Preparation method of composite thermal protection structure and composite thermal protection structure

Abstract

The application relates to a preparation method of a composite heat protection structure and the composite heat protection structure, wherein the preparation method of the composite heat protection structure comprises the following steps: respectively arranging composite material panels at the top end and the bottom end of a honeycomb core; arranging aerogel thermal insulation material on the composite material panel at the top end, and wrapping a composite material skin outside the aerogel thermal insulation material; connecting the composite material panel and the honeycomb core and the composite material skin and the composite material panel by using structural glue bonding, so as to obtain the composite heat protection structure. The application can reduce the overall density of the honeycomb sandwich structure and improve the heat insulation performance of the honeycomb sandwich structure.

Description

Technical Field

[0001] This application relates to the field of aerospace manufacturing technology, and in particular to a method for preparing a composite thermal protection structure and the composite thermal protection structure itself. Background Technology

[0002] Brazed honeycomb structures are formed by brazing upper and lower panels and a central honeycomb core, exhibiting high specific strength and specific stiffness. Compared to solid materials of the same volume, metal honeycomb transfers significantly less heat in the same amount of time, thus providing a certain degree of thermal insulation. However, the upper and lower panels and the central honeycomb core are all made of metal, resulting in a high effective density and consequently a heavy overall structure. Furthermore, the honeycomb core itself still exhibits thermal bridging, limiting its thermal insulation performance. To further improve the thermal insulation performance of metal honeycomb structures, smaller cell wall thickness or larger cell size could be chosen, but this would reduce load-bearing capacity. Alternatively, a higher cell height could be selected, but this would increase the structural thickness and occupy more space in the aircraft.

[0003] Therefore, the inventors provide a method for preparing a composite thermal protection structure and the composite thermal protection structure itself. Summary of the Invention

[0004] (1) Technical problems to be solved

[0005] This application provides a method for preparing a composite thermal protection structure and the composite thermal protection structure. The technical problem to be solved is that the current metal honeycomb sandwich structure has a high overall density and limited thermal insulation performance.

[0006] (2) Technical solution

[0007] In a first aspect, this application provides a method for preparing a composite thermal protection structure, comprising:

[0008] Composite material panels are installed at the top and bottom of the honeycomb core;

[0009] An aerogel insulation material is provided on the top composite panel, and a composite skin is wrapped around the aerogel insulation material.

[0010] Structural adhesive is used to connect the composite material panel to the honeycomb core, and the composite material skin to the composite material panel, to obtain a composite thermal protection structure;

[0011] The composite material skin has a flange, and the composite material skin is connected to the composite material panel through the flange;

[0012] The method of using structural adhesive to connect the composite material panel to the honeycomb core, and the composite material skin to the composite material panel, includes:

[0013] The honeycomb sandwich structure consisting of the composite material panel and the honeycomb core is sealed around the perimeter using a vacuum bag, and then the inside is evacuated.

[0014] A bolt fastener pressure plate fixture is used to apply pressure at the connection between the flange and the composite material panel.

[0015] Multiple through holes are made in the composite material skin, and the honeycomb sandwich structure and the aerogel insulation material are placed in an autoclave for bonding.

[0016] After the autoclave treatment is completed, a sealing disc is bonded to the through hole using room temperature curing adhesive. The diameter of the sealing disc is larger than the diameter of the through hole.

[0017] Furthermore, the aerogel insulation material is a multilayer insulation material, with metal reflective foil disposed between adjacent insulation materials.

[0018] Furthermore, the thickness of the metal reflective foil is 0.05mm-0.1mm.

[0019] Furthermore, the thickness of the composite material skin is 0.1mm-0.15mm.

[0020] Furthermore, the composite material panel and the composite material skin are made of epoxy resin carbon fiber composite.

[0021] Furthermore, the metal reflective foil is made of aluminum foil.

[0022] Furthermore, the structural adhesive used to connect the composite material panel and the honeycomb core is J116A, and the structural adhesive used to connect the composite material skin and the composite material panel is J116B.

[0023] Secondly, this application provides a composite thermal protection structure, which is prepared based on the preparation method of the composite thermal protection structure described above.

[0024] (3) Beneficial effects

[0025] The above-mentioned technical solution of this application has the following advantages:

[0026] The method for preparing the composite thermal protection structure and the composite thermal protection structure provided in this application reduce the overall density of the honeycomb sandwich structure by using composite materials to replace the metal panel, and improve the thermal insulation performance of the honeycomb sandwich structure by adding aerogel thermal insulation material to the outside of the metal honeycomb. Attached Figure Description

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

[0028] Figure 1 This is a schematic diagram of a honeycomb sandwich structure;

[0029] Figure 2 This is a schematic diagram of heat transfer in a honeycomb sandwich structure.

[0030] Figure 3 A schematic diagram of the composite thermal protection structure provided in this application;

[0031] Figure 4 This is a schematic diagram of a conventional adhesive-bonded vacuum bag sealing process.

[0032] Figure 5 This is a schematic diagram of a high-temperature bonding scheme provided in this application.

[0033] Reference numerals: 11, First composite material panel; 12, Second composite material panel; 13, Honeycomb core; 21, Aerogel insulation material; 22, Metal reflective foil; 31, Composite material skin; 51, Bolt fastener pressure plate fixture; 100, First vacuum bag; 101, Second vacuum bag; 311, Flanged edge; 321, First through hole; 322, Second through hole; 401, First sealing disc; 402, Second sealing disc. Detailed Implementation

[0034] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of this application with unnecessary detail.

[0035] It should be understood that, when used in this application specification and appended claims, the term "comprising" indicates the presence of the described feature, integral, step, operation, element, and / or component, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof. The terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, in the description of this application specification and appended claims, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0036] References to "one embodiment" or "some embodiments" in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized.

[0037] like Figure 1 As shown, the metal brazed honeycomb structure is formed by brazing upper and lower panels and a middle honeycomb core, and has the characteristics of high specific strength and specific stiffness. Figure 2 As shown, when the surface of the honeycomb skin is heated, the heat transfer mechanism is heat conduction through the honeycomb core cell walls. q sc Heat conduction of internal gases q r Radiative heat exchange with honeycomb cavity q g Compared to solid materials of the same volume, metal honeycomb transfers much less heat in the same amount of time, thus metal honeycomb structures also have a certain degree of thermal insulation performance.

[0038] While metal honeycomb structures offer a combination of advantages in load-bearing and thermal insulation performance, their limitations become apparent as aircraft structures increasingly demand higher weight and thermal insulation specifications. Firstly, the upper and lower panels and the central honeycomb core are all made of metal, resulting in a high overall structural density and consequently, a heavy weight. Secondly, the internal honeycomb core still exhibits thermal bridging effects, limiting its thermal insulation performance. To further improve the thermal insulation of metal honeycomb structures, options include choosing thinner core walls or larger core dimensions, which reduces load-bearing capacity, or choosing higher honeycomb heights, increasing structural thickness and occupying valuable aircraft space.

[0039] To address the shortcomings of current metal honeycomb sandwich structures, such as high overall density and limited thermal insulation performance, this application proposes a method for preparing a composite thermal protection structure and the composite thermal protection structure itself. The main objective is:

[0040] Replacing metal panels with composite materials reduces the overall density of the structure: For metal honeycomb structures, the weight of the panels accounts for more than 70% of the total weight of the honeycomb structure. Replacing metal panels with low-density composite materials can reduce the overall equivalent density of the structure by more than 15%.

[0041] Aerogel insulation material is added to the outside of the metal honeycomb. To avoid problems such as easy detachment of the aerogel insulation material, a composite protective skin is wrapped around the outside of the aerogel.

[0042] The specific embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this application, but are not intended to limit the scope of this application.

[0043] This embodiment provides a method for preparing a composite thermal protection structure, including:

[0044] Composite material panels are installed at the top and bottom of the honeycomb core;

[0045] An aerogel insulation material is provided on the top composite panel, and a composite skin is wrapped around the aerogel insulation material.

[0046] Structural adhesive is used to connect the composite material panel to the honeycomb core, and the composite material skin to the composite material panel, to obtain a composite thermal protection structure;

[0047] The composite material skin has a flange, and the composite material skin is connected to the composite material panel through the flange;

[0048] The method of using structural adhesive to connect the composite material panel to the honeycomb core, and the composite material skin to the composite material panel, includes:

[0049] The honeycomb sandwich structure consisting of the composite material panel and the honeycomb core is sealed around the perimeter using a vacuum bag, and then the inside is evacuated.

[0050] A bolt fastener pressure plate fixture is used to apply pressure at the connection between the flange and the composite material panel.

[0051] Multiple through holes are made in the composite material skin, and the honeycomb sandwich structure and the aerogel insulation material are placed in an autoclave for bonding.

[0052] After the autoclave treatment is completed, a sealing disc is bonded to the through hole using room temperature curing adhesive. The diameter of the sealing disc is larger than the diameter of the through hole.

[0053] In some embodiments, the aerogel insulation material is a multilayer insulation material, with a metal reflective foil disposed between adjacent insulation materials.

[0054] In some embodiments, the thickness of the metal reflective foil is 0.05 mm to 0.1 mm.

[0055] In some embodiments, the thickness of the composite material skin is 0.1 mm to 0.15 mm.

[0056] like Figure 3 As shown, in application, the first composite material panel 11 and the second composite material panel 12 can be used to replace the traditional metal panel, while the honeycomb core 13 remains a metal honeycomb core, thereby reducing the weight of the honeycomb structure. Structural adhesive is used to connect the first composite material panel 11 to the honeycomb core 13, and the second composite material panel 12 to the honeycomb core 13. Aerogel insulation material 21 is placed on the outer surface of the first composite material panel 11. To further improve insulation performance, layered aerogel insulation material is used, and a 0.05mm-0.1mm metal reflective foil 22 is placed between adjacent insulation materials.

[0057] A 0.1mm-0.15mm thick, cured composite material skin 31 is applied to the outer surface of the multilayer thermal insulation material consisting of "aerogel thermal insulation material / metal reflective foil / aerogel thermal insulation material" to solve the problem of easy detachment of the aerogel thermal insulation material and achieve the purpose of encapsulating and protecting the thermal insulation material. The composite material skin 31 has flanges 311, which are connected to the first composite material panel 11 using a structural adhesive film.

[0058] In applications, bonding structural adhesive films requires specific temperature and pressure conditions. A common method is to use vacuum sealing combined with an autoclave for bonding. For example... Figure 4As shown, the conventional bonding method involves completely encasing the product in a first vacuum bag 100. Figure 3 The structure to be bonded, as shown, is then placed in an autoclave for overall gas pressurization. However, for... Figure 3 The composite structure shown has multiple layers of insulation material on one side, consisting of "aerogel insulation material / metal reflective foil / aerogel insulation material". These multiple layers of insulation material have poor load-bearing capacity. Figure 4 The method of using a vacuum bag as shown has the problem of easily collapsing the multi-layer insulation material of "aerogel insulation material / metal reflective foil / aerogel insulation material".

[0059] Therefore, in order to achieve the goals proposed in this application Figure 3 The conventional manufacturing process for the composite thermal protection structure shown is a two-step bonding process: First, a vacuum bag and autoclave method is used to bond the first composite material panel 11, the honeycomb core 13, and the second composite material panel 12 honeycomb sandwich structure. Then, tooling is used to apply local pressure at the connection between the flange 311 of the composite material skin 31 and the first composite material panel 11. The area is then placed in an autoclave or heating chamber for heating to bond the flange 311 to the first composite material panel 11. However, the two-step bonding method requires two high-temperature bonding processes, resulting in a long production cycle and high cost.

[0060] To address the aforementioned problems, this application proposes a method for preparing composite thermal protection structures using a single high-temperature adhesive bonding process, such as... Figure 5 As shown, the main considerations are as follows:

[0061] A small number of first through holes 321 and second through holes 322 with a diameter of 5-10 mm are provided on the composite material skin 31. The purpose is to allow gas to enter the internal cavity covered by the composite material skin 31 during bonding, so as to provide the pressure required for bonding the first composite material panel 11 and the honeycomb core 13.

[0062] A second vacuum bag 101 is used to cover and seal the honeycomb sandwich structure composed of the first composite material panel 11, the honeycomb core 13 and the second composite material panel 12. The second vacuum bag 101 is sealed to the first composite material panel 11 and the second composite material panel 12 with synthetic rubber vacuum sealing tape.

[0063] At the connection between the flange 311 and the first composite material panel 11, a bolt fastener pressure plate fixture 51 is used to apply pressure to ensure the bonding pressure between the flange 311 and the first composite material panel 11.

[0064] The implementation process is as follows:

[0065] A second vacuum bag 101 is used to seal the honeycomb sandwich structure composed of the first composite material panel 11, the honeycomb core 13, and the second composite material panel 12, and then the inside is evacuated.

[0066] At the connection between the flange 311 and the composite material skin 31, a bolt fastener pressure plate fixture 51 is placed and pressure is applied;

[0067] The entire structure is placed in an autoclave, heated to a suitable temperature, and subjected to appropriate gas pressure for overall bonding. During the bonding process, the high-pressure gas in the autoclave enters the cavity of the composite material skin 31 through the first through hole 321 and the second through hole 322, applying the necessary pressure to the bonding interface between the first composite material panel 11, the second composite material panel 12, and the honeycomb core 13, thereby achieving the bonding of the honeycomb sandwich structure composed of the first composite material panel 11, the honeycomb core 13, and the second composite material panel 12. Simultaneously, under the action of the autoclave heating temperature and the pressure of the bolt fastener pressure plate fixture 51, the flange 311 is bonded to the connection with the first composite material panel 11, thus realizing the one-time high-temperature bonding preparation of the composite thermal protection structure.

[0068] After the overall structure is bonded, the first sealing disc 401 and the second sealing disc 402 are bonded to the first through hole 321 and the second through hole 322 of the composite material skin 31 using room temperature curing adhesive. The diameter of the first sealing disc 401 and the second sealing disc 402 is 4-10 mm larger than the diameter of the first through hole 321 and the second through hole 322.

[0069] In some embodiments, the composite panel and the composite skin are made of epoxy resin carbon fiber composite.

[0070] In some embodiments, the metal reflective foil is aluminum foil.

[0071] In some embodiments, the structural adhesive used to connect the composite material panel and the honeycomb core is J116A, and the structural adhesive used to connect the composite material skin and the composite material panel is J116B.

[0072] In application, the following example illustrates a composite thermal protection structure consisting of epoxy resin carbon fiber composite panel / metal honeycomb core / epoxy resin carbon fiber composite panel + multi-layer thermal insulation material of "aerogel thermal insulation material / metal reflective foil / aerogel thermal insulation material" + epoxy resin carbon fiber composite skin covering layer.

[0073] Panel material: 0.8mm thick epoxy resin carbon fiber composite; honeycomb core: TC4 titanium alloy honeycomb core, foil thickness 0.1mm, core cell size 11.2mm, core cell height 5mm; aerogel insulation material is basalt fiber, metal reflective foil is aluminum foil, aerogel insulation material consists of three layers with thicknesses of 2mm, 2mm and 1mm respectively, and the metal reflective foil aluminum foil has a thickness of 50μm; composite material skin covering layer is 0.12mm thick epoxy resin carbon fiber composite; the adhesive film for bonding epoxy resin carbon fiber composite panel / metal honeycomb core / epoxy resin carbon fiber composite panel is J116A, and the adhesive film for bonding epoxy resin carbon fiber composite panel and composite material skin covering layer is J116B.

[0074] Implementation process:

[0075] Using a thermoforming mold, 0.12mm thick epoxy resin carbon fiber composite material is formed into a composite material skin with a 5mm depth, and four 10mm diameter ventilation holes are machined on the upper surface.

[0076] A J116A adhesive film is placed on the surface of the composite material panel and assembled with the metal honeycomb core;

[0077] The method of wrapping around the four sides is adopted. The assembled honeycomb structure is wrapped and sealed around the four sides using a vacuum bag, and then the inside is vacuumed.

[0078] The composite material skin covering layer is placed on the outside of the multi-layer thermal insulation material of "aerogel thermal insulation material / metal reflective foil / aerogel thermal insulation material"; and bolt fastener pressure plate fixtures are installed at the flange and pressure is applied;

[0079] The entire structure was placed in an autoclave, heated to 180°C, at 3 atmospheres, and held for 3 hours.

[0080] After the autoclave treatment is completed, a 15mm diameter, 0.12mm thick sealing disc is bonded to the through hole of the thin-walled coating layer using room temperature curing adhesive.

[0081] The table below shows a comparison of the weight of the composite thermal protection structure prepared by the above method with that of a titanium alloy honeycomb structure of the same size, as well as the thermal insulation performance under a hot surface environment of 200℃ / 60min. The equivalent density of the structure is reduced by 30.6%, and the cold surface temperature is reduced by 34.3% and 42.7% respectively under the conditions of protective device and natural convection.

[0082]

[0083] This embodiment also provides a composite thermal protection structure, which is prepared based on the preparation method of the composite thermal protection structure described above.

[0084] The method for preparing the composite thermal protection structure and the composite thermal protection structure provided in this application address the shortcomings of current metal honeycomb sandwich structures, which have high overall density and limited thermal insulation performance. It proposes a composite thermal protection structure consisting of a composite material panel / metal honeycomb core structure and a multi-layer thermal insulation material of "aerogel thermal insulation material / metal reflective foil / aerogel thermal insulation material". Compared with a metal honeycomb structure of the same height, the equivalent density is reduced by more than 15%, and the thermal insulation performance is improved by more than 30%. For the proposed composite thermal protection structure, methods such as setting ventilation holes in the covering skin and using a combination of vacuum bags and bolt fastener pressure plates are proposed to achieve one-time high-temperature adhesive bonding preparation of the composite thermal protection structure.

[0085] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0086] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for preparing a composite thermal protection structure, characterized in that, include: Composite material panels are installed at the top and bottom of the honeycomb core; An aerogel insulation material is provided on the top composite panel, and a composite skin is wrapped around the aerogel insulation material. Structural adhesive is used to connect the composite material panel to the honeycomb core, and the composite material skin to the composite material panel, to obtain a composite thermal protection structure; The composite material skin has a flange, and the composite material skin is connected to the composite material panel through the flange; The method of using structural adhesive to connect the composite material panel to the honeycomb core, and the composite material skin to the composite material panel, includes: The honeycomb sandwich structure consisting of the composite material panel and the honeycomb core is sealed around the perimeter using a vacuum bag, and then the inside is evacuated. A bolt fastener pressure plate fixture is used to apply pressure at the connection between the flange and the composite material panel. Multiple through holes are made in the composite material skin, and the honeycomb sandwich structure and the aerogel insulation material are placed in an autoclave for bonding. After the autoclave treatment is completed, a sealing disc is bonded to the through hole using room temperature curing adhesive. The diameter of the sealing disc is larger than the diameter of the through hole.

2. The method for preparing the composite thermal protection structure as described in claim 1, characterized in that, The aerogel insulation material is a multi-layer insulation material, with metal reflective foils placed between adjacent insulation materials.

3. The method for preparing the composite thermal protection structure as described in claim 2, characterized in that, The thickness of the metal reflective foil is 0.05mm-0.1mm.

4. The method for preparing the composite thermal protection structure as described in claim 1, characterized in that, The thickness of the composite material skin is 0.1mm-0.15mm.

5. The method for preparing the composite thermal protection structure as described in claim 1, characterized in that, The composite panel and the composite skin are made of epoxy resin carbon fiber composite.

6. The method for preparing the composite thermal protection structure as described in claim 2, characterized in that, The metal reflective foil is made of aluminum foil.

7. The method for preparing the composite thermal protection structure as described in claim 1, characterized in that, The structural adhesive used to connect the composite material panel to the honeycomb core is J116A, and the structural adhesive used to connect the composite material skin to the composite material panel is J116B.

8. A composite thermal protection structure, characterized in that, The composite thermal protection structure is prepared based on the preparation method of the composite thermal protection structure as described in any one of claims 1 to 7.

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