A protective device and its preparation method and application

Abstract

The present invention provides a protective device and a preparation method and application thereof, which relate to the field of bulletproof technology. The protective device includes a negative Poisson's ratio structural plate, which is located inside an ultra-high performance concrete, and the cavity inside the negative Poisson's ratio structural plate and the periphery of the negative Poisson's ratio structural plate are filled with ultra-high performance concrete; the negative Poisson's ratio structural plate includes a double-arrow structural layer and a sinusoidal structural layer arranged in sequence in a direction perpendicular to the bullet-facing surface, the cross-section of the double-arrow structural layer is a double-arrow-shaped negative Poisson's ratio structure, and the cross-section of the sinusoidal structural layer is a sinusoidal negative Poisson's ratio structure; the sharp angle direction in the double-arrow structural layer is perpendicular to the bullet-facing surface, and the wave crest of the sinusoidal structural layer is connected to the end of the sharp angle structure. The negative Poisson's ratio structure can absorb and disperse impact energy through geometric deformation, and the sharp angle structural design can effectively deflect the trajectory of the bullet, and can improve the energy absorption capacity of the ultra-high performance concrete, thereby reducing its penetration depth.

Description

Technical Field

[0001] The present invention relates to the field of bulletproof technology, and in particular to a protective device and a preparation method and application thereof. Background Art

[0002] In the design of protective buildings and other important structures, penetration resistance has become a key performance indicator. Although conventional ordinary concrete can resist damage caused by extreme loads to a certain extent, its energy absorption capacity is limited. Especially in the face of high-energy impacts such as explosion fragments and bullet penetration, it is usually necessary to increase the thickness of concrete to provide adequate protection. However, this method of increasing thickness not only leads to increased material costs, but also brings many restrictions to the design and construction of buildings.

[0003] Conventional ordinary concrete is usually toughened with steel bars or steel fibers to improve the penetration resistance of protective structures. Although this method enhances the strength and toughness of concrete, its energy absorption capacity is still insufficient when facing extreme loads such as explosion impact. When high-speed bullets or fragments hit concrete, the residual velocity of the bullet is too high and continues to pose a threat to targets behind. In addition, when concrete is penetrated, it is often accompanied by a large amount of fragments splashing or collapsing. These fragments themselves can also cause additional damage, especially in crowded areas, which increases safety risks.

[0004] In addition, the traditional reinforced concrete design mainly considers the tensile strength under static load and long-term use, while the energy absorption capacity and deformation capacity under dynamic impact are relatively limited. This makes the structure prone to local failure or damage when facing dynamic impacts such as explosions or high-speed collisions. Therefore, it is necessary to study how to further improve the anti-penetration performance of concrete to effectively absorb and disperse impact energy, so as to meet the increasing safety needs of modern military and civilian protection facilities. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a protective device and a preparation method and application thereof, and to introduce a negative Poisson's ratio structure into ultra-high performance concrete, which not only improves the energy absorption capacity of the ultra-high performance concrete, but also utilizes the two-arm design of the pointed structure to effectively deflect the trajectory of the bullet, thereby reducing its penetration depth.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] A first aspect of the present invention provides a protective device, comprising a negative Poisson's ratio structural plate, wherein the negative Poisson's ratio structural plate is located inside an ultra-high performance concrete, and the cavity of the negative Poisson's ratio structural plate is filled with the ultra-high performance concrete; the negative Poisson's ratio structural plate comprises a double-arrow structural layer and a sinusoidal structural layer arranged in sequence along a direction perpendicular to a bullet-facing surface, the cross-section of the double-arrow structural layer is a double-arrow-shaped negative Poisson's ratio structure, and the cross-section of the sinusoidal structural layer is a sinusoidal negative Poisson's ratio structure; the direction of the sharp angle in the double-arrow structural layer is perpendicular to the bullet-facing surface, the wave crest of the sinusoidal structural layer is connected to the end of the sharp angle structure, and the sinusoidal structural layer is located on the side of the double-arrow structural layer away from the bullet-facing surface.

[0008] Optionally, the negative Poisson's ratio structural plate includes at least one layer of sheets, each layer of sheets includes a plurality of micro cells connected to each other; the cross-sectional structure of the micro cells includes a frame surrounded by a first beam, a second beam and a bottom beam, the head ends of the first beam and the second beam are connected, and the tail ends of the first beam and the second beam are respectively opened to form a pointed structure; the two ends of the curved bottom beam are respectively connected to the tail ends of the first beam and the second beam; inside the frame, a pointed cross beam is connected between the first beam and the second beam, and the pointed cross beam has the same direction as the pointed structure, and outside the frame, the first beam and the second beam extend out a first side beam and a second side beam obliquely toward the tail end, respectively; between adjacent micro cells, the first side beam is connected to the second side beam, and the tail end of the first beam is connected to the tail end of the second beam.

[0009] Optionally, the ultra-high performance concrete is composed of the following components in parts by weight: 360-520 parts of cement, 36-52 parts of silica fume, 36-52 parts of fly ash, 800-1000 parts of fine aggregate, 800-1000 parts of coarse aggregate, 39-78 parts of steel fiber, 120-130 parts of water and 5-10 parts of high-efficiency water reducing agent.

[0010] In a second aspect, a method for preparing the above-mentioned protective device comprises the following steps:

[0011] S1. preparing a negative Poisson's ratio structural plate, and placing the negative Poisson's ratio structural plate in a casting mold;

[0012] S2. mixing to obtain a mixture of ultra-high performance concrete;

[0013] S3. Pour the mixture into a mould so that the mixture fills the cavity in the negative Poisson's ratio structural plate and the gap between the negative Poisson's ratio structural plate and the pouring mould, and perform curing to obtain a protective device.

[0014] Optionally, in S1, a negative Poisson's ratio structural plate is prepared by 3D printing or injection molding.

[0015] The beneficial effects of the present invention are:

[0016] 1. The present invention introduces a negative Poisson's ratio structure into ultra-high performance concrete, which greatly improves the material's anti-penetration ability: the negative Poisson's ratio structure can absorb and disperse impact energy through geometric deformation, and the pointed structural design can effectively deflect the trajectory of the bullet, forming a wider stress distribution area around the impact point, which can effectively reduce local damage. After being compounded with ultra-high performance concrete, it can improve the energy absorption capacity of ultra-high performance concrete, thereby reducing its penetration depth.

[0017] 2. In the negative Poisson's ratio structure of the present invention, the geometric deformation process of the pointed angle structure and the sinusoidal bottom beam structure can absorb and disperse the impact energy, effectively improving the energy absorption capacity of the overall structure, and the dispersed shrapnel is further blocked by the fiber interlaced structure and aggregate in the ultra-high strength concrete. This design enables the ultra-high performance concrete slab to provide excellent protection even in a thinner case, reducing the risk of shrapnel penetrating the concrete layer.

[0018] 3. The present invention achieves a perfect combination of light weight and high durability through geometric design optimization and material innovation, combined with modern manufacturing technology and high-performance material science. The efficient design of the negative Poisson's ratio structure allows the weight of the material to be reduced without sacrificing strength, which not only reduces the overall burden of the building, but also reduces transportation and construction costs. In addition, the excellent durability of ultra-high performance concrete enables the material to maintain good performance even in harsh environments, extending the service life of buildings and facilities. It is very suitable for high-safety building designs with strict requirements on structural weight, and is not only suitable for the construction of new facilities, but also provides an ideal choice for upgrading and renovating existing structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0020] Figure 1 It is a schematic diagram of the cross-sectional structure of the microcell in Example 1.

[0021] Figure 2 Schematic diagram of the connection structure of adjacent micro cells in Example 1.

[0022] Figure 3 Schematic diagram of the structure of the negative Poisson's ratio structural plate in Example 1.

[0023] Figure 4 It is a flow chart of the preparation method in Example 1.

[0024] Figure 4 Schematic diagram of the test device in Experimental Example 1.

[0025] Among them, 1. the first beam; 2. the second beam; 3. the first side beam; 4. the second side beam; 5. the pointed cross beam; 6. the curved bottom beam. DETAILED DESCRIPTION

[0026] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0027] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0028] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0029] A protective device comprises a negative Poisson's ratio structural plate, wherein the cavity inside the negative Poisson's ratio structural plate and the periphery of the negative Poisson's ratio structural plate are filled with ultra-high performance concrete; the negative Poisson's ratio structural plate comprises a double-arrow structural layer and a sinusoidal structural layer arranged in sequence along a direction perpendicular to a projectile-facing surface, the cross-section of the double-arrow structural layer is a double-arrow-shaped negative Poisson's ratio structure, and the cross-section of the sinusoidal structural layer is a sinusoidal negative Poisson's ratio structure; the sharp angle direction in the double-arrow structural layer is perpendicular to the projectile-facing surface, the wave crest of the sinusoidal structural layer is connected to the end of the sharp angle structure, and the sinusoidal structural layer is located on the side of the double-arrow structural layer away from the projectile-facing surface.

[0030] In the above device, the pointed structure in the double-arrow structural layer has the function of deflecting the movement direction of the shrapnel. The sinusoidal curve includes a first sinusoidal curve segment and a second sinusoidal curve segment symmetrically arranged. The first sinusoidal curve segment and the second sinusoidal curve segment are connected at an outward convex position to form a wave shape. The wave crest is connected to the top of the pointed angle facing away from the bullet-facing surface, and the wave trough can be connected to the top of the pointed angle facing the bullet-facing surface, thereby realizing a combined connection of the sinusoidal Poisson's ratio structure and the double-arrow Poisson's ratio structure in the thickness direction of the device; the double-arrow structure has a large number of inclined surfaces, which is more advantageous in deflecting the trajectory of bullets. The smooth curved surface contour of the sinusoidal Poisson's ratio structure is conducive to close integration with the ultra-high performance concrete inside, thereby improving the energy absorption effect of this part; the negative Poisson's ratio structure can absorb impact energy through its own deformation, and combined with the excellent mechanical properties of the ultra-high performance concrete itself, it can effectively improve the protection capability.

[0031] Optionally, the negative Poisson's ratio structural plate includes at least one layer of sheets, each layer of sheets includes a plurality of micro cells connected to each other, the negative Poisson's ratio structural plate is a whole formed by periodically arranging a plurality of micro cells, each micro cell is connected to adjacent micro cells, the deformation of a single micro cell can cause the coordinated deformation of adjacent micro cells, and jointly share the impact; the cross-sectional structure of the micro cell includes a frame surrounded by a first beam, a second beam and a bottom beam, the head ends of the first beam and the second beam are connected, and the tail ends are respectively opened to form a pointed angle structure; the two ends of the curved bottom beam are respectively connected to the tail ends of the first beam and the second beam, and the middle position bulges outward in a direction away from the head end, the first beam, the second beam and the bottom beam constitute the basic structure of the micro cell, the pointed angle structure composed of the first beam and the second beam can deflect the movement trajectory of the bullet, and the curved bottom beam at the rear can effectively absorb the impact energy of the bullet, and the deformation trend of the negative Poisson's ratio structure when subjected to external force is contraction, which is similar to the crushing and dispersion of ultra-high performance concrete when subjected to impact. The deformation trends are opposite, and the two can work together to effectively improve the anti-penetration performance of concrete; inside the frame, a pointed cross beam is connected between the first beam and the second beam, and the pointed cross beam has the same direction as the pointed structure, and outside the frame, the first beam and the second beam extend the first side beam and the second side beam obliquely toward the tail end, respectively, and the pointed cross beam, the first side beam and the second side beam function to form a double-arrow-shaped negative Poisson's ratio structure, which can increase the number of pointed structures in the negative Poisson's ratio structural plate and improve the deflection effect on bullets; between adjacent micro cells, the first side beam is connected to the second side beam, and the tail end of the first beam is connected to the tail end of the second beam, therefore, the connection form of adjacent micro cells is basically point connection, so that the thin-walled structure in the negative Poisson's ratio structural plate is dispersed as evenly as possible inside the protective device, the contact area between the negative Poisson's ratio structural plate and the ultra-high performance concrete is increased, and the energy absorption effect of the interface of dissimilar materials in the device is increased.

[0032] In the above structure, the negative Poisson's ratio structural plate is composed of a double-arrow-shaped negative Poisson's ratio structure and a curved structure: the triangular slope of the double-arrow shape (i.e. the two arms of the pointed structure in the cross section) can effectively deflect the movement trajectory of the bullet, thereby reducing its penetration depth. Both the double-arrow and curved structures are negative Poisson's ratio structures, which have the function of absorbing and dispersing impact energy through geometric deformation when subjected to high-speed impact. Combined with the energy absorption capacity of ultra-high performance concrete itself, it can provide higher safety guarantees in military and civilian buildings, and also has the characteristics of lightweight.

[0033] Optionally, the frame in the microcell is composed of materials of substantially equal thickness, and the wall thickness of the frame in the microcell is 5 to 15 mm, which is easy to manufacture, and its regularly shaped cavity is conducive to filling the dense ultra-high performance concrete inside, reducing defects such as internal cavities or bubbles. At the same time, since the ultra-high performance concrete in the cavity of the microcell is relatively independent of each other during the solidification process, it can effectively avoid the generation of cracks during the curing process, further improving the overall mechanical properties of the material.

[0034] Optionally, the microcell is bilaterally symmetrical with the angle bisector of the pointed structure as the axis of symmetry, so that a plurality of microcells are combined into a structural layer with uniform performance.

[0035] Optionally, on the first beam, the extending position of the cross beam is located between the extending position of the first side beam and the tail end, and on the second beam, the extending position of the cross beam is located between the extending position of the second side beam and the tail end; the pointed cross beam is formed by connecting two sections of straight line sections extending from the first beam and the second beam respectively; the two ends of the pointed cross beam are respectively connected to the trisection points of the first beam and the second beam near the head end; the first side beam and the second side beam are respectively connected to the trisection points of the first beam and the second beam near the tail end; The first side beam is parallel to the straight section of the extended pointed cross beam, and the second side beam extended from the second beam is parallel to the straight section of the extended pointed cross beam; the double-arrow-shaped negative Poisson's ratio structure formed by the two has not only an energy-absorbing effect, but also the inclined surface of the pointed structure can effectively deflect the movement trajectory of the shrapnel. Since the pointed structure faces the projectile surface, it can effectively reduce the velocity component of the shrapnel perpendicular to the projectile surface, thereby assuming the impact energy of the bullet in a larger range, driving the negative Poisson's ratio structures at other positions to deform cooperatively, and at the same time dispersing the impact energy in a larger range of ultra-high performance concrete fillers.

[0036] Optionally, between adjacent layers, the head ends of the first beam and the second beam are connected to the convex position of the bottom beam, so that the adjacent layers are combined and connected to form a multi-layer negative Poisson's ratio structure.

[0037] Optionally, the ultra-high performance concrete is composed of the following components in parts by weight: 360-520 parts of cement, 36-52 parts of silica fume, 36-52 parts of fly ash, 800-1000 parts of fine aggregate, 800-1000 parts of coarse aggregate, 39-78 parts of steel fiber, 120-130 parts of water and 5-10 parts of high-efficiency water reducing agent; coarse aggregate is added to the selected ultra-high performance concrete, and the coarse aggregate itself has high strength and can resist impact; the interface between the coarse aggregate and the concrete matrix also has an energy absorption effect, which is beneficial to improving the impact resistance of the material.

[0038] Optionally, the material of the coarse aggregate includes one or more of basalt, sintered bauxite and corundum, and the particle size is 5-8 mm. The particle size needs to match the cavity size of the negative Poisson's ratio structural plate so that the coarse aggregate can be evenly distributed in the protective device.

[0039] The method for preparing the protective device comprises the following steps:

[0040] S1. preparing a negative Poisson's ratio structural plate, and placing the negative Poisson's ratio structural plate in a casting mold;

[0041] S2. mixing to obtain a uniform mixture of ultra-high performance concrete;

[0042] S3. Pour the mixture into a mould so that the mixture fills the cavity in the negative Poisson's ratio structural plate and the gap between the negative Poisson's ratio structural plate and the pouring mould, and perform curing to obtain a protective device.

[0043] Through the above process, the ultra-high performance concrete formed by the mixture is poured into the inside and outside of the negative Poisson's ratio structural plate, forming a composite material with the negative Poisson's ratio structural plate as the internal skeleton. It can simultaneously give play to the performance and structural advantages of both materials, and provide an efficient solution for dealing with high penetration threats by reducing structural weight and improving durability.

[0044] Optionally, in S1, a negative Poisson's ratio structural plate is prepared by 3D printing or injection molding; 3D printing includes wire 3D printing and powder 3D printing, which can be used for nylon or metal materials; injection molding can be used for nylon materials. Since the shape of the negative Poisson's ratio structure is relatively complex, it is necessary to select a preparation process that can adapt to the molding of complex shapes.

[0045] Optionally, in S2, cement, fly ash, silica fume, fine aggregate and coarse aggregate are dry-mixed, then water and water reducing agent are added and stirred, and then steel fiber is added and stirred to obtain a uniform mixture; after adding the steel fiber, the stirring speed is 100~130r / min, and the stirring time is 2.5~4min; in S3, before pouring, the mixture is stirred at a stirring speed of 140~160r / min, and the stirring time is 2~3min; this addition order is a common preparation method for ultra-high performance concrete, and the stirring time and stirring speed can be flexibly adjusted by technical personnel.

[0046] Optionally, in S3, air bubbles in the concrete are removed after pouring, especially air bubbles at sharp corners are eliminated by vibration to improve the compactness of the protective device.

[0047] Optionally, in S3, surface treatment and size adjustment are performed after curing, including grinding and cutting, to obtain a protective device that meets the size specification requirements.

[0048] The above protection device is used in protection facilities. In the negative Poisson's ratio structural plate, the sharp-angle structure faces the bullet-facing surface, so that the sharp-angle structure contacts the bullet first, which can effectively deflect the trajectory of the bullet and form a wider stress distribution area around the impact point.

[0049] Example 1

[0050] A protective device comprises a negative Poisson's ratio structural plate, wherein the cavity inside the negative Poisson's ratio structural plate and the periphery of the negative Poisson's ratio structural plate are filled with ultra-high performance concrete; the thickness of the protective device is 150 mm, and the dimension of the internal negative Poisson's ratio structural plate in the thickness direction is 140 mm.

[0051] The negative Poisson's ratio structural plate includes two layers, each layer includes a plurality of micro cells connected to each other; Figure 1 As shown, the cross-sectional structure of the microcell includes a frame surrounded by a first beam 1, a second beam 2 and a curved bottom beam 6, wherein the head ends of the first beam 1 and the second beam 2 are connected, and the tail ends are opened to form a pointed structure; the two ends of the curved bottom beam 6 are respectively connected to the tail ends of the first beam 1 and the second beam 2, and the middle position bulges outward in a direction away from the head end; inside the frame, a pointed cross beam 5 is connected between the first beam 1 and the second beam 2, and the pointed cross beam 5 is in the same direction as the pointed structure; outside the frame, the first beam 1 and the second beam 2 extend outwardly from the first side beam 3 and the second side beam 4 obliquely toward the tail end, respectively.

[0052] like Figure 2 As shown, between adjacent micro cells, the first side beam 3 is connected to the second side beam 4, and the tail end of the first beam 1 is connected to the tail end of the second beam 2; between adjacent layers, the head ends of the first beam 1 and the second beam 2 are connected to the convex position of the curved bottom beam 6.

[0053] like Figure 1 As shown, the shape of the curved bottom beam 6 is a sine curve, including a first sine curve segment and a second sine curve segment symmetrically arranged, and the first sine curve segment and the second sine curve segment are connected at a convex position; the pointed cross beam 5 is formed by connecting straight segments extending from the first beam 1 and the second beam 2 respectively, the first side beam 3 extending from the first beam 1 and the straight segment of the extended pointed cross beam 5 are parallel, and the second side beam 4 extending from the second beam 2 and the straight segment of the extended pointed cross beam 5 are parallel; the two ends of the pointed cross beam 5 are respectively connected to the trisection points of the first beam 1 and the second beam 2 near the head end; the first side beam 3 and the second side beam 4 are respectively connected to the trisection points of the first beam 1 and the second beam 2 near the tail end; with the angle bisector of the pointed structure as the symmetry axis, the microcell is bilaterally symmetrical.

[0054] The local part of the prepared negative Poisson's ratio structural plate is as follows Figure 3 As shown, the surface toward which the sharp angle formed by the head ends of the first beam 1 and the second beam 2 faces is the bullet-facing surface.

[0055] The material of the negative Poisson's ratio structural plate is reinforced nylon, which has high strength and toughness. The tensile strength of reinforced nylon is 100MPa, the elongation at break is 4%, the density is 1.18g / cm³, and the impact resistance is excellent. In the negative Poisson's ratio structural plate, the dimension of the frame material in the thickness direction is 140mm, and the thickness of the frame wall in the microcell is 10mm.

[0056] The ultra-high performance concrete is composed of the following components in parts by weight: 400 parts of cement, 40 parts of silica fume, 40 parts of fly ash, 900 parts of river sand, 900 parts of basalt coarse aggregate, 39 parts of steel fiber, 120 parts of water, and 8 parts of water reducing agent.

[0057] The cement is 52.5 grade ordinary Portland cement.

[0058] The silica mass percentage of silica fume is not less than 97%, the volcanic ash activity index is greater than 95%, the specific surface area is greater than 21.0m² / g, and the density is 2.20g / cm³.

[0059] The fly ash is Class I fly ash, with a loss on ignition of less than 3.0%, a specific surface area of ​​more than 1000cm² / g, and mainly contains silicon oxide and aluminum oxide.

[0060] Natural river sand is fine aggregate with a fineness modulus of 2.3 and a maximum particle size of 4.75 mm.

[0061] Basalt coarse aggregate is coarse aggregate with a particle size of 5~8mm.

[0062] The steel fiber is a straight steel fiber with a length of 13 mm.

[0063] The high-efficiency water reducer is polycarboxylic acid water reducer with a water reduction rate of >30%.

[0064] The preparation method comprises the following steps.

[0065] S1. Use reinforced nylon material to 3D print a negative Poisson's ratio structural plate. The printing parameters are set as follows: printing speed 40 mm / s, printing temperature within the material melting temperature range, printing layer thickness 0.1 mm, and filling density 100% to ensure structural integrity; select a casting mold made of polyurethane hard plastic material, place the negative Poisson's ratio structural plate in the casting mold, and set positioning pins for positioning.

[0066] S2. First, add cement, fly ash, silica fume, river sand and basalt coarse aggregate into the mixing equipment in proportion, dry mix at a mixing speed of 60r / min for 1.5min, add water and water reducing agent after mixing evenly, and stir at a mixing speed of 120r / min for 2min to form a uniform slurry; then gradually and evenly sprinkle the steel fiber into the mixer, and stir at a mixing speed of 120r / min for 4min to ensure that the steel fiber is evenly distributed in the mixture.

[0067] S3. Stir the mixture at a stirring speed of 150r / min for 3 minutes, and then pour it into the casting mold so that the mixture fills the cavity in the negative Poisson's ratio structural plate and the gap between the negative Poisson's ratio structural plate and the casting mold. Use a scraper and vibrator to remove bubbles and ensure density. The vibrator vibrates at a frequency of 30Hz for 3 minutes; then carry out standard curing (temperature is 20±2℃, humidity ≥95%), and after curing, use a concrete grinder to grind to eliminate surface defects, and cut and process according to specification requirements, and then carry out non-destructive testing to check the structural integrity and performance, and obtain protective devices.

[0068] Example 2

[0069] A protective device, which differs from Example 1 in that: the negative Poisson's ratio structural plate contains only one layer, the thickness of the protective device is 100 mm, and the dimension of the internal negative Poisson's ratio structural plate in the thickness direction is 70 mm.

[0070] Example 3

[0071] A protective device comprises a negative Poisson's ratio structural plate, wherein the cavity inside the negative Poisson's ratio structural plate and the periphery of the negative Poisson's ratio structural plate are filled with ultra-high performance concrete, and the thickness of the protective device is the same as that of Example 1.

[0072] The structure and size of the negative Poisson's ratio structural plate are the same as those of Example 1, except that the material is metal, specifically Ti-6Al-4V titanium alloy; in the negative Poisson's ratio structural plate, the dimension of the frame material in the thickness direction is 140 mm, and the thickness of the frame wall in the microcell is 10 mm.

[0073] The ultra-high performance concrete is composed of the following components in parts by weight: 360 parts of cement, 36 parts of silica fume, 36 parts of fly ash, 800 parts of fine aggregate, 800 parts of coarse aggregate, 39 parts of steel fiber, 120 parts of water and 5 parts of high-efficiency water reducing agent; the difference from Example 1 is that the coarse aggregate is selected as sintered bauxite coarse aggregate with a particle size of 5-8 mm, and the specifications of other components are the same as those in Example 1.

[0074] The difference between the preparation method and Example 1 is that: in S1, metal powder 3D printing technology is used, and metal powder is used as raw material for printing; the other steps are the same as in Example 1.

[0075] Example 4

[0076] A protective device comprises a negative Poisson's ratio structural plate, wherein the cavity inside the negative Poisson's ratio structural plate and the periphery of the negative Poisson's ratio structural plate are filled with ultra-high performance concrete, and the thickness of the protective device is the same as that of Example 1.

[0077] The material, structure and size of the negative Poisson's ratio structural plate are the same as those in Example 1.

[0078] The ultra-high performance concrete is composed of the following components in parts by weight: 520 parts of cement, 52 parts of silica fume, 52 parts of fly ash, 1000 parts of fine aggregate, 1000 parts of corundum coarse aggregate, 78 parts of steel fiber, 130 parts of water and 10 parts of high-efficiency water reducing agent; the difference from Example 1 is that the coarse aggregate is selected as corundum coarse aggregate with a particle size of 5-8 mm, and the specifications of other components are the same as those in Example 1.

[0079] The preparation method is the same as that in Example 1.

[0080] Comparative Example 1

[0081] A protective device, having the same thickness as that of Example 1, is made of ultra-high performance concrete and is composed of the following components in parts by weight: 400 parts of cement, 40 parts of silica fume, 40 parts of fly ash, 900 parts of river sand, 39 parts of steel fiber, 120 parts of water, and 8 parts of water reducer.

[0082] The difference from Example 1 is that no negative Poisson's ratio structural plate and basalt coarse aggregate are contained.

[0083] The preparation method is the same as the preparation and casting method of the ultra-high performance concrete in Example 1, and the curing conditions are the same.

[0084] Comparative Example 2

[0085] A protective device having the same thickness as that of Example 1, comprising ultra-high performance concrete, wherein a steel grid is arranged in the ultra-high performance concrete, wherein the upper and lower surfaces respectively use HRB400 grade steel bars with a diameter of 10 mm, and the steel bar spacing is 200 mm, and the steel bars on the upper and lower surfaces are respectively cross-arranged longitudinally and transversely to form a steel grid, and the stirrups use HRB400 grade steel bars with a diameter of 8 mm and a spacing of 200 mm.

[0086] The components of the ultra high performance concrete are the same as those in Example 1.

[0087] The preparation method is the same as that of Example 1, but the negative Poisson's ratio structural plate is replaced by the above-mentioned steel cage.

[0088] Comparative Example 3

[0089] A protective device, having the same thickness as that of Example 1, comprises a negative Poisson's ratio structural plate, wherein the cavity inside the negative Poisson's ratio structural plate and the periphery of the negative Poisson's ratio structural plate are filled with ultra-high performance concrete.

[0090] The material, structure and size of the negative Poisson's ratio structural plate are the same as those in Example 1.

[0091] The difference from Example 1 is that the ultra-high performance concrete does not contain basalt coarse aggregate.

[0092] The preparation method is the same as that in Example 1.

[0093] Experimental example

[0094] The protection devices of Examples 1 and 2 and Comparative Examples 1 to 3 were tested for their high-speed projectile penetration resistance performance, and the testing method included the following steps:

[0095] Step 1: Prepare the test object into a prismatic target with a projectile surface size of 500×500mm 2 The thickness in the ballistic direction is 100~150mm. A pointed egg-shaped projectile with a diameter of 28mm is used, and the projectile material is 30CrMnSiNi2A high-strength alloy steel (yield strength is 1466MPa, ultimate strength is 1770MPa, Rockwell hardness is 55HRC).

[0096] Step 2: Use a cannon to fire a bullet to hit the target in front of it. The bullet impact speed is set to 400m / s. During the process, a high-speed camera installed on the side of the trajectory is used to capture the movement of the projectile to obtain relevant parameters.

[0097] Step 3: Evaluate the anti-penetration performance of the target material by measuring the residual velocity after the bullet passes through the target, the number of concrete fragments falling on the target, the pit area on the impact surface, and the pit area on the back surface. The test results are shown in Table 1. In the table, the number of concrete fragments is 0-5, which is evaluated as "small"; the number is 6-15, which is evaluated as "medium"; the number of concrete fragments is 16-30, which is evaluated as "more"; the number is 31, which is evaluated as "many".

[0098] Table 1 Test results of high-speed projectile penetration resistance

[0099]

[0100] It can be seen from Table 1 that Example 1 demonstrates the excellent performance of the anti-penetration ultra-high performance concrete based on the negative Poisson's ratio structure. Under the condition of a target thickness of 150 mm, the residual velocity of the concrete is only 120 m / s, which is significantly lower than the residual velocity of other comparative examples. This shows that the concrete has a very strong ability to absorb impact energy and can effectively reduce the penetration speed of bullets. The small number of concrete fragments means that the concrete has strong impact resistance and resistance to fragment splashing. The pit areas of the impact surface and the back surface are 17671 mm 2 and 22698mm 2 , indicating that although the concrete has a certain degree of damage at the impact point and back, the damage area is smaller than that of other comparison ratios, reflecting its superior anti-penetration performance.

[0101] Example 2 is a concrete target with a relatively thin thickness, and its residual velocity is 130 m / s, which is slightly lower than that of Example 1. Although the number of concrete fragments is small, the pit areas of the impact surface and the back impact surface are close to those of Example 1. Due to the thin thickness of the target body, the overall anti-penetration performance is slightly inferior to that of Example 1, but still better than that of Comparative Examples 1 to 3.

[0102] Comparative Example 1 does not use negative Poisson's ratio structure and coarse aggregate, and only uses traditional UHPC materials; the test results show that at the same thickness, the residual velocity of the target is 200m / s, which is much higher than that of Example 1, indicating that traditional concrete is insufficient in absorbing impact energy; the number of concrete fragments is large, which means that its impact resistance and resistance to fragment splashing are poor. The pit area of ​​the impact surface and the back impact surface is large, 31,415mm² and 38,013mm² respectively, showing a larger damage range and worse protection effect.

[0103] Comparative Example 2 used traditional UHPC materials to remove coarse aggregate and added steel bars. Although the residual velocity of concrete was reduced (180 m / s), it was still higher than that of Example 1; this shows that adding steel bars has a certain improvement in anti-penetration performance, but the effect is not as significant as that of the negative Poisson's ratio structure. There are more concrete fragments, and the pit area on the impact surface and the back impact surface is larger, indicating that its impact resistance is slightly insufficient compared with Example 1.

[0104] Comparative Example 3 is an anti-penetration ultra-high performance concrete based on a negative Poisson's ratio structure, but no coarse aggregate is added. The residual velocity is 150 m / s, which is lower than that of Comparative Examples 1 and 2, but still higher than that of Example 1; the number of concrete fragments is moderate, and the pit area on the impact surface and the back impact surface is relatively small, showing a certain anti-penetration ability, but not as good as that of Example 1.

[0105] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A protective device, characterized in that: It comprises a negative Poisson's ratio structural plate, which is located inside the ultra-high performance concrete, and the cavity of the negative Poisson's ratio structural plate is filled with the ultra-high performance concrete; the negative Poisson's ratio structural plate comprises a double-arrow structural layer and a sinusoidal structural layer arranged in sequence along a direction perpendicular to the bullet-facing surface, the cross section of the double-arrow structural layer is a double-arrow-shaped negative Poisson's ratio structure, and the cross section of the sinusoidal structural layer is a sinusoidal negative Poisson's ratio structure; the sharp angle direction in the double-arrow structural layer is perpendicular to the bullet-facing surface, the wave crest of the sinusoidal structural layer is connected to the end of the sharp angle structure, and the sinusoidal structural layer is located on the side of the double-arrow structural layer away from the bullet-facing surface; The ultra-high performance concrete is composed of the following components in parts by weight: 360-520 parts of cement, 36-52 parts of silica fume, 36-52 parts of fly ash, 800-1000 parts of fine aggregate, 800-1000 parts of coarse aggregate, 39-78 parts of steel fiber, 120-130 parts of water and 5-10 parts of high-efficiency water reducing agent; The negative Poisson's ratio structural plate includes at least one layer of sheets, and each layer of sheets includes a plurality of micro cells connected to each other; the cross-sectional structure of the micro cells includes a frame surrounded by a first beam, a second beam and a bottom beam, the head ends of the first beam and the second beam are connected, and the tail ends of the first beam and the second beam are respectively opened to form a pointed structure; the two ends of the curved bottom beam are respectively connected to the tail ends of the first beam and the second beam; inside the frame, a pointed cross beam is connected between the first beam and the second beam, and the pointed cross beam has the same direction as the pointed structure, and outside the frame, the first beam and the second beam extend out of the first side beam and the second side beam respectively at an angle toward the tail end, and between adjacent micro cells, the first side beam and the second side beam are connected, and the tail end of the first beam is connected to the tail end of the second beam.

2. The protective device according to claim 1, characterized in that: Between adjacent sheets, the head ends of the first beam and the second beam are connected to the convex position of the bottom beam; with the angle bisector of the pointed structure as the axis of symmetry, the micro-cell is bilaterally symmetrical.

3. The protective device according to claim 1, characterized in that: The shape of the curved bottom beam comprises a sine curve, including a first sine curve segment and a second sine curve segment that are symmetrically arranged, and the first sine curve segment and the second sine curve segment are connected at a convex position.

4. The protection device according to claim 2, characterized in that: On the first beam, the extended position of the cross beam is located between the extended position and the tail end of the first side beam, and on the second beam, the extended position of the cross beam is located between the extended position and the tail end of the second side beam; The pointed cross beam is formed by connecting straight line segments extending from the first beam and the second beam respectively; the two ends of the pointed cross beam are respectively connected to the trisection points of the first beam and the second beam near the head end; the first side beam and the second side beam are respectively connected to the trisection points of the first beam and the second beam near the tail end; The first side beam extending from the first beam is parallel to the straight section of the extended pointed cross beam, and the second side beam extending from the second beam is parallel to the straight section of the extended pointed cross beam.

5. The protection device according to claim 1, characterized in that: The cement is 52.5 or 52.5R ordinary Portland cement; The silica fume has a silica mass percentage of not less than 97%, a volcanic ash activity index greater than 95%, and a specific surface area greater than 21.0 m² / g; The fly ash is Class I fly ash, with a loss on ignition of less than 3.0% and a specific surface area of ​​more than 1000 cm2 / g; The steel fiber is a straight steel fiber with a length of 13-15 mm; The high-efficiency water reducer is a polycarboxylate water reducer with a water reduction rate of >30%; The fine aggregate is natural river sand with a fineness modulus of 2.3 to 3.0; The material of the coarse aggregate includes one or more of basalt, sintered bauxite and corundum, and the particle size is 5-8 mm.

6. A method for preparing a protective device according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. preparing a negative Poisson's ratio structural plate, and placing the negative Poisson's ratio structural plate in a casting mold; S2. mixing to obtain a mixture of ultra-high performance concrete; S3. Pour the mixture into a mould so that the mixture fills the cavity in the negative Poisson's ratio structural plate and the gap between the negative Poisson's ratio structural plate and the pouring mould, and perform curing to obtain a protective device.

7. The preparation method according to claim 6, characterized in that: In S1, a negative Poisson's ratio structural plate is prepared by 3D printing or injection molding; In S2, cement, fly ash, silica fume, fine aggregate and coarse aggregate are mixed and dry-mixed, and then water and water reducing agent are added and stirred, and then steel fiber is added and stirred to obtain a uniform mixture; after adding steel fiber, the stirring speed is 100~130r / min, and the stirring time is 2.5~4min; In S3, the mixture is stirred at a stirring speed of 140-160 r / min before pouring, and the stirring time is 2-3 min.

8. An application of the protective device according to any one of claims 1 to 5, characterized in that: The applications include applications in protective facilities.

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