A fiber-reinforced composite 3D printer wing based on Voronoi and its design method

Abstract

The present invention discloses a fiber-reinforced composite 3D printer wing based on Voronoi and a design method thereof. The wing is mainly composed of an outer contour and a frame structure inside the contour. The frame structure is composed of a group of initial sites in a region, which are constructed by constructing a Voronoi structure and performing centroid processing and proportional mapping to obtain a plurality of mapped Thiessen polygons. The outer contour is wrapped by a skin, and the frame structure is connected to the inner surface of the skin. The frame structure fills the entire wing. Under the premise of ensuring the load-bearing capacity, the fiber printing path of the frame structure is reasonably planned to achieve integrated molding and manufacturing of the composite wing. The present invention provides a composite wing structure with a simple structure, strong load-bearing capacity, good stability, and can be integrally molded by fiber-reinforced printing technology, thereby reducing the manufacturing time and production cost of the composite wing.

Description

Technical Field

[0001] The present invention belongs to the technical field of additive manufacturing of aviation equipment, and specifically relates to a Voronoi-based fiber-reinforced composite 3D printer wing and a design method thereof. Background Art

[0002] With the rapid development of the aerospace industry, the demand for and application of drones is also increasing. As an important component of drones, wings have become a key research topic requiring focused attention on how to ensure good load-bearing performance while ensuring quality. The application of composite materials on wings is undoubtedly an effective means and measure. In addition to being lightweight, composite materials also have excellent mechanical properties, designability, corrosion resistance, and other advantages. However, traditional composite wing structures are mostly composed of components such as spars, longitudinal walls, stringers, and ribs. In terms of form, this type of wing structure mainly consists of skeletons distributed along the longitudinal direction (span direction), such as spars, longitudinal walls, and stringers, and skeletons distributed along the transverse direction (along the airflow direction perpendicular to the spars), such as ribs. These vertically and horizontally distributed skeleton structures are interconnected inside the wing, and there are a large number of connection structures such as bolts and rivets at the joints, which makes the internal support structure complex and intertwined. Although this type of structure can have a good load-bearing capacity while ensuring quality, it is limited by its structure and cannot be prepared through traditional composite material manufacturing processes through integrated molding. The molding process often requires the assistance of multiple steps and corresponding post-processing. Sometimes, specific molds need to be prefabricated, which results in a long molding cycle and high manufacturing costs. Summary of the Invention

[0003] The present invention aims to overcome the shortcomings of the prior art by providing a Voronoi-based fiber-reinforced composite 3D-printed wing and its design method. This approach addresses the existing problems of composite wing structures, such as the numerous connectors, difficulty in integrated molding, and complex manufacturing processes. This wing structure not only meets the load-bearing requirements of the wing but also enables fiber-reinforced, integrated molding, thereby improving manufacturing efficiency and reducing costs.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A fiber-reinforced composite 3D printed wing based on Voronoi is characterized in that it includes an outer contour, a frame structure is arranged inside the outer contour, the frame structure is composed of a plurality of Thiessen polygons, the outside of the outer contour is wrapped by a skin, and the frame structure is connected to the inner surface of the skin.

[0006] A further improvement of the present invention is:

[0007] Preferably, the outer contour and the frame structure are made of the same material, the matrix of the material is a thermoplastic material, and the reinforcement is continuous fiber.

[0008] Preferably, the frame structure has the same structural form at any cross section along the wing span.

[0009] Preferably, each Thiessen polygon is provided with a diagonal bracing portion, and upper and lower adjacent Thiessen polygons share the diagonal bracing portion.

[0010] Preferably, the frame structure is prepared by 3D printing, and the printing path during the printing process is a continuous path.

[0011] Preferably, in a continuous path, the outer contour of the wing is printed first, and then the frame structure of the wing;

[0012] The 3D printing is a fiber printing process.

[0013] A method for designing a fiber-reinforced composite 3D printer wing based on Voronoi comprises the following steps:

[0014] Step 1: Draw the outer contour of the wing and determine the chord length of the wing;

[0015] Step 2: Create a closed surface enclosed by the outer contour, and determine the average width of the wing through the surface area and chord length of the closed surface;

[0016] Step 3, generate a rectangle by chord length and average width;

[0017] Step 4: randomly generate n sites in the rectangular area, generate Thiessen polygons around each site, and move the site to the centroid of the Thiessen polygon where the site is located using the Lloyd algorithm to generate uniform and stable Thiessen polygons;

[0018] Step 5: Extract the coordinates of n sites in multiple stable Thiessen polygons, map the coordinates of the n sites to the outer contour of the wing, obtain the coordinate values ​​of the new n sites in the outer contour line of the wing, and generate multiple mapped Thiessen polygons in the outer contour of the wing through the coordinate values ​​of the n sites. All the mapped Thiessen polygons form a frame structure to complete the design of the 3D printed wing.

[0019] Preferably, in step 2, the average width is obtained by dividing the curved surface area of ​​the wing by the chord length of the wing.

[0020] Preferably, in step 4, after connecting adjacent sites in pairs, multiple Delaunay triangles are obtained according to the standard of Delaunay triangles, and multiple Thiessen polygon graphics are generated through the Delaunay triangles.

[0021] Preferably, in step 5, the site coordinate information of all Thiessen polygons is extracted and mapped to the coordinate system of the outer contour of the wing. For any coordinate point (x i ,y i ), the mapped coordinate point is (x i ',y i '), x i '=x i ,y i '=b1*y i / y, b1 is x ’ The wing width corresponding to the horizontal coordinate.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This invention discloses a fiber-reinforced composite 3D-printed wing based on Voronoi. The main structure of this printed wing is a set of Thiessen polygons within the wing. To address the difficulty of integrated molding and processing of traditional beam-rib wing structures, a wing structure based on centroided Voronoi representation is designed. This structure fills the entire wing interior and is essentially evenly distributed along the chord length and connected to the upper and lower panels of the wing skin, thereby providing good load-bearing performance while ensuring quality. The wing structure also includes corresponding diagonal braces to facilitate load transfer. The designed wing structure is inspired by the dragonfly wing found in nature. Observation of the dragonfly wing structure reveals the presence of numerous uniformly shaped Thiessen polygon units within the structure, which maintains its flight stability. The present invention proposes a new wing structure based on the wing structure of a dragonfly, which is a bionic wing structure. This structure not only improves the load-bearing characteristics to meet the corresponding load-bearing characteristics of the wing, but also takes into account the process characteristics of integrated processing and molding. At the same time, it can realize the integrated processing and molding of the structure through a continuous fiber manufacturing process, and does not require assembly and gluing, thereby improving the manufacturing efficiency of the fiber wing and reducing the manufacturing cost.

[0024] Furthermore, since the wing structure can be manufactured through an integrated molding process, the number of parts is greatly reduced compared to traditional composite beam-rib wing support structures, making it easier to manufacture and maintain, thereby realizing rapid and low-cost integrated manufacturing of fiber-reinforced integrated molding 3D printed lightweight wing structures.

[0025] Furthermore, compared with traditional wing structures, it has the following advantages:

[0026] 1) The structure is very compact, that is, the number of variables required to describe the structure is limited, reducing the workload of parameterization;

[0027] 2) The parameterization is stable (under relatively general conditions), that is, small changes in the coordinates of the scattered points will not cause large changes in the Thiessen polygon structure;

[0028] 3) The obtained structure does not contain disconnected nodes or disconnected segments;

[0029] 4) Without a node connection as an intermediary, these support structures will never cross or overlap;

[0030] 5) All variables describing the structure are scalar values ​​and are only subject to fixed upper and lower bounds; the structural design can be easily expanded by increasing the value of the design variable for each scatter point or increasing the number of scatter points.

[0031] The present invention also discloses a design method for a fiber-reinforced composite 3D printer wing based on Voronoi. In response to the problem that traditional beam-rib wing structures are difficult to form and process in an integrated manner, a method for using a support structure represented by Voronoi as internal filling for the wing is established. The method constructs the Voronoi structure through a set of initial points in the area and performs centroid processing on it to improve the polygonal structural morphology, thereby forming a uniform and stable internal structure. The structure is then filled into the interior of the wing through a geometric mapping method, and the fiber printing path is rationally planned to complete the processing and manufacturing of the fiber-reinforced wing. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the technical roadmap for the fiber-reinforced, integrated, lightweight wing structure of the embodiment of the present application;

[0033] Figure 2 This is a structural diagram of a fiber-reinforced, integrated lightweight wing according to an embodiment of the present application;

[0034] Figure 3 This is a diagram of the voronoi iterative process based on Llyod in an embodiment of the present application;

[0035] Figure 4 This is a schematic diagram of the printing path of the fiber-reinforced, integrated, lightweight wing structure of an embodiment of the present application.

[0036] 1-Outer contour; 2-Frame structure; 3-Thiessen polygon; 4-Diagonal bracing part. DETAILED DESCRIPTION

[0037] The present invention is described in further detail below with reference to the accompanying drawings:

[0038] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention; the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance; in addition, unless otherwise expressly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be a communication between the internal parts of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] like Figure 1 As shown, the present invention discloses a fiber-reinforced 3D printed lightweight wing structure based on Voronoi. The wing includes an outer contour 1, and a frame structure 2 is arranged inside the outer contour 1. The frame structure 2 is composed of a filling structure of Thiessen polygons 3 based on Llyod convergence. The structure fills the entire interior of the wing and is basically evenly distributed along the chord length. The outer contour 1 is wrapped with a skin, and the upper and lower inner surfaces of the skin are respectively connected to the frame structure 2. In this way, while ensuring quality, the force exerted on the skin can be transmitted to the frame structure, which can play a better bearing role. At the same time, the wing structure also has corresponding diagonal bracing parts 4 to play a role in load transmission. See Figure 2 The diagonal brace 4 is a Tyson multi-shaped deformation 3 and is shared by adjacent Tyson multi-shaped deformations 3. The frame structure 2 has the same structural form at any cross-section along the wing's span. Because this structure has no gaps along the span and runs through the entire wing, it can achieve fiber-reinforced integrated molding and manufacturing, further improving the wing structure's corresponding load-bearing characteristics while ensuring quality.

[0040] This structure evolved from the Thiessen polygon structure. Using the Lloyd algorithm, the corresponding sites of the Thiessen polygon units are moved to their centroids, thus centroiding them. This changes the shape of the generated polygon units, resulting in a more uniform and stable support structure than the original. The structure maintains the same form at any cross-section along the wing's span.

[0041] See also Figure 1 A method for designing and manufacturing a fiber-reinforced 3D-printed lightweight wing structure based on Voronoi, comprising the following steps:

[0042] A. Use modeling software to draw or use the airfoil design tool Profili to export the required airfoil such as Figure 2 The airfoil shown, that is, the outer contour 1 of the wing is obtained.

[0043] B. Based on the outer contour 1, use the measurement command in the 3D modeling software to measure the distance between the leading edge point and the trailing edge point of the wing, that is, the chord length a.

[0044] C. Create a closed surface enclosed by the outer contour 1, and use the surface measurement command to obtain the surface area S enclosed by the airfoil contour line. Divide this area S by the chord length a of the wing to obtain the average width b corresponding to the airfoil.

[0045] D. The chord length a of the airfoil and the corresponding average width b calculated above are respectively set as the rectangular boundary lengths x and y corresponding to the generated Thiessen polygon area.

[0046] E.See Figure 3 , randomly generate n sites in a given rectangular area and connect adjacent sites in pairs in turn. Then retain the corresponding Delaunay triangle according to the judgment criteria of Delaunay triangle. On this basis, generate the corresponding Thiessen polygon graph, integrate each cell of the Thiessen polygon graph and calculate the centroid. Through the Lylod algorithm, move each site n to the corresponding centroid position of its Thiessen polygon unit, thus forming a uniform and stable Thiessen polygon graph. The approximation process is divided into multiple steps, as shown in the following process. Figure 3 As shown, the '+' sign represents the seed point, and the 'o' sign represents the centroid of the Thiessen polygon unit cell. Preferably, the approximation operation is performed simultaneously on the sites and centroids of multiple Thiessen polygons.

[0047] F. Use programming software to extract the coordinate information of the n sites in the Thiessen polygon graph based on Llyod convergence, and record them as (x0, y0), (x1, y1), (x2, y2) ... (x n ,y n ), the origin of the coordinate system is the lower left corner of the rectangular area.

[0048] G. Use the proportional mapping method to map the coordinates of the points extracted above to the interior of the airfoil to obtain a series of new coordinate points (x0', y0'), (x1', y1'), (x2', y2')... (x n ',y n'). The specific operation is as follows: Taking the coordinates (x0, y0) as an example, for the point (x0, y0), since the length of the rectangular boundary corresponding to the generated Thiessen polygon area is the chord length of the airfoil, the horizontal coordinate of this point remains unchanged after mapping, that is, x0'=x0, which is the distance between this point and the end point of the leading edge of the airfoil. For the vertical coordinate of this point, first find the width value b1 of the wing corresponding to the point x0'. Then, by calculating the thickness of the wing corresponding to the horizontal coordinate of this point multiplied by the ratio of the vertical coordinate of this point in the original Thiessen polygon rectangular area to the width of its boundary, the mapped value is obtained, that is, y0'=b1*y0 / y, which is the distance between this point and the lower end point of the wing thickness corresponding to the part x0'. y0 is the vertical coordinate of the point in the original rectangular area, y is the width of the original rectangular area, b1 is the wing thickness value at the position corresponding to the mapped point x0', and y0' is the vertical distance between the mapped point and the lower chord line of the airfoil. Similarly, the mapped points (x1', y1'), (x2', y2')...(x n ',y n The coordinate values ​​of ') are the same as those described above, and so on, all the corresponding sites in the original Thiessen polygon rectangular generation area are traversed and mapped to the corresponding airfoil surface in turn to obtain the coordinate values ​​of the mapped n sites.

[0049] H. Connect the discrete sites in the above airfoil section in pairs, then make the perpendicular bisector of each connecting line and intersect it with the outer contour of the wing to obtain the corresponding frame structure. It should be noted that considering the continuity of the structure and the process characteristics, the discontinuous part of the support structure near the trailing edge is removed, and the part near the trailing edge of the wing is not connected to the front triangular frame, so the unconnected lines are removed. The remaining structure is the final support filling structure. Figure 2 shown.

[0050] I. By changing the corresponding number of sites n and the number of optimization steps in step 5), polygonal structures with different structural forms can be obtained. By repeating the subsequent steps, wing structures with different filling forms can be obtained.

[0051] A method for manufacturing a fiber-reinforced 3D-printed lightweight wing structure based on Voronoi, comprising the following corresponding steps:

[0052] A. Use 3D modeling software to measure or use programming software to find out the coordinate information of the intersection between the support structure and the wing. Sort the obtained intersection coordinate information reasonably to obtain a closed-loop continuous path with the coordinate points connected end to end. Specifically, the wing structure obtained by the above design uses the projection command in the 3D modeling software catia to extract the configuration of the wing outer contour and segment the wing outer contour according to several points. Then, the measurement command is used to obtain the coordinate information of the points that make up the wing outer contour and the intersection coordinate information of the skin and the wing support structure (or the corresponding intersection coordinate information is obtained through programming software). According to the obtained coordinate point information, the end-to-end traversal sorting and reasonable path planning are performed along the chord length direction to obtain the continuous path corresponding to the printing, such as Figure 4 As shown, the outer contour of the wing is printed from point 1. The direction of the printing path is indicated by the large arrow in the figure. After the fiber is formed, the internal support structure is printed from point 1 (2). The printing path of the internal support structure is shown by the small arrow in the figure. The corresponding printing path points are 3-92. After the printing of the support structure is completed, it returns to the printing starting point 1 to form the printing path of the wing structure. (First print the outer contour of the wing, then print the internal frame structure)

[0053] B. Combine the coordinate point information obtained above and the corresponding printing path and the process characteristics of continuous fiber 3D printing to reasonably set the relevant printing process parameters during the printing process. Specifically, according to the coordinate point information obtained in step A and the printing path of the fiber wing combined with the configuration of the wing, the scanning spacing, printing temperature, printing speed and other relevant process parameters in the printing process are reasonably set. The resin feed amount E is obtained by calculation based on the process characteristics of continuous fiber printing. First, the resin feed amount of the printing starting point is determined to be 0. The feed amount of each point in the subsequent path is related to the distance from the previous point and the resin feed amount. That is, 0.124 times the distance between a point in the printing path and the point before it plus the resin feed amount of the previous point. The resin feed amount E corresponding to the continuous fiber printing can be obtained by the above calculation method.

[0054] C. Using programming software, convert the obtained printing process parameters and corresponding coordinate point information into a data file format readable by the corresponding continuous fiber printing device. Specifically, the coordinates and sequence of the data points obtained in step A and the resin feed rate calculated in step 2 are combined with the G-code format characteristics that the printing device can recognize, and the programming software is used to convert them into a G-code information format that the continuous fiber printing device can recognize.

[0055] D. Import the relevant data from the above file into the continuous fiber printing device and preview the corresponding printing path. Then, using continuous fiber as the reinforcement (preferably with a fiber content of 20-30%) and a thermoplastic material as the matrix, heat and melt the corresponding printing raw materials to prepare the corresponding printing materials. The fiber-reinforced lightweight wing structure is produced according to the corresponding printing path. The continuous fiber can be carbon fiber, aramid fiber, polyethylene fiber, or glass fiber. Examples of thermoplastic materials include nylon PLA. Preferably, the printing material is continuous carbon fiber-reinforced nylon.

[0056] Specifically, the G code obtained in step C is imported into the printing system corresponding to the continuous fiber printing device and the relative printing origin is set. Then, by displaying the single-layer command and editing the G code, it is previewed whether the specific printing path of the print head during the printing process is the same as the printing path set in step 1. If there is a problem, the code coordinates are modified. If there is no problem, printing is performed with carbon fiber as the reinforcement and nylon material as the matrix to obtain a fiber lightweight wing structure that can be integrated.

[0057] The above steps are obtained through a continuous fiber printing process, and can also be obtained through other fiber printing processes.

[0058] The programming software in the above steps is mtalab, C, C++, Python, etc. The 3D modeling software in the steps is solidworks, CATIA, proe, ug, etc.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A fiber-reinforced composite 3D printed wing based on Voronoi, characterized in that: The invention comprises an outer contour (1), a frame structure (2) is provided inside the outer contour (1), the frame structure (2) is composed of a plurality of Thiessen polygons (3), the outer portion of the outer contour (1) is wrapped by a skin, and the frame structure (2) is connected to the inner surface of the skin; The frame structure (2) has the same structural form at any cross section along the wing span direction; Each Thiessen polygon (3) is provided with an oblique support portion (4), and upper and lower adjacent Thiessen polygons (3) share the oblique support portion (4); The coordinate information of the intersection of the support structure and the wing is measured using 3D modeling software or calculated using programming software. The obtained intersection coordinate information is reasonably sorted to obtain a closed-loop continuous path with the coordinate points connected end to end. Specifically, the upper wing structure is used to extract the configuration of the wing outer contour in the 3D modeling software CATIA using the projection command and the outer contour of the wing is segmented according to a number of points. Then, the measurement command is used to obtain the coordinate information of the points constituting the wing outer contour and the coordinate information of the intersection of the skin and the wing support structure. According to the obtained coordinate point information, the end-to-end traversal sorting and reasonable path planning are performed along the chord length direction to obtain the continuous path corresponding to the printing, that is, the outer contour of the wing is printed first, and the internal support structure is printed after the fiber is formed. After the printing of the support structure is completed, the printing starting point is returned to the printing starting point to form a printing path for the wing structure.

2. A Voronoi-based fiber-reinforced composite material 3D printer wing according to claim 1, characterized in that: The outer contour (1) and the frame structure (2) are made of the same material, the matrix of the material is a thermoplastic material, and the reinforcement is continuous fiber.

3. The fiber-reinforced composite 3D printer wing based on Voronoi according to claim 1, characterized in that: The frame structure (2) is prepared by 3D printing, and the printing path during the printing process is a continuous path.

4. The fiber-reinforced composite 3D printer wing based on Voronoi according to claim 3, characterized in that: In the continuous path, the outer contour of the wing is printed first (1), and then the wing frame structure (2); The 3D printing is a fiber printing process.

5. A method for designing a fiber-reinforced composite 3D printer wing based on Voronoi according to claim 1, characterized in that: The following steps are involved: Step 1, draw the outer contour of the wing (1) and determine the chord length of the wing; Step 2, establish a closed surface enclosed by the outer contour (1), and determine the average width of the wing through the surface area and chord length of the closed surface; Step 3, generate a rectangle by chord length and average width; Step 4: randomly generate n sites in the rectangular area, generate Thiessen polygons around each site, and move the site to the centroid of the Thiessen polygon where the site is located using the Lloyd algorithm to generate uniform and stable Thiessen polygons; Step 5, extract the coordinates of n sites in multiple stable Thiessen polygons, map the coordinates of the n sites to the outer contour (1) of the wing, obtain the coordinate values ​​of the new n sites in the outer contour (1) of the wing, and generate multiple mapped Thiessen polygons (3) in the outer contour (1) of the wing through the coordinate values ​​of the n sites. All the mapped Thiessen polygons (3) form a frame structure (2), completing the design of the 3D printed wing.

6. The method for designing a fiber-reinforced composite material 3D printer wing based on Voronoi according to claim 5, characterized in that: In step 2, the average width is obtained by dividing the curved surface area of ​​the wing by the chord length of the wing.

7. The method for designing a fiber-reinforced composite material 3D printer wing based on Voronoi according to claim 5, characterized in that: In step 4, after connecting adjacent sites in pairs, multiple Delaunay triangles are obtained according to the standard of Delaunay triangles, and multiple Thiessen polygons are generated through the Delaunay triangles.

8. The method for designing a fiber-reinforced composite material 3D printer wing based on Voronoi according to claim 5, characterized in that: In step 5, the coordinate information of all Thiessen polygons is extracted and mapped to the coordinate system of the outer contour of the wing (1). For any coordinate point (x i ,y i ), the coordinate point after mapping is (x i ， ,y i ， ), x i ， = x i ,y i ， =b1*y i / y, b1 is x ’ The wing width corresponding to the horizontal coordinate.

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