Modular filled composite honeycomb and method of making and use thereof

Abstract

The application discloses a modular filling combined honeycomb and a preparation method and application thereof, and relates to the technical field of wave-absorbing materials. The modular filling combined honeycomb comprises a plurality of honeycomb holes filled with functional materials, the functional materials in the honeycomb holes are the same or different, and each functional material comprises a foamed material. The modular filling combined honeycomb can be designed in a wave-absorbing structure according to the requirement of a single honeycomb hole, and is helpful to improve the service life and wave-absorbing effect of the honeycomb, widen the application field of the honeycomb, and especially the application in an aviation stealth fighter.

Description

Technical Field

[0001] This application relates to the field of microwave absorbing materials technology, and more specifically, to a modular filled composite honeycomb, its preparation method, and its application. Background Technology

[0002] With the advancement of military radar detection technology, the ability to detect and analyze military aircraft is becoming increasingly stronger. In order to enhance the battlefield environment survivability and adaptability of special aircraft such as fighter jets, bombers, and electromagnetic aircraft, it is necessary to design the aircraft's shape in the early stages of manufacturing to make its surface as smooth, flat, and seamless as possible to generate electromagnetic echoes. At the same time, it is necessary to structurally integrate the parts with high electromagnetic wave reflection with stealth absorbing materials so that the incident electromagnetic waves can enter the stealth structure of the aircraft to the maximum extent. Through the functional and structural characteristics of the materials, the electromagnetic wave energy inside the materials is effectively attenuated, thereby ensuring the safe flight of the aircraft.

[0003] Currently, due to structural mechanics and weight requirements, aircraft structures often employ lightweight, high specific strength and stiffness, strong impact and fatigue resistance, and high design flexibility honeycomb (PMI foam) sandwich structures as stealth materials. Traditional absorbing honeycomb structures have limited performance, and the impregnation and coating processes for absorbing slurry can only be gradual in certain areas. Due to process limitations, the amount of absorbing slurry adhering to different parts of the honeycomb varies, leading to deformation of the honeycomb lattice and resulting in poor structural stability and shear resistance of subsequent honeycomb components. To improve the absorption effect, a complex stacked structure consisting of resistive sheets + honeycomb + resistive sheets + honeycomb is usually constructed along the T-direction of the honeycomb. However, this structure has poor interlayer bonding and is prone to delamination, severely affecting the overall structural strength of the component. Summary of the Invention

[0004] The main objective of this application is to provide a modular filled composite honeycomb structure, its preparation method, and its application, in order to solve the problem that current stealth materials have insufficient structural stability and are difficult to achieve both high wave absorption performance and high mechanical performance.

[0005] To achieve the above objectives, according to a first aspect of this application, a modular filled composite honeycomb is provided, comprising a plurality of honeycomb pores filled with functional materials, wherein the functional materials in each honeycomb pore are the same or different; and each functional material includes a foaming material.

[0006] Furthermore, each functional material independently includes at least one of a first functional layer, a second functional layer, a third functional layer, a fourth functional layer, a fifth functional layer, a sixth functional layer, a seventh functional layer, and an eighth functional layer; when the functional material includes multiple functional layers, the functional layers are stacked along the T-direction of the modular filled composite honeycomb to form the functional material; the thickness of each functional layer is independently 0.05 to 1 times the height of the honeycomb pores.

[0007] Furthermore, the material of the first functional layer is a high-resistivity loss type foam material with a sheet resistance of 50~100 kΩ / □, and its composition does not include hollow microwave absorbing microspheres.

[0008] Furthermore, the material of the second functional layer is a medium-resistance loss type foam material with a sheet resistance of 10~50 kΩ / □, and its composition does not include hollow microwave absorbing microspheres.

[0009] Furthermore, the material of the third functional layer is a low-resistance-loss foam material with a sheet resistance of 5~10 kΩ / □, and its composition does not include hollow microwave absorbing microspheres.

[0010] Furthermore, the material of the fourth functional layer is an ultra-low resistance loss type foam material with a sheet resistance of 1~5 kΩ / □, and its composition does not include hollow microwave absorbing microspheres.

[0011] Furthermore, the fifth functional layer is made of a high magnetic loss foam material with a magnetic permeability of 3~5 H / m;

[0012] Furthermore, the material of the sixth functional layer is a low-resistivity loss type three-dimensional thin-walled hollow microwave absorbing material with a sheet resistance of 5~10 kΩ / □, and its composition includes hollow microwave absorbing microspheres.

[0013] Furthermore, the material of the seventh functional layer is a medium-resistance loss type three-dimensional thin-walled hollow microwave absorbing material with a sheet resistance of 10~50 kΩ / □, and its composition includes hollow microwave absorbing microspheres.

[0014] Furthermore, the material of the eighth functional layer is a high-resistivity loss type three-dimensional thin-walled hollow microwave absorbing material with a sheet resistance of 50~100 kΩ / □, and its composition includes hollow microwave absorbing microspheres.

[0015] Furthermore, along any direction perpendicular to the T-direction of the modular filling composite honeycomb, the following functional materials are sequentially and cyclically filled into each honeycomb cell: first functional material, second functional material, third functional material, fourth functional material, third functional material, and second functional material;

[0016] The first functional material consists of a first functional layer;

[0017] Second functional material: The second functional layer and the first functional layer are stacked sequentially from bottom to top;

[0018] Third functional material: The third functional layer, the second functional layer, and the first functional layer are stacked sequentially from bottom to top;

[0019] Fourth functional material: The third functional layer, the second functional layer, and the first functional layer are stacked sequentially from bottom to top;

[0020] The thickness of the first functional layer is 0.05 to 0.15 times the height of the honeycomb cells, the thickness of the second functional layer is 0.15 to 0.2 times the height of the honeycomb cells, and the thickness of the third functional layer is 0.15 to 0.25 times the height of the honeycomb cells.

[0021] Furthermore, along any direction perpendicular to the T-direction of the modular filled composite honeycomb, the following functional materials are sequentially filled into each honeycomb cell:

[0022] Fifth functional material: The fifth functional layer, the fourth functional layer, and the fifth functional layer are stacked sequentially from bottom to top;

[0023] Fifth functional material;

[0024] Sixth functional material: The fifth functional layer, the third functional layer, and the fifth functional layer are stacked sequentially from bottom to top;

[0025] Seventh functional material: The fifth functional layer, the second functional layer, and the fifth functional layer are stacked sequentially from bottom to top;

[0026] Eighth functional material: The fifth functional layer, the first functional layer, and the fifth functional layer are stacked sequentially from bottom to top;

[0027] The thickness of the first functional layer is 0.7 to 0.9 times the height of the honeycomb cells, the thickness of the second functional layer is 0.7 to 0.9 times the height of the honeycomb cells, the thickness of the third functional layer is 0.7 to 0.9 times the height of the honeycomb cells, the thickness of the fourth functional layer is 0.7 to 0.9 times the height of the honeycomb cells, and the thickness of the fifth functional layer is 0.05 to 0.15 times the height of the honeycomb cells.

[0028] Furthermore, along any direction perpendicular to the T-direction of the modular filled composite honeycomb, the following functional materials are filled into each honeycomb cell:

[0029] Ninth functional material: The fourth functional layer, the third functional layer, the second functional layer, and the first functional layer are stacked sequentially from bottom to top;

[0030] The thickness of the first functional layer is 0.05 to 0.15 times the height of the honeycomb cells, the thickness of the second functional layer is 0.1 to 0.2 times the height of the honeycomb cells, the thickness of the third functional layer is 0.2 to 0.3 times the height of the honeycomb cells, and the thickness of the fourth functional layer is 0.3 to 0.5 times the height of the honeycomb cells.

[0031] Furthermore, along any direction perpendicular to the T-direction of the modular filled composite honeycomb, the following functional materials are filled into each honeycomb cell:

[0032] Tenth functional material: The fourth, sixth, seventh and eighth functional layers are stacked sequentially from bottom to top;

[0033] The thickness of the fourth functional layer is 0.2 to 0.3 times the height of the honeycomb cells, the thickness of the sixth functional layer is 0.2 to 0.4 times the height of the honeycomb cells, the thickness of the seventh functional layer is 0.2 to 0.3 times the height of the honeycomb cells, and the thickness of the eighth functional layer is 0.1 to 0.2 times the height of the honeycomb cells.

[0034] The sixth, seventh, and eighth functional layers each independently include at least one of graded A spheres with a diameter of 1-1.5 mm and graded B spheres with a diameter of 2.2-3 mm. The A and B spheres are only used to distinguish the diameter and do not represent specific types. The A and B spheres can be combined between the sixth, seventh, and eighth functional layers according to the stealth design. For example, the sixth functional layer includes A spheres, the seventh functional layer includes B spheres, etc.

[0035] Furthermore, along any direction perpendicular to the T-direction of the modular filled composite honeycomb, the following functional materials are filled into each honeycomb cell:

[0036] Eleventh functional material: The first functional layer, the second functional layer, the third functional layer, the fourth functional layer, the third functional layer, the second functional layer, and the first functional layer are stacked sequentially from bottom to top;

[0037] The thickness of the first functional layer is 0.05 to 0.1 times the height of the honeycomb cells, the thickness of the second functional layer is 0.1 to 0.15 times the height of the honeycomb cells, the thickness of the third functional layer is 0.1 to 0.15 times the height of the honeycomb cells, and the thickness of the fourth functional layer is 0.2 to 0.4 times the height of the honeycomb cells.

[0038] According to a second aspect of this application, a method for preparing a modularly filled composite honeycomb is provided, comprising the following steps:

[0039] S1. Prepare different types of foamed preforms and thin-walled hollow microwave absorbing preforms to obtain high-resistivity-loss foamed preforms, medium-resistivity-loss foamed preforms, low-resistivity-loss foamed preforms, extremely low-resistivity-loss foamed preforms, high-magnetic-loss foamed preforms, low-resistivity-loss three-dimensional thin-walled hollow microwave absorbing preforms, medium-resistivity-loss three-dimensional thin-walled hollow microwave absorbing preforms, and high-resistivity-loss three-dimensional thin-walled hollow microwave absorbing preforms.

[0040] S2, cut different types of foamed preforms to obtain different cylindrical strips;

[0041] S3, cut different cylindrical strips according to the required thickness to obtain the same or different foamed prefabricated blocks;

[0042] S4. According to the design, foamed prefabricated blocks or foamed prefabricated blocks and thin-walled hollow microwave absorbing prefabricated blocks are stacked from bottom to top in different honeycomb cells of the modular filling combined honeycomb to obtain honeycomb semi-finished products.

[0043] S4. The honeycomb semi-finished product is cured to obtain a modular filling combination honeycomb.

[0044] Among them, the foamed precast block becomes foamed material after curing, and the thin-walled hollow microwave absorbing precast becomes thin-walled hollow microwave absorbing material after curing.

[0045] Furthermore, the diameter of the cylindrical strip is 50% to 80% of the diameter of the honeycomb pores.

[0046] According to a third aspect of this application, an application is provided of a modularly filled composite honeycomb of the first aspect of this application or a modularly filled composite honeycomb prepared by the preparation method of the second aspect of this application in a stealth device.

[0047] The modular filling and combination honeycomb structure of this application allows for the design of individual honeycomb cells, enabling more precise 3D absorbing interface design, improving the absorbing performance of stealth devices, and enhancing their battlefield survivability. Furthermore, compared to absorbing honeycombs produced by traditional impregnation or coating with absorbing slurry, designing individual honeycomb cells and filling them with foam material helps improve their structural stability. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the modular filling combined honeycomb structure in Embodiments 1(A) and 2(B) of this application;

[0049] Figure 2 These are schematic diagrams of the modular filling combined honeycomb structure in Embodiments 3(C), 4(D), and 5(E) of this application;

[0050] Figure 3 This is a schematic diagram of the modular filling combined honeycomb structure in Embodiment 6 of this application;

[0051] The above figures contain the following reference numerals:

[0052] 1. Cellular substrate; 2. First functional layer; 3. Second functional layer; 4. Third functional layer; 5. Fourth functional layer; 6. Fifth functional layer; 7. Sixth functional layer; 8. Seventh functional layer; 9. Eighth functional layer. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0054] As described in the background section of this application, existing technologies suffer from poor stability of absorbing honeycomb structures. To address this technical problem, in a typical embodiment of this application, a modularly filled composite honeycomb is provided. This modularly filled composite honeycomb includes a plurality of honeycomb cells filled with functional materials. The functional materials in each honeycomb cell may be the same or different, and each functional material includes a foaming material.

[0055] By filling individual honeycomb cells, a more precise design of the microwave absorbing interface can be achieved. Furthermore, the filling process allows for precise control of the quality of each part of the honeycomb, giving it good mechanical strength. In addition, the lightweight foam material is beneficial for the fabrication of lightweight stealth devices. Compared with traditional impregnation and spraying processes for microwave absorbing slurry, it can avoid phenomena such as shrinkage and deformation of the honeycomb pores after curing caused by different amounts of slurry adhering to different parts of the honeycomb, thus significantly improving the structural stability of the honeycomb.

[0056] In some embodiments, each functional material independently includes at least one of a first functional layer, a second functional layer, a third functional layer, a fourth functional layer, a fifth functional layer, a sixth functional layer, a seventh functional layer, and an eighth functional layer; when the functional material includes multiple functional layers, each functional layer is stacked along the T-direction of the modular filled composite honeycomb to form the functional material; the thickness of each functional layer is independently 0.05 to 1 times the height of the honeycomb pores.

[0057] In some embodiments, the material of the first functional layer is a high-resistivity-loss foam material with a sheet resistance of 50~100 kΩ / □, and its composition does not include hollow microwave absorbing microspheres.

[0058] The material of the second functional layer is a medium-resistance loss type foam material with a sheet resistance of 10~50 kΩ / □, and its composition does not include hollow microwave absorbing microspheres.

[0059] The material of the third functional layer is a low-resistance-loss foam material with a sheet resistance of 5~10 kΩ / □, and its composition does not include hollow microwave absorbing microspheres.

[0060] The fourth functional layer is made of an ultra-low resistance loss foam material with a sheet resistance of 1~5 kΩ / □, and its composition does not include hollow microwave absorbing microspheres.

[0061] The fifth functional layer is made of a high magnetic loss foam material with a permeability of 3~5 H / m and an absorption band of L~S.

[0062] The material of the sixth functional layer is a low-resistivity loss type three-dimensional thin-walled hollow microwave absorbing material with a sheet resistance of 5~10kΩ / □, and its composition includes hollow microwave absorbing microspheres.

[0063] The material of the seventh functional layer is a medium-resistivity loss type three-dimensional thin-walled hollow microwave absorbing material with a sheet resistance of 10~50 kΩ / □, and its composition includes hollow microwave absorbing microspheres.

[0064] The material of the eighth functional layer is a high-resistivity loss type three-dimensional thin-walled hollow microwave absorbing material with a sheet resistance of 50~100 kΩ / □, and its composition includes hollow microwave absorbing microspheres.

[0065] By filling the honeycomb holes with functional materials (at least one of foamed materials and thin-walled hollow absorbing materials), a lightweight stealth structure can be produced, contributing to the weight reduction of stealth equipment. Furthermore, compared to honeycomb stealth structures made by impregnation or coating with absorbing slurry, this structure exhibits higher stability and is not prone to deformation or cracking due to varying slurry application amounts, thus maintaining structural stability. In addition, traditional stealth structures are designed on a single piece of absorbing honeycomb blank, resulting in a rough absorbing interface and poor absorption performance. The modular filling and combination honeycomb described in this application allows for precise design of individual honeycomb holes, improving the absorption performance of the honeycomb. Especially at the interface absorbing surface of the high-frequency antenna integrated into the component, this method satisfies antenna stealth requirements without affecting antenna gain. The first to eighth functional layers provided in this application can achieve multi-band, wide-band absorption of electromagnetic waves, effectively improving the electromagnetic stealth performance of stealth equipment. This is applicable to defense, aerospace, and aviation fields, and is of significant value in enhancing the stealth and battlefield survivability of aircraft, ships, and ground vehicles. Furthermore, each functional material includes at least one of a first functional layer, a second functional layer, a third functional layer, a fourth functional layer, and a fifth functional layer. These optimizations help to further improve the structural stability of the modular filled composite honeycomb.

[0066] In this application, the materials (foamed materials) of the first to fifth functional layers are obtained by mixing microwave absorbing material, thermoplastic elastomer, foaming agent and additives to first prepare a foamed preform, and then curing it; the materials (thin-walled hollow microwave absorbing material) of the sixth to eighth functional layers are obtained by mixing microwave absorbing material, thin-walled hollow body and additives to first prepare a thin-walled hollow microwave absorbing preform, filling the foamed preform or thin-walled hollow microwave absorbing preform into the honeycomb cells, and then curing and heating the honeycomb.

[0067] Specifically, the high resistance loss type functional material is obtained by heating a high resistance loss type foamed preform, which comprises the following components in parts by weight: 50-100 parts thermoplastic polyester elastomer (TPEE), 3-10 parts carbon-based microwave absorbing material, 0.1-2 parts carbon-based short fiber, 0.5-10 parts foaming agent, 0.03-3 parts vulcanizing agent, 0.05-0.5 parts antioxidant, 0.5-4 parts coupling agent, and 0.2-4 parts dispersant.

[0068] The medium-resistance loss type functional material is obtained by heating a medium-resistance loss type foam preform. The difference between the composition of the medium-resistance loss type foam preform and the composition of the high-resistance loss type foam preform is only that the carbon-based microwave absorbing material has a weight of 6 to 13 parts and the carbon-based short fiber has a weight of 1 to 3 parts.

[0069] The low-resistance loss functional material is obtained by heating a low-resistance loss foam preform. The difference between the composition of the low-resistance loss foam preform and the high-resistance loss foam preform is that the carbon-based microwave absorbing material has a weight of 9 to 16 parts and the carbon-based short fiber has a weight of 2 to 4 parts.

[0070] The ultra-low resistance loss type functional material is obtained by heating an ultra-low resistance loss type foam preform. The difference between the composition of the ultra-low resistance loss type foam preform and the composition of the high resistance loss type foam preform is only that the carbon-based microwave absorbing material has a weight of 12 to 20 parts and the carbon-based short fiber has a weight of 3 to 5 parts.

[0071] The high magnetic loss type functional material is obtained by heating a high magnetic loss type foam preform. The difference between the composition of the high magnetic loss type foam preform and the composition of the high resistance loss type foam preform is that the high magnetic loss type foam preform does not contain carbon-based microwave absorbing materials and carbon-based short fibers, but includes 20-40 parts of magnetic microwave absorbing materials and 5-15 parts of magnetic short fibers.

[0072] The low-resistance-loss type three-dimensional thin-walled hollow microwave absorbing material is obtained by heating a low-resistance-loss type three-dimensional thin-walled hollow microwave absorbing preform. The low-resistance-loss type three-dimensional thin-walled hollow microwave absorbing preform comprises the following components in parts by weight: 12-18 parts of carbon-based microwave absorbing material and 70-90 parts of alumina hollow spheres; the alumina hollow spheres are alumina hollow spheres A, and the diameter of alumina hollow spheres A is 1-1.5 mm.

[0073] The medium-resistance loss type three-dimensional thin-walled hollow microwave absorbing material is obtained by heating a medium-resistance loss type three-dimensional thin-walled hollow microwave absorbing preform. The difference between the composition of the medium-resistance loss type three-dimensional thin-walled hollow microwave absorbing preform and the composition of the low-resistance loss type three-dimensional thin-walled hollow microwave absorbing preform is only that the carbon-based microwave absorbing material has a weight ratio of 6 to 12 parts; wherein, the alumina hollow spheres are a mixture of alumina hollow sphere A and alumina hollow sphere B, the weight ratio of alumina hollow sphere A to alumina hollow sphere B is (20 to 40): (40 to 50), the diameter of alumina hollow sphere A is 1 to 1.5 mm, and the diameter of alumina hollow sphere B is 2.2 to 3 mm.

[0074] The high-resistivity-loss type three-dimensional thin-walled hollow microwave absorbing material is obtained by heating a high-resistivity-loss type three-dimensional thin-walled hollow microwave absorbing preform. The only difference between the composition of the high-resistivity-loss type three-dimensional thin-walled hollow microwave absorbing preform and the low-resistivity-loss type three-dimensional thin-walled hollow microwave absorbing preform is that the carbon-based microwave absorbing material has a weight ratio of 2 to 6 parts; wherein, the alumina hollow spheres are alumina hollow spheres B, and the diameter of the alumina hollow spheres B is 2.2 to 3 mm.

[0075] Typically, and not limitingly, in this application, carbon-based microwave absorbing materials include at least one of graphene, carbon black, and carbon nanotubes; carbon-based short fibers include at least one of carbon fiber and silicon carbide fiber; magnetic microwave absorbing materials include at least one of ferrite, iron carbonyl, and magnetic metal micropowder; magnetic short fibers include ferrite nanofibers, etc. All of the above materials possess excellent microwave absorption properties. Furthermore, foaming agents, vulcanizing agents, antioxidants, coupling agents, and dispersants can be commonly used materials; for example, the foaming agent can be thermally expanded foamed microspheres, specifically at least one of POLYCHEN's 200DU35 and 220DU3, etc.; the vulcanizing agent can be triallyl isocyanurate (TAIC); the antioxidant can be tricalcium phosphate (TCP); the coupling agent can be dichlorosilane; and the dispersant can be stearic acid. The above components are readily available and possess good processing properties.

[0076] In some embodiments, along any direction perpendicular to the T-direction of the modularly filled composite honeycomb, the following functional materials are sequentially and cyclically filled into each honeycomb cell: first functional material, second functional material, third functional material, fourth functional material, third functional material, and second functional material;

[0077] The first functional material consists of a first functional layer;

[0078] Second functional material: The second functional layer and the first functional layer are stacked sequentially from bottom to top;

[0079] Third functional material: The third functional layer, the second functional layer, and the first functional layer are stacked sequentially from bottom to top;

[0080] Fourth functional material: The third functional layer, the second functional layer, and the first functional layer are stacked sequentially from bottom to top;

[0081] The thickness of the first functional layer is 0.05 to 0.15 times the height of the honeycomb cells, the thickness of the second functional layer is 0.15 to 0.2 times the height of the honeycomb cells, and the thickness of the third functional layer is 0.15 to 0.25 times the height of the honeycomb cells.

[0082] In the above embodiments, the modular filled composite honeycomb has a sawtooth-like mirror deflection and scattering structure along the T-direction, combined with impedance gradient. By designing the structure of the modular filled composite honeycomb in this way, on the one hand, the foaming material inside the honeycomb cells can be arranged in a hierarchical manner, so that the modular filled composite honeycomb has different electromagnetic absorption capabilities, achieving effective absorption and deflection of broadband electromagnetic waves, thereby reducing the radar cross section (RCS) of stealth equipment such as aircraft. On the other hand, it can avoid unnecessary increase in structural weight, reduce the amount of material used, and also enhance the shear resistance of the honeycomb cells, thereby improving its structural stability.

[0083] In some embodiments, along any direction perpendicular to the T-direction of the modular filled composite honeycomb, the following foaming material is sequentially filled into each honeycomb cell:

[0084] Fifth functional material: The fifth functional layer, the fourth functional layer, and the fifth functional layer are stacked sequentially from bottom to top;

[0085] Fifth functional material;

[0086] Sixth functional material: The fifth functional layer, the third functional layer, and the fifth functional layer are stacked sequentially from bottom to top;

[0087] Seventh functional material: The fifth functional layer, the second functional layer, and the fifth functional layer are stacked sequentially from bottom to top;

[0088] Eighth functional material: The fifth functional layer, the first functional layer, and the fifth functional layer are stacked sequentially from bottom to top;

[0089] The thickness of the first functional layer is 0.7 to 0.9 times the height of the honeycomb cells, the thickness of the second functional layer is 0.7 to 0.9 times the height of the honeycomb cells, the thickness of the third functional layer is 0.7 to 0.9 times the height of the honeycomb cells, the thickness of the fourth functional layer is 0.7 to 0.9 times the height of the honeycomb cells, and the thickness of the fifth functional layer is 0.05 to 0.15 times the height of the honeycomb cells.

[0090] By combining an impedance-gradient electromagnetic absorption structure with a low-frequency specular reflective layer with high magnetic loss on the honeycomb T-shaped end face, especially during side radar detection, the incident wave can be effectively absorbed into the cavity and absorbed inside the cavity, reducing echo formation. This is suitable for stealth structural treatment of the wingtips and fuselage side strakes of fighter jets.

[0091] In some embodiments, the following functional materials are filled into each cell along any direction perpendicular to the T-direction of the modular filled composite cell:

[0092] Ninth functional material: The fourth functional layer, the third functional layer, the second functional layer, and the first functional layer are stacked sequentially from bottom to top;

[0093] The thickness of the first functional layer is 0.05 to 0.15 times the height of the honeycomb cells, the thickness of the second functional layer is 0.1 to 0.2 times the height of the honeycomb cells, the thickness of the third functional layer is 0.2 to 0.3 times the height of the honeycomb cells, and the thickness of the fourth functional layer is 0.3 to 0.5 times the height of the honeycomb cells.

[0094] The aforementioned modular filling combined honeycomb T-direction is an impedance-gradient electromagnetic absorption structure, suitable for stealth treatment of leading edge parts such as the wing leading edge and tail leading edge of fighter jets. Its absorption direction of incident waves is approximately consistent with the direction of force, which has good wave absorption performance, high structural stability, and long service life.

[0095] In some embodiments, the following functional materials are filled into each cell along any direction perpendicular to the T-direction of the modular filled composite cell:

[0096] Tenth functional material: The fourth, sixth, seventh and eighth functional layers are stacked sequentially from bottom to top;

[0097] The thickness of the fourth functional layer is 0.2 to 0.3 times the height of the honeycomb cells, the thickness of the sixth functional layer is 0.2 to 0.4 times the height of the honeycomb cells, the thickness of the seventh functional layer is 0.2 to 0.3 times the height of the honeycomb cells, and the thickness of the eighth functional layer is 0.1 to 0.2 times the height of the honeycomb cells.

[0098] In the above embodiments, the ends of each honeycomb hole may or may not be on the same horizontal plane.

[0099] By setting an impedance-gradient electromagnetic absorption structure in the T-direction of a modular filled composite honeycomb and combining it with a three-dimensional hollow structure, the absorption interface can be any curved surface as the structure changes. This modular filled composite honeycomb is suitable for stealth treatment of parts with built-in high-frequency antennas, such as the leading edge of the wing and the leading edge of the tail of stealth fighters. At the same time, it can perform more precise 3D absorbing interface design on the machined 3D honeycomb structure shape, and further enhance the absorbing effect of the absorbing interface.

[0100] In some embodiments, the following functional materials are filled into each cell along any direction perpendicular to the T-direction of the modular filled composite cell:

[0101] Eleventh functional material: The first functional layer, the second functional layer, the third functional layer, the fourth functional layer, the third functional layer, the second functional layer, and the first functional layer are stacked sequentially from bottom to top;

[0102] The thickness of the first functional layer is 0.05 to 0.1 times the height of the honeycomb cells, the thickness of the second functional layer is 0.1 to 0.15 times the height of the honeycomb cells, the thickness of the third functional layer is 0.1 to 0.15 times the height of the honeycomb cells, and the thickness of the fourth functional layer is 0.2 to 0.4 times the height of the honeycomb cells.

[0103] In this embodiment, the modular filled composite honeycomb has an impedance-gradient electromagnetic absorption structure in the T direction, which is suitable for absorbing incident waves from both the top and bottom directions of the modular filled composite honeycomb. Since the aileron of the fighter jet is a structure that can rotate up and down, the modular filled composite honeycomb in this embodiment is suitable for stealth treatment of the aileron of the fighter jet.

[0104] In another typical embodiment of this application, a method for preparing a modularly filled composite honeycomb is provided, comprising the following steps:

[0105] S1. Prepare different types of foamed preforms and thin-walled hollow microwave absorbing preforms to obtain high-resistivity-loss foamed preforms, medium-resistivity-loss foamed preforms, low-resistivity-loss foamed preforms, extremely low-resistivity-loss foamed preforms, high-magnetic-loss foamed preforms, low-resistivity-loss three-dimensional thin-walled hollow microwave absorbing preforms, medium-resistivity-loss three-dimensional thin-walled hollow microwave absorbing preforms, and high-resistivity-loss three-dimensional thin-walled hollow microwave absorbing preforms.

[0106] S2, cut different types of foamed preforms to obtain different cylindrical strips;

[0107] S3, cut different cylindrical strips according to the required thickness to obtain the same or different foamed prefabricated blocks;

[0108] S4. According to the design, foamed prefabricated blocks or foamed prefabricated blocks and thin-walled hollow microwave absorbing prefabricated blocks are stacked from bottom to top in different honeycomb cells of the modular filling combined honeycomb to obtain honeycomb semi-finished products.

[0109] S4, the honeycomb semi-finished product is cured to obtain a modular filled composite honeycomb with one or more functional layers in the honeycomb cells.

[0110] In the above embodiments of this application, by first preparing foamed prefabricated blocks and thin-walled hollow absorbing prefabricated bodies with specific microwave absorption properties, the microwave absorbing material in a single honeycomb cell can be adjusted according to the microwave absorption requirements of the stealth device, and suitable prefabricated bodies can be stacked together. Using this method, structures such as impedance-gradient electromagnetic absorption structures can be formed along the T-direction of the modular filled composite honeycomb or perpendicular to the T-direction of the modular filled composite honeycomb, applicable to multiple parts of the stealth device, facilitating efficient absorption and conversion of incident waves, and significantly improving the stealth effect. Furthermore, by directly stacking prefabricated blocks in the honeycomb matrix, this method avoids the problem of poor honeycomb structure stability easily caused by traditional impregnation and coating methods, helping to extend the service life of the honeycomb. In addition, if the microwave absorption performance cannot meet expectations during subsequent use, other foamed prefabricated bodies can be filled and further cured; secondary processing of the honeycomb can significantly reduce production costs.

[0111] Typical, but not limiting, methods for preparing foamed preforms include the following steps:

[0112] S11, Place the thermoplastic polyester elastomer in an oven to dry;

[0113] S12, add the dried thermoplastic polyester elastomer into a mixer and stir at 140~190 ℃ for 3~6 min. Then add antioxidant, coupling agent and dispersant respectively and stir for 3~6 min to obtain the first mixture.

[0114] S13, then add microwave absorbing material to the internal mixer and stir for 6-12 minutes to obtain the second mixture;

[0115] S14, turn on the open mill, initially set the roller gap to 2~5 mm and the roller temperature to 130~180 ℃, place the second mixture on the open mill for plasticizing and then mill for 3~5 min, add short fiber filaments in small amounts and mill for 3~5 min in multiple batches, adjust the roller gap to 1.5~2 mm, add foaming agent evenly and mill for 3~5 min, then add vulcanizing agent and mill for 5~10 min to obtain foamed preform.

[0116] The foamed preforms prepared by the above method have certain mechanical strength and are suitable for preparing modular filled composite honeycomb by filling method.

[0117] In some embodiments, cylindrical strips are cut into foamed prefabricated blocks using hot pressing, with hot pressing conditions of 150~190 ℃ and 0.3~0.5 MPa. Under these conditions, hot pressing results in high flatness and high processing accuracy.

[0118] In some implementations, the diameter of the cylindrical strip is 50% to 80% of the diameter of the honeycomb pores.

[0119] Limiting the diameter of the cylindrical strip as described above allows the diameter of the heated and cured foam block to match the diameter of the honeycomb pores, resulting in a compact modular filled honeycomb structure, improving the structural stability of the honeycomb, and thus improving its service life.

[0120] A typical, but not limiting, method for preparing thin-walled hollow microwave absorbing preforms is as follows: Hollow alumina spheres are impregnated and mixed in a microwave absorbing slurry (with a carbon-based microwave absorbing material as the substrate) for 1-3 minutes. The mixture is then lifted using a mesh screen, drained for 3-8 minutes, and transferred to a rotary screen box for rotation and hot air surface drying for 5-15 minutes. To achieve the required resistance value, the surface-dried product can be pre-cured at 100-150 °C for 1-2 hours. The above steps are repeated until the resistance value meets the requirements, but the final pre-curing is unnecessary, allowing the thin-walled hollow microwave absorbing preform to undergo final curing and bonding within the honeycomb pores. This method is simple and allows for uniform coverage of the microwave absorbing material on the outer wall of the hollow alumina spheres.

[0121] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0122] The materials used in the examples are as follows:

[0123] The honeycomb substrate is aramid honeycomb with a pore size of 3.2 mm, a density of 64 kg / m³, and a T-axis dimension of 40±1 mm.

[0124] The antioxidant is tricalcium phosphate; the coupling agent is dichlorosilane; the dispersant is stearic acid; the carbon-based microwave absorbing material is graphene; the carbon-based short fiber is carbon fiber; the foaming agent is 200DU35; the vulcanizing agent is triallyl isocyanurate; the magnetic microwave absorbing material is ferrite; the magnetic short fiber is ferrite nanofiber; the diameter of alumina hollow sphere A is 1~1.3 mm, and the wall thickness is 0.03~0.07 mm; the diameter of alumina hollow sphere B is 2.3~2.6 mm, and the wall thickness is 0.05~0.1 mm.

[0125] The preparation method of high-resistivity loss type foamed preform is as follows:

[0126] S11, Place the TPEE in an oven and dry it at 100℃ for 2 hours;

[0127] S12, 100 parts of dried thermoplastic polyester elastomer were added to a mixer and stirred at 160 °C for 5 min, with the stirring rate controlled at 60 r / min. Then, 0.2 parts of antioxidant, 1.8 parts of coupling agent, and 2.2 parts of dispersant were added and stirred for 5 min to obtain the first mixture.

[0128] S13, then add 4.9 parts of carbon-based microwave absorbing material to the internal mixer and stir for 10 min to obtain the second mixture;

[0129] S14. Open the open mill, initially set the roller gap to 3 mm and the roller temperature to 155 ℃. Place the second mixture on the open mill for plasticizing and then mill for 5 min. Add 0.6 parts of carbon-based short fiber filaments in small, even amounts multiple times and mill for 5 min. Adjust the roller gap to 1.5 mm and add 0.5~10 parts of foaming agent evenly and mill for 5 min. Then add 0.5 parts of vulcanizing agent and mill for 5~10 min to obtain the foamed preform.

[0130] The only difference between the preparation method of medium resistance loss type foamed preform and the preparation method of high resistance loss type foamed preform is that the weight parts of carbon-based microwave absorbing material in S13 are 7.8 parts and the weight parts of carbon-based short fiber are 1.5 parts.

[0131] The only difference between the preparation method of low-resistance loss type foamed preform and the preparation method of high-resistance loss type foamed preform is that the carbon-based microwave absorbing material in S13 is 12 parts by weight and the carbon-based short fiber is 2.6 parts by weight.

[0132] The only difference between the preparation method of ultra-low resistance loss type foamed preform and the preparation method of high resistance loss type foamed preform is that the carbon-based microwave absorbing material in S13 is 16 parts by weight and the carbon-based short fiber is 3.5 parts by weight.

[0133] The only difference between the preparation method of high magnetic loss type foamed preform and the preparation method of high resistance loss type foamed preform is that S13 does not contain carbon-based microwave absorbing materials and carbon-based short fibers, but contains 32 parts of magnetic microwave absorbing materials and 11 parts of magnetic short fibers.

[0134] The preparation method of the low-resistance loss type three-dimensional thin-walled hollow microwave absorbing preform is as follows: Alumina hollow spheres are added to the microwave absorbing slurry (the substrate is a carbon-based microwave absorbing material) for impregnation and mixing. The impregnation time is 1.5 min. Then, the mixture is lifted with a mesh screen, drained for 5 min, and transferred to a rotary screen box for rotation and hot air surface drying for 10 min. Then, it is transferred to an oven for pre-curing for 1 hour at a pre-curing temperature of 150℃. The above steps are repeated until the resistance value meets the requirements. However, after the last repeated impregnation process, only surface drying is required; no further pre-curing is needed (this is for final curing and bonding between the spheres inside the honeycomb cells after surface drying). In this low-resistance loss type three-dimensional thin-walled hollow microwave absorbing preform, there are 18 parts of carbon-based microwave absorbing material and 70 parts of alumina hollow sphere A.

[0135] The difference between the preparation method of the medium resistance loss type three-dimensional thin-walled hollow microwave absorbing preform and the low resistance loss type three-dimensional thin-walled hollow microwave absorbing preform is only that: the carbon-based microwave absorbing material is impregnated according to the above steps, 12 parts of alumina hollow sphere A, 40 parts of alumina hollow sphere B, and the alumina hollow sphere A and alumina hollow sphere B are graded and mixed for use.

[0136] The difference between the preparation method of the high-resistivity-loss type three-dimensional thin-walled hollow microwave absorbing preform and the low-resistivity-loss type three-dimensional thin-walled hollow microwave absorbing preform lies only in the following steps: impregnation with 6 parts of carbon-based microwave absorbing material and 70 parts of alumina hollow spheres B.

[0137] Example 1

[0138] One embodiment of the modular filled composite honeycomb of this application is shown in the schematic diagram of the structure of the modular filled composite honeycomb of this embodiment. Figure 1 As shown in the A structure, the preparation method is as follows:

[0139] S1, using a cylindrical strip cutting die, cut 400 mm... High-resistivity-loss foamed preforms, medium-resistivity-loss foamed preforms, and low-resistivity-loss foamed preforms were hot-pressed at 150 °C and 0.5 MPa for 3 s to obtain cylindrical strips with a length of 400 mm and a diameter of 2.1 mm.

[0140] S2, the cylindrical strip is cut into high-resistivity-loss foamed precast blocks, medium-resistivity-loss foamed precast blocks and low-resistivity-loss foamed precast blocks with thicknesses of 0.1 times, 0.2 times and 0.25 times the height of the honeycomb cells, respectively;

[0141] S3, according to the design, along a direction perpendicular to the T-direction of the modular filled composite honeycomb, the following foamed prefabricated blocks are stacked sequentially from bottom to top in each honeycomb cell of the honeycomb matrix:

[0142] First honeycomb cell: High resistivity loss type foamed prefabricated block (after curing, it serves as the first functional layer, with a sheet resistance of 80~95 kΩ / □);

[0143] Second honeycomb cells: medium resistance loss type foamed preform (after curing, it serves as the second functional layer, with a sheet resistance of 30~45 kΩ / □), high resistance loss type foamed preform;

[0144] Third honeycomb cells: low resistance loss type foamed preform (after curing, it serves as the third functional layer, with a sheet resistance of 7~9.5 kΩ / □), medium resistance loss type foamed preform, and high resistance loss type foamed preform.

[0145] Fourth type of honeycomb: low resistance loss type foamed precast block, low resistance loss type foamed precast block, medium resistance loss type foamed precast block, high resistance loss type foamed precast block;

[0146] Fifth type of honeycomb: low resistance loss type foamed precast block, medium resistance loss type foamed precast block, high resistance loss type foamed precast block;

[0147] Sixth honeycomb structure: medium resistance loss type foamed prefabricated block, high resistance loss type foamed prefabricated block;

[0148] Using the first to sixth honeycomb cells as a cycle, the cycle is repeated along the direction perpendicular to the T-direction of the modular filling composite honeycomb to obtain a honeycomb semi-finished product;

[0149] S4. The honeycomb semi-finished product is cured at 200℃, and the heating air is transmitted along the T direction of the honeycomb holes to obtain a modular filling combination honeycomb.

[0150] Example 2

[0151] One embodiment of the modular filled composite honeycomb of this application is shown in the schematic diagram of the structure of the modular filled composite honeycomb of this embodiment. Figure 1 The B structure is shown in the figure, and the preparation method is as follows:

[0152] S1, using a cylindrical strip cutting die, cut 400 mm... High magnetic loss type foamed preform, extremely low resistance loss type foamed preform, low resistance loss type foamed preform, medium resistance loss type foamed preform, and high resistance loss type foamed preform were hot-pressed at 150 ℃ and 0.5 MPa for 3 s to obtain cylindrical strips with a length of 400 mm and a diameter of 2.1 mm.

[0153] S2, cut high magnetic loss type foamed preform cylindrical strips into high magnetic loss type foamed preform blocks with a thickness of 0.08 times the height of the honeycomb cells; cut ultra-low resistance loss type foamed preform cylindrical strips into ultra-low resistance loss type foamed preform blocks with a thickness of 0.8 times the height of the honeycomb cells; cut low resistance loss type foamed preform cylindrical strips into low resistance loss type foamed preform blocks with a thickness of 0.8 times the height of the honeycomb cells; cut medium resistance loss type foamed preform cylindrical strips into medium resistance loss type foamed preform blocks with a thickness of 0.8 times the height of the honeycomb cells; cut high resistance loss type foamed preform cylindrical strips into high resistance loss type foamed preform blocks with a thickness of 0.8 times the height of the honeycomb cells.

[0154] S3, according to the design, along a direction perpendicular to the T-direction of the modular filled composite honeycomb, the following foamed prefabricated blocks are stacked sequentially from bottom to top in each honeycomb cell of the honeycomb matrix:

[0155] First honeycomb cells: High magnetic loss type foamed preform (after curing, it serves as the fifth functional layer, with an absorption band of L~S band and a permeability of 3~5 H / m), extremely low resistance loss type foamed preform (after curing, it serves as the fourth functional layer, with a sheet resistance of 2.5~4.5 kΩ / □), and high magnetic loss type foamed preform.

[0156] Second honeycomb cells: high magnetic loss type foamed preform, extremely low resistance loss type foamed preform, high magnetic loss type foamed preform;

[0157] Third honeycomb cells: high magnetic loss type foamed preform, low resistance loss type foamed preform, and high magnetic loss type foamed preform;

[0158] Fourth type of honeycomb: high magnetic loss type foamed preform, medium resistance loss type foamed preform, and high magnetic loss type foamed preform;

[0159] Fifth honeycomb cells: high magnetic loss type foamed preform, high resistance loss type foamed preform, high magnetic loss type foamed preform;

[0160] S4. The honeycomb semi-finished product is cured at 200 ℃, and the heating air is transmitted along the T direction of the honeycomb holes to obtain a modular filling combination honeycomb.

[0161] Example 3

[0162] One embodiment of the modular filled composite honeycomb of this application is shown in the schematic diagram of the structure of the modular filled composite honeycomb of this embodiment. Figure 2 The C structure is shown in the figure, and the preparation method is as follows:

[0163] S1, using a cylindrical strip cutting die, cut 400 mm... Extremely low resistance loss type foamed preform, low resistance loss type foamed preform, medium resistance loss type foamed preform, and high resistance loss type foamed preform of 400 mm were hot-pressed at 150℃ and 0.5MPa for 3s to obtain a cylindrical strip with a length of 400 mm and a diameter of 2.1 mm.

[0164] S2, cut the ultra-low resistance loss type foamed preform cylindrical strips into ultra-low resistance loss type foamed preform blocks with a thickness of 0.4 times the height of the honeycomb cells; cut the low resistance loss type foamed preform cylindrical strips into low resistance loss type foamed preform blocks with a thickness of 0.25 times the height of the honeycomb cells; cut the medium resistance loss type foamed preform cylindrical strips into medium resistance loss type foamed preform blocks with a thickness of 0.15 times the height of the honeycomb cells; cut the high resistance loss type foamed preform cylindrical strips into high resistance loss type foamed preform blocks with a thickness of 0.1 times the height of the honeycomb cells.

[0165] S3, according to the design, along a direction perpendicular to the T-direction of the modular filled composite honeycomb, the following foamed prefabricated blocks are stacked sequentially from bottom to top in each honeycomb cell of the honeycomb matrix:

[0166] Honeycomb cells: ultra-low resistance loss type foamed precast blocks, low resistance loss type foamed precast blocks, medium resistance loss type foamed precast blocks, and high resistance loss type foamed precast blocks;

[0167] S4. The honeycomb semi-finished product is cured at 200℃, and the heating air is transmitted along the T direction of the honeycomb holes to obtain a modular filling combination honeycomb.

[0168] Example 4

[0169] One embodiment of the modular filled composite honeycomb of this application is shown in the schematic diagram of the structure of the modular filled composite honeycomb of this embodiment. Figure 2 The D structure is shown in the figure, and the preparation method is as follows:

[0170] S1, using a cylindrical strip cutting die, cut 400 mm... A 400 mm ultra-low resistance loss foamed preform was hot-pressed at 150 °C and 0.5 MPa for 3 s to obtain a cylindrical strip with a length of 400 mm and a diameter of 2.1 mm.

[0171] S2, cut the cylindrical strip of the ultra-low resistance loss foamed preform into ultra-low resistance loss foamed preform blocks with a thickness of 0.2 times the height of the honeycomb cells;

[0172] S3, according to the design, along a direction perpendicular to the T-direction of the modular filled composite honeycomb, the following prefabricated blocks are stacked sequentially from bottom to top in each honeycomb cell of the honeycomb matrix:

[0173] Cellular structure: A low-resistivity-loss foamed prefabricated block; a low-resistivity-loss three-dimensional thin-walled hollow absorbing prefabricated layer with a thickness of 0.3 times the cell height, formed by stacking low-resistivity-loss three-dimensional thin-walled hollow absorbing prefabricated material (after curing, it serves as the sixth functional layer, with a sheet resistance of 5~7 kΩ / □); a medium-resistivity-loss three-dimensional thin-walled hollow absorbing prefabricated layer with a thickness of 0.3 times the cell height, formed by stacking medium-resistivity-loss three-dimensional thin-walled hollow absorbing prefabricated material (after curing, it serves as the seventh functional layer, with a sheet resistance of 10~25 kΩ / □); and a high-resistivity-loss three-dimensional thin-walled hollow absorbing prefabricated layer with a thickness of 0.2 times the cell height, formed by stacking high-resistivity-loss three-dimensional thin-walled hollow absorbing prefabricated material (after curing, it serves as the eighth functional layer, with a sheet resistance of 50~73 kΩ / □).

[0174] S4. The honeycomb semi-finished product is cured at 200 ℃, and the heating air is transmitted along the T direction of the honeycomb holes to obtain a modular filling combination honeycomb.

[0175] Example 5

[0176] One embodiment of the modular filled composite honeycomb of this application is shown in the schematic diagram of the structure of the modular filled composite honeycomb of this embodiment. Figure 2 The E structure is shown in the figure, and the preparation method is as follows:

[0177] S1, using a cylindrical strip cutting die, cut 400 mm... High-resistivity-loss type foamed preform, medium-resistivity-loss type foamed preform, low-resistivity-loss type foamed preform, and ultra-low-resistivity-loss type foamed preform of 400 mm were hot-pressed at 150 ℃ and 0.3MPa for 3 s to obtain cylindrical strips with a length of 400 mm and a diameter of 2.1 mm.

[0178] S2, cut the high-resistivity-loss type foamed precast cylindrical strips into high-resistivity-loss type foamed precast blocks with a thickness of 0.1 times the height of the honeycomb cells; cut the medium-resistivity-loss type foamed precast cylindrical strips into medium-resistivity-loss type foamed precast blocks with a thickness of 0.1 times the height of the honeycomb cells; cut the low-resistivity-loss type foamed precast cylindrical strips into low-resistivity-loss type foamed precast blocks with a thickness of 0.15 times the height of the honeycomb cells; and cut the extremely low-resistivity-loss type foamed precast cylindrical strips into extremely low-resistivity-loss type foamed precast blocks with a thickness of 0.3 times the height of the honeycomb cells.

[0179] S3, according to the design, along a direction perpendicular to the T-direction of the modular filled composite honeycomb, the following foamed prefabricated blocks are stacked sequentially from bottom to top in each honeycomb cell of the honeycomb matrix:

[0180] Cellular cells: high resistance loss type foamed precast blocks, medium resistance loss type foamed precast blocks, low resistance loss type foamed precast blocks, ultra-low resistance loss type foamed precast blocks, low resistance loss type foamed precast blocks, medium resistance loss type foamed precast blocks, and high resistance loss type foamed precast blocks.

[0181] S4. The honeycomb semi-finished product is cured at 200℃, and the heating air is transmitted along the T direction of the honeycomb holes to obtain a modular filling combination honeycomb.

[0182] Example 6

[0183] One embodiment of the modular filled composite honeycomb of this application is shown in the schematic diagram of the structure of the modular filled composite honeycomb of this embodiment. Figure 3 As shown, the only difference between it and Example 4 is that the honeycomb substrate is a curved structure.

[0184] Performance testing

[0185] Performance tests were conducted on Examples 1-5. The test methods are as follows, and the test results are shown in Table 1.

[0186] 1) Absorption performance:

[0187] The test method adopted was GJB2038 Radar Absorbing Material Reflectivity Test Method. The average vertical reflectivity of the honeycomb core material in the T-direction was measured, and the sample size was 300±2 mm (L). 300±2 mm (W) A microwave absorbing cell with a diameter of 40±1 mm (T).

[0188] Performance Description: The performance of a flat plate reflector cannot directly represent the effectiveness of stealth components in the corresponding embodiments of the aircraft. This is because the flat plate reflector test is based on the electromagnetic wave absorption and reflection performance in the direction of the honeycomb thickness, while the stealth components of the aircraft are evaluated by comprehensively considering the characteristics of each part (corresponding embodiments) and the RCS wave absorption stealth characteristics of the front of the aircraft facing the main direction of radar electromagnetic wave detection. Each has its own advantages and disadvantages.

[0189] 2) Mechanical properties:

[0190] The room temperature compressive strength and modulus of stabilized honeycomb core materials were tested using ASTM C365 / 365M. The standard specimen size was 50 ± 1.3 mm (L). 50±1.3 mm (W) 12.7±0.15 mm (T).

[0191] Table 1

[0192]

[0193] As can be seen from the above test results, the modular filling combined honeycomb in this application embodiment not only has good wave absorption performance, but also excellent mechanical properties and high structural stability, making it suitable for application in multiple fields such as aircraft, ships, and ground vehicles.

[0194] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A modular filling composite honeycomb, characterized in that, The modular filled composite honeycomb includes a plurality of honeycomb cells filled with functional materials, wherein the functional materials in each honeycomb cell may be the same or different; each functional material includes a foaming material; each functional material independently includes at least one of a first functional layer, a second functional layer, a third functional layer, a fourth functional layer, a fifth functional layer, a sixth functional layer, a seventh functional layer, and an eighth functional layer; wherein... The first functional layer is made of a high-resistivity-loss foam material with a sheet resistance of 50~100 kΩ / □, and its composition does not include hollow microwave absorbing microspheres; and / or, The second functional layer is made of a medium-resistance loss-type foam material with a sheet resistance of 10~50 kΩ / □, and its composition does not include hollow absorbing microspheres; and / or, The material of the third functional layer is a low-resistivity foam material with a sheet resistance of 5~10 kΩ / □, and its composition does not include hollow microwave absorbing microspheres; and / or, The fourth functional layer is made of an extremely low resistivity foam material with a sheet resistance of 1~5 kΩ / □, and its composition does not include hollow microwave absorbing microspheres; and / or, The fifth functional layer is made of a high-magnetic-loss foam material with a magnetic permeability of 3~5 H / m; and / or, The material of the sixth functional layer is a low-resistivity loss type three-dimensional thin-walled hollow microwave absorbing material with a sheet resistance of 5~10 kΩ / □, and its composition includes hollow microwave absorbing microspheres; and / or, The seventh functional layer is made of a medium-resistivity loss type three-dimensional thin-walled hollow microwave absorbing material with a sheet resistance of 10~50 kΩ / □, and its composition includes hollow microwave absorbing microspheres; and / or, The material of the eighth functional layer is a high-resistivity loss type three-dimensional thin-walled hollow microwave absorbing material with a sheet resistance of 50~100 kΩ / □, and its composition includes hollow microwave absorbing microspheres.

2. The modular filling composite honeycomb according to claim 1, characterized in that, When the functional material comprises multiple functional layers, each functional layer is stacked along the T-direction of the modular filled composite honeycomb to form the functional material; the thickness of each functional layer is independently 0.05 to 1 times the height of the honeycomb pores.

3. The modular filling combined honeycomb according to claim 2, characterized in that, Along any direction perpendicular to the T-direction of the modular filled composite honeycomb, the following functional materials are sequentially and cyclically filled into each of the honeycomb cells: first functional material, second functional material, third functional material, fourth functional material, third functional material, and second functional material; The first functional material is composed of a first functional layer; The second functional material consists of a second functional layer and a first functional layer stacked sequentially from bottom to top. The third functional material consists of a third functional layer, a second functional layer, and a first functional layer stacked sequentially from bottom to top. The fourth functional material consists of a third functional layer, a second functional layer, and a first functional layer stacked sequentially from bottom to top. The thickness of the first functional layer is 0.05 to 0.15 times the height of the honeycomb cells, the thickness of the second functional layer is 0.15 to 0.2 times the height of the honeycomb cells, and the thickness of the third functional layer is 0.15 to 0.25 times the height of the honeycomb cells.

4. The modular filling composite honeycomb according to claim 2, characterized in that, Along any direction perpendicular to the T-direction of the modular filled composite honeycomb, the following functional materials are sequentially filled into each of the honeycomb cells: Fifth functional material: The fifth functional layer, the fourth functional layer, and the fifth functional layer are stacked sequentially from bottom to top; Fifth functional material; Sixth functional material: The fifth functional layer, the third functional layer, and the fifth functional layer are stacked sequentially from bottom to top; Seventh functional material: The fifth functional layer, the second functional layer, and the fifth functional layer are stacked sequentially from bottom to top; Eighth functional material: The fifth functional layer, the first functional layer, and the fifth functional layer are stacked sequentially from bottom to top; The thickness of the first functional layer is 0.7 to 0.9 times the height of the honeycomb holes, the thickness of the second functional layer is 0.7 to 0.9 times the height of the honeycomb holes, the thickness of the third functional layer is 0.7 to 0.9 times the height of the honeycomb holes, the thickness of the fourth functional layer is 0.7 to 0.9 times the height of the honeycomb holes, and the thickness of the fifth functional layer is 0.05 to 0.15 times the height of the honeycomb holes.

5. The modular filling composite honeycomb according to claim 2, characterized in that, Along any direction perpendicular to the T-direction of the modular filled composite honeycomb, the following functional materials are filled into each of the honeycomb cells: Ninth functional material: The fourth functional layer, the third functional layer, the second functional layer, and the first functional layer are stacked sequentially from bottom to top; The thickness of the first functional layer is 0.05 to 0.15 times the height of the honeycomb cells, the thickness of the second functional layer is 0.1 to 0.2 times the height of the honeycomb cells, the thickness of the third functional layer is 0.2 to 0.3 times the height of the honeycomb cells, and the thickness of the fourth functional layer is 0.3 to 0.5 times the height of the honeycomb cells.

6. The modular filling combined honeycomb according to claim 2, characterized in that, Along any direction perpendicular to the T-direction of the modular filled composite honeycomb, the following functional materials are filled into each of the honeycomb cells: Tenth functional material: The fourth, sixth, seventh and eighth functional layers are stacked sequentially from bottom to top; The thickness of the fourth functional layer is 0.2 to 0.3 times the height of the honeycomb holes, the thickness of the sixth functional layer is 0.2 to 0.4 times the height of the honeycomb holes, the thickness of the seventh functional layer is 0.2 to 0.3 times the height of the honeycomb holes, and the thickness of the eighth functional layer is 0.1 to 0.2 times the height of the honeycomb holes.

7. The modular filling composite honeycomb according to claim 6, characterized in that, The sixth functional layer, the seventh functional layer, and the eighth functional layer each independently include at least one of graded A spheres with a diameter of 1~1.5 mm and graded B spheres with a diameter of 2.2~3 mm.

8. The modular filling combined honeycomb according to claim 2, characterized in that, Along any direction perpendicular to the T-direction of the modular filled composite honeycomb, the following functional materials are filled into each of the honeycomb cells: Eleventh functional material: The first functional layer, the second functional layer, the third functional layer, the fourth functional layer, the third functional layer, the second functional layer, and the first functional layer are stacked sequentially from bottom to top; The thickness of the first functional layer is 0.05 to 0.1 times the height of the honeycomb cells, the thickness of the second functional layer is 0.1 to 0.15 times the height of the honeycomb cells, the thickness of the third functional layer is 0.1 to 0.15 times the height of the honeycomb cells, and the thickness of the fourth functional layer is 0.2 to 0.4 times the height of the honeycomb cells.

9. A method for preparing a modular filled composite honeycomb according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Prepare different types of foamed preforms and thin-walled hollow microwave absorbing preforms to obtain high-resistivity-loss foamed preforms, medium-resistivity-loss foamed preforms, low-resistivity-loss foamed preforms, extremely low-resistivity-loss foamed preforms, high-magnetic-loss foamed preforms, low-resistivity-loss three-dimensional thin-walled hollow microwave absorbing preforms, medium-resistivity-loss three-dimensional thin-walled hollow microwave absorbing preforms, and high-resistivity-loss three-dimensional thin-walled hollow microwave absorbing preforms. S2, cut the different types of foamed preforms into different cylindrical strips; S3, cut the different cylindrical strips according to the required thickness to obtain the same or different foamed prefabricated blocks; S4. According to the design, foamed prefabricated blocks or foamed prefabricated blocks and thin-walled hollow microwave absorbing prefabricated blocks are stacked from bottom to top in different honeycomb cells of the modular filled combined honeycomb to obtain a honeycomb semi-finished product. S4, the honeycomb semi-finished product is cured to obtain the modular filling combination honeycomb.

10. The method for preparing a modular filled composite honeycomb according to claim 9, characterized in that, The diameter of the cylindrical strip is 50% to 80% of the diameter of the honeycomb cells.

11. An application of a modularly filled composite honeycomb structure in stealth devices, characterized in that, The modular filling composite honeycomb is the modular filling composite honeycomb according to any one of claims 1 to 8 or the modular filling composite honeycomb prepared by the preparation method according to any one of claims 9 to 10.

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