Method for quickly generating total finite element model based on geometric line and surface information

Abstract

The invention provides a method for quickly generating an overall finite element model based on geometric line and surface information. According to the method, on the basis of an open API interface of CAD and CAE software, arrangement of a geometric wireframe model can be rapidly completed in CAD, the geometric wireframe model is generated through a line-plane mesh algorithm, definition of information data such as corresponding attributes and materials is carried out on the geometric line-plane model, meshes are automatically divided through a finite element mesh algorithm, and the geometric wireframe model can be obtained. And extracting classification, attribute and material data of geometric lines and surfaces, establishing association with the divided grids, and generating a finite element grid model. According to the method for rapidly generating the overall finite element model based on the geometric line and surface information, the efficiency of converting the geometric line and surface information into the overall finite element model is improved, omission and errors are reduced, extra time, energy and manpower do not need to be spent, and the requirement for efficient and rapid design analysis of modern engineering can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of computer simulation, and particularly relates to a method for quickly generating an overall finite element model based on geometric line and surface information. Background Art

[0002] In the aircraft preliminary design stage, the geometric lines and surfaces of the main structure are mainly constructed by inputting the overall geometric shape in CAD software, and then imported into CAE software for finite element mesh generation, defining the classification, attributes and material data of the geometric line and surface model, and then establishing the attribute and material associations with the divided mesh, so as to obtain the overall finite element model.

[0003] Although the prior art has defined information such as the classification, attributes and materials of geometric lines and surfaces in CAD, due to the data incompatibility between different software, only the geometric model is often retained after being imported into CAE, and most of the originally defined geometric line and surface data are lost, and it is necessary to manually create and associate them with the geometric model one by one in CAE. The operation is cumbersome and requires a lot of manpower, energy and time. The efficiency of converting from geometric line and surface information to the overall finite element model is low, and it is easy to miss and make mistakes, which is difficult to meet the requirements of high-efficiency and rapid design and analysis in modern engineering. Summary of the Invention

[0004] The present invention provides a method for quickly generating an overall finite element model based on geometric line and surface information in view of the technical problems proposed in the above background art.

[0005] The present invention solves the above technical problems through the following technical solutions: The present invention provides a method for quickly generating an overall finite element model based on geometric line and surface information. The method includes: Invoking the CAD software interface to import the aerodynamic shape surface and structural skeleton information, automatically generating a geometric wireframe model including frames, beams, ribs, skins and stringers, and classifying the geometric wireframe into curves and surfaces based on the aerodynamic shape surface and the structural skeleton information; Directly defining the materials, coordinate systems, cross-sections and ply properties of the geometric wireframe model in the CAD software, wherein the curve geometry is defined as the coordinate system and the cross-section property, and the surface geometry is defined as the ply property; Automatically disconnecting the intersecting structures between the various structures in the geometric wireframe model through a line and surface mesh algorithm to generate a geometric line and surface model, and classifying it into the corresponding structural types; Importing the geometric line and surface model into the CAE software, and performing automated mesh generation according to the preset mesh size and dynamic adjustment strategy; Extract the classification, attributes, and material data of the geometric lines and surfaces in the geometric line and surface model through the CAD software, and associate the attributes and materials with the divided meshes; Export the obtained finite element model through the CAE software interface.

[0006] Preferably, the CAD software is CATIA, and the CATIA automatically generates the geometric wireframe model through its own API interface; the CAE software is Hypermesh software, and the finite element model is output through the interface of the Hypermesh software.

[0007] Preferably, the step of automatically disconnecting the intersecting structures between the various structures in the geometric wireframe model through the line and surface meshing algorithm further includes: Identify the intersecting structures between the frames, beams, and rib structures of the geometric wireframe model; Automatically disconnect the wireframe according to the geometric characteristics of the intersecting structures to generate several independent line and surface units; Several of the independent line and surface units constitute the geometric line and surface model.

[0008] Preferably, the specific operation of the line and surface meshing algorithm is as follows: Extract and organize each structure in the geometric wireframe model into a list of elements to be processed, extract one element to be processed from the list of elements to be processed, and cut the element to be processed; Cut the element to be processed according to the cutting logic to obtain the number of cutting results; Perform branch cutting according to the number of cutting results, classify the sub-units after the branch cutting into a geometric list, and remove the original geometric element that has been processed; Complete the cutting and classification of all the elements to be processed in the list of elements to be processed, end the operation, and generate the independent line and surface units.

[0009] Preferably, the cutting logic is that if the element to be processed has an intersecting relationship with other structures, then cut according to the intersecting area, generate sub-geometric units after cutting, and output the number of cutting results.

[0010] Preferably, the operation of performing branch cutting according to the number of cutting results further includes: If the number of cutting results is 0, there is no need to cut, and directly remove the element to be processed from the list of elements to be processed; If the number of cutting results is 1, generate one sub-geometric unit after cutting, and add the sub-geometric unit to the geometric list; If the number of cutting results is greater than 1, multiple sub-geometric units are generated after cutting, and it is determined whether combined cutting is to be performed.

[0011] Preferably, the operation of determining whether combined cutting is to be performed further includes: If the sub-geometric units need to be combined into a composite structure, the sub-geometric units are combined and then placed in the list to be processed.

[0012] If the sub-geometric units need to be processed independently, they are directly stored in the list to be processed.

[0013] Preferably, the step of automatically dividing the mesh according to the preset mesh size and the dynamic adjustment strategy further includes: Obtain the geometric lines and geometric surfaces of the geometric line-surface model, and cut the geometric surface along the normal direction of the geometric surface according to the geometric lines to obtain a mesh division model; Use the mesh division model to divide a two-dimensional mesh for the cut geometric surface according to the preset mesh size; Segment the geometric lines and divide a one-dimensional mesh for the segmented geometric lines; Merge the two-dimensional mesh and the one-dimensional mesh to obtain the divided mesh.

[0014] Preferably, the one-dimensional mesh division includes: Obtain the side lines corresponding to the geometric surfaces on each geometric line; Obtain the nodes on the side lines and store them as a set; Cut the geometric line according to the obtained nodes to segment the geometric line; Divide a one-dimensional mesh for the segmented geometric lines.

[0015] Preferably, the step of extracting the classification, attributes, and material data of the geometric lines and surfaces in the geometric line-surface model through the CAD software and associating the attributes and materials with the divided mesh further includes: Read the attribute file predefined in the CAD software, and extract the part material names and ply names of each part in the attribute file; Read the basic ply information and basic material parameters in the geometric line-surface model; Load the basic materials and basic plies predefined in the CAE software; Analyze the section parameters output by the CAD software, read the section parameters, and create section attributes corresponding to the section parameters; Bind the section attributes to the basic materials to form reusable primitive elements; Create a ply property with the same name as the part material name, and at the same time, copy and modify the name based on the primitive to obtain the part property; Associate the part property with the meshes with the divided attributes.

[0016] The positive and progressive effects of the present invention are as follows: The present invention provides a method for quickly generating an overall finite element model based on geometric line and surface information. The method of the present invention is based on the open API interfaces of CAD and CAE software, and can quickly complete the layout of the geometric wireframe model in CAD, generate the geometric wireframe model through the line and surface mesh algorithm, and define corresponding information data such as attributes and materials on the geometric line and surface model. Automatically divide the mesh through the finite element mesh algorithm, extract the classification, attributes and material data of the geometric line and surface, establish an association with the divided meshes, and generate a finite element mesh model. The method for quickly generating an overall finite element model based on geometric line and surface information of the present invention improves the efficiency of converting geometric line and surface information into an overall finite element model, reduces omissions and errors, does not require additional time, effort and manpower, and can meet the requirements of efficient and rapid design and analysis in modern engineering. Brief Description of the Drawings

[0017] Figure 1 It is a schematic flow chart of the method for quickly generating an overall finite model based on geometric line and surface information in Embodiment 1 of the present invention.

[0018] Figure 2 It is a schematic diagram of the cutting of the line and surface mesh algorithm in Embodiment 1 of the present invention.

[0019] Figure 3 It is a schematic specific flow chart of the cutting of the line and surface mesh algorithm in Embodiment 1 of the present invention.

[0020] Figure 4 It is a schematic flow chart of the automatic mesh division in Embodiment 1 of the present invention.

[0021] Figure 5 It is a schematic flow chart of the one-dimensional mesh division in the automatic mesh division in Embodiment 1 of the present invention.

[0022] Figure 6 It is a schematic specific flow chart of the attribute material association in step S5 in Embodiment 1 of the present invention.

[0023] Figure 7 It is a schematic diagram of the geometric wireframe model created based on the aircraft wing structure in Embodiment 1 of the present invention.

[0024] Figure 8 It is a schematic diagram of the geometric line and surface model created based on the aircraft wing structure in Embodiment 1 of the present invention.

[0025] Figure 9Schematic diagram of the finite element mesh model generated based on the aircraft wing structure in Embodiment 1 of the present invention. Detailed implementation manners

[0026] The present invention will be further described below by way of embodiments, but the present invention is not limited to the scope of the described embodiments.

[0027] Embodiment 1 As Figure 1 shown, this embodiment provides a method for quickly generating an overall finite model based on geometric line and surface information. The method includes: Step S1: Call the CAD software interface to import the aerodynamic shape surface and structural skeleton information, automatically generate a geometric wireframe model including frames, beams, ribs, skins, and stringers, and classify the curves and surfaces of the geometric wireframe based on the aerodynamic shape surface and structural skeleton information.

[0028] Step S2: Directly define the material, coordinate system, cross-section, and ply properties of the geometric wireframe model in the CAD software, where the curve geometry is defined as the coordinate system and cross-section properties, and the surface geometry is defined as the ply property.

[0029] Step S3: Automatically disconnect the intersecting structures between each structure in the geometric wireframe model through a line and surface meshing algorithm, generate a geometric line and surface model, and classify it into the corresponding structure types. In this embodiment, Step S3 further includes: identifying the intersecting structures between the frame, beam, and rib structures of the geometric wireframe model; automatically disconnecting the wireframe according to the geometric characteristics of the intersecting structure to generate a number of independent line and surface units; and the number of independent line and surface units constitutes the geometric line and surface model.

[0030] As an optional embodiment, the specific operation of the line and surface meshing algorithm is as follows: Extract and organize each structure (frame, beam, rib, skin, stringer) in the geometric wireframe model into a list to be processed, extract one geometric element to be processed from the list to be processed, and perform cutting on the geometric element to be processed; perform cutting on the geometric element to be processed according to the cutting logic to obtain the number of cutting results; perform branch cutting according to the number of cutting results, classify the sub-units after branch cutting into a geometric list, and remove the original geometric element that has been processed; complete the cutting and classification of all geometric elements to be processed in the list to be processed, and the operation ends to generate independent line and surface units. In this embodiment, the cutting logic is that if the geometric element to be processed has an intersecting relationship with other structures, it is cut according to the intersecting area, and sub-geometric units are generated after cutting, and the number of cutting results is output. Among them, the geometric list to be processed is divided into a 1D geometric list: storing one-dimensional geometric elements (such as the curves of beams and stringers); a 2D geometric list: storing two-dimensional geometric elements (such as the surfaces of skins); and a component intersection line list: recording the intersection lines between each component (such as the intersection points of beams and ribs), as Figure 2 shown.

[0031] As an optional embodiment, the operation of performing branched cutting according to the number of cutting results further includes: If the number of cutting results is 0, there is no need to perform cutting, and the geometric element to be processed is directly removed from the list of elements to be processed. If the number of cutting results is 1, only one sub-geometric unit is generated after cutting, and the sub-geometric unit is added to the geometric list. If the number of cutting results is greater than 1, multiple sub-geometric units are generated after cutting, and it is determined whether to perform combined cutting. In this embodiment, the operation of determining whether to perform combined cutting further includes: if the sub-geometric units need to be combined into a composite structure, the sub-geometric units are combined and then placed in the list of elements to be processed; if the sub-geometric units need to be processed independently, they are directly stored in the list of elements to be processed. Specifically, as Figure 3 shown, a geometric element M to be processed is extracted from the list of elements to be processed, and the geometric element M is cut; the number of cutting results N of the geometric element M after cutting is determined. If N = 0, there is no need to process it, and the geometric element M is removed from the list; if N = 1, a sub-unit is generated after cutting the geometric element M, then the original geometric element M and the generated sub-unit (i.e., the geometric element to be processed M = M + 1) are added to the list of elements to be processed; if N>1, multiple sub-units are generated after cutting, and it is further determined whether to perform combined cutting. The combined cutting conditions are as follows: if the sub-units need to be combined into a composite structure (such as the combined unit of the skin and stringer of an aircraft wing structure), select "Yes", then the combined unit and the original geometric element M (i.e., the geometric element to be processed M = M + 1) are added to the list of elements to be processed together; if the sub-units need to be processed independently (such as separate beam segments), select "No", then the original geometric element M and the sub-unit (i.e., the geometric element to be processed M = M + 1) are added to the list of elements to be processed together.

[0032] Step S4: Import the geometric line and surface model into the CAE software, and perform automated mesh generation according to the preset mesh size and dynamic adjustment strategy. As an optional embodiment, step S4 further includes: Step S41: Obtain the geometric lines and geometric surfaces of the geometric line and surface model, and cut the geometric surface along the normal direction of the geometric surface according to the geometric lines to obtain a mesh generation model.

[0033] Step S42: Use the mesh generation model to divide the cut geometric surface into two-dimensional meshes according to the preset mesh size.

[0034] Step S43: Segmentally cut the geometric lines and divide the cut geometric lines into one-dimensional meshes. In this embodiment, the one-dimensional mesh generation includes: Step S431: Obtain the edge lines of each geometric line corresponding to the geometric surface.

[0035] Step S432: Obtain the nodes on the edge lines and save them as a set.

[0036] Step S433: Segment the geometric line according to the obtained nodes to obtain segmented geometric lines.

[0037] Step S434: Divide one-dimensional meshes for the segmented geometric lines.

[0038] Step S44: Combine the two-dimensional meshes and one-dimensional meshes to obtain the divided meshes.

[0039] Step S5: Extract the classification, attributes, and material data of the geometric lines and surfaces in the geometric line and surface model through CAD software, and perform attribute and material association with the divided meshes.

[0040] As an optional embodiment, Step S5 further includes: Step S51: Read the attribute file predefined in CAD software, and extract the part material names and ply names of each part in the attribute file; Step S52: Read the basic ply information and basic material parameters in the geometric line and surface model.

[0041] Step S53: Load the basic materials and basic plies predefined in CAE software.

[0042] Step S54: Parse the section parameters output by CAD software, read the section parameters, and create section attributes corresponding to the section parameters.

[0043] Step S55: Bind the section attributes to the basic materials to form reusable primitives.

[0044] Step S56: Create ply attributes with the same name as the part material name, and at the same time copy and modify the name based on the primitive to obtain part attributes.

[0045] Step S57: Perform attribute and material association between the part attributes and the divided meshes.

[0046] Step S6: Export the obtained finite element model through the CAE software interface.

[0047] In this embodiment, the CAD software is CATIA, and CATIA automatically generates a geometric wireframe model through its own API interface; the CAE software is Hypermesh software, and the finite element model is output through the interface of Hypermesh software.

[0048] In this embodiment, the entire method is described by taking the aircraft wing structure as an example. Suppose there is an aerodynamic outer surface of an aircraft wing structure created by CATIA software, and the outer surface includes the geometric shape of the skin and the skeleton positions such as beams, ribs, and stringers. When processing using the method of this embodiment, first, a layout model is created by calling the CATIA software interface, the aerodynamic shape and skeleton data of the wing are read, and a geometric wireframe model of the wing structure is generated in CATIA, as Figure 7 shown. Its structural classification includes wing beams, wing ribs, stringers, skins, leading edge ribs, etc.; and according to the geometric data (including 1D and 2D geometries) of the geometric wireframe model, wire-surface meshing is performed to generate a geometric wire-surface model, as Figure 8 shown. The attributes, materials, and other data of the geometric wire-surface are quickly defined through the program interface. Then, by calling the interface of Hypermesh software, the geometric wire-surface model is imported, and preliminary meshing is performed using the wire-surface meshing algorithm; then, a structural classification corresponding to the geometric wire-surface model is established in CAE, and attributes (such as the cross-sectional dimensions of 1D flanges, the thickness of 2D webs, ply) and materials (such as the elastic modulus of steel, etc.) are assigned to each part mesh, and a general finite element mesh model for mechanical analysis is successfully generated, as Figure 9 shown. Through actual tests, compared with the traditional method, the method of this embodiment shortens the time by 90% from establishing the geometric wire-surface to generating the general finite element mesh model, and the analysis results are more accurate.

[0049] This embodiment provides a method for quickly generating a general finite model based on geometric wire-surface information. This method is based on the open API interfaces of CAD and CAE software, and can quickly complete the layout of the geometric wireframe model in CAD, generate the geometric wireframe model through the wire-surface meshing algorithm, define corresponding information data such as attributes and materials on the geometric wire-surface model, automatically divide the mesh through the finite element mesh algorithm, extract the classification, attributes, and material data of the geometric wire-surface, establish an association with the divided mesh, and generate a finite element mesh model. The method for quickly generating a general finite element model based on geometric wire-surface information of the present invention improves the efficiency of converting geometric wire-surface information into a general finite element model, reduces omissions and errors, does not require additional time, effort, and manpower, and can meet the requirements of efficient and rapid design and analysis in modern engineering.

[0050] Although the specific implementation manners of the present invention have been described above, those skilled in the art should understand that this is only an example, and the protection scope of the present invention is defined by the appended claims. Without departing from the principles and essence of the present invention, those skilled in the art can make various changes or modifications to these implementation manners, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A method for quickly generating a global finite element model based on geometric line and surface information, characterized in that, The method includes: Calling the CAD software interface to import the aerodynamic shape surface and structural skeleton information, automatically generating a geometric wireframe model including frames, beams, ribs, skins, and stringers, and classifying the curves and surfaces of the geometric wireframe based on the aerodynamic shape surface and the structural skeleton information; Directly defining the material, coordinate system, cross-section, and ply properties of the geometric wireframe model in the CAD software, where the curve geometry is defined as the coordinate system and the cross-section property, and the surface geometry is defined as the ply property; Automatically disconnecting the intersecting structures between the various structures in the geometric wireframe model through a wireframe and surface meshing algorithm, generating a geometric wireframe and surface model, and classifying it into corresponding structural types; Importing the geometric wireframe and surface model into the CAE software, and performing automated mesh generation according to a preset mesh size and dynamic adjustment strategy; Extracting the classification, properties, and material data of the geometric wireframe and surface in the geometric wireframe and surface model through the CAD software, and associating the properties and materials with the meshed grids; Exporting the obtained finite element model through the CAE software interface.

2. The method for rapidly generating an overall finite element model based on geometric line and surface information according to claim 1, wherein The CAD software is CATIA, and the CATIA automatically generates the geometric wireframe model through its own API interface; the CAE software is Hypermesh software, and the finite element model is output through the interface of the Hypermesh software.

3. The method for quickly generating an overall finite element model based on geometric line and surface information according to claim 1, characterized in that The step of automatically disconnecting the intersecting structures between the various structures in the geometric wireframe model through the wireframe and surface meshing algorithm further includes: Identifying the intersecting structures between the frames, beams, and ribs in the geometric wireframe model; Automatically disconnecting the wireframe according to the geometric characteristics of the intersecting structures to generate a number of independent wireframe and surface units; The number of independent wireframe and surface units constitutes the geometric wireframe and surface model.

4. The method for quickly generating a global finite element model based on geometric line and surface information according to claim 3, wherein The specific operation of the wireframe and surface meshing algorithm is as follows: Extracting and organizing each structure in the geometric wireframe model into a list of elements to be processed, extracting one element to be processed from the list of elements to be processed, and cutting the element to be processed; Cutting the element to be processed according to the cutting logic to obtain the number of cutting results; Performing branch cutting according to the number of cutting results, classifying the sub-units after the branch cutting into a geometric list, and removing the original element that has been processed; Completing the cutting and classification of all the elements to be processed in the list of elements to be processed, and the operation ends, generating the independent wireframe and surface units.

5. The method for quickly generating an overall finite element model based on geometric line and surface information according to claim 4, wherein The cutting logic is that if the element to be processed has an intersecting relationship with other structures, then cut according to the intersecting area, generate sub-geometric units after cutting, and output the number of cutting results.

6. The method for rapidly generating a global finite element model based on geometric line and surface information according to claim 5, wherein The operation of performing branch cutting according to the number of cutting results further includes: If the number of cutting results is 0, there is no need to cut, and directly remove the element to be processed from the list of elements to be processed; If the number of cutting results is 1, generate one sub-geometric unit after cutting, and add the sub-geometric unit to the geometric list; If the number of cutting results is greater than 1, generate multiple sub-geometric units after cutting, and determine whether to perform combined cutting.

7. The method for quickly generating an overall finite element model based on geometric line and surface information according to claim 6, characterized in that, The operation of determining whether to perform combined cutting further includes: If the sub - geometric units need to be combined into a composite structure, the sub - geometric units are combined and then placed in the list to be processed; If the sub - geometric units need to be processed independently, they are directly stored in the list to be processed.

8. The method for quickly generating an overall finite element model based on geometric line and surface information according to claim 1, characterized in that The steps of automatic mesh generation according to the preset mesh size and dynamic adjustment strategy further include: Obtain the geometric lines and geometric surfaces of the geometric line - surface model, and cut the geometric surface along the normal direction of the geometric surface according to the geometric lines to obtain a mesh generation model; Use the mesh generation model to divide the cut geometric surface into two - dimensional meshes according to the preset mesh size; Segment the geometric lines and divide the segmented geometric lines into one - dimensional meshes; Merge the two - dimensional meshes and the one - dimensional meshes to obtain the generated meshes.

9. The method for rapidly generating an overall finite element model based on geometric line and surface information according to claim 8, wherein The dividing of the one - dimensional meshes includes: Obtain the side lines corresponding to the geometric surface on each geometric line; Obtain the nodes on the side lines and store them as a set; Cut the geometric line according to the obtained nodes to segment the geometric line; Divide the segmented geometric lines into the one - dimensional meshes.

10. The method for rapidly generating an overall finite element model based on geometric line and surface information according to claim 1, wherein The steps of extracting the classification, attributes, and material data of the geometric lines and surfaces in the geometric line - surface model through the CAD software and performing attribute - material association with the generated meshes further include: Read the attribute files predefined in the CAD software and extract the part material names and ply names of each part in the attribute files; Read the basic ply information and basic material parameters in the geometric line - surface model; Load the basic materials and basic plies predefined in the CAE software; Analyze the cross - section parameters output by the CAD software, read the cross - section parameters, and create cross - section attributes corresponding to the cross - section parameters; Bind the cross - section attributes to the basic materials to form reusable primitive elements; Create ply attributes with the same name according to the part material names, and simultaneously copy and modify the names based on the primitive elements to obtain part attributes; Perform attribute - material association between the part attributes and the generated meshes.

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