Flutter-type prototype and method for manufacturing the flutter-type prototype
The lattice-structured flutter wind test model, fabricated using a 3D printer, addresses high manufacturing costs by enabling adjustable mass and stiffness distribution, thus improving the accuracy and efficiency of wind tunnel testing.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- SUBARU CORP
- Filing Date
- 2022-05-16
- Publication Date
- 2026-05-20
AI Technical Summary
The manufacturing cost of flutter-type prototypes is high due to the complexity and material requirements of simulating aircraft parts for wind tunnel testing.
A flutter wind test model is designed with a lattice structure for internal parts, fabricated using a 3D printer, allowing for adjustable mass and stiffness distribution by varying density and material composition, and assembled with solid structures to simulate aircraft components.
This approach reduces manufacturing time and cost while accurately simulating the deformation and vibration characteristics of aircraft parts, enhancing the fidelity of wind tunnel testing.
Smart Images
Figure 0007862982000001 
Figure 0007862982000002 
Figure 0007862982000003
Abstract
Description
Technical Field
[0001] Embodiments of the present invention relate to a flutter wind test model and a method for manufacturing the flutter wind test model.
Background Art
[0002] During flight, periodic self-excited vibrations occur in the wings and fuselage of an aircraft due to the flow of air. The phenomenon of vibration occurring in an aircraft during flight due to air currents is called flutter, and a wind tunnel test using a model is conducted to confirm the state of flutter occurring in each part such as the main wing of the aircraft.
[0003] It is essential that the flutter wind test model used in the flutter wind tunnel test be designed to deform due to flutter occurring in the wind tunnel, similar to aircraft parts such as the main wing to be simulated. Therefore, the flutter wind test model is designed based on the rigidity and mass distribution of the aircraft part so that the vibration characteristics such as the natural frequency and vibration mode are equal to those of the aircraft part to be simulated. And, a conventional flutter wind test model is manufactured by forming an airfoil with a flexible resin on a metal plate using a mold.
[0004] In addition, as wind tunnel tests using models simulating aircraft parts, there are also known wind tunnel tests for measuring the pressure distribution on the surface of the main wing etc. and icing wind tunnel tests for examining the behavior of icing on the main wing etc. (see, for example, Patent Document 1 and Patent Document 2).
Prior Art Documents
Patent Documents
[0005]
Patent Document 1
Patent Document 2
Summary of the Invention
Problems to be Solved by the Invention
[0006] The present invention aims to reduce the manufacturing cost of flutter-type prototypes. [Means for solving the problem]
[0007] The flutter wind test model according to the embodiment of the present invention simulates the shape and vibration characteristics of an aircraft component in order to perform flutter wind tunnel testing of the aircraft component. At least a part of this flutter wind test model is A lattice is a structure in which branched, grid-like structures are arranged periodically. It is composed of structures.
[0008] Furthermore, the method for manufacturing a flutter wind test model according to the embodiment of the present invention is a method for manufacturing a model that simulates the shape and vibration characteristics of an aircraft part in order to perform flutter wind tunnel testing of the aircraft part. In this method, A lattice is a structure in which branched, grid-like structures are arranged periodically. The structure is fabricated using a 3D printer, and the above Lattice The structure constitutes at least a part of the aforementioned flutter wind prototype. [Brief explanation of the drawing]
[0009] [Figure 1] An exploded perspective view illustrating an example of the structure of a flutter wind prototype according to an embodiment of the present invention. [Figure 2] A partially enlarged perspective view of the flutter wind prototype shown in Figure 1, near section B. [Figure 3] A schematic perspective view showing an aircraft wing as an example of an aircraft component simulated by the flutter wind prototype shown in Figure 1. [Figure 4] Figure 1 illustrates an example of a manufacturing method for the flutter wind prototype shown in Figure 1. [Figure 5] A flowchart showing an example of how to create 3D shape data to be output to a 3D printer, as shown in Figure 4. [Figure 6] A diagram showing an example of a flutter-wind model with partially varied density of non-solid structures. [Figure 7] This diagram shows an example of a flutter-type prototype with a cylindrical weight placed inside. [Figure 8] Figure 7 shows an enlarged longitudinal cross-sectional view of the weight. [Figure 9]A diagram showing an example of a flutter wind test model in which a plate is arranged inside a non-solid structure. [Figure 10] An enlarged cross-sectional view at position C-C of the flutter wind test model shown in Fig. 9. [Figure 11] A diagram showing an example of a flutter wind test model in which a rod is arranged inside a non-solid structure. [Figure 12] An enlarged cross-sectional view at position D-D of the flutter wind test model shown in Fig. 11.
Embodiments for Carrying out the Invention
[0010] The flutter wind test model according to an embodiment of the present invention and a method for manufacturing the flutter wind test model will be described with reference to the accompanying drawings.
[0011] (Configuration and Function of Flutter Wind Test Model) Fig. 1 is an exploded perspective view for explaining a structural example of a flutter wind test model 1 according to an embodiment of the present invention, Fig. 2 is a partial enlarged perspective view near part B of the flutter wind test model 1 shown in Fig. 1, and Fig. 3 is a schematic perspective view showing a main wing MW of an aircraft A as an example of an aircraft part P simulated by the flutter wind test model 1 shown in Fig. 1.
[0012] The flutter wind test model 1 shown in Fig. 1 is a model for performing a flutter wind tunnel test on an aircraft part P. That is, the flutter wind test model 1 is arranged and used in a wind tunnel for flutter tests, and the deformation of the flutter wind test model 1 when flutter occurs in the flutter wind test model 1 due to the air flow in the wind tunnel is observed.
[0013] Therefore, the flutter wind test model 1 simulates not only the shape of the aircraft part P but also the vibration characteristics of the aircraft part P. Fig. 1 shows an example in which the flutter wind test model 1 simulates the main wing MW of an aircraft A as shown in Fig. 3. Of course, not limited to the main wing MW, aircraft parts P such as a tail wing and a fuselage may also be simulated by the flutter wind test model 1.
[0014] The flutter wind test model 1 shown in Fig. 1 shows the state before attaching the plate-like member 2 that simulates the outer plate of the main wing MW. The plate-like member 2 has a solid structure 3 so that aerodynamic forces are applied in the wind tunnel in the same manner as the main wing MW. That is, the surface of the plate-like member 2 is a curved surface without holes, similar to the outer plate of the main wing MW. Therefore, the plate-like member 2 is deformed by receiving aerodynamic forces in the wind tunnel.
[0015] On the other hand, the internal part 4 covered by the plate-like member 2 has a non-solid structure 5. More specifically, the internal part 4 of the flutter wind test model 1 has a non-solid structure 5 with uniformly branched gaps inside. Typical examples of the non-solid structure 5 with uniformly branched gaps inside include a lattice structure and a porous structure. The lattice structure is a structure in which branched lattice-like elements are arranged periodically. On the other hand, the porous structure is a sponge-like structure with a large number of pores inside.
[0016] As the non-solid structure 5, a combination of a plurality of structures may be used. Therefore, the non-solid structure 5 may be at least one of a lattice structure and a porous structure, or may be further combined with other structures. Fig. 1 shows an example in which the non-solid structure 5 is composed only of a lattice structure, as shown in the enlarged view of Fig. 3.
[0017] In the uniform non-solid structure 5 typified by the lattice structure and the porous structure, the volume of the portion other than the gaps per unit volume is determined by the density. Therefore, by appropriately determining the density distribution in the internal part 4 having the non-solid structure 5, it is possible to freely adjust at least one of the mass distribution and the rigidity distribution of the flutter wind test model 1.
[0018] For example, if the non-solid structure 5 is a lattice structure, the density distribution in the interior part 4 having the non-solid structure 5 can be adjusted by changing parameters such as the density of the grid and the thickness of the rod-shaped members constituting the grid at each location. Similarly, even if the non-solid structure 5 is a porous structure, the density distribution in the interior part 4 having the non-solid structure 5 can be adjusted by changing parameters such as the size and density of the voids.
[0019] Furthermore, in addition to adjusting the density of the internal part 4 having the non-solid structure 5, at least one of the mass distribution and stiffness distribution of the flutter wind model 1 can also be adjusted by appropriately selecting the material for the internal part 4 having the non-solid structure 5. At least one of metal and resin can be used as the material for the part 4 having the non-solid structure 5. Of course, the part 4 having the non-solid structure 5 may be constructed using multiple different materials at different locations.
[0020] Furthermore, while the main material of aircraft parts P is almost always metal or fiber-reinforced plastics (FRP), which have a higher specific gravity than resin, a typical main wing MW is a hollow fuel tank reinforced with reinforcing members such as ribs, spars, and stringers, and other parts such as the fuselage are also hollow structures. Therefore, if the density of the non-solid structure 5 is sufficiently large, the mass distribution and stiffness distribution of aircraft parts P can be simulated by the non-solid structure 5 even if the non-solid structure 5 is made only of resin.
[0021] Similarly, the plate-shaped member 2 having a solid structure 3 can also be made of at least one of metal and resin. Therefore, if the material of the plate-shaped member 2 and the material of the internal part 4 are the same, the manufacturing cost of the flutter wind prototype 1 can be reduced. Conversely, in order to optimize the mass distribution and stiffness distribution of the flutter wind prototype 1, the plate-shaped member 2 and the internal part 4 may be made of different materials.
[0022] Furthermore, in order to adjust the mass distribution and stiffness distribution of the flutter wind prototype model 1, as shown in Figure 1, instead of making the entire internal part 4 a non-solid structure 5, a portion may be made a non-solid structure 5 and the remaining part a solid structure. In that case, the plate-shaped member 2 and the part having the internal solid structure may be made as one unit.
[0023] In other words, while at least a portion of the flutter wind test model 1 is made of a non-solid structure 5, the portion of the flutter wind test model 1 that simulates at least the parts of the aircraft component P that form surfaces subjected to aerodynamic forces, such as the upper surface, leading edge, trailing edge, and lower surface of the main wing MW, can be made of a solid structure 3 without gaps so that aerodynamic forces are applied during the flutter wind tunnel test.
[0024] Even in that case, both the solid structure 3 and the non-solid structure 5 may be made of resin or metal, or the non-solid structure 5 made of metal or resin may be placed inside the solid structure 3 made of resin or metal. Alternatively, part of the solid structure 3 may be made of resin and the remaining part of metal, or part of the non-solid structure 5 may be made of resin and the remaining part of metal.
[0025] When constructing the flutter-style prototype 1 by assembling multiple parts, whether the solid structure 3 and the non-solid structure 5 are made of different materials or the same material, the parts can be connected using any connection method, such as adhesive, fitting, or screwing.
[0026] (Method of manufacturing a flutter-type prototype) Next, we will describe the manufacturing method of the flutter wind prototype 1 and a more detailed structural example of the manufactured flutter wind prototype 1.
[0027] Figure 4 illustrates an example of a manufacturing method for the flutter wind prototype 1 shown in Figure 1.
[0028] As shown in Figure 4, the internal part 4 of the flutter wind prototype 1, which has a non-solid structure 5 such as a lattice structure or a porous structure, can be fabricated using a three-dimensional (3D) printer (additive manufacturing device) 10. Furthermore, the 3D shape data to be output to the 3D printer 10 can be created using a computer 11.
[0029] If aircraft A is a supersonic aircraft, the size of the flutter-wind prototype 1, which simulates typical aircraft parts P such as the main wing MW, will be approximately 30 cm to 60 cm, and if aircraft A is a subsonic aircraft, it will be approximately 1 m to 2 m. Therefore, using a 3D printer 10 capable of fabricating a flutter-wind prototype 1 of the desired size, the internal part 4 having at least a non-solid structure 5 can be manufactured.
[0030] Since the 3D printer 10 can also fabricate solid structures, if the internal part 4 having a non-solid structure 5 and the plate-shaped member 2 having a solid structure 3 are made of the same material, both the non-solid structure 5 and the solid structure 3 can be fabricated integrally with the 3D printer 10. This is also true when a part of the internal part 4 is made of a solid structure.
[0031] In addition to devices that use resin as a material, 3D printers 10 that use metal as a material are also commercially available. Specifically, by using 3D printers 10 that employ methods such as Fused Deposition Modeling (FDM), stereolithography, or inkjet, it is possible to create three-dimensional objects with complex shapes using thermoplastic resins such as ABS resin, PLA resin, polypropylene resin, acrylic resin, or polyethylene terephthalate (PET), thermosetting resins such as epoxy resins or acrylate resins, or metals such as iron-based metals or aluminum as materials.
[0032] If the flutter-style prototype 1 is too large to be printed in one go by the 3D printer 10, it can be printed in sections. That is, the flutter-style prototype 1 can be printed in sections using a common or multiple 3D printers 10. Also, when the non-solid structure 5 of the flutter-style prototype 1 is printed using a combination of different materials, it can be printed in sections using multiple 3D printers 10. That is, the non-solid structure 5 can be printed in sections using multiple 3D printers 10, one for each material.
[0033] When the non-solid structure 5 is fabricated in sections, or when at least a part of the solid structure 3 is not fabricated by the 3D printer 10, a flutter-style prototype model 1 can be manufactured by assembling fabricated parts having multiple non-solid structures 5, or by assembling fabricated parts having one or more non-solid structures 5 with non-fabricated parts having solid structures 3. Any method of connection between fabricated parts, between fabricated parts and non-fabricated parts, and between non-fabricated parts can be used, such as adhesive, fitting, or screw fastening.
[0034] As a typical example, when fabricating a flutter-wind prototype 1 having a structure in which a non-solid structure 5 is covered with a plate-shaped member 2, as illustrated in Figure 1, the flutter-wind prototype 1 can be fabricated by creating a resin non-solid structure 5 with a 3D printer 10 and bonding it with a metal plate-shaped member 2 having a solid structure 3 using an adhesive, as illustrated in Figure 4.
[0035] Figure 5 is a flowchart showing an example of a method for creating 3D shape data to be output to the 3D printer 10 shown in Figure 4.
[0036] The 3D shape data output to the 3D printer 10, that is, information for identifying the contour of the internal part 4 having at least a non-solid structure 5, can be created by the computer 11 as described above. Note that simple calculations and judgments other than complex calculations such as vibration analysis may be performed by the operator using the computer 11, or without using the computer 11.
[0037] First, in step S1, the vibration characteristics of aircraft components P, such as the main wing MW, which are simulated in the actual aircraft, i.e., the flutter-wind prototype model 1, are determined as target values. The vibration characteristics of the actual aircraft can be calculated by vibration analysis simulation using dedicated vibration analysis software. Alternatively, actual vibration tests using the actual aircraft may also be used.
[0038] Meanwhile, in step S2, a finite element method (FEM) analysis model is created for the flutter wind test model 1, with the non-solid structure 5 set as the initial state.
[0039] Next, in step S3, a vibration analysis is performed using FEM on the FEM analysis model of flutter wind prototype 1. This determines the vibration characteristics of the FEM analysis model.
[0040] Next, in step S4, the vibration characteristics of the actual machine and the vibration characteristics of the FEM analysis model are compared. Specifically, it is determined whether the natural frequencies and vibration mode shapes of the FEM analysis model can be considered to match the natural frequencies and vibration modes of the actual machine. In other words, it is determined whether the difference or ratio between the natural frequencies and vibration mode shapes of the FEM analysis model and the natural frequencies and vibration modes of the actual machine is within an acceptable range.
[0041] If it is determined that the vibration characteristics of the FEM analysis model do not match the vibration characteristics of the actual machine sufficiently, then in step S5, at least one of the mass distribution and stiffness distribution of the non-solid structure 5 defined in the FEM analysis model is changed.
[0042] The mass distribution of the non-solid structure 5 can be changed by modifying the parameters of the FEM analysis model that represent the type and density of the structural pattern of the non-solid structure 5, as well as by placing weights at various positions. On the other hand, the stiffness distribution of the non-solid structure 5 can be changed by modifying the parameters of the FEM analysis model that represent the material of the non-solid structure 5, as well as by placing members with higher stiffness than the material of the non-solid structure 5 at various positions.
[0043] Figure 6 shows an example of a flutter wind model 1 in which the density of the non-solid structure 5 is partially changed.
[0044] Figure 6 shows the flutter-wind test model 1, which simulates the main wing MW of aircraft A, with the plate-like member 2, which simulates the outer skin of the main wing MW, removed. In other words, Figure 6 shows the non-solid structure 5 of the flutter-wind test model 1 exposed. In Figure 6, the density of the mesh represents the density of the non-solid structure 5.
[0045] As illustrated in Figure 6, the density of the non-solid structure 5, which simulates the interior of the main wing MW, can be gradually reduced as it moves away from the fuselage, in accordance with the actual mass distribution of the main wing MW. In the example shown in Figure 6, the non-solid structure 5 is composed of three parts 5A, 5B, and 5C with different densities, more specifically, part 5A with the highest density, part 5B with medium density, and part 5C with the lowest density. Of course, the non-solid structure 5 may also be divided into four or more parts with different densities.
[0046] By partially changing the density of the non-solid structure 5 in this way, the density of the non-solid structure 5 is made non-uniform. This allows for different mass distributions and stiffness distributions to be imparted to the flutter-wind prototype 1 at different locations, even when fabricating the non-solid structure 5 using the same material. Specifically, in the part 5A with relatively high density, the stiffness and mass are also relatively high, while in the part 5C with relatively low density, the stiffness and mass are also relatively low.
[0047] Furthermore, different materials may be used in each part 5A, 5B, and 5C of the non-solid structure 5, which have different densities. In other words, the material used in each part 5A, 5B, and 5C of the non-solid structure 5, which have different densities, may be changed as a parameter.
[0048] Figure 7 shows an example of a flutter-wind prototype 1 with a cylindrical weight 20 placed inside, and Figure 8 is an enlarged longitudinal cross-sectional view of the weight 20 shown in Figure 7.
[0049] Figure 7 shows the flutter-wind test model 1, which simulates the main wing MW of aircraft A, with the plate-like member 2, which simulates the outer skin of the main wing MW, removed. In other words, Figure 7 shows the non-solid structure 5 of the flutter-wind test model 1 exposed. In Figure 7, the density of the mesh represents the density of the non-solid structure 5.
[0050] As illustrated in Figure 7, weights 20 may be placed inside the flutter-wind prototype 1 to adjust the mass distribution. By placing weights 20, it is possible to locally increase the mass of the flutter-wind prototype 1 to match the mass distribution of the actual main wing MW. The shape, size, and material of weights 20 are arbitrary as long as the required mass is obtained.
[0051] In the examples shown in Figures 7 and 8, cylindrical weights 20 are placed in three locations. Therefore, a through-hole without a hole on the inner surface is provided in a part of the non-solid structure 5 so that the cylindrical weights 20 can be fixed inside the flutter-like prototype 1 by press-fitting or bonding with adhesive. The through-hole for positioning the weights 20 can also be formed by 3D printing. Alternatively, a cylindrical socket for inserting the weights 20 can be attached to the outside of the non-solid structure 5 with adhesive, or the weights 20 can be directly bonded to the end of the non-solid structure 5 with adhesive.
[0052] Figure 9 shows an example of a flutter wind test model 1 in which plate 21 is placed inside a non-solid structure 5, and Figure 10 is an enlarged cross-sectional view of the flutter wind test model 1 at position CC shown in Figure 9.
[0053] Figures 9 and 10 show the state after removing the plate-like members 2 that simulate the outer skin of the main wing MW of aircraft A from the flutter wind test model 1, which simulates the main wing MW. In other words, Figures 9 and 10 show the state in which the non-solid structure 5 of the flutter wind test model 1 is exposed. Also, in Figures 9 and 10, the mesh represents the non-solid structure 5 with a constant density.
[0054] As illustrated in Figures 9 and 10, a plate 21 having a solid structure can also be inserted inside the non-solid structure 5. In this case, the mass distribution of the flutter wind model 1 including the non-solid structure 5 can be adjusted by changing the thickness and size of the plate 21. That is, the area having the non-solid structure 5 becomes smaller by an amount corresponding to the area occupied by the plate 21, so the mass can be increased compared to the case where the plate 21 is not inserted.
[0055] In the example shown in Figure 9, the end of the plate 21 inserted into the non-solid structure 5 protrudes from the non-solid structure 5, and the end of the plate 21 protruding from the non-solid structure 5 also serves as a connecting member for the flutter-wind prototype 1.
[0056] Of course, the material of plate 21 can also be changed. For example, if the non-solid structure 5 is manufactured by molding resin, changing the material of plate 21 to metal can increase its mass and rigidity. Alternatively, changing the material of plate 21 to FRP such as carbon fiber reinforced plastics (CFRP) or glass fiber reinforced plastics (GFRP) can improve rigidity without significantly changing the mass. In other words, by changing the material of plate 21, it is possible to make plate 21 function as a weight or as a component to improve rigidity.
[0057] Figure 11 shows an example of a flutter wind test model 1 in which the rod 22 is placed inside the non-solid structure 5, and Figure 12 is an enlarged cross-sectional view of the flutter wind test model 1 at position DD shown in Figure 11.
[0058] Figures 11 and 12 show the state after removing the plate-like members 2 that simulate the outer skin of the main wing MW of aircraft A from the flutter wind test model 1, which simulates the main wing MW. In other words, Figures 11 and 12 show the state in which the non-solid structure 5 of the flutter wind test model 1 is exposed. Also, in Figures 11 and 12, the mesh represents the non-solid structure 5 with a constant density.
[0059] As illustrated in Figures 11 and 12, a rod 22 can be inserted into the non-solid structure 5 instead of, or in addition to, the plate 21. The length, shape, thickness, and material of the rod 22 can also be freely changed. In particular, in the case of the rod 22, by changing the cross-sectional shape to various shapes such as I-beams and H-beams, not limited to circular or polygonal shapes, it is possible to adjust only the rigidity without changing the mass.
[0060] Of course, the rigidity of plates 21, such as those exemplified in Figures 9 and 10, can be improved without substantially changing their mass by applying bead processing or forming them into a corrugated shape.
[0061] Thus, in addition to making overall or partial changes to the density of the non-solid structure 5 defined in the FEM analysis model, at least one of the mass distribution and stiffness distribution of the modeled flutter wind test model 1 can be adjusted by creating an FEM analysis model of the flutter wind test model 1 with at least one of the weights 20, plates 21, and rods 22 placed as needed. When at least one of the mass distribution and stiffness distribution of the flutter wind test model 1 changes, the vibration characteristics of the flutter wind test model 1 also change in accordance with the mass distribution and stiffness distribution.
[0062] Therefore, in step S3, vibration analysis is performed again on the FEM analysis model of flutter wind test model 1, in which at least one of the mass distribution and stiffness distribution has been changed. This yields the vibration characteristics of the FEM analysis model in which at least one of the mass distribution and stiffness distribution has been changed. Subsequently, in step S4, the vibration characteristics of the FEM analysis model are compared with the vibration characteristics of the target actual machine.
[0063] The modification of the FEM analysis model in step S5 and the vibration analysis of the FEM analysis model in step S3 are repeated until the determination in step S4 is YES, that is, until it is determined that the vibration characteristics of the FEM analysis model have come close enough to be considered to match the vibration characteristics of the actual machine.
[0064] In other words, during the design of the flutter wind model 1, at least one of the mass distribution and stiffness distribution of the flutter wind model 1 can be adjusted so that the vibration characteristics of the flutter wind model 1 approach those of the aircraft component P by making at least one of the following: making an overall or partial change to the density of the non-solid structure 5, arranging the weights 21, and arranging members to increase the internal stiffness of the part having the non-solid structure 5.
[0065] In particular, when the non-solid structure 5 is made of resin, adding solid members such as metal or FRP plates 21 or rods 22 inside the flutter-wind prototype 1 can increase the rigidity of the flutter-wind prototype 1 to a degree that would be difficult to achieve by simply changing the density of the non-solid structure 5.
[0066] As explained with specific examples, there are numerous parameters in the FEM analysis model for changing at least one of the mass distribution and stiffness distribution, and there are also numerous possible values for these parameters. In particular, when partially changing the density of the non-solid structure 5, there are countless candidate numbers of region divisions and regions of shape. Therefore, when the target degree of agreement between the vibration characteristics of the FEM analysis model and the vibration characteristics of the actual machine is high, the loop calculation from step S3 to step S5 often becomes a complex optimization calculation aimed at increasing the degree of agreement as much as possible.
[0067] Therefore, software for performing optimization calculations may be used to automatically calculate the values of parameters that must be determined, such as the division method, density distribution, and material of the non-solid structure 5, as well as the values of parameters that may be added as options, such as the presence and arrangement of weights 20, plates 21, and rods 22. Of course, the designer may specify the values of some parameters, or conversely, the designer may specify the values of all parameters.
[0068] If the determination in step S4 is YES due to parameter changes or optimization calculations by the designer, the loop calculation from step S3 to step S5 is terminated. This determines the ideal FEM analysis model. Of the FEM analysis model, at least the part containing the non-solid structure 5 is the part to be fabricated by the 3D printer 10. Therefore, the information for identifying the contour of at least the part containing the non-solid structure 5 of the FEM analysis model becomes the 3D shape data to be output to the 3D printer 10.
[0069] Components unsuitable for fabrication, such as the weight 20, plate 21, and rod 22, are not manufactured by the 3D printer 10. Therefore, the 3D shape data to be output to the 3D printer 10 contains information for fabricating the non-solid structure 5, which has voids and structures for arranging components such as the weight 20, plate 21, or rod 22. Furthermore, if the non-solid structure 5 is fabricated in sections, the 3D shape data to be output to the 3D printer 10 is also divided.
[0070] Once the 3D shape data to be output to the 3D printer 10 is identified, in step S7, the 3D shape data is output to the 3D printer 10. This allows the 3D printer 10 to fabricate the part having a non-solid structure 5 that corresponds to the shape of the FEM analysis model. Subsequently, as explained with reference to Figure 4, the final flutter-wind prototype model 1 is assembled by the assembly process. If there are components such as weights 20, plates 21, or rods 22, they can be attached during the assembly process.
[0071] Furthermore, while we have explained how to compare the vibration characteristics of the FEM analysis model with those of the actual machine using Figure 5 as a reference, if it can be assumed that the vibration characteristics will be similar if the mass distribution and stiffness distribution are the same, then instead of comparing vibration characteristics, the mass distribution and stiffness distribution may be compared. In other words, the mass distribution and stiffness distribution of the actual machine may be set as target values, and the mass distribution and stiffness distribution of the FEM analysis model may be brought closer to these target values.
[0072] In that case, one may first determine lattice structures or porous structures of a unit volume with typical mass and stiffness for each level of mass and stiffness, and then arrange these unit volume lattice structures or porous structures to obtain the desired mass distribution and stiffness distribution, thereby obtaining an FEM analysis model with the desired mass distribution and stiffness distribution.
[0073] (effect) The flutter wind prototype 1 and the manufacturing method for the flutter wind prototype 1 described above utilize a non-solid structure 5 such as a lattice structure for the internal structure, allowing for density adjustment.
[0074] Therefore, the flutter wind prototype 1 and the method for manufacturing the flutter wind prototype 1 can significantly reduce the manufacturing time and cost compared to manufacturing conventional flutter wind prototypes with a solid structure. In other words, if the density distribution and material of the non-solid structure 5 are appropriately calculated and determined by the computer 11, the flutter wind prototype 1 can be easily and inexpensively manufactured using the 3D printer 10.
[0075] Furthermore, compared to conventional flutter-wind prototypes with a solid structure, it is possible to easily impart a more appropriate mass distribution and stiffness distribution to the flutter-wind prototype 1 so that it undergoes deformation similar to that of an actual machine due to flutter.
[0076] (Other embodiments) Although specific embodiments have been described above, these embodiments are merely examples and do not limit the scope of the invention. The novel methods and apparatus described herein can be embodied in various other forms. Furthermore, various omissions, substitutions, and modifications can be made in the forms of methods and apparatus described herein, without departing from the spirit of the invention. The attached claims and equivalents include such various forms and modifications as being encompassed within the scope and spirit of the invention. [Explanation of Symbols]
[0077] 1. Flutter-style prototype model 2. Plate-shaped member 3. Solid structure 4. Internal parts 5 Non-solid structure 5A, 5B, 5C: Areas with different densities 10 3D printers 11 Computer 20 weights 21 plates 22 rods A aircraft MW main wing P Aircraft parts
Claims
1. In a flutter wind test model that simulates the shape and vibration characteristics of an aircraft component in order to conduct flutter wind tunnel tests on the aircraft component, A flutter-like prototype model that incorporates a lattice structure, which is a structure in which branched grids are arranged periodically, at least partially.
2. The flutter-like prototype according to claim 1, wherein the lattice structure is made of resin.
3. The flutter wind test model according to claim 1 or 2, wherein at least the portion of the aircraft component that simulates the portion that forms the surface subject to aerodynamic forces is constructed with a solid structure without gaps so that aerodynamic forces are applied in the flutter wind tunnel test.
4. The flutter-wind prototype according to Claim 3, wherein the material of the lattice structure and the material of the gapless solid structure are the same material.
5. A method for manufacturing a flutter wind test model that simulates the shape and vibration characteristics of an aircraft part in order to perform a flutter wind tunnel test of the aircraft part, A method for manufacturing a flutter wind prototype, comprising fabricating a lattice structure, which is a structure in which branched grids are arranged periodically, using a 3D printer, and using the lattice structure to form at least a part of the flutter wind prototype.
6. A method for manufacturing a flutter wind model according to claim 5, which involves adjusting at least one of the mass distribution and stiffness distribution of the flutter wind model so that the vibration characteristics of the flutter wind model approach those of the aircraft component, by partially changing the density of the lattice structure, arranging weights, and arranging members to increase the internal stiffness of the portion having the lattice structure.