Knitting method for joint of three-dimensional woven annular preform
By designing a three-dimensional woven annular prefabricated joint weaving method with different weft paths, the problem of the inaccurate determination of connection performance in the prior art is solved, and precise control of the performance of connection and improvement of production efficiency is achieved.
Patent Information
- Application Number
- CN202510318638.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-18
- Publication Date
- 2025-06-27
AI Technical Summary
The connection performance at the connections of the existing three-dimensional woven annular prefabricated body cannot be accurately determined, and it is difficult to meet the complex load requirements and lightweight and high-performance design requirements.
Using a weaving method at the connection of a three-dimensional woven annular prefabricated body, different weft guide paths are designed to change the performance of the connection, ensuring the path and number of intersection points of the weft yarn across the layer connection at the front and back sides.
It realizes accurate control of the performance of the three-dimensional woven annular prefabricated body connection, meets the needs of the connections of different annular samples, and improves production quality and efficiency.
Smart Images
Figure CN120211010A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of three-dimensional weaving of composite materials, and specifically relates to a weaving method for the joint of a three-dimensional woven annular preform. Background Art
[0002] With the urgent need for the integrated forming of lightweight structural parts in the fields of aerospace and rail transit, etc., annular structural parts, as key load-bearing components of various aerospace vehicles and rail transit tools, are becoming increasingly important.
[0003] Such structural parts not only need to meet complex load requirements, but also take into account the design requirements of lightweight and high performance. At present, traditional processes are mainly based on laying and winding, and there are obvious limitations in the interlayer performance in the thickness direction. In contrast, carbon fiber three-dimensional fabric integrated forming components can not only achieve the integrity and lightweight of the structure, but also significantly improve the strength by optimizing the fabric structure.
[0004] Three-dimensional weaving, with its high weaving efficiency and forming quality, is one of the important forming methods of three-dimensional fabrics at present. Shuttle three-dimensional weaving equipment forms annular fabrics usually based on the "flattening - weaving - restoring" process for integrated forming, and preforms with different structures and strengths can be formed by designing different process parameters. The joint of the annular sample woven by "flattening - weaving - restoring" has a different overall tissue structure from the rest, and its specific performance needs to be focused on. However, the existing connection performance of the joint cannot be accurately determined. Summary of the Invention
[0005] Object of the Invention: Aiming at the above disadvantages, the present invention provides a weaving method for the joint of a three-dimensional woven annular preform that can accurately obtain the required performance of the joint.
[0006] Technical Solution: To solve the above problems, the present invention adopts a weaving method for the joint of a three-dimensional woven annular preform, including the following steps:
[0007] (1) Determine the thickness of the flattened and woven annular preform, so as to determine the number of weft layers n;
[0008] (2) The flattened woven annular preform includes a front side and a back side connected end to end. Determine the required performance at the connection of the front side and the back side, and determine the path of the weft yarn cross-layer connection at the connection of the front side and the back side according to the required performance: The front side includes a first front connection and a second front connection connected to the back side, and the back side includes a first back connection and a second back connection connected to the front side. The first front connection, the second front connection, the first back connection, and the second back connection each include n layers of weft yarns, and the n layers of weft yarns at the first front connection are respectively connected to the n layers of weft yarns at the first back connection in one-to-one correspondence. The n layers of weft yarns at the second front connection are respectively connected to the n layers of weft yarns at the second back connection in one-to-one correspondence. The i-th layer at the first front connection and the i-th layer at the second front connection are the same layer, and the i-th layer at the first back connection and the i-th layer at the second back connection are the same layer, and one weft yarn passes through all layers of the front side and the back side; Determine the number of intersections of the cross-layer connection of each layer of weft yarn at the connection of the front side and the back side according to the required performance, so as to determine the weft insertion path of the weft yarn;
[0009] (3) Determine the weft insertion order according to the determined weft insertion path of the weft yarn;
[0010] (4) Determine the serial number of the warp beam that needs to be lifted when each weft yarn is introduced according to the weft insertion order, and finally draw the corresponding woven pattern drawing for weaving.
[0011] Further, in the step (2), the n layers of weft yarns at the first front connection are respectively connected to the n layers of weft yarns at the first back connection in one-to-one correspondence. The n layers of weft yarns at the second front connection are respectively connected to the n layers of weft yarns at the second back connection in one-to-one correspondence, and one weft yarn passes through all layers of the front side and the back side; Specifically:
[0012] Taking the a-th layer at the first front connection as the starting point of the weft insertion path, the weft yarn of the a-th layer at the first front connection is connected to the i-th 21 layer of weft yarn at the first back connection, and the i-th 21 layer of weft yarn at the second back connection is connected to the i-th 11 layer of weft yarn at the second front connection, and i 11 ≠a; The i-th 11 layer of weft yarn at the first front connection is connected to the i-th 22 layer of weft yarn at the first back connection, and i 22 ≠i 21 , and the i-th 22 layer of weft yarn at the second back connection is connected to the i-th 12 layer of weft yarn at the second front connection, and i 12 ≠a≠i 11 ; The i-th 12 layer of weft yarn at the first front connection is connected to the i-th layer of weft yarn at the first back connection23 The i-th layer weft yarns at the second connection on the back side are connected to the i-th layer weft yarns at the second connection on the front side, and i 23 ≠i 22 ≠i 21 , the i-th layer weft yarns at the second connection on the back side are connected to the i-th layer weft yarns at the second connection on the front side, and i 23 the i-th layer weft yarns at the second connection on the back side are connected to the i-th layer weft yarns at the second connection on the front side, and i 13 the i-th layer weft yarns at the second connection on the back side are connected to the i-th layer weft yarns at the second connection on the front side, and i 13 ≠a≠i 11 ≠
[0013] i 12 ; and so on, until the i-th layer weft yarns at the first connection on the front side are connected to the i-th layer weft yarns at the first connection on the back side, and i 1n-1 the i-th layer weft yarns at the first connection on the front side are connected to the i-th layer weft yarns at the first connection on the back side, and i 2n-1 the i-th layer weft yarns at the first connection on the front side are connected to the i-th layer weft yarns at the first connection on the back side, and i 2n-1 ≠i 2n-2 ≠…≠i 23 ≠i 22 ≠i 21 , the i-th layer weft yarns at the second connection on the back side are connected to the i-th layer weft yarns at the second connection on the front side, and i 2n-1 the i-th layer weft yarns at the second connection on the back side are connected to the i-th layer weft yarns at the second connection on the front side, and i 1n-1 the i-th layer weft yarns at the second connection on the back side are connected to the i-th layer weft yarns at the second connection on the front side, and i 1n-1 ≠1≠i 11 ≠i 12 …≠i 1n-2 ; the i-th layer weft yarns at the first connection on the front side are connected to the i-th layer weft yarns at the first connection on the back side, and i 1n the i-th layer weft yarns at the first connection on the front side are connected to the i-th layer weft yarns at the first connection on the back side, and i 2n the i-th layer weft yarns at the first connection on the front side are connected to the i-th layer weft yarns at the first connection on the back side, and i 2n ≠i 2n-1 ≠…≠i 23 ≠i 22 ≠i 21 , the i-th layer weft yarns at the second connection on the back side are connected to the i-th layer weft yarns at the second connection on the front side, and i 2n the i-th layer weft yarns at the second connection on the back side are connected to the i-th layer weft yarns at the second connection on the front side, and i 1n the i-th layer weft yarns at the second connection on the back side are connected to the i-th layer weft yarns at the second connection on the front side, and i 1n =a.
[0014] Furthermore, a complete passage of a weft yarn through all layers on the front side and the back side once is defined as a stack. The weft yarn insertion paths at the first connection on the front side and the first connection on the back side of the m-th stack are centrosymmetric about the central axis of the annular preform with respect to the weft yarn insertion paths at the second connection on the front side and the second connection on the back side of the adjacent (m + 1)-th stack; the weft yarn insertion paths at the second connection on the front side and the second connection on the back side of the m-th stack are centrosymmetric about the central axis of the annular preform with respect to the weft yarn insertion paths at the first connection on the front side and the first connection on the back side of the adjacent (m + 1)-th stack.
[0015] Further, in the same stack, the weft yarn cross-layer connection relationship between the first front connection and the first back connection is symmetric with respect to the central axis of the annular preform, that is, when the i-th layer at the first front connection is connected to the j-th layer at the first back connection, the i-th layer at the second front connection is connected to the (j + 1)-th or (j - 1)-th layer at the second back connection.
[0016] Further, the weft insertion paths where there are no intersections between the cross-layers of the weft yarns at the front side and the back side connections include:
[0017] Taking the n-th layer at the first front connection as the starting point of the weft insertion path, the weft yarn of the n-th layer at the first front connection is connected to the weft yarn of the n-th layer at the first back connection, the weft yarn of the n-th layer at the second back connection is connected to the weft yarn of the (n - 1)-th layer at the second front connection, and n - 1 ≠ 0; the weft yarn of the (n - 1)-th layer at the first front connection is connected to the weft yarn of the (n - 1)-th layer at the first back connection, the weft yarn of the (n - 1)-th layer at the second back connection is connected to the weft yarn of the (n - 2)-th layer at the second front connection; and so on, until the weft yarn of the 1st layer at the first front connection is connected to the weft yarn of the 1st layer at the first back connection, and the weft yarn of the 1st layer at the second back connection is connected to the weft yarn of the second front connection of the next stack;
[0018] Taking the 1st layer at the first front connection as the starting point of the weft insertion path, the weft yarn of the 1st layer at the first front connection is connected to the weft yarn of the 1st layer at the first back connection, the weft yarn of the 1st layer at the second back connection is connected to the weft yarn of the 2nd layer at the second front connection, the weft yarn of the 2nd layer at the first front connection is connected to the weft yarn of the 2nd layer at the second back connection, the weft yarn of the 2nd layer at the second back connection is connected to the weft yarn of the 3rd layer at the second front connection, and so on, until the weft yarn of the n-th layer at the first front connection is connected to the weft yarn of the n-th layer at the first back connection, and the weft yarn of the n-th layer at the second back connection is connected to the weft yarn of the second front connection of the next stack.
[0019] The present invention also adopts a preparation method of a three-dimensional woven annular preform based on the weaving method at the connection of the above three-dimensional woven annular preform, including the following steps:
[0020] (1) Determine the thickness, diameter, length and connection performance of the annular preform;
[0021] (2) Determine the number of weft yarn layers according to the thickness of the annular preform, determine the number of warp yarn layers according to the diameter of the annular preform, determine the total number of stacks according to the length of the annular preform, and determine the weft insertion order of the weft yarns according to the connection performance of the annular preform;
[0022] (3) Draw the corresponding woven pattern layout according to the determined data and perform flattened weaving through a three-dimensional loom;
[0023] (4) Restore the flattened and woven annular preform to its original annular shape.
[0024] The present invention also adopts a three-dimensional woven annular preform obtained by weaving using the above-mentioned preparation method of a three-dimensional woven annular preform.
[0025] Beneficial effects: Compared with the prior art, the significant advantage of the present invention is that different weft insertion paths have different effects on the performance of the joints of the three-dimensional woven annular preform. Design the corresponding weft insertion paths for the weft yarns crossing layers at the joints according to the required joint performance, and quickly optimize the process parameters to meet the requirements of different annular sample joints, improving the production quality and efficiency. Description of the Drawings
[0026] Figure 1 It is a schematic flow chart of the weaving method at the joint of the present invention.
[0027] Figure 2 It is a schematic connection diagram of the weft yarns crossing layers and connecting at a certain pile of joints in the present invention.
[0028] Figure 3 It is a schematic diagram of the weft yarns crossing layers and connecting across piles during flattened weaving in the present invention.
[0029] Figure 4 It is a schematic diagram of the weft insertion sequence of the weft yarns crossing layers in the present invention.
[0030] Figure 5 It is the weft insertion and weaving pattern diagram of the present invention.
[0031] Figure 6 It is the top view and three-dimensional schematic diagram of the annular preform at a single intersection of the joints of a single pile of weft yarns in the present invention. Detailed Embodiments
[0032] As Figure 1 shown, a weaving method for the joints of a three-dimensional woven annular preform in this embodiment includes the following steps:
[0033] (1) Determine the thickness of the flattened and woven annular preform, and thus determine the number of weft yarn layers n; in this embodiment, an annular preform with a wall thickness of 6 layers of weft yarns is taken as an example;
[0034] (2) Different weft insertion paths, i.e., different weft insertion sequences, are the key to affecting the weft structure at the connection. To ensure the symmetry of the connection on both sides of the annular preform, the annular preform is represented by the front side and the back side. The flattened woven annular preform includes a front side and a back side connected end to end. Determine the required performance at the connection of the front side and the back side. According to the required performance, determine the path of the weft yarn cross-layer connection at the connection of the front side and the back side. By designing different weft insertion paths, the performance at the connection can be changed. One weft yarn passing through all layers of the front side and the back side completely once is a stack. Each stack has a total of 20 warp yarns and 12 weft yarns. After completing the weft insertion of one layer, another layer of weft insertion needs to be carried out. The yarn connecting these two layers of weft yarns is the weft yarn at the connection.
[0035] The front side includes a front first connection and a front second connection connected to the back side. The back side includes a back first connection and a back second connection connected to the front side. In this embodiment, the front first connection, the front second connection, the back first connection, and the back second connection all include 6 layers of weft yarns. And the 6 layers of weft yarns at the front first connection are respectively connected to the 6 layers of weft yarns at the back first connection one by one. The 6 layers of weft yarns at the front second connection are respectively connected to the 6 layers of weft yarns at the back second connection one by one. As Figure 2 shown, in the drawings of this embodiment, the number of layers at the first connection of the front side and the back side and the second connection of the front side and the back side are represented by 1 to 12 layers. Among them, layers 1-6 are the first and second connections of the front side, and layers 7-12 are the first and second connections of the back side; among them, the solid line represents the weft yarn connected between the front first connection and the back first connection, the dotted line represents the weft yarn connected between the front second connection and the back second connection, the green solid line represents the starting weft yarn layer of the weft yarn at a certain stack connection, and the brown dotted line represents the weft yarn for changing stacks, that is, the 6th layer of weft yarn connecting the front first connection of the next stack. The arrow indicates the direction of the weft yarn cross-layer. The i-th layer at the front first connection and the i-th layer at the front second connection are the same layer. The i-th layer at the back first connection and the i-th layer at the back second connection are the same layer. And one weft yarn passes through all layers of the front side and the back side to ensure the integrity of the structure. All weft yarns need to connect the upper and lower layers to enhance the interlayer bonding force of the preform; determine the number of intersection points of the cross-layer connection of each layer of weft yarn at the connection of the front side and the back side according to the required performance, so as to determine the weft insertion path of the weft yarn.
[0036] In flattened weaving, the 6 layers of weft yarns on the front side and the 6 layers of weft yarns on the back side are combined to form 12 layers of weft yarns. As Figure 3 shown is the weft yarn layout at the connection during flattened weaving, where "×" represents the vertical cross-section of the weft yarn entering (representing the weft yarn on the back side), "·" represents the vertical cross-section of the weft yarn exiting (representing the weft yarn on the front side), and the solid line, dotted line, green solid line, and brown dotted line are the same as Figure 2It has the same meaning as above. The orange dashed box represents a complete circular weft insertion cycle. This figure clearly reflects the cross-layer weft insertion sequence, weft insertion pile change, and the complete weft insertion cycle of the circular weft insertion path, which is convenient for the design and inspection of the pile-changing weft yarn; the weft insertion path should be able to cycle quickly to improve the weaving efficiency. For the first pile, the weft insertion path of the second connection at the front and the second connection at the back is that the 5th layer is connected to the 7th layer. For the second pile, the weft insertion path of the first connection at the front and the first connection at the back is that the 6th layer is connected to the 8th layer. The two connection paths are centrosymmetric about the central axis of the circular preform.
[0037] Specifically: Taking the ath layer at the first connection at the front as the starting point of the weft insertion path, the weft yarn of the ath layer at the first connection at the front is connected to the ith 21 layer weft yarn at the first connection at the back, and the ith 21 layer weft yarn at the second connection at the back is connected to the ith 11 layer weft yarn at the second connection at the front, and i 11 ≠a; the ith 11 layer weft yarn at the first connection at the front is connected to the ith 22 layer weft yarn at the first connection at the back, and i 22 ≠i 21 ; the ith 22 layer weft yarn at the second connection at the back is connected to the ith 12 layer weft yarn at the second connection at the front, and i 12 ≠a≠i 11 ; the ith 12 layer weft yarn at the first connection at the front is connected to the ith 23 layer weft yarn at the first connection at the back, and i 23 ≠i 22 ≠i 21 ; the ith 23 layer weft yarn at the second connection at the back is connected to the ith 13 layer weft yarn at the second connection at the front, and i 13 ≠a≠i 11 ≠i 12 ; and so on, until the ith 1n-1 layer weft yarn at the first connection at the front is connected to the ith 2n-1 layer weft yarn at the first connection at the back, and i 2n-1 ≠i 2n-2 ≠…≠i 23 ≠i 22 ≠i 21 ; the ith 2n-1 layer weft yarn at the second connection at the back is connected to the ith 1n-1 layer weft yarn at the second connection at the front, and i 1n-1 ≠1≠i 11 ≠i 12 …≠i 1n-2; the i-th layer of weft yarn at the first front connection is connected to the i-th layer of weft yarn at the first back connection, and i 1n ≠ i 2n ≠…≠ i 2n ≠ i 2n-1 ≠ i 23 ≠ i 22 ≠ i 21 , the i-th layer of weft yarn at the second back connection is connected to the i-th layer of weft yarn at the second front connection, and i 2n =a. Taking the a-th layer at the first front connection as the starting point of the weft insertion path as an example, the connection methods of the a-th layer at the second front connection, the first back connection, and the second back connection are the same as the starting point of the weft insertion path. 1n 1n A complete passage of a weft yarn through all layers on the front side and the back side once is regarded as a pile. The weft insertion paths of the weft yarns at the first front connection and the first back connection of the m-th pile are centrosymmetric with respect to the central axis of the annular preform to the weft insertion paths of the weft yarns at the second front connection and the second back connection of the adjacent m + 1-th pile; the weft insertion paths of the weft yarns at the second front connection and the second back connection of the m-th pile are centrosymmetric with respect to the central axis of the annular preform to the weft insertion paths of the weft yarns at the first front connection and the first back connection of the adjacent m + 1-th pile. In the same pile, the cross-layer connection relationship of the weft yarns at the first front connection and the first back connection is symmetric with respect to the central axis of the annular preform to the cross-layer connection relationship of the weft yarns at the second front connection and the second back connection, that is, when the i-th layer at the first front connection is connected to the j-th layer at the first back connection, the i-th layer at the second front connection is connected to the j + 1 or j - 1-th layer at the second back connection. To ensure the uniformity of the preform. As
[0038] shown, when the 5th layer at the first front connection is connected to the 8th layer at the first back connection, the 5th layer at the second front connection is connected to the 7th layer at the second back connection. Since the starting point is the 6th layer at the first front connection and the 6th layer at the second front connection is connected to the previous pile, for the second front connection, the 5th layer is the last layer of this pile's connection, and the path connecting to the first layer, the 7th layer, at the second back connection; and the last layer, the 6th layer, at the first front connection and the path connecting to the first layer, the 7th layer, at the first back connection are symmetric to ensure the uniformity of the preform. As Figure 2 Figure 2 shown is the weft insertion path where there is no intersection between the layers of the weft yarns at the connections on the front side and the back side. The paths are relatively parallel, the structure ductility at the connection is better, but the impact resistance is poor, and cracks are easy to expand; increasing the intersection points of the weft yarns across layers at the connection (as Figure 6 shown, such as the 6th layer at the first front connection is connected to the 8th layer at the first back connection, and the 5th layer at the first front connection is connected to the 7th layer at the first back connection), increasing the external impact resistance at the connection, then the ductility at the connection becomes worse.
[0039] (3) Determine the weft insertion order according to the determined weft insertion path of the weft yarn, as Figure 4 shown, the numbers in the circles are the order in which the weft yarns are lifted;
[0040] (4) Determine the serial numbers of the warp beam frames that need to be lifted when each weft yarn is introduced according to the weft insertion order, and finally draw the corresponding woven pattern drawing for weaving, as Figure 5 shown.
Claims
1. A method for weaving a connection of a three-dimensional woven annular preform, characterized in that: The following steps are involved: (1) Determine the thickness of the flattened woven annular preform, thereby determining the number of weft yarn layers n; (2) The flattened woven annular preform includes a front side and a back side connected end to end, and the required performance of the connection between the front side and the back side is determined. The path of the weft yarn cross-layer connection at the connection between the front side and the back side is determined according to the required performance: the front side includes a first front connection and a second front connection connected to the back side, and the back side includes a first back connection and a second back connection connected to the front side. The first front connection, the second front connection, the first back connection, and the second back connection all include n layers of weft yarns, and the n layers of weft yarns at the first front connection are respectively connected one-to-one with the n layers of weft yarns at the first back connection, and the n layers of weft yarns at the second front connection are respectively connected one-to-one with the n layers of weft yarns connected to the second back connection. The i-th layer at the first front connection is the same layer as the i-th layer at the second front connection, and the i-th layer at the first back connection is the same layer as the i-th layer at the second back connection, and one weft yarn passes through all the layers of the front side and the back side; the number of intersections of the weft yarns of each layer cross-layer connection at the connection between the front side and the back side is determined according to the required performance, thereby determining the weft insertion path of the weft yarn; (3) determining a weft insertion sequence according to the determined weft insertion path of the weft yarn; (4) According to the weft insertion sequence, the warp frame number that needs to be lifted when each weft yarn is introduced is determined, and finally the corresponding woven pattern is drawn for weaving.
2. The weaving method for the connection of a three-dimensional woven annular preform according to claim 1, characterized in that: In the step (2), the n layers of weft yarns at the first connection on the front side are respectively connected to the n layers of weft yarns at the first connection on the back side in a one-to-one correspondence, and the n layers of weft yarns at the second connection on the front side are respectively connected to the n layers of weft yarns connected to the second connection on the back side in a one-to-one correspondence, and one weft yarn passes through all layers on the front side and the back side; specifically: The ath layer at the first connection on the front side is taken as the starting point of the weft insertion path. The ath layer weft yarn at the first connection on the front side and the ith layer weft yarn at the first connection on the back side are connected. 21 Layer weft connection, the second connection on the back side 21 The i-th connection between the layer of weft yarn and the second connection on the front side 11 Layers of weft yarns are connected, and i 11 ≠a; the first connection point on the front side i 11 The first connection between the layer of weft yarn and the back 22 Layers of weft yarns are connected, and i 22 ≠i 21 , the i-th connection at the second connection on the back 22 The i-th connection between the layer of weft yarn and the second connection on the front side 12 Layers of weft yarns are connected, and i 12 ≠a≠i 11 ; The first connection at the front 12 The first connection between the layer of weft yarn and the back 23 Layers of weft yarns are connected, and i 23 ≠i 22 ≠i 21 , the i-th connection at the second connection on the back 23 The i-th connection between the layer of weft yarn and the second connection on the front side 13 Layers of weft yarns are connected, and i 13 ≠a≠i 11 ≠i 12 ; and so on, until the first connection on the front side, the i-th 1n-1 The first connection between the layer of weft yarn and the back 2n-1 Layers of weft yarns are connected, and i 2n-1 ≠i 2n-2 ≠…≠i 23 ≠i 22 ≠i 21 , the i-th connection at the second connection on the back 2n-1 The i-th connection between the layer of weft yarn and the second connection on the front side 1n-1 Layers of weft yarns are connected, and i 1n-1 ≠1≠i 11 ≠i 12 …≠i 1n-2 ; The first connection at the front 1n The first connection between the layer of weft yarn and the back 2n Layers of weft yarns are connected, and i 2n ≠i 2n-1 ≠…≠i 23 ≠i 22 ≠i 21 , the i-th connection at the second connection on the back 2n The i-th connection between the layer of weft yarn and the second connection on the front side 1n Layers of weft yarns are connected, and i 1n =a.
3. The weaving method of the connection of the three-dimensional woven annular preform according to claim 2, characterized in that: A weft yarn passes through all the layers on the front side and the back side once completely to form a pile, and the weft yarn insertion path at the first connection on the front side and the first connection on the back side of the mth pile is symmetrical with the weft yarn insertion path at the second connection on the front side and the second connection on the back side of the adjacent m+1th pile along the central axis of the annular preform; the weft yarn insertion path at the second connection on the front side and the second connection on the back side of the mth pile is symmetrical with the weft yarn insertion path at the first connection on the front side and the first connection on the back side of the adjacent m+1th pile along the central axis of the annular preform.
4. The weaving method for the connection of a three-dimensional woven annular preform according to claim 3, characterized in that: In the same pile, the weft yarn cross-layer connection relationship between the first connection on the front side and the first connection on the back side is symmetrical with the weft yarn cross-layer connection relationship between the second connection on the front side and the second connection on the back side along the central axis of the annular preform, that is, when the i-th layer at the first connection on the front side is connected to the j-th layer at the first connection on the back side, the i-th layer at the second connection on the front side is connected to the j+1 or j-1-th layer at the second connection on the back side.
5. The weaving method for the connection of a three-dimensional woven annular preform according to claim 4, characterized in that: The weft insertion paths without intersections between the weft yarns of each layer at the connection between the front side and the back side include: Taking the nth layer at the first connection of the front side as the starting point of the weft insertion path, the nth layer of weft yarn at the first connection of the front side is connected to the nth layer of weft yarn at the first connection of the back side, and the nth layer of weft yarn at the second connection of the back side is connected to the n-1th layer of weft yarn at the second connection of the front side, and n-1≠0; the n-1th layer of weft yarn at the first connection of the front side is connected to the n-1th layer of weft yarn at the first connection of the back side, and the n-1th layer of weft yarn at the second connection of the back side is connected to the n-2th layer of weft yarn at the second connection of the front side; and so on, until the 1st layer of weft yarn at the first connection of the front side is connected to the 1st layer of weft yarn at the first connection of the back side, and the 1st layer of weft yarn at the second connection of the back side is connected to the next pile of weft yarns at the second connection of the front side; Taking the first layer at the first connection on the front side as the starting point of the weft insertion path, the first layer of weft yarn at the first connection on the front side is connected to the first layer of weft yarn at the first connection on the back side, the first layer of weft yarn at the second connection on the back side is connected to the second layer of weft yarn at the second connection on the front side, the second layer of weft yarn at the second connection on the back side is connected to the third layer of weft yarn at the second connection on the front side, and so on, until the nth layer of weft yarn at the first connection on the front side is connected to the nth layer of weft yarn at the first connection on the back side, and the nth layer of weft yarn at the second connection on the back side is connected to the next pile of weft yarns at the second connection on the front side.
6. A method for preparing a three-dimensional woven annular preform using the weaving method for the connection of the three-dimensional woven annular preform according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Determine the thickness, diameter, length and joint performance of the annular preform; (2) determining the number of weft yarn layers according to the thickness of the annular preform, determining the number of warp yarn layers according to the diameter of the annular preform, determining the total number of stacks according to the length of the annular preform, and determining the weft insertion sequence according to the performance of the connection of the annular preform; (3) drawing a corresponding woven pattern according to the determined data and flattening and weaving it through a three-dimensional loom; (4) The flattened woven annular preform is restored into an annular shape.
7. A three-dimensional woven annular preform, characterized in that: The three-dimensional woven annular preform is woven by the preparation method of the three-dimensional woven annular preform described in claim 6.