A lightweight ballistic protection device

Abstract

The application provides a light bulletproof device, which comprises a ceramic layer, a first reinforced polyvinyl chloride layer, a carbon fiber layer, a negative Poisson's ratio microstructure energy absorption layer and a second reinforced polyvinyl chloride layer in sequence. The light bulletproof device with hard surface layer and soft inner layer is designed by using the bionics principle. The outer layer of the device is composed of the ceramic layer and the first reinforced polyvinyl chloride layer. The ceramic layer and the first reinforced polyvinyl chloride layer first contact with the bullet, and the high strength and high hardness characteristics of the ceramic layer and the first reinforced polyvinyl chloride layer make the bullet rapidly passivated. The inner layer is composed of the negative Poisson's ratio microstructure energy absorption layer and the carbon fiber layer. The characteristics of the carbon fiber layer and the negative Poisson's ratio microstructure energy absorption layer make the inner layer can slowly release the stress transmitted from the outer layer and consume the residual kinetic energy of the bullet. Through the cooperation of the inner layer, the outer layer and the back layer (the second reinforced polyvinyl chloride layer), the bulletproof device designed by the application has good bulletproof and shock isolation performance.

Description

Technical Field

[0001] This invention relates to the field of bulletproof technology, and more specifically to a lightweight bulletproof device. Background Technology

[0002] Body armor, as an essential item in the military field, can protect the lives of combat personnel in critical moments. With the advancement of technology and the rapid development of the weapons manufacturing industry, the power of weapons such as guns and cannons is constantly increasing, which places new and higher demands on body armor.

[0003] Existing technology reports a novel biomimetic bulletproof vest with a ceramic outer layer, a composite material inner layer, and a high-strength epoxy resin bonding structure. The outer ceramic layer is designed as a columnar double-layer structure, separated by a metal frame to address the issue of a single ceramic piece being unable to withstand repeated impacts. Simultaneously, the frame structure can absorb some of the projectile's kinetic energy and completely constrain the ceramic layers, thus preventing premature breakage and fragmentation, enhancing the vest's bulletproof performance. However, when attacked by a bullet, this device cannot deflect it, causing the outer ceramic layer to bear all the bullet's kinetic energy, and the joints between the ceramic units are vulnerable to bullet damage, reducing the overall bulletproof effect. Furthermore, this vest has poor cushioning capacity against bullet impacts. Summary of the Invention

[0004] Therefore, the purpose of this invention is to provide a lightweight bulletproof device that can deflect bullets, effectively reduce the impact force of bullets, and has excellent effect in buffering the impact force of bullets.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] The present invention provides a lightweight bulletproof device, which comprises, in sequence, a ceramic layer, a first reinforced polyvinyl chloride layer, a carbon fiber layer, a negative Poisson's ratio microstructure energy-absorbing layer, and a second reinforced polyvinyl chloride layer;

[0007] The negative Poisson's ratio microstructure energy-absorbing layer is composed of multiple three-dimensional basic units, each of which includes a central "cross" body and "square" bodies surrounding the central "cross" body.

[0008] The central "cross" and "square" shapes are both composed of two-dimensional representative micro-cells. Each two-dimensional representative micro-cell is formed by four polygons filled with chiral microstructure units connected to each other. After being connected, the center of the two-dimensional representative micro-cell forms a rhomboid cavity.

[0009] Preferably, the central "cross" body comprises two mutually perpendicular two-dimensional representative microcells, and the two intersection points of the central "cross" body are located on the short axis of the rhomboid cavity.

[0010] Preferably, the polygon filled with chiral microstructure units is a quadrilateral.

[0011] Preferably, the two-dimensional representative microcell has a mirror structure in the Y-axis direction.

[0012] Preferably, the chiral microstructure unit consists of a circle and ribs surrounding the circle, one end of the ribs being tangent to the circle and the other end being connected to a vertex of the polygon, the circle being located at the center of the polygon filled with the chiral microstructure unit.

[0013] Preferably, the material of the negative Poisson's ratio microstructure energy-absorbing layer is any one or more of aluminum alloy, titanium alloy, or magnesium alloy.

[0014] Preferably, the ceramic layer has a plurality of three-dimensional micro-cells arranged in an array, and each three-dimensional micro-cell is composed of ceramic monomers in the form of regular polygonal frustums and ceramic monomers in the form of hemispheres.

[0015] Preferably, the number of sides of the regular polygonal frustum in the ceramic unit is any integer from 4 to 8.

[0016] The ceramic monomer is composed of any one or more of boron carbide, silicon carbide, or aluminum carbide.

[0017] Preferably, the plurality of three-dimensional microcells are filled with a filling material, which is selected from any one or more of phenolic epoxy resin, bisphenol A epoxy resin or waterborne epoxy resin.

[0018] Preferably, the first reinforced polyvinyl chloride layer and the second reinforced polyvinyl chloride layer are each composed of reinforcing fibers and polyvinyl chloride.

[0019] Preferably, the first reinforced polyvinyl chloride layer is composed of multiple layers, and the reinforcing fibers in the layers are arranged in a spiral gradient angle with each other.

[0020] Preferably, the second reinforced polyvinyl chloride layer is composed of multiple layers, and the reinforcing fibers in the layers are arranged in a spiral gradient angle with each other.

[0021] The reinforcing fiber is any one or more of glass fiber, polypropylene fiber, or aramid fiber.

[0022] Preferably, the carbon fiber layer is a composite carbon fiber layer.

[0023] Preferably, the composite carbon fiber layer is composed of carbon fiber and epoxy resin.

[0024] Preferably, the ceramic layer, the first reinforced polyvinyl chloride layer, the carbon fiber layer, the negative Poisson's ratio microstructure energy-absorbing layer, and the second reinforced polyvinyl chloride layer are bonded together by any one or more of epoxy resin adhesive, polyurethane adhesive, or structural adhesive.

[0025] Preferably, the ceramic layer has a thickness of 6-10 mm, the first reinforced polyvinyl chloride layer has a thickness of 3-6 mm, the carbon fiber layer has a thickness of 4-8 mm, the negative Poisson's ratio microstructure energy-absorbing layer has a thickness of 10-15 mm, and the second reinforced polyvinyl chloride layer has a thickness of 3-6 mm.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] This invention provides a lightweight bulletproof device, which sequentially comprises a ceramic layer, a first reinforced polyvinyl chloride (PVC) layer, a carbon fiber layer, a negative Poisson's ratio microstructure energy-absorbing layer, and a second reinforced PVC layer. Utilizing biomimetic principles and based on the characteristics of badger tooth enamel and dentin in nature, this invention designs a lightweight bulletproof device with a "hard outer layer and soft inner layer." The outer layer of the device consists of a ceramic layer and a first reinforced PVC layer, which are the first to contact the bullet, rapidly blunting it due to their high strength and hardness. The inner layer consists of a negative Poisson's ratio microstructure energy-absorbing layer and a carbon fiber layer. The carbon fiber layer possesses extremely high toughness, and the negative Poisson's ratio microstructure energy-absorbing layer exhibits a "compression-contraction" negative Poisson's ratio effect, effectively blocking the bullet's advance and altering its trajectory, reducing its impact velocity, and also possessing shock-absorbing and energy-absorbing properties. The characteristics of the carbon fiber layer and the negative Poisson's ratio microstructure energy-absorbing layer allow the inner layer to mitigate the stress transmitted from the outer layer and dissipate the bullet's remaining kinetic energy. The second PVC layer, serving as the back layer, isolates the negative Poisson's ratio microstructure energy-absorbing layer from the human body, improving wearer comfort. Simultaneously, the second PVC layer ensures a stronger bond to the negative Poisson's ratio microstructure energy-absorbing layer, enhancing the durability and stability of the bulletproof device. Through the coordinated action of the inner, outer, and back layers, the bulletproof device designed in this invention possesses excellent bulletproof and shock-absorbing performance. Attached Figure Description

[0028] Figure 1 (a) is a schematic diagram of badger teeth structure;

[0029] Figure 1 (b) is a diagram showing the overall structure of the lightweight bulletproof device of the present invention.

[0030] Among them, 1 is a ceramic layer, 2 is a first reinforced polyvinyl chloride layer, 3 is a carbon fiber layer, 4 is a negative Poisson's ratio microstructure energy absorption layer, and 5 is a second reinforced polyvinyl chloride layer.

[0031] Figure 2 (a) is a schematic diagram of the scales on the surface of an armadillo's body;

[0032] Figure 2 (b) is a schematic diagram of the array arrangement of several three-dimensional micro-cells of biomimetic armadillo scales;

[0033] Figure 2 (c) is a schematic diagram of the ceramic layer structure;

[0034] Figure 2 (d) is a schematic diagram of the intersection of a regular hexagonal frustum and a hemisphere;

[0035] Figure 3 (a) is a schematic diagram of the gradient Bouligand structure in the cuticle of a lobster;

[0036] Figure 3 (b) is a schematic diagram of the arrangement of reinforcing fibers in the first and second reinforced polyvinyl chloride layers;

[0037] Figure 4 This is a structural diagram of a two-dimensional representative microcell of the embedded four-chiral rotational microstructure unit of the present invention;

[0038] Figure 5 This is a schematic diagram of the arrangement of representative two-dimensional microcells of the embedded four-chiral rotational microstructure unit in the two-dimensional plane of the present invention.

[0039] Figure 6 This is a structural diagram of the three-dimensional basic unit in the negative Poisson's ratio microstructure energy-absorbing layer of this invention;

[0040] Figure 7 This is a schematic diagram of the arrangement of three-dimensional basic units in the negative Poisson's ratio microstructure energy-absorbing layer of the present invention;

[0041] Figure 8 This is a force diagram of the ceramic layer of the present invention when it is penetrated by a bullet;

[0042] Figure 9(a) is a diagram of the compression deformation mode at an impact velocity of 40 m / s for the present invention, which incorporates a four-chiral rotational microstructure and a hexagonal honeycomb structure.

[0043] Figure 9(b) is a time-specific energy absorption comparison of the embedded four-chiral rotational microstructure and hexagonal honeycomb structure at an impact velocity of 40 m / s;

[0044] Figure 9(c) shows a strain-stress comparison of embedded four-chiral rotational microstructures and hexagonal honeycomb structures at an impact velocity of 40 m / s.

[0045] Figure 10(a) shows the compression deformation mode at an impact velocity of 60 m / s for the embedded four-chiral rotational microstructure and hexagonal honeycomb structure;

[0046] Figure 10(b) shows the time-specific energy absorption comparison of the embedded four-chiral rotational microstructure and hexagonal honeycomb structure at an impact velocity of 60 m / s;

[0047] Figure 10(c) shows a strain-stress comparison of embedded four-chiral rotational microstructures and hexagonal honeycomb structures at an impact velocity of 60 m / s;

[0048] Figure 11(a) shows the compression deformation mode at an impact velocity of 90 m / s for the embedded four-chiral rotational microstructure and hexagonal honeycomb structure;

[0049] Figure 11(b) is a time-specific energy absorption comparison of the embedded four-chiral rotational microstructure and hexagonal honeycomb structure at an impact velocity of 90 m / s;

[0050] Figure 11(c) shows a strain-stress comparison of embedded four-chiral rotational microstructures and hexagonal honeycomb structures at an impact velocity of 90 m / s. Detailed Implementation

[0051] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0052] Terminology Explanation:

[0053] Negative Poisson's ratio effect: This refers to the phenomenon where, under tension, a material expands laterally within its elastic range; conversely, under compression, it contracts laterally. Generally, positive Poisson's ratio structures exhibit the characteristics of "compression-expansion, tension-contraction," while negative Poisson's ratio structures exhibit the opposite characteristics of "compression-contraction, tension-expansion."

[0054] Specific energy absorption: The energy absorbed per unit mass of a structure.

[0055] Stress: When an object deforms due to external factors such as force, humidity, and temperature field changes, internal forces are generated between the different parts of the object to resist the action of these external factors and attempt to restore the object from its deformed position to its original position.

[0056] Strain: refers to the local relative deformation of an object under the action of external forces and non-uniform temperature fields.

[0057] Bouligand structure: also known as spiral structure, is a three-dimensional structure formed by fibers arranged and stacked in a spiral at a certain angle in space.

[0058] Carbon fiber prepreg: Carbon fiber prepreg is a carbon fiber material that has been impregnated with epoxy resin during the manufacturing process. It has the characteristics of high strength, high stiffness and lightweight, and is widely used in aerospace, automotive, sporting goods and other fields.

[0059] Armadillo: The armadillo is an endangered reptile, also known as the cave rabbit or dough turtle, and belongs to the mammal family. Armadillos have a hard shell, similar to a turtle shell, which protects them from external harm.

[0060] Badger: Also known as Eurasian badger, the badger is widely distributed in Europe and Asia. It is a widely distributed omnivorous animal, characterized by its extremely sharp and tough teeth.

[0061] The purpose of this invention is to design a bulletproof device with excellent ballistic performance. The base material of the bulletproof device is a composite material of ceramics, carbon fiber, and polymers, with key references to structures found in nature such as armadillo scales, lobster claw keratin layer, and badger teeth, to improve the strength, toughness, energy absorption characteristics, and lightweight properties of the novel biomimetic bulletproof and shock-absorbing protective structure. This invention mainly employs a five-layer barrier, from the outside to the inside: a ceramic layer, a first reinforced polyvinyl chloride layer, a carbon fiber layer, a negative Poisson's ratio microstructure energy-absorbing layer, and a second reinforced polyvinyl chloride layer.

[0062] The ceramic unit of the ceramic layer is designed as a three-dimensional structure with a polygonal frustum and a hemisphere intersecting. Based on the arrangement of armadillo scales, the ceramic units are spliced ​​into regular polygons, with a preferred regular hexagonal arrangement structure. This ensures that the bullet penetrates the ceramic layer at an oblique angle across the entire surface, thus solving the problem of premature breakage and detachment of the ceramic layer when it is penetrated by the bullet. At the same time, the influence of the ceramic layer material and structural parameters on the structural strength of the ceramic layer is considered, thereby improving the ballistic resistance of the ceramic layer.

[0063] The first and second reinforced PVC layers use the same matrix material. Based on the gradient Bouligand structure in the lobster claw, the reinforcing fibers in both reinforced PVC layers are arranged in a gradient pattern, resulting in an interlaced arrangement of the internal reinforcing fiber defense lines. The first reinforced PVC layer can resist the detachment of the ceramic layer, and the two-layer reinforced PVC structure enhances the toughness and energy absorption characteristics of the bulletproof device, improving its overall bulletproof performance.

[0064] The carbon fiber layer is a composite carbon fiber layer, formed by orthogonal lamination of carbon fiber prepreg. The thickness of the carbon fiber layer is determined by the impact velocity and energy of the bullet. The high strength of the carbon fiber layer significantly reduces bullet velocity, decreasing the kinetic energy of the bullet entering the negative Poisson's ratio microstructure energy-absorbing layer.

[0065] The negative Poisson's ratio microstructure energy-absorbing layer serves functions such as guidance, deceleration, shock isolation, and energy absorption. The negative Poisson's ratio microstructure energy-absorbing layer designed in this invention possesses excellent negative Poisson's ratio characteristics, exhibiting significant "compression-contraction" deformation under stress. During this "compression-contraction" deformation, the internal microstructure absorbs the bullet's impact energy, reduces its velocity, and further enhances its impact resistance after deformation, thereby reducing the impact on the human body and improving the overall ballistic protection performance of the bulletproof device.

[0066] In this invention, the five layers are preferably bonded together using one or more of epoxy resin adhesive, polyurethane adhesive, or structural adhesive. Epoxy resin adhesive is preferred because it has excellent bonding properties and can bond with various materials to form a strong bond, improving the overall integrity of the final bulletproof device. Furthermore, the three-dimensional structure where the polygonal frustum and hemisphere of the ceramic layer intersect is preferably filled with a filler material. This filler material is selected from one or more of phenolic epoxy resin, bisphenol A epoxy resin, or water-based epoxy resin, preferably phenolic epoxy resin. This filler material serves as both adhesive and buffer, preventing lateral displacement of the ceramic monomers when penetrated by a bullet from damaging adjacent ceramic monomers, thus effectively improving the bulletproof performance of the ceramic panel.

[0067] To enable those skilled in the art to better understand the technical solution of the present invention, the lightweight bulletproof device of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0068] See Figure 1 The badger is a mammal belonging to the genus *Berberis* in the subfamily Mustelidae of the order Carnivora. It is robust and wedge-shaped. Badger teeth consist of three parts: canines, incisors, and molars. This invention primarily focuses on the canines. Figure 1 As shown in (a), a badger tooth consists of a crown and a root. The crown is covered with a hard, smooth enamel. Both the crown and root are composed of dentin, which is softer than enamel. The enamel is primarily composed of enamel prisms, which effectively resist large external forces. The dentin, located on the inner side of the tooth's cross-section, is soft and has good elasticity. When the enamel is subjected to external force, it can buffer chewing pressure, better protecting the tooth from breakage. Based on the characteristics of badger tooth enamel and dentin, this invention designs a gradient bulletproof model with a "hard outer layer and soft inner layer," namely the lightweight bulletproof device provided by this invention. Figure 1As shown in (b), the lightweight bulletproof device, from the outer side B to the inner side A (i.e., in the direction of the arrow), comprises the following overall structure: a ceramic layer 1, a first reinforced polyvinyl chloride layer 2, a carbon fiber layer 3, a negative Poisson's ratio microstructure energy-absorbing layer 4, and a second reinforced polyvinyl chloride layer 5. The outer side refers to the side of the lightweight bulletproof device that contacts the bullet, and the inner side refers to the side of the lightweight bulletproof device that contacts the protected object (such as a human body). In this invention, the outer layer of the lightweight bulletproof device consists of a ceramic layer and a first reinforced polyvinyl chloride layer. The ceramic layer and the first reinforced polyvinyl chloride layer are in contact with the bullet first, rapidly blunting it due to their high strength and high hardness. The inner layer consists of a negative Poisson's ratio microstructure energy-absorbing layer and a carbon fiber layer. The carbon fiber layer possesses extremely high toughness, while the negative Poisson's ratio material layer exhibits shock absorption and energy dissipation properties. The combined characteristics of the carbon fiber layer and the negative Poisson's ratio microstructure energy-absorbing layer allow the inner layer to mitigate the stress transmitted from the outer layer and dissipate the bullet's remaining kinetic energy. Simultaneously, the second reinforcing PVC layer in the outer layer acts as a backing layer, isolating the negative Poisson's ratio microstructure energy-absorbing layer from the wearer, improving comfort. Furthermore, the second reinforcing PVC layer ensures a stronger bond to the negative Poisson's ratio microstructure energy-absorbing layer, enhancing the durability and stability of the bulletproof device. This invention, through the synergy of the inner, outer, and backing layers, enables the designed lightweight bulletproof device to possess excellent bulletproof and shock-absorbing performance.

[0069] See Figure 2 The armadillo is a mammal that lives in arid regions of Africa and Asia. The armadillo's body is covered with hard scales (the scales are shaped like...) Figure 2 (a) As shown, the scales are the armadillo's defense mechanism. The scales are interconnected, forming a mesh structure that increases the overall strength and stability, helping them resist external damage. Based on the shape of the armadillo scales, this invention designs ceramic monomers with a base shape of a regular polygonal frustum and a hemispherical ceramic monomer. Each vertex of the upper or lower surface of the regular polygonal frustum in the ceramic monomer intersects with the hemisphere in the hemispherical ceramic monomer, resulting in a single three-dimensional micro-cell. The number of sides of the regular polygonal frustum in the ceramic monomer is any integer from 4 to 8, such as 4, 5, 6, 7, or 8. In some specific embodiments of this invention, taking a ceramic monomer with a regular hexagonal frustum as an example, the ceramic layer consists of several three-dimensional micro-cells arranged in an array, mainly mimicking the arrangement of armadillo scales. A schematic diagram of the arrangement is shown below. Figure 2 As shown in (b). In this case, a single three-dimensional micro-cell is formed by the intersection of the six vertices of the upper or lower surface of the hexagonal frustum in the ceramic monomer with the hemisphere in the ceramic monomer, as shown in (b). Figure 2 As shown in (d), the structural diagram of the ceramic layer finally formed by the array arrangement is as follows. Figure 2As shown in (c), in this invention, the spherical surface of the ceramic layer's hemisphere faces outwards and contacts the outside environment first. This ensures that when the lightweight bulletproof device is penetrated by a bullet, the bullet first contacts the spherical surface of the hemisphere. The spherical surface of the hemisphere can change the trajectory of the bullet, thus dispersing the force and blocking its advance. In this invention, both the ceramic monomers with regular polygonal frustums and the hemispherical ceramic monomers are composed of one or more of boron carbide, aluminum carbide, or silicon carbide, preferably boron carbide. This invention does not have any particular restrictions on the source of boron carbide, aluminum carbide, or silicon carbide; commercially available products are sufficient. Furthermore, this invention observes that armadillo scales are not in direct contact but are connected together through soft tissue. Based on this, this invention uses phenolic epoxy resin as a filler material to fill the spaces between adjacent individual three-dimensional microcells, avoiding damage to adjacent three-dimensional microcells caused by lateral displacement of the three-dimensional microcells when penetrated by a bullet, effectively improving the bulletproof performance of the ceramic layer.

[0070] See Figure 3 A gradient Bouligand structure exists in the cuticle of lobsters. Gradient Bouligand refers to the different arrangement of cuticle fibers between the outer and inner surfaces of the lobster claw, exhibiting a gradient angle structure. Specifically, the cuticle fibers on the outer surface of the lobster claw are arranged along the length of the claw, while the cuticle fibers on the inner surface are arranged in a ring shape. For example... Figure 3 As shown in (a), in the transition region between the two surfaces, the keratin fibers are arranged in a spiral pattern, a configuration known as the Bouligand gradient. This gradient structure makes the lobster claws harder and more durable. Figure 3 As shown in (b), this invention mimics the Bouligand structure between the inner and outer surfaces of the keratin layer of a lobster claw. The first reinforcing PVC layer consists of multiple layers, with the reinforcing fibers in each layer arranged in a spiral gradient angle. Similarly, the second reinforcing PVC layer consists of multiple layers, with the reinforcing fibers in each layer arranged in a spiral gradient angle. That is, in this invention, both the first and second reinforcing PVC layers are composed of multiple smaller layers. The arrangement of the reinforcing fibers in each individual smaller layer is consistent, but the arrangement of the reinforcing fibers between each smaller layer is different.

[0071] In this invention, the reinforcing fibers in the first and second reinforced PVC layers are independently arranged at a certain helical gradient angle, ranging from 10° to 30°, specifically 10°, 15°, 20°, 25°, or 30°, etc., so that the angles of the fibers in the first reinforced PVC layer are staggered. Similarly, the angles of the fibers in the second reinforced PVC layer are staggered. This provides better strength and stiffness to the first and second reinforced PVC layers with the same amount of material, and can resist stress from different directions, improving the overall performance of the lightweight bulletproof device. In some specific embodiments of this invention, the first and second reinforced PVC layers are each composed of reinforcing fibers and PVC. The reinforcing fibers are any one or more of glass fibers, polypropylene fibers, or aramid fibers, preferably glass fibers. That is, the material of the first and second reinforced PVC layers is fiber-reinforced PVC, preferably glass fiber-reinforced PVC. This invention does not impose any particular restrictions on the source of the fiber-reinforced polyvinyl chloride; any commercially available product will suffice.

[0072] In this invention, the negative Poisson's ratio microstructure energy-absorbing layer is composed of multiple sheets, each sheet containing multiple three-dimensional basic units. Each three-dimensional basic unit includes a central "cross" shape and "U"-shaped shapes surrounding the central "cross" shape. Both the central "cross" shape and the "U"-shaped shapes are composed of two-dimensional representative microcells. These two-dimensional representative microcells have a mirror structure along the Y-axis and are formed by interconnecting four polygons filled with chiral microstructure units. After interconnection, a rhomboid cavity is formed at the center of each two-dimensional representative microcell. The central "cross" shape contains two mutually perpendicular intersecting two-dimensional representative microcells, with the two intersection points of the central "cross" shape located on the minor axis of the rhomboid cavity. In this invention, the polygons filled with chiral microstructure units are quadrilaterals, preferably regular quadrilaterals. In some embodiments of this invention, the chiral microstructure units are cyclone-like structures filled within the regular quadrilaterals, specifically as follows... Figure 4 As shown, it consists of a circle and ribs surrounding the circle, one end of which is tangent to the circle and the other end of which is connected to a vertex of the polygon. The circle is located at the center of the polygon filled with chiral microstructure units, and the number of ribs is preferably 4.

[0073] In this invention, the chiral microstructure unit is designed such that the ridges and the circle are tangent. When deformed under stress, the chiral microstructure unit rotates around the center of the circle, while the four ridges move closer to the circle. This unique deformation mode of the chiral microstructure allows the two-dimensional microcell to produce greater elastic deformation and absorb more impact energy. Therefore, the presence of the chiral microstructure unit can improve the structural strength and energy absorption capacity of the negative Poisson's ratio microstructure energy-absorbing layer.

[0074] In some specific embodiments of the present invention, taking a regular quadrilateral filled with chiral microstructure units as an example, see [reference needed]. Figure 4 , Figure 4 A two-dimensional representative microcell for embedding four-chiral rotational microstructure units ( Figure 4 The two-dimensional representative microcell shown is a hollow structure (i.e., all areas except the gray areas are hollow). This two-dimensional representative microcell is composed of four interconnected regular quadrilaterals filled with chiral rotational microstructure units. The interconnected layout of the four regular quadrilaterals forms a rhombus-shaped cavity, which has two axes of symmetry: a major axis and a minor axis. The negative Poisson's ratio characteristic of the negative Poisson's ratio microstructure energy-absorbing layer designed in this invention is achieved by compressing the rhombus-shaped cavity. When the negative Poisson's ratio microstructure energy-absorbing layer is subjected to force in the Y direction, the four square structures move closer together in pairs, with the major axis of the rhombus-shaped cavity as the boundary. At the same time, the upper and lower pairs of regular quadrilaterals also move closer together, thus compressing the rhombus-shaped cavity and achieving the negative Poisson's ratio characteristic. This invention adds chiral microstructure units to four regular quadrilaterals, symmetrically arranged in pairs with the short axis of the rhombic cavities as the boundary, thereby reducing the porosity of the negative Poisson's ratio structure. This not only improves the seismic resistance and energy absorption characteristics of the negative Poisson's ratio microstructure energy-absorbing layer, but also prevents the negative Poisson's ratio microstructure energy-absorbing layer from overturning due to the torsional force generated by the deformation of the chiral microstructure units.

[0075] See Figure 5 , Figure 5 This is a schematic diagram of the two-dimensional planar arrangement of embedded four-chiral rotational microstructure units. As a whole, the aforementioned two-dimensional representative microcells are connected and repeatedly arranged along the horizontal direction (X-axis) and the vertical direction (Y-axis). In the horizontal direction, the vertices of the squares contained in adjacent two-dimensional representative microcells are connected to each other; the same connection method applies in the vertical direction. In the final arrangement, the major axes of the rhombic cavities of adjacent two-dimensional microcells are perpendicular to each other, i.e., the rhombic cavities are arranged alternately. Let rhombic cavity A be parallel to the X-axis, and rhombic cavity B be parallel to the Y-axis. In the final arrangement, the X-axis direction is rhombic cavity A, rhombic cavity B, rhombic cavity A, rhombic cavity B, i.e., rhombic cavity A or rhombic cavity B are arranged alternately, and the same applies in the Y-axis direction.

[0076] See Figure 6 , Figure 6It is a three-dimensional basic unit of the negative Poisson's ratio microstructure energy-absorbing layer. The three-dimensional basic unit takes a cube as the basic framework and is formed by arranging two-dimensional representative microcells in the cube in a specific manner. The specific manner is as follows: the Figure 4 shown two-dimensional representative microcell, in which the long axis of the diamond-shaped cavity of the two-dimensional representative microcell is parallel to the X axis, is rotated 90° around the short axis of its diamond-shaped cavity to form a central "cross" body. Centering on this central "cross" body, as shown in Figure 6 , the four square structures included in the central "cross" body on the Y-Z plane are grouped in pairs, and their top ends are respectively connected to the top ends of the long axes of the diamond-shaped cavities of the two-dimensional representative microcells whose diamond-shaped cavity long axes are parallel to the Z axis on the left and right sides; similarly, the same connection mode is adopted on the X-Z plane, forming a spatial layout with the central "cross" body and the "square-frame" body surrounding the central "cross" body.

[0077] Refer to Figure 7 , Figure 7 it is a planar arrangement schematic diagram of a certain layer of the negative Poisson's ratio microstructure energy-absorbing layer. As a whole, the three-dimensional representative microcells are connected and repeatedly arranged along the X-axis direction and Y-axis direction respectively to form a three-dimensional structure of a certain layer of the negative Poisson's ratio microstructure energy-absorbing layer. The structural parameters of the negative Poisson's ratio microstructure energy-absorbing layer can be further optimized and designed according to specific conditions, with the constraint that the structure has negative Poisson's ratio characteristics, and the goals of minimizing the relative density, maximizing the specific energy absorption, and optimizing the impact resistance, so as to obtain the optimal structural parameters. The material of the negative Poisson's ratio microstructure energy-absorbing layer can be any one or more of aluminum alloy, titanium alloy or magnesium alloy.

[0078] In the present invention, since the three-dimensional basic unit has the "compression-contraction" negative Poisson's ratio characteristic, when a bullet penetrates and impacts, the entire negative Poisson's ratio microstructure energy-absorbing layer will gather toward the interior of the structure, which further enhances its impact resistance, and greatly improves the bulletproof performance of the entire bulletproof device. In addition, the truss structure filled inside the negative Poisson's ratio microstructure energy-absorbing layer and the "compression-contraction" gathering and收拢 characteristic presented by the overall structure during the impact process can effectively block the advance of the bullet and change its movement direction, becoming an effective barrier to reduce the impact velocity of the bullet.

[0079] In the present invention, the carbon fiber layer is a composite carbon fiber layer. The composite carbon fiber layer is preferably composed of carbon fiber and epoxy resin. The composite carbon fiber layer has the characteristics of high strength, high rigidity, high heat resistance and the like. It can greatly consume the energy of the bullet during the process of resisting the penetration of the bullet, reduce the kinetic energy of the bullet entering the negative Poisson's ratio microstructure energy-absorbing layer, and improve the overall protection performance of the bulletproof device.

[0080] In some embodiments of the present invention, the thickness of the ceramic layer is 6-10 mm, preferably 7-8 mm; the thickness of the first reinforced polyvinyl chloride layer is 3-6 mm, preferably 4-5 mm; the thickness of the carbon fiber layer is 4-8 mm, preferably 5-6 mm; the thickness of the negative Poisson's ratio microstructure energy-absorbing layer is 10-15 mm, preferably 12-13 mm; and the thickness of the second reinforced polyvinyl chloride layer is 3-6 mm, preferably 4-5 mm. It should be noted that the thickness of each layer can be adjusted according to actual needs and is not limited thereto.

[0081] refer to Figure 8 , Figure 8 This diagram illustrates the principle behind the ceramic layer designed for full-area oblique penetration of a bullet in this invention. As shown, the ceramic unit is designed as a structure where a regular hexagonal frustum intersects with a hemisphere, where the radius of the hemisphere is equal to the side length of the hexagon. The ceramic units are then assembled into a hexagonal layer. The ceramic unit is relatively hard, and the curved surface of one side of the bullet contacts the curved surface of the ceramic unit (i.e., the spherical surface of the hemisphere). The bullet is subjected to a backward oblique force F. N The bullet's trajectory is opposite to its collinearity, causing it to deflect and thus enabling the ceramic layer to penetrate obliquely across its entire surface.

[0082] Referring to Figures 9, 10, and 11, respectively, at impact velocities of 40 m / s, 60 m / s, and 90 m / s, the deformation patterns (a), specific energy absorption curves (b), and stress-strain curves (c) of the composite microstructure of the negative Poisson's ratio microstructure energy-absorbing layer described in this invention and the traditional hexagonal honeycomb structure are shown. Referring to Figure 9(a), compared to the traditional hexagonal honeycomb, the composite microstructure of the negative Poisson's ratio microstructure energy-absorbing layer described in this invention, i.e., the embedded four-chiral rotational microstructure units, exhibits a "compression-contraction" negative Poisson's ratio characteristic during compression, causing the entire structure to become increasingly compacted and exhibiting an overall "contraction" deformation pattern, while the hexagonal honeycomb exhibits a layer-by-layer crushing overall deformation pattern. Referring to Figure 9(b), at an impact velocity of 40 m / s, the specific energy absorption of both the embedded four-chiral rotational microstructure and the traditional hexagonal honeycomb structure shows an increasing trend, and the specific energy absorption of the embedded four-chiral rotational microstructure is greater than that of the hexagonal honeycomb structure. Referring to Figure 9(c), at a compression velocity of 40 m / s, the stress of both the embedded four-chiral rotational microstructure and the hexagonal honeycomb structure increases with strain. Furthermore, at the same strain, the stress of the embedded four-chiral rotational microstructure unit is greater than that of the hexagonal honeycomb structure. The embedded four-chiral rotational microstructure also exhibits a significant plateau stress enhancement zone. The appearance of this plateau stress enhancement zone results in a higher specific energy absorption of the embedded four-chiral rotational microstructure unit compared to the traditional hexagonal honeycomb, consistent with the conclusion in Figure 9(b). This demonstrates that, compared to the traditional hexagonal honeycomb, the embedded four-chiral rotational microstructure unit possesses superior energy absorption characteristics at an impact velocity of 40 m / s. Similarly, Figures 10 and 11 show that the deformation mode, specific energy absorption-time variation law, and stress-strain variation law of the embedded four-chiral rotational microstructure at impact velocities of 60 m / s and 90 m / s are basically the same as those in Figure 9. Therefore, the embedded four-chiral rotational microstructure unit designed in this invention has a higher specific energy absorption than the traditional hexagonal honeycomb and exhibits superior impact energy absorption characteristics.

[0083] Based on the above, the technical solution of the present invention has the following advantages:

[0084] 1) This invention designs a novel negative Poisson's ratio microstructure unit. The microstructure unit has a negative Poisson's ratio characteristic of "compression-contraction". When a bullet impacts with a velocity v, different forces are generated in different positions and directions due to different degrees of contraction, causing the bullet to deviate irregularly towards the pores, ultimately achieving a guiding effect. In addition, the microstructure unit has porous medium characteristics, which provides a large amount of buffer deformation space and a more stable and efficient energy absorption process during compression. When applied to bulletproof devices, it can improve shock resistance and energy absorption characteristics while reducing the weight of the bulletproof device.

[0085] 2) Applying biomimetic principles and based on the armadillo scale arrangement structure, a three-dimensional structure was designed for each ceramic unit, featuring the intersection of a regular hexagonal prism and a hemisphere. These ceramic units were then assembled into a hexagonal arrangement. The spherical surface of the hemisphere caused the bullet to experience a backward tilting force F. N The bullet is not collinear with the direction of its movement, and the bullet tends to deflect, so that the bullet can penetrate the ceramic structure at an oblique angle across the entire area. At the same time, the ceramic layer is filled with a buffer medium, which prevents the lateral displacement of the ceramic layer caused by the bullet penetration from damaging adjacent ceramic units, thus effectively improving the ballistic performance of the ceramic layer.

[0086] 3) Utilizing biomimetic principles and based on the gradient Bouligand structure found in lobster claws, the reinforcing fibers of two layers of reinforced polyvinyl chloride are arranged in a gradient pattern, resulting in an interlaced internal fiber arrangement. This structure enhances the toughness and energy absorption properties of the bulletproof device, improving its overall bulletproof performance.

[0087] 4) Utilizing biomimetic principles and the characteristics of badger teeth, a gradient bulletproof model with a "hard outer layer and soft inner layer" is established. The high strength and rigidity of the hard layer blunts the bullet, while the soft layer releases the stress transmitted from the outer layer and consumes the bullet's remaining kinetic energy. The hard and soft layers work together to improve the bulletproof device's ability to withstand multiple bullet impacts.

[0088] 5) The negative Poisson's ratio microstructure energy-absorbing layer and ceramic layer designed in this invention can both change the trajectory of the bullet, greatly reduce the damage of the bullet to the human body, and have strong bulletproof capabilities.

[0089] 6) The materials used in each layer of this invention are all relatively lightweight materials, which are lighter and easier to carry than traditional materials, while having strong bulletproof capabilities, thus improving the mobility and survivability of combat personnel.

[0090] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A lightweight bulletproof device, characterized in that, It consists of, in sequence, a ceramic layer, a first reinforced polyvinyl chloride layer, a carbon fiber layer, a negative Poisson's ratio microstructure energy-absorbing layer, and a second reinforced polyvinyl chloride layer; The negative Poisson's ratio microstructure energy-absorbing layer is composed of multiple three-dimensional basic units, each of which includes a central "cross" body and "square" bodies surrounding the central "cross" body. The central "cross" and "square" shapes are both composed of two-dimensional representative micro-cells. Each two-dimensional representative micro-cell is formed by four polygons filled with chiral microstructure units connected to each other. After being connected, the center of the two-dimensional representative micro-cell forms a rhomboid cavity. The central "cross" contains two mutually perpendicular two-dimensional representative micro-cells, and the two intersection points of the central "cross" are located on the short axis of the rhomboid cavity. The polygon filled with chiral microstructure units is a quadrilateral; The two-dimensional representative microcell has a mirror structure; The chiral microstructure unit consists of a circle and ribs surrounding the circle. One end of each rib is tangent to the circle, and the other end is connected to a vertex of the polygon. The circle is located at the center of the polygon filled with the chiral microstructure unit. The ceramic layer has several three-dimensional micro-cells arranged in an array. Each three-dimensional micro-cell is composed of ceramic monomers in the form of regular polygonal frustums and ceramic monomers in the form of hemispheres.

2. The lightweight bulletproof device according to claim 1, characterized in that, The material of the negative Poisson's ratio microstructure energy-absorbing layer is any one or more of aluminum alloy, titanium alloy, or magnesium alloy.

3. The lightweight bulletproof device according to claim 1, characterized in that, The number of sides of the regular polygonal frustum in the ceramic unit is any integer from 4 to 8; The ceramic monomer is composed of any one or more of boron carbide, aluminum carbide, or silicon carbide.

4. The lightweight bulletproof device according to claim 1, characterized in that, The plurality of three-dimensional micro-cells are filled with a filling material, which is selected from any one or more of phenolic epoxy resin, bisphenol A epoxy resin or water-based epoxy resin.

5. The lightweight bulletproof device according to claim 1, characterized in that, The first reinforced polyvinyl chloride layer and the second reinforced polyvinyl chloride layer are each composed of reinforcing fibers and polyvinyl chloride; The first reinforced polyvinyl chloride layer is composed of multiple layers, and the reinforcing fibers in the layers are arranged in a spiral gradient angle with each other; The second reinforced polyvinyl chloride layer consists of multiple layers, with the reinforcing fibers in each layer arranged in a spiral gradient angle. The reinforcing fiber is any one or more of glass fiber, polypropylene fiber, or aramid fiber.

6. The lightweight bulletproof device according to claim 1, characterized in that, The carbon fiber layer is a composite carbon fiber layer; The composite carbon fiber layer is composed of carbon fiber and epoxy resin.

7. The lightweight bulletproof device according to claim 1, characterized in that, The ceramic layer, the first reinforced polyvinyl chloride layer, the carbon fiber layer, the negative Poisson's ratio microstructure energy-absorbing layer, and the second reinforced polyvinyl chloride layer are bonded together by any one or more of epoxy resin adhesive, polyurethane adhesive, or structural adhesive.

8. The lightweight bulletproof device according to claim 1, characterized in that, The ceramic layer has a thickness of 6-10 mm, the first reinforced polyvinyl chloride layer has a thickness of 3-6 mm, the carbon fiber layer has a thickness of 4-8 mm, the negative Poisson's ratio microstructure energy-absorbing layer has a thickness of 10-15 mm, and the second reinforced polyvinyl chloride layer has a thickness of 3-6 mm.

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