Imitation screw electromagnetic wave absorber based on 4D printing and additive manufacturing method thereof

Abstract

The invention belongs to the technical field of electromagnetic metamaterials, and particularly discloses a screw-imitating electromagnetic wave absorber based on 4D printing and an additive manufacturing method thereof.The screw-imitating electromagnetic wave absorber comprises a plurality of unit cell structures which are formed through 3D printing and are in a periodic array, and each unit cell structure comprises a planar substrate and a screw-imitating wave absorbing structure; all the planar substrates form a bottom supporting area, all the imitated-screw wave-absorbing structures form a threaded wave-absorbing functional area, each imitated-screw wave-absorbing structure comprises a first screw, the first screws are vertically arranged on the planar substrates, the size of the cross section of each first screw is gradually reduced from the bottom to the top, and the outer sides of the first screws are wound in the axial direction to form external threaded protrusions; the planar substrate has a shape memory characteristic and recovers its initial form over time in a predetermined temperature environment. Electromagnetic parameter gradient distribution is optimized through bionic screw structure design, the multi-material 4D printing technology is combined to integrate broadband wave absorption and shape memory functions, and the electromagnetic metamaterial is promoted to develop towards multifunctional integration.

Description

Technical Field

[0001] This application belongs to the field of electromagnetic metamaterials technology, and more specifically, relates to a screw-like electromagnetic absorber based on 4D printing and its additive manufacturing method. Background Technology

[0002] In the field of modern electromagnetic protection, the demand for "wideband, wide-angle, strong absorption, and dynamic controllability" electromagnetic absorbing materials for specialized equipment and electronic devices is becoming increasingly urgent. Traditional electromagnetic absorbing materials (such as ferrite and carbonyl iron-based materials) are limited by a single loss mechanism and a simple flat / stacked structure design, resulting in a narrow effective absorption bandwidth (EAB), making it difficult to cover the electromagnetic environment of multi-band network detection. At the same time, their static structure cannot respond to external stimuli (such as temperature) to achieve adjustable absorption performance, and their ability to adapt to complex application scenarios is weak.

[0003] While metastructure absorbers (MMAs) have improved their absorption performance through subwavelength periodic structure optimization, traditional fabrication processes (such as screen printing and etching) are complex, making it difficult to achieve integrated molding of complex three-dimensional structures. Furthermore, they often utilize single materials (such as purely conductive coatings and honeycomb substrates), resulting in high bulk density and significant anisotropy, which limits their engineering applications. Existing 3D-printed MMA solutions (such as octagonal lattice structures and carbonyl iron / PEEK gradient structures) improve manufacturing flexibility, but still suffer from limitations such as limited structural configurations (primarily stacked and lattice-based) and a lack of adaptive deformation capabilities, failing to meet the integrated requirement of "electromagnetic absorption-dynamic adaptation." Summary of the Invention

[0004] In response to the deficiencies or improvement needs of existing technologies, this application provides a screw-like electromagnetic absorber based on 4D printing and its additive manufacturing method, aiming to solve the technical problems of the single structural configuration and lack of adaptive deformation capability of electromagnetic absorbers in the prior art.

[0005] This application provides a 4D-printed imitation screw electromagnetic absorber, which includes multiple periodically arrayed unit cell structures formed by 3D printing. Each unit cell structure includes a planar substrate and an imitation screw absorbing structure. All planar substrates form a bottom support area, and all imitation screw absorbing structures form a threaded absorbing functional area. The imitation screw absorbing structure includes a first screw, which is vertically disposed on the planar substrate and has a cross-sectional dimension that gradually decreases from bottom to top. The outer side of the first screw has an external threaded protrusion coiled axially. The planar substrate has shape memory characteristics and can recover its initial shape over time under a predetermined temperature environment.

[0006] As a further preferred embodiment, the planar substrate has a rectangular structure, and the plurality of the unit cell structures are distributed in a rectangular array.

[0007] As a further preferred embodiment, the planar substrate has a square structure, and the planar substrate and the imitation screw wave-absorbing structure are integrally formed by 3D printing. The number of thread turns M of the first screw is 3 to 6, the pitch is 3 mm, the draft angle α is 0 to 18°, and the side length L of the planar substrate is 9 to 18 mm.

[0008] As a further preferred embodiment, the first screw has 6 thread turns M, a draft angle α of 12°, and a side length L of 15mm.

[0009] As a further preferred embodiment, the simulated screw absorbing structure further includes a second screw unit, which is formed at the four vertices of the planar substrate. When the four unit cell structures are combined in a 2*2 rectangular array, the four second screw units in the middle of the combined structure are assembled to form a second screw.

[0010] As a further preferred embodiment, the planar substrate is made of CB / TPU-PLA composite wire composed of 10 wt% CB, 18 wt% TPU, and 72 wt% PLA; the imitation screw absorbing structure is made of CB / PLA composite wire composed of 15 wt% CB and 85 wt% PLA.

[0011] As a further preferred embodiment, a tapered hole is formed at the top of the first screw, with the apex of the tapered hole located near the bottom of the first screw.

[0012] This application also provides an additive manufacturing method for a screw-like electromagnetic absorber, used to prepare the aforementioned screw-like electromagnetic absorber. Specifically, the additive manufacturing method involves simultaneously printing a planar substrate and a screw-like absorbing structure using FDM dual-nozzle 3D printing technology, based on the established screw-like single-cell structure and periodic array model.

[0013] As a further preferred option, the following steps are included: S1. Establish a three-dimensional model of the screw-like unit cell structure; S2. Generate a periodic array model according to the set array method; S3. Import the periodic array model into the FDM printing slicing software and set the printing parameters; S4. Using an FDM dual-nozzle 3D printer, print the planar substrate 11 and the imitation screw absorbing structure 12 layer by layer according to the slicing path planned by the FDM printing slicing software, thereby obtaining the imitation screw electromagnetic absorber.

[0014] As a further preferred embodiment, the FDM dual-nozzle 3D printer includes a first nozzle for printing planar substrates and a second nozzle for printing screw-like microwave absorbing structures. The printing parameters of the first nozzle are set as follows: layer thickness 0.1-0.2 mm, printing speed 15-45 mm / s, nozzle temperature 215-230℃, and heated bed temperature 65℃. The printing parameters of the second nozzle are set as follows: layer thickness 0.1-0.2 mm, printing speed 20-50 mm / s, and nozzle temperature 200-220℃.

[0015] In summary, compared with the prior art, the technical solutions conceived in this application have the following main technical advantages: 1. The screw-like electromagnetic absorber of this application innovatively adopts multiple periodically arrayed unit cell structures, each unit cell consisting of a planar substrate and a screw-like absorbing structure. The screw-like absorbing structure includes a first screw with a bottom dimension larger than the top dimension and an externally threaded protrusion coiled axially on the outside. This breaks the limitations of traditional structures, providing a completely new structural configuration for electromagnetic absorbers and enriching the design possibilities of absorbers. The planar substrate changes its shape over time under a predetermined temperature environment, allowing the electromagnetic absorber to adaptively deform according to changes in external temperature, thereby changing its electromagnetic properties to adapt to different electromagnetic environments. Compared with traditional static electromagnetic absorbing materials, this absorber can better respond to external stimuli, enhance its ability to adapt to complex application scenarios, and achieve a wider effective absorption bandwidth and superior wide-angle absorption characteristics.

[0016] 2. Multi-material integrated molding is achieved through dual-nozzle FDM technology, eliminating the need for subsequent assembly. The process is simple, low-cost, and can be mass-produced, with significant lightweight characteristics. 3. In the planar substrate material, CB ensures conductivity, TPU provides shape memory capability, and the matrix ensures load-bearing capacity, so that the substrate has both low dielectric loss and thermally driven shape memory characteristics, which meets the requirements of dynamic deformation of superstructures. Attached Figure Description

[0017] Figure 1 This is a three-dimensional structural diagram of a screw-like electromagnetic absorber based on 4D printing provided in an embodiment of the present invention; Figure 2 This is a three-dimensional structural diagram of a unit cell structure in a 4D-printed imitation screw electromagnetic absorber provided in an embodiment of the present invention. Figure 3 This is a side view of a unit cell structure in a 4D-printed imitation screw electromagnetic absorber provided in an embodiment of the present invention; Figure 4 This is a top view of a unit cell structure in a 4D-printed, screw-like electromagnetic absorber provided in an embodiment of the present invention; Figure 5 This is a cross-sectional view of a unit cell structure in a 4D-printed imitation screw electromagnetic absorber provided in an embodiment of the present invention; Figure 6 This is a schematic diagram illustrating the fabrication of a screw-like electromagnetic absorber based on 4D printing, provided in an embodiment of the present invention. Figure 7 This is a graph showing the effective absorption bandwidth variation of a 4D-printed imitation screw electromagnetic absorber with an incident angle of 0-60°, provided in an embodiment of the present invention. Figure 8 This is a frequency-reflectivity curve obtained from an arc-shaped method experiment using a 4D-printed, screw-like electromagnetic absorber, as provided in an embodiment of the present invention. Figure 9 This invention provides an embodiment of a 4D-printed, screw-like electromagnetic absorber that undergoes shape recovery over time in a constant-temperature water bath.

[0018] In the picture: 10. Unit cell structure; 11. Planar substrate; 12. Screw-like wave-absorbing structure; 121. First screw; 122. External thread protrusion; 123. Second screw unit; 124. Second screw. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0020] This embodiment provides a 4D-printed imitation screw electromagnetic absorber, which includes multiple periodically arrayed unit cell structures 10 formed by 3D printing. Each unit cell structure 10 includes a planar substrate 11 and an imitation screw absorbing structure 12. All planar substrates 11 form a bottom support area 10a, and all imitation screw absorbing structures 12 form a threaded absorbing functional area 10b. The imitation screw absorbing structure 12 includes a first screw 121, which is vertically disposed on the planar substrate 11 and has a bottom dimension larger than its top dimension. An external thread protrusion 122 is formed on the outer side of the first screw 121 along the axial direction. The planar substrate 11 has shape memory characteristics and can recover its initial shape over time under a predetermined temperature environment.

[0021] 4D printing technology refers to the ability of structures printed by 3D printing technology to change shape or structure under external stimuli, directly embedding the deformation design of materials and structures into the material. That is, the printed product changes shape or state over time in a specific external environment. In this application, a planar substrate 11 with shape memory characteristics is directly obtained by 3D printing, and the planar substrate 11 can recover its initial shape over time under a predetermined temperature environment, thus constituting a screw-like electromagnetic absorber based on 4D printing.

[0022] The aforementioned predetermined temperature environment is 65~90℃, which covers the operating temperature of the electromagnetic absorber and can meet the usage requirements.

[0023] Preferably, the planar substrate 11 has a rectangular structure, and the multiple unit cell structures 10 are distributed in a rectangular array. More preferably, the planar substrate 11 has a square structure, and the planar substrate and the screw-like microwave absorbing structure are integrally formed by 3D printing. The number of thread turns M of the first screw 121 is 3 to 6, the pitch is 3 mm, the draft angle α of the screw-like microwave absorbing structure is 0 to 18°, and the side length L of the planar substrate 11 is 9 to 18 mm.

[0024] In a preferred embodiment of this application, the number of thread turns M of the first screw 121 is 6, which effectively controls the number of resonance peaks and low-frequency absorption coverage; the draft angle α is 12°, which optimizes the radial electromagnetic parameter gradient and improves impedance matching; the side length L is 15mm, which affects the spatial period and electromagnetic wave diffraction characteristics; and the pitch is fixed at 3mm to ensure the stability of the thread structure and the consistency of electromagnetic resonance.

[0025] In some optional embodiments of this application, the first screw 121 has 3 thread turns M, a draft angle of 18°, and a side length L of the planar substrate 11 of 9 mm. In other optional embodiments of this application, the first screw 121 has 5 thread turns M, a draft angle of 0°, and a side length L of the planar substrate 11 of 18 mm.

[0026] In a preferred embodiment of this application, the simulated screw absorbing structure 12 further includes a second screw unit 123. The second screw unit 123 is formed at the four vertices of the planar substrate 11. When the four unit cell structures 10 are combined in a 2*2 rectangular array, the four second screw units 123 are assembled in the middle of the combined structure to form a second screw 124.

[0027] It is understood here that the assembly of four second screw units 123 to form a second screw 124 does not mean that the four second screw units 123 are individually formed and then assembled together to form the second screw 124 during manufacturing. This statement is only for the convenience of determining the unit cell structure of the simulated screw electromagnetic absorber, and to make the simulated screw electromagnetic absorber directly formed by rectangular array of unit cell structure, which is convenient for three-dimensional modeling and simplifies the modeling process.

[0028] In the embodiments of this application, the material used to manufacture the planar substrate is a CB / TPU-PLA composite wire composed of 10 wt% CB (carbon black), 18 wt% TPU (thermoplastic polyurethane), and 72 wt% PLA (polylactic acid), by weight percentage.

[0029] The CB / TPU-PLA composite filament is a self-made filament. First, the prepared raw material powder is mixed in a ball mill according to the ratio and mixed evenly. After that, the parameters of the filament extrusion molding machine are set, and the mixed powder is added to the single screw filament extrusion molding machine in batches. The diameter of the filament after extrusion is controlled according to the 3D printer usage standard. The filament is then cooled in a water bath to obtain the self-made composite filament. In the embodiment of this application, the filament diameter is controlled within the range of 2.80~2.90 mm to adapt to the corresponding 3D printer equipment.

[0030] In this composite wire, carbon black (CB) is uniformly dispersed in the form of CB particles. The main function of the CB particles is to conduct electricity. Thermoplastic polyurethane (TPU) provides the material with shape memory capabilities. Specifically, thermoplastic polyurethane is cross-linked by intermolecular hydrogen bonds or by slight cross-linking between macromolecular chains. These two cross-linking structures are reversible as the temperature rises or falls. In the molten or solution state, the intermolecular forces weaken, but after cooling or solvent evaporation, strong intermolecular forces reconnect them, restoring the original solid properties, thus achieving the purpose of changing form over time under different temperature environments. PLA (polylactic acid) serves as the material matrix, ensuring the stability of the material. Carbon black (CB), TPU, and PLA are commercially available materials that can be purchased directly from the market.

[0031] The material used to fabricate the screw-like microwave absorbing structure is a CB / PLA composite wire composed of 15 wt% CB and 85 wt% PLA. Since the screw-like microwave absorbing structure does not require a corresponding morphological change due to temperature, CB (carbon black) is uniformly dispersed in the CB / PLA composite wire in the form of CB particles. Its main function is dielectric loss (conductivity loss, interface polarization loss), which is responsible for dissipating the energy of the incident electromagnetic wave. The CB / PLA composite wire serves as the material matrix, ensuring the stability of the material.

[0032] In a preferred embodiment of this application, a tapered hole 12a is formed on the top of the first screw 121, and the apex of the tapered hole 12a is located near the bottom of the first screw 121. The tapered hole 12a can effectively reduce the weight of the electromagnetic absorber and also give the electromagnetic absorber better impedance and better absorption performance.

[0033] As a preferred electromagnetic organelle structure, the top radius of the first screw 121 is R, the radius of the second screw 124 is r, the top opening diameter of the conical hole 12a is D, the depth of the conical hole 12a is T, the height of the screw-like wave-absorbing structure 12 is H, the height of the planar substrate 11 is h, and the side length of the planar substrate 11 is L, and the number of thread turns of the first screw 121 is M, as previously mentioned. These parameters satisfy the following structural relationship: R=(L-1) / 2……………………………………(1) r=R / 2……………………………………(2) D=2(RH*tanα-1)…………………………(3) T=0.9H……………………………………(4) h=0.1H………………………………………………(5) In addition, since the pitch is fixed at 3mm, H=3M.

[0034] Actual testing showed that the effective absorption bandwidth of the electromagnetic absorber in the 2-40 GHz frequency band was 36.95 GHz (3.05-40 GHz), and the minimum reflection loss was... 33.26 dB, with an effective absorption bandwidth of ≥34.66 GHz at an incident angle θ of 0-60°.

[0035] This application also provides an additive manufacturing method for a screw-like electromagnetic absorber, used to prepare the aforementioned screw-like electromagnetic absorber. Specifically, the additive manufacturing method involves simultaneously printing a planar substrate and a screw-like absorbing structure using FDM dual-nozzle 3D printing technology, based on an established screw-like unit cell structure and periodic array model.

[0036] By directly creating a periodic array using a screw-like unit cell structure model, a complete 3D model of the screw-like electromagnetic absorber can be obtained. Then, the planar substrate and the screw-like absorber structure are simultaneously printed using FDM (Fused Deposition Modeling) dual-nozzle printing technology. This fabrication method can achieve integrated molding of multiple materials without subsequent assembly. The process is simple, low-cost, and can be mass-produced with significant lightweight characteristics.

[0037] Specifically, the additive manufacturing method includes the following steps: S1. Establish a three-dimensional model of the screw-like unit cell structure; specifically, CAD, SolidWorks, or other 3D modeling software can be used to establish the three-dimensional model of the screw-like unit cell structure. S2. Generate a periodic array model according to the set array method; in this embodiment, a complete periodic array model is formed according to a 12*12 rectangular array imitating a screw unit cell structure.

[0038] S3. Import the periodic array model into the FDM printing slicing software and set the printing parameters; As in the embodiments of this application, the FDM printing slicing software used is UltiMaker Cura. After importing the periodic array model and setting the printing parameters, the software will automatically slice the model and plan the slicing path, and output a file containing the slicing path. This file can be directly imported into the corresponding 3D printer. In some embodiments, this file can also be transferred to the 3D printer for printing by default. It is understood that the FDM printing slicing software used will vary depending on the brand or type of 3D printer used. For example, in other embodiments, the FDM printing slicing software can also be Bambu Studio.

[0039] S4. Using an FDM dual-nozzle 3D printer, print the planar substrate and the imitation screw-like microwave absorbing structure layer by layer according to the slicing path planned by the FDM printing slicing software. After cooling, remove them from the printing platform.

[0040] As in the embodiments of this application, corresponding to the FDM printing slicing software, the FDM dual-nozzle 3D printer uses the Ultimaker dual-nozzle FDM printer from a certain brand, which has a first nozzle for printing planar substrates and a second nozzle for printing imitation screw absorbing structures. The printing parameters of the first nozzle are set as follows: layer thickness 0.1~0.2mm, printing speed 15-45mm / s, nozzle temperature 215-230℃, and heated bed temperature 60~70℃; the printing parameters of the second nozzle are set as follows: layer thickness 0.1-0.2mm, printing speed 20-50mm / s, and nozzle temperature 200-220℃.

[0041] In a preferred embodiment, the printing parameters of the first nozzle are set to a layer thickness of 0.1 mm, a printing speed of 25 mm / s, a nozzle temperature of 225°C, and a heated bed temperature of 65°C; the printing parameters of the second nozzle are set to a layer thickness of 0.1 mm, a printing speed of 35 mm / s, and a nozzle temperature of 210°C. Then, the planar substrate and the screw-like microwave absorbing structure are printed layer by layer according to the slicing path. During the printing process, the interface between the bottom support area and the threaded microwave absorbing functional area is naturally integrated. After printing is completed, the product can be removed from the printing platform after cooling.

[0042] The above electromagnetic absorber was tested in a microwave anechoic chamber using a Keysight N5224B vector network analyzer and the bow-shaped method. The results are as follows: Figure 8 As shown, its broadband absorption performance is as follows: RL≤ in the 3.05-40GHz frequency band. 10 dB, effective absorption bandwidth 36.95 GHz, minimum reflection loss value 33.26 dB (corresponding to a frequency of 10.66 GHz).

[0043] The wide-angle absorption performance is as follows: the effective absorption bandwidth is greater than 34.66 GHz when the incident angle θ varies from 0 to 60°. After being tested in a constant temperature water bath at 65~90℃, the shape memory performance is as follows: after the initial bending angle at both ends of the bottom support area is bent to 154°, it recovers to 153° in 2 seconds, 137° in 4 seconds, 128° in 6 seconds, 89° in 8 seconds, 66° in 10 seconds, recovers to 33° within 12 seconds, has a recovery rate of 92% in 30 seconds, and fully recovers to 0° in 40 seconds, with a deformation recovery rate of 100%.

[0044] In summary, by changing the shape of the planar substrate under different temperature environments over time, the electromagnetic absorber can adaptively deform according to changes in external temperature. The electromagnetic parameter gradient distribution is optimized through biomimetic screw structure design, and broadband absorption and shape memory functions are integrated by combining multi-material 4D printing technology to achieve strong absorption with a wide frequency range (2.68-40 GHz) and a wide angle (0-60°). At the same time, it has the ability to dynamically deform under heat, thus promoting the development of electromagnetic metamaterials towards multifunctional integration.

[0045] It should be understood that expressions such as "comprising" and "may include" as used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "comprising" and / or "having" may be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or combination thereof, but should not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0046] It should be understood that the terms “center,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0047] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0048] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0049] Those skilled in the art will readily understand that the above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A screw-like electromagnetic absorber based on 4D printing, characterized in that, The screw-like electromagnetic absorber includes multiple periodically arrayed unit cell structures (10) formed by 3D printing. Each unit cell structure (10) includes a planar substrate (11) and a screw-like absorbing structure (12). All the planar substrates (11) form a bottom support area, and all the screw-like absorbing structures (12) form a threaded absorbing functional area. The screw-like absorbing structure (12) includes a first screw (121). The first screw (121) is vertically arranged on the planar substrate (11) and its cross-sectional size gradually decreases from bottom to top. The outer side of the first screw (121) is axially coiled to form an external thread protrusion (122). The planar substrate (11) has shape memory characteristics and can recover its initial shape over time under a predetermined temperature environment.

2. The screw-like electromagnetic absorber according to claim 1, characterized in that, The planar substrate (11) has a rectangular structure, and the multiple unit cell structures (10) are distributed in a rectangular array.

3. The screw-like electromagnetic absorber according to claim 2, characterized in that, The planar substrate (11) has a square structure. The planar substrate (11) and the imitation screw wave-absorbing structure (12) are integrally formed by 3D printing. The first screw (121) has 3 to 6 threads M, a pitch of 3 mm, a draft angle α of 0 to 18°, and a side length L of 9 to 18 mm.

4. The screw-like electromagnetic absorber according to claim 3, characterized in that, The first screw (121) has 6 thread turns M, a draft angle α of 12°, and a side length L of 15mm.

5. The screw-like electromagnetic absorber according to claim 3, characterized in that, The simulated screw absorbing structure (12) also includes a second screw unit (123). The second screw unit (123) is formed at the four vertices of the planar substrate (11). When the four unit cell structures (10) are combined in a 2*2 rectangular array, the four second screw units (123) in the middle of the combined structure are spliced ​​together to form a second screw (124).

6. The screw-like electromagnetic absorber according to claim 1, characterized in that, The planar substrate (11) is made of CB / TPU-PLA composite wire composed of 10 wt% CB, 18 wt% TPU and 72 wt% PLA; the imitation screw absorbing structure (12) is made of CB / PLA composite wire composed of 15 wt% CB and 85 wt% PLA.

7. The screw-like electromagnetic absorber according to claim 1, characterized in that, The first screw (121) has a tapered hole at its top, with the apex of the tapered hole located near the bottom of the first screw (121).

8. An additive manufacturing method for a screw-like electromagnetic absorber, used to prepare the screw-like electromagnetic absorber as described in any one of claims 1-7, characterized in that, The additive manufacturing method specifically involves simultaneously printing a planar substrate (11) and a screw-like electromagnetic absorber (12) based on the established single-cell structure (10) and periodic array model of the simulated screw electromagnetic absorber using FDM dual-nozzle 3D printing technology.

9. The additive manufacturing method according to claim 8, characterized in that, Includes the following steps: S1. Establish a three-dimensional model of the unit cell structure (10); S2. Generate a periodic array model according to the set array method; S3. Import the periodic array model into the FDM printing slicing software and set the printing parameters; S4. Using an FDM dual-nozzle 3D printer, print the planar substrate (11) and the imitation screw absorbing structure (12) layer by layer according to the slicing path planned by the FDM printing slicing software, thereby obtaining the imitation screw electromagnetic absorber.

10. The additive manufacturing method according to claim 9, characterized in that, The FDM dual-nozzle 3D printer includes a first nozzle for printing a planar substrate (11) and a second nozzle for printing a screw-like microwave absorbing structure (12). The printing parameters of the first nozzle are set as follows: layer thickness 0.1-0.2 mm, printing speed 15-45 mm / s, nozzle temperature 215-230℃, and heated bed temperature 60-70℃. The printing parameters of the second nozzle are set as follows: layer thickness 0.1-0.2 mm, printing speed 20-50 mm / s, and nozzle temperature 200-220℃.

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