Bending test piece of grid panel low-density aluminum honeycomb core sandwich structure and preparation process

Abstract

The present invention provides a bending test piece of a grid panel low-density aluminum honeycomb core sandwich structure and a preparation process, including: optimizing relevant parameters of the test piece and preparing a grid panel blank according to the optimized parameters; adopting the method of instantaneously heating the whole adhesive film and applying hot air in the reverse direction to make the concave adhesive film bulge upward, break and shrink and gather at the end faces of the honeycomb core cell walls, forming a grid-shaped adhesive film with a uniform surface morphology; assembling the upper panel of the grid panel, the lower panel of the grid panel and the processed honeycomb core into one body, and curing by heating and pressurizing under vacuum conditions to obtain a bending test piece of a grid panel low-density aluminum honeycomb core sandwich structure. The process of the present invention omits the local strengthening and load equalization treatments such as step-by-step surface pasting of glass fiber cloth before testing, simplifies the testing process, improves the production efficiency of model development, the bending test failure parts of the bending test piece are uniform and stable, the test data dispersion is small, and the test results meet the requirements of design and use indicators.

Description

Technical Field

[0001] The present invention belongs to the technical field of manufacturing grid panel composite materials, and particularly relates to a bending test piece of a grid panel low-density aluminum honeycomb core sandwich structure and a preparation process thereof. Background Technique

[0002] The rigid solar wing substrates of each satellite platform are usually composed of an ultra-low-density aluminum honeycomb core adhesively bonded with two layers of high-modulus carbon fiber orthogonal grid panels. The ultra-low-density aluminum honeycomb core generally selects a weak-stiffness aluminum honeycomb core with the specification of CRIII-3 / 8-5056-.0007P-1.0 produced by the American company Hexcel (or PAMG-XR1-1.0-3 / 8-0.0007P-5056 produced by the company Plascore). This type of aluminum honeycomb core is prepared with an ultra-thin 5056 aluminum foil with a thickness of only 18 μm. The core cell size (the inscribed circle diameter of the core cell) reaches 9.52 mm, and the bulk density is 16 kg / m 3 , which is one of the lightest commercially available aluminum honeycomb cores in the world. During the service process of the solar wing substrate, it mainly bears bending loads. Evaluating the performance of the scaled-down parts can reflect the overall performance of the full-size substrate to a certain extent. To evaluate the bonding and mechanical properties of the orthogonal grid solar wing substrate, usually, a bending test piece of a grid panel low-density aluminum honeycomb core sandwich structure is prepared along with the product for three-point bending stiffness and four-point bending strength tests, and the comprehensive performance of the full-size solar wing substrate is evaluated according to the test results.

[0003] Currently, the bending test piece of the grid sandwich structure of the solar wing substrate usually forms a sandwich structure with two single-layer carbon fiber grid panels (the grid spacing is a×b, and the grid spacing is consistent with the grid parameters of the solar wing substrate product) and an aluminum honeycomb core with an outer dimension of L600 mm×W55 mm, and then conducts a bending test. In the actual implementation process, it is found that this method has the following disadvantages and deficiencies:

[0004] (1) In order to reduce the local stress concentration of the aluminum honeycomb core by the test loading indenter, it is necessary to perform local strengthening and load equalization treatment measures on the grid panel in the loading area, such as step-by-step surface pasting of fiberglass cloth, to avoid abnormal premature failure caused by local stress concentration of the test piece. This treatment measure is troublesome to operate and increases the development cycle of the test piece.

[0005] (2) Although local strengthening and load equalization treatment are performed on the grid panel in the loading area, since only 5 complete honeycomb core cells can be accommodated in the 55 mm width direction of the scaled-down part, the test edge effect is significant, manifested as poor consistency of the failure parts in the test results and large fluctuations in the test data. Summary of the Invention

[0006] In order to overcome the deficiencies in the prior art, the present inventor has conducted intensive research and provided a bending test piece of a grid panel low-density aluminum honeycomb core sandwich structure and a preparation process, which overcomes the problems that the existing solar wing substrate needs to be subjected to complex local strengthening treatments such as stepped surface mounting before testing, and the failure parts of the test results have poor consistency and large data fluctuations.

[0007] The technical solution provided by the present invention is as follows:

[0008] In the first aspect, a preparation process of a bending test piece of a grid panel low-density aluminum honeycomb core sandwich structure includes the following steps:

[0009] Determine the outer shape size, grid panel grid spacing parameter, and tow width parameter of the grid panel aluminum honeycomb core sandwich structure bending test piece according to the design parameters of the full-size solar wing substrate;

[0010] According to the determined grid spacing parameter and tow width parameter, use the fiber impregnated or coated with resin to perform orthogonal winding on the winding machine; remove the wound grid panel from the winding machine and cure it with resin to form a grid panel blank.

[0011] Take a whole piece of adhesive film and lay it flat on the upper surface of the honeycomb core; during the process of applying grid-shaped glue to the adhesive film, instantaneously heat the complete adhesive film on the end face of the honeycomb core. When the heated adhesive film becomes soft and its viscosity decreases and it sags under the action of gravity, apply hot air axially in the opposite direction of the honeycomb cell holes, so that the sagging adhesive film bulges upward, breaks, and shrinks and aggregates on the end face of the honeycomb core cell wall, forming a grid-shaped adhesive film with a uniform surface morphology; turn the honeycomb core over and perform grid-shaped glue application on the second side of the honeycomb core in the same manner.

[0012] Assemble the upper panel of the grid panel, the lower panel of the grid panel, and the processed honeycomb core into one body. When assembling, it is necessary to ensure that the L-direction fiber tows of the grid panel are aligned with the L-direction of the honeycomb core, and at the same time, the L-direction fiber tows of the upper panel of the grid panel and the lower panel of the grid panel are directly attached to the honeycomb core respectively, forming a stable and symmetrical grid panel sandwich structure board.

[0013] Cure the grid panel sandwich structure board under vacuum conditions by heating and pressurizing to obtain a bending test piece of a grid panel low-density aluminum honeycomb core sandwich structure.

[0014] In the second aspect, a bending test piece of a grid panel low-density aluminum honeycomb core sandwich structure is obtained by the preparation process of a bending test piece of a grid panel low-density aluminum honeycomb core sandwich structure described in the first aspect.

[0015] According to the bending test piece of a grid panel low-density aluminum honeycomb core sandwich structure and the preparation process provided by the present invention, the following beneficial effects are achieved:

[0016] (1) A bending test piece and preparation process of a grid panel low-density aluminum honeycomb core sandwich structure provided by the present invention. The outer dimensions of the bending test piece of the grid panel low-density aluminum honeycomb core sandwich structure are designed as L (1000 mm ± 5 mm) × W (100 mm ± 2 mm). The width of the W-direction dimension can accommodate at least 10 complete honeycomb core cells. At the same time, the W-direction can also accommodate a larger number of L-direction carbon fiber grid filaments, which can effectively reduce the edge effect during the testing process of the grid panel filaments and aluminum honeycomb core in the test piece, and improve the authenticity and reliability of the test data.

[0017] (2) A bending test piece and preparation process of a grid panel low-density aluminum honeycomb core sandwich structure provided by the present invention. The grid panel is directly adhesively bonded to the honeycomb core along the fiber bundles of the L-direction filaments, reducing the influence of the orthotropic properties of the grid panel on the bending performance of the scaled-down part.

[0018] (3) A bending test piece and preparation process of a grid panel low-density aluminum honeycomb core sandwich structure provided by the present invention. A thin and complete adhesive film is laid flat on the end face of the honeycomb core. The complete adhesive film on the end face of the honeycomb core is instantaneously heated to make the adhesive film instantaneously soften and concave. At the same time, hot air is applied axially in the opposite direction along the honeycomb cell holes to assist in heating the adhesive film, causing the adhesive film to bulge, break, shrink and uniformly gather on the side wall end face of the honeycomb core cell, forming a grid-shaped resin adhesive tumor with a uniform surface morphology. Through the above treatment, the actual adhesive consumption of the adhesive film can be effectively increased, the adhesive area between the honeycomb and the grid can be utilized to the greatest extent, the structural load-bearing efficiency can be improved. At the same time, the cumbersome local strengthening and load equalization treatments such as step-by-step pasting of fiberglass cloth before testing the bending test piece of the grid panel sandwich board can be omitted, simplifying the test process and improving the efficiency of the model development and production rhythm. Description of the Drawings

[0019] Figure 1 It is a schematic diagram of the structure of the bending test piece of the grid panel low-density aluminum honeycomb core sandwich structure

[0020] Figure 2 It is the low-density aluminum honeycomb after grid-shaped gluing

[0021] 1 - Grid panel (1-1 Upper panel of the grid panel, 1-2 Lower panel of the grid panel), 2 - Honeycomb core, 3 - Adhesive film (3-A Adhesive film in the initial state, 3-B Grid-shaped adhesive film). Detailed Embodiments

[0022] The present invention will be described in detail below, and the features and advantages of the present invention will become clearer and more definite with these descriptions.

[0023] As used herein, the term "exemplary" means "serving as an example, embodiment, or illustration". Any embodiment described as "exemplary" herein need not be construed as superior or better than other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings need not be drawn to scale unless otherwise specified.

[0024] The present invention provides a preparation process for a bending test piece of a grid panel low-density aluminum honeycomb core sandwich structure. The bending test piece of the grid panel low-density aluminum honeycomb core sandwich structure mainly includes a grid panel (1), a low-density honeycomb core (2), and an adhesive film (3). The preparation process includes the following steps:

[0025] I. Grid panel layup design: Determine the grid spacing parameters a, b and the tow width parameter s of the grid panel according to the design parameters of the full-size solar wing substrate. The grid panel (1) usually includes an upper grid panel surface (1-1) and a lower grid panel surface (1-2), both of which are double-layer orthogonal carbon fiber grid panels (grid spacing is a×b; a≤6mm, b≤6mm). It is formed by winding, shaping, adjusting, and curing a layer of L-direction (length direction) discrete fiber tows (tow spacing is a) and a layer of W-direction (width direction) discrete fiber tows (tow spacing is b). The upper grid panel surface (1-1) and the lower grid panel surface (1-2) are laid up in opposite directions on both sides of the low-density honeycomb core (2) so that the sandwich structure formed by the composite of the two-layer grid panel and the honeycomb core is a stable symmetric sandwich structure.

[0026] The outer dimensions of the bending test piece of the grid panel low-density aluminum honeycomb core sandwich structure are designed as L(1000mm±5mm)×W(100mm±2mm). The W-direction dimension can accommodate at least 10 complete honeycomb core cells. At the same time, the W-direction can also accommodate a larger number of L-direction carbon fiber grid tow numbers (the number of L-direction carbon fiber grid tows is (100±2) / b, b≤6mm), which can effectively reduce the edge effect during the testing process of the grid panel tows and the aluminum honeycomb core in the test piece and improve the authenticity and reliability of the test data.

[0027] The low-density aluminum honeycomb core is selected from the aluminum honeycomb core produced by Hexcel Corporation with the specification of CRIII-3 / 8-5056-.0007P-1.0 or the PAMG-XR1-1.0-3 / 8-0.0007P-5056 produced by Plascore Corporation. This type of aluminum honeycomb core is prepared with an ultra-thin 5056 aluminum foil with a thickness of only 18μm. The cell size (inner diameter of the cell inscribed circle) reaches 9.52mm, and the bulk density is 16kg / m 3 , or domestic low-density series honeycomb cores. The side wall thickness of the honeycomb core is 18-20μm, the cell size (inner diameter of the cell inscribed circle) reaches 9.0-9.8mm, and the bulk density is 16-17.6kg / m 3 .

[0028] II. Grid panel winding and laying: According to the determined grid spacing parameter and tow width parameter, design the winding program parameters of the winding machine. Start the L-direction fiber winding with impregnated or coated carbon fiber, and the tow spacing is a. After the L-direction fiber winding is completed, adjust the winding machine program parameters and start the W-direction fiber winding, and the tow spacing is b.

[0029] III. Grid panel laying adjustment and curing: The wound grid panel is removed from the winding machine and transferred to the platform. Use tools such as tweezers and pressing plates to adjust the fiber displacement and bundled fibers that may occur during the transfer process to the theoretical position, encapsulate, evacuate, and complete the curing of the resin on the fiber according to the corresponding resin curing system to form a grid panel blank.

[0030] IV. Honeycomb core grid sizing: Place the adhesive film (3) on the end face of the honeycomb core (2) on the grid sizing workbench, and perform grid sizing according to the grid sizing process parameters. The adhesive film (3) is generally a complete adhesive film with a thickness of 0.1 mm to 0.2 mm. The adhesive film is Redux320UL or J-312L hot-break adhesive film. When in use, take it out of the cold storage, remove the release paper on both sides of the adhesive film, and present a whole adhesive film material with a smooth, complete and uniform thickness on the (3-A) surface. Then lay it flat on the upper surface of the honeycomb core (2). During the grid sizing process of the adhesive film, instantaneously heat the complete adhesive film on the end face of the honeycomb core. After being heated, the adhesive film becomes soft and its viscosity decreases and it sags under the action of gravity. At this time, apply hot air axially in the opposite direction along the honeycomb cell holes (the temperature of the hot air is 82 - 88 °C). At this time, the sagging adhesive film bulges upward again, breaks and shrinks and gathers at the end face of the honeycomb cell wall, forming a grid adhesive film (3-B) with a uniform surface morphology. At this time, the grid sizing is completed, and the state of the honeycomb core after completion is as Figure 2 shown. After the grid sizing of one side of the single-sided honeycomb core is completed, turn over the honeycomb core and its clamping workpiece, and perform the grid sizing of the second side of the honeycomb core.

[0031] Since the end face area of the aluminum honeycomb core is much smaller than the area of the grid panel, perform grid sizing treatment on the end face of the honeycomb core. Lay a complete adhesive film with a relatively thin thickness flat on the end face of the honeycomb core, instantaneously heat the complete adhesive film on the end face of the honeycomb core to make the adhesive film instantaneously soften and sag, and at the same time apply hot air axially in the opposite direction along the honeycomb cell holes to assist in heating the adhesive film, so that the adhesive film bulges, breaks, shrinks and uniformly gathers at the end face of the honeycomb cell side wall, forming a grid resin adhesive tumor with a uniform surface morphology. Through the above treatment, the actual adhesive consumption of the adhesive film can be effectively increased, the adhesive area between the honeycomb and the grid can be utilized to the greatest extent, the structural load-bearing efficiency can be improved, and at the same time, the local strengthening and load equalization treatments such as the stepped surface-mounted fiberglass cloth before the bending test piece of the grid panel sandwich plate can be omitted, the test process can be simplified, and the production rhythm efficiency of the model development can be improved.

[0032] V. Composite Assembly of Bending Test Specimen: Assemble the upper panel (1-1) of the grid panel and the lower panel (1-2) of the grid panel, which are processed in Step III, and the honeycomb core (2) processed in Step IV into one body. During assembly, it is necessary to ensure that the L-direction fiber bundles of the grid panel are aligned with the L-direction of the honeycomb core. At the same time, the L-direction fiber bundles of the upper panel of the grid panel and the lower panel of the grid panel are directly bonded to the honeycomb core respectively, forming a stable and symmetric grid panel sandwich structure board.

[0033] The single-layer grid panel is an orthogonal grid panel. Generally, to improve the stiffness and load-bearing performance of the grid panel honeycomb core sandwich panel, the filaments (L-direction fiber bundles) are usually located on the outer side of the panel (i.e., the side far from the honeycomb core). Considering that the carbon fiber grid panel of the present invention is a discontinuous and orthogonal grid panel, which is formed by bonding and curing a layer of transverse discrete fiber bundles and a layer of longitudinal discrete fiber bundles, the force transmission path from the panel to the aluminum honeycomb core is relatively complex. Therefore, the fiber bundles of the grid panel along the 1000±5 mm direction (L-direction fiber bundles) are directly bonded to the honeycomb core, reducing the influence of the orthotropic properties of the grid panel on the bending performance of the scaled specimen. Compared with directly bonding the W-direction fiber bundles to the honeycomb core, directly contacting the L-direction with the honeycomb core can transfer the bending stress of the high-performance, low-density and weak-stiffness honeycomb core along the L-direction of the honeycomb core to the grid panel. The force transmission path is direct and efficient, the grid panel shares the load more evenly, and the structural consistency is good.

[0034] VI. Curing Treatment of Bending Test Specimen: Vacuum bag package the grid panel sandwich structure board processed in Step V, evacuate the air, heat and pressurize for curing. After curing, wait for the vacuum bag system to return to room temperature and then demold, trim and machine process, that is, complete the preparation of the bending test specimen of the grid panel low-density aluminum honeycomb core sandwich structure.

[0035] The preparation process of the bending test specimen of the grid panel low-density aluminum honeycomb core sandwich structure of the present invention solves the problems existing in the development process of the bending test specimen of the grid panel sandwich structure of the existing solar wing substrate, such as poor consistency of the failure parts in the test results and large data fluctuations. It omits the cumbersome local strengthening and load sharing treatment such as pasting fiberglass cloth on the step table before testing, simplifies the test process, improves the production efficiency of the model development. The bending test specimens prepared by using the preparation process of the bending test specimen of the grid panel low-density aluminum honeycomb core sandwich structure have uniform and stable bending test failure parts, small test data dispersion, and the test results meet the requirements of design and use indicators.

[0036] Example

[0037] Example 1

[0038] Preparation process of a bending test piece of a grid panel low-density aluminum honeycomb core sandwich structure. The bending test piece of the grid panel low-density aluminum honeycomb core sandwich structure mainly includes a grid panel (1), a low-density honeycomb core (2) and an adhesive film (3). The preparation process includes the following steps:

[0039] I. Grid panel layup design: Determine the outer dimensions of the bending test piece of the grid panel low-density aluminum honeycomb core sandwich structure, the grid spacing parameters a, b of the grid panel and the tow width parameter s according to the design parameters of the full-size solar wing substrate. Among them, the grid spacing of the upper panel (1-1) and the lower panel (1-2) of the grid panel is a×b, a = 6mm, b = 4mm. a is the fiber tow spacing in the L direction, and b is the fiber tow spacing in the W direction.

[0040] The outer dimensions of the bending test piece of the grid panel low-density aluminum honeycomb core sandwich structure are designed as L (1000mm)×W (100mm). The tow width parameter s is 2mm.

[0041] The low-density aluminum honeycomb core is an aluminum honeycomb core of the specification CRIII-3 / 8-5056-.0007P-1.0 produced by Hexcel Corporation. This aluminum honeycomb core is prepared with an ultra-thin 5056 aluminum foil with a thickness of only 18μm. The cell size (inner diameter of the cell inscribed circle) reaches 9.52mm, the height is 24mm, and the bulk density is 16kg / m 3 .

[0042] II. Grid panel winding and layup: Design the winding machine winding program parameters according to the determined grid spacing parameters, and successively wind the carbon fibers impregnated or coated with epoxy resin in the L direction and the W direction.

[0043] III. Grid panel layup adjustment and curing: The wound grid panel is taken off the winding machine and transferred to a platform. Use tools such as tweezers and pressing plates to adjust the fibers that may cause fiber displacement and bunching during the transfer process to the theoretical position, encapsulate, evacuate, and complete the curing of the resin on the fibers at a temperature of 165±2°C and a pressure of 0.1MPa to form a grid panel blank.

[0044] IV. Honeycomb core grid sizing: Place the honeycomb core (2) with the sizing film (3) laid on its end face on the grid sizing workbench, and perform grid sizing according to the grid sizing process parameters. The sizing film (3) is a complete sizing film with a thickness of 0.1 mm to 0.2 mm (material Redux320UL). When in use, take it out of the cold storage, remove the release papers on both sides of the sizing film, presenting a whole sizing film material with a smooth, complete and uniform thickness on the (3-A) surface. Then lay it flat on the upper surface of the honeycomb core (2). During the grid sizing of the sizing film, instantaneously heat the complete sizing film on the end face of the honeycomb core. After heating, the sizing film becomes soft and its viscosity decreases, and it sags under the action of gravity. At this time, apply hot air at 82 - 88 °C along the axial direction of the honeycomb cell holes in the reverse direction, so that the sagging sizing film bulges upward, breaks and shrinks and accumulates at the end face of the honeycomb core cell wall, forming a grid sizing film (3-B) with a uniform surface morphology. The state of the honeycomb core after completion is as Figure 2 shown. After completing the grid sizing of one side of the single-sided honeycomb core, turn over the honeycomb core and its clamping workpiece, and perform the grid sizing of the second side of the honeycomb core.

[0045] V. Composite assembly of bending test pieces: Assemble the upper panel (1-1) of the grid panel, the lower panel (1-2) of the grid panel processed in Step III and the honeycomb core (2) processed in Step IV into one body. During assembly, ensure that the L-direction fiber bundles of the grid panel are aligned with the L-direction of the honeycomb core. At the same time, the L-direction fiber bundles of the upper panel of the grid panel and the lower panel of the grid panel are directly attached to the honeycomb core respectively, forming a stable and symmetric grid panel sandwich structure board.

[0046] VI. Curing treatment of bending test pieces: Vacuum bag package the grid panel sandwich structure board processed in Step V, evacuate, heat and pressurize for curing. After curing is completed, wait for the vacuum bag system to return to room temperature, then perform demolding, trimming and machining, that is, complete the preparation of the grid panel low-density aluminum honeycomb core sandwich structure bending test piece.

[0047] When testing the three-point bending stiffness and four-point bending strength of the test piece, all (100%) of the test failure parts occur inside the loading area, that is, all are effective failure damages, and the test load dispersion coefficient is about 1.2%.

[0048] Comparative Example

[0049] Comparative Example 1

[0050] This Comparative Example 1 is the same as Example 1, except that the upper panel (1-1) of the grid panel, the lower panel (1-2) of the grid panel processed and the honeycomb core (2) processed are assembled into one body. During assembly, the W-direction fiber bundles of the upper panel of the grid panel and the lower panel of the grid panel are directly attached to the honeycomb core respectively, forming a symmetric grid panel sandwich structure board.

[0051] During the three-point bending stiffness and four-point bending strength tests of the test piece, the failure site is likely to occur at the loading point, that is, it is prone to abnormal premature failure due to stress concentration, and the proportion of abnormal failure is about 25%. The discrete coefficient of the test load is about 11.6%.

[0052] Comparative Example 2

[0053] This Comparative Example 2 is the same as Example 1, except that the external dimension of the bending test piece of the grid panel low-density aluminum honeycomb core sandwich structure is designed as L600mm × W55mm.

[0054] During the three-point bending stiffness and four-point bending strength tests of the test piece, the proportion of the abnormal failure site is about 40%, and the discrete coefficient of the test load is about 18.6%. Using the surface-mounted fiberglass cloth test method, the proportion of the abnormal failure site is about 5%, and the discrete coefficient of the test load is about 4.3%.

[0055] Comparative Example 3

[0056] This Comparative Example 3 is the same as Example 1, except that during the grid sizing, the traditional sizing process is manual sizing, which requires frequent melting, brushing, and drying of the adhesive film, increasing the volatile content and not achieving the weight reduction effect.

[0057] The present invention has been described in detail above in combination with specific embodiments and exemplary examples, but these descriptions should not be construed as limiting the present invention. Those skilled in the art understand that without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications, or improvements can be made to the technical solutions and their implementation manners of the present invention, and these all fall within the scope of the present invention. The protection scope of the present invention is subject to the appended claims.

[0058] The content not described in detail in the specification of the present invention belongs to the well-known technology of those skilled in the art.

Claims

1. A preparation process for a bending test piece of a grid panel low-density aluminum honeycomb core sandwich structure, characterized in that, It includes the following steps: Determine the external dimension, grid spacing parameter and tow width parameter of the grid panel aluminum honeycomb core sandwich structure bending test piece according to the design parameters of the full-size solar wing substrate; the external dimension of the grid panel aluminum honeycomb core sandwich structure bending test piece is designed to be 1000mm ± 5mm in the L direction and 100mm ± 2mm in the W direction; the L-direction fiber tow spacing a of the grid panel ≤ 6mm, and the W-direction fiber tow spacing b ≤ 6mm; According to the determined grid spacing parameter and tow width parameter, perform orthogonal winding on the winding machine with fiber impregnated or coated with resin; remove the wound grid panel from the winding machine and cure it with resin to form a grid panel blank; Take a whole piece of adhesive film and lay it flat on the upper surface of the honeycomb core; during the grid sizing process of the adhesive film, instantaneously heat the complete adhesive film on the end face of the honeycomb core. When the heated adhesive film becomes soft and its viscosity decreases and it sags under the action of gravity, apply hot air in the reverse direction along the axial direction of the honeycomb cells, so that the sagging adhesive film bulges upward, breaks and shrinks and aggregates on the end face of the honeycomb cell wall to form a grid-shaped adhesive film with a uniform surface morphology; turn the honeycomb core over and perform grid sizing on the second side of the honeycomb core in the same manner; Assemble the upper panel of the grid panel, the lower panel of the grid panel and the processed honeycomb core into one body. During assembly, ensure that the L-direction fiber tows of the grid panel are aligned with the L direction of the honeycomb core, and at the same time, the L-direction fiber tows of the upper panel of the grid panel and the lower panel of the grid panel are directly attached to the honeycomb core respectively to form a stable and symmetrical grid panel sandwich structure plate; Cure the grid panel sandwich structure plate under vacuum conditions by heating and pressing to obtain a grid panel aluminum honeycomb core sandwich structure bending test piece.

2. The preparation process of the bending test piece of the grid panel low-density aluminum honeycomb core sandwich structure according to claim 1, characterized in that, The grid panel includes an upper panel of the grid panel and a lower panel of the grid panel, both of which are double-layer orthogonal carbon fiber grid panels, and the grid spacing is consistent with the grid parameters of the solar wing substrate product.

3. The preparation process of the bending test piece of the grid panel low-density aluminum honeycomb core sandwich structure according to claim 1, characterized in that, In the step of performing orthogonal winding on the winding machine with fiber impregnated or coated with resin according to the determined grid spacing parameter, first start the L-direction fiber winding with impregnated or coated carbon fiber. After the L-direction fiber winding is completed, adjust the program parameters of the winding machine and then perform the W-direction fiber winding.

4. The preparation process of the bending test piece of the grid panel low-density aluminum honeycomb core sandwich structure according to claim 1, characterized in that, After the step of removing the wound grid panel from the winding machine, it also includes the adjustment of fiber laying, and adjusting the fiber displacement and bundled fibers caused during the transfer process to the theoretical position.

5. The preparation process of the bending test piece of the grid panel low-density aluminum honeycomb core sandwich structure according to claim 1, characterized in that, In the step of taking a whole piece of adhesive film with a smooth, complete and uniform thickness and then laying it flat on the upper surface of the honeycomb core, the adhesive film is a complete adhesive film with a thickness of 0.1mm - 0.2mm.

6. The preparation process of the bending test piece of the grid panel low-density aluminum honeycomb core sandwich structure according to claim 1, characterized in that, In the step of taking a whole piece of film material with a smooth, complete and uniform thickness, and then laying it flat on the upper surface of the honeycomb core, the side wall thickness of the honeycomb core is 18 - 20 μm, the inscribed circle diameter of the core cell is 9.0 - 9.8 mm, and the bulk density is 16 - 17.6 kg / m 3 .

7. The preparation process of the bending test piece of the grid panel low-density aluminum honeycomb core sandwich structure according to claim 1, characterized in that, In the step of applying hot air in the reverse direction along the axial direction of the honeycomb cells, the temperature of the hot air is 82 - 88°C.

8. A bending test piece of a grid panel low-density aluminum honeycomb core sandwich structure, characterized in that, It is obtained by the preparation process of a grid panel low-density aluminum honeycomb core sandwich structure bending test piece according to one of claims 1 to 7.

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