbing capacity and crashworthiness for mid-velocity crushing,and this trend was amplified by the impact velocity.Finally,the reason for the best RRT performance when the top angle is a right angle is revealed.Finally,the inner concave design substantially reduces the initial peak stress of the honeycomb,and the adjustment of the topological microstructure have no effect on the deterioration of the metal honeycomb crashworthiness due to the increase in external temperature.Figure [53] table [11] reference [102]...