An integrated composite drive shaft and a layup process thereof

Abstract

The application discloses a kind of laying process of integral composite material transmission shaft in the technical field of composite material products, comprising the following steps: step 1) laying of the ring, corresponding ring position laying carbon fiber prepreg on the mold;Step 2) inner layer equal thickness area laying, along the flange on one side of mold through pipe section to the surface of flange on the other side, carbon fiber prepreg is laid to obtain inner layer;Step 3) outer layer thickening area laying, on the surface of inner layer along the position of both end pipe sections to flange head, carbon fiber prepreg is laid to obtain complete both end pipe sections and flange plate, the application can greatly reduce the self-weight of overall structure, reduce noise, reduce the energy loss of transmission system, improve the anti-vibration performance.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, and in particular to a drive shaft. Background Technology

[0002] Existing composite material drive shafts used in the aerospace field generally employ a combination structure where the connecting flange is metal and the straight cylindrical section is composite material. Various mechanical connections are used between the metal flange and the composite cylindrical body, or the structure of the metal-cylinder connection surface is altered. This results in a complex overall design. The connection structure not only adds extra weight but also causes stress concentration at the openings in the composite material during loading. Drive shafts are subjected to radial loads, axial loads, bending moments, and torques. The friction and slippage between the connecting parts and interfaces used in traditional shafts with metal flanges during vibration can affect their performance.

[0003] To address the aforementioned issues and optimize structural weight to the greatest extent possible, an integrated composite material drive shaft structure was designed, with the flange and cylinder being integrally molded from composite materials. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an integrated composite material drive shaft and its installation process, which can significantly reduce the overall structural weight, reduce noise, decrease energy loss in the transmission system, and improve vibration resistance.

[0005] The objective of this invention is achieved as follows: an integrated composite material drive shaft includes a hollow tube with flanges at both ends. The hollow tube comprises a middle section and two end sections, both of which are of equal thickness. The thickness of the end sections is greater than that of the middle section. The thickness of the end sections is the same as that of the flanges. A stop ring is provided at the opening of the end sections. The hollow tube, flanges, and stop rings are integrally formed using carbon fiber material.

[0006] As a preferred technical solution of the integrated composite material drive shaft of the present invention, the transition between the middle pipe section and the two end pipe sections adopts a variable diameter transition.

[0007] As a preferred technical solution of the integrated composite material drive shaft of the present invention, a dynamic balancing and molding area is provided in the middle of the middle pipe section.

[0008] A process for laying an integrated composite material drive shaft includes the following steps: Step 1) Laying the stop ring: Lay the carbon fiber prepreg on the mold at the position corresponding to the stop ring; Step 2) Laying the inner layer of equal thickness: The carbon fiber prepreg is laid along the flange on one side of the mold through the pipe section to the flange on the other side to obtain the inner layer; Step 3) Laying the outer thickened area: On the inner surface, carbon fiber prepreg is laid along the positions of the two pipe sections to the flange head to obtain complete two pipe sections and flanges.

[0009] As a preferred technical solution for the laying process of the integrated composite material drive shaft of the present invention, in step 1), when laying the stop ring, the mold is provided with a corresponding groove. The groove is set at both ends of the mold near the flange position. The carbon fiber prepreg is laid in the groove until the outer diameter of the stop ring is equal to the outer diameter of the mold.

[0010] As a preferred technical solution for the laying process of the integrated composite material drive shaft of the present invention, in step 2), the layers are laid one by one, and the layers are laid obliquely from the flange section on one side of the mold through the round pipe section to the flange section on the other side. After each layer is laid, a gap will be formed on the flange sections on both sides, which is filled with carbon fiber prepreg.

[0011] As a preferred technical solution for the laying process of the integrated composite material drive shaft described in this invention, after each layer is laid, the next layer of prepreg is laid at a distance away from the previous layer of prepreg, so that the gaps of the flange section are staggered from each other.

[0012] As a preferred technical solution for the laying process of the integrated composite material drive shaft of the present invention, in step 3), the layers are laid one by one, diagonally laid along the round tube section of the mold to the flange section. After each layer is laid, a gap will be formed on the flange section, which is filled with carbon fiber prepreg.

[0013] As a preferred technical solution for the laying process of the integrated composite material drive shaft described in this invention, after each layer is laid, the next layer of prepreg is laid at a distance away from the previous layer of prepreg, so that the gaps of the flange section are staggered from each other.

[0014] As a preferred technical solution for the laying process of the integrated composite material drive shaft of the present invention, it further includes laying carbon fiber prepreg in the middle of the dynamic balance mold repair area in the middle of the middle pipe section.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention uses composite materials to integrally form the flange with the central pipe section, which is a traditional metal flange. This significantly reduces the overall structural weight, noise, energy loss in the transmission system, and vibration resistance. It sets a precedent in the field of drive shaft applications, and the feasibility of the structure has been verified by experiments. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the transmission shaft structure in this invention.

[0018] Figure 2 This is a side view of the transmission shaft in this invention.

[0019] Figure 3 This is a schematic diagram of the three-layer prepreg in the pipe section in the laying process of this invention.

[0020] Figure 4 This is a schematic diagram of the three-layer prepreg in the flange section of the laying process in this invention.

[0021] Figure 5 This is a schematic diagram of the finite element analysis of the transmission shaft in this invention. Figure 1 .

[0022] Figure 6 This is a schematic diagram of the finite element analysis of the transmission shaft in this invention. Figure 2 .

[0023] Among them, 100 is hollow tube, 101 is middle pipe section, 102 is pipe sections at both ends, 103 is diameter transition, 104 is dynamic balance mold repair area, 200 is flange, 300 is stop ring, 401 is first layer of prepreg, 402 is second layer of prepreg, 403 is third layer of prepreg, 501 is first shear, 502 is second shear, and 503 is third shear. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1 As shown in the figure, an integrated composite material drive shaft includes a hollow tube with flanges at both ends. The hollow tube consists of a middle section and two end sections, both of which are of equal thickness. The thickness of the end sections is greater than that of the middle section, and the thickness of the end sections is the same as that of the flanges. A stop ring is provided at the opening of the end sections. The hollow tube, flanges, and stop rings are integrally formed using carbon fiber material.

[0026] It should be noted that drive shafts are subjected to the combined effects of radial loads, axial loads, bending moments, and torques. Traditional shafts using metal flanges experience friction and slippage between the connecting parts and interfaces during vibration, affecting their performance. To better meet the needs of drive shaft applications, a one-piece molded structure is designed. Metal drive shaft mechanical systems are prone to resonance during operation, which can cause loosening or fatigue failure of mechanical parts, generating noise and affecting shaft performance. The one-piece molded structure of carbon fiber composite drive shafts significantly reduces structural weight while increasing the natural frequency of the drive shaft. Reducing the number of mating interfaces not only avoids noise generation but also reduces energy loss in the transmission system and improves vibration resistance. Furthermore, carbon fiber composite drive shafts are corrosion-resistant, have a low coefficient of thermal expansion, and are suitable for harsh working environments. Carbon fiber composite drive shafts can be repaired using reinforcement methods, making maintenance simpler than with metal shafts and increasing their service life. Using a one-piece composite structure significantly reduces overall structural weight, reduces noise, lowers energy loss in the transmission system, and improves vibration resistance.

[0027] Furthermore, a diameter-reducing transition is used at the transition points between the middle pipe section and the two end pipe sections.

[0028] It should be noted that the thickened ends are due to the fact that the drive shaft primarily bears torque and not bending moment, or only a very small bending moment, while supporting other rotating components and transmitting power. To withstand the large instantaneous torque during drive shaft operation, the thickness of the flanges at both ends of the drive shaft has been increased. The thicker flanges allow for better connection with the connected components via connectors, ensuring strength and connection reliability.

[0029] Furthermore, a dynamic balancing and molding repair area is provided in the middle of the central pipe section.

[0030] It should be noted that since the drive shaft is always in a rotating state, it is necessary to perform dynamic balancing tests on the drive shaft. By designing a dynamic balancing mold repair area, the original drive shaft body will not be affected when performing dynamic balancing mold repair.

[0031] Example 2 A process for laying an integrated composite material drive shaft includes the following steps: Step 1) Laying the stop ring: Lay the carbon fiber prepreg on the mold at the position corresponding to the stop ring; Step 2) Laying the inner layer of equal thickness: The carbon fiber prepreg is laid along the flange on one side of the mold through the pipe section to the flange on the other side to obtain the inner layer; Step 3) Laying the outer thickened area: On the inner surface, carbon fiber prepreg is laid along the positions of the two pipe sections to the flange head to obtain complete two pipe sections and flanges.

[0032] This process enables the seamless laying of pipe sections and flange sections, laying the foundation for subsequent integrated molding. It should be noted that, compared to the seamless laying of the entire structure, this invention only thickens the outer layer and does not add prepreg in the middle, reducing material usage and weight. In addition, the two ends are locally thickened and extend to the flange, providing strength assurance for the flange frame in the later stage, while ensuring the connection strength between the flange and the pipe section.

[0033] Furthermore, in step 1), when laying the stop ring, the mold has corresponding grooves. The grooves are located at both ends of the mold near the flange position. The carbon fiber prepreg is laid in the grooves until the outer diameter of the stop ring is equal to the outer diameter of the mold.

[0034] This design ensures the reliability of the connection between the stop ring and the drive shaft, making the pipe section flat from the flange during installation and further guaranteeing strength.

[0035] Furthermore, in step 2), during the laying process, the material is laid layer by layer, diagonally from the flange section on one side of the mold through the round pipe section to the flange section on the other side. After each layer is laid, a gap will be formed on the flange sections on both sides, which is then filled with carbon fiber prepreg. After each layer is laid, the next layer of prepreg is laid at a distance from the previous layer, so that the gaps in the flange sections are staggered.

[0036] It should be noted that, as Figure 3 As shown, due to the diagonal laying, the first layer of prepreg will form a first slit when it is laid to the flange. This slit area is then filled with prepreg before laying the second layer. If the second layer is laid directly, it will overlap with the first slit, compromising the strength of the overlapping area. Therefore, by staggering the laying by a certain distance, the slit areas on the flange are also staggered. The final laying diagram of the first, second, and third layers of prepreg is shown below. Figure 3 As shown, the first, second, and third shear cuts on the flange are as follows: Figure 4 As shown, the distribution is uniform, thus ensuring the strength of the flange area.

[0037] Furthermore, in step 3), during the application, the prepreg is applied layer by layer, diagonally along the round pipe section of the mold to the flange section. After each layer is applied, a gap will be formed on the flange section, which is then filled with carbon fiber prepreg. After each layer is applied, the next layer of prepreg is applied at a distance from the previous layer, so that the gaps in the flange section are staggered.

[0038] This part follows the same principle as the tiling process and will not be repeated here.

[0039] Furthermore, it also includes laying carbon fiber prepreg in the middle of the central pipe section for dynamic balancing and molding.

[0040] It should be noted that since the drive shaft is always in a rotating state, it is necessary to perform dynamic balancing tests on the drive shaft. By designing a dynamic balancing mold repair area, the original drive shaft body will not be affected when performing dynamic balancing mold repair.

[0041] Specifically, after the paving is completed, the entire assembly is sent into an autoclave for curing. After demolding, an integrated composite material drive shaft is obtained. Since the autoclave curing process is a mature process, it will not be described in detail in this embodiment. The core inventive point of this invention is the specific operation process of the paving process.

[0042] The transmission shaft of the present invention will be analyzed below using specific finite element analysis.

[0043] For the drive shaft structure, finite element modeling and analysis were performed based on the actual dimensions, using the nonlinear finite element calculation software ABAQUS.

[0044] like Figure 5-6 As shown, after loading based on the design torque and safety factor, the calculated torque is 20000 N·m. The calculation results show that the maximum stress of the drive shaft is 509.3 MPa, located in the uniform thickness region of the drive shaft tube section, while the overall structural stress of the remaining parts is 339.8 MPa. The maximum tensile strain is approximately 3457 με, the maximum compressive strain is approximately 3490 με, and the interlaminar strain is 4639 με. According to the requirements of the load condition parameters, the buckling of the drive shaft under torque condition is calculated, and the first-order eigenvalue of the buckling analysis is 1.9. Subsequently, the static strength of the integrated drive shaft structure is verified through experiments. The drive shaft is tested according to the test loading table and loaded until failure.

[0045] Test loading table Duration 5min destroy Non-destructive Non-destructive destroy Note: The loading rate is 1000 N·m.

[0046] The test failure load is 3-4 times the design load. This meets the requirements.

[0047] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A process for laying an integrated composite material drive shaft, the integrated composite material drive shaft comprising a hollow tube, flanges at both ends of the hollow tube, the hollow tube comprising a middle section and two end sections, the middle section and the two end sections being of equal thickness, the thickness of the end sections being greater than that of the middle section, the thickness of the end sections being the same as that of the flanges, and stop rings being provided at the openings of the end sections, the hollow tube, flanges, and stop rings being integrally laid and formed using carbon fiber material, the transition between the middle section and the two end sections using a diameter change transition, and a dynamic balancing molding area being provided in the middle of the middle section, characterized in that... Includes the following steps: Step 1) Laying the stop ring: Lay the carbon fiber prepreg on the mold corresponding to the stop ring position. When laying the stop ring, the mold has a corresponding groove. The groove is set at both ends of the mold near the flange position. The carbon fiber prepreg is laid in the groove until the outer diameter of the stop ring is equal to the outer diameter of the mold. Step 2) Laying the inner layer of equal thickness: Lay the carbon fiber prepreg along the flange on one side of the mold through the pipe section to the flange on the other side to obtain the inner layer. When laying in Step 2), lay the layers one by one, diagonally from the flange section on one side of the mold through the round pipe section to the flange section on the other side. After each layer is laid, a gap will be formed on the flange sections on both sides. Fill the gap with carbon fiber prepreg. After each layer is laid, the next layer of prepreg is laid at a distance away from the previous layer of prepreg so that the gaps in the flange sections are staggered. Step 3) Laying the outer thickened area: On the inner surface, carbon fiber prepreg is laid along the positions of the two pipe sections to the flange head to obtain complete two pipe sections and flanges.

2. The laying process of an integrated composite material drive shaft according to claim 1, characterized in that, Step 3) When laying, lay the material layer by layer, diagonally along the round pipe section of the mold to the flange section. After each layer is laid, a gap will be formed on the flange section, which will be filled with carbon fiber prepreg.

3. The laying process of an integrated composite material drive shaft according to claim 2, characterized in that, After each layer is laid, the next layer of prepreg is laid at a distance from the previous layer, so that the gaps in the flange sections are staggered.

4. The laying process of an integrated composite material drive shaft according to claim 1, characterized in that, It also includes laying carbon fiber prepreg in the middle of the central pipe section for dynamic balancing and molding.

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