Parametric modeling method of spatial structure node based on subdivision surface

Abstract

The application discloses a kind of space structure node parameterization modeling methods based on subdivision surface.The space structure node parameterization modeling method includes: using engineering modeling software to design and construct the control grid of space structure node;The control grid of the space structure node constructed is subdivided processing;Parameterization operation is carried out to the space structure node subdivision surface;The engineering modeling software is Grasshopper software.The space structure node parameterization modeling method of the application can generate space structure node models with different shapes and characteristics according to different parameter values, and the surface of the node model is smooth and continuous without obvious sharp corners and geometric discontinuity. It has morphological diversity and aesthetic appeal, reducing the fatigue damage risk of space structure nodes.

Description

Technical Field

[0001] This invention relates to a spatial structure node modeling technique, and more particularly to a parametric modeling method for spatial structure nodes based on subdivided surfaces. Background Technology

[0002] Spatial structural nodes are crucial components connecting the members of a spatial structure, influencing both its mechanical properties and aesthetic appearance. Traditional nodes are typically formed by directly welding several members together or by connecting them with bolts using transition pieces.

[0003] The current problem is:

[0004] 1) The nodes have a large number of sharp corners and geometric discontinuities, which makes them difficult to manufacture, affects their aesthetics, and reduces their mechanical properties;

[0005] 2) A large number of intersecting welds will generate high residual stress, resulting in significant stress concentration in the nodal area. Under cyclic loads, fatigue failure is likely to occur, threatening the structural safety.

[0006] 3) In order to prevent stress concentration defects, the nodes of the spatial structure should be designed with smooth and continuous surfaces as much as possible. However, traditional manual computer-aided modeling methods have disadvantages such as complex calculations, low accuracy, and low efficiency. Summary of the Invention

[0007] The purpose of this invention is to provide a parametric modeling method for spatial structure nodes based on subdivided surfaces.

[0008] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0009] A parametric modeling method for spatial structure nodes based on subdivided surfaces, the parametric modeling method for spatial structure nodes includes:

[0010] The control mesh for spatial structure nodes is designed and constructed using engineering modeling software;

[0011] The control mesh of the constructed spatial structure nodes is subdivided.

[0012] Perform parametric operations on the subdivision surfaces of spatial structure nodes.

[0013] Furthermore, the engineering modeling software is Grasshopper.

[0014] Furthermore, the specific implementation method of designing and constructing the control mesh for spatial structure nodes using engineering modeling software includes:

[0015] Open the Rhino software and create a new file based on the Grasshopper parametric platform;

[0016] In Grasshopper, the Number Slider component is used to dynamically define the configuration control parameters of spatial structure nodes, and the configuration control parameters are connected to the Curve component that describes the geometric configuration of the spatial structure nodes.

[0017] When the geometry of the target spatial structure node changes, the Move, Rotate, and Scale components are used to perform geometric transformation operations on the basic geometric model of the spatial structure node, and a control mesh is generated based on the configuration control parameters.

[0018] Furthermore, the specific method for subdividing the control mesh of the constructed spatial structure nodes includes:

[0019] In Grasshopper, the Subd component is used to subdivide the control mesh for spatial structure nodes;

[0020] Add a new vertex to each polygon face on the spatial structure node control grid. The new vertex is the average position of all vertices on the polygon face in which it is located.

[0021] Add a new vertex to each edge of the polygon. The new vertex is the average position of the two vertices at the two ends of the edge and the two adjacent face vertices.

[0022] Adjust the positions of all existing vertices in the control mesh so that their positions are the average of their original positions and the positions of all newly added face vertices and edge vertices.

[0023] Connect all newly generated vertices to form a quadrilateral mesh;

[0024] Repeat the above steps until the subdivision convergence limit is reached, forming the spatial structure node limit subdivision surface.

[0025] Furthermore, the specific method for parametrically subdividing the spatial structure node surface includes:

[0026] In Grasshopper, the Evaluate Surface, Curvature, and Thickness components are used to evaluate and analyze the subdivision surfaces of spatial structure nodes, obtain the accuracy, curvature, and thickness data of the subdivision surfaces, and export the above data as output parameters to Rhino.

[0027] In Grasshopper, the Number Slider, Graph Mapper, and Range components are used to dynamically define and adjust the parameters of the subdivision surfaces of spatial structure nodes, and these parameters are connected to the algorithm program for geometric modeling of spatial structure nodes.

[0028] In Grasshopper, the Offset Surface, Trim Surface, and Extrude Surface components are used to deform and trim the subdivision surfaces of spatial structure nodes. The final spatial structure node model is generated based on the parameter values, and the subdivision surface model can be previewed and modified in real time.

[0029] Furthermore, the geometric dimensions of the constructed control grid are determined by six configuration control parameters: chord diameter, web member to chord diameter ratio, in-plane angle between web member and chord member, out-of-plane angle between web member and chord member, effective chord member length, and effective web member length.

[0030] Furthermore, the subdivision of the control mesh of the constructed spatial structure nodes is achieved by recursively refining and smoothing the control mesh to generate a high-precision and high-quality surface model of the spatial structure nodes.

[0031] The recursive algorithm used to refine and smooth the control mesh is the Catmull-Clark subdivision algorithm.

[0032] In the parametric modeling method for spatial structure nodes of the present invention, subdivision surface technology is used to realize the geometric form of spatial structure nodes. Since the node surface designed based on subdivision surface technology is smooth and continuous, the shape is beautiful and simple, and the force transmission path is clear, the problem 1 mentioned in the background technology is solved: "The nodes have a lot of sharp corners and geometric discontinuities, which makes manufacturing difficult, affects the aesthetics, and reduces the mechanical performance of the nodes."

[0033] In the parametric modeling method for spatial structure nodes of the present invention, the subdivision surface technology is used to realize the geometric form of the spatial structure nodes. Since the direct intersection of the members is avoided, the connection area is set at a position far away from the core of the node, thereby solving the problem 2 mentioned in the background technology: "A large number of cross welds in the connection area will generate high residual stress, resulting in significant stress concentration in the node domain, which is prone to fatigue failure under cyclic loads".

[0034] The parametric modeling method for spatial structure nodes in this invention employs parametric geometric modeling technology, using a visual programming language to create and control complex geometric models. This solves problem 3 mentioned in the background art: "Traditional manual computer-aided modeling methods suffer from drawbacks such as computational complexity, low accuracy, and low efficiency." Attached Figure Description

[0035] Figure 1 A flowchart illustrating a specific implementation of the parametric modeling method for spatial structure nodes based on subdivided surfaces according to the present invention;

[0036] Figure 2 A schematic diagram showing the dimensioning of a typical spatial structure node;

[0037] Figure 3 A schematic diagram of a double-layer upright quadrangular pyramidal space frame employing spatial structural nodes;

[0038] Figure 4 A schematic diagram of spatial structure node models of different sizes generated parametrically based on subdivision surface technology. Detailed Implementation

[0039] The present invention will be further illustrated below with specific embodiments:

[0040] This embodiment provides a parametric modeling method for spatial structure nodes based on subdivided surfaces. This method can be used to design smooth and continuous spatial structure nodes.

[0041] See Figure 1 The spatial structure node parametric modeling method of this embodiment includes:

[0042] S1 uses engineering modeling software to design and construct the control mesh for spatial structure nodes.

[0043] The control grid established in step S1 can be regarded as an initial control grid, and subsequent structural design control is based on this control grid.

[0044] The established control grid is a geometric grid composed of polygons, which determines the topology and shape characteristics of the subdivision surface.

[0045] Specifically

[0046] See Figure 2 The geometric dimensions of the established control grid are mainly determined by six configuration control parameters, which are as follows:

[0047] The diameter of the chord is denoted by d0;

[0048] The ratio of the diameter of the web member to the diameter of the chord member is denoted by β, and β = d1 / d0, where d1 represents the diameter of the web member and d0 represents the diameter of the chord member.

[0049] The angle between the web member and the chord member in the plane is denoted by θ. i To indicate;

[0050] The out-of-plane angle between the web member and the chord member is denoted by θ0;

[0051] The effective chord length is denoted by l0;

[0052] The effective length of the web member is denoted by l1.

[0053] Typical node dimensions are as follows Figure 2 As shown.

[0054] The six configuration control parameters mentioned above, as input parameters for describing the geometric configuration of spatial structure nodes based on subdivision surface technology, can be adjusted according to different types and requirements of spatial structure nodes to meet different design needs and conditions.

[0055] In this embodiment, the engineering modeling software used to design and construct the spatial structure node control grid is Grasshopper, which is a mature software with existing technology.

[0056] The control mesh for designing and constructing spatial structure nodes is designed using Grasshopper software, and its specific operation process includes S11 to S13.

[0057] S11, open the pre-configured Rhino software, and create a new file based on the Grasshopper parametric platform.

[0058] S12, in Grasshopper, uses the Number Slider component to dynamically define six configuration control parameters for spatial structure nodes: chord diameter d0, web member to chord diameter ratio β, and in-plane angle θ between web member and chord member. i The six configuration control parameters—the out-of-plane angle θ0 between the web members and the chord members, the effective chord member length l0, and the effective web member length l1—are connected to the Curve component, which describes the geometric configuration of the spatial structure node, thereby creating the basic geometric model of the spatial structure node.

[0059] S13, when the geometric shape of the target spatial structure node changes, the Move, Rotate, and Scale components are used to perform geometric transformation operations on the basic geometric model of the spatial structure node created in step S12. A control mesh is generated based on the six configuration control parameters, and the changes in the control mesh are observed in real time. The process continues until a smooth and even surface of the target spatial structure node without geometric abrupt changes is constructed, thus completing the "construction of the control mesh for the spatial structure node".

[0060] S2, further subdivide the spatial structure node control mesh constructed in step S1.

[0061] Specifically

[0062] The control mesh is refined and smoothed using existing recursive algorithms to generate high-precision and high-quality spatial structure nodal surface models.

[0063] In this embodiment, the recursive algorithm used to refine and smooth the control mesh is the Catmull-Clark subdivision algorithm.

[0064] In this embodiment, the process of refining and smoothing the control grid includes S21 to S26.

[0065] S21, in Grasshopper, uses the Subd component to subdivide the control mesh for spatial structure nodes.

[0066] S22, add a new vertex to each polygon face on the spatial structure node control grid, the new vertex being the average position of all vertices on its polygon face.

[0067] S23, add a new vertex to each polygon edge, the new vertex being the average position of the two vertices at the two ends of the edge and the two adjacent face vertices.

[0068] S24 adjusts the positions of all existing vertices in the control mesh so that their positions are the average of their original positions and the positions of all newly added face vertices and edge vertices.

[0069] S25 connects all newly generated vertices into a quadrilateral mesh.

[0070] S26. Repeat steps S21 to S25 until the subdivision convergence limit is reached, thus finally forming the spatial structure node limit subdivision surface.

[0071] S3. For the spatial structure nodes processed in step S2, perform parameterization operations on the subdivided surfaces after subdivision processing.

[0072] It should be noted that parametric operation refers to the process of creating and controlling complex geometric models through a visual programming language. This allows for the parametric design and modification of geometric models, enabling flexible adjustment and transformation of subdivision surface configurations.

[0073] In this embodiment, Grasshopper software is used to perform parametric operations on the subdivision surface.

[0074] Specifically, the parametric operation process for subdivided surfaces is as follows: S31 to S33.

[0075] S31. In Grasshopper, the Evaluate Surface, Curvature, and Thickness components are used to evaluate and analyze the subdivided surface of the spatial structure node after step S2, and obtain data such as the accuracy, curvature, and thickness of the subdivided surface. The above data is then exported to Rhino as output parameters.

[0076] The Evaluate Surface component is used to evaluate and analyze the subdivision surface of the spatial structure nodes after step S2 to obtain the accuracy of the subdivision surface;

[0077] The Curvature component is used to evaluate and analyze the subdivision surface of the spatial structure node after step S2, and the curvature of the subdivision surface is obtained.

[0078] The Thickness component is used to evaluate and analyze the subdivision surface of the spatial structure node after step S2, and the thickness of the subdivision surface is obtained.

[0079] In S32, Grasshopper uses components such as Number Slider, Graph Mapper, and Range to dynamically define and adjust the parameters of the spatial structure node subdivision surface obtained in step S31, such as surface accuracy, curvature, and thickness, and connects these parameters to the algorithm program for geometric modeling of spatial structure nodes.

[0080] S33, in Grasshopper, uses components such as Offset Surface, Trim Surface, and Extrude Surface to deform and trim the subdivision surfaces of spatial structure nodes, generates the final spatial structure node model based on parameter values, and allows for real-time preview and modification of the subdivision surface model.

[0081] See Figure 3 In that Figure 3 The paper takes a double-layer upright quadrangular pyramidal space frame as an example to demonstrate the implementation effect of the technical solution of this embodiment, and completes the parametric modeling of spatial structure nodes based on subdivision surface technology.

[0082] See Figure 4 In that Figure 4 The image shows spatial structure node models of different sizes generated parametrically based on subdivision surface technology.

[0083] The parametric modeling method for spatial structure nodes in this embodiment can generate spatial structure node models with different shapes and features based on different parameter values. The surface of the node model is smooth and continuous, without obvious sharp corners or geometric discontinuities, and has morphological diversity and aesthetics, reducing the risk of fatigue damage to spatial structure nodes.

[0084] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A parametric modeling method for spatial structure nodes based on subdivided surfaces, characterized in that, The spatial structure nodes are local connection nodes between chord members and web members. The method is implemented in Rhino software based on the Grasshopper parametric platform and includes: S1. Constructing the control mesh for spatial structure nodes: Dynamically define the chord diameter d0, the ratio β between the web member and the chord diameter, and the in-plane angle θ between the web member and the chord using the Number Slider component. i The out-of-plane angle θ between the web member and the chord member o Six configuration control parameters are defined, including effective chord length l0 and effective web length l1, where β = d1 / d0, and d1 is the web diameter. These six configuration control parameters are connected to the Curve component, which describes the geometric configuration of the spatial structure node, to create a basic geometric model of the spatial structure node. When the geometry of the target spatial structure node changes, the Move, Rotate, and Scale components are used to perform geometric transformations on the basic geometric model, and a control mesh composed of polygons is generated based on the six configuration control parameters. This control mesh is used to determine the topology and shape characteristics of the subdivided surface. S2. Generate the spatial structure node limit subdivision surface: In Grasshopper, using the Subd component, recursively execute steps S21 to S25 on the control mesh according to the Catmull-Clark subdivision algorithm: S21. Add a new vertex to each polygonal face of the control grid, the new vertex being located at the average position of all vertices of the polygonal face in which it resides; S22. Add a new vertex to each polygonal edge of the control grid, the new vertex being located at the average position of the two end vertices of the edge and the two adjacent face vertices; S23. Adjust the position of each original vertex of the control mesh so that the adjusted position of the original vertex is the average position of its original position and all adjacent newly added face vertices and edge vertices. S24. Connect the newly generated vertices and the adjusted original vertices to form a quadrilateral mesh; S25. Repeat steps S21 to S24 for the quadrilateral mesh until the subdivision convergence limit is reached to obtain the spatial structure node limit subdivision surface. S3. The Evaluate Surface, Curvature, and Thickness components are used to evaluate the subdivision surface of the spatial structure node, obtaining accuracy, curvature, and thickness data, which are then output to Rhino. The Number Slider, GraphMapper, and Range components are used to dynamically define and adjust the accuracy, curvature, and thickness parameters, and the adjusted parameters are connected to the algorithm program for geometric modeling of the spatial structure node. Then, the Offset Surface, Trim Surface, and Extrude Surface components are used to deform and trim the subdivision surface of the spatial structure node according to the adjusted parameters, generating the final spatial structure node model, which can be previewed and modified in real time. The final spatial structure node model avoids direct intersection of members and sets the connection area away from the node core. The surface of the spatial structure node model is smooth, continuous, and without obvious sharp corners or geometric discontinuities.

2. The method for parametric modeling of spatial structure nodes based on subdivided surfaces according to claim 1, characterized in that, In step S1, the six configuration control parameters are adjusted according to the type and design requirements of the spatial structure nodes, and the changes of the control mesh are observed in real time until a target spatial structure node control mesh with a smooth surface and no geometrical abrupt changes is constructed.

3. The method for parametric modeling of spatial structure nodes based on subdivided surfaces according to claim 1, characterized in that, In step S3, the accuracy of the spatial structure node's limit subdivision surface is obtained using the Evaluate Surface component, the curvature of the spatial structure node's limit subdivision surface is obtained using the Curvature component, and the thickness of the spatial structure node's limit subdivision surface is obtained using the Thickness component. The accuracy, curvature, and thickness are then connected as parameters to be adjusted to the algorithm program for geometric modeling of the spatial structure node.

4. The method for parametric modeling of spatial structure nodes based on subdivided surfaces according to any one of claims 1 to 3, characterized in that, The spatial structure node is the connection node between the chord and web members in a double-layer upright quadrangular pyramidal space frame.

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