Large-taper-angle composite material skin stringer multifunctional cabin structure

Abstract

The invention discloses a large-taper-angle composite material skin stringer multifunctional cabin structure which comprises stringers, a skin lower end frame integrated structure, a box type instrument support and a metal upper end frame. The metal upper end frame and the skin lower end frame are integrally connected to form a main body of the multifunctional cabin structure. The skin lower end frame integrated structure is made of composite materials, and the wall thickness is gradually increased from top to bottom. The box type instrument support is arranged on the outer wall of the skin lower end frame integrated structure and used for installing the instrument support. The stringers are arranged on the inner wall of the skin lower end frame integrated structure, and the axial bearing capacity of the skin lower end frame integrated structure is improved. According to the invention, the functions of the instrument cabin and the transition bracket are integrated into one cabin, so that the strength problem of a large cone angle structure and the lightweight requirement are solved, and reliable connection of instrument installation and the satellite bracket is realized.

Description

Technical Field

[0001] This invention relates to a multifunctional cabin structure with a large cone angle composite material skin stringer, belonging to the field of rocket body design technology. Background Technology

[0002] Currently, most domestic and international launch vehicles use a separate module to install instruments. In order to meet the needs of satellite launches with multiple interfaces, a transition bracket module is generally used to achieve the transition matching of interfaces.

[0003] To improve the rocket's carrying capacity, the final stage of the rocket needs to minimize the number of single-function modules. By using a single module to perform multiple functions, the number of modules, weight, and length of the rocket can be reduced, thereby further reducing the structural weight. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a multi-functional cabin structure with a large cone angle composite material skin stringer, which integrates the functions of the instrument cabin and the transition support into one cabin, solves the strength problem and lightweight requirements of the large cone angle structure, and realizes a reliable connection between the instrument installation and the satellite support.

[0005] The technical solution of this invention is:

[0006] A multi-functional cabin structure with a large cone angle composite material skin stringer includes an integrated structure of stringers, a lower skin frame, a box-type instrument bracket, and a metal upper frame.

[0007] The metal upper frame and the skin lower frame are connected in an integrated structure to form the main body of the multi-functional cabin structure.

[0008] The integrated structure of the lower end frame of the skin has a gradually changing thickness design and is made of composite materials;

[0009] The box-type instrument bracket is mounted on the outer wall of the integrated structure of the lower end frame of the skin and is used to install the instrument bracket.

[0010] Multiple stringers are installed on the inner wall of the integrated lower end frame structure of the skin to improve the axial bearing capacity of the integrated lower end frame structure of the skin.

[0011] Furthermore, the stringer section is an I-shaped structure, including an upper edge plate, a lower edge plate, and a web connecting the upper and lower edge plates. It employs a hot-melt prepreg layup / autoclave curing process, with the web, upper edge plate, and lower edge plate having a layup of [C / 0 / +30 / 0 / -30 / 0 / 90 / +30 / 90 / -30]. S .

[0012] Furthermore, the stringers are reinforced at the upper and lower edge plates, and the local connection strength of the stringers is improved by adding ±45° ply at the front and rear ends.

[0013] Furthermore, the multi-functional cabin structure is also equipped with a foam-filled intermediate frame, which is installed on the inner wall of the integrated structure of the lower end frame of the skin, facing upwards; the foam-filled intermediate frame is filled with PMI foam and has I-shaped stringer clearance gaps.

[0014] Furthermore, the foam-filled intermediate frame adopts a Z-shaped cross-section layer design.

[0015] Furthermore, the integrated structure of the lower frame of the skin is formed by autoclaving after carbon fiber layup. At a set height from the lower end face, a transition zone with a triangular cross section is used to achieve a gradual transition from the skin to the lower frame. The transition zone is covered by a staggered layering method.

[0016] Furthermore, the skin adopts a 9-layer ply design, while the lower frame mating surface adopts a 46-layer ply design; the top and bottom three layers of the skin surface are continuously plyed with the lower frame, and the middle three layers are plyed within the lower frame. The transition zone is filled with unidirectional strips. The ply sequence is as follows:

[0017] Furthermore, a T-shaped bushing made of titanium alloy is provided, and a pre-drilled mating hole is made at the lower end frame of the integrated skin lower end frame structure. The T-shaped bushing is embedded in the mating hole and connected by adhesive bonding.

[0018] Furthermore, cable entry and exit holes are provided on the integrated structure of the lower end frame of the skin. To reduce stress concentration at the cable entry and exit holes, local ply reinforcement is used around the cable entry and exit holes.

[0019] Furthermore, the box-type instrument stand is formed using RTM technology and features internal reinforcing ribs.

[0020] The advantages of this invention compared to the prior art are:

[0021] (1) This invention combines instrument installation function and large cone angle transition function. It achieves the functions of two sections of a traditional rocket through one section. The reduction of sections makes the rocket body structure more compact, shortens the overall length of the rocket, and further reduces the weight of the rocket's final stage.

[0022] (2) Based on composite molding technology, this invention designs a high load-bearing I-beam truss, a lightweight integrated structure of the lower skin frame, a high-rigidity foam-filled middle frame and a box-type instrument bracket, which greatly reduces the structural weight and improves the structural carrying capacity.

[0023] (3) In order to improve the axial bearing capacity of the structure, the present invention determines the I-shaped cross-section composite truss through simulation optimization to achieve the matching of overall bearing capacity and local bearing capacity.

[0024] (4) To reduce the structural weight, the present invention adopts an integral ply of the lower end frame of the skin, wherein the skin cone angle is about 42°. After hot-melt prepreg is laid through a male mold tooling, it is cured in a hot autoclave. The stress concentration caused by the sudden change in stiffness is reduced by the gradual ply design. The outer surface of the skin is equipped with an instrument bracket to meet the equipment installation requirements.

[0025] (5) In order to solve the problem of weak axial tensile bearing capacity of the butt joint hole of the composite end frame, the present invention innovatively adopts a T-type bushing design to reduce the impact of local extrusion and delamination of the end frame through the T-type bushing. Attached Figure Description

[0026] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0027] Figure 1 This is a schematic diagram of the multi-functional cabin structure according to an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the external shape of the I-shaped stringer according to an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the plywood cross-section of the I-shaped stringers according to an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of the skin shape in an embodiment of the present invention;

[0031] Figure 5 This is a schematic diagram of the lower frame ply transition and T-shaped bushing in an embodiment of the present invention;

[0032] Figure 6 This is a schematic diagram of the layered reinforcement at the skin opening in an embodiment of the present invention;

[0033] Figure 7 This is a schematic diagram of the interlocking ring frame in an embodiment of the present invention;

[0034] Figure 8 This is a schematic cross-sectional view of a box-type instrument support according to an embodiment of the present invention. Detailed Implementation

[0035] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0036] Based on the space and weight constraints of rocket final stages, this invention proposes a multi-functional cabin structure with a large-cone-angle composite material skin stringer, particularly suitable for designs with large cone angles of 40° to 45°. This structure employs I-shaped composite stringers, an integrated design of variable-thickness skin end frames, a foam-filled composite intermediate frame structure, and T-shaped bushings for the end frames. This meets the requirements of lightweight construction, high rigidity, and instrument and equipment installation, while also enabling a reliable connection between the rocket's final stage and the satellite support via a large-cone-angle transition.

[0037] The multi-functional cabin structure is as follows Figure 1 As shown, it includes an I-beam truss 1, an integrated lower skin frame structure 2, a foam-filled middle frame 3, a box-type instrument bracket 4, a metal upper frame 5, and a T-shaped bushing 6.

[0038] To improve the axial load-bearing capacity of the structure, simulation optimization was used to achieve a match between overall load-bearing capacity and local buckling. I-shaped cross-section composite stringers were determined, with I-shaped stringer 1 primarily serving the axial load-bearing function. Figure 2 As shown. To ensure molding quality, the I-beam stringer 1 adopts a hot-melt prepreg layup / autoclave curing process, with a curing temperature of 130℃ and a holding time of 4 hours. The layup includes two symmetrical C-shaped layups, as shown. Figure 3 As shown. Based on this, continuous composite materials are used to reinforce the upper edge plate 9 and lower edge plate 10. The local connection strength of the stringers is improved by adding ±45° ply at the front and rear ends. The ply of the web plate 8 and the upper edge plate 9 and lower edge plate 10 is [C / 0 / +30 / 0 / -30 / 0 / 90 / +30 / 90 / -30]. S .

[0039] To reduce structural weight, an integrated lower skin frame is used, forming an integrated lower skin frame structure 2. This integrated lower skin frame structure 2 primarily serves to provide structural support and lower-end connection, and also provides a foundation for the installation of instruments and equipment, such as... Figure 4 As shown, the lower frame of the skin is an integrated structure with a 42° cone angle. It is formed by hot-melt prepreg layup using a male mold and then cured in an autoclave. Most areas of the skin employ a 1.8mm, 9-layer layup design, while the lower frame mating surface uses a 6.9mm, 46-layer layup design. The number of layup layers was determined through finite element simulation to ensure that the skin will not experience instability or large strain.

[0040] To mitigate stress concentration, axial loads were applied to the local structures of the lower frame of the skin at multiple transition positions using finite element simulation. Based on the stress distribution, it was ultimately determined that a triangular transition zone at a distance of 120mm from the lower end face would facilitate a gradual transition from the skin to the lower frame. This transition zone employed a staggered layering technique, specifically using a serrated layering pattern. The staggered movement of each serrated step was required to be uniform and less than 2mm. This gradual layering design reduced stress concentration caused by abrupt changes in stiffness. Figure 5 As shown, the outer surface of the skin is fitted with instrument brackets to meet equipment installation requirements. To ensure continuous plying, the skin is laid in groups of three layers. The top and bottom three layers are continuously laid with the lower frame, while the middle three layers are laid within the lower frame. The remaining plying in the transition area is filled with unidirectional tape. The plying sequence is as follows: Pre-drilled butt holes are located at the lower end frame. To improve the strength of these holes and reduce the impact of localized compression and delamination, titanium alloy T-shaped bushings 6 are embedded within them and bonded together with adhesive. The use of titanium alloy aims to reduce the potential difference between the bushing and the carbon fiber, thereby minimizing potential corrosion. Furthermore, the integrated lower end frame structure 2 of the skin has cable entry / exit holes 7. To reduce stress concentration at these holes, the area around them is treated with... Figure 6 The localized ply reinforcement shown uses staggered plies of 0° and ±45°.

[0041] To improve the axial load-bearing capacity of the I-beam truss 1 and the radial stiffness of the compartment, a foam-filled intermediate frame 3 is designed, such as... Figure 7 As shown, the foam-filled intermediate frame 3 adopts a Z-shaped cross-section ply design. The Z-shaped cross-section has the advantages of large moment of inertia and large bending stiffness. The intermediate frame has stringer clearance gaps. In order to improve the cross-sectional stiffness of the intermediate frame, the Z-shaped section is filled with PMI foam.

[0042] The box-type instrument holder 4 is positioned on the outer side of the skin. The box-type instrument holder 4 is formed using RTM technology. To improve the rigidity of the instrument holder, the holder is box-shaped, such as... Figure 8 As shown, the internal design incorporates reinforcing ribs, and the four sides of the box are connected to the skin 2 via bolts or rivets. The box-type instrument bracket provides an interface for instrument installation via internal riveted support plates and nuts.

[0043] The metal upper frame 5 serves as the upper docking point. The stringers 1, skin 2, intermediate frame 3, instrument bracket 4, and upper frame 5 are connected by riveting or bolting to form an integral shell section. The T-shaped bushing 6 is embedded in the pre-drilled hole at the lower end of the skin 2 and is connected by adhesive bonding.

[0044] Based on the skin, each component is assembled using specialized tooling to form a multi-functional cabin structure with composite material skin and stringers. This structure meets the requirements of lightweight, high rigidity, and instrument and equipment installation, and can also achieve a reliable connection between the rocket's final stage and the satellite support through a large cone angle transition.

[0045] The embodiments described above are merely preferred embodiments of the present invention. Ordinary variations and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-functional cabin structure with a large cone-angle composite material skin stringer, characterized in that, This includes the stringers, the integrated structure of the lower skin frame, the box-type instrument bracket, and the metal upper frame; The metal upper frame and the skin lower frame are connected in an integrated structure to form the main body of the multi-functional cabin structure. The integrated structure of the lower end frame of the skin has a gradually changing thickness design and is made of composite materials; The box-type instrument bracket is mounted on the outer wall of the integrated structure of the lower end frame of the skin and is used to install the instrument bracket. Multiple stringers are installed on the inner wall of the integrated lower end frame structure of the skin to improve the axial bearing capacity of the integrated lower end frame structure of the skin.

2. The multi-functional cabin structure with large cone-angle composite material skin stringers according to claim 1, characterized in that, The stringer section is an I-shaped structure, including an upper edge plate, a lower edge plate, and a web connecting the upper and lower edge plates. It employs a hot-melt prepreg layup / autoclave curing process, with the web, upper edge plate, and lower edge plate having a layup of [C / 0 / +30 / 0 / -30 / 0 / 90 / +30 / 90 / -30]. S .

3. The multi-functional cabin structure with large cone-angle composite material skin stringers according to claim 2, characterized in that, The stringers are reinforced at the upper and lower edge plates, and the local connection strength of the stringers is improved by adding ±45° ply at the front and rear ends.

4. The multi-functional cabin structure with large cone-angle composite material skin stringers according to claim 1, characterized in that, The multi-functional cabin structure also features a foam-filled intermediate frame, installed on the inner wall of the integrated structure of the lower end frame of the skin, facing upwards; the foam-filled intermediate frame is filled with PMI foam and has I-shaped strut clearance gaps.

5. The multi-functional cabin structure with large cone-angle composite material skin stringers according to claim 4, characterized in that, The foam-filled middle frame adopts a Z-shaped cross-section layer design.

6. The multi-functional cabin structure with large cone-angle composite material skin stringers according to claim 1, characterized in that, The integrated structure of the lower frame of the skin is formed by autoclaving after carbon fiber lay-up. At a set height from the lower end face, a transition zone with a triangular cross section is used to achieve a gradual transition from the skin to the lower frame. The transition zone is covered by a staggered layering method.

7. The multi-functional cabin structure with large cone-angle composite material skin stringers according to claim 6, characterized in that, The skin uses a 9-layer ply design, while the lower frame mating surface uses a 46-layer ply design. The skin surface has three layers continuously laid on the top and bottom edges with the lower frame, and three layers in the middle are sandwiched within the lower frame. The transition zone is filled with unidirectional tape. The ply sequence is as follows:

8. The multi-functional cabin structure with large cone-angle composite material skin stringers according to claim 1, characterized in that, It also features a T-shaped bushing made of titanium alloy, and pre-drilled docking holes at the lower end frame of the integrated skin structure. The T-shaped bushing is embedded in the docking hole and connected by adhesive bonding.

9. The multi-functional cabin structure with large cone-angle composite material skin stringers according to claim 1, characterized in that, Cable entry and exit holes are provided on the integrated structure of the lower end frame of the skin. To reduce stress concentration at the cable entry and exit holes, local ply reinforcement is used around the cable entry and exit holes.

10. A multi-functional cabin structure with a large cone angle composite material skin stringer according to claim 1, characterized in that, The box-type instrument stand is formed using RTM technology and features internal reinforcing ribs.

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