A preform of a variable-thickness coupling structure with adjustable fiber orientation and a preparation method thereof

Abstract

The present invention relates to a variable-thickness coupled structure preform with adjustable fiber orientation, which comprises two parts: a high-thickness fabric area and a thickness-reducing fabric area. The high-thickness fabric area is divided into a flat fabric area and a variable-thickness fabric area; both the high-thickness fabric area and the thickness-reducing fabric area contain warp yarns, weft yarns and warp-lining yarns; the thickness-reducing fabric area further contains diagonal yarns; the warp yarns and the warp-lining yarns are arranged along the length direction of the preform, and are connected to the thickness-reducing fabric area after passing through the flat fabric area and the variable-thickness fabric area; in the variable-thickness fabric area, the thickness of the fabric is continuously reduced along the length direction of the preform by reducing the number of inner-layer weft yarns and cutting the corresponding warp yarns and warp-lining yarns; part of the remaining warp-lining yarns in the variable-thickness fabric area continue to be used as warp-lining yarns after entering the thickness-reducing fabric area, and the rest are deflected in-plane, thereby being converted into diagonal yarns; the remaining yarns are bundled together by the warp yarns, thereby integrally weaving into a coupled structure preform. The present invention comprehensively balances the overall load-bearing capacity of the blade and further improves the service performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of aero-engine fan blade weaving, and particularly relates to a variable-thickness coupling structure preform with adjustable fiber orientation and a preparation method thereof. Background Technique

[0002] With the rapid development of world aviation power technology, high-bypass ratio turbofan engines are continuously moving forward towards high-performance directions such as low fuel consumption, low emissions, low noise, easy maintenance, high reliability, and long life. Based on the above performance requirements, the use of fiber-reinforced composite materials provides an effective solution for the lightweight design of aero-engine components. It can replace traditional lightweight metal materials without changing the original structural layout of the aero-engine and ensuring sufficient strength and safety, so as to further improve the comprehensive performance of the engine. Compared with traditional two-dimensional laminated composites, three-dimensional woven composites have excellent delamination resistance due to the existence of binder warp yarn systems in the thickness direction to bundle and connect the remaining yarn systems. Moreover, the preform structure has strong designability, can be near-net shaped, has a simple manufacturing process, and a low manufacturing cost, and has become an ideal choice for aero-engine fan blades.

[0003] Uniform variable thickness is one of the difficulties in the development of three-dimensional woven preforms for fan blades. Patent US7101154B2 introduces a method for integrally weaving a variable-thickness three-dimensional woven preform for fan blades on an automatic jacquard loom, and realizes the continuous and uniform variable thickness of the preform by gradually changing the weft yarn density, the number of warp yarns, etc. However, the in-plane of the preform only contains X-direction and Y-direction fibers, resulting in poor in-plane isotropy. When subjected to external impacts, the energy dissipation ability is poor, especially in the blade body part that is easily impacted by foreign objects (such as birds, sand, ice, etc.), resulting in a certain degree of weakening of its impact resistance. In the journal literature "Low-Velocity Impact Mechanical Properties of Multiaxial Three-Dimensional Woven Composites", the author uses a drop hammer impact device to experimentally analyze the low-velocity impact mechanical properties of multiaxial three-dimensional woven composites containing diagonal yarns and three-dimensional orthogonal woven composites without diagonal yarns. The results show that the introduction of diagonal yarns makes the multiaxial three-dimensional woven composites have a higher ability to withstand low-velocity impact loads and better energy absorption performance.

[0004] To improve the impact resistance of fan blades, bias yarns can be introduced into the variable-thickness three-dimensional woven preforms for fan blades. However, in the journal literature "Tensile Properties of Multilayer Multi-directional Layered Three-dimensional Woven Composites", the authors designed and prepared three different structures of multilayer multi-directional layered three-dimensional woven composites and studied their tensile properties. The study pointed out that the content of bias yarns would have a significant impact on the tensile strength and tensile modulus of multilayer multi-directional layered three-dimensional woven composites. With the increase in the content of bias yarns, when stretching along the 0° direction, the tensile strength and tensile modulus decreased, while when stretching along the 90° direction, the opposite change law was shown. In addition, due to the fact that the blades work in an environment of centrifugal force, aerodynamic force and various impact loads for a long time and are in a complex stress state, high-cycle fatigue failure of the blades will occur, especially fatigue cracks are likely to occur and even fracture near the blade tenons. It can be seen that simply introducing bias yarns into the variable-thickness three-dimensional woven preforms for fan blades will cause a relative loss of the tensile strength of the blades, accelerate the growth of fatigue cracks near the blade tenons, and seriously threaten the service safety and structural reliability of aeroengines. Therefore, when introducing bias yarns into the blades, it is also necessary to comprehensively consider the different requirements of the impact resistance of the blade body part and the tensile properties of the blade tenons, and conduct differential design of the mechanical properties of the blade tenon part and the blade body part.

[0005] Patent CN116288877A introduces a preparation method for introducing bias yarns into a stiffened grooved three-dimensional woven preform. This preparation method is based on the multi-directional movement design of the yarn spindles of the existing three-dimensional woven preforms, and uses the yarn reservation process to achieve the overall weaving and forming, so that some yarns of the same yarn system are reserved and participate in the subsequent weaving in different regions, realizing the yarn transition in the corner region at the bottom of the fabric. However, the overall unified organizational structure form is adopted, and the bearing capacity of different regions has not changed. Therefore, it is not applicable to fan blades with different mechanical properties. So this method is difficult to be directly used for the preparation of variable-thickness three-dimensional woven preforms for fan blades, which limits its engineering application value. Therefore, the structure and preparation of fan blades need to be improved again. Summary of the Invention

[0006] The present invention provides a variable-thickness coupling structure preform with adjustable fiber orientation and its preparation method to solve the technical problems existing in the known technology, so that the overall bearing capacity of the blade is comprehensively balanced, the service performance is further improved, and the process is simplified at the same time.

[0007] The present invention includes the following technical solutions: A variable-thickness coupled structure preform with adjustable fiber orientation, comprising two parts: a high-thickness fabric area and a thickness-reducing fabric area, corresponding to the tenon part and the blade body part of the fan blade respectively. The high-thickness fabric area is divided into a flat fabric area and a variable-thickness fabric area; both the high-thickness fabric area and the thickness-reducing fabric area contain warp yarns, weft yarns and backing warp yarns; and the thickness-reducing fabric area further contains diagonal yarns, diagonal yarns; the warp yarns and backing warp yarns are along the length direction of the preform, and are connected to the thickness-reducing fabric area after passing through the variable-thickness fabric area from the flat fabric area; in the variable-thickness fabric area, the fabric thickness is continuously reduced along the length direction of the preform by reducing the number of inner-layer weft yarn layers and cutting the corresponding warp yarns and backing warp yarns; the remaining backing warp yarns in the variable-thickness fabric area continue to be used as backing warp yarns after entering the thickness-reducing fabric area, and the rest are deflected in-plane, thus being converted into the diagonal yarns of the thickness-reducing fabric area; the remaining yarns in the high-thickness fabric area and the thickness-reducing fabric area are bundled together by the warp yarns, thus integrally weaving into a coupled structure preform.

[0008] Further, among the remaining backing warp yarns in the variable-thickness fabric area, those close to the fabric surface and those close to the fabric center continue to be used as backing warp yarns, and some of the inner-layer backing warp yarns are deflected in-plane and converted into diagonal yarns. This is because the movement law of the backing warp yarns is the simplest, only remaining straight in the fabric length direction, and deflecting it in-plane is easier for actual machine operation.

[0009] Further, the inner-layer backing warp yarns in the thickness-reducing fabric area need to be selectively deflected in-plane (the deflection principle is to reasonably control the content, position and angle of the diagonal yarns, and specifically design according to the size and mechanical property requirements of the preform). After deflection, at least one group of diagonal yarns is included in the thickness direction of the preform, and each group is divided into +θ angle diagonal yarns and -θ angle diagonal yarns. The inclination angle of the diagonal yarns in the length direction of the preform is 30° - 60°; when the number of diagonal yarns in the preform is an even number of groups, different groups of diagonal yarns are symmetrically arranged and distributed between the preform layers. This not only ensures the volume content of the main load-bearing fibers in the length direction of the preform, thereby reducing the loss of tensile properties, but also achieves the purpose of improving the impact resistance.

[0010] Further, when two groups of diagonal yarns are included in the thickness direction of the preform, the two groups of diagonal yarns are symmetrically distributed in the position between the preform layers; when the inclination angle of the diagonal yarns is 45°, the impact resistance of the preform is the best.

[0011] Further, both the high-thickness fabric area and the thickness-reducing fabric area adopt a plain weave interlayer angle interlock structure as the basic tissue structure. The warp yarns bundle the remaining yarns together according to the movement law of the plain weave tissue between the fabric layers, thereby ensuring that the fabric can meet the process requirements of good deformation performance and shapeability for later composite processing.

[0012] A preparation method for a variable-thickness coupling structure preform with adjustable fiber orientation, comprising the following steps:

[0013] (1) Arrangement of main yarns: Warps and supplementary warps are initially arranged in the high-thickness fabric area; during the thickening process from the high-thickness fabric area to the thinning fabric area, the warps and supplementary warps are rearranged in the thickening fabric area; in the thickening fabric area, the fabric thickness is continuously reduced along the length direction of the preform by reducing the number of inner weft layers and cutting the corresponding warps and supplementary warps. After the thickening is completed, part of the remaining supplementary warps in the thickening fabric area continue to be used as supplementary warps after entering the thinning fabric area, and the rest are deflected in-plane, thus being converted into the diagonal yarns in the thinning fabric area; finally, the warps, supplementary warps, and diagonal yarns are rearranged in the thinning fabric area, and the edge yarns of the diagonal yarns are initially arranged in the thinning fabric area.

[0014] (2) Warp shedding motion: Complete the misalignment of the warp columns of the equipment according to the motion law of the warps in the plain interlayer angle interlock structure, driving the warps to form a warp shed.

[0015] (3) Introduction of diagonal yarns: During the weaving process of the high-thickness fabric area 1, this step can be skipped and the remaining steps can be carried out; during the weaving process of the thinning fabric area 2, this step must be completed before the remaining steps can be carried out, so the diagonal yarn 6 only moves in the thinning fabric area 2.

[0016] (4) Introduction of weft yarns: In the formed warp shed, the weft yarns are sequentially introduced into each warp shed by the weft yarn device.

[0017] (5) Pressing the weft yarns: The yarn pressing device is inserted between the columns of the warps, translated towards the cloth fell, and the weft yarns are beaten into the cloth fell, and then the yarn pressing device is removed.

[0018] (6) Repeat the above steps (2)-(5) until the target length of the fabric is reached, stop the fabric weaving, cut the yarns from the cloth fell, and finally obtain a variable-thickness coupling structure preform with adjustable fiber orientation.

[0019] Furthermore, in the step (1), the yarn bobbins of the warps are arranged on the warp guide bars, and the yarn bobbins in both the high-thickness fabric area and the thinning fabric area are arranged in a regular quadrilateral pattern; the edge yarns of the diagonal yarns are initially arranged in the thinning fabric area, and there is a guide yarn side bar for the diagonal yarns on each of the left and right sides of the thinning fabric area. One +θ angle diagonal yarn is arranged on the yarn bobbin of the left-edge yarn in the thinning fabric area; one -θ angle diagonal yarn is arranged on the yarn bobbin of the right-edge yarn in the thinning fabric area. The number of rows and columns of the main yarns can be specifically designed according to the external dimensions and weaving parameters of the prefabricated fabric for the fan blade.

[0020] Further, in the step (2), the shedding motion of the warp yarns includes the shedding motion in the high-thickness fabric area and the thickness-reducing fabric area. The motion directions of the warp yarns in the two areas are both parallel to the direction of the lining warp yarns in the preform. In addition, the lining warp yarn spindles in the flat fabric area remain stationary during the weaving process.

[0021] Further, in the step (3), adjacent diagonal yarn spindles are grouped into one set, and there are 2 sets in total in the thickness-reducing fabric area. The +θ-angle diagonal yarn spindles move one step to the right, the -θ-angle diagonal yarn spindles move one step to the left. The edge yarn spindles of the +θ-angle diagonal yarns move to the layer of the adjacent -θ-angle diagonal yarn spindles, and the edge yarn spindles of the -θ-angle diagonal yarns move to the layer of the adjacent +θ-angle diagonal yarn spindles. The number of positions where the diagonal yarn spindles (i.e., the original lining warp yarn spindles) move along the row direction can be adjusted according to the design, and the number of positions where the +θ-angle diagonal yarn spindles move along the row direction is the same as that of the -θ-angle diagonal yarn spindles moving along the row direction. The number of positions where the edge yarn spindles of the diagonal yarns move along the column direction is determined by the number of spaced layers between the same set of +θ-angle diagonal yarn layers and +θ-angle diagonal yarn layers, and can be adjusted according to the design.

[0022] Further, in the step (6), the target length of the fabric is set according to the needs of the user.

[0023] Further, the method for changing the angle θ of the diagonal yarn is to change the arrangement density of the warp yarns, lining warp yarns and weft yarns, or change the coordination of the stepping motion of the diagonal yarn and the insertion of the weft yarn, or use a combination of the above two methods. The change in the coordination of the stepping motion of the diagonal yarn and the insertion of the weft yarn means increasing the angle θ of the diagonal yarn by increasing the number of motion steps of the diagonal yarn, or increasing the angle θ of the diagonal yarn by reducing the number of times of inserting the weft yarn.

[0024] The advantages and positive effects of the present invention are as follows:

[0025] 1. At present, the variable-thickness three-dimensional woven preform for fan blades only contains X-direction and Y-direction fibers, with poor in-plane isotropy. When subjected to external impacts, the energy dissipation is poor, and the impact resistance needs to be improved. Introducing diagonal yarns into the variable-thickness three-dimensional woven preform can improve the impact resistance of the fan blades, but introducing diagonal yarns alone will cause a loss of the tensile strength of the blades. To solve this problem, the preform in the present invention designs the organizational structures without diagonal yarns and with diagonal yarns at the tenon and blade body positions respectively. By appropriately introducing diagonal yarns, the impact resistance of the blade body is improved, and the excessive loss of the strength of the blade body part is avoided. At the same time, the organizational structure without diagonal yarns is adopted to ensure the tensile properties of the blade tenon part and inhibit the initiation and propagation of fatigue cracks near the blade tenon. By coupling the two organizational structures together to form a variable-thickness three-dimensional woven preform, the mechanical property requirements of different positions are met respectively, and finally the overall bearing capacity of the blade is comprehensively balanced, and the overall performance of the blade is further improved at the same time.

[0026] 2. The present invention realizes that the thickness of the flat fabric area in the high-thickness fabric area continuously decreases along the length direction of the preform towards the thickness-reduced fabric area by reducing the number of inner yarns (specifically, reducing the number of inner weft yarn layers and cutting the corresponding warp yarns and backing warp yarns), which can cover the yarn breaks caused by reducing the yarns. This not only reduces the damage to the mechanical properties caused by yarn pulling and spreading, but also makes the fabric surface smoother and flatter.

[0027] 3. Based on the existing three-dimensional fabric weaving method, the present invention first adopts a conversion design method for adjusting the fiber orientation, so that the three-dimensional woven structure containing backing warp yarns in the high-thickness fabric area transitions into a three-dimensional woven structure containing inclined yarns in the thickness-reduced fabric area, and also couples the two organizational structures in the fan blade at the same time; both the high-thickness fabric area and the thickness-reduced fabric area adopt a plain weave interlayer angle interlock structure as the basic organizational structure, and all the yarns in the two parts are tied together by warp yarns to ensure that the preform can meet the good deformation performance and shapeability required for later composite processing.

[0028] 4. The previous weaving method based on the multi-directional movement of yarn spindles cannot be directly used for the preparation of a variable-thickness three-dimensional woven preform for a fan blade with a differential mechanical property design. In the preform preparation process adopted by the present invention, through the multi-directional movement design of the yarn spindles, the movement trajectory of the yarn spindles is flexibly controlled to realize the preparation of the coupled structure preform. The process is simple, highly operable, improves the practical value of the preform, and has good engineering application prospects. In addition, compared with changing the movement trajectories of most yarns in multiple yarn systems, the conversion design method for adjusting the fiber orientation only needs to selectively change the movement trajectories of some yarns in a single yarn system, significantly reducing the complexity of the process. Description of the Drawings

[0029] Figure 1 It is a simplified schematic diagram of a variable-thickness flat plate for a fan blade;

[0030] Figure 2 It is a schematic diagram of the overall structure of the prefabricated fabric for a fan blade;

[0031] Figure 3 It is an enlarged schematic diagram of the high-thickness fabric area;

[0032] Figure 4 It is an enlarged schematic diagram of the thickness-reduced fabric area;

[0033] Figure 5 It is a schematic diagram of the plane of the first column of warp yarns;

[0034] Figure 6 It is a schematic diagram of the plane of the first column of backing warp yarns;

[0035] Figure 7It is a schematic diagram of the warp plane of the second column;

[0036] Figure 8 It is a schematic diagram of the warp-lining plane of the second column;

[0037] In the figure, 1 is the high-thickness fabric area, 11 is the flat fabric area, 12 is the variable-thickness fabric area, 2 is the thickness-reducing fabric area, 3 is the warp, 4 is the weft, 5 is the warp-lining, 6 is the diagonal yarn, 61 is the +θ-angle diagonal yarn, and 62 is the -θ-angle diagonal yarn. Specific implementation mode

[0038] To further disclose the content, features and effects of the present invention, the following examples are specifically given and described in detail in conjunction with the drawings. In the description of the following embodiments, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing this patent and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to this patent.

[0039] In the description of the following embodiments, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", "connection", "setting" should be understood in a broad sense. For example, it can be fixedly connected and set, or detachably connected and set, or integrally connected and set. For those of ordinary skill in the art, the specific meanings of the above terms in this patent can be understood according to specific situations.

[0040] Embodiment 1: Refer to the appendix Figure 1-8 , according to the topological principle, without considering the size and shape factors of the fan blade, the existing fan blade with a curved and twisted large aspect ratio swept shape structure (not shown) can be flattened into a variable-thickness flat plate (as Figure 1 shown), the thickness of which has the characteristic of continuous and uniform change. Then, a variable-thickness three-dimensional woven preform of the fan blade obtained by profile weaving according to this characteristic requirement (as Figure 2 shown) can be divided into two areas: the high-thickness fabric area 1 and the thickness-reducing fabric area 2, corresponding to the tenon and the blade body of the fan blade respectively; the high-thickness fabric area 1 (as Figure 3 shown) is divided into the flat fabric area 11 and the variable-thickness fabric area 12, and includes the warp 3, the weft 4 and the warp-lining 5; the thickness-reducing fabric area (as Figure 4As shown in the figure, it includes warp yarns 3, weft yarns 4, warp-lining yarns 5 and diagonal yarns 6, where the diagonal yarns 6 further include +θ angle diagonal yarns 61 and -θ angle diagonal yarns 62; the warp yarns 1 and warp-lining yarns 2 are along the length direction of the preform, and are connected to the thickness-reducing fabric area 2 after passing through the thickness-increasing fabric area 12 from the flat fabric area 11. In the thickness-increasing fabric area 12, the fabric thickness is continuously reduced along the length direction of the preform by reducing the number of inner-layer weft yarns 4 and cutting the corresponding warp yarns 3 and warp-lining yarns 5; the remaining warp-lining yarns 5 in the thickness-increasing fabric area 12 continue to be used as warp-lining yarns 5 after entering the thickness-reducing fabric area 2, and the rest are deflected in-plane, thus being converted into the diagonal yarns 6 of the thickness-reducing fabric area 2; the remaining yarns in the high-thickness fabric area 1 and the thickness-reducing fabric area 2 are bundled together by the warp yarns 1 to form a coupled structure preform as a whole.

[0041] Among the remaining warp-lining yarns in the thickness-increasing fabric area 12, those close to the fabric surface and those close to the fabric center continue to be used as warp-lining yarns 5, and some of the inner-layer warp-lining yarns 5 are deflected in-plane and converted into diagonal yarns 6. This is because the movement law of the warp-lining yarns 5 is the simplest, only keeping straight in the fabric length direction, and it is easier to operate on the loom actually by deflecting it in-plane.

[0042] The inner-layer warp-lining yarns 5 in the thickness-reducing fabric area 2 need to be selectively deflected in-plane (the deflection principle is to reasonably control the content, position and angle of the diagonal yarns 6, and it is specifically designed according to the size and mechanical property requirements of the preform). After deflection, there is at least one group of diagonal yarns 6 in the preform thickness direction, and each group is divided into +θ angle diagonal yarns 61 and -θ angle diagonal yarns 62. The inclination angle of the diagonal yarns 6 in the preform length direction is 30° - 60°; when the number of diagonal yarns 6 in the preform is an even number of groups, different groups of diagonal yarns 6 are symmetrically arranged and distributed between the preform layers. This not only ensures the volume content of the main load-bearing fibers in the preform length direction and thus can reduce the loss of tensile properties, but also achieves the purpose of improving the impact resistance.

[0043] The drawings used in this embodiment are only examples and are not drawn according to the condition of equal proportion, and should not be used to limit the actual protection scope required by the present invention. It should be noted that since it is considered that the load-bearing situation in the working state of the blade body and tenon connection area is complex and has become the current key attention area, only this part is selected for flattening treatment to obtain a flat prefabricated fabric, which is convenient for subsequent specific description of the fabric thickness change and the process of introducing diagonal yarns.

[0044] A variable-thickness coupling structure preform for a fan blade with adjustable fiber orientation, the fabric width is 200 mm, the warp yarn 3 is a single ply of carbon fiber T800-6k, and the weft yarn 4, the warp backing yarn 5, and the bias yarn 6 are all two-ply of carbon fiber T800-6k. The warp backing yarn 5 (represented by 0), the +θ angle bias yarn 61 (represented by +θ), and the -θ angle bias yarn 62 (represented by -θ). This preform is continuously woven from the high-thickness fabric area 1 to the reduced-thickness fabric area 2 along the length direction of the preform. For the reduced-thickness fabric area 2 containing the bias yarn 6, the yarn arrangement in the thickness direction is designed as [0 / +45 / -45 / 0] 2S , the subscript 2 represents the order of arrangement, and S represents the up-and-down symmetric arrangement. The arrangement density of the warp yarn and the warp backing yarn is both 4 per cm, and the arrangement density of the weft yarn is 4 per cm.

[0045] Example 2: Refer to the appendix Figure 2-8 , taking the following preform process parameters as an example, ① The number of warp yarn columns N = fabric width × fabric density = 200 / 10 × 4 = 80 columns. The number of warp yarn layers in the high-thickness fabric area is 16 layers, and the number of warp yarn layers in the reduced-thickness fabric area is 8 layers; ② The number of bias yarn columns M = the number of warp backing yarn columns O = the number of warp yarn columns N - 1 = 79 columns. The number of warp backing yarn layers in the high-thickness fabric area is 16 layers, and the number of warp backing yarn layers and bias yarn layers in the reduced-thickness fabric area are both 4 layers; ③ The inclination angle θ of the bias yarn = tan -1 (weft yarn density / warp yarn density) = tan -1 (4 / 4) = 45°.

[0046] The preparation method of this preform specifically includes the following steps:

[0047] (1) Arrangement of main yarns: The warp yarn 3 and the warp backing yarn 5 are initially arranged in the high-thickness fabric area 1. The warp yarn is arranged in 16 layers and 80 columns, and the warp backing yarn is arranged in 16 layers and 79 columns; during the thickening process from the high-thickness fabric area 1 to the reduced-thickness fabric area 2, the warp yarn 3 and the warp backing yarn 5 are rearranged in the thickening fabric area 12. The warp yarn 3 is arranged from 16 layers and 80 columns to 8 layers and 80 columns, and the warp backing yarn 5 is arranged from 16 layers and 79 columns to 8 layers and 79 columns; in the thickening fabric area 12, the fabric thickness is continuously reduced along the length direction of the preform by reducing the number of inner-layer weft yarn 4 layers and cutting the corresponding warp yarn 3 and warp backing yarn 5. After the thickening is completed, a part of the remaining warp backing yarn 5 in the thickening fabric area 12 continues to be used as the warp backing yarn 5 after entering the reduced-thickness fabric area 2, and the rest are deflected in the plane, thus being converted into the bias yarn 6 of the reduced-thickness fabric area 2; the warp yarn 3, the warp backing yarn 5, and the bias yarn 6 are rearranged in the reduced-thickness fabric area 2. The warp yarn 3 is arranged in 8 layers and 80 columns, the warp backing yarn 5 is arranged in 4 layers and 79 columns, and the bias yarn 6 is arranged in 4 layers and 79 columns; the edge yarns of the bias yarn 6 are respectively arranged initially in the reduced-thickness fabric area 2.

[0048] For simplicity of illustration, the warp arrangement in the high-thickness fabric area 1 is 16 layers by 14 columns, and the backing warp arrangement is 16 layers by 13 columns; the warp arrangement in the thickness-reducing fabric area 2 is 8 layers by 14 columns, the backing warp arrangement is 4 layers by 13 columns, the diagonal yarn arrangement is 4 layers by 13 columns, and the +θ-angle diagonal yarn and -θ-angle diagonal yarn arrangements are both 2 layers by 13 columns. Specifically, the spindles of the warp yarn 3 are arranged on the guide bars of the warp yarn 3, and the spindles in both the high-thickness fabric area 1 and the thickness-reducing fabric area 2 are arranged in a regular quadrilateral pattern; the geometric size and mesoscopic parameters of the preform of the variable-thickness coupling structure for the fan blade need to be set according to the project requirements. The number of rows and columns of the main yarn can be specifically designed according to the external dimensions and weaving parameters of the prefabricated fabric for the fan blade.

[0049] The initial arrangement of the edge yarns of the diagonal yarn 6 in the thickness-reducing fabric area 2; there is a guide yarn side bar for the diagonal yarn 6 at each of the left and right edges of the thickness-reducing fabric area 2. One +θ-angle diagonal yarn 61 is arranged on the spindle of the left-edge yarn in the thickness-reducing fabric area 2; one -θ-angle diagonal yarn 62 is arranged on the spindle of the right-edge yarn in the thickness-reducing fabric area.

[0050] (2) Warp shedding motion: Complete the column-wise misalignment of the equipment warps according to the motion law of the warps in the plain-layer coupled angle-interlock structure, driving the warp yarn 3 to form a warp shed. Specifically, the shedding motion of the warp yarn 3 includes the shedding motion in the high-thickness fabric area 1 and the thickness-reducing fabric area 2, and the motion direction of the warp yarn 3 in both areas is parallel to the direction of the backing warp 5 in the variable-thickness three-dimensional woven preform for the fan blade; in addition, the backing warp spindles in the plain fabric area 11 remain stationary during the weaving process.

[0051] (3) Diagonal yarn motion: During the weaving process in the high-thickness fabric area, this step can be skipped and the remaining steps can be carried out; during the weaving process in the thickness-reducing fabric area, this step needs to be completed before the remaining steps can be carried out. Therefore, the diagonal yarn 6 only moves in the thickness-reducing fabric area 2. Specifically, adjacent diagonal yarn spindles form a group, and there are 2 groups in the thickness-reducing fabric area 2; the +θ-angle diagonal yarn spindles move one yarn pitch to the right, the -θ-angle diagonal yarn spindles move one yarn pitch to the left, the side yarn spindles of the +θ-angle diagonal yarn 61 move to the layer of the adjacent -θ-angle diagonal yarn spindles, and the side yarn spindles of the -θ-angle diagonal yarn 62 move to the layer of the adjacent +θ-angle diagonal yarn spindles.

[0052] The introduction of the diagonal yarn 6 is achieved by alternately adding a side yarn spindle on both sides of the partial warp yarn 5 yarn layer corresponding to the thickening fabric area 22, and finally deflecting and converting the partial warp yarn 5 after the thickness change of the high-thickness fabric area 1 into the diagonal yarn 6. The number of positions of the diagonal yarn spindle (i.e., the original warp yarn spindle) moving along the row direction can be adjusted according to the design, and the number of positions of the +θ diagonal yarn spindle moving along the row direction is the same as that of the -θ diagonal yarn spindle moving along the row direction. The number of positions of the side yarn spindle of the diagonal yarn 6 moving along the column direction is determined by the number of spacer layers between the same group of +θ diagonal yarn layers and +θ diagonal yarn layers, and can be adjusted according to the design.

[0053] (4) Weft insertion: In the formed warp opening, the weft yarn 5 is sequentially inserted into each warp opening by the weft yarn device.

[0054] (5) Pressing the weft yarn: The yarn pressing device is inserted between the columns of the warp yarn 3, translated towards the cloth fell, and the weft yarn 5 is beaten into the cloth fell, and then the yarn pressing device is withdrawn.

[0055] (6) Repeat the steps (2)-(5) until the target length of the fabric is reached, stop the fabric weaving, cut off the yarn from the cloth fell, and finally obtain a variable-thickness coupled structure preform with adjustable fiber orientation. The arrangement of the diagonal yarns 6 in the preform is [0 / +45 / -45 / 0], [0 / -45 / +45 / 0], and they are arranged in an upper and lower anti-symmetric manner. The target length of the fabric is set according to the user's requirements.

[0056] It should be noted that in the above weaving process, the specific operation process of reducing the number of inner layer yarns and converting different yarn systems in this embodiment is as follows:

[0057] As Figure 5 shown in FIG. -8, are four schematic cross-sectional views of the variable-thickness coupled structure preform for a fan blade in this embodiment sequentially cut along the direction perpendicular to the weft yarn. Among them, the weft yarn 5 extends in the direction perpendicular to the paper surface. Figure 5 、 7 are respectively the schematic cross-sectional views of the adjacent first column of warp yarns a1 and the second column of warp yarns a2. Figure 6 、 8 are respectively the schematic cross-sectional views of the adjacent first column of warp yarns b1 and the second column of warp yarns b2. The first column of warp yarns a1 includes 16 layers of warp yarns a11 - a116, and the second column of warp yarns a2 includes 16 layers of warp yarns a21 - a216; the first column of warp yarns b1 includes 16 layers of warp yarns b11 - b116, and the second column of warp yarns b2 includes 16 layers of warp yarns b21 - b216.

[0058] When weaving to the 4th weft, the flat fabric area 21 ends, and the thickening fabric area 22 begins, while retaining the middle layer weft yarns and gradually reducing 1 layer of weft yarns towards the upper and lower surfaces respectively. The thickening fabric area 22 contains 5 columns of weft yarns. The 5th column has 2 fewer internal weft rows compared to the 6th column, the 6th column has 2 fewer internal weft rows compared to the 7th column, the 7th column has 2 fewer internal weft rows compared to the 8th column, and the 8th column has 2 fewer internal weft rows compared to the 9th column.

[0059] As Figure 5 , shown in Figure 6, the specific yarn reduction process of the first column of warp yarns a1 and the first column of backing warp yarns b1 is as follows:

[0060] At the 5th weft, the 8th and 10th layer weft yarns are subtracted. The warp yarn a17 and the backing warp yarn b17 are both cut at the yarn reduction point c1 at the 5th weft, and the warp yarn a110 and the backing warp yarn b110 are both cut at the yarn reduction point c2 at the 4th weft. Subsequently, the remaining warp yarns and backing warp yarns on both sides move towards the middle by one yarn pitch;

[0061] At the 6th weft, the 7th and 11th layer weft yarns are subtracted. The warp yarn a16 and the backing warp yarn b16 are both cut at the yarn reduction point c3 at the 5th weft, and the warp yarn a111 and the backing warp yarn b111 are both cut at the yarn reduction point c4 at the 6th weft. Subsequently, the remaining warp yarns and backing warp yarns on both sides move towards the middle by one yarn pitch;

[0062] At the 7th weft, the 6th and 12th layer weft yarns are subtracted. The warp yarn a15 and the backing warp yarn b15 are both cut at the yarn reduction point c5 at the 7th weft, and the warp yarn a112 and the backing warp yarn b112 are both cut at the yarn reduction point c6 at the 6th weft. Subsequently, the remaining warp yarns and backing warp yarns on both sides move towards the middle by one yarn pitch;

[0063] At the 8th weft, the 5th and 13th layer weft yarns are subtracted. The warp yarn a14 and the backing warp yarn b14 are both cut at the yarn reduction point c7 at the 7th weft, and the warp yarn a113 and the backing warp yarn b113 are both cut at the yarn reduction point c8 at the 8th weft. Subsequently, the remaining warp yarns and backing warp yarns on both sides move towards the middle by one yarn pitch;

[0064] As Figure 7 , shown in Figure 8, the specific yarn reduction process of the second column of warp yarns a2 and the second column of backing warp yarns b2 is as follows:

[0065] At the 5th weft, the 8th and 10th layer weft yarns are subtracted. The warp yarn a28 and the backing warp yarn b28 are both cut at the yarn reduction point c9 at the 4th weft, and the warp yarn a211 and the backing warp yarn b211 are both cut at the yarn reduction point c10 at the 5th weft. Subsequently, the remaining warp yarns and backing warp yarns on both sides move towards the middle by one yarn pitch;

[0066] At the 6th weft, the 7th and 11th layer weft yarns are subtracted. The warp yarn a27 and the warp-lining yarn b27 are both cut at the yarn subtraction point c11 at the 6th weft, and the warp yarn a212 and the warp-lining yarn b212 are both cut at the yarn subtraction point c12 at the 5th weft. Subsequently, the remaining warp yarns and warp-lining yarns on both sides move one yarn pitch towards the middle;

[0067] At the 7th weft, the 6th and 12th layer weft yarns are subtracted. The warp yarn a26 and the warp-lining yarn b26 are both cut at the yarn subtraction point c13 at the 6th weft, and the warp yarn a213 and the warp-lining yarn b213 are both cut at the yarn subtraction point c14 at the 7th weft. Subsequently, the remaining warp yarns and warp-lining yarns on both sides move one yarn pitch towards the middle;

[0068] At the 8th weft, the 5th and 13th layer weft yarns are subtracted. The warp yarn a25 and the warp-lining yarn b25 are both cut at the yarn subtraction point c15 at the 8th weft, and the warp yarn a214 and the warp-lining yarn b214 are both cut at the yarn subtraction point c16 at the 7th weft. Subsequently, the remaining warp yarns and warp-lining yarns on both sides move one yarn pitch towards the middle;

[0069] In addition, since the 9th layer weft yarn is the middle layer weft yarn and is retained, the warp yarns a18, a19, a28, a29 that are interwoven with this layer of weft yarn and the warp-lining yarns b18, b19, b28, b29 paired with the corresponding warp yarns are also retained, and the retained warp yarns and warp-lining yarns do not need to shift yarns.

[0070] When weaving between the 8th and 9th wefts, after the preform thickness transition is completed, some of the warp-lining yarns in the high-thickness fabric area are selectively deflected in-plane to become the diagonal yarns in the thickness-reducing fabric area. The two pairs of warp-lining yarns (b11, b116 and b21, b216) close to the fabric surface and the two pairs of warp-lining yarns (b18, b19 and b28, b29) close to the fabric center do not deflect and remain straight, while the remaining warp-lining yarns deflect in-plane.

[0071] As Figure 6 , shown in Figure 8, the specific operation process of the conversion of different yarn systems is as follows:

[0072] In the first column of the warp-lining yarn plane, adjacent warp-lining yarns b12 and b13 deflect to form a set of diagonal yarns. The warp-lining yarn b12 becomes a diagonal yarn at an angle of +θ, and the warp-lining yarn b13 becomes a diagonal yarn at an angle of -θ. The spindle of the +θ diagonal yarn moves one yarn pitch to the right along the row, the spindle of the -θ diagonal yarn moves one yarn pitch to the left along the row, the side-yarn spindle of the +θ diagonal yarn moves two yarn pitches downward along the column, and the side-yarn spindle of the -θ diagonal yarn moves two yarn pitches upward along the column; adjacent warp-lining yarns b114 and b115 deflect to form another set of diagonal yarns. The warp-lining yarn b114 becomes a diagonal yarn at an angle of -θ, and the warp-lining yarn b115 becomes a diagonal yarn at an angle of +θ. The spindle of the +θ diagonal yarn moves one yarn pitch to the right along the row, the spindle of the -θ diagonal yarn moves one yarn pitch to the left along the row, the side-yarn spindle of the +θ diagonal yarn moves two yarn pitches upward along the column, and the side-yarn spindle of the -θ diagonal yarn moves two yarn pitches downward along the column;

[0073] In the second column of the warp-lining yarn plane, adjacent warp-lining yarns b22 and b23 deflect to form a set of diagonal yarns. The warp-lining yarn b22 becomes a diagonal yarn at an angle of +θ, and the warp-lining yarn b23 becomes a diagonal yarn at an angle of -θ. The spindle of the +θ diagonal yarn moves one yarn pitch to the right along the row, the spindle of the -θ diagonal yarn moves one yarn pitch to the left along the row, the side-yarn spindle of the +θ diagonal yarn moves two yarn pitches downward along the column, and the side-yarn spindle of the -θ diagonal yarn moves two yarn pitches upward along the column; adjacent warp-lining yarns b214 and b215 deflect to form another set of diagonal yarns. The warp-lining yarn b214 becomes a diagonal yarn at an angle of -θ, and the warp-lining yarn b215 becomes a diagonal yarn at an angle of +θ. The spindle of the +θ diagonal yarn moves one yarn pitch to the right along the row, the spindle of the -θ diagonal yarn moves one yarn pitch to the left along the row, the side-yarn spindle of the +θ diagonal yarn moves two yarn pitches upward along the column, and the side-yarn spindle of the -θ diagonal yarn moves two yarn pitches downward along the column.

[0074] As a supplement to the above, the smallest tissue repeat unit composed of the first-column warp yarns, the second-column warp yarns, the first-column warp-lining yarns, and the second-column warp-lining yarns can be continuously extended in the width of the preform.

[0075] As a supplement to the above, the method of changing the angle θ of the diagonal yarn 6 is to change the arrangement density of the warp yarn 3, the warp-lining yarn 5, and the weft yarn 4, or to change the coordination between the step motion of the diagonal yarn 6 and the introduction of the weft yarn 4, or to use a combination of the above two methods; the coordination between the step motion of the diagonal yarn 6 and the introduction of the weft yarn 4 refers to increasing the number of motion steps of the diagonal yarn 6 to increase the angle θ of the diagonal yarn 6, or decreasing the number of times of introducing the weft yarn 4 to increase the angle θ of the diagonal yarn 6.

[0076] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit of the present invention and the scope protected by the claims. All of these fall within the protection scope of the present invention.

Claims

1. A preform of a variable-thickness coupling structure with adjustable fiber orientation, comprising two parts: a high-thickness fabric area and a thickness-reduced fabric area, corresponding to the tenon part and the blade body part of the fan blade respectively, characterized in that: The high-thickness fabric area is divided into a flat fabric area and a variable-thickness fabric area; both the high-thickness fabric area and the thickness-reducing fabric area include warp yarns, weft yarns and lining warp yarns; and the thickness-reducing fabric area further includes diagonal yarns; the warp yarns and the lining warp yarns are along the length direction of the preform, and are connected to the thickness-reducing fabric area after passing through the variable-thickness fabric area from the flat fabric area; in the variable-thickness fabric area, the fabric thickness is continuously reduced along the length direction of the preform by reducing the number of inner-layer weft yarn layers and cutting the corresponding warp yarns and lining warp yarns; the remaining lining warp yarns in the variable-thickness fabric area continue to be used as lining warp yarns after entering the thickness-reducing fabric area, and the rest are deflected in-plane, so as to be converted into the diagonal yarns of the thickness-reducing fabric area; The remaining yarns in the high-thickness fabric area and the thickness-reducing fabric area are bundled together by the warp yarns, so as to integrally weave a coupling structure preform; the lining warp yarns close to the fabric surface and close to the fabric center in the remaining lining warp yarns in the thickness-reducing fabric area continue to be used as lining warp yarns, and part of the inner-layer lining warp yarns are deflected in-plane and converted into diagonal yarns.

2. The preform of the variable-thickness coupling structure with adjustable fiber orientation according to claim 1, characterized in that: The lining warp yarns in the inner layer of the thickness-reducing fabric area need to be selectively deflected in-plane. After deflection, there is at least one group of diagonal yarns in the thickness direction of the preform. Each group is divided into +θ-angle diagonal yarns and -θ-angle diagonal yarns, and the inclination angle of the diagonal yarns in the length direction of the preform is 30°-60°; when the number of diagonal yarn groups in the preform is an even number, different groups of diagonal yarns are symmetrically arranged and distributed between the preform layers.

3. The preform of the variable-thickness coupling structure with adjustable fiber orientation according to claim 2, wherein: When there are two groups of diagonal yarns in the thickness direction of the preform, the two groups of diagonal yarns are symmetrically distributed in the position between the preform layers; when the inclination angle of the diagonal yarns is 45°, the impact resistance of the preform is the best.

4. The preform of the variable-thickness coupling structure with adjustable fiber orientation according to claim 1, characterized in that: Both the high-thickness fabric area and the thickness-reducing fabric area adopt a plain weave interlayer angle interlock structure as the basic tissue structure, and the warp yarns bundle the remaining yarns together according to the movement law of the plain weave in the fabric layers.

5. A preparation method of a variable-thickness coupled structure preform with adjustable fiber orientation, for preparing the preform according to any one of claims 1-4, characterized in that Including the following steps: (1) Arrangement of main yarns: The warp yarns and the lining warp yarns are initially arranged in the high-thickness fabric area; During the thickening process from the high-thickness fabric area to the thickness-reducing fabric area, the warp yarns and the lining warp yarns are rearranged in the variable-thickness fabric area; In the variable-thickness fabric area, the fabric thickness is continuously reduced along the length direction of the preform by reducing the number of inner-layer weft yarn layers and cutting the corresponding warp yarns and lining warp yarns. After the thickening is completed, the remaining lining warp yarns in the variable-thickness fabric area continue to be used as lining warp yarns after entering the thickness-reducing fabric area, and the rest are deflected in-plane, so as to be converted into the diagonal yarns of the thickness-reducing fabric area; finally, the warp yarns, the lining warp yarns and the diagonal yarns are rearranged in the thickness-reducing fabric area, and the edge yarns of the diagonal yarns are initially arranged in the thickness-reducing fabric area; (2) Warp yarn shedding motion: According to the movement law of the warp yarns of the plain weave interlayer angle interlock structure, the columnar misalignment of the warp yarns of the equipment is completed, and the warp yarns are driven to form a warp yarn shed; (3) Introduction of diagonal yarns: During the weaving process in the high-thickness fabric area, this step is skipped and the remaining steps are carried out; during the weaving process in the thickness-reducing fabric area, this step needs to be completed before the remaining steps are carried out, so the diagonal yarns only move in the thickness-reducing fabric area; (4) Introduction of weft yarns: In the formed warp yarn shed, the weft yarns are sequentially introduced into each warp yarn shed by the weft yarn device; (5) Pressing the weft yarns: The yarn pressing device is inserted into the columns of the warp yarns, translated towards the cloth fell, beats the weft yarns into the cloth fell, and withdraws the yarn pressing device; (6) Repeat the steps (2)-(5) until the target length of the fabric is reached, stop the fabric weaving, cut off the yarn from the fell of the loom, and finally obtain a preform of a variable-thickness coupling structure with adjustable fiber orientation.

6. The preparation method of the variable-thickness coupling structure preform with adjustable fiber orientation according to claim 5, characterized in that: In the step (1), the yarn bobbins of the warp yarns are arranged on the warp guides, and the yarn bobbins in both the high-thickness fabric area and the thickness-reducing fabric area are arranged in a regular quadrilateral pattern; the edge yarns of the diagonal yarns are initially arranged in the thickness-reducing fabric area, and there is a yarn guiding edge strip for the diagonal yarns on each of the left and right edges of the thickness-reducing fabric area. One +θ-angle diagonal yarn is arranged on the yarn bobbins of the edge yarns on the left edge of the thickness-reducing fabric area; one -θ-angle diagonal yarn is arranged on the yarn bobbins of the edge yarns on the right edge of the thickness-reducing fabric area.

7. The preparation method of the variable-thickness coupling structure preform with adjustable fiber orientation according to claim 5, characterized in that: In the step (2), the shedding motion of the warp yarns includes the shedding motion in both the high-thickness fabric area and the thickness-reducing fabric area, and the motion directions of the warp yarns in both areas are parallel to the direction of the warp yarns in the preform; in addition, the warp yarn bobbins in the flat fabric area remain stationary during the weaving process.

8. The preparation method of the variable-thickness coupling structure preform with adjustable fiber orientation according to claim 5, characterized in that: In the step (3), adjacent diagonal yarn bobbins are grouped, and there are 2 groups in total in the thickness-reducing fabric area; the +θ-angle diagonal yarn bobbins move one step to the right, the -θ-angle diagonal yarn bobbins move one step to the left, the edge yarn bobbins of the +θ-angle diagonal yarn move to the layer of the adjacent -θ-angle diagonal yarn bobbins, and the edge yarn bobbins of the -θ-angle diagonal yarn move to the layer of the adjacent +θ-angle diagonal yarn bobbins.

9. The preparation method of the variable-thickness coupled structure preform with adjustable fiber orientation according to claim 5, characterized in that: The method for changing the angle θ of the diagonal yarn is to change the arrangement density of the warp yarns, the warp yarns in the lining, and the weft yarns, or to change the coordination of the stepping motion of the diagonal yarn and the introduction of the weft yarn, or to use a combination of the above two methods; the change in the coordination of the stepping motion of the diagonal yarn and the introduction of the weft yarn means increasing the angle θ of the diagonal yarn by increasing the number of motion steps of the diagonal yarn, or increasing the angle θ of the diagonal yarn by reducing the number of times the weft yarn is introduced.

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