Ablation-bearing integrated shell component and forming method thereof

Abstract

The invention discloses an ablation-bearing integrated shell component and a forming method thereof, and belongs to the technical field of composite component design and forming. The shell component comprises a bearing layer, a matching layer and an ablation layer, the bearing layer is located on the innermost layer, the ablation layer is located on the outermost layer, the matching layer is located between the bearing layer and the ablation layer, and the three-layer structure adopts a resin system with approximate curing temperature. The forming method comprises the steps of laying of the bearing layer, laying of the matching layer, laying of the ablation layer and primary curing. The interface reliability problem caused by mismatching of linear expansion coefficients of the ablation layer and the bearing layer is solved through the matching layer, the cost is reduced and the period is shortened by adopting the one-time curing process, and the bonding force and the forming quality of the structural interface are remarkably improved.

Description

Technical Field

[0001] The invention relates to an ablation-load-bearing integrated shell component and a molding method thereof, belonging to the technical field of composite material component design and molding. Background Art

[0002] As the flight speed and range of aircraft continue to increase, the requirements for lightweight and temperature resistance / heat protection are getting higher and higher. The existing metal + heat protection structure solution can no longer meet the development of new aircraft due to problems such as long production cycle and complicated process flow. Composite shells are gaining more and more attention in the aerospace field due to their high specific stiffness and specific strength, short production cycle, and good matching of load-bearing and ablation structures.

[0003] At present, the common pure composite ablative-load-bearing components adopt step-by-step molding or independent molding and then assembly schemes for the load-bearing structure and the ablative structure, and the two structures are connected by adhesive films or adhesives. Although this scheme is highly mature, it also has high requirements for molds, and the cycle, equipment and labor costs required for both step-by-step molding and independent molding are high, which is increasingly unable to meet the requirements of high-speed aircraft development in terms of cost and cycle. Summary of the invention

[0004] The purpose of the present invention is to propose an ablation-load-bearing integrated shell structure and a forming method thereof. This method can realize the one-time, integral forming of the ablation structure and the load-bearing structure of the shell-type component through a set of molds, which greatly saves costs and cycles, and the interface reliability of the ablation and load-bearing structures can also be effectively guaranteed.

[0005] The technical solution adopted by the present invention to achieve the above-mentioned purpose is as follows:

[0006] An ablation-load-bearing integrated shell component comprises a three-layer structure of a load-bearing layer, a matching layer and an ablation layer, wherein the load-bearing layer is located at the innermost layer, the ablation layer is located at the outermost layer, and the matching layer is located between the load-bearing layer and the ablation layer. The three-layer structure adopts a resin system with similar curing temperatures, and the close curing temperature means that the curing temperature difference does not exceed a temperature threshold; wherein the load-bearing layer is a carbon fiber reinforced resin-based composite material, the ablation layer is a fiber reinforced resin-based ablation composite material, and the matching layer is a linear expansion matching layer with a linear expansion coefficient between the load-bearing layer and the ablation layer.

[0007] Furthermore, the resin used in the bearing layer is medium-temperature or high-temperature epoxy resin, or bismaleimide resin.

[0008] Furthermore, the reinforcement used in the ablation layer is a plain fabric composed of quartz fiber, high silica fiber or glass fiber, or a mixed fabric of quartz fiber, high silica fiber or glass fiber and aramid fiber or phenolic fiber, and the resin system used is phenolic resin or benzoxazine resin.

[0009] Furthermore, the curing temperatures being close means that the curing temperatures differ by no more than 20°C.

[0010] Furthermore, the linear expansion coefficient of the carbon fiber reinforced high temperature epoxy resin used in the bearing layer is 2*10 -6 The linear expansion coefficient of the quartz fiber reinforced phenolic resin used in the ablation layer is 10-12*10 -6 , the linear expansion coefficient of the matching layer is 5-8*10 -6 .

[0011] Furthermore, the matching layer uses the resin system of the ablative layer or the bearing layer, and uses a mixed fabric of the reinforcing fibers used in the ablative layer and the bearing layer as the reinforcement. For example, the bearing layer is a carbon fiber reinforced high temperature epoxy system, and its linear expansion coefficient is 2*10 -6 The ablation layer is a quartz fiber reinforced phenolic resin system with a linear expansion coefficient of 10-12*10 -6 The matching layer is made of quartz fiber and carbon fiber alternately woven mixed fabric reinforced phenolic resin material, and its linear expansion coefficient is generally 5-8*10 -6 Within the range, it can meet the needs of line increase matching.

[0012] Furthermore, the matching layer uses the resin system of the ablative layer or the bearing layer, and uses the reinforcing fabric that is not used in the ablative layer and the bearing layer. The reinforcing fabric is a flat woven fabric or a three-dimensional woven fabric. For example, if the bearing layer is a carbon fiber reinforced high-temperature epoxy system and the ablative layer is a quartz fiber reinforced phenolic resin system, the matching layer can use aramid fabric. The linear expansion coefficient of some specifications of aramid fabric reinforced phenolic resin materials is 5-8*10 -6 Within the range, it can also meet the needs of line expansion matching. Some three-dimensional woven fabrics can achieve the same effect by designing the weaving structure and density.

[0013] A method for forming an ablation-load-bearing integrated shell component comprises the following steps:

[0014] 1) Laying of the ribs of the bearing layer: Lay the bearing layer material in the rib area of ​​the male mold and iron it flat, and pre-set the laying angle of the ribs;

[0015] 2) Laying the load-bearing layer skin: Laying the load-bearing layer material layer by layer on the male mold;

[0016] 3) Matching layer laying: Lay the matching layer material layer by layer on the outer side of the bearing layer on the male mold;

[0017] 4) Laminating the ablative layer: Laying the ablative layer material layer by layer to the outside of the matching layer on the male mold;

[0018] 5) Mold closing: close the female mold with the male mold, and install the upper and lower cover plates;

[0019] 5) Overall curing: Put the mold after mold closing into an oven and use the hot expansion molding method, autoclave method or molding method for overall curing. The curing system adopts step-by-step temperature curing;

[0020] 6) Demolding: After curing is completed, the mold is naturally cooled and demolded to obtain an ablation-load-bearing integrated shell component.

[0021] Furthermore, in step 1), if the reinforcement bar is a longitudinal reinforcement, the laying angle is 0° (ie, in the shell height direction); if it is a circular reinforcement, the laying angle is 90° (ie, perpendicular to the shell height direction).

[0022] Furthermore, in step 2), the load-bearing layer skin layer is quasi-isotropic, that is, the fiber extension is [45° / 0° / -45° / 90°] s Layers can be laid in a specific order; layers of special specifications and angles can also be laid according to the design of the shell structure.

[0023] Furthermore, in step 3), the thickness of the matching layer does not exceed one quarter of the total thickness of the shell, and the thickness value does not exceed 1 mm. The total thickness of the shell refers to the thickness of the three-layer structure excluding the ribs.

[0024] Furthermore, in step 4), the ablation layer does not exceed two-thirds of the total thickness of the shell, and the thickness value does not exceed 6 mm. The total thickness of the shell refers to the thickness of the three-layer structure excluding the ribs.

[0025] Furthermore, in step 5), for the quasi-rotating shell with complex rib structure of large thickness (total thickness exceeds 8mm), hot expansion forming method is adopted for curing; for the simple rib structure of medium and low thickness (total thickness is less than 8mm), hot autoclave method is adopted for curing; for the shell structure with single-side open large thickness (total thickness exceeds 8mm), molding method is adopted for curing.

[0026] Furthermore, in step 5), the curing system of the hot expansion molding method, the autoclave method or the compression molding method is set according to the higher curing temperature in the resin system of the ablation layer or the bearing layer; and the curing pressure is not less than 0.6 MPa.

[0027] Beneficial effects achieved by the present invention:

[0028] 1. Significant reduction in molding cycle and cost: The present invention adopts one-time curing molding technology to avoid the two curing processes required for the traditional method of laying and curing the bearing layer and the ablation layer respectively, which greatly shortens the manufacturing cycle and reduces labor costs.

[0029] 2. Enhanced interface reliability: The present invention adds a matching layer between the ablation layer and the bearing layer. The design of the matching layer allows the linear expansion coefficient of the material to gradually decrease from the outside to the inside, thereby effectively solving the interface reliability problem caused by the mismatch of the linear expansion coefficient in the conventional structure.

[0030] 3. Material system optimization: The bearing layer, matching layer and ablation layer of the present invention all adopt resin systems with similar curing temperatures, which ensures that the curing process between the layers is coordinated and consistent, thereby further improving the overall structural strength and reliability of the finished product.

[0031] 4. Adapt to the molding requirements of complex structures: For shell structures of different thicknesses and complexities, the present invention provides a variety of molding processes, such as hot expansion molding, autoclave method and molding method, which can flexibly cope with shell structures of different shapes and thicknesses.

[0032] 5. Improve the interface bonding strength: The present invention ensures the strong interface bonding strength between the ablation layer, the matching layer and the bearing layer by setting the curing pressure not less than 0.6 MPa, thereby ensuring the molding quality and performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic structural diagram of the ablation-load-bearing integrated shell component in the embodiment.

[0034] Figure 2 It is a diagram of the forming process of the ablation-load-bearing integrated shell component in the embodiment. DETAILED DESCRIPTION

[0035] In order to make the various technical features and advantages or technical effects in the above technical solutions of the present invention more obvious and easy to understand, they are described in detail below with reference to the accompanying drawings.

[0036] The embodiment of the present invention specifically discloses an ablation-load-bearing integrated shell component, the structure of which is as follows Figure 1 As shown, a three-layer structure including a bearing layer, a matching layer and an ablation layer is provided, wherein the bearing layer is located at the innermost layer, the ablation layer is located at the outermost layer, and the matching layer is located between the bearing layer and the ablation layer. The three-layer structure adopts a resin system with similar curing temperatures, and the similar curing temperatures refer to that the difference in curing temperature does not exceed a temperature threshold; wherein the bearing layer is a carbon fiber reinforced resin-based composite material, the ablation layer is a fiber reinforced resin-based ablation composite material, and the matching layer is a linear expansion matching layer with a linear expansion coefficient between the bearing layer and the ablation layer.

[0037] The embodiment of the present invention also discloses a molding method of an ablation-load-bearing integrated shell component. The molding process is as follows: Figure 2 As shown, the specific steps include:

[0038] The first step is to lay the ribs of the load-bearing layer: first prepare the hot expansion forming male mold, mix the E640 silicone rubber AB components in a ratio of 1:1, stir for 10 minutes, and pour them into the rubber mold. After 24 hours, the curing is completed and the male mold is taken out. Then, T700 / 8522 ​​high-temperature epoxy prepreg is laid along the annular ribs and longitudinal ribs into the preset rib concave area of ​​the hot expansion forming male mold until it is flush with the surrounding rubber mold.

[0039] Step 2: Lay out the load-bearing skin layer: Lay out the T700 / 8522 ​​high temperature epoxy prepreg according to [45° / 0° / -45° / 90° / 90° / -45° / 0° / 45°] s The skin is laid in the ply direction, with a total of 3 layer groups / 3mm thickness.

[0040] The third step is matching layer laying: T700 / 8522 ​​high temperature epoxy plain fabric prepreg and high silica / benzoxazine prepreg are alternately laid on the outside of the bearing layer laid in the second step, 2 layers each, with a total thickness of 0.9mm.

[0041] Step 4: Laying of ablative layer: Lay the quartz / benzoxazine prepreg layer by layer on the outside of the matching layer laid in the third step, with a total of 15 layers / 3 mm thick.

[0042] Step 5: Mold closing: Complete the installation of the female mold and the upper and lower cover area molds, and lock them with screws.

[0043] Step 6, overall curing: put the mold into a large track oven, and check that the oven and temperature probe are working properly. Rapidly heat the oven from room temperature to 130℃±5℃ → keep warm until the mold temperature reaches 120℃ → heat the oven to 180℃±5℃ → keep warm until the mold temperature reaches 160℃ → heat the oven to 210℃±5℃ → keep warm until the mold temperature reaches 180℃ → cool the oven to 190℃±5℃ → keep warm for 4h, shut down and dissipate heat.

[0044] Step 7: Demolding: Allow the mold to cool naturally to below 50°C for demolding to obtain an ablation-load-bearing integrated shell component.

[0045] The performance of the ablation-load-bearing integrated shell component is tested:

[0046] 1. Internal quality inspection: Refer to GB / T 38537-2020 to conduct ultrasonic C-scan inspection on the cabin section. The maximum defect Z value shall not exceed 50mm, and the total defect area shall not exceed 0.1% of the total area of ​​the outer surface of the shell.

[0047] 2. Contour detection: The area where the shell contour is within the range of ±1mm exceeds 95% of the total shell area.

[0048] 3. Combined force and heat test: The outer surface of the shell is heated to 600℃ by a quartz lamp. After keeping warm for 1 minute, a stress of 10t is applied to the shell in the axial direction. The bearing layer of the shell is not damaged.

[0049] Although the present invention has been disclosed as above by way of embodiments, it is not intended to limit the present invention. Appropriate modifications or equivalent substitutions of the technical solutions of the present invention made by ordinary technicians in the field should all be included in the protection scope of the present invention. The protection scope of the present invention shall be based on what is defined in the claims.

Claims

1. An ablation-load-bearing integrated shell component, characterized in that: The invention comprises a three-layer structure of a bearing layer, a matching layer and an ablation layer, wherein the bearing layer is located at the innermost layer, the ablation layer is located at the outermost layer, and the matching layer is located between the bearing layer and the ablation layer. The three-layer structure adopts a resin system with similar curing temperatures, and the similar curing temperatures refer to that the difference in curing temperature does not exceed a temperature threshold. The bearing layer is a carbon fiber reinforced resin-based composite material, the ablation layer is a fiber reinforced resin-based ablation composite material, and the matching layer is a linear expansion matching layer with a linear expansion coefficient between the bearing layer and the ablation layer.

2. The ablation-load bearing integrated shell component according to claim 1, characterized in that: The resin used in the bearing layer is medium-temperature or high-temperature epoxy resin, or bismaleimide resin; the reinforcement used in the ablation layer is a plain fabric composed of quartz fiber, high-silica fiber or glass fiber, or a mixed fabric of quartz fiber, high-silica fiber or glass fiber and aramid fiber or phenolic fiber, and the resin system used is phenolic resin or benzoxazine resin; the matching layer uses the resin system of the ablation layer or the bearing layer, and uses a mixed fabric of the reinforcing fibers used in the ablation layer and the bearing layer as the reinforcement, or uses a reinforcing fabric not used in the ablation layer and the bearing layer, and the reinforcing fabric is a flat woven fabric or a three-dimensional woven fabric.

3. The ablation-load bearing integrated shell component according to claim 1, characterized in that: The curing temperatures are close to each other, which means that the difference between the curing temperatures does not exceed 20°C.

4. The ablation-load bearing integrated shell component according to claim 1, characterized in that: The linear expansion coefficient of the carbon fiber reinforced high temperature epoxy resin used in the bearing layer is 2*10 -6 The linear expansion coefficient of the quartz fiber reinforced phenolic resin used in the ablation layer is 10-12*10 -6 , the linear expansion coefficient of the matching layer is 5-8*10 -6 .

5. A method for forming an ablation-load-bearing integrated shell component according to any one of claims 1 to 4, characterized in that: The following steps are involved: 1) Laying of the ribs of the bearing layer: Lay the bearing layer material in the rib area of ​​the male mold and iron it flat, and pre-set the laying angle of the ribs; 2) Laying the load-bearing layer skin: Laying the load-bearing layer material layer by layer on the male mold; 3) Matching layer laying: Lay the matching layer material layer by layer on the outer side of the bearing layer on the male mold; 4) Laminating the ablative layer: Laying the ablative layer material layer by layer to the outside of the matching layer on the male mold; 5) Mold closing: close the female mold with the male mold, and install the upper and lower cover plates; 5) Overall curing: Put the mold after mold closing into an oven and use the hot expansion molding method, autoclave method or molding method for overall curing. The curing system adopts step-by-step temperature curing; 6) Demolding: After curing is completed, the mold is naturally cooled and demolded to obtain an ablation-load-bearing integrated shell component.

6. The molding method according to claim 5, characterized in that: Step 1) If the reinforcement is a longitudinal reinforcement, the laying angle is in the shell height direction; if it is a circular reinforcement, the laying angle is perpendicular to the shell height direction.

7. The molding method according to claim 5, characterized in that: Step 2) The load-bearing layer skin is quasi-isotropic, that is, the fiber extension is [45° / 0° / -45° / 90°] s Lay the layers in the order of.

8. The molding method according to claim 5, characterized in that: In step 3), the thickness of the matching layer does not exceed one quarter of the total thickness of the shell, and the thickness value does not exceed 1 mm; in step 4), the thickness of the ablation layer does not exceed two thirds of the total thickness of the shell, and the thickness value does not exceed 6 mm. The total thickness of the shell refers to the thickness of the three-layer structure excluding the ribs.

9. The molding method according to claim 5, characterized in that: In step 5), for the quasi-rotating shell with rib structure with a total thickness exceeding 8 mm, the thermal expansion forming method is used for curing; for the rib structure with a total thickness less than 8 mm, the autoclave method is used for curing; for the shell structure with a total thickness exceeding 8 mm with a single-sided opening, the molding method is used for curing.

10. The molding method according to claim 5, characterized in that: In step 5), the curing system of the hot expansion molding method, the autoclave method or the compression molding method is set according to the higher curing temperature in the resin system of the ablation layer or the bearing layer; the curing pressure is not less than 0.6 MPa.

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