Lightweight wave-absorbing bulletproof integrated composite sandwich structure and preparation method thereof

Abstract

The application discloses a kind of lightweight, wave-absorbing, bulletproof integrated sandwich composite armor structure and preparation method thereof, belong to the field of military armored material.The structure includes wave-transparent support bullet-resistant, gradient wave-absorbing, interlayer connection, core bullet-resistant, buffer support and inner layer support unit along the thickness direction: wave-transparent support bullet-resistant unit transmits electromagnetic wave, supports structure, and plays the function of initial bullet-resistant, including the alignment aramid fiber reinforced polymer composite laminated plate of surface layer, alignment aramid fiber reinforced polymer composite sinusoidal wave structure;Inner layer support unit uses carbon fiber reinforced polymer composite laminated plate, and plays the function of support and transition connection;The preparation method uses segmented integration process, inner layer high temperature "foaming+solidification", outer layer ≤70 DEG C, low temperature composite.The armor surface density of the application is 90~110 kg / m², and broadband wave-absorbing, high-efficiency bullet-resistant and lightweight are considered, and it is suitable for military armored vehicles such as step tank, self-propelled artillery, riot armored vehicle etc..

Description

Technical Field

[0001] This invention relates to the field of armor protection equipment technology, specifically to a lightweight, wave-absorbing, and ballistic-resistant integrated sandwich composite armor structure and its preparation method. Background Technology

[0002] In modern military confrontation, the rapid development of radar detection technology and ammunition performance has placed dual stringent requirements on the stealth and protection performance of military armored vehicles: on the one hand, they need to avoid radar detection (radar absorption performance), and on the other hand, they need to resist ammunition attacks (ballistic resistance performance). The synergy between the two has become the core challenge in equipment design.

[0003] Existing technologies have two major problems:

[0004] Traditional radar absorbing materials have limited functionality: taking coating-type radar absorbing materials as an example, they absorb radar waves in a specific frequency band through a single absorption mechanism. The absorption frequency band is usually narrow (mostly concentrated in a certain frequency band between 8-12 GHz), which cannot cover the absorption requirements of wide-range broadband detection. Moreover, these materials have almost no other functional characteristics, including ballistic resistance. The coating is easily damaged after being impacted by ammunition, making it difficult to adapt to the complex electromagnetic environment of the battlefield.

[0005] Traditional ballistic materials are lightweight and lack radar absorption properties: Metal armor (such as steel armor and titanium alloy armor) relies on high hardness and large thickness to resist projectile impact, but its high density (for example, steel armor is about 7.8 g / cm³) greatly increases the weight of equipment and reduces mobility; at the same time, metal materials strongly reflect electromagnetic waves and are easily detected by radar, which cannot meet the requirements of stealth.

[0006] Industry trends indicate that developing an integrated "wave absorption-ballistic resistance" structure is a key approach to resolving the aforementioned contradictions. By integrating wave absorption and ballistic resistance into the same material structure, the thickness redundancy and weight increase caused by single-performance design can be avoided, achieving a balance between stealth, protection, and lightweighting, which is of great significance for upgrading armored vehicles. However, existing integrated solutions may suffer from drawbacks such as narrow wave absorption frequency bands, low ballistic resistance levels, insufficient lightweighting, poor oblique incidence effect, cumbersome and complex molding processes, and high costs, and a mature and reliable technical system has not yet been formed. Summary of the Invention

[0007] The purpose of this invention is to provide a lightweight, wave-absorbing, and ballistic-resistant sandwich composite armor structure and its preparation method, so as to solve the defects of most existing coating-type wave-absorbing materials, which have narrow frequency bands and no ballistic resistance, while ballistic-resistant materials are heavy and have no wave-absorbing properties.

[0008] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0009] A lightweight, wave-absorbing, and ballistic-resistant integrated sandwich composite armor structure comprises, along its thickness, a wave-transparent support ballistic-resistant unit, a gradient wave-absorbing unit, a core ballistic-resistant unit, a buffer support unit, and an inner support unit. The wave-transparent support ballistic-resistant unit is used to initially weaken the projectile's kinetic energy, change its trajectory, resist projectile / fragment impact, and provide electromagnetic wave transmission and structural support. The gradient wave-absorbing unit is used to absorb electromagnetic waves over a wide frequency band, with the absorbent content increasing along the electromagnetic wave incident direction. The core ballistic-resistant unit is used to absorb the projectile's main kinetic energy, prevent projectile penetration, and resist projectile / fragment damage. The buffer support unit is used to absorb residual impact energy and resist residual fragments and ceramic shards.

[0010] Further embodiment: The wave-transparent support ballistic unit includes an outer wave-transparent ballistic layer, a first inner wave-transparent ballistic layer, and a second inner wave-transparent ballistic layer; the outer wave-transparent ballistic layer is an aramid fiber reinforced epoxy resin matrix composite material (AFRP) with a thickness of 1.8-2.2 mm, and the first and second inner wave-transparent ballistic layers are sinusoidal corrugated structures made of AFRP material; the peak height of the sinusoidal corrugated structure is 3.8-4.2 mm, and the corrugated wall thickness is 4.8-5.2 mm.

[0011] Further embodiment: The gradient absorbing unit comprises three layers of absorbing polymethacrylimide (PMI) foam, namely a first absorbing PMI foam layer, a second absorbing PMI foam layer, and a third absorbing PMI foam layer, wherein the absorber mass fractions of the first absorbing PMI foam layer, the second absorbing PMI foam layer, and the third absorbing PMI foam layer are 0.8-1.2 wt%, 1.8-2.2 wt%, and 3.8-4.2 wt%, respectively; the absorber of the absorbing PMI foam is one or more of superconducting carbon black, single-layer graphene, and multi-walled carbon nanotubes.

[0012] Further proposed solution: The adjacent first inner wave-transparent bulletproof layer and second inner wave-transparent bulletproof layer are laid in an orthogonal configuration.

[0013] Further embodiment: The core ballistic unit includes a core ballistic layer and an auxiliary ballistic layer; the core ballistic layer is a boron carbide (B4C) ceramic sheet plate structure with a thickness of 20-22 mm; the auxiliary ballistic layer is a titanium alloy (Ti-6Al-4V) layer plate structure with a thickness of 2-2.5 mm.

[0014] Further embodiment: The interlayer connection unit includes three quartz fiber reinforced polymer composite (QFRP) square tubes, namely the first interlayer connection layer, the second interlayer connection layer, and the third interlayer connection layer, used to connect and support the wave-transparent and ballistic-resistant unit and the gradient wave-absorbing unit; the outer wave-transparent and ballistic-resistant layer is connected to the first inner wave-transparent and ballistic-resistant layer by the first interlayer connection layer, the first inner wave-transparent and ballistic-resistant layer and the second inner wave-transparent and ballistic-resistant layer are connected by the second interlayer connection layer, and the second inner wave-transparent and ballistic-resistant layer and the core ballistic-resistant layer are both connected by the third interlayer connection layer; the QFRP tube has a square cross-section with a side length of 5-6 mm and a wall thickness of 0.6-0.8 mm.

[0015] Further embodiment: The core ballistic protection unit includes a core ballistic protection layer and an auxiliary ballistic protection layer; the core ballistic protection layer is a B4C ceramic sheet with a thickness of 20-22 mm; the auxiliary ballistic protection layer is a titanium alloy layer with a thickness of 2.0-2.5 mm.

[0016] Further solution: The buffer support unit is UHMWPF non-woven fabric, which is laid in an alternating 0-90° orthogonal pattern with a thickness of 5-6 mm.

[0017] Further option: The inner support layer is a carbon fiber reinforced epoxy resin matrix composite (CFRP) with a thickness of 0.8-1.2 mm.

[0018] Further solution: The sinusoidal corrugated structures of adjacent inner wave-transparent and ballistic-resistant layers are laid orthogonally.

[0019] Further proposed solution: The interlayer connection units used have the following height distances after insertion: The first interlayer connection layer satisfies the minimum planar distance between the outer wave-transparent ballistic layer and the first inner wave-transparent ballistic layer being 1.8-2.2 mm; the second interlayer connection layer satisfies the minimum planar distance between the first inner wave-transparent ballistic layer and the second inner wave-transparent ballistic layer being 1.8-2.2 mm; the third interlayer connection layer satisfies the minimum planar distance between the second inner wave-transparent ballistic layer and the core ballistic layer being 9.8-10.2 mm.

[0020] Further proposed solution: The surface density of the sandwich composite armor structure is 90~110 kg / m², and the overall thickness is ≤75mm; it can effectively absorb electromagnetic microwaves with a reflectivity of ≥90% in the 4-40 GHz full frequency band, effectively resist the penetration of the Type 54 12.7 mm armor-piercing incendiary projectile, and the secondary fragmentation rate is ≤10%.

[0021] A method for preparing a lightweight, wave-absorbing, and ballistic-resistant integrated sandwich composite armor structure includes the following steps:

[0022] S1: Prepare microwave absorbing PMI foam boards with different absorbent contents. The surface coating technology is used to prepare the foam by mixing and foaming pre-prepared expandable PMI particles with microwave absorbing slurry in a specific ratio. By adjusting the absorbent content, microwave absorbing PMI foam boards with different absorbent contents can be obtained. The specific method can refer to the preparation method of a lightweight, broadband microwave-absorbing PMI foam sandwich composite material microwave-absorbing structure in patent number CN117621580A; prepare the first inner wave-transparent and elastic-resistant layer and the second inner wave-transparent and elastic-resistant layer by molding process, and the preparation method can refer to the preparation technology in the literature: "UHMWPE Composite Corrugated Board Structure Design and Mechanical Property Research"; make square grooves with a depth of 0.9-1.1 mm on the upper and lower sides of the center of the prepared first inner wave-transparent and elastic-resistant layer and the second inner wave-transparent and elastic-resistant layer respectively; cut the prepared microwave-absorbing PMI foam board into the corresponding corrugated shape and size according to the corresponding requirements, and similarly make square grooves with a depth of 0.9-1.1 mm on the upper and lower sides of the center of the first microwave-absorbing PMI foam layer, the second microwave-absorbing PMI foam layer and the third microwave-absorbing PMI foam layer respectively. Interlayer connection units that meet dimensional requirements are prepared using a molding process, and then connected by inserting the interlayer connection units into slots. After connection, the minimum planar distance between the upper wave peak of the outer wave-transparent ballistic layer and the first inner wave-transparent ballistic layer is measured to be 1.8-2.2 mm, the minimum planar distance between the lower wave peak of the first inner wave-transparent ballistic layer and the upper wave peak of the second inner wave-transparent ballistic layer is 1.8-2.2 mm, and the minimum planar distance between the lower wave peak of the second inner wave-transparent ballistic layer and the core ballistic layer is 9.8-10.2 mm.

[0023] S2: First, lay the core ballistic layer into the mold. Then, lay a microwave-absorbing PMI foam board with a mass fraction of 3.8-4.2 wt% on top of the core ballistic layer. The thickness of the 3.8-4.2 wt% microwave-absorbing PMI foam board should be 4.8-5.2 mm. Insert the second inner layer of wave-transparent ballistic layer, with the interlayer connecting layer inserted at its lower center, into the mold, ensuring the interlayer connecting layer is placed vertically on the foam board. The corrugated cell pores on the lower side of the second inner layer of wave-transparent ballistic layer correspond to the microwave-absorbing PMI foam board with a mass fraction of 3.8-4.2 wt% cut according to its corresponding morphology, ensuring the second inner layer of wave-transparent ballistic layer is horizontal. Insert the interlayer connecting layer into the central groove on the upper side of the second inner layer of wave-transparent ballistic layer. The corrugated cell pores on the upper side correspond to the microwave-absorbing PMI foam board with a mass fraction of 1.8-2.2 wt% cut according to its corresponding morphology. wt% of wave-absorbing PMI foam boards are correspondingly laid out and embedded in the corrugated structure, with a total mass of 74-76% of the total mass of foam boards laid on the core ballistic layer. The first inner wave-transparent ballistic layer is laid into the mold, with its lower center connected to the upper interlayer connecting layer of the second inner wave-transparent ballistic layer via a slot. The first inner wave-transparent ballistic layer is placed horizontally, maintaining an orthogonal position to the second inner wave-transparent ballistic layer. An interlayer connecting layer is inserted into the upper center of the inner wave-transparent ballistic layer, ensuring it remains vertical. The upper corrugated cell pores are cut according to their corresponding morphology, with a mass fraction of 0.8-1.2. The wt% of wave-absorbing PMI foam boards correspond to each other, so that the foam boards are evenly laid and embedded in the corrugated structure, with a total mass of 48~52% of the total mass of the foam boards laid on the core ballistic layer; the outer wave-transparent ballistic layer is embedded in the mold, placed on the upper side of the interlayer connecting layer, kept horizontal, and then the mold is closed and "cured" at high temperature; the mold size is closely assembled with the composite armor structure.

[0024] S3: The auxiliary anti-ballistic layer of the core anti-ballistic unit, the buffer support unit and the inner support unit are laid sequentially on the outside of the integrated inner structure. Low-temperature curing epoxy film is set between the layers. After low-temperature curing, a sandwich composite armor structure is obtained.

[0025] As a further embodiment of the present invention: the temperature of the high-temperature "foaming" in step S1 is 180-190 ℃, and the heat preservation time is 4-5 h.

[0026] As a further embodiment of the present invention: the temperature of the high-temperature "curing" in step S2 is ≤150 ℃, and the heat preservation time is 1-2 h.

[0027] As a further embodiment of the present invention: the temperature of low-temperature curing in step S3 is ≤70 ℃, and the heat preservation time is 5-6 h.

[0028] The present invention has the following beneficial effects:

[0029] Excellent wideband absorption performance: The large thickness of the gradient absorbing unit, the "low → medium → high" absorber distribution, and the orthogonal sinusoidal corrugated structure can effectively absorb electromagnetic waves in the full-band range of 4-40 GHz, with an electromagnetic wave absorption rate of ≥90%, and fully cover the mainstream detection frequency bands of military radar.

[0030] Strong ballistic protection:

[0031] Ballistic resistance rating: Can withstand the penetration of Type 54 12.7mm armor-piercing incendiary rounds;

[0032] Secondary damage control: The synergistic effect of "boron carbide ceramic + titanium alloy + UHMWPF non-woven fabric" reduces the secondary fragmentation rate to less than 10%, eliminating the hidden danger of fragmentation from ceramic armor.

[0033] Significant advantages of lightweight design: The designed composite armor structure has a surface density of 90-110 kg / m², which is only equivalent to the surface density of armor steel with a thickness of 1.2-1.4 cm, but its ballistic protection performance exceeds that of armor steel with a surface density of 50 mm.

[0034] High structural stability: The segmented integrated molding process ensures no delamination between layers, low-temperature curing protects the performance of sensitive materials, and there is no performance degradation during long-term use (-50℃ to 80℃), making it suitable for complex battlefield environments. Attached Figure Description

[0035] Figure 1 A layered schematic diagram of the lightweight, wave-absorbing, and ballistic-resistant integrated sandwich composite armor structure of this invention;

[0036] Figure 2 Cross-sectional view of sandwich composite armor structure.

[0037] Figure 3 Schematic diagram of the orthogonal sinusoidal corrugated structure of the inner anti-elastic wave-absorbing layer.

[0038] Figure 4 : Exploded view of each layer of the present invention.

[0039] Explanation of reference numerals in the attached diagram: 1-Outer wave-transparent ballistic layer, 2-First wave-absorbing PMI foam layer, 3-First inner wave-transparent ballistic layer, 4-Second wave-absorbing PMI foam layer, 5-Second inner wave-transparent ballistic layer, 6-Third wave-absorbing PMI foam layer, 7-Core ballistic layer, 8-Auxiliary ballistic layer, 9-Buffer support unit, 10-Inner support unit, 11-First interlayer connection layer, 12-Second interlayer connection layer, 13-Third interlayer connection layer. Detailed Implementation

[0040] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0041] Example 1 (Standard Specification Composite Armor)

[0042] Raw material preparation

[0043] Wave-transparent support ballistic unit: AFRP laminate (thickness 2 mm, 1.4 g / cm³), AFRP sinusoidal corrugated plate structure (wave crest 4 mm, thickness 5 mm, half-cycle length 5 mm, 1.4 g / cm³), the AFRP sinusoidal corrugated structure has square slots at the top and bottom of the center to match the interlayer connection unit, and the slot depth is 1 mm.

[0044] Gradient absorbing units: 1 wt% absorbing PMI foam board, 2 wt% absorbing PMI foam board, 4 wt% absorbing PMI foam board;

[0045] Interlayer connection unit: three QFRP hollow square tubes (section side length 5 mm, wall thickness 0.6 mm), the height of which meets the following requirements: after connection, the minimum planar distance between the outer wave-transparent bulletproof layer and the adjacent inner wave-transparent bulletproof layer is 2 mm, the minimum planar distance between the two inner wave-transparent bulletproof layers is 2 mm, and the minimum planar distance between the core bulletproof layer and the adjacent inner wave-transparent bulletproof layer is 10 mm.

[0046] Core ballistic protection unit: B4C ceramic plate (20 mm thick, 2.5 g / cm³), Ti-6Al-4V plate (2 mm thick, 4.5 g / cm³).

[0047] Buffer support unit: orthogonally laid UHMWPF non-woven fabric (5 mm thick, 0.97 g / cm³).

[0048] Auxiliary materials: Low-temperature high-strength curing epoxy film (curing temperature ≤70 ℃), and molds for tight assembly.

[0049] Preparation steps

[0050] Fabrication of integrated inner layer structure:

[0051] The following steps are applied to the mold: B4C ceramic flat plate → 4 wt% PMI foam board (flat, 5 mm thick) → QFRP square tube + AFRP sinusoidal corrugated structure → 2 wt% PMI foam board (evenly laid in the gaps between corrugated cells, 75% of the mass of 4 wt% PMI foam board) → QFRP square tube + AFRP sinusoidal corrugated structure (sinusoidal laying) → QFRP square tube → 1 wt% PMI foam board (evenly laid in the gaps between corrugated cells, 50% of the mass of 4 wt% PMI foam board) → AFRP laminate.

[0052] The integrated inner layer structure (layers 1-7 and 11-13) was removed after being cured at 150 ℃ for 2 hours and cooled.

[0053] Preparation of the integral composite structure:

[0054] The inner structure consists of: laying a film on the lower surface of the 7th layer → stacking a Ti-6Al-4V flat plate → laying a film → stacking a UHMWPF non-woven fabric (0-90° orthogonal laying) → laying a film → stacking a CFRP laminate;

[0055] The core composite armor structure was cured at 65 ℃ for 4.5 h and the edges were polished to obtain an overall thickness of 70 mm and a surface density of 90 kg / m².

[0056] Proportional Design

[0057] Comparative Example 1 (Traditional Steel Armor): Made of Q235 steel, 20mm thick, with a surface density of 156kg / m²;

[0058] Comparative Example 2 (Single Absorbing Material): Ferrite-based coated absorbing material (3 mm thick) + aluminum alloy substrate (20 mm thick) + boron carbide ceramic (10 mm) was used, with an overall density of 102.4 kg / m².

[0059] Simulation:

[0060] Simulations of the wave absorption and ballistic resistance performance of Example 1 were performed and compared with those of Comparative Examples 1 and 2. The results are shown in the table below:

[0061] Simulation test results show that Example 1 is significantly better than the comparative example in terms of absorption bandwidth, ballistic resistance, lightweighting, and secondary damage control, verifying the effectiveness of the technical solution of the present invention.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A lightweight, wave-absorbing, and ballistic-resistant sandwich composite armor structure, characterized in that, Along the thickness direction, it includes, in sequence, a wave-transparent support ballistic unit, a gradient wave-absorbing unit, an interlayer connection unit, a core ballistic unit, a buffer support unit (9), and an inner support unit (10). The wave-transmitting support anti-ballistic unit is used to initially weaken the kinetic energy of the projectile, change the trajectory direction, resist the impact of projectiles / fragments, and provide the functions of transmitting electromagnetic waves and structural support. The gradient absorbing unit is used for broadband absorption of electromagnetic microwaves, and the mass fraction of the absorber along the incident direction of the electromagnetic wave is distributed in an increasing manner. The interlayer connection unit is used to support the structure, improve the mechanical performance of the structure, and connect the wave-transparent support and anti-elasticity unit with the gradient wave-absorbing unit. The core anti-ballistic unit is used to absorb the main kinetic energy of the projectile, prevent the projectile from penetrating, and resist the killing effect of projectiles / fragments; The buffer support unit (9) is used to absorb residual impact energy, prevent ceramic fragments from splashing, and resist residual shrapnel. The inner support unit (10) is used to support the structure and connect the outer armor and the internal space to achieve a transition function.

2. The lightweight, wave-absorbing, and ballistic-resistant integrated sandwich composite armor structure according to claim 1, characterized in that, The wave-transparent support ballistic unit includes an outer wave-transparent ballistic layer (1), a first inner wave-transparent ballistic layer (3), and a second inner wave-transparent ballistic layer (5). The outer wave-transparent ballistic layer (1) is an epoxy resin-based composite material (AFRP) reinforced with para-aramid fibers, with a thickness of 1.8-2.2 mm. The first inner wave-transparent ballistic layer (3) and the second inner wave-transparent ballistic layer (5) are sinusoidal corrugated structures made of AFRP material. The peak height of the sinusoidal corrugated structure is 3.8-4.2 mm, and the corrugated wall thickness is 4.8-5.2 mm.

3. The lightweight, wave-absorbing, and ballistic-resistant integrated sandwich composite armor structure according to claim 1, characterized in that, The gradient absorbing unit comprises three layers of absorbing polymethacrylimide (PMI) foam, namely a first absorbing PMI foam layer (2), a second absorbing PMI foam layer (4), and a third absorbing PMI foam layer (6). The absorber mass fractions of the first absorbing PMI foam layer (2), the second absorbing PMI foam layer (4), and the third absorbing PMI foam layer (6) are 0.8-1.2 wt%, 1.8-2.2 wt%, and 3.8-4.2 wt%, respectively. The absorber of the absorbing PMI foam is one or more of superconducting carbon black, single-layer graphene, and multi-walled carbon nanotubes.

4. The lightweight, wave-absorbing, and ballistic-resistant integrated sandwich composite armor structure according to claim 2, characterized in that, The adjacent first inner wave-transparent ballistic layer (3) and second inner wave-transparent ballistic layer (5) are laid in an orthogonal manner.

5. The lightweight, wave-absorbing, and ballistic-resistant integrated sandwich composite armor structure according to claim 1, characterized in that, The core ballistic unit includes a core ballistic layer (7) and an auxiliary ballistic layer (8); the core ballistic layer (7) is a boron carbide (B4C) ceramic sheet flat structure with a thickness of 20-22 mm; the auxiliary ballistic layer (8) is a titanium alloy (Ti-6Al-4V) layer flat structure with a thickness of 2-2.5 mm.

6. The lightweight, wave-absorbing, and ballistic-resistant integrated sandwich composite armor structure according to claim 1, characterized in that, The interlayer connection unit includes three quartz fiber reinforced polymer composite (QFRP) square tubes, namely the first interlayer connection layer (11), the second interlayer connection layer (12), and the third interlayer connection layer (13), which are used to connect and support the wave-transparent and ballistic-resistant unit and the gradient wave-absorbing unit. The outer wave-transparent and ballistic-resistant layer (1) is connected to the first inner wave-transparent and ballistic-resistant layer (3) by the first interlayer connection layer (11), the first inner wave-transparent and ballistic-resistant layer (3) is connected to the second inner wave-transparent and ballistic-resistant layer (5) by the second interlayer connection layer (12), and the second inner wave-transparent and ballistic-resistant layer (5) is connected to the core ballistic-resistant layer (7) by the third interlayer connection layer (13). The QFRP tube has a square cross-section with a side length of 5-6 mm and a wall thickness of 0.6-0.8 mm.

7. The lightweight, wave-absorbing, and ballistic-resistant integrated sandwich composite armor structure according to claim 1, characterized in that, The buffer support unit (9) is a non-woven fabric of ultra-high molecular weight polyethylene fiber (UHMWPF), and its layers are laid in alternating orthogonal patterns of 0-90° with a thickness of 5-6 mm. The inner support layer (10) is a carbon fiber reinforced epoxy resin matrix composite (CFRP) with a thickness of 0.8-1.2 mm.

8. The lightweight, wave-absorbing, and ballistic-resistant integrated sandwich composite armor structure according to claim 1, characterized in that, The composite armor structure has an areal density of 90~110 kg / m² and an overall thickness of ≤ 75 mm; it can achieve effective electromagnetic microwave absorption with an absorption rate of ≥90% across the entire frequency band from 4 to 40 GHz.

9. The lightweight, wave-absorbing, and ballistic-resistant integrated sandwich composite armor structure according to any one of claims 1-8, characterized in that, The height distance of the interlayer connection units used after insertion is as follows: the first interlayer connection layer (11) satisfies that the minimum planar distance between the outer wave-transparent ballistic layer (1) and the first inner wave-transparent ballistic layer (3) is 1.8-2.2 mm; the second interlayer connection layer (12) satisfies that the minimum planar distance between the first inner wave-transparent ballistic layer (3) and the second inner wave-transparent ballistic layer (5) is 1.8-2.2 mm; The third interlayer connecting layer (13) satisfies the minimum planar distance between the second inner wave-transparent ballistic layer (5) and the core ballistic layer (7) being 9.8-10.2 mm.

10. A method for preparing a lightweight, wave-absorbing, and ballistic-resistant integrated sandwich composite armor structure as described in claim 9, characterized in that, Includes the following steps: S1: Prepare microwave-absorbing PMI foam boards with different absorbent contents. Using surface coating technology, these boards are prepared by mixing pre-prepared expandable PMI particles with microwave-absorbing slurry in a specific ratio. By adjusting the absorbent content, microwave-absorbing PMI foam boards with different absorbent contents are obtained. Prepare the first inner wave-transparent and bulletproof layer (3) and the second inner wave-transparent and bulletproof layer (5) using a molding process. Cut square grooves with a depth of 0.9-1.1 mm on the upper and lower sides of the center of the prepared first inner wave-transparent and bulletproof layer (3) and the second inner inner wave-transparent and bulletproof layer (5). Cut the prepared microwave-absorbing PMI foam boards according to the corresponding requirements to create the appropriate corrugated shapes and sizes. Similarly, cut grooves with a depth of 0.9-1.1 mm on the upper and lower sides of the center of the first microwave-absorbing PMI foam layer (2), the second microwave-absorbing PMI foam layer (4), and the third microwave-absorbing PMI foam layer (6). A square slot of mm is used to prepare interlayer connection units that meet the size and shape requirements by molding process, and the interlayer connection units are inserted into the slot for connection; after connection, the minimum planar distance between the upper wave peak of the outer wave-transparent ballistic layer (1) and the first inner wave-transparent ballistic layer (3) is measured to be 1.8-2.2 mm, the minimum planar distance between the lower wave peak of the first inner wave-transparent ballistic layer (3) and the upper wave peak of the second inner wave-transparent ballistic layer (5) is 1.8-2.2 mm, and the minimum planar distance between the lower wave peak of the second inner wave-transparent ballistic layer (5) and the core ballistic layer (7) is 9.8-10.2 mm; S2: First, lay the core ballistic layer (7) into the mold, then lay the wave-absorbing PMI foam board with a mass fraction of 3.8-4.2 wt% on top of the core ballistic layer (7). The thickness of the wave-absorbing PMI foam board with a mass fraction of 3.8-4.2 wt% should be 4.8-5.2 mm. Insert the second inner wave-transparent ballistic layer with the interlayer connecting layer (13) inserted into the lower center into the mold, so that the interlayer connecting layer (13) is placed vertically on the foam board. The corrugated cell pores on the lower side of the second inner wave-transparent ballistic layer (5) correspond to the wave-absorbing PMI foam board with a mass fraction of 3.8-4.2 wt% cut according to its corresponding morphology, ensuring that the second inner wave-transparent ballistic layer (5) is in a horizontal state. Insert the interlayer connecting layer (12) into the center slot on the upper side of the second inner wave-transparent ballistic layer (5). The corrugated cell pores on the upper side correspond to the wave-absorbing PMI foam board with a mass fraction of 1.8-2.2 wt% cut according to its corresponding morphology. The wt% of wave-absorbing PMI foam boards correspond to each other, so that the foam boards are evenly laid and embedded in the corrugated structure, and the total mass is 74~76% of the total mass of the foam boards laid on the core ballistic layer (7); the first inner wave-transparent ballistic layer (3) is laid into the mold, and the lower center of the first inner wave-transparent ballistic layer (3) is connected to the interlayer connection layer (12) on the upper side of the second inner wave-transparent ballistic layer (5) through the slot. The first inner wave-transparent ballistic layer (3) is kept horizontally, and its positional relationship with the second inner wave-transparent ballistic layer (5) is kept orthogonal to each other; the interlayer connection layer (11) is inserted into the upper center of the inner wave-transparent ballistic layer (3), so that the interlayer connection layer (11) is kept vertical. The upper corrugated cell pores are cut according to their corresponding morphology and have a mass fraction of 0.8-1.

2. The wt% of wave-absorbing PMI foam boards correspond to each other, so that the foam boards are evenly laid and embedded in the corrugated structure, and the total mass is 48~52% of the total mass of the foam boards laid on the core ballistic layer (7); the outer wave-transparent ballistic layer (1) is embedded in the mold, placed on the upper side of the interlayer connection layer (11), kept in a horizontal state, and then the mold is closed and "cured" at high temperature; the mold size is closely assembled with the composite armor structure; S3: The auxiliary anti-ballistic layer (8), buffer support unit (9) and inner support unit (10) of the core anti-ballistic unit are laid sequentially on the outside of the integrated inner layer structure. Low-temperature curing epoxy film is set between the layers. After low-temperature curing, a sandwich composite armor structure is obtained. The high-temperature "foaming" in step S1 is performed at a temperature of 180-190 ℃ for 4-5 hours. The high-temperature "curing" temperature in step S2 is 130-150 ℃, and the holding time is 1-2 h; The low-temperature curing temperature in step S3 is 60-70 ℃, and the heat preservation time is 5-6 h.

Images