Topology flattening method for three-dimensional woven composite material part

Abstract

The three-dimensional woven composite material piece topology flattening method for designing the twisted blade comprises the following steps that S1, a twisted curved surface is extracted from the twisted blade, two-dimensional twisted grids are designed on the twisted curved surface, and coordinates of intersection points of all the twisted grids corresponding to all the positions on the twisted curved surface are obtained; s2, obtaining the thickness data of the distance between the intersection point of each bending and twisting grid and the pressure surface and / or the suction surface of the blade; s3, converting the torsion curved surface into a two-dimensional flattened feature surface, and generating a two-dimensional grid for the two-dimensional design surface to obtain a two-dimensional coordinate; and S4, coordinates of intersection points of the bending and twisting grids are converted into two-dimensional coordinates in the two-dimensional grids, and the two-dimensional coordinates are endowed with the thickness data obtained in the step S2. According to the method, the topological flattening problem of the three-dimensional woven composite material bending and twisting blade is solved, the designed shape of the three-dimensional woven composite material fan blade is converted into a flat-plate-like model which can be realized on a knitting machine, and the design precision is effectively improved.

Description

Technical Field

[0001] The present invention relates to the field of aeroengines, and particularly to the field of three-dimensional woven composites. Background Art

[0002] The forming process of three-dimensional woven composites is as follows: using a loom to weave fiber bundles into a preform flat plate, cutting the preform flat plate and laying it in a mold, using an RTM injection device to inject resin into the closed mold, the resin infiltrating the preform in the entire mold cavity, curing, and demolding to form.

[0003] RTM is a most mature high-performance composite liquid forming process, which can produce parts with extremely high precision and good mechanical properties. During the RTM process, the preform is placed in a mating mold with high stiffness, and the liquid resin is injected into the mold under pressure, and then the part is cured in the mold. During this process, usually the fibers of the preform are distorted and worn, and its in-plane mechanical properties will be lower than those of unidirectional tape products. Especially for preforms with large deflection and large deformation and two-way variable thickness, such as fan blade preforms and other components with a large degree of torsion, the thickness at each point is continuously changing, and the woven structure parameters are also different, and non-uniform loads are applied in the mold, resulting in deformations such as compaction, bending and torsion, so that the design accuracy of the molded woven composite parts decreases. Therefore, in the research and development, it is necessary to focus on the design and manufacture of composite parts with torsional characteristics.

[0004] The prior art generally cannot directly perform the topological structure conversion of three-dimensional woven composite blades preforms. A commonly used method is to process the fibers / fiber bundles in a fine or equivalent simplified manner for three-dimensional woven preforms. This not only depends on a computer for modeling, but also is limited to the level of materials and small-sized components. If a fine model is constructed for three-dimensional woven composite parts, it will lead to an excessive workload, and the computer hardware and calculation time are both unacceptable. Another method is to establish the large deformation constitutive of the fabric through simple three-dimensional fabric tests. However, the current large deformation constitutive model of the fabric has a large error from the actual test, generally more than 20%, and is usually only used for qualitative analysis of trends such as deformation. The error accumulation and result deviation caused by using such a material constitutive to predict macroscopic parts and perform topological conversion are unacceptable. Summary of the Invention

[0005] An object of the present invention is to provide a method for topological flattening of three-dimensional woven composite parts, in order to achieve high-precision and high-efficiency design of three-dimensional woven composites.

[0006] The three-dimensional woven composite part topological flattening method for achieving the above object is used to design a curved and twisted blade, and includes the following steps: S1. Extract a twisted surface from the curved and twisted blade, design a two-dimensional curved and twisted grid on the twisted surface, and obtain the coordinates of each intersection point of the curved and twisted grid corresponding to each position on the twisted surface; S2. Obtain the thickness data of each intersection point of the curved and twisted grid from the pressure surface and / or suction surface of the blade; S3. Convert the twisted surface into a two-dimensional flattened feature surface, generate a two-dimensional grid for the two-dimensional design surface, and obtain two-dimensional coordinates; S4. Convert the coordinates of each intersection point of the curved and twisted grid into two-dimensional coordinates within the two-dimensional grid, and assign the thickness data obtained in S2 to the two-dimensional coordinates.

[0007] In one or more embodiments, in step S1, the mid-plane or the film-attached surface or the positioning surface of the twisted blade is used as the twisted surface.

[0008] In one or more embodiments, in step S2, extract the distance data from each row of grid nodes along the blade height direction on the twisted surface to the pressure surface and / or suction surface.

[0009] In one or more embodiments, the method further includes step S5. Generate a modeling curve according to all two-dimensional coordinates, and generate a blade flat plate according to the modeling curve.

[0010] In one or more embodiments, the method further includes step S6. Use the two-dimensional grid to obtain the positioning line for forming.

[0011] In one or more embodiments, the twisted blade includes a blade body and a tenon. The blade body and the tenon are respectively obtained with partitioned two-dimensional flattened feature surfaces according to steps S1-S4, and then stitched through the boundary line between the blade body and the tenon.

[0012] In one or more embodiments, in step S2, the thickness value from each intersection point to the pressure surface is defined as a positive value, and the thickness value from each intersection point to the suction surface is defined as a negative value.

[0013] The above-mentioned topological flattening method for three-dimensional woven composite parts is aimed at bending-twisting blades with complex aerodynamic surface characteristics such as large sweep, large aspect ratio, and variable thickness. It adopts a two-dimensional flattening method to flatten the three-dimensional woven composite blade into two dimensions. Through the corresponding transformation of the intersection coordinates of the bending-twisting grid and the two-dimensional coordinates, the positions of each point on the bending-twisting surface of the blade are accurately located. By assigning the thickness data to the two-dimensional coordinates, each point on the bending-twisting surface matches the corresponding thickness, so as to convert the complex designed shape of the three-dimensional woven composite bending-twisting blade into a flat-plate-like model that can be realized on a knitting machine, and obtain a preform that meets expectations. After being molded by pressing, this preform can obtain a molded blade with better accuracy according to the expected deformation. Moreover, compared with the large-scale modeling method, the above method has a smaller calculation amount on the premise of ensuring accuracy, meeting the requirements of engineering practical applications. Brief Description of the Drawings

[0014] The above and other features, properties and advantages of the present invention will become more obvious through the following description in conjunction with the drawings and embodiments, where:

[0015] Figure 1A is a schematic structural diagram of a bending-twisting blade;

[0016] Figure 1B is a schematic diagram of the flattened blade;

[0017] Figure 2 is a schematic diagram of a two-dimensional bending-twisting grid;

[0018] Figure 3 is a schematic diagram of the thickness relationship between the intersection of the bending-twisting grid and the pressure surface and / or suction surface of the blade;

[0019] Figure 4 is a front view of the two-dimensional grid of the two-dimensional flattened characteristic surface;

[0020] Figure 5 is a flowchart of the topological flattening method for three-dimensional woven composite parts;

[0021] Figure 6 is a specific flowchart of an embodiment of the topological flattening method for three-dimensional woven composite blades. Detailed Embodiments

[0022] The present invention will be further described below in conjunction with specific embodiments and drawings. More details are elaborated in the following description to facilitate a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from this description. Those skilled in the art can make similar generalizations and deductions according to the actual application situation without departing from the connotation of the present invention. Therefore, the protection scope of the present invention should not be limited by the content of this specific embodiment.

[0023] It should be noted that these and subsequent other drawings are only examples, and they are not drawn under the condition of equal proportion, and should not be used to limit the actual scope of protection required by the present invention.

[0024] For a bent and twisted blade with complex aerodynamic surface features such as large bend sweep, large aspect ratio, variable thickness, etc. as shown in Figure 1A If it is formed by three-dimensional woven composite materials, the thickness at multiple points on the blade is likely to undergo unexpected deformation during the manufacturing process, affecting the accuracy of the blade. Therefore, it is required to focus on the accuracy of each point during the design stage to avoid the situation where the thickness at each point on the three-dimensional woven composite material component does not meet the requirements.

[0025] The three-dimensional woven composite material part topology flattening method described in the present invention can obtain a flat plate-like model that can be realized on a weaving machine and has high precision by flattening the torsion surface on the bent and twisted blade, obtaining accurate point-to-point corresponding coordinates between the bent and twisted grid and the two-dimensional grid, and calculating the thickness data of each point, thereby effectively improving the accuracy during the design process.

[0026] This three-dimensional woven composite material part topology flattening method is understood with reference to the Figure 5 flow chart shown. It should be noted that the numbers and serial numbers before each step only serve as a description and do not necessarily constitute a limitation on the order of the operation steps of this method.

[0027] This method includes the following steps: S1. Extract the torsion surface of the rotating and twisting component, design a two-dimensional bent and twisted grid on the torsion surface, and obtain the coordinates of each intersection point of the bent and twisted grid corresponding to each position on the torsion surface; S2. Obtain the thickness data of each intersection point of the bent and twisted grid from the pressure surface and / or suction surface of the blade; S3. Convert the torsion surface into a two-dimensional flattened feature surface, and generate a two-dimensional grid on the two-dimensional flattened feature surface; S4. Convert the coordinates of each intersection point of the bent and twisted grid into two-dimensional coordinates within the two-dimensional grid, and assign the thickness data obtained in S2 to the two-dimensional coordinates.

[0028] In some embodiments, it further includes step S5, generating a modeling curve P according to all two-dimensional coordinates, and generating a flat plate-like model of the blade according to all the modeling curves P.

[0029] Specifically, in step S1, it is necessary to first identify the blade deformation characteristics, and use the thickness and the position of the deformation trend as the flattening reference, generally in the tenon area.

[0030] Establish an axis spanwise coordinate axis, and perform manufacturability analysis on the feature design layer. Extract a torsion surface from the bent and twisted state design model of the blade as the design feature surface in the first step, such as using the middle surface, or the film pasting surface, or the positioning surface of the twisted blade as the torsion surface. The middle surface refers to a layer of surface with a thickness in the middle of the blade, such as Figure 2The plane indicated by the middle C line.

[0031] Preferably, the selected range of the design feature surface should exclude the non-deformable areas on the blade to ensure deformation coordination. After determining the torsion surface, a two-dimensional curved and twisted grid M as shown in Figure 2 is established. That is, this grid has two dimensions, transverse and longitudinal, but it is a grid on the curved and twisted surface. For example, if two dimensions of the blade axis direction and the blade radial direction are taken and defined as the u-direction and the v-direction respectively, then each point position on the torsion surface is marked through the two-dimensional curved and twisted grid, and each position A can be expressed as the coordinates of the intersection point on the two-dimensional curved and twisted grid, such as the node (u M , v M ).

[0032] In some embodiments, the grid points on the torsion surface are partitioned according to the blade profile curvature analysis results, and then the grids within each partition are equally divided. The area below 30% of the blade height is subjected to grid densification, and the number of densified grids is 3 / 2 to 4 / 3 times the number of non-densified grids.

[0033] Specifically, the number of grid density seeds in the spanwise direction is not less than 60, and the number of chordwise grid seeds is not less than 40.

[0034] It should be noted that the extracted torsion surface in this application has a thickness value Z. For example, the thickness value on the middle surface C of the selected blade is half of the overall thickness of the blade.

[0035] In step S2, the distance data t from each row of grid nodes along the blade height direction on the torsion surface to the pressure surface 12 and / or the suction surface 11 is extracted. For example, the spatial distances from each node to the pressure surface 12 and the suction surface 11 are calculated respectively, and are considered as the equivalent thicknesses t1 and t2.

[0036] In some embodiments, the thickness value from each intersection point to the pressure surface 12 is defined as a positive value, and the thickness value to the suction surface 11 is defined as a negative value. After exporting the node information, at this time, the position of each node A on the blade and the distance data t1 and t2 from the pressure surface and / or the suction surface are recorded, and each node has two-dimensional position data and thickness data (u M , v M , t), where the sum of the thickness data and the current position is the true thickness at this position of the torsion surface.

[0037] The above operations are performed on all intersection points of the torsion surface.

[0038] Subsequently, a topological flattening process is carried out. Referring to Figure 1A and Figure 1B , Figure 4 it is understood that the torsion surface is transformed into a two-dimensional flattened feature surface, and a two-dimensional grid is generated on the two-dimensional flattened feature surface. Each point position on the two-dimensional grid has two-dimensional coordinates B(uN ,v N ,), the coordinates are used for thickness positioning and blade plate modeling point generation in the subsequent design process.

[0039] After flattening, the bending and twisting shape of the three-dimensional woven composite fan blade design is converted into a flat-plate model that can be realized on a weaving machine. By combining the mature fabric constitutive flattening feature surface and using isoparametric correspondence to consider the three-dimensional thickness effect, this type of flat-plate model can meet the dual requirements of the anisotropic contour curve and variable thickness distribution of the blade plate entering the mold, with high mold closing accuracy.

[0040] The bending and torsion surface is flattened based on the verified fabric constitutive model, and the verified self-compiled two-dimensional fabric constitutive model can be used for inversion, or the two-dimensional fabric is flattened through verified commercial software such as Fibersim, PAM-Distortion, Catia, etc. After obtaining the two-dimensional grid and the two-dimensional bending and torsion grid and the thickness data of each bending and torsion grid intersection from the pressure surface and / or suction surface of the blade, the conversion step S4 is performed, that is, the coordinates of each bending and torsion grid intersection are converted into two-dimensional coordinates in the two-dimensional grid, and the thickness data obtained in S2 are assigned to the two-dimensional coordinates.

[0041] At this time, therefore, extract the (u M ,v M ) coordinates are converted into the coordinates of each point on the flattened two-dimensional feature surface according to the transformation relationship (u N ,v N ,), at this time, the coordinates of each point on the two-dimensional feature surface (u N ,v N ,) and the coordinates of the intersection point on the two-dimensional bending and torsion grid (u M ,v M ) is consistent with the position represented by . Since the assigned thickness data t1 and t2 are constants, the original thickness value Z of the extracted blade torsion surface is added and subtracted from the corresponding thickness values ​​t1 and t2, respectively, to obtain the thickness values ​​characterized by the positions of the blade suction surface and pressure surface in the two-dimensional coordinate system.

[0042] In addition, in some embodiments, the blade body and the tenon of the twisted blade are processed by partitioning: the blade body and the tenon are respectively subjected to steps S1-S4 to obtain the two-dimensional flattened characteristic surfaces of the partitions, and then stitched through the boundary line between the blade body and the tenon. The boundary line between the tenon and the blade body is extracted, and the suction surface and pressure surface of the blade plate are shaped by the curve group and stitched with the tenon, thereby completing the overall topological structure conversion of the woven composite material bending and twisting blade.

[0043] The generated topological points successively form a shaped curve and a blade flat plate. By the above method of expanding two-dimensional fabric conversion and using the isoparametric correspondence relationship to associate the flattened model with the design model, this method can ensure that the contour and thickness of the flattened blade flat plate model after conversion are consistent with those of the design model.

[0044] In some embodiments, the method further includes step S6. Using a two-dimensional grid to obtain the positioning lines used in the subsequent forming process for subsequent cooperation with the mold.

[0045] The above method generates a blade flat plate for three-dimensional woven design by assigning all two-dimensional coordinate points. Considering the deformation characteristics of three-dimensional woven composites, it reflects the three-dimensional effects of macroscopic components and the internal fabric deformation mechanism. In this way, the correspondence relationship between the thickness of the bent-twisted blade and the flattened blade is positioned through the grid points on the twisted surface and the flattened surface. The positions of the twisted surfaces corresponding to each two-dimensional point in the blade flat plate are accurate, and each two-dimensional point has accurate blade thickness information, thus converting the complex designed shape of the three-dimensional woven composite bent-twisted blade into a flat-plate-like model that can be realized on a knitting machine.

[0046] By combining the flattened characteristic surface of the mature fabric constitutive and considering the three-dimensional thickness effect using isoparametric correspondence, the designed three-dimensional woven composite bent-twisted blade will not have problems such as thickness mismatch and thickness misalignment in specific areas. Therefore, it has a high design accuracy and can meet the mold closing / molding accuracy requirements.

[0047] Next, according to Figure 6 the flowchart shown, a specific implementation manner of the method of the present invention will be described.

[0048] First, perform step S101 to extract the original blade characteristic surface (twisted surface), such as the mid-surface, film-attached surface, or positioning surface. Perform step S102 to set isoparametric lines on the characteristic surface to form intersection points A(u M ,v M ) to form a bent-twisted grid; then perform step S103 to set parameter points such as the blade basin and blade back to obtain the characteristics on the pressure surface and suction surface; finally, perform step S104 to obtain the distances from each parameter point on the characteristic surface to the corresponding points on the blade basin and blade back, that is, the equivalent thicknesses t1 and t2.

[0049] At the same time, perform the flattening process of the blade. In step S201, flatten the original blade characteristic surface into a two-dimensional flattened characteristic surface according to the two-dimensional fabric constitutive, and continue to perform step S202 to set isoparametric lines on the two-dimensional flattened characteristic surface to form intersection points B(u N ,v N ,) to obtain two-dimensional coordinates. Continue to perform step S203 to assign the equivalent thicknesses t1 and t2 calculated in step S104 to B(u N ,v N, ) Generate the points on the flattened blade basin and back, that is, obtain the points on the pressure surface and suction surface; then perform step S204 to generate a surface from the points and generate a surface from the curves. If the blade is partitioned, step S205 also needs to be performed to connect the tenons to complete the conversion of the topological structure. End the topological flattening process.

[0050] The above method does not need to reproduce all internal details and perform fine modeling, so it requires less computational effort and has a shorter iteration cycle.

[0051] This application uses specific terms to describe the embodiments of this application. For example, "one embodiment", "an embodiment", and / or "some embodiments" mean a certain feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that the "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more at different positions in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application can be appropriately combined.

[0052] Although the present invention is disclosed above in preferred embodiments, it is not used to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention all fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for topological flattening of three-dimensional woven composite parts, used for designing curved and twisted blades, Characterized in that, It includes the following steps: S1. Extract the twisted surface of the curved and twisted blade, design a two-dimensional curved and twisted grid on the twisted surface, and obtain the coordinates of each intersection point of the curved and twisted grid corresponding to each position on the twisted surface; S2. Obtain the thickness data of each intersection point of the curved and twisted grid from the pressure surface and / or suction surface of the blade; S3. Convert the twisted surface into a two-dimensional flattened feature surface, generate a two-dimensional grid on the two-dimensional design surface, and obtain two-dimensional coordinates; S4. Convert the coordinates of each intersection point of the curved and twisted grid into two-dimensional coordinates within the two-dimensional grid, and assign the thickness data obtained in S2 to the two-dimensional coordinates.

2. The method for topological flattening of three-dimensional woven composite parts according to claim 1, Characterized in that, In step S1, the middle surface or the film-attached surface or the positioning surface of the twisted blade is used as the twisted surface.

3. The method for topological flattening of three-dimensional woven composite parts according to claim 1, Characterized in that, The selected range of the twisted surface excludes the non-deformable area.

4. The method for topological flattening of three-dimensional woven composite parts according to claim 1, Characterized in that, In step S2, extract the distance data from each row of grid nodes along the blade height direction on the twisted surface to the pressure surface and / or suction surface.

5. The method for topological flattening of three-dimensional woven composite parts according to claim 1, Characterized in that, This method further includes step S5. Generate a modeling curve according to all two-dimensional coordinates, and generate a flat-plate-like model of the blade according to the modeling curve.

6. The method for topological flattening of three-dimensional woven composite parts according to claim 5, Characterized in that, This method further includes step S6. Use the two-dimensional grid to obtain the positioning line for forming.

7. The method for topological flattening of three-dimensional woven composite parts according to claim 1, Characterized in that, The twisted blade includes a blade body and a tenon. The blade body and the tenon are respectively obtained with partitioned two-dimensional flattened feature surfaces according to steps S1-S4, and then stitched through the dividing line between the blade body and the tenon.

8. The method for topological flattening of three-dimensional woven composite parts according to claim 7, Characterized in that, At least part of the grid points of the two-dimensional flattened feature surfaces of the blade body and the tenon close to each other overlap.

9. The method for topological flattening of three-dimensional woven composite parts according to claim 1, Characterized in that, The grid points on the twisted surface are partitioned according to the analysis result of the blade profile curvature.

10. The method for topological flattening of three-dimensional woven composite parts according to claim 9, Characterized in that, The area below 30% of the blade height is subjected to grid densification treatment.

11. The method for topological flattening of three-dimensional woven composite parts according to claim 10, Characterized in that, The number of densified grids is 3 / 2 to 4 / 3 times the number of non-densified grids.

12. The method for topological flattening of three-dimensional woven composite parts according to claim 10, Characterized in that, The number of grid density seeds in the spanwise direction is not less than 60, and the number of chordwise grid seeds is not less than 40.

13. The method for topological flattening of a three-dimensional woven composite part as claimed in claim 9, characterized in that, the grids within each partition are equally divided.

14. The method for topological flattening of a three-dimensional woven composite part as claimed in claim 1, characterized in that, in step S2, the thickness value from each intersection point to the pressure surface is defined as a positive value, and the thickness value from each intersection point to the suction surface is defined as a negative value.

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