CN112635964B

CN112635964B - Slotted honeycomb wave-absorbing structure

Info

Publication number: CN112635964B
Application number: CN202011460703.4A
Authority: CN
Inventors: 陈海燕; 郏亚威; 孙启峰; 杨森; 邓龙江; 陆海鹏; 谢建良; 张丽; 周志鹏; 李小秋
Original assignee: University of Electronic Science and Technology of China
Current assignee: University of Electronic Science and Technology of China
Priority date: 2020-12-11
Filing date: 2020-12-11
Publication date: 2021-12-03
Anticipated expiration: 2040-12-11
Also published as: CN112635964A

Abstract

The invention belongs to the technical field of electronic materials, and particularly relates to a slotted honeycomb wave-absorbing structure. The invention provides a space for embedding an antenna, a radar and other electronic modules in a honeycomb structure by arranging n same irregular gaps in a periodic honeycomb structure, and realizes a design method based on honeycomb wave-absorbing structure embedding, namely, a honeycomb core is subjected to local hollowing treatment, a highly integrated electronic module is embedded in the core and subjected to protection design, so that the spacecraft design is qualitatively leap in the aspects of light weight and multiple functions. The key problem of the pre-buried design is that the electromagnetic/mechanical strength of the honeycomb structure after slotting is evaluated, so that the honeycomb structure not only reduces the weight of the honeycomb structure, but also has good electromagnetic/mechanical properties under a reasonable slotting method.

Description

Slotted honeycomb wave-absorbing structure

Technical Field

The invention belongs to the technical field of electronic materials, and particularly relates to a slotted honeycomb wave-absorbing structure.

Background

The honeycomb wave-absorbing structure has the characteristics of light weight, high specific strength, excellent impact resistance, excellent electromagnetic wave absorption capacity and the like, and can be used for forming various parts with complex shapes, such as wings, empennages, air inlet channels and the like, so that the honeycomb wave-absorbing structure is widely applied to the fields of aerospace, transportation and the like. The reduction of the quality of the spacecraft is one of the important targets of the modern aerospace technology, and particularly, the quality of the spacecraft is reduced by one order of magnitude on the existing basis, so that the aerospace technology in China is greatly developed.

The objective of multifunctional structural technology is to "perfect bond" passive electronic components to composite materials to integrate thermal, electronic, and radiation shielding functions into the inherent load bearing components of a spacecraft. In order to meet the multifunctional engineering application of the honeycomb wave-absorbing structure, relevant scholars externally connect a larger electronic device to the outside of a honeycomb, and the multifunctional application of the honeycomb structure is influenced due to the large volume of the device; some researchers also study the heat conduction function of the honeycomb after the metal honeycomb is slotted and an electronic element is placed in the metal honeycomb, but the metal honeycomb has large mass and has great application limitation under the requirement of light weight of an aircraft; and the design of the metal honeycomb is not favorable for the core technical purpose of wave absorption.

Therefore, how to realize the perfect combination of the honeycomb wave-absorbing structure and the electronic element in the actual engineering application process meets the engineering application requirements, and the honeycomb wave-absorbing structure has good wave-absorbing, mechanical and electromagnetic properties and has great significance.

Disclosure of Invention

Aiming at the problems or the defects, the invention provides the slotted honeycomb wave-absorbing structure in order to solve the problem that the existing honeycomb wave-absorbing structure cannot be well combined with an electronic element in practical engineering application, which not only meets the practical application, but also ensures that the honeycomb wave-absorbing structure has good performance in the electromagnetic/mechanical aspect, and provides a guiding function for the multifunctional design of the honeycomb structure.

The slotted honeycomb wave-absorbing structure comprises a bottom layer metal back plate and a periodic honeycomb structure above the bottom layer metal back plate, wherein the height of the whole periodic honeycomb structure is T, and the length in the L direction is L₀The length in the W direction is W₀And r is the length of the outer edge of the hexagonal honeycomb holes of the aramid paper honeycomb, and the height of the metal back plate is 0 by default, as shown in figure 1.

The periodic honeycomb structure is provided with n identical irregular gaps, and n is equal to L₀And (6 r) is odd and rounded downwards, and the ratio of the gaps to the whole periodic honeycomb structure is n L1 (W1+ W2)/(2L)₀*W₀) (ii) a The plane center of the periodic honeycomb structure is used as the plane center of the first irregular gap, the direction perpendicular to the metal back plate is used as the height direction of the irregular gap, the long side of the first irregular gap is parallel to the W side, and the wide side of the first irregular gap is parallel to the L side.

Taking the first irregular gap as a prototype, and arranging the rest n-1 irregular gaps in a manner of translation towards the L direction at two sides of the first irregular gap and bilateral symmetry, wherein the distances L2 between adjacent irregular gaps are equal, L2 is 6r-L1, and L2 is not less than 3r and not more than 5 r; the distance L3 between the irregular gap on the outermost side in the L direction and the edge of the periodic honeycomb structure is more than or equal to 3 r; the distance W3 between the outermost side of the W-direction irregular gap and the edge of the periodic honeycomb structure is more than or equal to W₀/2-3r。

The irregular gap is divided into an upper gap and a lower gap by the surface of the T/2 height of the periodic honeycomb structure, wherein the upper gap is far away from the metal back plate, the lower gap is close to the metal back plate, the upper gap and the lower gap are respectively rectangular spaces, the width and the height of the upper gap and the lower gap are the same, and the upper gap is positioned right above the lower gap; on the upper partThe length W1, width L1, and height T1 of the slot are T/2; a lower slot length W2, a width L1, a height T2-T/2-T1, wherein W₀/6≤W1≤5W₀/6，r≤L1≤3r，W1≤W2≤W₀-6r，r≤L1≤3r。

Furthermore, the hole wall of the periodic honeycomb structure is made of two layers of materials, the inner layer is aramid fiber paper honeycomb, and the outer layer is a wave-absorbing coating; the cross section of the aramid fiber paper honeycomb holes is in a regular hexagon shape, and the inner layer is made of a composite material made of aramid fiber paper and resin.

Furthermore, the pore wall of the periodic honeycomb structure is made of three layers of materials, the inner layer is the aramid fiber paper honeycomb, the outer layer is the wave-absorbing coating, the periodic honeycomb structure further comprises a reinforcing layer arranged between the aramid fiber paper honeycomb and the wave-absorbing coating, and the reinforcing layer enables the structural strength of the periodic honeycomb structure to be better.

Furthermore, the outer wave-absorbing coating of the periodic honeycomb structure is uniformly distributed in the honeycomb hole along the axial direction of the hexagonal prism.

The parameters for measuring the mechanical property of the honeycomb structure comprise peak force, flat-pressing elastic modulus, yield strength and platform stress. The peak force of the elastic stage is an important parameter for measuring the mechanical property of the honeycomb, represents the maximum load of the elastic stage, is larger than the peak force, cannot recover the deformation of the honeycomb, and starts to damage the honeycomb structure; the flat compression elastic modulus is the size of the honeycomb in resisting elastic deformation; the yield strength is the yield limit of the material when the material generates a yield phenomenon, and the material can lose efficacy when the material is subjected to an external force greater than the yield strength; the platform stress is the average stress of the honeycomb in the platform stage in the plastic folding process and is an important parameter for measuring the energy absorption effect of the honeycomb.

The structure of the invention adopts irregular slotting on the honeycomb wave-absorbing structure, and under the condition that the slotting is of the same width, when W1 is not more than W2 and W2 is kept unchanged, the change of W1 does not affect the peak value, the flat-pressing elastic modulus and the yield strength of the honeycomb structure; in the electromagnetic aspect, the RCS mean value is-33 dBm²In the following, the change of W1 does not affect the electromagnetic performance of the honeycomb, and the influence of irregular slits on the mechanical parameters of the honeycomb is consistent.

When the honeycomb seam length W1 is not less than W2 and W2 is kept unchanged, the change of W1 does not affect the peak value, the flat-pressing elastic modulus and the yield strength of the honeycomb structure, and the peak value, the elastic modulus and the yield strength of the irregular seam honeycomb are controlled by the layer with the largest seam length. The lower layer is provided with large slots and weak strength, and the lower layer is folded and deformed firstly, so that the elastic stage of the whole honeycomb is influenced, and the peak value, flat compression elastic modulus and yield strength of the slotted honeycomb are basically unchanged; after the lower layer is compressed and densified, the upper layer begins to deform and fold, the load is increased in a step shape, the step shape is more obvious when the width of the upper seam and the width of the lower seam are larger and the difference of the lengths of the seams is larger, and the step shape is beneficial to energy absorption. According to the slotted honeycomb wave-absorbing structure disclosed by the invention, after the upper layer slots are enlarged, the peak value, the flat-pressing elastic modulus and the yield strength are basically unchanged, the weight of the honeycomb can be reduced to meet the requirements of engineering application, and the multifunctional design of the honeycomb structure is realized.

Electromagnetically, the honeycomb is slotted in a manner consistent with that described above. When the slots are irregularly slotted, the change of W1 does not affect the electromagnetic performance of the honeycomb structure, RCS curves of the three slotted structures are basically overlapped, and the mean value of RCS is-33 dBm²This is consistent with the mechanical properties of the irregular slits of the honeycomb, the elastic phase, below. Therefore, the slotted honeycomb wave-absorbing structure provided by the invention not only has light weight, but also has no change in electromagnetic performance, still has good wave-absorbing performance, and is convenient for realizing multifunctional design of the honeycomb structure.

In summary, the invention provides a space for embedding an antenna, a radar and other electronic modules in a honeycomb structure through a specific honeycomb structure slotting method, and realizes a design method based on honeycomb wave-absorbing structure pre-embedding, namely, a honeycomb core is subjected to local hollowing treatment, a highly integrated electronic module is embedded in the core for protection design, so that the spacecraft design is qualitatively leap in the aspects of light weight and multiple functions. The key problem of the pre-buried design is that the electromagnetic/mechanical strength of the honeycomb structure after slotting is evaluated, so that the honeycomb structure not only reduces the weight of the honeycomb structure, but also has good electromagnetic/mechanical properties under a reasonable slotting method.

Drawings

FIG. 1 is a diagram illustrating the overall effect of the conventional honeycomb wave-absorbing structure of the embodiment;

FIG. 2 is a parameter diagram of the cross section of a honeycomb hole unit of the honeycomb wave-absorbing structure of the embodiment;

FIG. 3 is a diagram of the overall effect of the slotted honeycomb wave-absorbing structure in the embodiment;

FIG. 4 is a top view of the slotted honeycomb wave-absorbing structure of the embodiment;

FIG. 5 is a front view of the slotted honeycomb wave-absorbing structure of the embodiment;

FIG. 6 is a side view of the slotted honeycomb wave-absorbing structure of the embodiment;

fig. 7 is a graph of compressive load versus stroke for three slotted honeycomb configurations for the example L1 ═ r;

fig. 8 is a graph of compression load versus travel for three slotted honeycomb configurations for example L1 ═ 2 r;

fig. 9 is a graph of compression load versus travel for three slotted honeycomb configurations for the example L1 ═ 3 r;

fig. 10 is a plot of compressive load versus stroke for three slotted honeycomb configurations tested for example L1 ═ 2 r;

fig. 11 is a plot of RCS values for three slotted cells as a function of azimuth, for 8GHz, HH polarization, for example L1 ═ r;

fig. 12 is a plot of RCS values versus azimuth for three slotted cells, with 8GHz, VV polarization, for example L1 ═ r;

fig. 13 is a plot of RCS values for three slotted cells as a function of azimuth, for 8GHz, HH polarization, for example L1 ═ 2 r;

fig. 14 is a plot of RCS values for three slotted cells as a function of azimuth angle for an example L1 at 2r, 8GHz, VV polarization;

fig. 15 is a plot of RCS values for three slotted cells as a function of azimuth, for 8GHz, HH polarization, for example L1 ═ 3 r;

fig. 16 is a plot of RCS values for three slotted cells as a function of azimuth angle for 8GHz, VV polarization, and 3r for example L1.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples.

Example (b):

the specific size parameters of the slotted honeycomb wave-absorbing structure are (unit mm): r 1.83, t0 0.1, t1 0.0125, L1 r, 2r and 3r, and a lower slot length W2 5/6W 1₀W11, W12 and W13 are length values of three embodiments of the backstitch length W1, wherein W11 is 1/6W₀，W12＝1/2*W₀，W13＝5/6*W₀。

The hole wall of the honeycomb structure is provided with two layers of materials, the inner layer is aramid fiber paper honeycomb, and the outer layer is a wave-absorbing coating. The cross section of the aramid fiber paper honeycomb holes is in a regular hexagon shape, the inner layer is made of a composite material made of aramid fiber paper and resin, r is the outer edge length of the aramid fiber paper honeycomb hexagonal honeycomb holes, and t0 is the wall thickness of the aramid fiber paper honeycomb; the wave-absorbing coating is uniformly distributed in the honeycomb holes along the axial direction of the hexagonal prisms, and the thickness of the wave-absorbing coating is t1, as shown in figure 2.

The honeycomb shown in fig. 1 is slotted, and a first irregular slot (an upper slot is far away from the metal back plate, and a lower slot is close to the metal back plate) is formed at the plane center position of the honeycomb structure (the center of the slot is coincident with the center of the honeycomb). The irregular gap is divided into an upper gap and a lower gap by the T/2 height of the honeycomb structure, the upper gap and the lower gap are respectively a cuboid space, the width and the height of the upper gap and the lower gap are the same, the upper gap is positioned right above the lower gap, and the plane center of the irregular gap is superposed with the plane center of the honeycomb structure; upper seam open length W1 (W)₀/6≤W1≤5W₀/6), the slotting width L1(r is less than or equal to L1 and less than or equal to 3r), and the slotting height T1 is T/2; the length of the lower seam is W2(W1 is more than or equal to W2 is more than or equal to W₀-6r), a slit width L1(r ≦ L1 ≦ 3r), and a slit height T2 ═ T/2 ═ T1.

Taking the first irregular gap as a prototype, and arranging the rest n-1 irregular gaps in a manner of translating towards the L direction at two sides of the first irregular gap and realizing bilateral symmetry, wherein the distances L2 between the adjacent irregular gaps are equal, and L2 is 6r-L1, (3r is more than or equal to L2 is more than or equal to 5r, so as to ensure that the honeycomb between the gaps at least comprises one row of complete regular hexagon honeycomb units); the distance L3 between the irregular gap on the outermost side in the L direction and the edge of the periodic honeycomb structure is more than or equal to 3 r; outermost side of W-direction irregular gap and edge of periodic honeycomb structureDistance W3 is not less than W₀2-3 r; the irregular slotting diagrams are shown in fig. 3, 4, 5 and 6.

Through the irregular slits obtained through design, the mechanical property of the honeycomb after the slits are reduced under the compression simulation, but as can be seen through analysis of fig. 7, 8 and 9, the elastic stages of the three slit structures are basically coincident with the load-stroke curve of the front half part, and the peak value, the flat-pressing elastic modulus and the yield strength of the honeycomb structure are basically unchanged, which indicates that under the condition that the length of the slits of the lower layer is large, the change of the length of the slits of the upper layer does not influence the peak value, the elastic modulus and the yield strength. The load-stroke curve of the latter half part is reduced along with the increase of the upper layer slotting length, and when L1 is r, the platform stress change is small; when L1 is equal to 2r, the size difference of the upper and lower slits is gradually increased, and the stress change of the platform is large; when L1 is 3r, the difference in the sizes of the upper and lower slits is the largest, and the change in the platform stress is the largest.

Due to the fact that the size of the slot is small, the error of the upper and lower irregular slots of the same honeycomb is difficult to control in experiments, and therefore different slots are formed in the honeycomb with two layers, and experimental verification is conducted. Under the compression experiment, the honeycomb has no elastic stage, mainly the upper honeycomb and the lower honeycomb are embedded and deformed with each other, and no peak value exists, which is consistent with the result in the literature. The mechanical properties of the slotted honeycomb are reduced, but as can be obtained from fig. 10, the elastic phase of two slotted structures with L1_2r _ up _ W11_ down _ W2 and L1_2r _ up _ W12_ down _ W2 is basically coincident with the load-stroke curve of the first half, and the peak value, the flat-compression elastic modulus and the yield strength are basically unchanged. After the honeycomb with the large length of the lower layer of the slot is densified, the slot of the upper layer of the honeycomb is deformed and folded, and the load-stroke curve of the latter half part is reduced along with the increase of the length of the slot, which is consistent with the simulation result.

By irregular slotting of the design, HH polarization was observed under electromagnetic simulation, as in fig. 11, 13, and 15; VV polarization, as shown in fig. 12, 14 and 16, the RCS curves for the three slotted honeycomb structures substantially coincide, indicating that irregular slots have no effect on the wave absorption performance of the honeycomb. The irregular slotted honeycomb structure not only meets engineering application, but also has unchanged electromagnetic performance and RCSThe value is-33 dBm²The honeycomb structure has better wave-absorbing performance and can realize multifunctional design of the honeycomb structure.

Through the experimental analysis, the slotted honeycomb wave-absorbing structure designed by the invention has the advantages that when the slotted length W1 of the honeycomb is not more than W2 and W2 is not changed, the peak value, the flat-pressing elastic modulus and the yield strength of the honeycomb structure are not influenced by the change of W1, and the peak value, the elastic modulus and the yield strength of the irregular slotted honeycomb are controlled by the layer with the largest slotted length. Because the lower layer is provided with a large seam and weak strength, the lower layer is folded and deformed, so that the elastic stage of the whole honeycomb is influenced; after the lower layer is compressed and densified, the upper layer begins to deform and fold; the load has a step-shaped rise, the larger the width of the upper seam and the lower seam is, the larger the difference of the lengths of the seams is, the more obvious the step-shaped rise is, and the step-shaped rise is beneficial to energy absorption.

Electromagnetically, the honeycomb is slotted in a manner consistent with that described above. When the slots are irregularly slotted, the electromagnetic performance of the honeycomb structure is not influenced by the change of W1, RCS curves of the three slotted structures are basically overlapped under HH polarization and VV polarization, and the mean value of RCS is-33 dBm²The following. The irregular slotting of the invention ensures that after the honeycomb is slotted, not only the weight is reduced and the engineering application is satisfied, but also the peak value of mechanical parameters, the flat compression elastic modulus, the yield strength and the RCS value are not changed, still has better electromagnetic/mechanical properties, and is convenient to realize the multifunctional design of the honeycomb structure.

In conclusion, the slotted honeycomb wave-absorbing structure provided by the invention solves the problem that the existing honeycomb wave-absorbing structure cannot be well combined with an electronic element in practical engineering application, not only meets the practical application, but also ensures that the honeycomb wave-absorbing structure has good performance in the electromagnetic/mechanical aspect, and provides a guiding function for the multifunctional design of the honeycomb structure.

Claims

1. The utility model provides a crack honeycomb absorbent structure, includes the periodic honeycomb structure of bottom metal backplate and its top, its characterized in that:

the height of the whole periodic honeycomb structure is T, and the length of the whole periodic honeycomb structure in the L direction is L₀The length in the W direction isW₀(ii) a The height of the metal back plate is 0 by default, and r is the length of the outer edge of the hexagonal honeycomb holes of the aramid paper honeycomb;

the periodic honeycomb structure is provided with n identical irregular gaps, and n is equal to L₀And (6 r) is odd and rounded downwards, and the ratio of the gaps to the whole periodic honeycomb structure is n L1 (W1+ W2)/(2L)₀*W₀) (ii) a Taking the plane center of the periodic honeycomb structure as the plane center of the first irregular gap, taking the direction vertical to the metal back plate as the height direction of the irregular gap, wherein the long side of the first irregular gap is parallel to the W side, and the wide side of the first irregular gap is parallel to the L side;

taking the first irregular gap as a prototype, and arranging the rest n-1 irregular gaps in a manner of translation towards the L direction at two sides of the first irregular gap and bilateral symmetry, wherein the distances L2 between adjacent irregular gaps are equal, L2 is 6r-L1, and L2 is not less than 3r and not more than 5 r; the distance L3 between the irregular gap on the outermost side in the L direction and the edge of the periodic honeycomb structure is more than or equal to 3 r; the distance W3 between the outermost side of the W-direction irregular gap and the edge of the periodic honeycomb structure is more than or equal to W₀/2-3r；

The irregular gap is divided into an upper gap and a lower gap by the surface of the T/2 height of the periodic honeycomb structure, wherein the upper gap is far away from the metal back plate, the lower gap is close to the metal back plate, the upper gap and the lower gap are respectively rectangular spaces, the width and the height of the upper gap and the lower gap are the same, and the upper gap is positioned right above the lower gap; the length W1, the width L1 and the height T1 of the upper seam are T/2; a lower slot length W2, a width L1, a height T2-T/2-T1, wherein W₀/6≤W1≤5W₀/6，r≤L1≤3r，W1≤W2≤W₀-6r；

The hole wall of the periodic honeycomb structure is made of two layers of materials, the inner layer is aramid fiber paper honeycomb, and the outer layer is a wave-absorbing coating; or three layers of materials, wherein the inner layer is the aramid fiber paper honeycomb, the outer layer is the wave-absorbing coating, and the reinforced layer is arranged between the aramid fiber paper honeycomb and the wave-absorbing coating.

2. The slotted honeycomb wave-absorbing structure of claim 1, wherein: the cross section of the aramid fiber paper honeycomb holes is in a regular hexagon shape, and the inner layer is made of a composite material made of aramid fiber paper and resin.

3. The slotted honeycomb wave-absorbing structure of claim 1, wherein: the outer wave-absorbing coating of the periodic honeycomb structure is uniformly distributed in the honeycomb hole along the axial direction of the hexagonal prism.