A lightweight composite sandwich wing rib and method of manufacture

Abstract

The application provides a light composite sandwich wing rib and a preparation method, and relates to the technical field of aircraft manufacturing, and comprises a wing rib outer contour and at least two inclined web pipes. The inside of the wing rib outer contour is a hollow structure, the inclined web pipes are arranged in the hollow structure, the two ends of the inclined web pipes are fixedly connected with opposite sides of the wing rib outer contour respectively, and the two adjacent inclined web pipes and the wing rib outer contour form a triangular structure. The wing rib outer contour comprises a wing rib edge strip and a wing rib web plate. The wing rib web plate forms an outer frame of the wing rib outer contour, and the wing rib edge strip covers the aerodynamic side of the wing rib web plate. After a reinforcing material is filled in a cavity formed by the wing rib edge strip and the wing rib web plate, a reinforced filling area is formed. The reinforcing material between the wing rib web plate and the wing rib edge strip made of composite materials and the inclined web pipes used for reinforcement reduce the weight of the whole wing rib while ensuring the effective strength of the wing rib, and are suitable for light aircraft such as solar aircraft.

Description

Technical Field

[0001] This invention relates to the field of aircraft manufacturing technology, specifically to a lightweight composite material sandwich wing rib and its preparation method. Background Technology

[0002] Traditional aircraft wing structures are mainly single-spar or multi-spar structures. The spar extends laterally relative to the longitudinal axis of the aircraft fuselage to support multiple longitudinally extending, laterally spaced ribs, while the spar is connected to the fuselage. The rib webs of the aircraft wing can bear tensile and compressive loads to maintain the airfoil. Among them, truss rib design is one of the effective methods to transfer and distribute loads in the integral wing.

[0003] In recent years, solar-powered aircraft, due to their use of green energy, have become one of the main development directions of the aviation industry. Compared with metals, composite materials can also be used to manufacture high-strength and lightweight truss ribs, making them more suitable for solar-powered aircraft. However, current composite truss ribs have the following problems: First, the preparation and assembly of truss ribs are complex; second, to provide sufficient load transfer between truss structures, rib designs are generally heavy, while ordinary foam sandwich ribs, although able to reduce weight, have limited load-bearing capacity; third, truss ribs usually use metal components to connect the truss structure, which not only increases the weight of the wing ribs but also causes problems such as galvanic corrosion. Summary of the Invention

[0004] In view of this, the embodiments of this specification provide a lightweight composite sandwich rib and a method for its preparation, so as to achieve excellent rigidity and stability of the rib while maintaining a sufficiently low structural weight.

[0005] The embodiments in this specification provide the following technical solutions:

[0006] A lightweight composite sandwich rib, comprising:

[0007] The outer contour of the wing rib and at least two oblique web tubes are provided. The interior of the outer contour of the wing rib is a hollow structure. The oblique web tubes are set in the hollow structure. The two ends of the oblique web tubes are fixedly connected to the opposite side of the outer contour of the wing rib. The two adjacent oblique web tubes and the outer contour of the wing rib form a triangular structure.

[0008] The outer contour of the rib includes the rib flange and the rib web. The rib web forms the outer frame of the outer contour of the rib. The rib flange covers the aerodynamic side of the rib web. After the cavity formed by the rib flange and the rib web is filled with reinforcing material, a reinforced filling area is formed.

[0009] Furthermore, the wing rib flange extends outward from the web of the wing rib, and the cross-section of the outer contour of the wing rib is T-shaped.

[0010] Furthermore, the diameter of the oblique web tube is consistent with the thickness of the outer contour of the wing rib.

[0011] Furthermore, both the flange strip and the web of the flange include a first composite material ply, which is one or more combinations of staggered 0° ply, 90° ply, -45° ply, and 45° ply.

[0012] Furthermore, the inclined web tube includes a second composite material layup, which is one or more combinations of staggered 0° layups and 90° layups.

[0013] A method for preparing a lightweight composite sandwich rib, the method comprising the following steps:

[0014] Following the layup sequence of the second composite material, the preform of the inclined web tube is prepared by laying the prepreg layer by layer. The preform of the inclined web tube is cured and demolded in an oven to obtain the pre-cured inclined web tube.

[0015] In the wing rib outer contour assembly molding mold, the wing rib outer contour prepreg is laid layer by layer according to the layup sequence of the first composite material layer to form a preform of the wing rib outer contour, and the cavity formed by the wing rib flange and wing rib web is filled with reinforcing material.

[0016] Place the pre-cured oblique web tube in the hollow structure of the outer contour of the wing rib, so that the two ends of the pre-cured oblique web tube abut against the opposite sides of the outer contour of the wing rib.

[0017] After the first wing rib outer contour forming mold and the second wing rib outer contour forming mold are joined together, the forming auxiliary material is wrapped on the side of the wing rib outer contour forming mold and then sealed with a vacuum bag. The wing rib outer contour forming mold is then placed in a hot autoclave for heating and pressurization. The inclined web tube and the wing rib outer contour are cured into one piece through the connecting nodes by a stepped curing process.

[0018] After the cured ribs are shaped, lightweight composite sandwich ribs are obtained.

[0019] Furthermore, the stepped curing process includes initial heating, initial heat preservation, secondary heating, secondary heat preservation, and cooling. The glass transition temperature of the inclined web tube is higher than the curing temperature of the prepreg on the outer contour of the rib.

[0020] Furthermore, it also includes:

[0021] Based on the load and overload conditions of the ribs, the number of oblique web tubes and the angle between the oblique web tubes and the outer contour of the ribs are determined through topology optimization.

[0022] Based on the load on the ribs, determine the laying sequence and thickness of the first composite material ply of the outer contour of the ribs and the laying sequence and thickness of the second composite material ply of the oblique web tube.

[0023] Furthermore, the rib outer contour prepreg and the oblique web tube prepreg are both continuous fiber prepregs, the continuous fiber being one or more combinations of carbon fiber and glass fiber, the prepreg being one or more combinations of epoxy resin and bismaleimide resin, and the reinforcing material being one or more combinations of PMI foam, PU foam, and NOMAX honeycomb.

[0024] Furthermore, when the first wing rib outer contour forming mold and the second wing rib outer contour forming mold are closed, a thickness shim is placed in the first shim receiving hole of the first wing rib outer contour forming mold, and the second wing rib outer contour forming mold is covered over the first wing rib outer contour forming mold, so that the thickness shim is inserted into the second shim receiving hole of the second wing rib outer contour forming mold.

[0025] Compared with the prior art, the beneficial effects that at least one technical solution adopted in the embodiments of this specification can achieve include at least:

[0026] By using composite material to reinforce the space between the wing rib web and the wing rib flange, as well as the inclined web tubes for reinforcement, the overall weight of the wing rib is reduced while ensuring the effective strength of the wing rib. This method is suitable for light aircraft such as solar-powered aircraft. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the overall structure of the lightweight composite material sandwich rib according to an embodiment of the present invention;

[0029] Figure 2 yes Figure 1 A schematic diagram of the cross-section of AA;

[0030] Figure 3 This is a side view of a portion of the outer contour of the wing rib in an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the composite material layup of the wing rib flange and wing rib web in an embodiment of the present invention;

[0032] Figure 5 This is a schematic diagram of the plying of the oblique web tubes according to an embodiment of the present invention;

[0033] Figure 6 This is a schematic diagram of the connection node structure of the lightweight composite sandwich rib according to an embodiment of the present invention;

[0034] Figure 7 This is a schematic diagram of the lightweight composite material sandwich ribs placed in the rib outer contour assembly molding mold according to an embodiment of the present invention;

[0035] Figure 8 This is a schematic diagram of the structure of the first wing rib outer contour forming mold and the second wing rib outer contour forming mold according to an embodiment of the present invention;

[0036] Figure 9 This is a schematic diagram of the mold closing of the first wing rib outer contour forming mold and the second wing rib outer contour forming mold according to an embodiment of the present invention;

[0037] Figure 10 This is a strain distribution diagram of the ribs in the topology optimization of this invention embodiment;

[0038] Figure 11 This is a stress distribution diagram of the ribs in the topology optimization of this invention.

[0039] Explanation of reference numerals in the attached drawings: 1. Rib flange; 2. Rib web; 3. Inclined web tube; 4. Reinforced filling area; 5. Connection node; 6. Rib outer contour assembly forming mold; 601. First rib outer contour forming mold; 6011. First gasket receiving hole; 602. Second rib outer contour forming mold; 6021. Second gasket receiving hole; 603. Thickness gasket. Detailed Implementation

[0040] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0041] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0042] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0043] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The drawings only show the components related to this application and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0044] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0045] The technical solutions provided by the various embodiments of this application are described below with reference to the accompanying drawings.

[0046] like Figure 1 , Figure 2 and Figure 3 As shown, the lightweight composite sandwich rib includes: an outer rib contour and at least two oblique web tubes 3. The interior of the outer rib contour is a hollow structure, and the oblique web tubes 3 are disposed within the hollow structure. The two ends of the oblique web tubes 3 are fixedly connected to opposite sides of the outer rib contour, and two adjacent oblique web tubes 3 form a triangular structure with the outer rib contour. The outer rib contour includes rib flange strips 1 and rib web plates 2. The rib web plates 2 form the outer frame of the outer rib contour, and the rib flange strips 1 cover the aerodynamic side of the rib web plates 2. After filling the cavity formed by the rib flange strips 1 and the rib web plates 2 with reinforcing material, a reinforced filling area 4 is formed. The rib flange strips 1 extend outwards along the rib web plates 2, making the cross-section of the outer rib contour T-shaped.

[0047] The diameter of the oblique web tube 3 is consistent with the thickness of the outer contour of the rib. The central axis of the oblique web tube 3 is located on the longitudinal mid-surface of the rib web plate 2 to ensure that the oblique web tube 3 has no additional bending moment relative to the composite material sandwich rib.

[0048] Both the wing rib flange 1 and the wing rib web 2 include a first composite material ply, which is one or more combinations of staggered 0° ply, 90° ply, -45° ply, and 45° ply. Figure 4 As shown, in some embodiments, the layup sequence of the first composite material ply from the inside out is 0° ply, 90° ply, -45° ply, and 45° ply. In other embodiments, the layup sequence of the first composite material ply from the inside out is 90° ply, 0° ply, 45° ply, and -45° ply. The outermost 45° and -45° plies are used to withstand out-of-plane torsional loads, the middle 90° ply is used to withstand lateral loads, and the innermost 0° ply is used to withstand axial loads. The order of the plies that withstand out-of-plane torsional loads can be changed, and the order of the plies that withstand lateral / axial loads can be changed.

[0049] The oblique web tube 3 includes a second composite material ply, which is one or more combinations of staggered 0° plies and 90° plies. Figure 5 As shown, in some embodiments, the layup sequence of the second composite material ply from the inside out is 0° ply followed by 90° ply. In other embodiments, the layup sequence of the first composite material ply from the inside out is 90° ply followed by 0° ply. The 90° ply is used to bear lateral loads, and the 0° ply is used to bear axial loads. The order of the plies bearing lateral / axial loads can be changed.

[0050] like Figure 6 As shown, no adhesive film is needed in the molding of the oblique web tube 3 and the wing rib web plate 2. Part of the resin in the 35wt% high resin content prepreg flows and impregnates the joint, ensuring the overall connection strength between the oblique web tube 3 and the wing rib web plate 2.

[0051] A method for preparing a lightweight composite sandwich rib includes the following steps:

[0052] The first step is to lay the pre-molded body of the inclined web tube 3 by laying the pre-impregnated material layer by layer according to the laying sequence of the second composite material. After curing and demolding the pre-molded body of the inclined web tube 3 in an oven, the pre-cured inclined web tube 3 is obtained.

[0053] The second step is to lay the wing rib outer contour prepreg layer by layer in the wing rib outer contour assembly mold 6 according to the layup sequence of the first composite material layer to form a preform of the wing rib outer contour, and fill the cavity formed by the wing rib edge strip 1 and the wing rib web 2 with reinforcing material.

[0054] Specifically, each layer in the first composite material layup of the rib flange 1 and the rib web 2 is covered with the same prepreg, so that the fibers used for the main load-bearing of the rib flange 1 and the rib web 2 remain continuous, ensuring the overall stiffness and strength of the rib.

[0055] Specifically, both the rib outer contour prepreg and the inclined web tube prepreg are continuous fiber prepregs. The continuous fibers are one or more combinations of carbon fiber and glass fiber, the prepreg is one or more combinations of epoxy resin and bismaleimide resin, and the reinforcing material is one or more combinations of PMI foam, PU foam, and NOMAX honeycomb. The advantage of continuous fiber reinforced composite materials (continuous fiber prepregs) lies in the designability of the layup, which can be efficiently tailored to the type of load it bears, and its specific stiffness and specific strength are higher than those of traditional metal materials. Continuous fiber prepregs consist of fibers (main load-bearing) and resin (load-transferring).

[0056] Specifically, in one embodiment, the rib profile prepreg is made of a single sheet of T700 carbon fiber reinforced epoxy resin.

[0057] In one embodiment, both the rib profile prepreg and the oblique web prepreg include one or more of unidirectional tape prepreg and fabric prepreg, and the prepreg has an areal density of 100±1 g / m². 2 The ultra-thin prepreg has a resin content of 35±0.1wt%.

[0058] Step 3, as follows Figure 7 As shown, the pre-cured oblique web tube 3 is placed in the hollow structure of the outer contour of the wing rib, so that the two ends of the pre-cured oblique web tube 3 abut against the opposite sides of the outer contour of the wing rib.

[0059] Step 4: After the first wing rib outer contour forming mold 601 and the second wing rib outer contour forming mold 6 are closed, the molding auxiliary material is wrapped on the side of the wing rib outer contour forming mold 6 and sealed with a vacuum bag. The wing rib outer contour forming mold 6 is then placed in a thermostatic jar for heating and pressurization. The inclined web tube 3 and the wing rib outer contour are cured into one piece through the connecting node 5 by a stepped curing process.

[0060] like Figure 8 and Figure 9 As shown, when the first wing rib outer contour forming mold 601 and the second wing rib outer contour forming mold 602 are closed, the thickness shim 603 is placed in the first shim receiving hole 6011 of the first wing rib outer contour forming mold 601, and the second wing rib outer contour forming mold 602 is covered to the first wing rib outer contour forming mold 601, so that the thickness shim 603 is inserted into the second shim receiving hole 6021 of the second wing rib outer contour forming mold 602.

[0061] In some embodiments, an 11.4mm thick shim 603 is placed on the top surface of the first rib outer contour forming mold 601, and the second rib outer contour forming mold 602 is assembled and fixed to the rib outer contour combined forming mold 6, so that the oblique web tube 3 and the rib outer contour are kept as a whole.

[0062] Specifically, since the outer surface of the wing rib flange 1 in the embodiment of the present invention is an aerodynamic surface, and the wing rib flange 1 and the wing rib web 2 form a closed angle, in order to ensure smooth mold closing and demolding processes, the base plates of the first wing rib outer contour forming mold 601 and the second wing rib outer contour forming mold 6 in this embodiment are divided into several sub-modules, and each sub-module is connected by a positioning pin; in order to reduce heat deformation caused by repeated use, the first wing rib outer contour forming mold 601 and the second wing rib outer contour forming mold 602 are both made of mold steel.

[0063] Specifically, the molding accessories include release fabric, breathable felt, and vacuum bags. The release fabric, breathable felt, and vacuum bags are sequentially wrapped around the outside of the wing rib outer contour assembly molding mold 6.

[0064] Specifically, stepped curing includes initial heating, initial holding, secondary heating, secondary holding, and cooling. Stepped curing allows for control of resin flow and impregnation processes based on the resin's viscosity-temperature characteristics, which is beneficial for molding low-porosity, high-performance lightweight composite sandwich ribs. During the initial heating, the temperature is increased from room temperature to 80℃ at a rate of 20±5℃ / h; this temperature is then held at 80℃ for 1 hour. During the secondary heating, the temperature is increased from 80℃ to 120℃ at a rate of 20±5℃ / h; this temperature is then held at 120℃ for 2 hours. During cooling, the temperature is reduced from 120℃ to room temperature at a rate of 30±5℃ / h, completing the curing process. Furthermore, during the heating and pressurization process, a curing pressure of 0.20 MPa and a vacuum pressure of ≥-0.09 MPa are maintained. During the prepreg laying process, 2 to 4 room temperature pre-compaction processes are required to expel air between the prepreg layers and compact the layers to improve the interlayer and interface strength. The room temperature is 15 to 30°C, the pre-compaction pressure is ≥-0.09MPa, and the pre-compaction time is 10 to 20 minutes.

[0065] Step 5: After the cured ribs are shaped, lightweight composite sandwich ribs are obtained.

[0066] Specifically, the ribs are cut to net dimensions using CNC machining to obtain lightweight composite sandwich ribs.

[0067] Before preparing the lightweight composite sandwich ribs, it is necessary to first determine the laying sequence and thickness of the first composite material ply of the outer contour of the ribs and the laying sequence and thickness of the second composite material ply of the inclined web tube 3.

[0068] Specifically, the tiling sequence is determined through the following steps:

[0069] Based on the load and overload input of the rib, the number of oblique web tubes 3 and the angle between the oblique web tubes 3 and the outer contour of the rib are determined through topology optimization; based on the load and overload of the rib, the laying sequence and thickness of the first composite material ply of the outer contour of the rib and the laying sequence and thickness of the second composite material ply of the oblique web tube 3 are determined.

[0070] In one embodiment, such as Figure 1 The wing ribs in the lightweight composite sandwich ribs have an overall length of 660mm, a width of 20mm, and a height of approximately 330mm. The thickness of the wing rib flange 1 is 0.5mm. The overall thickness of the wing rib web 2 is 11.4mm, of which the thickness of the first composite material layup is 0.2mm and the thickness of the reinforcing filling area 4 is 11mm. The outer diameter of the inclined web tube 3 is 11mm, and its thickness is 0.5mm. The length of the first inclined web tube is 330mm, the length of the second inclined web tube is 320mm, and the length of the third inclined tie tube is 265mm. The connection length between the inclined tie tube and the web is 20mm. Both the wing rib flange 1 and the wing rib web 2 are made of ultra-thin T700 carbon fiber reinforced epoxy resin prepreg, and the density of the carbon fiber is 100±1g / m³. 2 The reinforced epoxy resin content is 35±0.1wt%, making it a high-resin-content prepreg; the reinforced filler zone 4 has a density of 51kg / m³. 3 The machined PMI foam block. After topology optimization, the strain and stress distribution of the ribs in the embodiment are as follows: Figure 10 and Figure 11 As shown.

[0071] Beneficial effects of the embodiments of the present invention:

[0072] By adding reinforcing material between the composite rib web and rib flange made of continuous fiber reinforced prepreg, and supplementing it with continuous fiber oblique web tubes for effective support, this composite sandwich rib design can fully utilize the high specific strength load-bearing advantage of fibers while reducing structural weight. This gives the rib excellent overall rigidity and stability, enabling it to effectively transfer and distribute loads when applied to aircraft wings, especially suitable for light aircraft such as solar-powered aircraft. The number, position, and relative angle of the oblique web tubes can be designed according to the strain and stress distribution of the rib, improving the overall structural efficiency and controlling structural weight. Each ply of the rib flange and rib web is covered by the same prepreg, ensuring continuous load-bearing between the fibers of the rib flange and rib web, guaranteeing the stiffness and strength of the rib. No adhesive film is needed during the molding of the oblique web tubes and rib web, reducing the weight of the adhesive film. Part of the resin in the high resin content prepreg flows and impregnates the joint, ensuring the overall connection strength between the oblique web tubes and rib web.

[0073] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In particular, the method embodiments described later are relatively simple in description because they correspond to the system; relevant parts can be referred to the descriptions in the system embodiments.

[0074] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A lightweight composite material sandwich rib, characterized in that, include: The outer contour of the wing rib and at least two oblique web tubes (3) are provided. The interior of the outer contour of the wing rib is a hollow structure. The oblique web tubes (3) are set in the hollow structure. The two ends of the oblique web tubes (3) are fixedly connected to the opposite side of the outer contour of the wing rib. The two adjacent oblique web tubes (3) and the outer contour of the wing rib form a triangular structure. The outer contour of the rib includes a rib flange (1) and a rib web (2). The rib web (2) forms the outer frame of the outer contour of the rib. The rib flange (1) covers the aerodynamic side of the rib web (2). After the cavity formed by the rib flange (1) and the rib web (2) is filled with reinforcing material, a reinforcing filling area (4) is formed. The wing rib flange (1) extends outward from the wing rib web (2), and the cross-section of the outer contour of the wing rib is T-shaped; Both the wing rib flange (1) and the wing rib web (2) include a first composite material ply, which is one or more combinations of staggered 0° ply, 90° ply, -45° ply, and 45° ply; Each of the first composite material layups of the wing rib (1) and the wing rib web (2) is covered with the same prepreg, so that the fibers for the main load-bearing of the wing rib (1) and the wing rib web (2) remain continuous.

2. The lightweight composite sandwich rib according to claim 1, characterized in that, The diameter of the oblique web tube (3) is consistent with the thickness of the outer contour of the wing rib.

3. The lightweight composite sandwich rib according to claim 1, characterized in that, The oblique web tube (3) includes a second composite material ply, which is one or more combinations of staggered 0° plies and 90° plies.

4. A method for preparing a lightweight composite sandwich rib, used to prepare the lightweight composite sandwich rib according to any one of claims 1 to 3, characterized in that, The preparation method includes the following steps: According to the laying sequence of the second composite material, the preform of the oblique web tube (3) is made by laying the oblique web tube prepreg layer by layer. The preform of the oblique web tube (3) is cured and demolded in an oven to obtain the pre-cured oblique web tube (3). In the wing rib outer contour assembly molding mold (6), the wing rib outer contour prepreg is laid layer by layer according to the layup sequence of the first composite material, and the wing rib outer contour prepreg is made into a preform, and the cavity formed by the wing rib flange (1) and the wing rib web (2) is filled with reinforcing material. The pre-cured oblique web tube (3) is placed in the hollow structure of the outer contour of the wing rib, so that the two ends of the pre-cured oblique web tube (3) abut against the opposite sides of the outer contour of the wing rib. After the first wing rib outer contour forming mold (601) and the second wing rib outer contour forming mold (6) are closed, the molding auxiliary material is wrapped on the side of the wing rib outer contour forming mold (6), and then sealed with a vacuum bag. The wing rib outer contour forming mold (6) is placed in a hot autoclave for heating and pressurization. The inclined web tube (3) and the wing rib outer contour are solidified into one piece through the connecting node (5) by step-like curing. After the cured ribs are shaped, composite sandwich ribs are obtained.

5. The method for preparing composite sandwich ribs according to claim 4, characterized in that, The stepped curing process includes initial heating, initial heat preservation, secondary heating, secondary heat preservation, and cooling. The glass transition temperature of the inclined web tube is higher than the curing temperature of the prepreg on the outer contour of the rib.

6. The method for preparing lightweight composite sandwich ribs according to claim 4, characterized in that, Also includes: Based on the load and overload of the ribs, the number of oblique web tubes (3) and the angle between the oblique web tubes (3) and the outer contour of the ribs are determined through topology optimization. Based on the load of the rib, determine the laying sequence and thickness of the first composite material ply of the outer contour of the rib and the laying sequence and thickness of the second composite material ply of the oblique web tube (3).

7. The method for preparing lightweight composite sandwich ribs according to claim 4, characterized in that, Both the rib outer contour prepreg and the oblique web tube prepreg are continuous fiber prepregs. The continuous fiber is one or more combinations of carbon fiber and glass fiber. The prepreg is one or more combinations of epoxy resin and bismaleimide resin. The reinforcing material is one or more combinations of PMI foam, PU foam, and NOMAX honeycomb.

8. The method for preparing lightweight composite sandwich ribs according to claim 4, characterized in that, When the first wing rib outer contour forming mold (601) and the second wing rib outer contour forming mold (602) are closed, the thickness shim (603) is placed in the first shim receiving hole (6011) of the first wing rib outer contour forming mold (601), and the second wing rib outer contour forming mold (602) is covered to the first wing rib outer contour forming mold (601), so that the thickness shim (603) is inserted into the second shim receiving hole (6021) of the second wing rib outer contour forming mold (602).

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