Integrated forming method and structure for keel beam and ship bottom of ground effect aircraft

Abstract

The invention belongs to the field of aircraft part manufacturing, and discloses an integrated forming method and structure for a keel beam and a ship bottom of a ground effect aircraft, and the forming method comprises the steps of ship bottom pre-curing, combined core preparation, combined core positioning, keel beam composite material layer laying and pasting, and vacuum bag pressing co-bonding curing. The structure comprises a composite material ship bottom and an n-shaped keel beam, the keel beam comprises a combined core and a keel beam composite material laying layer structure which is tightly solidified on the periphery of the combined core, the outer contour of the combined core is attached to the curved surface of the inner side of the ship bottom, and the combined core is formed by alternately connecting full-height shape follow-up foam blocks and shape follow-up carbon plates. The adaptability and the connection reliability of a traditional keel beam and a ship bottom assembly process are improved, meanwhile, the structure light weight and high rigidity are considered, the structure load transmission is efficient, the structure stability is excellent, the process is simplified, the method is suitable for industrial production, and the method is suitable for the complex working condition requirements of ground effect aircrafts.

Description

Technical Field

[0001] This invention relates to the field of aircraft component manufacturing, specifically to an integrated molding method for the keel beam and bottom of a ground effect vehicle, and the integrated load-bearing structure obtained by the method. Background Technology

[0002] With its core advantages of high-speed navigation close to the ground / water, amphibious mobility, large payload, and low fuel consumption, combined with the unique flight characteristics brought by the ground effect, ground effect vehicles have applications covering both military and civilian sectors.

[0003] Ground effect vehicles (GEVs) are subjected to aerodynamic lift and longitudinal bending forces during flight, and to hydrodynamic impact and wave pounding forces during water skimming / takeoff and landing. During amphibious operations, they are also subjected to friction and impact forces from the ground / tidal flats. As the main longitudinal beam load-bearing structure at the bottom of the GEV fuselage, the keel beam is the main carrier and transfer carrier of these complex loads and the "bottom spine" of the overall fuselage structure, directly determining the safety and service life of the entire aircraft. Composite materials, with their advantages of high strength, lightweight and corrosion resistance, have gradually become the core material for the keel beam.

[0004] To match the low-altitude aerodynamic layout, the composite material keel beam needs to be matched with the hull profile using a variable cross-section, smooth curved surface transition, and multi-branch integrated structure. When manufacturing the keel beam with the above structure, it is necessary to design a special complex molding mold corresponding to it. The mold manufacturing cost is high, the versatility is poor, and it is easy to deform, which affects the quality and precision of the product. In addition, the traditional composite material molding and autoclave molding processes are not well adapted to the complex and large-sized structural features of the keel beam, making the process difficult. The resulting keel beam products have poor stability and low reliability of process connection with the hull.

[0005] Therefore, how to reduce manufacturing costs, improve the quality and precision of the keel beam, and ensure the reliability of the connection between the keel beam and the bottom of the ship have become urgent problems to be solved. Summary of the Invention

[0006] Therefore, the purpose of this invention is to provide an integrated molding method and structure for the keel beam and the bottom of a ground effect vehicle, so as to solve the problems of insufficient adaptability of traditional molding processes to the complex structure of the keel beam, high cost and easy deformation of parts and molds, and low reliability of the connection between the bottom and the keel beam.

[0007] This invention provides a method for the integrated molding of the keel beam and the bottom of a ground effect vehicle, comprising the following steps:

[0008] Pre-curing of the ship bottom: The composite material paving material is laid and cured to produce a composite material ship bottom, wherein the inner side of the ship bottom is a continuous curved surface;

[0009] Composite core fabrication: Based on the design height of the zigzag cross-section of the keel beam of the ground effect vehicle and the design contour of the inner curved surface of the bottom, a composite core is fabricated, wherein the composite core includes full-height conformal foam blocks and conformal carbon plates alternately connected along the length of the keel beam;

[0010] Combination core positioning: The combination core is positioned conformally on the inner curved surface of the ship bottom;

[0011] Keel beam composite material layup: Keel beam composite material is continuously laid along the overall contour of the outer perimeter of the composite core and the inner curved surface of the ship bottom.

[0012] Vacuum bag pressure co-bonding curing: The keel beam composite material layup is cured by vacuum bag pressure co-bonding process, realizing the synchronous co-bonding and curing of the keel beam composite material layup with the ship bottom and the keel beam composite material layup with the composite core, resulting in an integrated load-bearing structure of the keel beam and the ship bottom.

[0013] Preferably, the composite material lining material for the ship bottom is a medium-temperature resin system composite prepreg or a composite woven fabric for dry-wet hand lay-up.

[0014] Further preferably, the full-height conformal foam block is a PMI high-strength foam block, which is formed by mechanical processing.

[0015] Further preferably, the conformal carbon plate is a 4mm-6mm carbon fiber plate, formed by mechanical processing.

[0016] In a further preferred embodiment, the full-height conformal foam block and conformal carbon plate are alternately connected along the length of the keel beam by structural adhesive bonding to form a zigzag composite core.

[0017] In a further preferred embodiment, the composite core is conformally attached to the inner curved surface of the ship's bottom using structural adhesive and then cured and connected.

[0018] Further preferably, the composite material paving material for the keel beam is a medium-temperature resin system composite prepreg or a composite woven fabric laid using a dry-wet hand lay-up method.

[0019] Further optimization involves the following steps for vacuum bag pressure co-bonding and curing:

[0020] The bottom of the ship, with the composite core positioned and the keel beam composite material layup applied, is placed on the bottom forming mold;

[0021] Sealing tape is pasted on the edge of the bottom molding mold. Then, release cloth, perforated release film and breathable felt are laid in sequence. After sealing with vacuum bag film, the vacuum valve inside the bag is evacuated through the vacuum system to form a negative pressure environment of 0.08~0.1MPa. This allows the keel beam composite material layup to be tightly pressed onto the outer periphery of the composite core and the inner curved surface of the bottom under negative pressure. Then, the temperature is raised for curing. The resin adhesive on the keel beam composite material layup or the resin adhesive of wet hand layup is used to achieve synchronous co-bonding and curing of the keel beam composite material layup with the bottom and the keel beam composite material layup with the composite core.

[0022] After curing, the auxiliary materials are removed and the surface is polished and repaired to obtain an integrated load-bearing structure of the keel beam and the bottom of the ship.

[0023] This invention also provides an integrated load-bearing structure for a ground effect vehicle's keel beam and bottom, comprising: a bottom and a keel beam integrally formed with the bottom, wherein the bottom is a composite material bottom, the keel beam has a Z-shaped cross-section, the keel beam includes a composite core and a composite material layup structure, the outer contour of the composite core fits the inner curved surface of the bottom, the composite core includes full-height conformal foam blocks and conformal carbon plates alternately connected along the length of the keel beam, and the composite material layup structure of the keel beam is tightly cured to the outer periphery of the composite core and its lower part is tightly cured and connected to the inner curved surface of the bottom.

[0024] Preferably, the keel beam is located at the middle of the bottom of the ground effect vehicle's fuselage and extends from the front end of the fuselage to the rear end.

[0025] The present invention provides an integrated molding method and structure for the keel beam and hull of a ground effect vehicle. It uses a combined core to replace the complex molding mold of the keel beam and achieves integrated molding of the keel beam and hull through a vacuum bag pressing co-bonding process. This solves the problem of high cost of traditional composite material autoclaves and molding, improves the adaptability and connection reliability of traditional keel beam and hull assembly processes, and takes into account both lightweight structure and high rigidity. The structure has efficient load transfer, excellent structural stability, simplified process, and is suitable for industrial production, and is applicable to the complex working conditions of ground effect vehicles. Attached Figure Description

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0027] Figure 1 A schematic diagram of the integrated molding structure of the keel beam and the bottom of the ground effect vehicle provided by the present invention;

[0028] Figure 2 A structural diagram illustrating the integrated molding structure of the keel beam and the bottom of the ground effect vehicle provided by this invention;

[0029] Figure 3This is an exploded view of the composite core. Detailed Implementation

[0030] The present invention will be further explained below with reference to specific implementation schemes, but this explanation does not limit the scope of the invention.

[0031] To achieve a seamless connection between the keel beam and the hull, improve the overall load-bearing capacity of the structure, balance lightweight and high rigidity requirements, and reduce manufacturing costs and assembly difficulty, this invention provides an integrated molding method for the keel beam and hull of a ground effect vehicle. This method uses a composite material hull as the base carrier, and achieves integrated molding of the keel beam and hull through precise positioning of the composite core, covering and applying the composite material layers of the keel beam, and vacuum bag pressing and co-bonding curing. The specific steps are as follows:

[0032] Step 1: Pre-curing of the hull bottom: The hull bottom composite material is laid and cured to obtain the composite material hull bottom. The inner side of the hull bottom is a continuous curved surface adapted to the hydrodynamic layout of the ground effect vehicle, which serves as the reference surface for subsequent molding.

[0033] Preferably, the composite material for the hull is a medium-temperature resin system composite prepreg (such as carbon fiber prepreg) or a composite woven fabric for dry-wet hand lay-up; the lay-up process is medium-temperature resin system composite lay-up or dry-wet hand lay-up; curing can be achieved by vacuum bag pressure curing to form the finished composite material hull.

[0034] Step 2: Composite core preparation: Based on the design height of the zigzag cross section of the ground effect vehicle keel beam and the design contour of the inner curved surface of the bottom, a composite core is prepared. The composite core includes full-height conformal foam blocks and conformal carbon plates that are alternately connected along the length of the keel beam. The composite core is used to replace the molding mold of the composite material keel beam in the prior art and serves as the inner skeleton structure of the final keel beam.

[0035] Preferably, the full-height conformal foam block is a PMI high-strength foam block, which is mechanically formed to conform to the curved surface of the hull; the conformal carbon plate is a 4mm-6mm carbon fiber plate, which is mechanically formed to conform to the curved surface of the hull; the full-height conformal foam block and the conformal carbon plate can be alternately connected along the length of the keel beam by structural adhesive bonding to form a zigzag composite core (the internal skeleton structure of the keel beam).

[0036] Step 3: Positioning of the composite core: The composite core is positioned conformally on the inner curved surface of the hull bottom. Preferably, the composite core can be fixed to the hull bottom with structural adhesive to achieve positioning.

[0037] Step 4: Keel beam composite material layup: The keel beam composite material layup material is continuously laid along the overall contour of the outer perimeter of the composite core and the inner curved surface of the hull bottom. The keel beam composite material layup completely covers the outer perimeter of the composite core and is seamlessly bonded to the inner curved surface of the hull bottom. The keel beam composite material layup material can be a medium-temperature resin system composite prepreg (such as carbon fiber prepreg) or a composite woven fabric laid by dry-wet hand layup to ensure the tightness of the layup with the composite core and the hull bottom.

[0038] Step 5: Vacuum bag pressure co-bonding and curing: The keel beam composite material layup is cured using a vacuum bag pressure co-bonding process to achieve synchronous co-bonding and curing of the keel beam composite material layup with the ship bottom and the keel beam composite material layup with the composite core, resulting in an integrated load-bearing structure of the keel beam and the ship bottom, namely: an integrated composite material structure of "keel beam + ship bottom".

[0039] The vacuum bag pressure bonding molding process uses the negative pressure (vacuum pressure) created by vacuuming to expel air and excess resin from the composite material layup of the keel beam, while simultaneously ensuring that the layers are tightly bonded and the core is formed, achieving resin curing at room temperature or medium to low temperatures.

[0040] The specific method is as follows:

[0041] The bottom of the ship, with the composite core positioned and the keel beam composite material layup applied, is placed on the bottom forming mold;

[0042] Sealing tape is applied to the edge of the bottom molding mold to prevent air leakage. Then, release cloth, perforated release film, and breathable felt are laid in sequence. After sealing with vacuum bag film, the vacuum valve inside the bag is evacuated through the vacuum system to form a negative pressure environment of 0.08~0.1MPa. This allows the keel beam composite material layup to be tightly pressed onto the outer periphery of the composite core and the inner curved surface of the bottom under negative pressure. Then, the temperature is raised for curing. The resin adhesive (or the resin adhesive of wet hand layup) of the keel beam composite material layup is used to achieve synchronous co-bonding and curing of the keel beam composite material layup with the bottom and the composite core.

[0043] After curing, the auxiliary materials are removed and the surface is polished and repaired to obtain an integrated load-bearing structure of the keel beam and the bottom of the ship.

[0044] The integrated molding method for the keel beam and hull of this ground effect vehicle uses a combined core of conformal foam blocks and conformal carbon plates to replace the complex keel beam molding mold. This easily achieves precise molding of the keel beam with variable cross-sections, smooth curved surface transitions, and multi-branch integrated structures, significantly reducing manufacturing costs and simplifying the process. Through a vacuum bag-pressure co-bonding and curing process, the uncured keel beam layup and the finished hull are molded in one step, improving connection reliability, load transfer efficiency, and structural robustness. The combined core features alternating arrangements of full-height conformal foam blocks and conformal carbon plates, with the full-height conformal foam blocks providing... The carbon fiber plate serves to support the hull bottom, improving the overall load transfer capacity of the keel beam while significantly reducing the overall structural weight. It balances the high rigidity of the keel beam with the lightweight requirements of the aircraft. The carbon fiber plate ensures the rigid support of the keel beam and can be positioned to correspond to the fuselage bulkhead, allowing the local water load on the hull bottom to be efficiently transferred to the web of the fuselage bulkhead. The composite core is designed with the inner curved surface of the hull bottom, perfectly adapting to the complex shape of the keel beam. It has high molding precision and good connection performance, effectively dispersing the load, preventing the hull bottom skin from becoming unstable, strengthening the overall structural stability and resistance to deformation, and ensuring the safety and service life of the ground effect vehicle.

[0045] like Figures 1 to 3 As shown, the present invention also provides an integrated load-bearing structure for a ground effect vehicle's keel beam and bottom, which can be prepared using the above method. The integrated load-bearing structure includes: a bottom 200 and a keel beam 100 integrally formed with the bottom 200. The bottom 200 is a composite material bottom. The cross-section of the keel beam 100 is Z-shaped. The keel beam 100 includes a composite core and a composite material layup structure 130. The outer contour of the composite core fits the inner curved surface of the bottom 200. The composite core includes full-height conformal foam blocks 110 and conformal carbon plates 120 alternately connected along the length of the keel beam 100. The composite material layup structure 130 is tightly cured on the outer periphery of the composite core and its lower part is tightly cured and connected to the inner curved surface of the bottom 200.

[0046] The integrated load-bearing structure of the ground effect vehicle's keel beam and hull is rationally designed and easy to manufacture. The composite material keel beam and hull are integrally cured and connected without gaps, resulting in more efficient load transfer and a more robust structure. The composite core features alternating full-height conformal foam blocks and conformal carbon plates. The carbon plates ensure rigid support at key locations on the keel beam (such as the fuselage frame), while the foam blocks provide support for the hull skin, thereby improving the overall structural rigidity and significantly reducing the overall weight. This perfectly balances the high rigidity of the keel beam with the lightweight requirements of the aircraft, allowing it to withstand complex loads without adding extra weight. The composite core's design conforms to the curved surface of the hull, evenly distributing localized impact forces across the entire keel beam and preventing damage from excessive localized stress.

[0047] The keel beam 100 is located at the middle of the bottom of the fuselage 300 of the ground effect vehicle, and extends from the front end of the fuselage 300 to the rear end of the fuselage 300. It provides a longitudinal streamlined ridge structure for the bottom of the fuselage 300, reducing hydrodynamic wave resistance and viscous resistance when gliding at high speed close to the water. At the same time, it allows the water flow to be orderly distributed along both sides of the keel beam 100 of the bottom of the vehicle, avoiding the fuselage drifting and bumping caused by water turbulence.

[0048] The specific embodiments of the present invention are written in a progressive manner, emphasizing the differences between the various implementation schemes, and the similar parts can be referred to each other.

[0049] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for integrally molding the keel beam and bottom of a ground effect vehicle, characterized in that, include: Pre-curing of the ship bottom: The composite material paving material is laid and cured to produce a composite material ship bottom, wherein the inner side of the ship bottom is a continuous curved surface; Composite core fabrication: Based on the design height of the zigzag cross-section of the keel beam of the ground effect vehicle and the design contour of the inner curved surface of the bottom, a composite core is fabricated, wherein the composite core includes full-height conformal foam blocks and conformal carbon plates alternately connected along the length of the keel beam; Combination core positioning: The combination core is positioned conformally on the inner curved surface of the ship bottom; Keel beam composite material layup: Keel beam composite material is continuously laid along the overall contour of the outer perimeter of the composite core and the inner curved surface of the ship bottom. Vacuum bag pressure co-bonding curing: The keel beam composite material layup is cured by vacuum bag pressure co-bonding process, realizing the synchronous co-bonding and curing of the keel beam composite material layup with the ship bottom and the keel beam composite material layup with the composite core, resulting in an integrated load-bearing structure of the keel beam and the ship bottom.

2. The method for integrally forming the keel beam and bottom of a ground effect vehicle according to claim 1, characterized in that, The composite material lining material for the ship bottom is a medium-temperature resin system composite prepreg or a composite woven fabric for dry-wet hand lay-up.

3. The method for integrally molding the keel beam and the bottom of a ground effect vehicle according to claim 1, characterized in that, The full-height conformal foam block is a PMI high-strength foam block, which is formed by mechanical processing.

4. The method for integrally molding the keel beam and the bottom of a ground effect vehicle according to claim 1, characterized in that, The conformal carbon plate is a 4mm-6mm carbon fiber plate, which is formed by mechanical processing.

5. The method for integrally molding the keel beam and the bottom of a ground effect vehicle according to claim 1, characterized in that, The full-height conformal foam blocks and conformal carbon plates are alternately connected along the length of the keel beam by structural adhesive to form a zigzag composite core.

6. The method for integrally molding the keel beam and the bottom of a ground effect vehicle according to claim 1, characterized in that, The composite core is attached to the inner curved surface of the ship's bottom with structural adhesive and then cured.

7. The method for integrally molding the keel beam and the bottom of a ground effect vehicle according to claim 1, characterized in that, The composite material paving material for the keel beam is a medium-temperature resin system composite prepreg or a composite woven fabric laid using a dry-wet hand lay-up method.

8. The method for integrally forming the keel beam and bottom of a ground effect vehicle according to claim 1, characterized in that, The specific steps for vacuum bag pressure bonding and curing are as follows: The bottom of the ship, with the composite core positioned and the keel beam composite material layup applied, is placed on the bottom forming mold; Sealing tape is pasted on the edge of the bottom molding mold. Then, release cloth, perforated release film and breathable felt are laid in sequence. After sealing with vacuum bag film, the vacuum valve inside the bag is evacuated through the vacuum system to form a negative pressure environment of 0.08~0.1MPa. This allows the keel beam composite material layup to be tightly pressed onto the outer periphery of the composite core and the inner curved surface of the bottom under negative pressure. Then, the temperature is raised for curing. The resin glue on the keel beam composite material layup or the resin glue of wet hand layup is used to achieve synchronous co-bonding and curing of the keel beam composite material layup with the bottom and the keel beam composite material layup with the composite core. After curing, the auxiliary materials are removed and the surface is polished and repaired to obtain an integrated load-bearing structure of the keel beam and the bottom of the ship.

9. An integrated load-bearing structure for the keel beam and bottom of a ground effect vehicle, characterized in that: include: The hull (200) and the keel beam (100) integrally formed with the hull (200) are a composite material hull. The keel beam (100) has a cross-section in the shape of a "Z". The keel beam (100) includes a composite core and a keel beam composite material layup structure (130). The outer contour of the composite core fits the inner curved surface of the hull (200). The composite core includes full-height conformal foam blocks (110) and conformal carbon plates (120) that are alternately connected along the length direction of the keel beam (100). The keel beam composite material layup structure (130) is tightly cured on the outer periphery of the composite core and its lower part is tightly cured and connected to the inner curved surface of the hull (200).

10. The integrated load-bearing structure of the keel beam and the bottom of the ground effect vehicle according to claim 9, characterized in that, The keel beam (100) is located at the bottom middle of the fuselage (300) of the ground effect vehicle and extends from the front end of the fuselage (300) to the rear end of the fuselage (300).

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