Preparation method of three-dimensional woven wing leading edge prefabricated body based on parametric modeling, wing leading edge three-dimensional woven composite material and preparation method of wing leading edge three-dimensional woven composite material

Abstract

The invention discloses a preparation method of a three-dimensional woven wing leading edge prefabricated body based on parametric modeling, a wing leading edge three-dimensional woven composite material and a preparation method thereof, and relates to the field of aircraft structure design. Based on wing design parameters, a parametric geometric model of the outer surface of a wing is constructed; based on the unit normal vector of the parameterized geometric model, the parameterized geometric model is biased in the normal direction, and an initial wing leading edge core model geometric model is obtained; the wing leading edge area of the initial wing leading edge core model geometric model is symmetrical along a symmetry plane, smooth transition is carried out, and a closed wing leading edge core model geometric model is formed; manufacturing a closed mandrel according to the closed wing leading edge mandrel geometric model; and performing three-dimensional weaving around the closed core mold, and then performing demolding and cutting in sequence to obtain the three-dimensional woven wing leading edge preform. The method is suitable for the wing leading edge with the variable cross-section characteristic, errors generated by relying on manual drawing and empirical modeling can be avoided, and the forming precision of the wing leading edge skin is improved.

Description

Technical Field

[0001] This application relates to the field of aircraft structural design, and in particular to a method for preparing a three-dimensional braided wing leading edge preform based on parametric modeling, a three-dimensional braided wing leading edge composite material and its preparation method. Background Technology

[0002] Driven by the demand for lightweight aerospace structures, aircraft structural design is gradually transitioning from traditional metallic materials to composite materials. However, common laminated composite materials are prone to interlaminar separation and interface failure under complex loads, making it difficult to guarantee structural safety. In contrast, three-dimensional composite materials feature continuously interwoven fiber bundles in space, forming a more integrated three-dimensional spatial network that achieves both lightweighting and higher integrity and stability. Typical three-dimensional composite materials include three-dimensional woven composites and three-dimensional braided composites. Three-dimensional woven composites typically rely on the interweaving of warp and weft yarns and Z-axis yarns in the thickness direction, and are commonly used in plate and shell structures. Three-dimensional braided composites, on the other hand, use a circular braiding machine to continuously interweave fiber bundles under certain tension in three dimensions, allowing for direct integral weaving on complex curved surfaces or mandrels with significant curvature variations, making them more suitable for manufacturing complex shapes.

[0003] The leading edge of an aircraft wing has a complex curved surface shape, and the airfoil may vary at different sites. Traditional mold design methods that rely on experience often fail to guarantee structural accuracy and consistency. Summary of the Invention

[0004] The purpose of this application is to provide a method for preparing a three-dimensional braided wing leading edge preform based on parametric modeling, a three-dimensional braided wing leading edge composite material and its preparation method, so as to improve the forming accuracy of the wing leading edge skin.

[0005] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a method for fabricating a three-dimensional woven wing leading edge preform based on parametric modeling, including: Based on the wing design parameters, a parametric geometric model of the wing's outer surface is constructed using the CST parametric method; Based on the unit normal vector of the parametric geometric model, the parametric geometric model is offset along the normal of the aerodynamic shape surface to obtain the initial wing leading edge core model geometric model. The wing leading edge region of the initial wing leading edge mandrel geometric model is symmetrical along the plane of symmetry and smoothly transitioned to form a closed wing leading edge mandrel geometric model; the plane of symmetry is the plane perpendicular to the airfoil chord line where the wing leading edge plus the cutting and trimming allowance is located; Manufacture a closed core mold based on the geometric model of the leading edge core mold of the closed wing; The closed mandrel is woven in three dimensions, and then demolded and cut in sequence to obtain a three-dimensional woven wing leading edge preform. The three-dimensional weaving process parameters are obtained by solving the yarn path length factor based on the cross-sectional geometric parameters of the closed mandrel along the spanwise direction. The cutting is carried out on the surface of the closed mandrel according to a preset space curve.

[0006] In one embodiment, the wing design parameters include wing span, wing leading edge sweep angle, wing dihedral angle, wing reference axis, wing chord length at any spanwise position, and wing local twist angle at any spanwise position.

[0007] In one embodiment, a parametric geometric model of the wing's outer surface is constructed based on wing design parameters, specifically including: Based on the stated wing span, the normalized spanwise coordinates on the wing are determined as follows: The airfoil section in the global coordinate system coordinate; Based on the normalized spanwise coordinates of the wing The airfoil section in the global coordinate system Using the coordinates and the sweep angle of the wing leading edge, determine the airfoil leading edge point in the global coordinate system. coordinate; Based on the normalized spanwise coordinates of the wing The airfoil section chord length and the airfoil leading edge point in the global coordinate system Coordinates, determining the reference axis in the global coordinate system coordinate; Based on the normalized spanwise coordinates of the wing The airfoil section in the global coordinate system Using coordinates and the dihedral angle of the wing, determine the reference axis in the global coordinate system. coordinate; Using the shape function transformation method, the normalized spanwise coordinates of the wing in the local coordinate system are determined as follows: The upper and lower surface curves of the airfoil at the cross-section; Based on the normalized spanwise coordinates of the wing The wing chord length is used to determine the X-coordinate of the normalized chord coordinate u on the wing in the local coordinate system; Based on the normalized spanwise coordinates of the wing in the local coordinate system: The upper and lower surface curves of the airfoil at the cross-section, as well as the normalized spanwise coordinates of the wing, are as follows: The wing chord length determines the altitude coordinates of the airfoil surface in the local coordinate system; the altitude coordinates of the airfoil surface in the local coordinate system include the altitude coordinates of the upper surface of the airfoil and the altitude coordinates of the lower surface of the airfoil in the local coordinate system. The normalized spanwise coordinates on the wing in the local coordinate system are: The point with normalized chord coordinate u is rotated about the reference axis by the local twist angle of the wing. The normalized spanwise coordinate of the wing in the local coordinate system is then determined. The normalized chord coordinates, height coordinates, and span coordinates of a point with chord coordinate u in the global coordinate system; Based on the normalized spanwise coordinates of the wing in the local coordinate system: The normalized chord coordinates, altitude coordinates, and span coordinates of a point with chord coordinate u in the global coordinate system are used to determine the parametric geometric model of the outer surface of the wing.

[0008] In one embodiment, the parametric geometric model of the wing's outer surface is: ; in, To normalize the spanwise coordinates of the wing in the local coordinate system as follows: The normalized chord coordinates of a point with chord coordinate u in the global coordinate system; To normalize the spanwise coordinates of the wing in the local coordinate system as follows: The span coordinates of a point with normalized chord coordinate u in the global coordinate system; To normalize the spanwise coordinates of the wing in the local coordinate system as follows: The height coordinates of a point with normalized chordal coordinate u in the global coordinate system.

[0009] In one embodiment, based on the unit normal vector of the parametric geometric model, the parametric geometric model is offset along the normal direction to obtain an initial wing leading edge core model geometric model, specifically including: Based on the parametric geometric model, the rate of change of coordinates in the chord direction and the rate of change of coordinates in the spanwise direction are calculated for any point on the wing; The outward normal direction vector is determined based on the rate of change of the coordinates in the chord direction and the rate of change of the coordinates in the span direction; Determine the unit normal vector of the parametric geometric model based on the outward normal direction vector; The normal offset is determined based on the thickness of the three-dimensional woven preform and the assembly trimming allowance. Based on the unit normal vector, the parameterized geometric model is offset by a normal offset along the normal direction into the wing interior to obtain the initial wing leading edge core geometric model.

[0010] In one embodiment, the initial wing leading edge mandrel geometry is as follows: ; in, A parametric geometric model of the wing's outer surface; This refers to the normal offset of the parametric geometric model; This is the unit normal vector of the parametric geometric model.

[0011] In one embodiment, the leading edge region of the wing is ;in, , ,and .

[0012] Secondly, this application provides a three-dimensional braided composite material for the leading edge of a wing, comprising a resin matrix and a reinforcing material, wherein the reinforcing material comprises the three-dimensional braided wing leading edge preform described in the above technical solution.

[0013] In one embodiment, the reinforcing material further includes an energy-absorbing layer and an energy-absorbing layer capping layer, wherein the three-dimensional woven wing leading edge preform, the energy-absorbing layer, and the energy-absorbing layer capping layer are stacked sequentially.

[0014] Thirdly, this application provides a method for preparing the three-dimensional braided composite material for the leading edge of the wing as described in the above technical solution, wherein the reinforcing material is placed in a curing mold and resin transfer molding is performed to obtain the three-dimensional braided composite material for the leading edge of the wing.

[0015] According to the specific embodiments provided in this application, this application has the following technical effects: This application provides a method for preparing a three-dimensional woven wing leading edge preform based on parametric modeling, a three-dimensional woven wing leading edge composite material, and the same method. Based on wing design parameters, a parametric geometric model of the wing's outer surface is constructed. Based on the unit normal vector of the parametric geometric model, the model is offset along the normal direction to obtain an initial wing leading edge core mold geometric model. The wing leading edge region of the initial wing leading edge core mold geometric model is symmetrically symmetrical along a plane of symmetry and smoothly transitioned to form a closed wing leading edge core mold geometric model. A closed core mold is manufactured based on the closed wing leading edge core mold geometric model. Three-dimensional weaving is performed around the closed core mold, followed by demolding and cutting to obtain the three-dimensional woven wing leading edge preform. Through parametric modeling, the core mold is generated by parametric formulas based on the wing geometry. By symmetrically closing the semi-open wing leading edge geometry, a completely closed core mold structure is formed. This application is applicable to wing leading edges with variable cross-section characteristics, avoids errors caused by relying on manual drawing and experience-based modeling, and improves the forming accuracy of the wing leading edge skin. Attached Figure Description

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

[0017] Figure 1 A schematic flowchart illustrating a method for fabricating a three-dimensional braided wing leading edge preform based on parametric modeling, provided in an embodiment of this application; Figure 2 This is a schematic diagram of the global coordinate system of the wing provided in this application; Figure 3 This is a schematic diagram of the dihedral angle of the wing provided in this application; Figure 4 A schematic diagram of the partial twist angle of the wing provided in this application; Figure 5 This is a schematic diagram of the symmetrical and smooth connection of the core mold provided in this application; Figure 6 A schematic diagram of three-dimensional weaving on a closed mandrel provided in this application; Figure 7 A schematic diagram of the RTM curing of the leading edge of the three-dimensional braided composite wing provided in this application.

[0018] In the figure: 1-Closed core mold, 2-Three-dimensional braided wing leading edge preform, 3-Detailed schematic diagram of the three-dimensional braided preform, 4-Energy-absorbing layer, 5-Energy-absorbing layer sealing layer, 6-Cure outer mold, 7-Cure inner mold. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] This application proposes a method for preparing a three-dimensional braided wing leading edge preform based on parametric modeling, a three-dimensional braided composite material for the wing leading edge and its preparation method, and combines a three-dimensional braided composite material forming process to achieve high-precision manufacturing of the composite wing leading edge while meeting the requirements of lightweighting.

[0022] In one exemplary embodiment, such as Figure 1 As shown, a method for fabricating a three-dimensional braided wing leading edge preform based on parametric modeling is provided, including the following steps: S1: Based on the wing design parameters, a parametric geometric model of the wing's outer surface is constructed using the CST parametric method. The wing design parameters include wing span, wing leading edge sweep angle, wing dihedral angle, wing reference axis, wing chord length at any spanwise position, and wing local twist angle at any spanwise position.

[0023] In this embodiment, a unified parametric geometric model construction method, namely S1, which couples the CST parametric method with structural geometric parameters, is provided, specifically including: S11: Based on the wing span, determine the normalized spanwise coordinates on the wing as follows: The airfoil section in the global coordinate system coordinate.

[0024] Global coordinate system :like Figure 2 As shown, the origin is located at the leading edge of the wing root chord; The axis runs along the aircraft fuselage and points towards the tail of the aircraft; The axis runs along the wingspan and points towards the wingtip; Axis perpendicular to shaft and The axis points upwards from the aircraft.

[0025] Normalized spanwise coordinates on the wing are The airfoil section in the global coordinate system The coordinates are: .

[0026] in, Wing span, wingtip to wingtip length; It is a dimensionless spanning coordinate (normalized spanning coordinate). Indicates wing root, Indicates wingtip.

[0027] S12: Based on the normalized spanwise coordinates of the wing The airfoil section in the global coordinate system Using the coordinates and the sweep angle of the wing leading edge, determine the airfoil leading edge point in the global coordinate system. coordinate.

[0028] The leading edge point of the airfoil in the global coordinate system The coordinates are: .

[0029] in, This refers to the sweep angle of the wing's leading edge.

[0030] S13: Based on the normalized spanwise coordinates of the wing... The airfoil section chord length and the airfoil leading edge point in the global coordinate system Coordinates, determining the reference axis in the global coordinate system coordinate.

[0031] The spanwise reference axis is the dimensionless distance from the leading edge along the chord direction in the airfoil section. The line connecting the points, with the reference axis in the global coordinate system. The coordinates are: .

[0032] in, The normalized spanwise coordinates are The wing chord length (in this embodiment, the airfoil section chord length).

[0033] S14: Based on the normalized spanwise coordinates of the wing... The airfoil section in the global coordinate system Using coordinates and the dihedral angle of the wing, determine the reference axis in the global coordinate system. coordinate.

[0034] Reference axis in the global coordinate system The coordinates are: .

[0035] in, The dihedral angle is defined as the angle extending upwards from the wing root. A schematic diagram of the dihedral angle is shown below. Figure 3 As shown.

[0036] S15: Using the shape-function transformation method, the normalized spanwise coordinates on the wing in the local coordinate system are determined as follows: The upper and lower surface curves of the airfoil at the cross-section.

[0037] Parametric modeling of the upper and lower surface curves of the airfoil employs the Class-Shape Transformation (CST) method, with normalized spanwise coordinates as follows: The curves of the upper and lower surfaces of the airfoil at the cross section are defined as follows: .

[0038] .

[0039] in, It is a normalized chord coordinate (a dimensionless chord coordinate). Indicates the preceding edge, This indicates the trailing edge; the trailing edge of an airfoil does not necessarily pass through the point (1, 0), therefore it is necessary to add a reference to the trailing edge. Make corrections to satisfy the trailing edge boundary conditions; and Normalized span coordinates CST parameter vectors on the upper and lower surfaces of the airfoil; and This is a correction term for the trailing boundary conditions; For class functions, For the shape functions, their expressions are as follows: .

[0040] and The CST coefficients are the CST coefficients of the upper and lower surface curves, respectively. and middle, Bernstein function: .

[0041] n is a formal function The order.

[0042] S16: Based on the normalized spanwise coordinates of the wing Given the wing chord length, determine the X-coordinate of the normalized chord coordinate u on the wing in the local coordinate system.

[0043] Mapping the normalized coordinates to the real coordinates, and defining the origin of the local coordinate system as the leading edge of the wing, the X-coordinate of the normalized chordal coordinate u on the wing in the local coordinate system is: .

[0044] S17: Based on the normalized spanwise coordinates of the wing in the local coordinate system... The upper and lower surface curves of the airfoil at the cross-section, as well as the normalized spanwise coordinates of the wing, are as follows: The wing chord length is used to determine the altitude coordinates of the airfoil surface in the local coordinate system; the altitude coordinates of the airfoil surface in the local coordinate system include the altitude coordinates of the upper surface of the airfoil and the altitude coordinates of the lower surface of the airfoil in the local coordinate system.

[0045] The local upper and lower surface heights relative to the chord plane are: .

[0046] in, These are the height coordinates of the upper surface of the airfoil in the local coordinate system. These are the height coordinates of the lower surface of the airfoil in the local coordinate system.

[0047] S18: Normalize the spanwise coordinates of the wing in the local coordinate system as follows: Rotate the point with normalized chord coordinate u around the reference axis by the dihedral angle of the wing to determine the normalized spanwise coordinate of the wing in the local coordinate system. The normalized chord coordinates of a point with chord coordinate u are its chord coordinates, height coordinates, and span coordinates in the global coordinate system.

[0048] Considering the torsion about the wing's reference axis, the coordinates of a point on the wing relative to the reference axis are: .

[0049] in, The reference axis of the wing is located at a point on the wing, typically taken as 0.25. The local twist angle of the wing is the angle of rotation of a point on the wing around the reference axis. A schematic diagram of the partial twist angle of the wing is shown below. Figure 4 As shown, the normalized spanwise coordinates of the wing in the local coordinate system are: The normalized chord coordinates of a point with 'u' in the global coordinate system are: .

[0050] These are the height coordinates of the airfoil surface in the local coordinate system.

[0051] The normalized spanwise coordinates of the wing in the local coordinate system are The height coordinates of a point with normalized chordal coordinate u in the global coordinate system are: .

[0052] The normalized spanwise coordinates of the wing in the local coordinate system are The span coordinates of a point with normalized chord coordinate u in the global coordinate system are: .

[0053] S19: Based on the normalized spanwise coordinates of the wing in the local coordinate system, The normalized chord coordinates, altitude coordinates, and span coordinates of a point with chord coordinate u in the global coordinate system are used to determine the parametric geometric model of the outer surface of the wing.

[0054] In one embodiment, the parametric geometric model of the wing's outer surface is: .

[0055] It can also be expressed as: .

[0056] S2: Based on the unit normal vector of the parametric geometric model, the parametric geometric model is offset along the normal of the aerodynamic shape surface to obtain the initial wing leading edge core model geometric model.

[0057] In practical applications, a thickness-controllable normal offset mandrel geometric model based on an aerodynamic surface is established to generate a smooth and continuous three-dimensional woven mandrel shape. By transforming the normal offset of the aerodynamic surface into a manufacturable three-dimensional woven mandrel geometric framework, the controllable adjustment of the offset thickness is achieved, ensuring the smoothness and continuity of the mandrel surface after offset.

[0058] As an optional implementation, S2 specifically includes: S21: Based on the parametric geometric model, calculate the rate of change of coordinates in the chord direction and the rate of change of coordinates in the spanwise direction for any point on the wing.

[0059] In this embodiment, the wing geometry is offset in the normal direction to allow for the thickness of the three-dimensional woven prefabricated body. Based on the precise normal obtained from the wing parametric surface, the rate of change of coordinates in the chord and spanwise directions is first calculated for any point on the wing: .

[0060] in, The rate of change of the coordinates in the chord direction; This represents the rate of change of the coordinates in the span direction.

[0061] S22: Determine the outward normal direction vector based on the rate of change of the coordinates in the chord direction and the rate of change of the coordinates in the span direction.

[0062] The outward normal direction vector is: .

[0063] S23: Determine the unit normal vector of the parametric geometric model based on the outward normal direction vector.

[0064] The unit normal vector is: .

[0065] S24: Determine the normal offset based on the thickness of the three-dimensional woven preform and the assembly trimming allowance.

[0066] In practical applications, the thickness of the three-dimensional woven preform should be considered. Assembly trimming allowance Define the normal bias quantity : .

[0067] S25: Based on the unit normal vector, the parameterized geometric model is offset along the normal direction by a normal offset amount to obtain the initial wing leading edge core model geometric model.

[0068] In one embodiment, the initial wing leading edge mandrel geometry is as follows: .

[0069] S3: Symmetrically transform the wing leading edge region of the initial wing leading edge core geometric model along the plane of symmetry and make a smooth transition to form a closed wing leading edge core geometric model; the plane of symmetry is the plane perpendicular to the airfoil chord and the location of the wing leading edge plus the cutting and trimming allowance.

[0070] In this embodiment, the leading edge of the wing is the area on the wing most vulnerable to bird strikes. Compared to the wing surface skin, the leading edge should have additional impact resistance and energy absorption characteristics. Therefore, in the design, the leading edge skin of the wing is generally specially designed separately. This application selects... The range of values ​​is used to control the geometric features of the wing leading edge. The wing leading edge region is... ,in, , , At this point, the leading edge of the wing is an open structure that is not closed.

[0071] Define the airfoil chord The perpendicular plane containing the point is the plane of symmetry. To allow for trimming and cutting, the mandrel in the wing leading edge region is made symmetrical along the plane of symmetry. The edge points corresponding to the two open mandrels are then smoothly transitioned to obtain a closed wing leading edge mandrel geometric model, as shown below. Figure 5 As shown.

[0072] S4: Manufacture closed mandrel 1 according to the geometric model of the leading edge mandrel of the closed wing, such as... Figure 6 As shown. In practical applications, closed mandrel 1 is a continuous curved closed mandrel that corresponds to (maps) the shape of the wing and is suitable for the one-piece molding of three-dimensional braided composite materials. The purpose of manufacturing the closed mandrel is to obtain the leading edge structures of two wings in one step.

[0073] S5: Perform three-dimensional weaving around the closed core mold, and then demold and cut in sequence to obtain the three-dimensional woven wing leading edge preform; wherein, the three-dimensional weaving process parameters are obtained by solving the yarn path length factor based on the cross-sectional geometric parameters of the closed core mold along the spanwise direction; the cutting is performed on the surface of the closed core mold according to a preset space curve.

[0074] In practical applications, based on the cross-sectional geometric parameters of the closed mandrel along the span, the quantity of each yarn system and the weaving angle, and other process parameters, are solved by the yarn path length factor.

[0075] In one embodiment, the material of the closed mandrel is metal or high-strength plastic.

[0076] In one embodiment, the closed mandrel is manufactured using a solid machining method. The solid machining method employs conventional machining methods in the art, including but not limited to CNC milling, turning, or other commonly used machining methods. After the solid machining is completed, this application further includes surface treatment and dimensional inspection of the initial closed mandrel obtained from the solid machining to ensure that the geometric accuracy and surface finish of the manufactured closed mandrel meet the design requirements.

[0077] In one embodiment, the weaving method of the three-dimensional weaving is preferably three-dimensional and five-dimensional; the weaving angle is selectable. In this embodiment, the initial weaving angle is preferably... The volume content of the three-dimensional braided wing leading edge preform in the wing leading edge three-dimensional braided composite material is preferably 45%~60%, and in this embodiment, the initial volume content of the three-dimensional braided preform is preferably 50%. The process parameters for the three-dimensional braiding are determined according to the following steps: Step 1. Based on the geometric parameters of the closed mandrel, the normalized spanwise coordinates are... The cross-section, read the geometric quantities of the cross-section. and ,in, The perimeter of the core mold cross section is The minimum radius of curvature of the cross-section mandrel.

[0078] Step 2. Based on the wing leading edge performance requirements, select the design quantity: the target thickness of the three-dimensional braided wing leading edge prefabricated body at the cross-section. Fiber volume content of the three-dimensional braided wing leading edge preform Z-direction yarn bundle length factor , the first in the plane Initial weaving angle of the yarn bundle relative to the development direction ,in, .

[0079] The length factor is the actual length of the yarn per unit length along the axial direction (i.e., the span direction) when the yarn is wound obliquely around the mandrel. In three-dimensional five-directional weaving, one bundle of yarn (Z-axis yarn) runs along the axial direction, while the other four bundles of yarn form an angle with the axial direction, typically two sets of symmetrical angles. A schematic diagram of three-dimensional five-directional yarn is shown below. Figure 6 As shown in the upper right corner.

[0080] Step 3. According to , No. Yarn bundle length factor for: .

[0081] The volume of the composite material per unit span is: .

[0082] The total volume of the yarn bundle per unit span is: .

[0083] in, For the section number The number of yarn bundles along the circumference, For the first The cross-sectional area of ​​the yarn bundle. Then the fiber volume fraction at the leading edge of the three-dimensional braided wing is: .

[0084] Therefore, we can conclude that: .

[0085] Calculated from the above formula For the first The number of consecutive yarn bundles in the circumferential direction, rounded up to obtain the integer number of yarn bundles: .

[0086] Step 4. The actual fiber volume fraction is: .

[0087] The circumferential spacing of the fiber bundles is: .

[0088] Check the fiber volume content, yarn spacing, yarn curvature, and yarn bundle angle constraints. If the checks pass, proceed to step 6; otherwise, proceed to step 5 iteration.

[0089] .

[0090] .

[0091] .

[0092] .

[0093] in, This is the minimum yarn spacing. The minimum allowable bending radius for the yarn bundle. This is for the safety factor.

[0094] Step 5. Adjust the design quantity If the fiber volume content is too high, or the yarn bundle spacing is too small, increase the yarn bundle weaving angle; otherwise, decrease the yarn bundle weaving angle. When the angle reaches the design limit, adjust the cross-sectional area of ​​the yarn bundle. If the fiber volume content is too high, or the yarn bundle spacing is too small, increase the cross-sectional area of ​​the yarn bundle; otherwise, decrease the cross-sectional area of ​​the yarn bundle.

[0095] After adjusting the design quantities, proceed to step 3 for iterative calculations until the design requirements are met.

[0096] Step 6. For all normalized spanwise coordinates... The cross-section was calculated. and Spanning smoothing was performed to obtain the process parameters for the three-dimensional braided wing leading edge preform.

[0097] In one embodiment, after demolding, the material is cut and trimmed along the plane of symmetry to obtain two identical three-dimensional woven wing leading edge preforms.

[0098] In one exemplary embodiment, a three-dimensional braided composite material for the leading edge of a wing is provided, comprising a resin matrix and a reinforcing material, wherein the reinforcing material comprises the three-dimensional braided wing leading edge preform 2 described in the above-described technical solution. The reinforcing material is disposed within the resin matrix.

[0099] In one embodiment, the reinforcing material further includes an energy-absorbing layer 4 and an energy-absorbing layer capping layer 5, wherein the three-dimensional woven wing leading edge preform 2, the energy-absorbing layer 4, and the energy-absorbing layer capping layer 5 are stacked sequentially.

[0100] In one exemplary embodiment, such as Figure 7 As shown, a method for preparing the three-dimensional braided composite material for the leading edge of the wing described above is provided. The reinforcing material is placed in a curing mold and cured by resin transfer molding (RTM) to obtain the three-dimensional braided composite material for the leading edge of the wing.

[0101] In one embodiment, the curing mold includes an outer curing mold 6 and an inner curing mold 7. The geometry of the outer curing mold 4 is determined by the parametric geometric model of the wing's outer surface in step S1. Control, among which and The values ​​are the same as those of the geometric model of the leading edge core mold of the closed wing in step S3.

[0102] In one embodiment, the reinforcing material is placed in a curing outer mold 6 and then subjected to RTM curing, which is a generally accepted method in the field.

[0103] The method for determining the geometric model of the wing leading edge mandrel, the method for preparing the three-dimensional braided wing leading edge preform, and the three-dimensional braided wing leading edge composite material and its preparation method disclosed in this application have the following advantages: 1. Three-dimensional braided composite materials provide continuous fiber reinforcement, avoiding the delamination and cracking problems of traditional two-dimensional laminated composite materials, resulting in better overall strength and damage resistance.

[0104] 2. Through parametric modeling, this application can be applied to the leading edge of an airfoil with variable cross-section characteristics. Combined with three-dimensional weaving technology, near-net-shape forming of complex geometric leading edges can be achieved. The resulting preform is highly consistent with the geometry of the target airfoil leading edge, thereby avoiding the complex process of traditional secondary forming and improving the forming accuracy of the airfoil leading edge skin.

[0105] 3. By symmetrically closing the semi-open leading edge geometry of the wing to form a completely closed mandrel structure, three-dimensional weaving is then performed on this mandrel. After demolding, the woven part is cut along symmetrical positions, allowing two identical wing leading edge composite material parts to be obtained simultaneously. This method can produce two finished products in a single weaving process, reducing repetitive steps and significantly improving molding and manufacturing efficiency.

[0106] 4. The core mold is generated using parametric formulas based on the wing geometry, avoiding errors caused by relying on manual drawing and experience-based modeling. Describing the airfoil and wing geometry through unified mathematical expressions ensures the standardization and repeatability of the core mold design process, thereby guaranteeing geometric consistency across different batches of finished products. Furthermore, this method facilitates rapid modification and expansion based on design parameters, improving flexibility in product iteration and engineering applications.

[0107] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0108] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for fabricating a three-dimensional woven wing leading edge preform based on parametric modeling, characterized in that, include: Based on the wing design parameters, a parametric geometric model of the wing's outer surface is constructed using the CST parametric method; Based on the unit normal vector of the parametric geometric model, the parametric geometric model is offset along the normal of the aerodynamic shape surface to obtain the initial wing leading edge core model geometric model. The wing leading edge region of the initial wing leading edge mandrel geometric model is symmetrical along the plane of symmetry and smoothly transitioned to form a closed wing leading edge mandrel geometric model; the plane of symmetry is the plane perpendicular to the airfoil chord line where the wing leading edge plus the cutting and trimming allowance is located; Manufacture a closed core mold based on the geometric model of the leading edge core mold of the closed wing; The closed mandrel is woven in three dimensions, and then demolded and cut in sequence to obtain a three-dimensional woven wing leading edge preform. The three-dimensional weaving process parameters are obtained by solving the yarn path length factor based on the cross-sectional geometric parameters of the closed mandrel along the spanwise direction. The cutting is carried out on the surface of the closed mandrel according to a preset space curve.

2. The method for preparing a three-dimensional braided wing leading edge preform based on parametric modeling according to claim 1, characterized in that, The wing design parameters include wing span, wing leading edge sweep angle, wing dihedral angle, wing reference axis, wing chord length at any spanwise position, and wing local twist angle at any spanwise position.

3. The method for preparing a three-dimensional woven wing leading edge preform based on parametric modeling according to claim 2, characterized in that, Based on the wing design parameters, a parametric geometric model of the wing's outer surface is constructed, specifically including: Based on the stated wing span, the normalized spanwise coordinates on the wing are determined as follows: The airfoil section in the global coordinate system coordinate; Based on the normalized spanwise coordinates of the wing The airfoil section in the global coordinate system Using the coordinates and the sweep angle of the wing leading edge, determine the airfoil leading edge point in the global coordinate system. coordinate; Based on the normalized spanwise coordinates of the wing The airfoil section chord length and the airfoil leading edge point in the global coordinate system Coordinates, determining the reference axis in the global coordinate system coordinate; Based on the normalized spanwise coordinates of the wing The airfoil section in the global coordinate system Using coordinates and the dihedral angle of the wing, determine the reference axis in the global coordinate system. coordinate; Using the shape function transformation method, the normalized spanwise coordinates of the wing in the local coordinate system are determined as follows: The upper and lower surface curves of the airfoil at the cross-section; Based on the normalized spanwise coordinates of the wing The wing chord length is used to determine the X-coordinate of the normalized chord coordinate u on the wing in the local coordinate system; Based on the normalized spanwise coordinates of the wing in the local coordinate system: The upper and lower surface curves of the airfoil at the cross-section, as well as the normalized spanwise coordinates of the wing, are as follows: The wing chord length determines the altitude coordinates of the airfoil surface in the local coordinate system; the altitude coordinates of the airfoil surface in the local coordinate system include the altitude coordinates of the upper surface of the airfoil and the altitude coordinates of the lower surface of the airfoil in the local coordinate system. The normalized spanwise coordinates of the wing in the local coordinate system are: The point with normalized chord coordinate u is rotated about the reference axis by the local twist angle of the wing. The normalized spanwise coordinate of the wing in the local coordinate system is then determined. The normalized chord coordinates, height coordinates, and span coordinates of a point with chord coordinate u in the global coordinate system; Based on the normalized spanwise coordinates of the wing in the local coordinate system: The normalized chord coordinates, altitude coordinates, and span coordinates of a point with chord coordinate u in the global coordinate system are used to determine the parametric geometric model of the outer surface of the wing.

4. The method for preparing a three-dimensional woven wing leading edge preform based on parametric modeling according to claim 3, characterized in that, The parametric geometric model of the outer surface of the wing is as follows: ； in, The normalized spanwise coordinates of the wing in the local coordinate system are: The normalized chord coordinates of a point with chord coordinate u in the global coordinate system; The normalized spanwise coordinates of the wing in the local coordinate system are: The span coordinates of a point with normalized chord coordinate u in the global coordinate system; The normalized spanwise coordinates of the wing in the local coordinate system are: The height coordinates of a point with normalized chordal coordinate u in the global coordinate system.

5. The method for preparing a three-dimensional braided wing leading edge preform based on parametric modeling according to claim 1, characterized in that, Based on the unit normal vector of the parametric geometric model, the parametric geometric model is offset along the normal direction to obtain the initial wing leading edge core model geometric model, specifically including: Based on the parametric geometric model, the rate of change of coordinates in the chord direction and the rate of change of coordinates in the spanwise direction are calculated for any point on the wing; The outward normal direction vector is determined based on the rate of change of the coordinates in the chord direction and the rate of change of the coordinates in the span direction; Determine the unit normal vector of the parametric geometric model based on the outward normal direction vector; The normal offset is determined based on the thickness of the three-dimensional woven preform and the assembly trimming allowance. Based on the unit normal vector, the parameterized geometric model is offset by a normal offset along the normal direction into the wing interior to obtain the initial wing leading edge core geometric model.

6. The method for preparing a three-dimensional braided wing leading edge preform based on parametric modeling according to claim 5, characterized in that, The initial wing leading edge core geometry is as follows: ； in, A parametric geometric model of the wing's outer surface; This refers to the normal offset of the parametric geometric model; This is the unit normal vector of the parametric geometric model.

7. The method for preparing a three-dimensional braided wing leading edge preform based on parametric modeling according to claim 1, characterized in that, The leading edge area of ​​the wing is ;in, , ,and .

8. A three-dimensional braided composite material for the leading edge of an airfoil, characterized in that, It includes a resin matrix and a reinforcing material, wherein the reinforcing material includes the three-dimensional braided wing leading edge preform as described in any one of claims 1-7.

9. The three-dimensional braided composite material for the leading edge of a wing according to claim 8, characterized in that, The reinforcing material also includes an energy-absorbing layer and an energy-absorbing layer capping layer, wherein the three-dimensional woven wing leading edge preform, the energy-absorbing layer, and the energy-absorbing layer capping layer are stacked sequentially.

10. The method for preparing the three-dimensional braided composite material for the leading edge of a wing as described in claim 8 or 9, characterized in that, The reinforcing material is placed in a curing mold and resin transfer molding is performed to obtain the three-dimensional woven composite material of the wing leading edge.

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