A UD structure multi-directional lay-up ballistic and impact resistant composite material and a lay-up system thereof

Abstract

The application provides a UD structure multidirectional laying bulletproof impact-resistant composite material, which comprises eight layers of fiber layers laid at different fiber axis deflection angles, and the laying sequence is spiral and orthogonal; a method for preparing the composite material; first, UD sheets are prepared, a continuous fiber 3D printer is used as a laying device, unidirectional tapes or fiber filaments are printed on a printing platform, and after repeated laying of the unidirectional tapes arranged closely, cutting is performed, or repeated laying of the filaments is performed, to prepare a single-layer UD sheet; then, the UD sheet is dipped in glue and coated with a film, and then hot pressing is performed; finally, a plurality of single-layer UD plates with different fiber axis orientations are glued and stacked layer by layer, and then hot pressing is performed again to prepare an eight-way UD bulletproof impact-resistant composite material. The multidirectional structure in the application improves the isotropy of the composite material to 99.98%, and improves the bulletproof impact-resistant performance; the preparation method improves the utilization rate of raw materials, and further improves the bulletproof impact-resistant performance by improving the integrity of the UD sheet and the internal friction.

Description

Technical Field

[0001] This invention relates to the field of bulletproof and impact-resistant composite materials, specifically to a UD-structured multi-directional lay-up bulletproof and impact-resistant composite material with superior bulletproof and impact-resistant performance compared to traditional unidirectional (UD) composite materials, and its lay-up method. Background Technology

[0002] The development of bulletproof materials is undergoing significant changes. In the 1840s, hard bulletproof materials using metals such as aluminum alloys, titanium alloys, and special steels began to appear. These bulletproof materials were heavy, which was detrimental to the wearer's mobility and comfort, and the metal could produce fragments when shot, causing secondary injuries to the wearer. With the advent of synthetic fiber technology, high-performance fiber composite materials have gradually become the mainstream bulletproof materials.

[0003] For fiber raw materials, high-performance fibers possess characteristics such as high strength and modulus, low density, and high temperature resistance. Examples include aramid fibers, high-strength polyethylene fibers, PBO fibers, carbon fibers, and glass fibers, which have been widely used in high-performance composite materials. For fabric structures, they mainly take the form of woven fabrics, unidirectional non-woven fabrics (UD fabrics), and biaxial warp (weft) woven fabrics.

[0004] The basic structure of UD fabric consists of two or more unidirectionally arranged sheets, cross-laid at specific fiber axis rotation angles (mostly 0° / 90° / 0° / 90°). These layers are then bonded together using special adhesives to form a flexible sheet, which is provided as the basic finished material to downstream users for processing into bulletproof products. This production method avoids fiber damage during weaving, ensuring that the fiber's strength, modulus, and other mechanical properties remain unaffected. Furthermore, the fibers are arranged parallel and straight within the matrix material, without interlacing points, allowing for rapid transmission of stress waves and absorption and diffusion of impact energy. Therefore, it has become an important method for improving the ballistic protection performance and reducing the weight of bulletproof materials, and is widely used in military and police bulletproof protection fields.

[0005] Currently, the fiber axis rotation angles in UD fabrics (i.e., UD bulletproof materials) are mostly 0° / 90°, with only two directions. This results in poor isotropic mechanical properties and room for improvement in ballistic performance. One approach is to distribute the orientation of multiple UD sheets evenly between 0° and 180° during layup to achieve overall structural isotropy. However, for this type of multi-directional UD-structured bulletproof material, the traditional layup method of directly using finished UD sheets requires cutting a significantly larger area of ​​the inclined UD sheet compared to the vertical UD sheet to ensure uniform layup. High-performance fibers are expensive due to the scarcity of raw materials and the complexity of processing. This production method would significantly increase manufacturing costs, leading to material waste and low production efficiency.

[0006] In order to improve the isotropy of the product, effectively reduce the back concavity depth after firing, increase the deformation area and thus improve the ballistic protection performance, while increasing the utilization rate of raw materials in the multi-directional UD fabric layer and reducing carbon emissions during the large-scale production process, it is necessary to develop a multi-directional UD structure ballistic and impact-resistant composite material and its preparation method. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the purpose of this invention is to provide a UD structure multi-directional lay-up bulletproof and impact-resistant composite material and its preparation method.

[0008] The objective of this invention is achieved through the following solution.

[0009] A UD structure multi-directional lay-up bulletproof and impact-resistant composite material is composed of multiple layers of UD sheets with different fiber rotation angles, which are glued, stacked, and hot-pressed.

[0010] In the above technical solution, the rotation angle of the UD sheet is distributed in a spiral manner, that is, the UD fabric is cyclically laid from bottom to top in the order of 0° / 22.5° / 45° / 67.5° / 90° / 112.5° / 135° / 157.5° of the fiber axis direction, wherein the fiber axis deflection between any two adjacent layers of sheet differs by 22.5°.

[0011] In the above technical solution, the rotation angle distribution of the UD sheet is orthogonal, that is, the UD fabric is cyclically laid from bottom to top in the order of 0° / 90° / 22.5° / 112.5° / 45° / 135° / 67.5° / 157.5° along the fiber axis. The fiber deflection angle between odd-numbered layers of sheet differs by 22.5°, the fiber deflection angle between even-numbered layers of sheet differs by 22.5°, and the difference between the upper odd-numbered layer and the lower even-numbered layer between adjacent layers is 90°.

[0012] In the above technical solution, the number of UD fabric layers is 8. With this number of layers, the back concave shape of the composite material under ballistic penetration changes from a cross shape to a circle, achieving the maximum deformable fiber area ratio. At this time, the in-plane mechanical properties approach the degree of isotropy (isotropy) of 99.98%. On this basis, the effect of further increasing the number of fiber axial directions on isotropy is negligible. Therefore, 8 directions are determined to be the optimal number of fiber axial directions for multi-directional UD structure.

[0013] A preparation method for preparing the aforementioned UD structure multi-directional lay-up bulletproof and impact-resistant composite material includes the following steps:

[0014] Step 1: Prepare a single-layer UD sheet. Use unidirectional tape or fiber monofilament as raw material and lay the raw material into a single-layer UD sheet of a certain size according to a certain orientation angle using a layup equipment.

[0015] Step 2: After stacking the single-layer UD sheets with different fiber axis orientations prepared in the above steps, place them in an impregnation tank for impregnation and coating, and then perform hot pressing. The adhesive layer is made of epoxy resin film with a peel strength greater than 1N / mm and accounts for 10-20% of the mass of the bulletproof material. The hot pressing temperature is set to 130±2℃ and the pressure is set to 16Mpa. After maintaining this temperature and pressure for 1 hour, the press is turned off and cooled to room temperature for 30-60 minutes to produce a UD structure multi-directional lay-up bulletproof and impact-resistant composite material.

[0016] It should be noted that the present invention can use various feasible thermosetting resin adhesive materials, including polyurethane film, PE film, SEBS hot melt adhesive, etc. The present invention does not limit the specific type of thermosetting resin adhesive used.

[0017] In the above technical solution, when using unidirectional tape for layup, the width of the unidirectional tape can be determined according to the required sheet size and layup angle. Assuming the long side of the UD sheet prepared by unidirectional tape layup is a, the short side is b, the unidirectional tape rotation angle is θ, and the unidirectional tape width is h, the unidirectional tape width can be obtained according to the geometric relationship of layup as follows:

[0018] In the above technical solution, when using unidirectional tape layup, multiple unidirectional tapes with predetermined widths and layup angles are arranged closely on a plane to form a single-layer fiber UD sheet. However, when using the traditional cutting method for layup, a single layer of unidirectional fabric forms a single-layer fiber UD sheet. The width of the unidirectional fabric required for layup along the diagonal of the sheet is much greater than the width required for layup along the parallel side. Since the width of unidirectional fabric is constant and limited during industrial production, the width of unidirectional fabric may not meet the size requirements of the fabrication, resulting in a limited layup angle. Unidirectional tape layup overcomes the width limitation by splicing multiple unidirectional tapes, further increasing the size of the sheet that can be prepared by multidirectional layup, and realizing layup with arbitrary width and angle.

[0019] In the above technical solution, a continuous fiber 3D printer can be used as a layup device to cut high-performance fiber unidirectional fabric that has been mass-produced into unidirectional strips of equal width along the axial direction, and perform high-precision layup to eliminate the gaps between the unidirectional strips, so that the unidirectional strips are printed tightly arranged on the plane, and finally form single-layer fiber UD sheets with different axes.

[0020] In the above technical solution, a continuous fiber 3D printer can be used as a layup device to print the fiber monofilaments tightly arranged on a plane, perform high-precision layup to eliminate gaps between monofilaments, and finally form single-layer fiber UD sheets with different axes.

[0021] In the above technical solutions, the printing size depends on the printer size.

[0022] In the above technical solution, when the laying equipment is a continuous fiber 3D printer, two different laying methods can be achieved by changing the print head.

[0023] In the above technical solution, when using a unidirectional tape printhead for tape laying, the fiber unidirectional tape enters the printhead through the feed port, is clamped by three pairs of counter-rotating rollers built into the printhead, and is pushed out of the printhead. Then, it is printed onto a pre-laid adhesive printing platform through the front pressure roller. After printing one unidirectional tape, the scissors built into the printhead will cut the fiber unidirectional tape. Then, the robotic arm moves the printhead to print the second unidirectional tape. The position of the printhead is precisely controlled by the motor to make the second unidirectional tape closely aligned with the first unidirectional tape, eliminating the gaps between the unidirectional tapes. This process is repeated until the laying is completed and then cut to obtain a single-layer fiber UD sheet.

[0024] In the above technical solution, when using a monofilament printhead for individual fiber laying, the fiber monofilament enters the printhead through the feed port, is held by three pairs of counter-rotating rollers inside the printhead and pushed out of the printhead, and then is printed onto the pre-laid adhesive printing platform through the front pressure roller. After printing one fiber, the built-in scissors in the printhead cut the fiber monofilament, and then the robotic arm moves the printhead to print the second fiber. The position of the printhead is precisely controlled by the motor to make the second fiber filament closely arranged with the first fiber filament, eliminating the gaps between the fiber filaments. This process is repeated until the single-layer fiber UD sheet is printed.

[0025] In the above technical solution, when using a unidirectional tape to lay high-performance fiber UD sheets as printing material, it is only necessary to cut off the excess material with serrated edges after the laying is completed to obtain a single-layer UD sheet at any angle. Compared with the traditional method of directly using finished UD sheets for laying, this method greatly improves the utilization rate of raw materials, reduces production costs, and is suitable for large-scale industrial production.

[0026] In the above technical solution, when using fiber monofilaments to lay high-performance fiber UID sheets as printing materials, no further cutting is required after laying, and a single-layer UD sheet at any angle can be obtained. Compared with the method of laying UD sheets, this method further improves the utilization rate of raw materials.

[0027] In the above technical solutions, the covering equipment can also be other equipment such as a robotic arm or manual covering.

[0028] The effective effects of this invention are as follows:

[0029] 1. The UD structure multi-directional lay-up bulletproof and impact-resistant composite material prepared by the present invention is formed by bonding, stacking and hot pressing 8 layers of UD sheets with different fiber axis orientations. The overall isotropy of the material is optimized. When a bullet hits, the impact shape on the material surface changes from a cross shape to a circle, and the proportion of deformed fiber area increases, thereby achieving isotropy of mechanical properties, effectively reducing the back concavity depth and significantly improving the bulletproof and impact-resistant performance of the UD bulletproof composite material.

[0030] 2. The present invention proposes a method for preparing UD structure multi-directional lay-up bulletproof and impact-resistant composite materials. Using multiple unidirectional tapes or monofilaments with predetermined widths and lay-up angles as raw materials, and utilizing the tight splicing of these tapes or monofilaments, sheets can be produced after lay-up by trimming excess material with serrated edges, or even without trimming. This overcomes the problem of traditional lay-up methods using unidirectional fabric for multi-directional lay-up, where the width of industrially produced unidirectional fabric cannot meet the dimensional requirements for multi-directional lay-up, resulting in limited lay-up angles and significant material waste during trimming. This method further improves the size of sheets that can be prepared by multi-directional lay-up and the material utilization rate, and achieves lay-up with arbitrary bandwidth and angles. Furthermore, it proposes using a continuous fiber 3D printer as the lay-up equipment for high-precision lay-up, eliminating gaps between unidirectional tapes or monofilaments, and further improving the mechanical properties of UD structure multi-directional lay-up bulletproof and impact-resistant composite materials. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of a multi-directionally laid ballistic and impact-resistant composite material with a spiral-laid UD structure.

[0032] Figure 2 This is a schematic diagram of a multi-directionally laid ballistic and impact-resistant composite material with an orthogonal UD structure.

[0033] Figure 3 A schematic diagram of a unidirectional tape layup method for a UD structure multi-directional layup ballistic and impact-resistant composite material.

[0034] Figure 4 A schematic diagram of a fiber monofilament layup method for a UD structure multi-directional layup bulletproof and impact-resistant composite material.

[0035] Figure 5 A schematic diagram of a continuous fiber 3D printer printhead used for laying unidirectional tape.

[0036] Figure 6 A schematic diagram of a continuous fiber 3D printer printhead used for laying up monofilament fibers.

[0037] Figure 7 This is a schematic diagram of the preparation of UD structure multi-directional lay-up bulletproof and impact-resistant composite materials using traditional lay-up cutting methods.

[0038] Figure 8This is a schematic diagram of the preparation of UD sheet using the unidirectional tape layup method in this invention. Detailed Implementation

[0039] The following detailed description of the UD structure multi-directional lay-up bulletproof and impact-resistant composite material and its lay-up system of the present invention, with reference to the accompanying drawings, is provided in detail.

[0040] Example 1

[0041] This invention provides a UD-structured multi-directionally laid ballistic and impact-resistant composite material, such as... Figure 1 As shown, the UD sheet consists of 8 layers from bottom to top, arranged in a spiral pattern. That is, the UD fabric is laid out in a cyclical manner from bottom to top (layer A to layer F) in the order of deflection angles relative to the fiber axis of 0° / 22.5° / 45° / 67.5° / 90° / 112.5° / 135° / 157.5°. The 0° direction shown in the figure is the fiber axis direction. The fiber axis deflection angle between any two adjacent layers differs by 22.5°. The fiber raw material used is ultra-high molecular weight polyethylene fiber.

[0042] Example 2

[0043] This invention provides a UD-structured multi-directionally laid ballistic and impact-resistant composite material, such as... Figure 2 As shown, the UD sheet consists of 8 layers from bottom to top, arranged in an orthogonal pattern. The UD fabric is laid out in a cyclical manner from bottom to top (layer A to layer F) with deflection angles relative to the fiber axis of 0° / 90° / 22.5° / 112.5° / 45° / 135° / 67.5° / 157.5° respectively. The 0° direction shown in the figure is the fiber axis direction. The fiber deflection angles between odd-numbered layers and even-numbered layers differ by 22.5°. The deflection angle between the lower odd-numbered layer and the upper even-numbered layer of adjacent layers differs by 90°. The fiber raw material is ultra-high molecular weight polyethylene fiber.

[0044] Example 3

[0045] A multi-directionally laid bulletproof and impact-resistant composite material with a UD structure is divided into 8 layers of UD sheets from bottom to top. Unlike Examples 1 and 2, the 8 layers of UD sheets are arranged in only two directions. The UD fabric is laid in a cyclic manner from bottom to top (layer A to layer F) according to the deflection angles with the fiber axis of 0° / 90° / 0° / 90° / 0° / 90° / 0° / 90° respectively. The fiber axis deflection between any two adjacent layers of sheets differs by 90°. The fiber raw material is ultra-high molecular weight polyethylene fiber.

[0046] The bulletproof and impact-resistant composite materials described in Examples 1-3 are all prepared by the following steps: Step 1: Eight layers are laid using unidirectional tapes of different widths. The number of unidirectional tapes, n, is set to 8. The long side length a of the laid UD sheet is 335mm, and the short side length b of the laid UD sheet is 270mm. The width is determined according to... Therefore, when θ = 0°, h = 33.75 mm; when θ = 22.5° or 157.5°, h = 47.21 mm; when θ = 45° or 135°, h = 53.47 mm; when θ = 67.5° or 112.5°, h = 51.60 mm; and when θ = 90°, h = 41.88 mm. After manual laying, according to... Figure 8 The method shown involves trimming excess material with serrated edges. The fiber UD sheet, with length and width ab and a fiber axis rotation angle θ, is obtained by laying several unidirectional fiber strips of varying lengths and widths h tightly arranged along the axial direction θ and then cutting them. Compared to using a single piece of unidirectional fabric with side length αβ, this significantly reduces material waste, resulting in single-layer UD sheets with different fiber axis orientations. Step 2: The single-layer UD sheets with different fiber axis orientations prepared in the above steps are glued together layer by layer and then hot-pressed. The adhesive layer is an epoxy resin film with a peel strength greater than 1 N / mm. The adhesive layer accounts for 10-20% of the mass of the bulletproof material. The hot-pressing temperature is set to 130±2℃, and the pressure is set to 16 MPa. This temperature and pressure are maintained for 1 hour, then the press is turned off, and the material is cooled to room temperature for 30-60 minutes, ultimately producing a bulletproof and impact-resistant composite material.

[0047] Comparative Example 1

[0048] A multi-directionally laid-out ballistic and impact-resistant composite material with a UD structure is disclosed. The fiber and UD sheet preparation structure are the same as in Example 3, differing only in the laying-out step of the preparation method. The ballistic and impact-resistant composite material described in Comparative Example 1 is prepared by the following steps: Step 1: Laying out finished UD sheets of different sizes, trimming excess material, such as... Figure 7 As shown, single-layer UD sheets with different fiber axis orientations are prepared, where I is the area to be cut away and J is the sheet to be retained after cutting. Step two is the same as in Examples 1-3, and finally, a multi-directionally laid-out ballistic and impact-resistant composite material with an UD structure is produced.

[0049] The bulletproof and impact-resistant composite materials in Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2 were subjected to performance tests. The indentation depth of the composite materials was tested in accordance with the Level 2 protection requirements of the standard GA141-2010 "Police Bulletproof Vest". A Type 54 7.62mm pistol was used to carry out a fixed-point, uninterrupted six-shot ballistic penetration test on each fiber composite bulletproof plate with 7.62mm×25mm Type 51 lead-core bullets. The penetration of the bulletproof target plate and the back indentation depth (BFS) were recorded.

[0050] The data comparison results are shown in Table 1:

[0051]

[0052] Comparing Examples 1, 2, and 3, it can be seen that when using manual unidirectional tape application, the helical and orthogonal 8-directional structures, compared to the traditional 2UD structure, reduce the back concavity depth caused by the first shot by approximately 51.1% and 63.5%, respectively; the back concavity depth caused by the first three shots by approximately 17.2% and 41.5%, respectively; and the average back concavity depth of the six shots by approximately 14.0% and 34.0%, respectively. This fully demonstrates the significant advantage of the 8-directional structure in reducing non-penetrating ballistic penetration damage. On the other hand, as the firing sequence increases, the effect of the 8-directional structure in reducing back concavity depth gradually weakens. This may be because when no ballistic penetration is encountered, the structure of the ballistic target plate remains intact, and its anti-ballistic penetration performance can be fully utilized. However, after the internal structure is damaged, the anti-ballistic penetration performance brought by the structure decreases. Therefore, when resisting multiple ballistic penetrations, the advantage of the 8-directional structure is no longer obvious.

[0053] Meanwhile, the average BFS of the orthogonal 8-way structure is slightly better than that of the helical 8-way structure. When using helical layup, the fifth bullet is penetrated during the penetration process, so helical layup may have structural defects. This may be because the interlayer angle in the helical layup sequence is only 22.5°, resulting in insufficient internal friction (binding effect) between adjacent fibers in each layer of UD fabric. When the bullet hits the target plate, the weak binding effect causes the fibers to be directly squeezed apart by the bullet. At the same time, the internal friction provided by the non-directly contacting stressed fibers is insufficient, resulting in the target plate being penetrated. When the interlayer angle is 90°, i.e., orthogonal layup, the binding effect provided by a single fiber to the adjacent fibers can act on the most adjacent fibers. Therefore, the ballistic protection performance of the orthogonal 8-way structure is optimal.

[0054] Comparing Example 2 and Comparative Example 1, it can be seen that in the orthogonal 8-way structure, the manual unidirectional tape laying method, compared with the traditional cutting method, reduces the back concavity depth caused by the first bullet impact by about 27.5%, and the average back concavity depth after six bullet impacts by about 8.5%. This indicates that using unidirectional tape to lay the 8-way UD structure can not only improve the utilization rate of raw materials and reduce production costs, but also further reduce non-penetrating ballistic penetration damage and improve the ballistic resistance of the material. This may be because the smallest unit of UD fabric lamination is a single layer of UD sheet, and the ballistic resistance depends on the structure and integrity of the sheet. As the number of impacts increases, the ballistic resistance decreases significantly after the structure is damaged. However, the smallest unit of unidirectional tape laying is a single unidirectional tape, and the internal structure of the board is relatively "loose" and lacks the structure and integrity of the UD sheet. Therefore, when the structure is damaged, the decrease in ballistic resistance is not obvious.

[0055] Example 4

[0056] A method for preparing a UD-structured multidirectional lay-up bulletproof and impact-resistant composite material is disclosed. The fiber and the UD sheet structure are the same as in Example 2, except for the lay-up step. The preparation steps are as follows:

[0057] Step 1, as follows Figure 3 As shown, a single-layer UD sheet was prepared: using a continuous fiber 3D printer as the layup equipment, high-performance unidirectional fiber fabric that had already achieved mass production was cut into unidirectional strips of equal width along the axial direction as raw material. The width calculation method was the same as in Examples 1-3. Figure 5 The unidirectional tape printhead shown performs tape laying. The unidirectional fiber tape enters the printhead through the feed inlet 1, is held by three pairs of counter-rotating rollers 3, 4, and 6 inside the printhead, and is then pushed out of the printhead. It is then printed onto the pre-applied printing platform 8 via the front pressure roller 7. After printing one unidirectional tape, the built-in scissors 4 cut the fiber unidirectional tape. A robotic arm then moves the printhead to print a second unidirectional tape. The motor precisely controls the printhead position to ensure the second unidirectional tape is tightly aligned with the first, eliminating gaps between the tapes. This process is repeated until laying is complete. Figure 8 The method shown is used for cutting, where the fiber UD sheet with length and width of ab and fiber axis rotation angle of θ is obtained by cutting several unidirectional fiber strips of different lengths and widths of h that are tightly arranged in the axial direction of θ. Compared with using a whole piece of unidirectional fabric with side length αβ for laying, the material waste rate is greatly reduced, and then each single layer of UD sheet with different fiber axis orientation is prepared.

[0058] Step two is the same as in Example 2, and finally a UD structure multi-directionally laid bulletproof and impact-resistant composite material is produced.

[0059] Example 5

[0060] A method for preparing a UD-structured multidirectional lay-up bulletproof and impact-resistant composite material is disclosed. The fiber and the UD sheet structure are the same as in Example 2, except for the lay-up step. The preparation steps are as follows:

[0061] Step 1, as follows Figure 4 As shown, a single-layer UD sheet was prepared using a continuous fiber 3D printer as the layup equipment and fiber monofilaments as the raw material. Figure 6The fiber monofilament is laid out using a printing head. After entering the printing head through the feed port 1, the fiber monofilament is clamped and pushed out of the printing head by three pairs of counter-rotating rollers 3, 4 and 6 inside the printing head. Then, it is printed onto the printing platform 8, which has been pre-coated with adhesive, through the front pressure roller 7. After printing one fiber monofilament, the scissors 4 inside the printing head cut the fiber monofilament. Then, the robotic arm moves the printing head to print the second monofilament. The position of the printing head is precisely controlled by the motor to make the second fiber filament closely aligned with the first fiber filament, eliminating gaps between the fibers. This process is repeated until the laying is completed, directly preparing single-layer UD sheets with different fiber axis orientations.

[0062] Unlike the unidirectional tape printing in Example 4, when switching to monofilament printing, only the print head needs to be replaced. After the coating is completed, no further cutting is required, and a single-layer UD sheet at any angle can be obtained. Compared with the method of coating with UD sheet, this method further improves the utilization rate of raw materials.

[0063] Step two is the same as in Examples 1-3, and finally, a UD structure multi-directional lay-up bulletproof and impact-resistant composite material is produced.

[0064] The UD bulletproof and impact-resistant composite materials in Examples 2, 4, and 5 were subjected to performance tests. The indentation depth of the composite materials was tested in accordance with the Level 2 protection requirements of the standard GA141-2010 "Police Bulletproof Vest". A Type 54 7.62mm pistol was used to carry out a fixed-point, uninterrupted six-shot ballistic penetration test on each fiber composite bulletproof plate. The penetration of the bulletproof target plate and the back indentation depth (BFS) were recorded.

[0065] The data comparison results are shown in Table 2:

[0066]

[0067] Comparing Examples 4 and 2, it can be seen that the composite material with unidirectional tape printing layup has a lower BFS value than that with manual unidirectional tape layup. The back indentation depth caused by the first impact is reduced by approximately 12.3%, and the average back indentation depth after six impacts is reduced by approximately 11.5%. This is because the precise positioning of the print head during unidirectional tape printing layup eliminates more gaps between the unidirectional tapes, reduces structural defects in the composite material, and decreases the probability of rapid material failure during impact. In addition to improving production efficiency, unidirectional tape printing layup can further reduce non-penetrating ballistic damage, making it highly valuable for application.

[0068] Comparing Examples 5 and 4, it can be seen that the composite material with monofilament printing layup has a lower BFS value than that with unidirectional tape printing layup. The indentation depth caused by the first bullet impact decreases by about 6.5%, and the average indentation depth after six bullet impacts decreases by about 10.5%. This is because the fibers in the sheet are tightly arranged, and the binding effect of the fibers directly in contact with the bullet during the impact process is strong. At the same time, the internal friction force provided by the non-directly contacting force-bearing fibers is increased, which means that the bullet has to overcome a stronger force to penetrate the target plate. Therefore, monofilament printing layup further reduces the material waste rate while improving the ballistic performance.

[0069] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A UD structure multi-directional lay-up bulletproof and impact-resistant composite material, which is composed of multiple layers of UD sheets with different fiber rotation angles bonded, stacked and hot-pressed.

2. The UD structure multi-directional lay-up bulletproof and impact-resistant composite material according to claim 1, characterized in that, The distribution of the fiber axis deflection angle of a UD sheet is spiral, that is, the UD fabric is cyclically laid from bottom to top (layer A to layer F) in the order of 0° / 22.5° / 45° / 67.5° / 90° / 112.5° / 135° / 157.5° of the fiber axis direction, wherein the fiber axis deflection between any two adjacent layers of sheet differs by 22.5°.

3. The UD structure multi-directional plywood bulletproof and impact-resistant composite material according to claim 1, characterized in that, The distribution of fiber axis deflection angles in a UD sheet is orthogonal, that is, the UD fabric is cyclically laid from bottom to top (layer A to layer F) in the order of 0° / 90° / 22.5° / 112.5° / 45° / 135° / 67.5° / 157.5° along the fiber axis direction. The fiber deflection angles of the odd-numbered layers of sheets differ by 22.5°, the fiber deflection angles of the even-numbered layers of sheets differ by 22.5°, and the difference between the upper odd-numbered layer and the lower even-numbered layer between adjacent layers is 90°.

4. The UD structure multi-directional lay-up bulletproof and impact-resistant composite material according to claim 1, characterized in that, The number of UD fabric layers is 8. With this number of layers, the back concave shape of the composite material under ballistic penetration changes from a cross shape to a circle, reaching the maximum proportion of deformable fiber area. At this time, the in-plane mechanical properties approach the degree of isotropy (isotropy) of 99.98%. On this basis, the effect of increasing the number of fiber axes on isotropy is negligible. Therefore, 8 axes are determined to be the optimal number of fiber axes for multi-directional UD structure.

5. A preparation method for preparing the aforementioned UD structure multi-directional lay-up bulletproof and impact-resistant composite material, comprising the following steps: Step 1: Preparing single-layer UD sheets using unidirectional tape or fiber monofilaments as raw materials, and laying the raw materials into single-layer UD sheets of a certain size according to a certain orientation angle using a lay-up device. Step 2: Stacking the single-layer UD sheets with different fiber axis orientations prepared in the above steps layer by layer, placing them in an impregnation tank for impregnation and film coating, and then hot-pressing them. The adhesive layer is selected as epoxy resin film with a peel strength greater than 1 N / mm, accounting for 10-20% of the mass percentage of the bulletproof material. The hot-pressing temperature is set to 130±2℃, the pressure is set to 16 MPa, and the temperature and pressure are maintained for 1 hour. After that, the press is turned off, and the material is cooled to room temperature for 30-60 minutes to obtain the UD structure multi-directional lay-up bulletproof and impact-resistant composite material.

6. The UD structure multi-directional lay-up bulletproof and impact-resistant composite material according to claim 1, characterized in that, It should be noted that the present invention can use various feasible thermosetting resin adhesive materials, including polyurethane film, PE film, SEBS hot melt adhesive, etc. The present invention does not limit the specific type of thermosetting resin adhesive used.

7. The preparation method according to claim 5, characterized in that, When using unidirectional tape for layup, the width of the unidirectional tape can be determined based on the required sheet size and layup angle. Assuming the long side of the UD sheet prepared by unidirectional tape layup is *a*, the short side is *b*, the unidirectional tape rotation angle is *θ*, and the unidirectional tape width is *h*, the unidirectional tape width can be obtained from the layup geometry as follows:

8. The preparation method according to claim 5, characterized in that, When using unidirectional tape layup, multiple unidirectional tapes with predetermined widths and layup angles are arranged closely on a plane to form a single-layer fiber UD sheet. However, when using the traditional cutting method for layup, a single layer of unidirectional fabric forms a single-layer fiber UD sheet. The width of the unidirectional fabric required for layup along the diagonal of the sheet is much greater than the width required for layup along the parallel side. Since the width of unidirectional fabric is constant and limited during industrial production, the width of the unidirectional fabric may not meet the size requirements of the fabrication, resulting in a limited layup angle. Unidirectional tape layup overcomes the width limitation by splicing multiple unidirectional tapes, further increasing the size of the sheet that can be prepared by multidirectional layup, and realizing layup with arbitrary width and angle.

9. The preparation method according to claim 5, characterized in that, A continuous fiber 3D printer can be used as a layup device to cut high-performance fiber unidirectional fabric that has been mass-produced into unidirectional strips of equal width along the axial direction. High-precision layup is then performed to eliminate gaps between the unidirectional strips, so that the unidirectional strips are printed tightly arranged on the plane, ultimately forming single-layer fiber UD sheets with different axes.

10. The preparation method according to claim 5, characterized in that, A continuous fiber 3D printer can be used as a layup device to print the fiber monofilaments tightly arranged on a plane, and high-precision layup can eliminate the gaps between the monofilaments, ultimately forming a single-layer fiber UD sheet with different axes.

11. The preparation method according to claim 5, characterized in that, Print size depends on printer size.

12. The preparation method according to claim 5, characterized in that, When the surfacing equipment is a continuous fiber 3D printer, two different surfacing methods can be achieved by changing the print head.

13. The preparation method according to claim 5, characterized in that, When using a unidirectional tape printhead for tape laying, the unidirectional fiber tape enters the printhead through the feed port 1, is clamped by the three pairs of counter-rotating rollers 3, 4 and 6 inside the printhead, and is pushed out of the printhead. Then, it is printed onto the pre-applied printing platform 8 through the front pressure roller 7. After printing one unidirectional tape, the scissors 4 inside the printhead will cut the unidirectional fiber tape. Then, the robotic arm moves the printhead to print the second unidirectional tape. The position of the printhead is precisely controlled by the motor to make the second unidirectional tape closely aligned with the first unidirectional tape, eliminating the gaps between the unidirectional tapes. This process is repeated until the laying is completed and then cut to obtain a single-layer fiber UD sheet.

14. The preparation method according to claim 5, characterized in that, When using a monofilament printhead for individual fiber lay-up, the fiber monofilament enters the printhead through the feed port 1, is held by the three pairs of counter-rotating rollers 3, 4 and 6 inside the printhead, and is pushed out of the printhead. Then, it is printed onto the pre-laid printing platform through the front pressure roller 7. After printing one fiber, the built-in scissors in the printhead cut the fiber monofilament, and then the robotic arm moves the printhead to print the second fiber. The position of the printhead is precisely controlled by the motor to make the second fiber filament closely aligned with the first fiber filament, eliminating gaps between the fibers. This process is repeated until the single-layer fiber UD sheet is printed.

15. The preparation method according to claim 5, characterized in that, In the above technical solution, when using a unidirectional tape to lay high-performance fiber UD sheets as printing material, it is only necessary to cut off the excess material with serrated edges after the laying is completed to obtain a single-layer UD sheet at any angle. Compared with the traditional method of directly using finished UD sheets for laying, this method greatly improves the utilization rate of raw materials, reduces production costs, and is suitable for large-scale industrial production.

16. The preparation method according to claim 5, characterized in that, When using fiber monofilaments to lay high-performance fiber UD sheets as printing materials, no further cutting is required after laying, and a single-layer UD sheet at any angle can be obtained. Compared with the method of laying UD sheets, this method further improves the utilization rate of raw materials.

17. The preparation method according to claim 5, characterized in that, The paving equipment can also be other equipment such as robotic arms or manual paving.

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