Composite sandwich structure with electromagnetic damage tolerance and preparation method thereof

Abstract

The present invention discloses a composite sandwich structure with electromagnetic damage tolerance and a preparation method thereof. The preparation method comprises preparing a 3D printing filament containing a dielectric absorber, a 3D printing filament containing a first magnetic absorber, and a 3D printing filament containing a second magnetic absorber; designing a conductive-dissipative skeleton unit; establishing a 3D printing unit model, wherein the model comprises the conductive-dissipative skeleton unit and a first magnetic loss layer, a second magnetic loss layer, and a third magnetic loss layer distributed from top to bottom outside the skeleton unit; obtaining a sandwich structure core layer by 3D printing; and bonding and curing the upper panel, the sandwich structure core layer, and the lower panel to obtain a composite sandwich structure. The composite sandwich structure of the present invention has, for the first time, achieved excellent electromagnetic wave absorption performance within a wide frequency band of 2-18 GHz when the structural damage ratio is less than 40%, which is crucial for improving the maintainability of low-observable aircraft and their survivability in complex electromagnetic environments.

Description

Technical Field

[0001] The present invention belongs to the field of aviation equipment design and manufacturing, and particularly relates to a composite material sandwich structure with electromagnetic damage tolerance and a preparation method thereof. Background Art

[0002] Absorbing composite sandwich structures are widely used in the skins of low-observable aircraft, combining excellent load-bearing and stealth characteristics to ensure the survivability of aircraft in complex electromagnetic environments. Under actual service conditions, low-speed or high-speed impact damage caused by bird strikes, lightning strikes, stratospheric ice particle impacts, and the impact of objects such as stones during aircraft landing leads to three typical damage modes in absorbing composite sandwich structures: panel damage, core damage, and penetrating damage. Near the damaged area, radar waves will produce complex reflection and scattering behaviors, which are easily identified by radar and reduce the survivability of detectable aircraft in complex electromagnetic environments. Therefore, it is crucial to propose a scalable preparation method for composite sandwich structures with both excellent electromagnetic wave absorption performance and electromagnetic damage tolerance to improve the maintainability of aircraft and their survivability in complex electromagnetic environments.

[0003] To address the aforementioned practical engineering challenges of collaboratively designing absorbing performance and electromagnetic damage tolerance, Xing Suli's research group at the National University of Defense Technology (NUDT) has published a paper proposing a gradient absorb-transmit-absorb stacking strategy for absorbing composite laminates. This strategy effectively absorbs electromagnetic wave energy when the perforation damage ratio is less than 20% in the 6-18 GHz frequency band (Compos Commun 2024;46:101838). The group also proposed a multi-resonance peak distributed construction strategy for absorbing honeycomb sandwich structures, effectively absorbing electromagnetic wave energy when the perforation damage ratio is less than 18% in the 4-18 GHz frequency band (Compos Struct 2023;325:117581). The current problems are: 1) The current design concepts or design schemes are based on engineering experience, a large number of simulations or speculations, which limit the design space of electromagnetic damage tolerance and lack a scalable structural design concept to guide industrial production; 2) At the research object level, only two widely used mature structures, laminated structures and honeycomb structures, are considered. The regulatory effect of structural unit design on electromagnetic response cannot be fully exerted, and it is difficult to achieve the best match between absorption performance and damage tolerance; 3) At the level of achieving performance indicators, excellent broadband (2-18GHz) electromagnetic damage tolerance (damage ratio <40% and electromagnetic wave absorption performance can be effectively maintained) has not been achieved. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a broadband, structural damage-resistant composite sandwich structure with electromagnetic damage tolerance and a preparation method thereof.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions.

[0006] A method for preparing a composite sandwich structure with electromagnetic damage tolerance comprises the following steps:

[0007] S1. Preparing 3D printing filaments: mixing a dielectric absorbent filler with a first resin, granulating, and drawing to obtain a 3D printing filament containing a dielectric absorbent, wherein the electromagnetic resonance of the 3D printing filament containing the dielectric absorbent covers a frequency band of 4 GHz to 8 GHz; mixing a first magnetic absorbent filler with a second resin, granulating, and drawing to obtain a 3D printing filament containing a first magnetic absorbent, wherein the electromagnetic resonance of the 3D printing filament containing the first magnetic absorbent covers a frequency band of 8 GHz to 18 GHz; mixing a second magnetic absorbent filler with a third resin, granulating, and drawing to obtain a 3D printing filament containing a second magnetic absorbent, wherein the electromagnetic resonance of the 3D printing filament containing the second magnetic absorbent covers a frequency band of 2 GHz to 4 GHz;

[0008] S2. Design of conductive-dissipative skeleton unit: Design of conductive-dissipative skeleton unit by the following formula (I):

[0009] (I)

[0010] in, l The value of is 8mm~15mm, and the value of c is 0.35~0.7; l Represents the projection size of the skeleton unit in the x, y, and z directions, and is also the thickness of the core layer. c The duty cycle of the skeleton unit is determined and controlled between 20% and 40%.

[0011] S3. Prepare the core layer of the sandwich structure: prepare a multi-bin 3D printing device, add the 3D printing filament containing the dielectric absorbent, the 3D printing filament containing the first magnetic absorbent, the 3D printing filament containing the second magnetic absorbent, and the 3D printing filament containing the first magnetic absorbent into different silos respectively, and establish a 3D printing unit model. The 3D printing unit model is composed of the conductive-dissipative skeleton unit and the first magnetic loss layer, the second magnetic loss layer, and the third magnetic loss layer distributed from top to bottom outside the conductive-dissipative skeleton unit. Use three-dimensional modeling The software arrays the 3D printing unit models to form a sandwich structure core layer model for 3D printing, wherein the conductive-dissipative skeleton unit corresponds to the silo of the 3D printing filament containing the dielectric absorbent, the first magnetic loss layer corresponds to one of the silos of the 3D printing filament containing the first magnetic absorbent, the second magnetic loss layer corresponds to the silo of the 3D printing filament containing the second magnetic absorbent, and the third magnetic loss layer corresponds to another silo of the 3D printing filament containing the first magnetic absorbent. After 3D printing is completed, a sandwich structure core layer is obtained;

[0012] S4. Prepare a composite sandwich structure: use a resin-based composite material plate containing glass fiber as the upper panel, and a resin-based composite material plate containing a second magnetic absorber as the lower panel, the electromagnetic resonance of the resin-based composite material plate containing the second magnetic absorber covers the frequency band of 2GHz to 4GHz, and glue and cure the upper panel, the sandwich structure core layer, and the lower panel to obtain a composite sandwich structure with electromagnetic damage tolerance.

[0013] In the above-mentioned method for preparing a composite sandwich structure with electromagnetic damage tolerance, preferably, in step S1, the mass of the dielectric absorbent filler is 7% to 20% of the total mass of the dielectric absorbent filler and the first resin, the mass of the first magnetic absorbent filler is 30% to 45% of the total mass of the first magnetic absorbent filler and the second resin, and the mass of the second magnetic absorbent filler is 50% to 60% of the total mass of the second magnetic absorbent filler and the third resin.

[0014] In the above-mentioned method for preparing a composite sandwich structure with electromagnetic damage tolerance, preferably, in step S3, the thickness of the first magnetic loss layer is 3mm to 5mm, the thickness of the second magnetic loss layer is 2mm to 4mm, and the thickness of the third magnetic loss layer is 2mm to 3mm.

[0015] The above-mentioned method for preparing a composite sandwich structure with electromagnetic damage tolerance, preferably, in step S1, the dielectric absorbent filler includes one or more of chopped carbon fibers, carbon nanotubes, graphene and carbon black, the average length of the chopped carbon fibers is 0.5 mm to 1.5 mm, the outer diameter of the carbon nanotubes is 40 nm to 60 nm, the particle size of the graphene is 40 nm to 60 nm, and the particle size of the carbon black is 40 nm to 60 nm; the first resin includes one or more of polyamide resin, polylactic acid resin and polyethylene terephthalate; the first magnetic The absorbent filler includes one or more of carbonyl iron, ferrite, iron-cobalt alloy and iron-nickel alloy, the particle size of the first magnetic absorbent filler is 10μm to 50μm, and the second resin includes one or more of polyamide resin, polylactic acid resin and polyethylene terephthalate; the second magnetic absorbent filler includes one or more of carbonyl iron, ferrite, iron-cobalt alloy and iron-nickel alloy, the particle size of the second magnetic absorbent filler is 10μm to 50μm, and the third resin includes one or more of polyamide resin, polylactic acid resin and polyethylene terephthalate.

[0016] In the above-mentioned method for preparing a composite sandwich structure with electromagnetic damage tolerance, preferably, in step S4, in the resin-based composite material plate containing glass fiber, the volume fraction of the glass fiber is 35% to 45%, and the resin includes one or more of epoxy resin, polyamide resin, polylactic acid resin and polyethylene terephthalate; in the resin-based composite material plate containing a second magnetic absorber, the mass fraction of the second magnetic absorber is 50% to 60%, and the resin includes one or more of polyamide resin, polylactic acid resin and polyethylene terephthalate.

[0017] In the above-mentioned method for preparing a composite sandwich structure with electromagnetic damage tolerance, preferably, in step S4, the thickness of the upper panel is 1 mm to 1.5 mm, and the thickness of the lower panel is 1 mm to 2 mm.

[0018] In the above-mentioned method for preparing a composite sandwich structure with electromagnetic damage tolerance, preferably, in step S4, the bonding is implemented using epoxy resin E51 film, the curing temperature is 80°C to 120°C, the pressure during the curing process is controlled at 0.1MPa to 0.15MPa, and the curing time is 1h to 2h.

[0019] As a general technical concept, the present invention also provides a composite material sandwich structure with electromagnetic damage tolerance obtained by the above-mentioned method for preparing the composite material sandwich structure with electromagnetic damage tolerance.

[0020] In the present invention, the conductive-dissipative skeleton unit refers to a type of skeleton structure with a continuous conductive air cavity in the structural unit. The skeleton unit is composed of a waveguide air cavity penetrating in six directions and a skeleton dielectric dissipative layer (dielectric dissipative layer + magnetic dissipative layer). The conductive air cavity plays the role of manipulating the propagation path of electromagnetic waves, and the absorber in the skeleton unit loses electromagnetic wave energy.

[0021] Compared with the prior art, the advantages of the present invention are:

[0022] Compared to traditional structural electromagnetic damage tolerance design concepts, this paper focuses on the novel and unique control properties of periodic structural units (i.e., 3D-printed unit models) on electromagnetic response behavior and their effect on improving electromagnetic damage tolerance. Furthermore, a "conductive-dissipative" structural unit design scheme is proposed to effectively "manipulate" the transmission behavior of electromagnetic waves. For the first time, excellent electromagnetic wave absorption performance is achieved within the 2-18 GHz wide frequency band when the structural damage ratio is less than 40%. This research is crucial for improving the maintainability of low-observable aircraft and their survivability in complex electromagnetic environments.

[0023] The present invention selects three absorbing materials that can generate electromagnetic resonance in different frequency bands, and arranges them in a refined spatial manner to achieve broadband effective absorption in the 2-18 GHz frequency band with a reflectivity of less than -10dB.

[0024] The present invention constructs a magnetic loss layer with different filler contents on the periphery of the dielectric lossy skeleton to form a rich magnetic / dielectric heterogeneous interface, and further uses the conductive dissipative skeleton unit to manipulate the transmission of electromagnetic waves along the magnetic / dielectric heterogeneous interface, so that the electromagnetic wave absorption performance under different damage modes can still be effectively maintained when the damage ratio reaches 40%.

[0025] The composite sandwich structure with electromagnetic damage tolerance of the present invention uses 3D printed conductive-dissipative structural units to achieve fine-grained control of the electromagnetic wave transmission path, thereby effectively manipulating the transmission behavior of the electromagnetic wave. The complex curved surface structure is more conducive to increasing the transmission path of the electromagnetic wave and producing a stronger loss effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the structure of a composite sandwich structure with electromagnetic damage tolerance in Example 1 of the present invention.

[0027] Figure 2 3D view and cross-sectional view of the array unit including the upper panel and the lower panel in Example 1 of the present invention.

[0028] Figure 3 1. (a) The reflectivity diagram of the composite sandwich structure with electromagnetic damage tolerance in Example 1 of the present invention when it is undamaged, and (b) the reflectivity diagram of different damage types when the structural damage accounts for 40%.

[0029] Figure 4 (a) The design concept of the conductive-dissipative structure of the array unit in Example 1 of the present invention and (b) the manipulation effect of the conductive-dissipative structure on electromagnetic waves.

[0030] Legend:

[0031] 1. Sandwich structure core layer; 2. Upper panel; 3. Lower panel; 4. Conductive-dissipative skeleton unit; 5. First magnetic loss layer; 6. Second magnetic loss layer; 7. Third magnetic loss layer; 8. Air cavity. DETAILED DESCRIPTION

[0032] The present invention is further described below with reference to the accompanying drawings and specific preferred embodiments, but the scope of protection of the present invention is not limited thereby. The materials and instruments used in the following examples are all commercially available. The multi-bin 3D printing device used is the iBridger i341, and the 3D modeling software used is either Catia or Abaqus, but is not limited thereto.

[0033] Example 1

[0034] A method for preparing a composite sandwich structure with electromagnetic damage tolerance according to the present invention comprises the following steps:

[0035] S1. Prepare 3D printing filaments: mix a dielectric absorbent filler with a first resin, granulate, and draw to obtain a 3D printing filament containing a dielectric absorbent, so that the electromagnetic resonance of the 3D printing filament containing the dielectric absorbent covers the 4GHz to 8GHz frequency band; mix a first magnetic absorbent filler with a second resin, granulate, and draw to obtain a 3D printing filament containing a first magnetic absorbent, so that the electromagnetic resonance of the 3D printing filament containing the first magnetic absorbent covers the 8GHz to 18GHz frequency band; mix a second magnetic absorbent filler with a third resin, granulate, and draw to obtain a 3D printing filament containing a second magnetic absorbent, so that the electromagnetic resonance of the 3D printing filament containing the second magnetic absorbent covers the 2GHz to 4GHz frequency band The z-band is used; the dielectric absorbent filler is chopped carbon fiber with an average length of 1.2 mm. The first resin is polyamide resin (nylon), and the mass of the dielectric absorbent filler is 10% of the total mass of the dielectric absorbent filler and the first resin. The first magnetic absorbent filler is carbonyl iron with a particle size of 40 μm. The second resin is polyamide resin, and the mass of the first magnetic absorbent filler accounts for 40% of the total mass of the first magnetic absorbent filler and the second resin. The second magnetic absorbent filler is carbonyl iron with a particle size of 40 μm. The third resin is polyamide resin, and the mass of the second magnetic absorbent filler accounts for 60% of the total mass of the second magnetic absorbent filler and the third resin. In this embodiment, the diameter of all three 3D printing filaments is 1.75 mm, but this is not limited to this.

[0036] S2. Design of conductive-dissipative skeleton unit 4: Design of conductive-dissipative skeleton unit 4 by the following formula (I):

[0037] (I)

[0038] in, l The value of is 10 mm, the value of c is 0.52, and the volume of the skeleton accounts for 30%.

[0039] S3. Preparation of sandwich structure core layer 1: prepare a multi-bin 3D printing device. In this embodiment, there are specifically 4 silos. Add 3D printing filaments containing dielectric absorbent, 3D printing filaments containing first magnetic absorbent, 3D printing filaments containing second magnetic absorbent, and 3D printing filaments containing first magnetic absorbent into the 4 silos respectively, and establish a 3D printing unit model (i.e., array unit). The 3D printing unit model is composed of the conductive-dissipative skeleton unit 4 designed above and the first magnetic loss layer 5, the second magnetic loss layer 6, and the third magnetic loss layer 7 distributed from top to bottom on the periphery of the conductive-dissipative skeleton unit 4, as shown in FIG. Figure 2 As shown in the diagram ( Figure 2In the schematic diagram, there is an upper panel 2 and a lower panel 3), a conductive-dissipative skeleton unit 4 is provided with a connected air cavity 8, the thickness of the first magnetic loss layer 5 is 3.7 mm, the thickness of the second magnetic loss layer 6 is 2.7 mm, and the thickness of the third magnetic loss layer 7 is 2.4 mm. In this embodiment, the three sides of the 3D printed unit model are surrounded by a cubic structure (the length and width are both 10 mm). The 3D printed unit model is arrayed using a three-dimensional modeling software. In this embodiment, the 3D printed unit models are arranged to form an array to obtain a sandwich structure core layer model. The length × width × thickness of the sandwich structure core layer model is 3 00mm×300mm×10mm, and then 3D printing is performed, the printer nozzle diameter is 0.3mm, the printer nozzle movement speed is 90mm / s, the conductive-dissipative skeleton unit 4 corresponds to the silo of the 3D printing filament containing the dielectric absorbent, the first magnetic loss layer 5 corresponds to one of the silos of the 3D printing filament containing the first magnetic absorbent, the second magnetic loss layer 6 corresponds to the silo of the 3D printing filament containing the second magnetic absorbent, and the third magnetic loss layer 7 corresponds to another silo of the 3D printing filament containing the first magnetic absorbent. After 3D printing is completed, the sandwich structure core layer 1 is obtained.

[0040] S4. Prepare a composite sandwich structure: use a resin-based composite material plate containing glass fiber as the upper panel 2, and a resin-based composite material plate containing a second magnetic absorbent as the lower panel. The electromagnetic resonance of the resin-based composite material plate containing the second magnetic absorbent covers the 2GHz to 4GHz frequency band. The upper panel 2, the sandwich structure core layer 1, and the lower panel 3 are sequentially bonded using epoxy resin E51 film. The adhesive is cured at 90°C for 1.5h. The pressure is controlled at 0.1MPa during the curing process to obtain a composite sandwich structure with electromagnetic damage tolerance. The structure is shown in the figure. Figure 1 As shown. The volume fraction of glass fiber in the upper panel 2 is 40%, the resin in the upper panel 2 is epoxy resin, and the thickness of the upper panel 2 is 1 mm. The upper panel 2 (resin-based composite material panel containing glass fiber) can be prepared using a vacuum bag-autoclave curing process. The mass fraction of the second magnetic absorbent in the lower panel 3 is 60%, the resin in the lower panel 3 is polyamide resin, and the thickness of the lower panel 3 is 1.6 mm.

[0041] In this embodiment, the dielectric absorbent filler can also be selected from one or more of carbon nanotubes, graphene and carbon black, the outer diameter of the carbon nanotubes is 40nm~60nm, the particle size of the graphene is 40nm~60nm, and the particle size of the carbon black is 40nm~60nm. The first magnetic absorbent filler can also be selected from one or more of ferrite, iron-cobalt alloy and iron-nickel alloy. The second magnetic absorbent filler can also be selected from one or more of ferrite, iron-cobalt alloy and iron-nickel alloy. The first resin, the second resin and the third resin can also be selected from polylactic acid resin, polyethylene terephthalate, etc.

[0042] Wave absorbing performance and electromagnetic damage tolerance verification:

[0043] The composite sandwich structure with electromagnetic damage tolerance prepared in this example was subjected to electromagnetic reflectivity testing in the 2-18 GHz frequency band according to GJB-2038A to verify its electromagnetic wave absorption performance. Subsequently, square damage cells measuring 30 mm x 30 mm were delineated based on the actual structural damage size (e.g., from a lightning strike). Waterjet cutting was used to create different structural damage patterns (panel damage, core damage, and perforation damage) within the damaged cells, along with their damage percentages, for reflectivity testing. The absorption performance of the undamaged composite sandwich structure was compared with that of the damaged composite sandwich structure to verify its electromagnetic damage tolerance.

[0044] Depend on Figure 3 It can be seen that when the damage ratio is less than 40%, the electromagnetic wave absorption performance can be effectively maintained, which proves the effectiveness of the electromagnetic damage tolerance design concept of the present invention. Figure 3 The measured reflectivity-frequency variation curve of the undamaged sandwich structure in (a) is basically consistent with the variation trend of the simulation curve. Figure 3 In (b), when the damage ratio is 40%, the electromagnetic wave absorption performance under different damage modes can be effectively maintained, among which the reflectivity-frequency curve is <-10dB in the 3-18 GHz frequency band. When the damage ratio is <40% in the 2-18 GHz frequency band, the electromagnetic wave absorption performance can be effectively maintained, indicating that the composite sandwich structure with electromagnetic damage tolerance of the present invention has excellent electromagnetic damage tolerance.

[0045] Figure 4 The design concept of designing the array unit into a conductive-dissipative structure in this embodiment is demonstrated. Figure 4 As shown in (a) (with the lower panel), the air cavity 8 (i.e., the waveguide air cavity) connected in the conductive-dissipative skeleton unit 4 forms a waveguide channel, which makes the incident electromagnetic wave reflect and scatter along the direction of multiple open cavities, which is also known as Figure 4 The current density in (b) confirms that the current flows along the surface of the cavity structure, forming a loop cavity, thereby achieving precise control of the electromagnetic response. At the same time, the dielectric and magnetic dissipative layers fully absorb the reflected and scattered electromagnetic wave energy, achieving an optimal synergy between excellent electromagnetic wave absorption performance and electromagnetic damage tolerance.

[0046] The above description is only a preferred embodiment of the present invention and does not constitute any formal limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the spirit and technical solution of the present invention, use the methods and technical contents disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention, still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a composite sandwich structure with electromagnetic damage tolerance, characterized in that: The following steps are involved: S1. Preparing 3D printing filaments: mixing a dielectric absorbent filler with a first resin, granulating, and drawing to obtain a 3D printing filament containing a dielectric absorbent, wherein the electromagnetic resonance of the 3D printing filament containing the dielectric absorbent covers a frequency band of 4 GHz to 8 GHz; mixing a first magnetic absorbent filler with a second resin, granulating, and drawing to obtain a 3D printing filament containing a first magnetic absorbent, wherein the electromagnetic resonance of the 3D printing filament containing the first magnetic absorbent covers a frequency band of 8 GHz to 18 GHz; mixing a second magnetic absorbent filler with a third resin, granulating, and drawing to obtain a 3D printing filament containing a second magnetic absorbent, wherein the electromagnetic resonance of the 3D printing filament containing the second magnetic absorbent covers a frequency band of 2 GHz to 4 GHz; S2. Design of conductive-dissipative skeleton unit (4): Design of conductive-dissipative skeleton unit (4) by the following formula (I): （Ⅰ） in, l The value of is 8mm~15mm, and the value of c is 0.35~0.7; S3. Preparation of sandwich structure core layer (1): prepare a multi-bin 3D printing device, add the 3D printing filament containing dielectric absorbent, the 3D printing filament containing first magnetic absorbent, the 3D printing filament containing second magnetic absorbent, and the 3D printing filament containing first magnetic absorbent into different silos respectively, establish a 3D printing unit model, the 3D printing unit model is composed of the conductive-dissipative skeleton unit (4) and the first magnetic loss layer (5), the second magnetic loss layer (6), and the third magnetic loss layer (7) distributed from top to bottom outside the conductive-dissipative skeleton unit (4), and use a three-dimensional The modeling software arrays the 3D printing unit models to form a sandwich structure core layer model for 3D printing, wherein the conductive-dissipative skeleton unit (4) corresponds to the silo of the 3D printing filament containing the dielectric absorbent, the first magnetic loss layer (5) corresponds to one of the silos of the 3D printing filament containing the first magnetic absorbent, the second magnetic loss layer (6) corresponds to the silo of the 3D printing filament containing the second magnetic absorbent, and the third magnetic loss layer (7) corresponds to another silo of the 3D printing filament containing the first magnetic absorbent. After the 3D printing is completed, the sandwich structure core layer (1) is obtained; S4. Prepare a composite sandwich structure: use a glass fiber-containing resin-based composite material plate as an upper panel (2), and a second magnetic absorbent-containing resin-based composite material plate as a lower panel (3), wherein the electromagnetic resonance of the second magnetic absorbent-containing resin-based composite material plate covers a frequency band of 2 GHz to 4 GHz, and glue and cure the upper panel (2), the sandwich structure core layer (1), and the lower panel (3) to obtain a composite sandwich structure with electromagnetic damage tolerance.

2. The method for preparing a composite sandwich structure with electromagnetic damage tolerance according to claim 1, characterized in that: In step S1, the mass of the dielectric absorbent filler is 7% to 20% of the total mass of the dielectric absorbent filler and the first resin, the mass of the first magnetic absorbent filler is 30% to 45% of the total mass of the first magnetic absorbent filler and the second resin, and the mass of the second magnetic absorbent filler is 50% to 60% of the total mass of the second magnetic absorbent filler and the third resin.

3. The method for preparing a composite sandwich structure with electromagnetic damage tolerance according to claim 1, characterized in that: In step S3, the thickness of the first magnetic loss layer (5) is 3 mm to 5 mm, the thickness of the second magnetic loss layer (6) is 2 mm to 4 mm, and the thickness of the third magnetic loss layer (7) is 2 mm to 3 mm.

4. The method for preparing a composite sandwich structure with electromagnetic damage tolerance according to any one of claims 1 to 3, characterized in that: In step S1, the dielectric absorbent filler includes one or more of chopped carbon fibers, carbon nanotubes, graphene, and carbon black, the average length of the chopped carbon fibers is 0.5 mm to 1.5 mm, the outer diameter of the carbon nanotubes is 40 nm to 60 nm, the particle size of the graphene is 40 nm to 60 nm, and the particle size of the carbon black is 40 nm to 60 nm; the first resin includes one or more of polyamide resin, polylactic acid resin, and polyethylene terephthalate; the first magnetic absorbent filler includes carbonyl iron, ferrite, One or more of an iron-cobalt alloy and an iron-nickel alloy, the particle size of the first magnetic absorbent filler is 10 μm to 50 μm, and the second resin includes one or more of a polyamide resin, a polylactic acid resin and polyethylene terephthalate; the second magnetic absorbent filler includes one or more of carbonyl iron, ferrite, an iron-cobalt alloy and an iron-nickel alloy, the particle size of the second magnetic absorbent filler is 10 μm to 50 μm, and the third resin includes one or more of a polyamide resin, a polylactic acid resin and polyethylene terephthalate.

5. The method for preparing a composite sandwich structure with electromagnetic damage tolerance according to any one of claims 1 to 3, characterized in that: In step S4, in the resin-based composite material plate containing glass fiber, the volume fraction of the glass fiber is 35% to 45%, and the resin includes one or more of epoxy resin, polyamide resin, polylactic acid resin and polyethylene terephthalate; in the resin-based composite material plate containing the second magnetic absorber, the mass fraction of the second magnetic absorber is 50% to 60%, and the resin includes one or more of polyamide resin, polylactic acid resin and polyethylene terephthalate.

6. The method for preparing a composite sandwich structure with electromagnetic damage tolerance according to any one of claims 1 to 3, characterized in that: In step S4, the thickness of the upper panel (2) is 1 mm to 1.5 mm, and the thickness of the lower panel (3) is 1 mm to 2 mm.

7. The method for preparing a composite sandwich structure with electromagnetic damage tolerance according to any one of claims 1 to 3, characterized in that: In step S4, the bonding is performed using epoxy resin E51 film, the curing temperature is 80° C. to 120° C., the pressure during the curing process is controlled at 0.1 MPa to 0.15 MPa, and the curing time is 1 hour to 2 hours.

8. A composite material sandwich structure with electromagnetic damage tolerance obtained by the method for preparing a composite material sandwich structure with electromagnetic damage tolerance according to any one of claims 1 to 7.

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