A method of integrating a braided cylinder structure with a composite material

Abstract

The application discloses a method for weaving a cylinder structure integrated composite material, and belongs to the technical field of thermoplastic composite material structures. The method uses a vacuum-assisted resin molding transfer process to weave thermoplastic resin and carbon fibers into a cylinder structure integrated composite material. The specific steps are as follows: thermoplastic resin and a curing agent are used as raw materials to prepare a thermoplastic resin colloidal solution; a release agent is applied to the inner surface of a cleaned mold, the release agent is dried, and dried carbon fibers are placed in the mold, the upper and lower molds are combined, and screws are fixed; the thermoplastic resin colloidal solution is poured into a syringe, a cover is sealed, an inlet opening switch and an outlet opening switch are opened, glue injection is performed, all switches are closed after glue injection is completed, and curing treatment is performed on the whole mold, and the mold is cooled to room temperature to obtain the composite material. The method can significantly improve the performance of the composite material.

Description

Technical Field

[0001] This invention belongs to the field of thermoplastic composite material structure technology, and particularly relates to a method for integrating a woven cylindrical structure with a composite material. Background Technology

[0002] Compared to traditional metal materials, composite materials possess higher specific strength, specific stiffness, high-temperature resistance, and corrosion resistance, and are currently widely used in aerospace, automotive, shipbuilding, and construction industries. Based on the resin matrix, composite materials can be broadly classified into two categories: thermosetting composites and thermoplastic composites. Thermosetting composites have a longer history, and their structural design and molding processes are relatively mature. Currently, most commonly used composite materials are thermosetting. Thermosetting resins are molded once and cannot be altered, while thermoplastic resins are melted and reused without significant changes to their physical and mechanical properties. This characteristic allows thermoplastic composites to be structurally joined using ultrasonic welding. Furthermore, compared to thermosetting composites, thermoplastic composites have higher fracture toughness, damage tolerance, and impact resistance, and also offer advantages such as reprocessability, ease of structural repair, room-temperature storage of prepregs, and high production efficiency. Therefore, thermoplastic composites are increasingly being applied in high-end equipment fields, demonstrating greater application prospects and trends.

[0003] Vacuum-Assisted Resin Transfer Molding (VARTM) is a composite molding process that utilizes a vacuum environment to guide and optimize the flow and distribution of resin within fiber-reinforced materials, and to create high-performance composite structures through a chemical curing process. Compared to other molding processes, it is more suitable for composites of large-size, irregularly shaped materials. By using a vacuum environment, it achieves uniform resin distribution, significantly reducing bubbles and defects, thereby improving the overall quality of the finished product. Furthermore, VARTM is more efficient than traditional resin transfer methods, reducing resin waste. This method also contributes to environmental protection by reducing emissions of volatile organic compounds (VOCs). Overall, VARTM is an efficient, economical, and environmentally friendly composite material manufacturing technology.

[0004] The fabrication of composite structural components typically involves the assembly of multiple parts, which may lead to an increase in seams and connection points, thereby reducing the overall integrity and strength of the structure. Therefore, the optimization of composite structural components has become an increasingly important issue. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a method for creating an integrated woven cylindrical structure from composite materials, utilizing the VARTM composite molding process to weave thermoplastic composite materials into an integrated cylindrical structure product.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for creating an integrated hollow cylindrical composite material involves using a vacuum-assisted resin molding transfer process to combine thermoplastic resin with carbon fiber fabric of an integrated hollow cylindrical structure, thereby weaving the composite material into an integrated cylindrical structure.

[0007] Furthermore, the method specifically includes the following steps: A thermoplastic resin colloidal solution is prepared using thermoplastic resin and curing agent as raw materials; Apply a release agent to the cleaned inner surface of the mold. After the release agent dries, put in the dried carbon fiber, close the upper and lower molds, and fix them with screws. Pour the thermoplastic resin colloidal solution into a syringe, seal the syringe, open the inlet and outlet switches, inject the resin, close all switches after injection, cure the entire mold, and cool it to room temperature to obtain the composite material.

[0008] Furthermore, the mass ratio of the thermoplastic resin to the curing agent is 3:1.

[0009] Furthermore, the carbon fiber has a hollow cylindrical structure filled with a foam core layer.

[0010] Furthermore, the specific process of the injection is as follows: the pressure value is 2 bars when the injection begins, the pressure is adjusted to 5 bars when the thermoplastic resin colloidal solution flows into the mold, and the outlet switch is closed to maintain pressure when the thermoplastic resin flows out of the mold outlet. During this stage, the thermoplastic resin will diffuse into the unimpregnated pore areas until it is completely filled.

[0011] Furthermore, during the glue injection process, the mold containing the sample, the syringe, and the connecting tube all need to be heated to 60°C.

[0012] The present invention also provides a composite material with an integrated cylindrical structure prepared by the method described above.

[0013] This invention also provides an application of a composite material with an integrated cylindrical structure in the aerospace, automotive, or military fields. Compared with the prior art, the present invention has the following advantages and technical effects: The integrated fabrication method for braided composite cylindrical structures proposed in this invention significantly enhances structural performance, reduces weight, and simultaneously lowers manufacturing complexity and cost. This method improves the load-bearing capacity and impact resistance of the cylindrical structure through a continuous and uniform fiber structure, while also resulting in better fatigue life. Integrated fabrication also improves production efficiency and design flexibility, reduces material waste, and meets environmental and sustainability requirements. Furthermore, it increases structural safety and reliability, particularly in aerospace, automotive, and military fields where the demand for lightweight, high-performance materials is growing. Attached Figure Description

[0014] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is the finite element model of the carbon fiber structure in this invention; Figure 2 This is a three-dimensional model of the PVC core layer structure filled into carbon fiber in this invention; Figure 3 This is the finite element model of the finished cylindrical structure obtained by the present invention; Figure 4 This is a schematic diagram of the VARTM composite process; Figure 5 This is a process flow diagram for the preparation of the composite material with an integrated cylindrical structure according to the present invention; Figure reference numerals: a-vacuum pump; b-sealant; c-core mold; d-carbon fiber; e-vacuum bag film; f-injection base; g-drain tube; h-thermoplastic resin; i-drain net; j-release cloth; k-mold; l-resin collector; 1-carbon fiber; 2-carbon fiber; 3-foam core layer. Detailed Implementation

[0015] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0016] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0017] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0018] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0019] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0020] The weaving described in this invention refers to the process of combining thermoplastic resin with carbon fiber fabric with an integrated hollow cylindrical structure.

[0021] This invention utilizes the VARTM composite molding process to weave thermoplastic composite materials into a single cylindrical structure. The demand for integrated fabrication of woven composite cylindrical structures stems primarily from their ability to significantly enhance structural performance, reduce weight, and simultaneously lower manufacturing complexity and cost. This method improves the load-bearing capacity and impact resistance of the cylindrical structure through a continuous and uniform fiber structure, while also resulting in better fatigue life. Integrated fabrication also improves production efficiency and design flexibility, reduces material waste, and meets environmental and sustainability requirements. Furthermore, it increases structural safety and reliability, particularly in aerospace, automotive, and military fields where the demand for lightweight, high-performance materials is increasing. Therefore, the integrated composite fabrication of woven cylindrical structures is an important technology with broad application prospects in modern industry. The specific technical solution is as follows: A method for integrating a braided cylindrical structure with a composite material includes the following steps: (1) In order to avoid the formation of pore defects by moisture in the preform during the composite process, the carbon fiber (also called preform) with hollow structure of cylinder is placed in an oven at 60°C for 10 hours before composite and weighed before composite; then the thermoplastic resin and curing agent are fully mixed in a mass ratio of 3:1 to prepare a thermoplastic resin colloidal solution. In order to eliminate a large number of bubbles, an ultrasonic cleaner is used to vibrate it for 5 minutes until the bubbles are completely eliminated. (2) Connect the rubber tube between the syringe, mold and vacuum pump, wipe and clean the inner surface of the equipment, and then apply the release agent (PMR release agent) evenly to all inner surfaces of the mold, applying it twice with a 20-minute interval in between; (3) After the release agent dries, place a sealing strip on the mold sealing groove and put in the pre-dried hollow carbon fiber. Then close the upper and lower molds and fix the screws. (4) After the mold is closed, pour the pre-defoamed thermoplastic resin colloidal solution into the syringe, screw on the syringe cap, open the inlet and outlet switches, and perform vacuuming (i.e., injection). After 2 minutes, close the outlet switch, i.e. the connection switch between the mold and the vacuum pump, and observe the air pressure parameter table of the RTM machine (the sensor is located at the top of the syringe). If the air pressure index is maintained at the lowest value during vacuuming, it proves that there is no problem with the airtightness of all connections. To ensure the fluidity of the thermoplastic resin during the injection process, the mold is placed in a 60°C oven, and the syringe and connecting tube are heated to 60°C. The maximum pressure value is set to 2 bar at the beginning of the injection. When the thermoplastic resin flows into the mold, the pressure is changed to 5 bar (so that the flow rate will automatically adjust the pressure value according to the smoothness, and will not cause the joint to burst due to excessive pressure). After the thermoplastic resin flows out of the mold outlet, the outlet switch is closed to maintain pressure. During this stage, the thermoplastic resin will diffuse into the pore areas of the unimpregnated preform until it is completely filled. (5) After the glue injection is completed, close all pipe switches, cut the pipes and put the mold into the oven. Cure at 70°C for 6 hours. Finally, put on a gas mask and clean the inside of the syringe with acetone. After curing is complete, take out the mold and cool it to room temperature. Then open the mold and take out the composite material (i.e. composite material) and weigh it to calculate the fiber volume fraction.

[0022] In the following embodiments of the present invention, the resin used is a thermoplastic resin. The specific type is not considered within the scope of the invention's inventive step. To further derive a specific product, polyvinyl chloride (PVC) is used in the following embodiments. Similarly, the selection of the curing agent is not considered within the scope of the invention's inventive step; it is sufficient to achieve the effects described in the invention. To further derive a specific product, diisophorone peroxide (DCP) is used as the curing agent in the following embodiments. PVC itself is a colloidal solution and does not cure after mixing with the curing agent. Instead, the heat treatment during the dispensing process promotes the gradual curing of the resin.

[0023] The mass ratio of the thermoplastic resin to the carbon fiber is 2:3.

[0024] This invention uses the VARTM composite molding process to weave carbon fiber resin composite material into a cylindrical shape and inserts a foam core layer into the structural layer. This method can significantly improve the explosion resistance of vulnerable parts.

[0025] The thickness of the carbon fiber in the hollow cylindrical structure is slightly higher than that of the mold gasket by 0.2-0.3mm, so that the upper and lower covers of the mold can fully press the preform after the mold is closed. This can prevent the resin from eroding and deforming the preform during the injection molding process.

[0026] The integrated composite material for cylindrical structures prepared by this invention can be used in aerospace components, vehicle body parts, submersible hulls, marine exploration equipment, vehicle armor, and protective structures. Due to its superior physical and mechanical properties, it is suitable for a wide range of industries and applications, especially in situations requiring lightweight, high strength, and good corrosion resistance.

[0027] Unless otherwise specified, "room temperature" in this invention refers to 20-30℃.

[0028] All raw materials used in this invention were purchased from the market.

[0029] The technical solution of the present invention will be further illustrated by the following embodiments.

[0030] Figure 4 This is a schematic diagram of the VARTM composite process; Figure 5 This is a flowchart of the preparation process.

[0031] Example 1 A method for integrating a braided cylindrical structure with a composite material includes the following steps: (1) The carbon fiber of the hollow cylinder structure is placed in an oven at 60°C and dried for 10 hours. It is weighed before composite and a foam core layer (PVC) is added inside to obtain a preform for later use. Polyvinyl chloride (PVC) and curing agent diisophorone peroxide (DCP) are thoroughly mixed at a mass ratio of 3:1 and ultrasonically vibrated for 5 minutes until all bubbles are eliminated to prepare a PVC colloidal solution for later use. (2) Connect the rubber tube between the syringe, mold and vacuum pump, wipe and clean the inner surface of the equipment, and apply the release agent (PMR release agent) evenly to all inner surfaces of the mold, applying it twice with a 20-minute interval in between; (3) After the release agent dries, place the sealing strip in the mold sealing groove, put in the preform, and then close the upper and lower molds and fix the screws. (4) After the mold is closed, pour the polyvinyl chloride colloidal solution into the syringe (the mass ratio of polyvinyl chloride colloidal solution to carbon fiber of the hollow cylinder is 2:3), screw on the syringe cap, open the glue inlet and glue outlet switches, and perform vacuuming (i.e. glue injection). After 2 minutes, close the glue outlet switch, i.e. the connection switch between the mold and the vacuum pump, and observe the air pressure parameter table of the RTM machine (the sensor is located at the top of the syringe). If the air pressure index is maintained at the lowest value when vacuuming, it proves that there is no problem with the airtightness of all connections. To ensure the fluidity of the thermoplastic resin during the injection process, the mold is placed in a 60°C oven, and the syringe and connecting tube are heated to 60°C. The maximum pressure value is set to 2 bar at the beginning of the injection. When the thermoplastic resin flows into the mold, the pressure is changed to 5 bar. After the thermoplastic resin flows out of the mold outlet, the outlet switch is closed to maintain pressure. During this stage, the thermoplastic resin will diffuse into the pore areas of the unimpregnated preform until it is completely filled. (5) After the glue injection is completed, close all pipe switches, cut the pipes, and place the entire mold into an oven to cure at 70°C for 6 hours. Finally, put on a gas mask, clean the inside of the syringe with acetone, and after complete curing, remove the mold and cool it to room temperature. Then, open the mold and remove the composite material (i.e., the composite material with an integrated cylinder structure). Remove the foam core layer and weigh it to calculate the carbon fiber volume fraction as 50%. The calculation formula is: ; Increasing the volume fraction of carbon fiber improves the stiffness, strength, and thermal conductivity of composite materials; however, excessively high volume fractions can lead to increased brittleness, decreased toughness, and negatively impact fatigue performance and thermal expansion. The selection of the volume fraction requires a balance between performance enhancement and the material's processability and durability.

[0032] The overall dimensional parameters of the integrated composite material model of the cylindrical structure prepared by the above method are as follows: model length: 2m, model radius: 0.5m, model thickness: 33mm, PVC core layer thickness: 15mm (see...). Figure 1-3 ).

[0033] Comparative Example 1 Similar to Example 1, except that in step (4), the mass ratio of polyvinyl chloride colloidal solution to carbon fiber in the hollow cylindrical structure is 3:7, and the volume fraction of carbon fiber in the resulting composite material is 30%.

[0034] Performance testing: 1. Load-bearing capacity test Experimental objective: To test the differences in load-bearing capacity between 50% carbon fiber composite materials, 30% carbon fiber composite materials, aluminum alloys (2xxx series), and epoxy resins, with a focus on measuring tensile strength, elastic modulus, compressive strength, and flexural strength.

[0035] Experimental methods: Standard: Performed according to ASTM D3039 tensile test standard.

[0036] Testing equipment: Universal testing machine.

[0037] Sample: A rectangular sample with a length of 250 mm, a width of 25 mm, and a thickness of 2 mm.

[0038] Loading rate: 1 mm / min, until the material fractures.

[0039] Table 1 Analysis of experimental results: Tensile strength: The tensile strength of the 50% carbon fiber composite material reaches 1500 MPa, which is significantly higher than that of the 30% carbon fiber composite material (1200 MPa) and aluminum alloy (400 MPa), proving that the increase in carbon fiber volume fraction significantly improves the strength.

[0040] Elastic modulus: The elastic modulus of 50% carbon fiber composite material is 75 GPa, which exceeds that of 30% carbon fiber composite material, aluminum alloy and epoxy resin, exhibiting higher stiffness.

[0041] Compressive strength: The compressive strength of the 50% carbon fiber composite material (1600 MPa) is significantly higher than that of the 30% carbon fiber composite material (900 MPa), and also higher than that of aluminum alloy (450 MPa) and epoxy resin (450 MPa), demonstrating the superior performance of the composite material under pressure.

[0042] Flexural strength: The flexural strength of the 50% carbon fiber composite (2200 MPa) is significantly higher than that of the 30% carbon fiber composite (1800 MPa), aluminum alloy (300 MPa) and epoxy resin (880 MPa), demonstrating the superior performance of the composite material under flexural load.

[0043] Conclusion: By increasing the carbon fiber volume fraction to 50%, the composite material of the present invention outperforms the prior art (30% carbon fiber composite and aluminum alloy) in terms of strength and stiffness, and is particularly suitable for applications requiring high strength, such as vehicle armor and aerospace components.

[0044] 2. Impact resistance test Experimental objective: To evaluate the differences in impact resistance between 50% carbon fiber composite materials, polyamide resin, and aluminum alloys.

[0045] Experimental methods: Standard: Izod impact test (ASTM D256 standard).

[0046] Sample: A sample with dimensions of 80mm × 10mm × 4mm.

[0047] Impact energy: 3.5J.

[0048] Table 2 Analysis of experimental results: The impact strength of 50% carbon fiber composite material is much higher than that of polyamide resin and aluminum alloy, and the broken area is significantly smaller, indicating that the composite material exhibits higher impact resistance and toughness under high impact energy.

[0049] 3. Fatigue life test Experimental objective: To test the performance of 50% carbon fiber composite material with aluminum alloy and epoxy resin under long-term fatigue load.

[0050] Experimental methods: Standard: Fatigue testing is conducted using a stepped loading method.

[0051] Loading frequency: 10Hz, loading stress range from 200MPa to 600MPa.

[0052] Specimen specifications: Circular fatigue specimen, 10 mm in diameter and 100 mm in length, with R = 0.1 (minimum stress / maximum stress).

[0053] Table 3 Analysis of experimental results: The fatigue limit and fatigue life of 50% carbon fiber composites are much higher than those of aluminum alloys, proving that they can maintain a longer service life under repeated loading, making them particularly suitable for structures with high cyclic loads.

[0054] 4. Explosion resistance test Experimental objective: To verify the performance of 50% carbon fiber composite material and aluminum alloy (2xxx series) under explosion simulation, and to compare it with aluminum alloy.

[0055] Experimental methods: Standard: Simulates the impact of a TNT explosion.

[0056] Explosion energy: 500J, 1500J, 3000J.

[0057] Table 4 Analysis of experimental results: The 50% carbon fiber composite material maintained high structural integrity under high-energy explosive impact, and the degree of damage after the explosion was significantly lower than that of aluminum alloy, indicating that the composite material has stronger explosion resistance.

[0058] 5. Lightweight, high-strength, and corrosion-resistant performance tests Experimental objective: To compare the lightweight and corrosion resistance of 50% carbon fiber composite materials, 30% carbon fiber composite materials, and aluminum alloys.

[0059] Table 5 Comparison of Lightweight Properties As can be seen from the table, the density of 50% carbon fiber composite material is about 50% lower than that of aluminum alloy, and also lower than that of 30% carbon fiber composite material, demonstrating the significant advantage of composite materials in terms of lightweight performance.

[0060] The 50% carbon fiber composite material in this invention has significant advantages in lightweight performance compared to the existing 30% carbon fiber composite material and traditional aluminum alloy, making it suitable for applications requiring high strength and lightweight, such as aerospace and vehicle armor.

[0061] Table 6 Comparison of Corrosion Resistance Salt spray corrosion: The corrosion rate of 50% carbon fiber composite material is 0.05 mm / year, which is much lower than that of aluminum alloy (1.2 mm / year), demonstrating excellent corrosion resistance.

[0062] Conclusion: 50% carbon fiber composite material exhibits a lower corrosion rate in salt spray corrosion environment, which is significantly superior to traditional aluminum alloy and 30% carbon fiber composite material, making it suitable for applications in marine, submersible and highly corrosive environments.

[0063] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for integrating a woven cylindrical structure into a composite material, characterized in that, Thermoplastic resin is combined with carbon fiber fabric of an integrated hollow cylindrical structure using a vacuum-assisted resin molding transfer process, and then woven into a composite material with an integrated cylindrical structure.

2. The method for integrating a braided cylindrical structure with a composite material according to claim 1, characterized in that, The method specifically includes the following steps: A thermoplastic resin colloidal solution is prepared using thermoplastic resin and curing agent as raw materials; Apply a release agent to the cleaned inner surface of the mold. After the release agent dries, put in the dried carbon fiber, close the upper and lower molds, and fix them with screws. Pour the thermoplastic resin colloidal solution into a syringe, seal the syringe, open the inlet and outlet switches, inject the resin, close all switches after injection, cure the entire mold, and cool it to room temperature to obtain the composite material.

3. The method for integrating a braided cylindrical structure with a composite material according to claim 2, characterized in that, The mass ratio of the thermoplastic resin to the curing agent is 3:

1.

4. The method for integrating a braided cylindrical structure with a composite material according to claim 2, characterized in that, The hollow cylindrical structure of the carbon fiber is filled with a foam core layer.

5. The method for integrating a braided cylindrical structure with a composite material according to claim 2, characterized in that, The specific process of injection is as follows: the pressure value is 2 bars when injection begins, the pressure is adjusted to 5 bars when the thermoplastic resin colloidal solution flows into the mold, and the outlet switch is closed to maintain pressure when the thermoplastic resin flows out of the mold outlet. During this stage, the thermoplastic resin will diffuse into the unimpregnated pore areas until it is completely filled.

6. The method for integrating a braided cylindrical structure with a composite material according to claim 2, characterized in that, During the glue injection process, the mold containing the sample, the syringe, and the connecting tube all need to be heated to 60°C.

7. The method for integrating a braided cylindrical structure with a composite material according to claim 2, characterized in that, The curing process refers to curing at 70°C for 6 hours.

8. A composite material with an integrated cylindrical structure prepared by the method according to any one of claims 1-7.

9. The application of a composite material with an integrated cylindrical structure as described in claim 8 in the aerospace, automotive, or military fields.

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