A j-type composite structure co-curing molding method

Abstract

This application belongs to the field of aerospace composite material manufacturing technology, specifically disclosing a co-curing molding method for J-type composite material structures. The method includes: measuring the thickness difference of the prepreg before and after curing and using it as a reference interference; constructing a dual-mold molding system, used for pre-compaction and co-curing respectively; performing offline pre-compaction treatment on the C-type part; and assembling the pre-compacted C-type part with the Z-type part and the flat plate part without interference, followed by co-curing. This application, through offline pre-compaction compensation technology, can eliminate assembly interference and joint surface defects without modifying the standard mold, thereby improving the molding quality and process adaptability of J-type composite material components.

Description

Technical Field

[0001] This application belongs to the field of aerospace composite material manufacturing technology, specifically relating to a co-curing molding method for J-type composite material structures. Background Technology

[0002] In the manufacturing of aerospace composite structures, J-shaped stringers are typically assembled and co-cured from C-shaped parts, Z-shaped parts, core material, and flat panels. Traditional molds generally follow the "net dimension design principle," meaning the profile is designed based on the net thickness T2 after curing. However, in the uncured state, the prepreg contains air and volatiles between layers, resulting in a thickness T1 that is typically 10% to 15% thicker than T2. ​​This causes the outer contour of the T1-thick C-shaped part to exceed the design boundary when laid on the mold designed according to T2. This creates rigid interference when assembling with the Z-shaped part mold, acting like a wedge that pushes or lifts the Z-shaped part mold, preventing the lower edge of the Z-shaped part from falling into place. It also results in significant assembly gaps between the Z-shaped part and the flat panel, as well as web misalignment. Furthermore, these gaps can easily form resin-rich areas or pores after curing, severely affecting interlaminar shear strength and dimensional accuracy.

[0003] Existing technologies often use forced mold closing or post-molding to solve the above problems, but this can lead to fiber buckling or increase non-structural weight. Therefore, there is an urgent need for an innovative molding method that can effectively solve the interference of prepreg thickness difference. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this application is to provide a co-curing molding method for J-type composite material structures. This application aims to eliminate assembly interference and joint surface defects without modifying standard molds by using offline pre-compaction compensation technology, thereby improving the molding quality and process adaptability of J-type composite material components.

[0005] To achieve the above objectives, this application provides the following technical solution: A method for co-curing and molding a J-type composite material structure, the method comprising: measuring the thickness difference of the prepreg before and after curing and using it as a reference interference amount; constructing a dual-mold molding system for pre-compaction and co-curing respectively; performing offline pre-compaction treatment on the C-type part; assembling the pre-compacted C-type part with the Z-type part and the flat plate part without interference, and then co-curing and molding them.

[0006] Optionally, measuring the thickness difference of the prepreg before and after curing and using it as a reference interference quantity includes: determining the uncured thickness of the prepreg under a specified layup and the net thickness after standard curing; and calculating the reference interference quantity based on the uncured thickness and the net thickness after standard curing.

[0007] Optionally, the construction of the dual-mold molding system, used for pre-compaction and co-curing respectively, includes: manufacturing a standard molding mold; manufacturing a pre-forming mold for pre-compacting the C-shaped part; and performing matching verification on the standard molding mold and the pre-forming mold.

[0008] Optionally, the manufacturing pre-forming mold, used for pre-compacting the C-shaped part, includes: using the surface corresponding to the C-shaped part in the standard forming mold as a reference, uniformly indenting it inward along the normal direction of the web of the C-shaped part by a preset thinning amount, as shown below:

[0009] in, Indicates the amount of thinning; Indicates the correction factor; This represents the difference between the uncured thickness of the prepreg and the net thickness after curing.

[0010] Optionally, the correction coefficient The selection is based on the volatile matter content and thickness difference coefficient of the material, which are within the range of 10% to 100%. When the volatile matter content of the prepreg is >2% or the thickness difference coefficient before and after curing is >1.15, a value of 60% ≤ is selected. ≤100%; when the volatile content of the prepreg is ≤2% or the thickness difference coefficient before and after curing is ≤1.15, select 10%≤ ≤60%.

[0011] Optionally, the offline pre-compacting treatment of the C-shaped part includes: laying the C-shaped part prepreg on the preforming mold and vacuum sealing it; and pre-compacting the vacuum-sealed C-shaped part prepreg.

[0012] Optionally, the step of vacuum sealing the C-type prepreg on the preforming mold includes: laying the cut prepreg layer by layer on the thinned and modified preforming mold, and vacuuming and compacting after every 2 to 3 layers; after laying, laying the breathable felt, the release film and the vacuum bag on the thinned and modified preforming mold in sequence, and using sealing strips to completely seal the vacuum bag and the edge of the mold.

[0013] Optionally, the pre-compacting treatment of the C-type prepreg after vacuum sealing includes: controlling the temperature between 60℃ and 90℃, setting the pressure between 0.1 MPa and 0.7 MPa, and holding the temperature and pressure for 15 minutes to 60 minutes.

[0014] Optionally, the step of non-interference assembly of the pre-compacted C-shaped part with the Z-shaped part and the flat part, and co-curing them includes: transferring the pre-compacted C-shaped part to a standard mold and assembling it with the Z-shaped part and the flat part; and co-curing the assembled C-shaped part with the Z-shaped part and the flat part.

[0015] Optionally, the co-curing molding of the assembled C-shaped part, Z-shaped part, and flat part includes: vacuum bagging the assembled C-shaped part, Z-shaped part, and flat part; sending the packaged C-shaped part, Z-shaped part, and flat part into an autoclave; applying temperature and pressure according to the standard curing process curve of the composite material system; and completing the co-curing molding after heat and pressure maintenance.

[0016] Compared with the prior art, the beneficial effects of this application are as follows: This application introduces an independent pre-forming mold for offline pre-compaction compensation of C-shaped parts. First, it protects the expensive final standard mold from the risk of repeated modifications or damage, reducing mold costs and the barrier to entry. Second, this method can eliminate rigid interference and forced mold displacement problems in the assembly process of C-shaped, Z-shaped, and flat parts caused by the thickness difference before and after prepreg curing, avoiding web skewing and assembly gaps. Third, the pre-compaction process effectively removes interlayer air and volatiles before resin gelation, causing the thickness of the C-shaped part to converge earlier, thereby suppressing the formation of resin-rich triangular areas and pores at the bonding surface during the co-curing stage, significantly improving interlayer shear strength and internal quality. At the same time, this process can flexibly adjust the thinning correction amount of the pre-forming mold and match the corresponding pre-compaction parameters within the range of 10% to 100% according to the volatile content and thickness difference coefficient of different material systems, showing good adaptability and process robustness for both high and low thickness difference materials. Attached Figure Description

[0017] Figure 1 This is a schematic flowchart of a co-curing molding method for a J-type composite material structure provided in one embodiment of this application; Figure 2 This is a schematic diagram of the C-type and Z-type components in a J-type composite material structure; Figure 3 This is a schematic diagram illustrating the principle of assembly interference between Z-shaped parts and flat parts caused by excessive prepreg thickness in existing technologies. Figure 4 This is a schematic diagram of the thinning correction of the C-type preforming mold in this application; Figure 5 This is a schematic diagram showing the transfer of the C-shaped preform to a standard mold and the achievement of zero-gap bonding and co-curing after the thinning preforming mold process used in this application.

[0018] The annotations in the attached figures are explained as follows: 1. C-shaped part; 2. C-shaped part co-curing mold; 3. Flat part; 4. Flat part mold; 5. Z-shaped part; 6. Z-shaped part mold; 7. Triangular core material; 8. Prepreg laid on C-shaped part mold; 9. Prepreg laid on Z-shaped part mold; 10. Thickness difference; 11. Thinning amount. Detailed Implementation

[0019] Specific embodiments of this application will now be described in detail with reference to the accompanying drawings. While specific embodiments of this application are shown in the drawings, it should be understood that this application can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art.

[0020] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions in the specification are preferred embodiments for carrying out this application; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of this application. The scope of protection of this application shall be determined by the appended claims.

[0021] To facilitate understanding of the embodiments of this application, the following will provide further explanation and description with reference to the accompanying drawings and specific embodiments, and the accompanying drawings do not constitute a limitation on the embodiments of this application.

[0022] Figure 1 This is a schematic flowchart of a co-curing molding method for a J-type composite material structure provided in one embodiment of this application, as shown below. Figure 1 As shown, the method includes the following steps: S100: Measure the thickness difference of the prepreg before and after curing and use it as a reference interference quantity; S200: Constructs a dual-mold molding system, used for pre-compaction and co-curing respectively; S300: Offline pre-compaction treatment for C-type parts; S400: The pre-compacted C-shaped parts, Z-shaped parts, and flat parts are assembled without interference and co-cured.

[0023] Figure 2 This is a schematic diagram of the C-type and Z-type components in a J-type composite material structure; Figure 3 This is a schematic diagram illustrating the principle of assembly interference between Z-shaped parts and flat parts caused by excessive prepreg thickness in existing technology. For example... Figure 2 and Figure 3 As shown, C-shaped component 1, Z-shaped component 5, flat component 3, and triangular core material 7 together constitute the main structure of the J-shaped stringer. Among them, C-shaped component 1 is laid on C-shaped component co-curing mold 2, Z-shaped component 5 is laid on Z-shaped component mold 6, and flat component 3 is placed on flat component mold 4.

[0024] In another exemplary embodiment, step S100, measuring the thickness difference of the prepreg before and after curing and using it as a reference interference amount, includes the following steps: S101: Determine the uncured thickness of the prepreg under a specified layup. and the net thickness after standard curing ; In this step, firstly, prepreg test pieces are prepared according to the actual layup method (including the number, direction, and sequence of layups) of C-type, Z-type, or flat components in the J-type stringer. Secondly, the uncured thickness of the prepreg under the specified layup is measured. Specifically, this includes: laying the laid-up uncured prepreg specimen flat on a flat reference surface at room temperature; using a precision thickness gauge (such as a digital micrometer or ultrasonic thickness gauge) to uniformly select no fewer than 5 measurement points on the specimen surface; applying constant, slight contact pressure during measurement (avoiding artificial compression), and recording the thickness values ​​at each point; calculating the arithmetic mean as the uncured thickness in this layup state. It should be noted that the prepreg layers contain air, volatiles, and uncompressed fiber layers, resulting in an initial thickness significantly greater than the cured thickness. This difference is the root cause of assembly interference. Therefore, accurate measurement... It forms the basis for quantifying the degree of interference and designing compensation schemes.

[0025] Next, take prepreg samples with the same layup pattern and cure them according to the standard curing process for this material system (such as autoclave curing profile: heating rate, holding temperature, pressure, cooling rate, etc.). After curing, cool the samples to room temperature and select no less than 5 measurement points in the same type of location using the same thickness gauge. Measure the actual thickness of the cured samples and calculate the average value as the net thickness after standard curing. .

[0026] S102: Based on uncured thickness and the net thickness after standard curing The specific formula for calculating the reference interference is as follows: .

[0027] in, This represents the difference between the uncured thickness of the prepreg and the net thickness after curing, i.e., the reference interference, in mm.

[0028] The purpose of calculating the baseline interference is to quantify the potential assembly interference caused by the thickness change before and after the prepreg is cured, which can serve as a basis for subsequent mold thinning correction.

[0029] In another exemplary embodiment, step S200 involves constructing a dual-mold molding system for pre-compaction and co-curing, including the following steps: S201: Manufacturing standard molding dies; In this step, this embodiment follows the final design drawings of the J-shaped stringer, using the net thickness after curing. Based on this standard, standard forming molds are manufactured using Invar alloy or high-quality mold steel. The mold's surface dimensions strictly adhere to the "net dimension design principle," meaning it is machined entirely according to the theoretical shape of the cured part. The surface tolerance is controlled within ±0.05mm, and the surface roughness reaches Ra≤0.8μm. Precision positioning pins, reference surfaces, and segmented structures are included for the accurate assembly and co-curing positioning of subsequent C-shaped parts, Z-shaped parts, core materials, and flat parts.

[0030] S202: Manufacturing preforming molds for pre-compacting C-shaped parts; In this step, this embodiment uses the surface corresponding to the C-shaped part in the standard molding die as a reference, and uniformly shrinks inward by a preset thinning amount along the normal direction of the web of the C-shaped part. (like Figure 4 As shown in mark 11), manufacture a set of dedicated preforming molds, such as... Figure 4 As shown, Figure 4 In the middle, the amount of thinning According to the formula The calculation determines that, Prepreg uncured thickness Net thickness after curing The difference, correction factor The coefficient is selected based on the volatile content of the material and the thickness difference coefficient, which are within the range of 10% to 100%. For example, when the volatile content of the prepreg is >2% or there is a thickness difference coefficient before and after curing. When >1.15, select 60%≤ ≤100% to provide a larger initial compression space; when the volatile content of the prepreg is ≤2% or there is a thickness difference coefficient before and after curing. When ≤1.15, select 10%≤ ≤60% to avoid excessive compression that could damage the fibers.

[0031] In addition, the preforming mold can be made of aluminum alloy or metal material with a coefficient of thermal expansion that matches that of the standard mold. The surface indentation accuracy is controlled within ±0.02mm. The surface is coated with a release agent and a draft angle of 1°~3° is set to facilitate the smooth demolding of the C-shaped preform after pre-compaction.

[0032] S203: Verify the matching of standard molding dies and pre-forming dies.

[0033] In this step, the manufactured standard molding mold and the pre-forming mold are first calibrated to confirm the accuracy of the geometric correspondence between their positioning reference surfaces, positioning pin holes, and key surface features. Then, a simulation verification is performed, including: laying the prepreg onto the pre-forming mold and completing the pre-compacting process according to the set procedure; demolding the resulting C-shaped preform from the pre-forming mold; and then attempting to place it in the corresponding position on the standard molding mold to check for problems such as assembly interference, excessive fitting gaps, or positioning misalignment.

[0034] In another exemplary embodiment, step S300 involves offline pre-compacting of the C-shaped part, including the following steps: S301: Lay the C-type prepreg onto the preforming mold and vacuum seal it; In this step, the prepreg is first laid layer by layer on the thinned and modified preforming mold according to the layup sequence and direction of the J-type stringer and C-type component. After every 2 to 3 layers, vacuum compaction is performed (5 to 10 minutes) to remove interlayer gas and reduce bridging. After the laying is completed, a breathable felt, a release film and a vacuum bag are laid on the thinned and modified preforming mold in sequence. The vacuum bag and the edge of the mold are completely sealed with sealing strips. A thermocouple is placed in a suitable position inside the bag to monitor the temperature. Then, the vacuum pipeline is connected and the vacuum pump is turned on to make the vacuum degree inside the bag reach more than 0.08 MPa and maintain it for at least 5 minutes. After confirming that there is no leakage, it is ready for use.

[0035] S302: Pre-compact the prepreg material of the vacuum-sealed C-type part.

[0036] In this step, the vacuum-sealed preform mold is placed into an autoclave or heat-sealing equipment and subjected to heating and pressurization according to preset pre-compaction process parameters: the temperature is controlled between 60℃ and 90℃ (below the resin gel point), the pressure is set between 0.1 MPa and 0.7 MPa, and the heat and pressure holding time is 15 minutes to 60 minutes. During the process, air and volatiles between the prepreg layers are expelled under the dual action of vacuum and pressure, the fiber layer gradually becomes denser, and the thickness of the C-shaped part increases from the initial thickness. Shrinking to intermediate thickness and approaching Meanwhile, because the processing temperature is strictly below the resin gel point, the resin only undergoes physical flow and does not enter deep chemical cross-linking, so that the resin on the surface of the C-type part retains its activity, providing reliable chemical bonding ability for subsequent co-curing and bonding with the Z-type part and the flat part.

[0037] In another exemplary embodiment, in step S400, the pre-compacted C-shaped part, Z-shaped part, and flat plate are assembled without interference and co-cured, including the following steps: S401: Transfer the pre-compacted C-shaped part to the standard mold and assemble it with the Z-shaped part and the flat part; In this step, after pre-compaction, the C-shaped preform is demolded from the pre-forming mold and transferred to the corresponding position in the standard forming mold. Subsequently, Z-shaped prepreg and flat prepreg are laid or placed sequentially. The Z-shaped and flat prepregs can remain in their original, uncompacted state or be compacted only by cold vacuuming. Figure 5 As shown, the regularized geometric shape of the C-shaped part 1 preform is used as a positioning reference to guide the Z-shaped part mold 6 to be accurately positioned, so that the web of the Z-shaped part 5 remains vertical and the lower edge strip and the flat part 3 are naturally and with zero gap fit. At the same time, the relative positions between each component are checked, and the overall assembly is completed after confirming that there is no assembly interference.

[0038] like Figure 3 As shown, there is a significant thickness difference 10 between the prepreg 8 laid on the C-shaped mold and the prepreg 9 laid on the Z-shaped mold, which causes the Z-shaped part 5 to fail to properly fit with the flat part 3, resulting in gaps and web misalignment.

[0039] S402: Co-curing the assembled C-type parts, Z-type parts, and flat parts.

[0040] In this step, the assembled structure is vacuum-sealed and then placed in an autoclave. Temperature and pressure are applied according to the standard curing process curve of the composite material system. Taking a typical carbon fiber / epoxy resin system as an example, the temperature is raised to 180°C, the pressure is increased to 0.6 MPa, and the temperature and pressure are maintained for a sufficient time to allow the resin to fully cross-link and cure. During the curing process, since the C-shaped part has achieved thickness convergence and has a small amount of resin flow due to pre-compaction treatment, while the Z-shaped part and the flat part still maintain a relatively abundant amount of resin flow, the excess resin in the Z-shaped part and the flat part will be slightly supplemented to the bonding area by utilizing this difference in curing kinetics. This can prevent the bonding surface from being poor in resin and avoid the resin-rich defects formed by a large amount of resin flowing in. Finally, the three parts are integrated to form a J-shaped composite material component with a dense structure and good interfacial bonding.

[0041] The technical solution of this application will be further described below through specific embodiments and comparative examples.

[0042] Example 1 This embodiment aims to fabricate a 2000mm long aerospace-grade carbon fiber / epoxy resin J-shaped stringer. First, T800 grade unidirectional prepreg was selected, and 20 layers of C-shaped prepreg were laid. Measurements showed a thickness difference between the prepreg and cured layers, with the uncured layer being [not specified]. It is 3.80mm, while the standard cured net thickness is... The reference interference is 3.60 mm. The thickness is 0.20mm. Based on this, a set of standard steel molds (designed according to 3.60mm) and a set of aluminum alloy preforming molds are manufactured. The preforming molds are set with a correction factor K of 80%, that is, a uniform inward cut of 0.16mm (S=0.16mm) on the basis of the standard profile.

[0043] In the pretreatment stage, 20 layers of C-shaped prepreg were laid onto a preforming mold, and other components were laid according to the designed mold, then fed into a heat-sealing press. The process was set as follows: 80℃ (low viscosity zone), 0.3MPa pressure held for 30 minutes. After treatment, the thickness of the C-shaped part shrank to approximately 3.63mm, with a dense surface and physical rigidity. The preform was then demolded and transferred to a standard mold; due to its thickness being very close to the design value, it fit well. Next, the pretreated Z-shaped and flat parts were laid. Mold closing inspection showed that the Z-shaped part was successfully positioned without lateral extrusion, and the web verticality deviation was less than 0.1°.

[0044] Finally, the parts were sealed in vacuum bags and placed in an autoclave for standard curing at 180°C and 0.6 MPa. During curing, the resin flow between the Z-shaped and flat parts effectively filled the tiny gaps. Evaluation showed that the part dimensions met the ±0.1 mm tolerance, the bonding area had no resin-rich core or pores, and the shear strength reached 98% of the base material.

[0045] Example 2 This embodiment targets a fabric prepreg system with high volatile content and a thickness difference before and after curing. The design thickness of the C-shaped part was measured. The thickness is 4.0mm, and there is a thickness difference before and after curing. The interference is 4.8 mm. Up to 0.8mm. In view of this, the correction factor K is set to 100%, that is, the preform mold is 0.8mm thinner than the standard mold.

[0046] During pretreatment, high-pressure parameters were used: 90℃, 0.5MPa, and holding pressure for 60 minutes to forcibly compress the C-shaped part to approximately 4.05mm and expel a large amount of volatiles. After transfer to a standard mold for co-curing, the porosity of the part decreased from the conventional 1.5% to 0.3%, and the difficulties in mold closing and the warping of the Z-shaped part caused by the thickness difference between the material before and after high-curing were completely resolved, verifying the effectiveness of the full compensation strategy.

[0047] Example 3 This embodiment targets Automated Tape Laying (ATL) prepregs, which have high initial density and low interference. Only 0.15mm. A correction factor is set to avoid excessive compression that could damage the fibers. The reduction is 30%, which means the pre-forming mold is thinned by 0.045mm.

[0048] The pretreatment employed a mild process: 60℃, 0.1MPa for 15 minutes, primarily for shaping. Results showed that the C-shaped preform maintained excellent fiber straightness without buckling. After co-curing, the resin distribution at the bonding surface was uniform, with no resin deficiency, demonstrating that minimal compensation was sufficient to meet the assembly requirements of materials with thickness differences before and after low-curing.

[0049] Example 4 This embodiment involves a J-shaped truss with a gradually varying thickness along its length: 24 layers of C-shaped members at the root ( =0.3mm), 16 layers at the tip ( =0.2mm). The preforming mold adopts a variable cross-section thinning design with a uniform correction coefficient K=90%.

[0050] Calculations showed that the root was thinned by 0.27 mm and the tip by 0.18 mm, with linear transition cutting applied to the mold surface. Results indicated that the pre-compacted C-shaped part exhibited good dimensional convergence along its entire length, and the stringer showed minimal torsional deformation after co-curing, with a straightness better than 0.5 mm / m. This successfully solved the problem of inconsistent shrinkage in variable thickness structures.

[0051] Example 5 This embodiment verifies the feasibility under conditions without an autoclave. In step S302, instead of using a heat sealing device, the pre-formed mold for sealing the vacuum bag is placed in a forced-air drying oven, and pre-compacted by using vacuum pressure (approximately 0.1 MPa) combined with heating at 85°C for 45 minutes.

[0052] Because vacuum compaction is less effective than positive pressure, a correction factor K was set to 60% to allow for more margin. Evaluation showed that although the preform density was slightly lower, major assembly interferences were eliminated, and the final part quality was satisfactory, demonstrating the method's good compatibility with low-cost equipment.

[0053] Comparative Example 1 Using the same batch of materials as in Example 1, 20 layers of C-shaped parts (3.80mm) were directly laid on a standard mold, and the Z-shaped part mold was forcibly installed. During assembly, the C-shaped parts were significantly higher than the reference surface, causing the Z-shaped part mold to be lifted, and a wedge-shaped gap of 0.18~0.25mm was formed between the lower edge strip and the flat plate.

[0054] After curing, cross-section observation revealed that the web of the Z-shaped part tilted outward at 1.5°, the bonding area was filled with pure resin and contained large-sized pores (porosity > 2.0%). Mechanical testing showed that the interlaminar shear strength was only 75% of that in Example 1, confirming that the thickness difference before and after curing severely impaired the performance of the part.

[0055] Comparative Example 2 A pre-forming mold with a thinning amount S=1.5×△=0.30mm was manufactured for over-thinning testing. Due to the small mold cavity, the prepreg was subjected to huge lateral compression during pre-pressing, resulting in fiber wrinkles on the surface of the C-shaped part after demolding.

[0056] After being transferred to a standard mold, a gap formed between the preform and the mold due to the preform's excessive thinness (less than the design thickness). Following co-curing, resin buildup spots appeared on the surface of the part, and fiber wrinkles led to a significant decrease in compressive strength. This result strongly supports the correction factor. It should be controlled within the range of 10% to 100%, as excessive compensation is actually harmful.

[0057] Furthermore, Table 1 illustrates the processing effects of the above embodiments and comparative examples: Table 1

[0058] As shown in Table 1, by adjusting the correction factor ( With values ​​ranging from 30% to 100% and matching corresponding pretreatment processes (from mild heat sealing to strong heat sealing, and even oven vacuum bag solutions), the method of this application can effectively eliminate assembly interference, avoid fiber buckling and resin-rich defects for different material characteristics (such as volatile content and thickness difference) and structural requirements (such as variable thickness design). In the examples, it achieves co-curing quality with accurate dimensions, low porosity and high strength. In contrast, the lack of compensation or over-compensation in the comparative examples resulted in part damage such as Z-shaped part skewing, gap porosity or fiber wrinkling, thus verifying the necessity of controlling the correction coefficient within the range of 10% to 100% and its synergistic optimization with the process.

[0059] The present application has been described in detail above with reference to specific embodiments and exemplary examples. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and implementation methods of the present application without departing from the spirit and scope of the present application, and all such modifications and improvements fall within the scope of the present application. The scope of protection of the present application is determined by the appended claims.

Claims

1. A method for co-curing and molding a J-type composite material structure, characterized in that, The method includes: The thickness difference of the prepreg before and after curing is measured and used as a reference interference quantity; A dual-mold molding system was constructed, used for pre-compaction and co-curing respectively; Offline pre-compaction treatment is performed on the C-type parts; The pre-compacted C-shaped parts are assembled with the Z-shaped parts and flat parts without interference, and then co-cured.

2. The method according to claim 1, characterized in that, The measurement of the thickness difference of the prepreg before and after curing, used as a reference interference quantity, includes: Determine the uncured thickness and net thickness of the prepreg under specified layup; The reference interference is calculated based on the uncured thickness and the net thickness after standard curing.

3. The method according to claim 1, characterized in that, The aforementioned dual-mold molding system, used for pre-compaction and co-curing respectively, includes: Manufacturing standard molding dies; Manufacturing preforming molds for pre-compacting C-shaped parts; Verify the matching of standard forming molds and preforming molds.

4. The method according to claim 3, characterized in that, The manufacturing preform mold, used for pre-compacting C-shaped parts, includes: Using the surface corresponding to the C-shaped part in the standard forming mold as a reference, a preset thinning amount is uniformly reduced inward along the normal direction of the web of the C-shaped part, as shown below: in, Indicates the amount of thinning; Indicates the correction factor; This represents the difference between the uncured thickness of the prepreg and the net thickness after curing.

5. The method according to claim 4, characterized in that, The correction coefficient The selection is based on the volatile matter content and thickness difference coefficient of the material, which are within the range of 10% to 100%. When the volatile matter content of the prepreg is >2% or the thickness difference coefficient before and after curing is >1.15, a value of 60% ≤ is selected. ≤100%; when the volatile content of the prepreg is ≤2% or the thickness difference coefficient before and after curing is ≤1.15, select 10%≤ ≤60%.

6. The method according to claim 1, characterized in that, The offline pre-compaction treatment of the C-type parts includes: The C-type prepreg is laid on the preforming mold and then vacuum sealed. The prepreg material of the vacuum-sealed C-type part is pre-compacted.

7. The method according to claim 6, characterized in that, The step of laying the C-type prepreg onto the preforming mold and then vacuum sealing it includes: The cut prepreg is laid layer by layer on the thinned and modified preform mold. After every 2 to 3 layers, vacuum compaction is performed. After the lining is completed, the breathable felt, release film and vacuum bag are laid in sequence on the thinned and modified preformed mold, and the vacuum bag and mold edge are completely sealed with sealing strips.

8. The method according to claim 6, characterized in that, The pre-compacting treatment of the C-type prepreg after vacuum sealing includes: The temperature is controlled between 60℃ and 90℃, the pressure is set between 0.1 MPa and 0.7 MPa, and the heat and pressure holding time is between 15 minutes and 60 minutes.

9. The method according to claim 1, characterized in that, The process of assembling the pre-compacted C-shaped part, Z-shaped part, and flat plate part without interference, and then co-curing them, includes: The pre-compacted C-shaped parts are transferred to a standard mold and assembled with the Z-shaped parts and flat parts; The assembled C-shaped parts, Z-shaped parts, and flat parts are co-cured and molded.

10. The method according to claim 9, characterized in that, The process of co-curing and molding the assembled C-type component, Z-type component, and flat plate component includes: The assembled C-type parts, Z-type parts, and flat parts are vacuum-sealed in bags. The packaged C-shaped parts, Z-shaped parts, and flat parts are placed into an autoclave. Temperature and pressure are applied according to the standard curing process curve of the composite material system. After heat and pressure are maintained, co-curing is completed.

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