Method and system for modeling three-dimensional geometric model of airfoil structure

Abstract

The application belongs to the technical field of aviation design, and provides a kind of aviation wing structure three-dimensional geometric model modeling method and system, in the iteration optimization process of wing spar, wing rib and stringer in initial model, first determine the offset, then the original grid vertex in model is expanded along normal direction to generate new vertex set, the offset surface topology structure is reconstructed by triangulation, when reconstructing offset surface topology structure, the number of grid vertex is adjusted according to offset, to improve the quality of model reconstruction, when the average value of offset coordinate is greater than or equal to the average value of original model coordinate, the number of grid vertex is increased, otherwise, the number of grid vertex is reduced, to improve the speed of model reconstruction; on the basis of ensuring modeling efficiency, the problem of reducing model accuracy after geometric reconstruction due to insufficient grid division proportion is solved.

Description

Technical Field

[0001] This invention belongs to the field of aviation design technology, and in particular relates to a method and system for modeling three-dimensional geometric models of aircraft wing structures. Background Technology

[0002] The wing structure design process is divided into two stages: prototyping and detailed design. In the prototyping stage, a two-dimensional layout design of the components is first performed, followed by the creation of a three-dimensional geometric model. Finite element analysis is then conducted on the 3D model to evaluate the main structural performance. Based on the analysis results, the two-dimensional layout is modified until the requirements are met. Due to the iterative and cyclical nature of prototyping, the process from two-dimensional layout design and modification to the creation of the three-dimensional geometric model typically consumes a significant amount of time for structural designers, impacting aircraft design efficiency. With the development of computer-aided design (CAD) technology, parametric modeling methods have gradually been applied in design, improving design efficiency to some extent.

[0003] The geometric parameters of key components in the wing structure, such as ribs, spars, and stringers, need to be adjusted multiple times. Each time the offset surface topology is reconstructed in each iteration, the coordinates of the surface vertices change. Therefore, if the original mesh vertices are used directly as the scatter set, the model accuracy will be reduced after geometric reconstruction due to insufficient mesh division. On the other hand, adding too many meshes will affect modeling efficiency. In addition, the increase in curvature error due to size changes, as well as processes such as opening edges and patching surfaces, will also affect modeling accuracy and efficiency. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a method and system for modeling three-dimensional geometric models of aircraft wing structures. During the iterative optimization of the wing spars, ribs, and stringers in the initial model, the offset is first determined. Then, the original mesh vertices in the model are expanded along the normal direction to generate a new vertex set. The offset surface topology is reconstructed through triangulation. During the reconstruction of the offset surface topology, the number of mesh vertices is adjusted according to the offset to improve the model reconstruction quality. When the average coordinates after offset are greater than or equal to the average coordinates of the original model, the number of mesh vertices is increased; otherwise, the number of mesh vertices is reduced to improve the model reconstruction speed. While ensuring modeling efficiency, this invention solves the problem of reduced model accuracy after geometric reconstruction due to insufficient mesh partitioning.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] In a first aspect, the present invention provides a method for modeling a three-dimensional geometric model of an aircraft wing structure, comprising:

[0007] Obtain the initial model of the aircraft wing;

[0008] Finite element simulation is performed on the initial model of the aircraft wing. If the finite element simulation results meet the preset requirements, the final model is obtained; otherwise, the initial model is optimized.

[0009] The wing spars, ribs, and stringers in the initial model are iteratively optimized until the finite element simulation results meet the preset requirements. In the iterative optimization process of the wing spars, ribs, and stringers in the initial model, the offset is first determined, and then the original mesh vertices in the model are expanded along the normal direction to generate a new vertex set. The offset surface topology is reconstructed by triangulation. When reconstructing the offset surface topology, the number of mesh vertices is adjusted according to the offset. When the average coordinate of the offset is greater than or equal to the average coordinate of the original model, the number of mesh vertices is increased; otherwise, the number of mesh vertices is reduced.

[0010] Furthermore, the number of new vertex sets generated by expanding the original mesh vertices along the normal direction is:

[0011] ;

[0012] in, The number of new vertex sets generated by expanding the original mesh vertices along the normal direction; This represents the original number of mesh vertices; The average coordinates after model offset; This represents the average coordinates of the original model; and These are preset coefficients.

[0013] Furthermore, during the establishment and iterative optimization of the wing spars model, multiple station planes are created sequentially perpendicular to the reference plane based on the wing chord plane and the beam projection lines in the layout diagram. Planes are created on the reference plane, and for the completed planes, they are thickened according to the thickness parameters to obtain the beam rough model. The beam rough model is then divided to obtain the beam entity in the middle of the upper and lower wing surfaces.

[0014] Furthermore, the correctness of the created beam station planar topology is verified. If the closure requirement is not met, stitching is performed. Offset calculations are performed on all topological vertices, and the original mesh vertices are expanded along the normal direction to generate a new vertex set. The offset surface topology is constructed using the Delaunay triangulation algorithm. All edge structures are traversed using the boundary loop detection method, and the edge sharing state is recorded using a hash table. Appendage patches are automatically generated for detected open edges. Fast collision detection is performed based on the spatial partitioning tree, and local mesh reconstruction is performed on the patches that have penetrated each other. The least squares method is used to optimize and adjust the vertex positions, eliminating self-intersections while maintaining curvature continuity. The newly formed surfaces are then stitched together with topological data to create a three-dimensional solid structure.

[0015] Furthermore, when generating the patch, tangents are drawn at both ends of the open edge. If the two tangents coincide or the angle between the tangents is less than the preset angle value, the patch is directly performed; otherwise, auxiliary points are added at the open opening before the patch is performed.

[0016] Furthermore, during rib optimization, a Boolean sum is first performed on a single rib and an intersecting single spar to obtain a single solid. Then, the obtained solids are segmented sequentially using the sides of the spar as a reference to complete rib segmentation. Finally, each rib is individually shelled according to its thickness parameters to generate a hollow structure, thus completing rib creation.

[0017] Furthermore, self-intersection detection and repair are performed, the offset surface is discretized into a triangular mesh, a tree-accelerated collision detection algorithm is used to detect penetration between meshes, and then direction control and coordinate system transformation are performed to ensure that the normal vectors of all retained surfaces point to the same side; solid reconstruction is performed, and solid Boolean subtraction is used to realize the subtraction of the solid.

[0018] Furthermore, during the creation and optimization of the stringer, the stringer lines in the two-dimensional layout drawing are projected onto the upper and lower skin surfaces to generate projection lines. Then, based on the cross-sectional sketch and projection lines, a sweeping process is performed to create a three-dimensional solid stringer.

[0019] Furthermore, during string creation and optimization, the projection point of each discrete point on the surface is calculated, connected to form a curve, and an entity is created based on the interface and path.

[0020] Furthermore, during stringer creation and optimization, interpolation and coordinate transformation are performed, including: using uniform arc length sampling to discretize the path into multiple sampling points, determining the tangent and normal parameters of multiple sampling points, and placing the cross-section in the local coordinate system of the sampling points.

[0021] Secondly, the present invention also provides a three-dimensional geometric modeling system for aircraft wing structures, comprising:

[0022] The initial model acquisition module is configured to acquire the initial model of an aircraft wing;

[0023] The judgment module is configured to: perform finite element simulation on the initial model of the aircraft wing; if the finite element simulation results meet the preset requirements, the final model is obtained; otherwise, the initial model is optimized.

[0024] The optimization module is configured to iteratively optimize the design of the wing spars, wing ribs, and stringers in the initial model until the finite element simulation results meet the preset requirements. In the iterative optimization process of the wing spars, wing ribs, and stringers in the initial model, the offset is first determined, and then the original mesh vertices in the model are expanded along the normal direction to generate a new vertex set. The offset surface topology is reconstructed through triangulation. When reconstructing the offset surface topology, the number of mesh vertices is adjusted according to the offset. When the average coordinate of the offset is greater than or equal to the average coordinate of the original model, the number of mesh vertices is increased; otherwise, the number of mesh vertices is decreased.

[0025] Thirdly, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the three-dimensional geometric modeling method for aircraft wing structures described in the first aspect.

[0026] Fourthly, the present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and capable of running on the processor, wherein the processor executes the program to implement the steps of the three-dimensional geometric modeling method for aircraft wing structures described in the first aspect.

[0027] Fifthly, the present invention also provides a computer program product, the computer program product comprising a computer program, which, when executed by a processor, implements the steps of the three-dimensional geometric modeling method for aircraft wing structures described in the first aspect.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] In the iterative optimization process of the wing spars, wing ribs, and stringers in the initial model, this invention first determines the offset, then expands the original mesh vertices in the model along the normal direction to generate a new vertex set, and reconstructs the offset surface topology through triangulation. When reconstructing the offset surface topology, the number of mesh vertices is adjusted according to the offset to improve the model reconstruction quality. When the average coordinates after offset are greater than or equal to the average coordinates of the original model, the number of mesh vertices is increased; otherwise, the number of mesh vertices is reduced to improve the model reconstruction speed. While ensuring modeling efficiency, this invention solves the problem of reduced model accuracy after geometric reconstruction due to insufficient mesh partitioning. Attached Figure Description

[0030] The accompanying drawings, which form part of this embodiment, are used to provide a further understanding of this embodiment. The illustrative embodiments and their descriptions are used to explain this embodiment and do not constitute an improper limitation of this embodiment.

[0031] Figure 1This is a flowchart of the modeling method in Embodiment 1 of the present invention;

[0032] Figure 2 This is a schematic diagram of the modeling process in Embodiment 1 of the present invention;

[0033] Figure 3 This is a schematic diagram illustrating the layout of the wing main frame structure of Embodiment 1 of the present invention.

[0034] Figure 4 This is a rendering of the layout of the main wing frame structure of Embodiment 1 of the present invention;

[0035] Figure 5 This is a schematic diagram of the wing beam creation process in Embodiment 1 of the present invention;

[0036] Figure 6 This is a schematic diagram of the thickening process for the wing spars in Embodiment 1 of the present invention;

[0037] Figure 7 This is a schematic diagram of the tangents at both ends of the open side in Embodiment 1 of the present invention;

[0038] Figure 8 This is a schematic diagram of the included angle of the tangents in Embodiment 1 of the present invention;

[0039] Figure 9 This is a schematic diagram of auxiliary points in Embodiment 1 of the present invention;

[0040] Figure 10 This is a schematic diagram illustrating the creation effect of the wing spars in Embodiment 1 of the present invention;

[0041] Figure 11 This is a schematic diagram of the rough mold creation process for the wing ribs in Embodiment 1 of the present invention;

[0042] Figure 12 This is a schematic diagram of the roughing process optimization of the wing rib in Embodiment 1 of the present invention;

[0043] Figure 13 This is a schematic diagram of the segmentation effect during the creation of the wing ribs in Embodiment 1 of the present invention;

[0044] Figure 14 This is a schematic diagram of the wing stringer creation process in Embodiment 1 of the present invention;

[0045] Figure 15 This is a schematic diagram of the process of projecting a line onto a curved surface according to Embodiment 1 of the present invention;

[0046] Figure 16 This is a schematic diagram of the stringer sweeping solid formation algorithm of Embodiment 1 of the present invention;

[0047] Figure 17 This is a schematic diagram of the three-dimensional geometric model of the wing structure in Embodiment 1 of the present invention;

[0048] Figure 18 This is a schematic diagram of the three-dimensional geometric model of the skinned wing structure of Embodiment 1 of the present invention. Detailed Implementation

[0049] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0050] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0051] Example 1:

[0052] This embodiment provides a method for modeling a three-dimensional geometric model of an aircraft wing structure, such as... Figure 1 As shown, the method includes:

[0053] S1. Obtain the initial model of the aircraft wing; wherein, the initial model includes wing spars, wing ribs and stringers.

[0054] S2. Perform finite element simulation on the initial model of the aircraft wing. If the finite element simulation results meet the preset requirements, the final model is obtained; otherwise, the initial model is optimized.

[0055] S3. Iteratively optimize the design of the wing spars, wing ribs, and stringers in the initial model until the finite element simulation results meet the preset requirements. During the iterative optimization process, the offset is first determined. Then, the original mesh vertices in the model are expanded along the normal direction to generate a new vertex set. The offset surface topology is reconstructed through triangulation. When reconstructing the offset surface topology, the number of mesh vertices is adjusted according to the offset. If the average coordinates after the offset are greater than or equal to the average coordinates of the original model, the number of mesh vertices is increased; otherwise, the number of mesh vertices is decreased.

[0056] In some embodiments, the arrangement of aircraft structural components is based on the wing chord plane, with the main operational objects being wing spars, wing ribs, and stringers. For example... Figure 2 As shown, the overall implementation process includes the layout of the wing's main frame structure, creation of wing spars, wing ribs, stringers, finite element analysis of the model to evaluate the main performance of the structure, and iteration until the results meet the design requirements.

[0057] In some of the following embodiments, steps S1 to S3 include:

[0058] Wing main frame structure layout:

[0059] S3.1 In this embodiment, based on the wing skin and related evaluation data, mainly referring to load distribution, structural strength, aerodynamic shape, structural stiffness, etc., a preliminary two-dimensional layout of the wing main body structure is required to generate a preliminary version of the wing main body frame structure layout. For example... Figure 3 The diagram shows the drawing process for the layout. Optionally, the main wing frame structure layout is based on the wing chord plane, with lines for the spars, ribs, and stringers drawn on the plane. Simultaneously, the reference skin surface needs to be added to the scene.

[0060] In some embodiments, the effect of the wing main frame structure layout is as follows: Figure 4 As shown, the horizontal lines are the planar projection lines of the wing beams or girders, and the vertical lines are the planar projection lines of the wing ribs, which can be created using 3D software.

[0061] The projection line creation based on the wing chord plane proposed in this embodiment can dynamically modify the position and length of each projection line, and can also delete those that do not meet the requirements. It is flexible and easy to adjust.

[0062] In some embodiments, steps S2 and S3 include:

[0063] S3.2 Creation of the wing spars:

[0064] like Figure 5 As shown, in this embodiment, the wing spars are created automatically based on the wing's load distribution, structural strength requirements, and geometric parameters such as the spars' length, position, and thickness.

[0065] Optionally, first, based on the wing chord plane and the beam projection lines in the layout drawing, create multiple beam positioning planes perpendicular to the reference plane, with each plane perpendicular to the reference plane and tangent to the projection lines. Create planes on the reference plane, ensuring their size exceeds the maximum vertical height of the skin. For completed planes, thicken them according to thickness parameters to obtain the beam rough model. Divide the beam rough model using a reference skin surface to obtain the beam solids between the upper and lower wing surfaces. Repeat the above steps to create multiple wing spars. For example... Figure 6 As shown, the thickening process is as follows:

[0066] S3.2.1 Verification and suturing of curved surfaces:

[0067] Optionally, the correctness of the created beam station plane topology is checked. If it does not meet the closure requirements, it is stitched together. The number of edges of all topologies is calculated through stitching, using the following formula:

[0068] Total number of edges x2 = ∑ (number of edges of all faces).

[0069] S32.2 Thickening Offset Calculation: Offset calculation is performed for all vertices of the topology, using the following formula:

[0070] Left surface vertex coordinates for: ;

[0071] Right surface vertex coordinates for: ;

[0072] in, It is the normal vector; The initial topological vertex coordinates are used as the offset reference; For thickness.

[0073] S3.2.3 Geometric Reconstruction: The original mesh vertices are expanded along the normal direction to generate a new vertex set, and the offset surface topology is constructed using the Delaunay triangulation algorithm. Vertex stitching technology is used to process non-manifold boundaries, eliminating vertex spacing smaller than the tolerance threshold.

[0074] When reconstructing the offset surface topology, the coordinates of the surface vertices change. Therefore, directly using the original mesh vertices as the scatter set is not feasible. V There is a possibility that insufficient mesh partitioning may lead to a decrease in model accuracy after geometric reconstruction. This can be addressed by increasing the number of mesh vertices, but adding too many meshes will increase computational load and affect modeling efficiency. To balance model accuracy and modeling efficiency, this embodiment adjusts the number of mesh vertices based on the offset computational load. Optional options include:

[0075] ;

[0076] in, The number of new vertex sets generated by expanding the original mesh vertices along the normal direction; This represents the original number of mesh vertices; The average coordinates after model offset can refer to the average coordinates on a certain coordinate axis; This represents the average coordinates of the original model; and These are preset coefficients, which can be determined through experiments or other methods. When this occurs, it indicates that the model size needs to be increased. In this case, it is necessary to appropriately increase the number of mesh vertices to improve the model reconstruction quality. This indicates that the model size needs to be reduced, which requires appropriately reducing the number of mesh vertices to improve model reconstruction speed. While maintaining modeling efficiency, this solves the problem of reduced model accuracy after geometric reconstruction due to insufficient mesh coverage. The same method is used when reconstructing the offset surface topology of the ribs and stringers, and will not be detailed further below.

[0077] In some embodiments, the preset coefficient and When determining the value, the overall width of the offset surface and the original surface in the direction of large curvature change is compared to determine a ratio. This ratio is then calculated in the same way at multiple locations, and the average value is taken.

[0078] In some embodiments, and When it cannot be determined through experiments or other methods, it can be determined through screening. For example... and Values ​​range from 0 to 1 (excluding 0), based on the time taken in the finite element simulation step. =1 and When the value is 0.1, the time difference in simulation calculations is not significant (e.g., the time difference is less than or equal to 1 minute). The value can be directly set to 1; when =1 and When the value is 0.1, if the time difference in simulation calculation is large (e.g., the time difference is greater than 1 minute), then the comparison can continue. =0.9 and The simulation calculation time is calculated when the value is 0.1, until... Values ​​and When the value is 0.1, the simulation calculation time is not significantly different, thus determining... The value of .

[0079] Similarly, based on the time taken in the finite element simulation steps, when =0.1 and When =1, the time difference in simulation calculations is not significant (e.g., the time difference is less than or equal to 1 minute). The value can be directly set to 0.1; when =0.1 and When = 1, if the time difference in simulation calculation is large (e.g., the time difference is greater than 1 minute), then the comparison can continue. =0.2 and When =1, the simulation calculation time is used until... Values ​​and When =1, the simulation calculation time is not significantly different, therefore... The value of .

[0080] It should be noted that, under some complex curved surfaces, adjusting the number of network vertices based on the average of the coordinates of all or multiple coordinate points on the coordinate axis can have a certain impact on the calculation speed and the reflection of the true situation at the vertex (increasing the amount of computation). In this embodiment, the average of the coordinates of multiple coordinate points within a certain distance from the vertex position on the coordinate axis can be selected to improve the calculation speed and reflect the true situation of the vertex.

[0081] S3.2.4 Edge-Face Consistency Check: A boundary loop detection method is used to traverse all edge structures, and the edge sharing state is recorded using a hash table. For detected open edges, patch faces are automatically generated to ensure the thickened model meets the closure requirements. Fast collision detection is performed based on a spatial partitioning tree (BVH), and local mesh reconstruction is performed on patches that have penetrated each other. The least squares method is used to optimize and adjust vertex positions, eliminating self-intersections while maintaining curvature continuity.

[0082] In some embodiments, such as Figure 7 and Figure 8 As shown, when generating the patch, tangents are drawn at both ends of the open edge. If the two tangents coincide or the angle between the tangents is less than the preset angle value, the patch is directly generated; otherwise, as shown... Figure 9 As shown, auxiliary points are added at the open opening before surface patching. Optionally, the auxiliary points are located in the middle of the open opening. Adding auxiliary points can ensure the overall curvature of the model and maintain its accuracy.

[0083] Optionally, based on engineering practice, the preset included angle value is usually set to 5°~15° when modeling conventional models. The model in this embodiment is an aircraft wing structure, which belongs to a special scenario of aircraft wing structure and has higher accuracy requirements. The preset included angle value can be reduced to 1°~5°. When the included angle between two tangents is less than this range, the surface can be directly supplemented; otherwise, auxiliary points need to be added to maintain the curvature continuity.

[0084] To verify the preset angle values, finite element analysis can be used to analyze the stress distribution of the model under different preset angles, and the value that minimizes the strain gradient can be selected. Alternatively, a coordinate measuring machine can be used to detect the deviation between the patched area and the original model to determine a better preset angle value.

[0085] S3.2.5, Geometric Topological Stitching: The newly formed faces are topologically stitched together to create a 3D solid structure. The inner and outer structures generated by the offset are processed using the BSP (Binary Space Partitioning Tree) Boolean operation algorithm. By preprocessing to exclude non-intersecting faces, the computational complexity is reduced from O(n log n). The value is reduced to O(n log n).

[0086] The above thickening algorithm process maintains the geometric characteristics of the original model, reduces curvature error, and improves the accuracy of topological section closure.

[0087] The segmentation algorithm mentioned in the above process is as follows:

[0088] S3.2.6. The intersection line between the segmented surface and the solid is determined through Boolean operations to generate accurate intersection boundaries. At the same time, referring to parametric surface subdivision technology, the mesh is refined in the contact area between the segmented surface and the solid to maintain curvature continuity.

[0089] S3.2.7. Based on the intersection lines, the original entity is divided into multiple subdomains, and the reconstruction must preserve the edge and surface topology of the subdomains. Vertex stitching is performed on the open boundaries after segmentation, and local triangulation is used to reconstruct the mesh structure of the cut regions to ensure the closure of non-current boundaries.

[0090] By leveraging the precision of Boolean operations in the segmentation algorithm, the continuity of the top and bottom surfaces of the segmented entity with the higher-order skin surface is ensured, resulting in higher accuracy.

[0091] like Figure 10 As shown, this embodiment creates the top and bottom of the wing beam to meet the requirement of perfectly fitting the high-precision curved surface of the skin, making the finite element analysis in subsequent steps more accurate.

[0092] S3.3, Creation of the ribs:

[0093] Optionally, the geometric parameters of the ribs, such as thickness, can be defined based on the aerodynamic shape and structural requirements of the wing. For example... Figure 11 As shown, the rough rib model is created first, and then the solid is optimized by splitting the ribs and shelling the shell to create split ribs with multiple wing ribs in multiple positions.

[0094] S3.3.1 First, based on the wing chord plane and the rib projection lines in the layout drawing, create multiple rib positioning planes perpendicular to the reference plane, with each plane perpendicular to the reference plane and tangent to the projection lines. Create planes on the reference plane, ensuring their size exceeds the maximum vertical height of the skin. For completed planes, thicken them according to thickness parameters to obtain the rib rough model. Divide the rib rough model using a reference skin surface to obtain the rib solids between the upper and lower wing surfaces; repeat the above steps to create multiple rib rough models.

[0095] S3.3.2 The created rough mold for the wing ribs needs to be optimized. For example... Figure 12 As shown, the rib optimization process includes:

[0096] S3.3.2.1 First, perform a Boolean sum on each individual rib and intersecting individual spar to obtain a single solid. Then, segment the solid obtained in the previous step, using the sides of the spar as references, to complete the rib segmentation. Repeat the above steps to perform a Boolean sum and segment all intersections of ribs and spars. Finally, shell each rib individually according to its thickness parameters to generate a hollow structure, completing the rib creation. The result is as follows. Figure 13 As shown. The thickening, reconstruction, and segmentation algorithms used in the creation of the wing rib rough model are the same as those used in the creation of the wing beam, and will not be described in detail here.

[0097] Optionally, the Boolean summation algorithm during rib optimization is based on the BSP tree algorithm. This algorithm can effectively control the data rendering order, achieving rendering from back to front, and ensuring correct visibility and rendering effects. The entity segmentation algorithm during rib optimization differs from spar creation in that it preserves the calculation results; in rib optimization, entities on both sides of the segmentation surface are retained. The shelling algorithm during rib optimization requires first generating offset surfaces, offsetting them with uniform thickness, and then offsetting each retained surface by a fixed distance along the normal vector direction. This mainly includes planar and curved surface offsets.

[0098] Plane: The coordinates of the translated vertex are:

[0099] ax + by + cz +( d ± t ) = 0;

[0100] in, a Normal vector of the plane equation x Directional components, x for x To the variable; b Normal vector of the plane equation y Directional components, y for y To the variable; c Let z be the z-direction component of the normal vector of the plane equation. z for z To the variable; d The translation constant of the plane equation; t Let be the translational offset of the plane along the normal vector, when t When >0, the plane moves in the opposite direction to the normal vector. t When <0, the plane moves in the positive direction of the normal vector.

[0101] Surface: For a parametric surface, sample points are discrete according to the normal vector, and the surface is refitted after point-by-point offset. For parameters ( u , v ) surface points S ( u , v Its offset point is:

[0102] S '( u , v )= S ( u , v )+ · N ( u , v );

[0103] in, u Variables representing the horizontal dimension of the surface; v Variables representing the longitudinal dimension of the surface; The variable parameter represents the distance offset along the normal vector of the current position point; N It is the unit normal vector.

[0104] S3.3.2.2 Perform self-intersection detection and repair, discretize the offset surface into a triangular mesh, and use the AABB tree to accelerate the collision detection algorithm to detect penetration between meshes, improving detection efficiency. Then perform orientation control and coordinate system transformation to ensure that the normal vectors of all retained surfaces point to the same side.

[0105] S3.3.2.3 Finally, the entity is reconstructed using Boolean subtraction to perform the subtraction of the entity. This is implemented using a basic geometric algorithm based on a 3D software platform.

[0106] The rib creation implemented in this embodiment ensures a precise match between the internal cavity and the external geometry, and its boundaries better meet the requirements of the design data. The result is accurate, eliminating the need for multiple complex positioning operations and improving design efficiency.

[0107] S3.4, Long Truss Creation:

[0108] S3.4.1, such as Figure 14 As shown, based on the wing skin support and structural stiffness requirements, and using the wing root plane coordinate system, the cross-sectional shape and stringer geometric parameters such as width and height are defined. A cross-sectional sketch is created according to these parameters. Then, the stringer lines in the 2D layout are projected onto the upper and lower skin surfaces to generate projection lines. Next, a sweeping process is performed based on the cross-sectional sketch and projection lines to create a 3D solid stringer. This process is repeated for each stringer to complete the creation of the wing stringers.

[0109] S3.4.2, The process of projecting the stringers in the 2D layout drawing onto the upper and lower skin surfaces is as follows: Figure 15 As shown.

[0110] curve: C(t) = (x 0 + ·dx, y 0 + ·dy,z 0 + ·dz), t∈[0,1] ;

[0111] in, C ( t () represents the equation of the curve; The parameter variable represents the linear interpolation of the curve from the starting point to the ending point, and its value ranges from 0 to 1;x 0 represents the curve at x The offset in direction; dx The direction vector from the starting point to the ending point. x Quantity; y 0 represents the curve at offset in the y direction ; dy The direction vector from the starting point to the ending point. y Quantity; z 0 represents the curve at z The offset in direction; dz The direction vector from the starting point to the ending point. z Quantity.

[0112] Surface defined as z = f ( x , y ); the distance from the walk is △t Control precision; discretize the curve to form a set of points, and form a set of point sequences according to the step size { P i ( X i , Y i , Z i )},in, P i The step size point for the two-dimensional layout curve; X i step size point x value; Y i step size point y value; Z i step size point z value.

[0113] For each discrete point P i The formula for calculating its projection point on the curved surface is as follows: Q i ( X i , Y i , f ( X i , Y i (), connecting the intersection points forms a curve.

[0114] S3.4.3, The algorithm flow for creating entities based on the interface and path is as follows: Figure 16 As shown; when defining a section, follow the section type, for example, as TDefine the shape, its width, thickness, and height, and draw the cross-sectional view. Assume the two-dimensional cross-section is... C ( u ), u ∈[0,1], assuming the parameterized line is P ( t ), t ∈[0,1].

[0115] S3.4.4, Implementation of interpolation and coordinate transformation:

[0116] S3.4.4.1. Use uniform arc length sampling to sample the path. P ( t Discretize into n sampling points, { P 0, P 1,… P n}

[0117] S3.4.4.2, Request n Tangent at each sampling point T i and normal N i parameter.

[0118] S3.4.4.3 Place the cross section in the local coordinate system of the sampling point and calculate based on the initial cross section:

[0119] C i ( u )= P i + M i · C ( u );

[0120] in, M i It is a rotation and scaling matrix in the local coordinate system.

[0121] Mesh generation and topology stitching are performed using algorithms that reference geometric reconstruction, edge consistency checks, and topology stitching in beam creation, thus enabling the creation of the stringer entity.

[0122] The stringer creation implemented in this embodiment allows the upper surface of the stringer to completely fit the wing skin, with free path and high precision.

[0123] like Figure 17 and Figure 18 As shown, according to this embodiment, the creation of wing spars, ribs and stringers of the three-dimensional geometric model of the wing structure can be completed efficiently and flexibly. The skeleton position is controlled based on the two-dimensional drawing and a three-dimensional model is created, which puts forward a new idea for the design of aircraft wing structures.

[0124] This embodiment combines a 3D software platform to perform 3D modeling of the wing's main frame structure. It supports the creation of the structure after the main parameters are determined, and iterative modifications can be made quickly, which significantly improves the efficiency and accuracy of wing main modeling and enables rapid prototyping design.

[0125] Example 2:

[0126] This embodiment provides a three-dimensional geometric modeling system for aircraft wing structures, including:

[0127] The initial model acquisition module is configured to acquire the initial model of an aircraft wing;

[0128] The judgment module is configured to: perform finite element simulation on the initial model of the aircraft wing; if the finite element simulation results meet the preset requirements, the final model is obtained; otherwise, the initial model is optimized.

[0129] The optimization module is configured to iteratively optimize the design of the wing spars, wing ribs, and stringers in the initial model until the finite element simulation results meet the preset requirements. In the iterative optimization process of the wing spars, wing ribs, and stringers in the initial model, the offset is first determined, and then the original mesh vertices in the model are expanded along the normal direction to generate a new vertex set. The offset surface topology is reconstructed through triangulation. When reconstructing the offset surface topology, the number of mesh vertices is adjusted according to the offset. When the average coordinate of the offset is greater than or equal to the average coordinate of the original model, the number of mesh vertices is increased; otherwise, the number of mesh vertices is decreased.

[0130] The working method of the system is the same as the modeling method of the three-dimensional geometric model of the aircraft wing structure in Embodiment 1, and will not be repeated here.

[0131] Example 3:

[0132] This embodiment provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the three-dimensional geometric modeling method for aircraft wing structures described in Embodiment 1.

[0133] Example 4:

[0134] This embodiment provides an electronic device, including a memory, a processor, and a computer program stored in the memory and capable of running on the processor. When the processor executes the program, it implements the steps of the three-dimensional geometric modeling method for aircraft wing structures described in Embodiment 1.

[0135] Example 5:

[0136] This embodiment provides a computer program product, which includes a computer program. When the computer program is executed by a processor, it implements the steps of the three-dimensional geometric modeling method for aircraft wing structures described in Embodiment 1.

[0137] The above description is merely a preferred embodiment of this practice and is not intended to limit the scope of this practice. Various modifications and variations can be made to this practice by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this practice should be included within the protection scope of this practice.

Claims

1. A method for modeling a three-dimensional geometric model of an aerofoil structure, characterized in that, The method comprises the following steps: An initial model of an aircraft wing is obtained; Finite element simulation is performed on the initial model of the aircraft wing, and if the result of the finite element simulation meets preset requirements, a final model is obtained, otherwise, the initial model is optimized; The spar, rib and stringer in the initial model are iteratively optimized until the result of the finite element simulation meets the preset requirements; in the process of iteratively optimizing the spar, rib and stringer in the initial model, first, an offset is determined, then new vertex sets are generated by extending original grid vertices in the model along a normal direction to generate new vertex sets, the offset surface topology is reconstructed by triangulation, when reconstructing the offset surface topology, the number of grid vertices is adjusted according to the offset, when the average value of the offset coordinates is greater than or equal to the average value of the coordinates of the original model, the number of grid vertices is increased, otherwise, the number of grid vertices is decreased; the number of new vertex sets generated by extending the original grid vertices along the normal direction is: ； wherein, is the number of new vertex sets generated by extending the original mesh vertices along the normal direction; is the number of original mesh vertices; is the average value of the coordinates of the model after offset, indicating the average value of the coordinates on a certain coordinate axis; is the average value of the coordinates of the original model; and is a preset coefficient.

2. The method of claim 1, wherein, In the process of establishing and iteratively optimizing the spar model, based on the wing chord plane and the spar projection line in the layout diagram, a plurality of station planes are sequentially created perpendicular to the reference plane, the plane is created on the reference plane, for the completed plane, thickening is performed according to the thickness parameter to obtain a thick spar model; the thick spar model is segmented to obtain the spar entity between the upper and lower surfaces.

3. The method of claim 2, wherein, The correctness of the created spar station plane topology is checked, if the closed requirement is not met, the spar station plane topology is stitched; offset calculation is performed on all vertices of the topology, new vertex sets are generated by extending the original grid vertices along a normal direction, and the offset surface topology is constructed by using the Delaunay triangulation algorithm; all edge structures are traversed by using the boundary ring detection method, and the edge sharing state is recorded by using a hash table; the open edge is automatically supplemented by a patch; Fast collision detection is performed based on the space division tree, local grid reconstruction is performed on the penetrated patch; the position of the vertex is optimized and adjusted by using the least square method to eliminate self-intersection while maintaining curvature continuity; the newly formed surface is spliced to create a three-dimensional entity structure.

4. The method of claim 3, wherein the method further comprises: When the patch is supplemented, the tangent lines at both ends of the open edge are drawn, if the two tangent lines coincide or the included angle between the tangent lines is less than a preset included angle value, the patch is directly supplemented; otherwise, an auxiliary point is added at the open end, and then the patch is supplemented.

5. The method of claim 1, wherein, When the rib is optimized, first, a single rib and a single spar intersecting with the single rib are subjected to Boolean sum to obtain a single entity; then, the entity is segmented by taking the side surfaces on both sides of the spar as references to complete rib segmentation; finally, each rib is individually hollowed out according to the thickness parameter to generate a hollow structure, and the rib is created.

6. The method of claim 5, wherein the method further comprises: Self-intersection detection and repair are performed, the offset surface is discretized into a triangular mesh, the tree acceleration collision detection algorithm is used to detect the penetration between the meshes, and direction control and coordinate system transformation are performed to ensure that the normal vectors of all retained surfaces point to the same side; entity reconstruction is performed, and the Boolean subtraction operation is used to realize the subtraction of the body; when the stringer is created and optimized, the stringer line in the two-dimensional layout diagram is projected onto the upper and lower skin surfaces to generate a projection line, and then the projection line is scanned according to the cross-sectional sketch to create a three-dimensional stringer entity.

7. The method of claim 6, wherein the method further comprises: When the longeron is created and optimized, the projection point of each discrete point on the curved surface is calculated, the intersection points are connected to form a curve, and the entity is created based on the interface and the path.

8. The method of claim 7, wherein the method further comprises: When the longeron is created and optimized, interpolation and coordinate transformation are performed, including: the path is discretized into a plurality of sampling points by using arc length uniform sampling, and tangent and normal parameters of the plurality of sampling points are determined; and the section is placed into a local coordinate system of the sampling point.

9. A system for modeling a three-dimensional geometric model of an aircraft wing structure, the system comprising: The method comprises the steps that: An initial model acquisition module is configured to acquire an initial model of an aerofoil wing; A judgment module is configured to perform finite element simulation on the initial model of the aerofoil wing, and if the finite element simulation result meets preset requirements, a final model is obtained, otherwise, the initial model is optimized; An optimization module is configured to perform iterative optimization design on a spar, a rib and a longeron in the initial model until the finite element simulation result meets the preset requirements; wherein in the iterative optimization process of the spar, the rib and the longeron in the initial model, first, an offset is determined, then original grid vertices in the model are expanded to generate a new vertex set along a normal direction, a topological structure of an offset surface is reconstructed through triangulation, when the topological structure of the offset surface is reconstructed, the number of grid vertices is adjusted according to the offset, when an average value of the offset coordinates is greater than or equal to an average value of coordinates of the original model, the number of grid vertices is increased, otherwise, the number of grid vertices is reduced; the number of the new vertex set generated by the original grid vertices expanded along the normal direction is: ； wherein, is the number of new vertex sets generated by extending the original mesh vertices along the normal direction; is the number of original mesh vertices; is the average value of the coordinates of the model after the offset, indicating the average value of the coordinates on a certain coordinate axis; is the average value of the coordinates of the original model; and is a preset coefficient.

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