A fiber-metal hybrid laminate of a reverse honeycomb sandwich structure and a method of manufacturing

Abstract

A kind of fiber-metal hybrid laminates of reverse honeycomb sandwich structure and preparation method, it is the advanced material supply technology obtained by multidimensional optimization combination of material structure design, lightweight alloy precision machining technology, surface engineering technology, heterogeneous composite material preparation technology.First, using subtractive machining technology, according to the design trajectory, cut the polygonal structure of inner recess, upper and lower layer plate is closed, and the reverse honeycomb sandwich structure of inner recess is formed;Then, the processing surface of metal layer plate is chemically treated, and it is passivated, the purpose is to increase the bonding force between fiber layer and metal layer;Then, fill the viscous mixture in the inner recess structure of metal layer, ensure the multifunctional characteristics and impact resistance of composite laminates;Then, the fiber prepreg is laid between the upper and lower metal plates to obtain the prefabricated fiber-metal hybrid laminates;Finally, the prefabricated hybrid laminates are treated by vacuum bag-hot press tank system for hot pressing and curing to obtain the applicable composite laminates.

Description

Technical Field

[0001] The present invention belongs to the technical field of design and preparation of high-performance composite materials, and in particular relates to a design and preparation method of a lightweight fiber-reinforced metal hybrid laminate composite material with multifunctional structural characteristics. Background Art

[0002] With the development of modern society, the extensive use of aircraft with greater maneuverability and superior stealth has become the magic weapon for success in the aerospace field. This requires aircraft to be lighter and have more diversified functions. Among them, lightweight and multifunctional materials and material structure technologies are the key to achieving the above goals.

[0003] In terms of lightweight material research progress, fiber metal laminates (FMLs), a hybrid material structural system composed of alternating layers of resin-based fiber-reinforced composites and thin metal plates, are a new, efficient, and low-cost composite structural material that combines the dual advantages of metals and advanced composites. Compared with aluminum alloys, they have better damage tolerance (especially impact and fatigue), better corrosion resistance, better fire resistance, and lower density. Compared with composite materials, they have better impact resistance, better electrical conductivity, recyclability, and strong designability. They are very promising alternative materials for the new generation of aircraft structural components and have huge application potential in the aerospace industry. Glass fiber reinforced aluminum alloy laminates (GLARE) have higher manufacturing costs and complexity than aluminum alloy sheets, but compared to metal structures, they have lower areal density, longer service life, and are easier to inspect and maintain during service. Compared to equivalent aluminum alloy components, fiber metal laminate components are over 25% lighter, while costing only about one-third of equivalent fiber reinforced composite components. They are widely used in aircraft fuselage skins, leading edges of vertical and horizontal tail fins, and other areas, significantly improving aircraft endurance and maneuverability. This makes GLARE laminates the most mature and widely used FMLs. Traditional lightweight composite structures are mostly foam and honeycomb sandwich structures. Sandwich structures are lightweight, multifunctional structures primarily consisting of upper and lower panels and a central interlayer. Sandwich structures demonstrate superior performance in weight reduction, energy absorption, cost reduction, and production time reduction. Compared to traditional single-layer panels, sandwich structures with a sandwich core layer and two upper and lower facesheets offer a lighter overall structure due to their higher porosity. The high porosity and low relative density of sandwich structures provide superior mechanical properties, making them an excellent choice for lightweight design. However, the enclosed interior of these cores makes it difficult to achieve multifunctional requirements such as pre-embedding and heat transfer, limiting their widespread adoption.

[0004] Therefore, the use of innovative preparation technology, combining the honeycomb sandwich structure design method with glass fiber reinforced aluminum alloy laminates, and developing new glass fiber reinforced aluminum alloy laminates with sandwich structures will further reduce the weight of the GLARE laminates. At the same time, the use of internal filling solutions in the sandwich will achieve the integration of multiple functions (such as load-bearing and thermal control, stealth, energy absorption, actuation, energy storage, and damping), while compensating for the weakening of strength and stiffness caused by the weight reduction of the material, achieving the ultimate goal of lightweight, miniaturization, diversification, and structural function integration, thereby expanding the scope of application in many fields such as aerospace, national defense, and enhancing the service capability of aircraft. Summary of the Invention

[0005] In order to solve the above problems, the purpose of the present invention is to provide a fiber-metal hybrid laminate with an inverse honeycomb sandwich structure and a preparation method, which covers material structure design, precision processing technology, surface engineering, and heat treatment technology, and can realize the integrated design and manufacturing of lightweight, multifunctional fiber-reinforced metal laminates.

[0006] In order to achieve the above-mentioned object, the present invention provides a fiber-metal hybrid laminate with an inverse honeycomb sandwich structure and a preparation method thereof, comprising the following steps in order:

[0007] 1) First, the multi-layer aluminum alloy sheet is arranged and arranged by aligning its edges. A hexagonal machining track is then carved at the same location on the inner surface of the multi-layer aluminum alloy sheet. Using subtractive machining, the machining tool moves along the machining track while performing a certain amount of cutting along the thickness of the sheet to form a concave hexagonal structure. Based on the requirements of the sheet's operating conditions, the processing areas are mostly clustered and distributed. The subtractive area is connected to the unsubtracted area, that is, the unprocessed material forms the support portion, which, combined with the concave hexagonal structure, forms a concave reverse honeycomb sandwich structure. The thickness-wise cutting amount is calculated based on the strength and impact resistance requirements of the sheet after cutting.

[0008] 2) The inner surface of the machined aluminum alloy sheet is chemically treated. Acetone is used to remove oil from the machined metal surface, followed by phosphoric acid anodizing. This treatment sequentially includes alkaline washing, acid washing, and phosphoric acid anodizing. The phosphoric acid anodizing treatment creates an uneven surface texture on the aluminum alloy surface, increasing surface roughness. This effectively increases the contact area between the aluminum alloy sheet and the fiber prepreg, thereby improving the mechanical locking force between the aluminum alloy sheet and the resin.

[0009] 3) Mixing a high-temperature expansion agent with a multi-physical property filler, adding epoxy resin to form a viscous mixture, and filling it into the concave hexagonal structure of the aluminum alloy plate obtained in step 2). The purpose of adding the high-temperature expansion agent is to allow the expansion agent to expand and flow during the heat curing treatment of the fiber-metal hybrid laminate, fully filling the concave hexagonal structure of the upper and lower laminates, forming a foam-like shock-absorbing effect. The purpose of adding the physical property filler is to increase the functional diversity of the fiber-metal hybrid laminate, and the purpose of adding the epoxy resin is to mix the high-temperature expansion agent and the physical property filler well together to form a viscous mixture that is easy to fill and fix in the concave hexagonal structure of the aluminum alloy laminate.

[0010] 4) Based on actual operating conditions, design and formulate a fiber-metal hybrid laminate structure and fiber prepreg layup method. Utilize manual placement to bond and combine the fiber and metal layers to create a prefabricated fiber-metal hybrid laminate. The fiber-metal hybrid laminate structure can be constructed in 1 / 2, 2 / 3, 3 / 4, or 5 / 6 configurations. The fiber prepreg layup can be unidirectional (0° / 0°), cross-ply (0° / 90°), or cross-ply (+45° / -45°).

[0011] 5) The prefabricated fiber-metal hybrid laminate obtained in step 4) is fabricated into a vacuum bag system and then placed in an autoclave. By setting appropriate temperature T and pressure P, the fiber prepreg solidifies and firmly bonds to the aluminum alloy laminate, forming a dense fiber-metal hybrid laminate. At temperature T, the expansion agent expands upon heating, filling the concave inverse honeycomb structure within the aluminum alloy laminate, forming a honeycomb sandwich structure that reduces weight and absorbs energy.

[0012] The present invention provides a fiber-metal hybrid laminate with an inverse honeycomb sandwich structure and a preparation method thereof. This is an advanced material supply technology, based on the principle of providing lightweight, multifunctional materials for aerospace vehicles, resulting from a multi-dimensional optimization combination of material structure design, lightweight alloy precision machining technology, surface engineering technology, and heterogeneous composite material preparation technology. Referring to the characteristics and excellent functions of the composite honeycomb hollow structure, the fiber-metal hybrid laminate is mechanically processed according to the principle of subtractive material technology to obtain an inverse honeycomb sandwich structure, while a filler is added to the concave structure. The purpose is to design and prepare a fiber-metal hybrid laminate with an inverse honeycomb sandwich structure, further reducing the weight of the fiber-metal hybrid laminate. At the same time, the mixed filler with multiple physical properties in the concave honeycomb structure is fully filled in the honeycomb sandwich in a foamed form after thermal curing, ensuring the structural consistency and performance diversity of the fiber-metal hybrid laminate. The foamed form also improves the overall energy absorption and impact resistance of the material, promoting the widespread use of this lightweight, multifunctional material in special aerospace applications.

[0013] The definition is as follows: First, breaking through the traditional additive manufacturing method of honeycomb sandwich structures, innovatively utilizing subtractive manufacturing technology, the machining tool moves along the machining trajectory while performing a certain amount of cutting along the thickness of the sheet, forming a concave hexagonal structure. The unprocessed area material forms a support portion, which, combined with the concave hexagonal structure, forms a concave reverse honeycomb sandwich structure. The overall weight of the material is reduced, and the spatial structure of the reverse honeycomb sandwich structure has certain impact resistance. Then, to improve the bonding quality between the fiber layer and the metal layer and ensure the structural and functional integrity of the fiber-metal hybrid laminate, the surface of the aluminum alloy with the concave hexagonal structure is passivated by phosphoric acid anodization, which increases the mechanical locking force between the metal laminate and the resin. Then, to ensure the multifunctional physical properties of the fiber-metal hybrid laminate and improve its impact resistance, a high-temperature expander, a physical filler, and an epoxy resin are mixed to form a viscous mixture that easily fills the concave hexagonal structure and realizes the multifunctional properties of the material. Then, according to the designed and optimized fiber-metal hybrid laminate structure and fiber prepreg layup method, the number of panels is selected, and the fiber prepreg layup technology is used to form a prefabricated fiber-metal hybrid laminate. The fiber-metal hybrid laminate structure can be 1 / 2, 2 / 3, 3 / 4, or 5 / 6. The fiber prepreg layup method can be unidirectional ply (0° / 0° layup), orthogonal ply (0° / 90° layup), and orthogonal ply (+45° / -45°). Finally, the prefabricated fiber-metal hybrid laminate is fabricated into a vacuum bag system. Vacuuming is performed to reduce the gas between the fiber layer and the metal layer to ensure a dense composite laminate during the thermal curing process. The vacuum bag system containing the prefabricated fiber-metal hybrid laminate is placed in an autoclave. By setting the appropriate temperature and pressure, the fiber layer is cured and the fiber layer and the metal layer are bonded, thus obtaining a dense and complete fiber-metal hybrid laminate. The high-temperature expansion agent expands under the action of appropriate temperature and fully fills the inverse honeycomb structure together with the multi-physical property filler. The viscous foam-like mixed filler not only helps to improve the impact resistance of the material, but also has multi-object functional properties, realizing the integrated design and manufacturing of functional structures.

[0014] In response to the urgent need for lightweight, multifunctional materials for aircraft with greater maneuverability and superior stealth, this paper, based on the design and fabrication of lightweight material structures, combines honeycomb sandwich structure design methods with glass fiber reinforced aluminum alloy laminates. Utilizing subtractive material processing principles and metal precision machining processes, a honeycomb sandwich structure is easily obtained. By selecting the filler composition and optimizing the sandwich structure, the lightweight, multifunctional fiber-metal hybrid laminate not only has important applications in the aerospace field, but also has huge market potential in future marine applications and new energy vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The present invention provides a fiber-metal hybrid laminate with an inverse honeycomb sandwich structure and a preparation method thereof;

[0016] Figure 2 The present invention provides a machining process for the reverse honeycomb sandwich structure with an inwardly concave aluminum alloy layer;

[0017] Figure 3 The surface treatment process of the aluminum alloy plate with the concave reverse honeycomb sandwich structure provided by the present invention;

[0018] Figure 4 The present invention provides a process for preparing a prefabricated fiber-metal hybrid laminate with a concave reverse honeycomb sandwich structure filler;

[0019] Figure 5 The invention provides a vacuum bag-autoclave thermal curing process for prefabricated fiber-metal hybrid laminates.

[0020] In the figure: 1-aluminum alloy upper plate, 2-aluminum alloy lower plate, 3-aluminum alloy upper plate with concave hexagonal structure, 4-aluminum alloy lower plate with concave hexagonal structure, 5-support part, 6-concave hexagonal structure, 7-alkaline washing process, 8-acid washing process, 9-phosphoric acid anodizing process, 10-surface-treated aluminum alloy upper plate, 11-surface-treated aluminum alloy lower plate, 12-chemically treated metal local structure surface morphology, 13-fiber prepreg, 14-viscous mixture, 15-prefabricated fiber-metal hybrid laminate, 16-vacuum bag, 17-autoclave. DETAILED DESCRIPTION

[0021] The fiber-metal hybrid laminate with an inverse honeycomb sandwich structure and the preparation method thereof provided by the present invention are described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] like Figure 1 — Figure 5 As shown, the present invention provides a fiber-metal hybrid laminate with an inverse honeycomb sandwich structure and a preparation method thereof, comprising the following steps performed in sequence:

[0023] 1) First, an aluminum alloy upper plate (1) and an aluminum alloy lower plate (2) are arranged and placed by aligning their edges, a hexagonal processing track is carved on the same position of the inner surface of the multi-layer aluminum alloy plate, and a subtractive machining method is adopted. While the machining tool moves along the machining track, a certain amount of cutting processing is performed along the thickness of the plate to form a concave hexagonal structure (6), thereby obtaining an aluminum alloy upper plate (3) with a concave hexagonal structure and an aluminum alloy lower plate (4) with a concave hexagonal structure.

[0024] 2) The inner surface of the machined aluminum alloy plate is subjected to a surface chemical treatment, where acetone is used to remove oil stains from the surface of the machined metal part, and then the surface is subjected to a phosphoric acid anodizing treatment, which includes, in sequence, alkaline cleaning (7), acid cleaning (8), and phosphoric acid anodizing (9). The purpose is to obtain an uneven surface structure (12) of the aluminum alloy, increase the surface roughness, and thereby improve the mechanical locking force between the aluminum alloy plate and the resin.

[0025] 3) A high-temperature expansion agent is mixed with a multi-physical property filler, and epoxy resin is added to form a viscous mixture (14), which is then filled into the concave hexagonal structure (6) of the surface-treated aluminum alloy upper plate (10) and the surface-treated aluminum alloy lower plate (11).

[0026] 4) According to actual working conditions, a fiber-metal hybrid laminate structure scheme and a laying method of the fiber prepreg (13) are designed and formulated, and the fiber layer and the metal layer are bonded and combined by manual laying to obtain a prefabricated fiber-metal hybrid laminate (15).

[0027] 5) The prefabricated fiber-metal hybrid laminate (15) obtained in step 4) is made into a vacuum bag system (16), and then placed in an autoclave (17). By setting a suitable temperature T and pressure P, the fiber prepreg is cured and firmly bonded to the aluminum alloy laminate to form a dense fiber-metal hybrid laminate.

Claims

1. A method for preparing a fiber-metal hybrid laminate with an inverse honeycomb sandwich structure, characterized by: It involves the following steps in order: 1) First, an aluminum alloy upper plate (1) and an aluminum alloy lower plate (2) are arranged and placed by aligning their edges, a hexagonal processing track is carved on the same position of the inner surface of the multi-layer aluminum alloy plate, and a subtractive machining method is adopted. While the machining tool moves along the machining track, a certain amount of cutting is performed along the thickness of the plate to form a concave hexagonal structure (6), thereby obtaining an aluminum alloy upper plate (3) with a concave hexagonal structure and an aluminum alloy lower plate (4) with a concave hexagonal structure; 2) chemically treating the inner surfaces of the machined aluminum alloy upper and lower plates, removing oil stains from the machined metal surfaces with acetone, and then performing phosphoric acid anodizing treatment on the surfaces, which includes, in sequence, alkaline washing (7), acid washing (8), and phosphoric acid anodizing (9), in order to obtain an uneven surface structure (12) of the aluminum alloy, increase surface roughness, and thereby improve the mechanical locking force between the aluminum alloy plate and the resin; 3) mixing a high-temperature expansion agent with a multi-physical property filler, adding epoxy resin to form a viscous mixture (14), and filling the mixture into the concave hexagonal structure (6) of the surface-treated aluminum alloy upper plate (10) and the surface-treated aluminum alloy lower plate (11); 4) bonding and combining the fiber prepreg with the aluminum alloy upper plate and the lower plate by manual placement to obtain a prefabricated fiber-metal hybrid laminate (15), wherein the fiber prepreg is located between the aluminum alloy upper plate and the lower plate, and the surfaces of the aluminum alloy upper plate and the lower plate with the concave hexagonal structure are connected to the fiber prepreg; 5) The prefabricated fiber-metal hybrid laminate (15) obtained in step 4) is made into a vacuum bag system (16), and then placed in an autoclave (17). By setting a suitable temperature T and pressure P, the fiber prepreg is cured and firmly bonded to the aluminum alloy laminate to form a dense fiber-metal hybrid laminate; The operating temperature of the high-temperature expansion agent is consistent with the thermal curing temperature range of the fiber-metal hybrid laminate, ensuring that the fiber prepreg is thermally cured. When the fiber layer and the aluminum alloy upper and lower plates form a dense structure, the expansion agent can fill the concave hexagonal structure of the upper and lower plates to the maximum extent.

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