| With the development of information technology,the future war mainly erupts in the local war of weapon equipment system dominated by information technology.Individual soldiers,especially infantry,are regarded as'Queen of the Battlefield'and the protagonist of the future war.As the fundamental component of individual combat system,personal protective equipment can significantly reduce the casualty rate of individual soldiers,the damage of high-speed fragments,light weapons projectiles and other killing elements to human body,and protect the life safety of soldiers as well.Practice shows that the casualty rate increases with the modernization of weapon equipment.With the popularization of modern single-armed grenade weapons,the wide application of light weapons fire control system and air explosion grenade,deep penetration and strong impact have become the main problems that need to be solved urgently in the development of personal protective equipment in various countries.At present,researchers mainly improve the performance of protective equipment from the aspects of bulletproof material modification and multi-material laminated combination.However,these methods have failed to meet the needs of the protection ability improvement and lightweight development of protective equipment,and therefore have been stuck in a deadlock.Inspired by bionics,this paper uses the basic concepts and methods of bionics and select Leiurus quinquestriatus,a typical desert scorpion,as a bionic prototype to reveal the realization mechanism of the excellent anti-impact protection function of the terga of the desert scorpion.Based on this mechanism,the surface model of bionic convex hull form was established by using the similarity principle.The role of bionic convex hull form in the process of bullet resistance was explored by combining numerical simulation and experimental analysis,and the mechanism of excellent bullet resistance of bionic surface was revealed.details are as follows:Firstly,the macroscopic/microscopic morphology and cross-sectional morphology of the body surface of the Palestinian scorpion terga were characterized and analyzed.It was found that the transverse curvature of the Israeli gold scorpion terga increased gradually from the middle to both sides,and the body surface distribution had a distinct convex hull form.The convex hull form on both sides was trapezoidal distribution,and the convex hull in the middle was scattered around the middle axis,which was smaller than the convex hull particle size on the axis and on both sides.Meanwhile,the shape surface of the convex hull was composed of different arc layers.The upper space of the convex hull was distributed with small convex hull and linear convex shape.The surface of the gap between the convex hull was covered with quadrilateral and hexagonal pits.It could be concluded that the curvature change of dorsal plate and the regional distribution of convex hull of scorpion was related to its living environment and physiological stress response,which was an optimized protection mechanism for its protection of its own stress response evolution.The cross section of the terga consisted of five layers of different structural layers:the dense upper epidermis,the inner and outer cuticles of the outer epidermis,the middle spiral layer of the inner epidermis and the inner layer of the plate-like fiber.The middle spiral layer was the thickest,accounting for more than half of the total thickness,and its layers accounted for a small proportion.There were a large number of transverse and longitudinal channel structures between each layer:transverse channels are mostly distributed between the fiber bundles of the middle spiral layer,which increased the compliance of this layer;the longitudinal channel ran through the inner horny layer and the middle layer,and the fiber bundles in the hole connected the two layers closely.There were many small longitudinal channels in the inner horny layer,which improved the multi-channel path for the self-healing of the terga surface and the transportation of nutrients and ions.Then,the composition,impact resistance and interlaminar mechanical properties gradient distribution of the Israeli golded scorpion terga were studied.It was found that the Israeli golden scorpion terga was mainly composed of chitin and protein,which was a functional gradient material.The content of metal elements in the side of the terga was higher than that in the middle of the backboard.The content of metal elements in the outer epidermis and the middle spiral layer of the backboard was much higher than that in the other layers.The mechanical properties of the side of the backboard were better than those of the middle of the backboard.The mechanical properties of the outer epidermis and the middle spiral layer of each layer were also the best.At the same time,the mechanical properties of the side of the terga were better than those of the middle of the backboard,indicating that trace metal elements could indeed effectively enhance the mechanical properties of the material.Taking Heterometrus petersii as the control group,the qualitative and quantitative characterization test of the directional impact resistance of the Israeli golden scorpion terga showed that the Israeli gold scorpion terga had better impact resistance.compared with the large area brittle fracture failure of the rainforest scorpion terga,the failure mode of the terga,was the plastic crack failure with regular extension,which could resist the sand impact under greater pressure,and the impact strength was about 6.01 KJ/m~2.Subsequently,the anti-attack mechanism of multi-factors such as the curvature of the terga,body surface morphology and gradient layered structure of the Israeli scorpion was analyzed.Based on the characteristic parameters of the shape,structure and material of the Israeli golden scorpion terga,a model of anti-shock and anti-bombing was established.After that,the simulation software was adopted to explore the protection mechanism of a single convex hull form,and it was found that the ballistic protection performance of the model with a single bionic surface shape was better than that of the plate model with the same volume.Under the same impact conditions,the protection performance level of the bionic model with 7.5 mm thickness was the same as that of the plate model with 10 mm thickness,but the weight of the bionic model at this time was significantly lower than that of the plate model,which was about 15%lighter.Finally,the design,manufacture and protection performance test of the bionic surface specimen with multi-convex hull form and the equal volume plate specimen were carried out.It was found that the damage forms of the two specimens were similar.The damage and fragmentation area of the ceramic panel of the bionic specimen was larger than that of the plate specimen,and the damage degree of the floor was smaller than that of the floor of the plate specimen.Under the same velocity,when the impact point as located in the center area,the damage grade of the bionic sample back plate was less than that of the flat sample,and the back convex value is about 28.8%lower than that of the flat sample.When located in the eccentric area,the backplane damage grades of the two samples are the same,and the back convex value was about 24.9%smaller than that of the flat sample.Combined with the theoretical analysis,the anti-elastic mechanism of bionic convex hull form was further revealed.It was found that the bionic convex hull form had two special anti-elastic effects:the warhead deflection effect and the stress concentration and slow release effect.Increasing the damaged area and fragmentation of the ceramic panel,the stress was dissipated in a wide range,the penetration energy and depth of the center of the impact point were consequently reduced,and the back convex value of the bottom plate was greatly reduced. |
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