Five-way honeycomb sandwich lightweight structure composite material and preparation method thereof

Abstract

The invention discloses a five-way honeycomb sandwich lightweight structure composite material and a preparation method thereof, and belongs to the technical field of composite materials. The invention provides a co-curing forming process adopting a multidirectional honeycomb sandwich structure aiming at the technical problems that a traditional layering method depends on manual operation, the repetitive workload is large, and the structural design is difficult to consider mechanical properties and light weight at the same time. The preparation method comprises the steps of honeycomb unit design, honeycomb laying layer structure design, glue injection filling, curing forming and the like, and the requirements of light weight and automatic production can be met while the high strength of the composite material is achieved.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology, specifically a five-dimensional honeycomb sandwich lightweight structural composite material and its preparation method. Background Technology

[0002] Currently, with increasingly stringent requirements for product weight and structural strength, the selection of fiber resins for composite materials is becoming more stringent. To explore new avenues for composite material layup methods, honeycomb reinforced sandwich structures have been introduced as internal fillers for the substrate. This fully utilizes the inherent mechanical properties of honeycomb to conduct research on multi-directional layup structures. While traditional honeycomb materials exhibit excellent performance in a uniaxial direction, they often fall short under complex stress environments. In the packaging industry, transportation, lifting, and stacking processes place strict demands on the load-bearing capacity of the packaging substrate, and the weight of the packaging product itself must strictly adhere to design specifications. Traditional weight reduction measures for packaging boxes involve optimizing the dimensions of metal structural components and reducing the number of coats of primer, sealant, and topcoat. However, this results in complex structural designs and high processing costs, and the reduced material can pose certain risks to the sealing performance of the packaging box. Therefore, introducing multi-directional honeycomb sandwich structures can supplement the strength of key load-bearing components in the packaging box. The intelligent design of the honeycomb core structure achieves the lightweight requirements of the packaging product, improves product maintainability, and, by rationally allocating the size of the honeycomb cells instead of the skin thickness, shortens the product molding time and reduces production costs, which is of great significance. Summary of the Invention

[0003] The purpose of this invention is to solve the technical problems existing in the preparation of composite materials, such as the reliance on manual operation, large amount of repetitive work, and difficulty in balancing mechanical properties and lightweighting in structural design. This invention provides a five-directional honeycomb sandwich lightweight structural composite material and its preparation method. It adopts low-cost co-curing molding of multi-directional honeycomb sandwich structure, which has both reasonable structural design and process feasibility. It can meet the requirements of lightweighting and automated production while achieving high strength performance of composite materials.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing a five-dimensional honeycomb sandwich lightweight structural composite material includes the following steps:

[0006] 1) Cellular cell design: Based on the length, width and thickness of the product's load-bearing area, the direction of force and the maximum load-bearing requirements, design the cell size and stacking direction of the cellular structure. The cellular cell includes XY-direction cellular cells and Z-direction cellular cells. The XY-direction cellular cells are arranged in a sheet-like manner, and the Z-direction cellular cells are perpendicular to the XY-direction cellular cells and are in the thickness direction of the cellular cells.

[0007] 2) Cellular layup structure design: Cellular cells in the XY and Z directions are laid out in five directions to form a multi-directional layup structure;

[0008] 3) Honeycomb layup: Honeycomb unit layers in the same direction are laid in a staggered stacking manner, and the gaps between honeycomb unit layers in different directions are filled with a mixture of chopped fibers and resin, and prefabricated unidirectional fiber bundles are filled at the bottom of the honeycomb unit gaps.

[0009] 4) Adhesive injection and filling: A space for adhesive injection is reserved on the upper surface of each honeycomb unit. Adhesive is injected into the gaps of the honeycomb unit using gravity injection to fill the upper gap area. After the layers are laid, adhesive is injected into the reserved area and the adhesive is vibrated by a vibration device to ensure that the adhesive is fully filled into the honeycomb unit and the gaps between layers.

[0010] 5) Curing and molding: The structure after glue injection is cured. The glue injection time is set to be longer than the initial curing time of the glue. Finally, the structure is placed in an oven for heating and curing to obtain a honeycomb sandwich composite structure.

[0011] Furthermore, the XY-direction cellular cell layers of the cellular unit have a hexagonal structure.

[0012] Furthermore, the thickness dimension of the cellular cell in the Z direction is 1mm or 2mm.

[0013] Furthermore, reinforcing ribs are added to the Z-axis honeycomb units to improve the Z-axis support strength.

[0014] Furthermore, when the surface of the cellular unit layer does not meet the requirements for flatness, short-cut fibers are used to fill the irregular areas on the surface of the unit layer.

[0015] Furthermore, during the cell cell installation process, self-spraying adhesive or coating with viscous resin is applied between the cell layers to enhance interlayer adhesion.

[0016] Furthermore, the adhesive is a mixture of resin and chopped fibers, and the viscosity of the adhesive is adjusted according to the complexity of the honeycomb structure to ensure uniformity and flowability of the adhesive.

[0017] Furthermore, the unidirectional fiber bundle is a fiber bundle pre-impregnated with resin.

[0018] Furthermore, the five directions include 0 degrees, 45 degrees, 90 degrees, -45 degrees and the Z direction, to achieve quasi-isotropic structural characteristics.

[0019] Furthermore, the structure after resin injection is cured using resin transfer molding (RTM) or vacuum-assisted resin infusion (VARI) processes.

[0020] A five-dimensional honeycomb sandwich lightweight structural composite material is obtained by the above preparation method.

[0021] The beneficial effects achieved by this invention are as follows:

[0022] 1. This invention provides a rapid prototyping method for honeycomb sandwich composite materials suitable for multi-directional lay-up. By adopting a prefabricated honeycomb unit structure and gap filling design, it is possible to quickly fill the thickness or achieve structural forming in large-size and thick structures, effectively improving molding efficiency, simplifying interlayer operation processes, and reducing labor costs.

[0023] 2. The prefabricated honeycomb structure used in this invention has good conformability. Combined with chopped fibers and resin filling, it can achieve local reinforcement and bonding of complex curved areas, avoid gaps caused by insufficient flatness, and improve bonding and molding quality.

[0024] 3. This invention fills the gaps between the layers of the honeycomb unit with prefabricated unidirectional fiber bundles and uses automatic glue injection and vibration-assisted filling technology to make the glue evenly distributed in the upper half of the honeycomb and the interlayer gaps, effectively avoiding problems such as insufficient glue, bridging, dry spots and buckling, and improving the internal density and structural stability.

[0025] 4. The honeycomb layup structure used in this invention includes five directions: 0° / ±45° / 90° / Z-direction, forming a quasi-isotropic sandwich structure, which significantly improves the comprehensive mechanical properties of the composite material in the directions of tension, compression, bending and interlaminar shear.

[0026] 5. Compared with the traditional manual prepreg paste preparation method, the present invention has a higher level of automation integration, the glue injection process has more operational freedom, which is conducive to the formation of stable and reliable composite structures and is suitable for industrial application scenarios with high requirements for batch production and consistency.

[0027] 6. The present invention has a significant lightweight effect on the overall structure and features flexible structural design, easy processing and molding, and strong adaptability. It is suitable for various application fields with lightweight and high strength requirements, such as aerospace, transportation, and special equipment. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a cellular XY unidirectional layer according to an embodiment of the present invention.

[0029] Figure 2 This is a schematic diagram of a cellular Z-axis unidirectional layer according to an embodiment of the present invention.

[0030] Figure 3 This is a schematic diagram of a prefabricated unidirectional fiber in a cellular unidirectional layer according to an embodiment of the present invention.

[0031] Figure 4 This is a schematic diagram of the XYZ direction layup in an embodiment of the present invention.

[0032] Figure 5This is a schematic diagram of the glue injection area of ​​the unit layer in an embodiment of the present invention.

[0033] Figure 6 This is a three-dimensional schematic diagram of the adhesive injection after the honeycomb layer is laid according to an embodiment of the present invention.

[0034] Figure 7 This is a two-dimensional schematic diagram of the glue injection process according to an embodiment of the present invention. Detailed Implementation

[0035] To make the various technical features, advantages, or effects of the present invention more apparent and understandable, detailed descriptions are provided below through embodiments and accompanying drawings.

[0036] like Figures 1 to 7 As shown in the figure, this invention discloses a method for preparing a five-dimensional honeycomb sandwich lightweight structural composite material, including the following steps:

[0037] Step 1: Cellular cell design and prefabrication

[0038] Based on the dimensions (length, width, and thickness) of the load-bearing area of ​​the target product, as well as the requirements for the direction of force and maximum load-bearing capacity, determine the unit size and laying direction of the honeycomb structure. Figure 1 The XY direction cellular cell layer is shown. Figure 2 The Z-direction cellular cell layer is shown, which together form mechanical support in different directions.

[0039] When the surface of the load-bearing area is not smooth and cannot meet the requirement of tight bonding of the honeycomb layer, it can be done as follows: Figure 3 As shown, chopped fibers are used to fill irregular areas on uneven surfaces, and unidirectional fiber bundles are prefabricated to fill the gaps between honeycomb cell layers, improving fit and structural integrity. The cell size d in the thickness direction of the honeycomb cell is typically 1mm or 2mm. Honeycomb cells in the same direction are preferably staggered to reduce the gaps between adjacent cells, while honeycomb cell layers in different directions are staggered and stacked. A mixture of fiber, resin, and chopped fiber is filled into the gaps between the cells to form a filling structure.

[0040] Step 2: Honeycomb Layer Structure Design

[0041] The layup sequence and orientation combination are designed based on the overall thickness of the product, with a five-directional layup structure preferred, including 0-degree, ±45-degree, 90-degree, and Z-directional honeycomb unit layers, forming a structure such as... Figure 4 The XYZ three-dimensional layup structure is shown.

[0042] Step 3: Honeycomb Layer Layup

[0043] When the XY-axis honeycomb layers are stacked in the same direction, it is preferable to lay them with a staggered distance of one honeycomb cell to reduce the impact concentration in the Z-axis. When using anisotropic stacking, unidirectional fiber bundles need to be pre-placed in the honeycomb gaps to enhance their Z-axis support performance, and filled with a mixture of chopped fibers and resin to prevent the honeycomb structure from deforming or slipping during the pressing process.

[0044] like Figure 5 As shown, a glue-filling area is reserved in the upper half of the cellular unit, and interlayer adhesion is enhanced by spraying adhesive resin or 3M self-spraying adhesive.

[0045] Step 4: Design and filling of the glue injection method

[0046] like Figure 6 and Figure 7 As shown, the adhesive injection channels are set according to the layup structure. For unidirectional honeycomb cell layers, the adhesive can be directly injected into the reserved gaps inside the honeycomb cells. For anisotropic honeycomb structures, the lower trapezoidal space needs to be filled with unidirectional fiber bundles beforehand, and then the upper area is filled with the adhesive by its own gravity.

[0047] In the final resin injection stage, a vibration device is used to vibrate the structure to ensure that the resin can fully flow into the honeycomb interior and all residual voids between layers, thus ensuring the density and integrity of the composite structure.

[0048] The injection material (adhesive liquid) is formed by mixing short-cut fibers, matrix resin, etc. in a certain proportion. Its viscosity and flowability need to be controlled according to the actual injection path and the complexity of the honeycomb structure to ensure that the injection process is completed smoothly.

[0049] Step 5: Curing and Shaping

[0050] Depending on the thickness of the honeycomb structure layers and the injection method, either RTM (Resin Transfer Molding) or VARI (Vacuum Assisted Resin Infusion) processes are selected for curing. The injection time should be longer than the initial curing time to ensure that the adhesive is fully filled into the structure. After the layers are laid up, the entire structure is placed in an oven for heating and curing to accelerate the adhesive reaction and form a complete composite material.

[0051] Implementation results:

[0052] The five-dimensional honeycomb sandwich composite structure prepared in this embodiment has the following advantages:

[0053] (1) The near-equal strength properties in all directions are achieved through a multi-directional honeycomb laminate structure of 0° / ±45° / 90° / Z direction, which significantly improves the tensile, compressive, bending and interlaminar shear properties of the composite material.

[0054] (2) The honeycomb unit structure has good conformability and can be adapted to load-bearing areas with complex geometric shapes;

[0055] (3) The filling design of prepreg unidirectional fiber and chopped filler can optimize the flow of adhesive during the molding process and ensure that the overall structure is densely formed;

[0056] (4) The entire layup and injection process is simple and can be done manually, making it suitable for integrated lightweight manufacturing of diverse structural components.

[0057] The parts of this invention not described in detail are techniques known to those skilled in the art.

[0058] The specific embodiments of the present invention disclosed above are intended to help understand the content of the present invention and to implement it accordingly. Those skilled in the art will understand that various substitutions, changes, and modifications are possible without departing from the spirit and scope of the present invention. The present invention should not be limited to the content disclosed in the embodiments of this specification; the scope of protection of the present invention is defined by the claims.

Claims

1. A method for preparing a five-dimensional honeycomb sandwich lightweight structural composite material, characterized in that, Includes the following steps: 1) Cellular cell design: Based on the length, width and thickness of the product's load-bearing area, the direction of force and the maximum load-bearing requirements, design the cell size and stacking direction of the cellular structure. The cellular cell includes XY-direction cellular cells and Z-direction cellular cells. The XY-direction cellular cells are arranged in a sheet-like manner, and the Z-direction cellular cells are perpendicular to the XY-direction cellular cells and are in the thickness direction of the cellular cells. 2) Cellular layup structure design: Cellular cells in the XY and Z directions are laid out in five directions to form a multi-directional layup structure; 3) Honeycomb layup: Honeycomb unit layers in the same direction are laid in a staggered stacking manner, and the gaps between honeycomb unit layers in different directions are filled with a mixture of chopped fibers and resin, and prefabricated unidirectional fiber bundles are filled at the bottom of the honeycomb unit gaps. 4) Adhesive injection and filling: A space for adhesive injection is reserved on the upper surface of each honeycomb unit. Adhesive is injected into the gaps of the honeycomb unit using gravity injection to fill the upper gap area. After the layers are laid, adhesive is injected into the reserved area and the adhesive is vibrated by a vibration device to ensure that the adhesive is fully filled into the honeycomb unit and the gaps between layers. 5) Curing and molding: The structure after glue injection is cured. The glue injection time is set to be longer than the initial curing time of the glue. Finally, the structure is placed in an oven for heating and curing to obtain a honeycomb sandwich composite structure.

2. The preparation method according to claim 1, characterized in that, The XY-axis cellular cell layer has a hexagonal structure.

3. The preparation method according to claim 1, characterized in that, The thickness of the cellular cell in the Z direction is 1mm or 2mm, and a reinforcing rib structure is introduced into the cellular cell in the Z direction.

4. The preparation method according to claim 1, characterized in that, When the surface of the cell unit layer does not meet the flatness requirements for laying, short-cut fibers are used to fill the irregular areas on the surface of the unit layer.

5. The preparation method according to claim 1, characterized in that, During the cell cell installation process, self-spraying adhesive or coating with viscous resin is applied between the cell layers to enhance interlayer adhesion.

6. The preparation method according to claim 1, characterized in that, The adhesive is a mixture of resin and chopped fibers, and its viscosity is adjusted according to the complexity of the honeycomb structure.

7. The preparation method according to claim 1, characterized in that, Unidirectional fiber bundles are fiber bundles pre-impregnated with resin.

8. The preparation method according to claim 1, characterized in that, The five directions include 0 degrees, 45 degrees, 90 degrees, -45 degrees, and the Z direction.

9. The preparation method according to claim 1, characterized in that, The structure after resin injection is cured using resin transfer molding or vacuum-assisted resin infusion processes.

10. A five-dimensional honeycomb sandwich lightweight structural composite material, characterized in that, Obtained by the preparation method according to any one of claims 1-9.

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