Wire frame type flexible body MNF file generation method and device, equipment and medium

Abstract

The invention relates to the technical field of simulation, and discloses a wire frame type flexible body MNF file generation method and device, equipment and a medium, and the method comprises the steps: loading a to-be-analyzed part geometric model, and carrying out the mesh generation of the part geometric model, and obtaining a mesh unit; selecting key nodes related to modal analysis from the grid units on the basis of geometric features of the geometric model of the part; connecting the key nodes by using a virtual connection unit until a complete wireframe type structure is formed; and performing modal analysis on the wireframe type structure, and outputting an analysis result as the wireframe type flexible body MNF file. According to the technical scheme provided by the invention, the process of generating the MNF file can be optimized, and the calculation time, the file volume and the operation complexity are reduced.

Description

Technical Field

[0001] The present application relates to the field of simulation technology, and in particular to a method, device, equipment and medium for generating a wireframe flexible body MNF file. Background Art

[0002] The current traditional method generates a mesh model through finite element analysis and converts the modal frequency and modal vibration shape data into an MNF file. This usually requires multiple file conversions. The generated MNF files are large in size, take a long time to calculate, and are cumbersome to operate. Especially when dealing with large-scale and complex models, this puts great pressure on storage, computing efficiency, and memory consumption.

[0003] Therefore, how to optimize the process of generating MNF files and reduce computing time, file size and operation complexity is a technical problem that needs to be solved urgently. Summary of the Invention

[0004] The present application provides a method, apparatus, device and medium for generating a wireframe flexible body MNF file, which achieves the technical effect of optimizing the process of generating MNF files, reducing calculation time, file size and operation complexity.

[0005] In order to achieve the above objectives, the main technical solutions adopted in this application include: In a first aspect, an embodiment of the present application provides a method for generating a wireframe flexible body MNF file, the method comprising: loading a component geometric model to be analyzed, and meshing the component geometric model to obtain mesh units; Based on the geometric features of the component geometric model, key nodes related to modal analysis are selected from the grid elements; the key nodes are connected using virtual connection elements until a complete wireframe structure is formed; A modal analysis is performed on the wireframe structure, and the analysis result is output as the wireframe flexible body MNF file.

[0006] This embodiment provides a method for generating a wireframe flexible body MNF file. By loading the component geometry model and performing meshing, the component geometry is converted into a discrete mesh suitable for modal analysis, providing a basis for subsequent calculations. By selecting key nodes related to modal analysis and processing only important parts, unnecessary nodes and elements are avoided, thereby reducing the amount of calculation and saving calculation time. At the same time, the key nodes are connected through virtual connection units to form a wireframe structure. Compared with the traditional full three-dimensional structure, the number of elements and nodes is reduced, making the generated MNF file smaller. The modal analysis results are output as a streamlined wireframe flexible body MNF file, which further optimizes the file structure and reduces redundant data. Overall, it not only reduces the calculation time and file size, but also simplifies the operation complexity and improves the overall analysis efficiency.

[0007] In one embodiment, the selecting key nodes related to modal analysis from the grid elements based on the geometric features of the component geometric model includes: Marking nodes corresponding to the grid units according to the geometric features of the component geometric model; According to the analysis type of the modal analysis, the marked nodes are screened to obtain key nodes related to the modal analysis.

[0008] This embodiment can improve modeling accuracy by marking key nodes according to the geometric characteristics of the parts, ensuring that no important parts are missed in subsequent analysis. This not only optimizes the accuracy of finite element analysis, but also effectively reduces unnecessary errors. By screening out key nodes related to modal analysis, the amount of calculation can be greatly reduced, the analysis efficiency can be improved, and the accuracy of the results can be improved. The screened nodes help to focus on the most critical parts of the structure, such as stress concentration points or support points, thereby improving the accuracy of local analysis and reducing unnecessary computational burdens.

[0009] In one embodiment, the virtual connection unit adopts a Plotel unit; and the step of connecting the key nodes using the virtual connection unit until a complete wireframe structure is formed includes: The key nodes are connected using the Plotel units until a complete wireframe structure is formed; wherein each Plotel unit represents a virtual connection between two key nodes.

[0010] In one embodiment, before forming the complete wireframe structure, the method further comprises: receiving analysis parameters for defining the component geometry model; wherein the parameters include element type, material properties, and boundary conditions; Accept the selected Plotel option so that Plotel elements are used when performing modal analysis; Receive the selection of the NORIGID option so that the Plotel element is used as a flexible element when performing a modal analysis.

[0011] This embodiment provides an accurate description and analysis basis for the component geometry model by receiving and defining analysis parameters (such as unit type, material properties and boundary conditions). These parameters enable modal analysis to truly reflect the dynamic response of the component under vibration conditions. Then, the Plotel unit is introduced as a virtual unit to simplify the calculation process while retaining the overall dynamic characteristics of the structure, significantly improving the calculation efficiency. Finally, the NORIGID option ensures that the Plotel unit participates in the analysis as a flexible unit rather than a rigid unit, making the modal analysis results more accurate, especially when dealing with the dynamic behavior of complex structures, and being able to better capture the vibration characteristics.

[0012] In one embodiment, performing modal analysis on the wireframe structure includes: Constructing a stiffness matrix based on the material properties and the element shape function of the mesh element; constructing a mass matrix based on the material properties and unit volume of the grid unit; Adjusting the stiffness matrix and the mass matrix according to the boundary conditions in the component geometric model to obtain a target stiffness matrix and a target mass matrix; Based on the target stiffness matrix and the target mass matrix, an eigenvalue equation is constructed, and the eigenvalue equation is solved to obtain analysis results including modal frequencies and modal vibration shapes.

[0013] This embodiment constructs a stiffness matrix using the material properties and shape functions of the mesh elements to ensure that the stiffness of the structure is consistent with the actual situation. Then, combining the material properties and volume, a mass matrix is ​​constructed to simulate the mass distribution and inertial characteristics of the structure. On this basis, the stiffness matrix and mass matrix are modified by adjusting the boundary conditions to ensure that the calculation results are consistent with the actual constraints. Finally, the eigenvalue equation is solved to obtain the modal frequencies and modal vibration shapes. This ensures that the subsequently generated MNF file only contains the necessary dynamic characteristics, avoiding redundant data and thus reducing the file size.

[0014] In one embodiment, adjusting the stiffness matrix and the mass matrix according to the boundary conditions in the component geometric model to obtain a target stiffness matrix and a target mass matrix includes: extracting fixed end nodes in the boundary conditions; For each fixed end node, delete the row and column corresponding to each fixed end node in the stiffness matrix to obtain the target stiffness matrix; For each fixed end node, the row and column corresponding to each fixed end node in the mass matrix are deleted to obtain the target mass matrix.

[0015] This embodiment extracts the fixed-end nodes from the boundary conditions and deletes the rows and columns corresponding to these fixed-end nodes from the stiffness matrix. Because these rows and columns do not affect the structural deformation, deletion significantly reduces the computational effort, thereby improving efficiency. Similarly, rows and columns associated with fixed-end nodes should be deleted from the mass matrix to avoid unnecessary mass contributions. This reduces the size of the matrix, conserves computing resources, reduces memory usage, and speeds up modal analysis. Ultimately, the resulting MNF file is smaller, easier to store and transfer, and simpler to operate.

[0016] In one embodiment, after obtaining the grid unit, the method further includes: Detecting the material density units used in the component geometry model and comparing them with the material density units preset in the simulation software; If the material density unit used is inconsistent with the preset material density unit, the material density unit used is corrected to make the material density unit used consistent with the preset material density unit.

[0017] This embodiment ensures the consistency of material density units by detecting the material density units used in the component geometry model and comparing them with the preset material density units in the simulation software. This avoids calculation errors caused by inconsistent units and improves the accuracy and reliability of simulation analysis. If inconsistent material density units are found, corrections are made to align them with the preset material density units. This not only eliminates errors caused by inconsistent units but also ensures the accuracy of simulation results.

[0018] In a second aspect, an embodiment of the present application provides a device for generating a wireframe flexible body MNF file, the device comprising: a mesh division unit for loading a component geometric model to be analyzed and meshing the component geometric model to obtain mesh units; Selecting node elements, for selecting key nodes related to modal analysis from the mesh elements based on geometric features of the component geometric model; a wireframe forming unit, configured to connect the key nodes using virtual connection units until a complete wireframe structure is formed; The modal analysis unit is used to perform modal analysis on the wireframe structure and output the analysis result as the wireframe flexible body MNF file.

[0019] In a third aspect, an embodiment of the present application provides a computer device, including: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the above-mentioned method for generating a wireframe flexible body MNF file by executing the computer instructions.

[0020] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, on which computer instructions are stored, and the computer instructions are used to enable a computer to execute the above-mentioned method for generating a wireframe flexible body MNF file. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0022] Figure 1 A flowchart of a method for generating a wireframe flexible body MNF file provided in an embodiment of the present application; Figure 2 Flowchart of step S3 provided in the embodiment of the present application; Figure 3 A flowchart before forming a complete wireframe structure provided in an embodiment of the present application; Figure 4 A flowchart of modal analysis of a wireframe structure provided in an embodiment of the present application; Figure 5 A flowchart of step S75 provided in an embodiment of the present application; Figure 6 A flowchart after obtaining a grid unit is provided in an embodiment of the present application; Figure 7 A block diagram of a wireframe flexible body MNF file generation device provided in an embodiment of the present application; Figure 8 A schematic diagram of the structure of a computer device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0023] To make the purpose, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of this application.

[0024] In current engineering analysis, generating a flexible body MNF (Modal Neutral File) file involves first generating a mesh model of the structure through finite element analysis. Then, based on this mesh, the structure's modal frequencies, mode shapes, and other information are calculated, and this data is finally converted into an MNF file. During this process, tools such as Flex Tools are often used to generate intermediate h3D files, which are then converted into the final MNF format. This method relies on complex modal analysis and multiple file conversions, which are cumbersome and require significant computing resources for efficient analysis and conversion. Furthermore, the generated MNF files are often very large, reaching hundreds of megabytes or even several gigabytes in size. This phenomenon is particularly pronounced when dealing with large, complex models, especially those involving high-frequency modes or complex geometries. The resulting file size not only increases storage requirements but also significantly impacts computational efficiency and memory consumption.

[0025] Furthermore, traditional methods often require significant computational time to generate and convert H3D files into MNF files. This computational cost can be prohibitive for large models or systems with multiple degrees of freedom, limiting the efficiency of engineering analysis. This is especially true when frequent model modifications and optimizations are required. Long computational wait times can slow the overall workflow and hinder engineers' productivity.

[0026] In order to solve the above technical problems, according to an embodiment of the present application, an embodiment of a method for generating a wireframe flexible body MNF file is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0027] In this embodiment, a method for generating a wireframe flexible body MNF file is provided. Figure 1 A flowchart of a method for generating a wireframe flexible body MNF file provided in an embodiment of the present application is shown in FIG. Figure 1 As shown, the process includes the following steps: Step S1, loading the component geometry model to be analyzed, and meshing the component geometry model to obtain mesh units.

[0028] Specifically, the component geometry model is a three-dimensional representation of the component, usually generated by drawing software, and contains the shape, size and topological information of the component. In the finite element analysis software, the component geometry model is loaded through the file import function. The software reads the geometric information of the component geometry model (such as vertices, edges, faces, etc.) and displays it in the working environment. The component geometry model is meshed to obtain discretized mesh units, which can be tetrahedrons, hexahedrons, shell units, beam units, etc. The type of mesh unit selected depends on the geometric characteristics of the model and the analysis requirements.

[0029] In step S3, based on the geometric features of the component geometric model, key nodes related to modal analysis are selected from the mesh elements.

[0030] Specifically, it is necessary to conduct a detailed analysis of the component geometry model to identify characteristic points with important geometric significance, such as connection points, support points, free end points, and geometric characteristic points (such as vertices, edge midpoints, center points of faces, etc.). These characteristic points have a significant impact on the dynamic characteristics of the structure in modal analysis. Next, find the nodes corresponding to these characteristic points in the mesh units obtained by meshing and mark them as key nodes. Finally, according to the specific needs of the modal analysis, these marked nodes are further screened to ensure that the selected nodes can accurately reflect the dynamic behavior of the structure, thereby improving the accuracy and efficiency of the modal analysis. This process not only ensures the accuracy of the modal analysis, but also optimizes the use of computing resources by reducing unnecessary computing nodes.

[0031] Step S5: Use virtual connection units to connect key nodes until a complete wireframe structure is formed.

[0032] In one embodiment, the virtual connection unit adopts a Plotel unit; the key nodes are connected using the virtual connection unit until a complete wireframe structure is formed, including: the key nodes are connected using the Plotel unit until a complete wireframe structure is formed; wherein each Plotel unit represents a virtual connection between two key nodes.

[0033] Specifically, in the process of generating a wireframe structure, virtual connection units (such as Plotel units) are used to connect key nodes. The Plotel unit is a special finite element unit that simplifies the geometric structure of the model by defining virtual connections between nodes without participating in actual physical calculations. By using Plotel units to connect key nodes, a complete wireframe structure can be gradually constructed. This structure can represent the geometric features and dynamic characteristics of complex components in a more concise and efficient way. Each Plotel unit represents a virtual connection between two key nodes. This connection method not only reduces the complexity of the model, but also significantly improves the computational efficiency, while retaining the main dynamic behavior of the structure, providing a basis for subsequent modal analysis and multi-body dynamics simulation.

[0034] Step S7: Perform modal analysis on the wireframe structure and output the analysis results as a wireframe flexible body MNF file.

[0035] Specifically, modal analysis of wireframe structures is a key step in extracting their dynamic characteristics (such as modal frequencies and modal vibration shapes). Modal analysis provides necessary information for subsequent multi-body dynamics simulation by calculating the vibration behavior of the structure under different modes. After completing the modal analysis, the analysis results are exported as a wireframe flexible body MNF file, which is a neutral file format that can be directly read and used by a variety of multi-body dynamics simulation software (such as Adams). The MNF file contains key information such as modal frequencies, modal vibration shapes, and node coordinates, which enable the flexible body to accurately represent its dynamic behavior in multi-body dynamics simulation. In this way, modal analysis not only provides a quantitative description of the dynamic characteristics of complex structures, but also ensures that these characteristics can be effectively utilized in different simulation environments through the export of MNF files.

[0036] This embodiment provides a method for generating a wireframe flexible body MNF file. By loading the component geometry model and performing meshing, the component geometry is converted into a discrete mesh suitable for modal analysis, providing a basis for subsequent calculations. By selecting key nodes related to modal analysis and processing only important parts, unnecessary nodes and elements are avoided, thereby reducing the amount of calculation and saving calculation time. At the same time, the key nodes are connected through virtual connection units to form a wireframe structure. Compared with the traditional full three-dimensional structure, the number of elements and nodes is reduced, making the generated MNF file smaller. The modal analysis results are output as a streamlined wireframe flexible body MNF file, which further optimizes the file structure and reduces redundant data. Overall, it not only reduces the calculation time and file size, but also simplifies the operation complexity and improves the overall analysis efficiency.

[0037] Figure 2The flowchart of step S3 provided in the embodiment of the present application may include the following steps: Step S31 : marking nodes corresponding to mesh units according to geometric features of the component geometric model.

[0038] Specifically, pick up the geometric features of the component geometry model, including connection points connected to other parts, support points that are supported or constrained, free end points that are subject to load or motion, and geometric feature points such as vertices, edge midpoints, and center points of faces. Specifically, in the Hypermesh menu bar, select Analysis>Entity Sets. Name the node set, for example, marked_nodes. Select No Card Image to indicate that no specific card format or attribute is attached. Select No-Ordered to indicate that the elements in the set have no specific order. Select all the nodes that need to be marked, and then click Create to complete the creation of the node set. In this way, you can mark the marked nodes corresponding to the mesh units to ensure that all important geometric feature points are marked to avoid omissions.

[0039] Step S33 : Screening the marked nodes according to the analysis type of the modal analysis to obtain key nodes related to the modal analysis.

[0040] Specifically, the purpose of modal analysis is to calculate the modal frequencies and modal vibration shapes of the component structure. Different modal analysis types may require attention to different nodes. For example: global modal analysis needs to focus on the key nodes of the entire component structure. Local modal analysis needs to focus on the key nodes of a specific area. Constrained modal analysis needs to focus on the key nodes that are constrained. Therefore, the marked nodes can be filtered according to the type of modal analysis. In Hypermesh, use node selection tools (such as Mark or Select) to filter key nodes.

[0041] This embodiment can improve modeling accuracy by marking key nodes according to the geometric characteristics of the parts, ensuring that no important parts are missed in subsequent analysis. This not only optimizes the accuracy of finite element analysis, but also effectively reduces unnecessary errors. By screening out key nodes related to modal analysis, the amount of calculation can be greatly reduced, the analysis efficiency can be improved, and the accuracy of the results can be improved. The screened nodes help to focus on the most critical parts of the structure, such as stress concentration points or support points, thereby improving the accuracy of local analysis and reducing unnecessary computational burdens.

[0042] Figure 3 The flowchart provided in the embodiment of the present application before forming a complete wireframe structure may include the following steps: Step S41 , receiving analysis parameters for defining a component geometric model; wherein the parameters include unit type, material properties, and boundary conditions.

[0043] Specifically, before performing modal analysis, it is necessary to define the analysis parameters of the component geometry model, which include element type, material properties, and boundary conditions. These parameters determine the behavior and response of the component geometry model. Element types include tetrahedral elements, hexahedral elements, shell elements, and beam elements. Material properties include density, elastic modulus, Poisson's ratio, etc. These parameters define the physical properties of the material. Boundary conditions define the constraint state of the component geometry model in the analysis, such as fixed support points, free ends, load application points, etc. These analysis parameters are controlled by the user by selecting Analysis>Control Cards in the Hypermesh menu bar. The purpose is to enter the control card setting interface, which is used to define and manage the analysis parameters of the component geometry model. In the dialog box that pops up, select the MODEL control card. The MODEL control card is used to define the basic settings of the component geometry model, including element type, material properties, boundary conditions, etc.

[0044] Step S43: receiving the selected Plotel option so as to use the Plotel unit when performing modal analysis.

[0045] Specifically, the Plotel unit is a special virtual connection unit that is used to define the connection relationship between nodes without participating in actual physical calculations. In modal analysis, the Plotel unit is used to generate a wireframe flexible body model, which significantly reduces the amount of calculation while retaining the dynamic characteristics of the structure. The Plotel unit defines the geometric structure of the wireframe flexible body by virtually connecting key nodes. Specifically, in Hypermesh, the user controls the card through Analysis>Control Cards>MODEL and selects the Plotel option in Elset Options to explicitly tell the solver to use the Plotel unit in modal analysis to generate a wireframe flexible body model.

[0046] Step S45 , receiving the selected NORIGID option so that the Plotel element is used as a flexible element when performing modal analysis.

[0047] Specifically, the NORIGID option is used to define the behavior of Plotel elements, ensuring that they are treated as flexible elements rather than rigid elements in modal analyses. Flexible elements can deform, thereby preserving the dynamic properties of the structure. Specifically, in Hypermesh, users can explicitly tell the solver to treat Plotel elements as flexible elements by selecting the NORIGID option in the Rigidset Options section of the Analysis>Control Cards>MODEL control card.

[0048] This embodiment provides an accurate description and analysis basis for the component geometry model by receiving and defining analysis parameters (such as unit type, material properties and boundary conditions). These parameters enable modal analysis to truly reflect the dynamic response of the component under vibration conditions. Then, the Plotel unit is introduced as a virtual unit to simplify the calculation process while retaining the overall dynamic characteristics of the structure, significantly improving the calculation efficiency. Finally, the NORIGID option ensures that the Plotel unit participates in the analysis as a flexible unit rather than a rigid unit, making the modal analysis results more accurate, especially when dealing with the dynamic behavior of complex structures, and being able to better capture the vibration characteristics.

[0049] Figure 4 The flow chart for performing modal analysis on a wireframe structure provided in an embodiment of the present application may include the following steps: Step S71: construct a stiffness matrix based on the material properties and shape functions of the mesh elements.

[0050] Specifically, the material properties of the grid unit include elastic modulus E, Poisson's ratio ν, density ρ, etc. The stiffness matrix reflects the elastic properties of the structure. The unit shape function is a function that describes the displacement field inside the grid unit. For different unit types (such as linear units, quadratic units, etc.), the form of the shape function is different. For the embodiment of this application, a linear tetrahedron unit is used, and its unit shape function N i (ξ,η,ζ)=a i +b i ξ+c i η+d i ζ, where ξ, η, ζ are the local coordinates of the grid cell, used to describe the position of the point inside the cell; a i , b i , c i , d iis a coefficient related to the position of the unit node. The unit node is the vertex of the mesh unit, which defines the geometric shape and position of the mesh unit. For a tetrahedral unit, there are 4 nodes, and each node has a local coordinate value. For example, for a tetrahedral unit, the local coordinate values ​​of its 4 nodes can be defined as: node 1: (ξ1,η1,ζ1) = (0,0,0), node 2: (ξ2,η2,ζ2) = (1,0,0), node 3: (ξ3,η3,ζ3) = (0,1,0), node 4: (ξ4,η4,ζ4) = (0,0,1). The coefficient a of the shape function i , b i , c i , d i It is calculated based on the local coordinate values ​​of the unit nodes. For a tetrahedral unit, the coefficient of its shape function can be calculated by the following formula: i =1-b i -c i -d i ; b i =ξ i / V;c i =η i / V;d i =ζ i / V; where V is the volume of the tetrahedral element.

[0051] Local stiffness matrix K (e) By integrating the transpose of the strain-displacement matrix, the elastic matrix D of the material and the strain-displacement matrix, we get: Among them, V (e) is the unit volume of the grid unit; D is the elastic matrix of the material, which is related to the elastic modulus E and Poisson's ratio ν of the material; B is the strain-displacement matrix, which is determined by the shape function N i The derivative of .

[0052] The local stiffness matrix K of each element is calculated based on the material properties and the element shape function. (e) , then, the local stiffness matrices of all mesh elements are assembled into the global stiffness matrix K: Among them, N elem is the total number of grid cells.

[0053] Step S73: construct a mass matrix based on the material properties and unit volume of the grid unit.

[0054] Specifically, the mass matrix describes the inertial properties inside the unit and is closely related to the material density and the geometric volume of the unit. (e) By integrating the product of the shape function and the material density we get: Where ρ is the density in the material properties, N is the unit shape function, V (e) is the unit volume of the grid cell.

[0055] The local mass matrix M of all elements (e) Assemble into the global mass matrix M: Step S75 , adjusting the stiffness matrix and the mass matrix by using the boundary conditions in the component geometric model to obtain the target stiffness matrix and the target mass matrix.

[0056] Specifically, in finite element analysis, by applying boundary conditions to the component geometry model, the stiffness matrix K and mass matrix M can be adjusted to obtain the target stiffness matrix K that meets the actual constraint conditions. target and the target mass matrix M target . Boundary conditions define the constraint state of the structure in actual use. For example, fixed-end constraints will limit the displacement and rotational degrees of freedom of certain nodes. During the adjustment process, the degrees of freedom corresponding to the fixed-end nodes will be removed from the stiffness matrix and mass matrix, or zero-displacement constraints will be imposed to ensure that these degrees of freedom will not affect the vibration characteristics of the structure in subsequent modal analysis. After such adjustments, the target matrix obtained can more accurately reflect the dynamic characteristics of the structure under actual constraint conditions, thereby providing reliable input for modal analysis and accurately predicting the natural frequency and modal vibration shape of the structure.

[0057] Step S77: construct an eigenvalue equation based on the target stiffness matrix and the target mass matrix, and solve the eigenvalue equation to obtain analysis results including modal frequencies and modal vibration shapes.

[0058] Specifically, the eigenvalue equation is: (K-λM)Φ=0, where λ is the eigenvalue, which is proportional to the square of the modal frequency; Φ is the eigenvector, i.e., the modal vibration shape. The solver solves the above eigenvalue using numerical methods (such as the Lanczos method, subspace iteration method, etc.), and the calculated eigenvalue λ i Corresponding to the square of the modal frequency of the structure, that is: ω i 2 =λ i , where ω i is the i-th order modal frequency. The eigenvector Φ i Corresponding to the i-th mode shape.

[0059] This embodiment constructs a stiffness matrix using the material properties and shape functions of the mesh elements to ensure that the stiffness of the structure is consistent with the actual situation. Then, combining the material properties and volume, a mass matrix is ​​constructed to simulate the mass distribution and inertial characteristics of the structure. On this basis, the stiffness matrix and mass matrix are modified by adjusting the boundary conditions to ensure that the calculation results are consistent with the actual constraints. Finally, the eigenvalue equation is solved to obtain the modal frequencies and modal vibration shapes. This ensures that the subsequently generated MNF file only contains the necessary dynamic characteristics, avoiding redundant data and thus reducing the file size.

[0060] It should be noted here that before performing modal analysis, it is necessary to establish a Set, that is, to establish a wireframe model. Specifically, in Hypermesh, select Analysis>Entity Sets. Name the unit set to be created, such as plotel. Select No Card Image to indicate that no specific card format or attribute is attached. Select No-Ordered for Set type, which means that the elements in the set have no specific order. Select all 1D mesh units (such as beam units or rod units), click Create, complete the creation of the unit set, save and export the front_subframe_adm_e.fem file, and exporting the .fem file is the key step in finally using the solver to perform modal analysis on the wireframe structure in a format that can be read by the solver.

[0061] The OptiStruct solver is used. Import the previously generated wireframe structure (e.g., a .fem file) into the OptiStruct solver. Within the OptiStruct solver, set the modal analysis parameters, such as the modal order and frequency range. Start the solver and perform the modal analysis. The solver will calculate the modal frequencies and mode shapes of the structure. If errors are reported due to poor quality of individual mesh elements, select the CHECKEL NO option to ignore these errors, as they have little impact on the overall modal analysis.

[0062] In the OptiStruct solver, set the output file format to MNF, ensuring that the output file contains key information such as modal frequencies, mode shapes, and node coordinates. After the OptiStruct solver completes the modal analysis, it exports the modal information as a wireframe MNF file. This wireframe MNF file contains all the key information from the modal analysis, ensuring accurate simulation of the dynamic behavior of the flexible body in multibody dynamics simulations.

[0063] Figure 5 The flowchart of step S75 provided in the embodiment of the present application may include the following steps: Step S751: extract the fixed end nodes in the boundary conditions.

[0064] Specifically, in a finite element model, each node has multiple degrees of freedom (such as displacement and rotation in the x, y, and z directions), and boundary conditions simulate the constraints that the structure is subject to in actual use. For example, fixed-end node constraints simulate the connection of the structure to the ground or other fixed objects. The degrees of freedom of these nodes are constrained and cannot move freely. Typically, fixed-end nodes are represented in the finite element model as having zero displacement in certain directions. This is called a boundary condition.

[0065] Step S753: For each fixed end node, delete the row and column corresponding to each fixed end node in the stiffness matrix to obtain the target stiffness matrix.

[0066] Specifically, for fixed end nodes, their degrees of freedom (such as displacement and rotation) will affect the stiffness of the entire structure. For fixed end nodes, their degrees of freedom are constrained, that is, the displacement of these nodes is zero. Therefore, the rows and columns related to these fixed end nodes in the stiffness matrix need to be deleted to ensure that these nodes do not affect the vibration characteristics of the structure during the calculation. For example, if the x-direction of the fixed end node is constrained, then the rows and columns related to the x-direction of the node in the stiffness matrix K need to be deleted. Deleting these rows and columns is equivalent to removing these degrees of freedom from the vibration mode of the entire structure, so that the stiffness matrix no longer considers the influence of these fixed end nodes.

[0067] Step S755: For each fixed end node, delete the row and column corresponding to each fixed end node in the mass matrix to obtain a target mass matrix.

[0068] Specifically, similar to the stiffness matrix, the degrees of freedom of the fixed end nodes should be removed from the mass matrix. For fixed end nodes, their degrees of freedom are constrained, meaning their mass or inertia is fixed in a specific direction. To accurately calculate modal properties, the rows and columns associated with the fixed end nodes in the mass matrix need to be removed. This prevents the fixed end nodes from interfering with the modal analysis results.

[0069] By deleting the rows and columns corresponding to the fixed end nodes, the target stiffness matrix K is obtained. target and the target mass matrix M target These matrices reflect the dynamic characteristics of the structure under actual constraint conditions, that is, the influence of the fixed end nodes being constrained. Using these matrices, the natural frequencies and mode shapes of the structure can be accurately calculated, thereby obtaining more accurate dynamic response analysis results.

[0070] This embodiment extracts the fixed-end nodes from the boundary conditions and deletes the rows and columns corresponding to these fixed-end nodes from the stiffness matrix. Because these rows and columns do not affect the structural deformation, deletion significantly reduces the computational effort, thereby improving efficiency. Similarly, rows and columns associated with fixed-end nodes should be deleted from the mass matrix to avoid unnecessary mass contributions. This reduces the size of the matrix, conserves computing resources, reduces memory usage, and speeds up modal analysis. Ultimately, the resulting MNF file is smaller, easier to store and transfer, and simpler to operate.

[0071] Figure 6 The flowchart provided in the embodiment of the present application after obtaining the grid unit may include the following steps: Step S21, detecting the material density unit used in the component geometric model and comparing it with the material density unit preset in the simulation software.

[0072] Step S23 : If the material density unit used is inconsistent with the preset material density unit, the material density unit used is corrected to make the material density unit used consistent with the preset material density unit.

[0073] The material density unit must be consistent with the preset unit of the simulation software (such as Adams), otherwise the simulation software may not be able to correctly read the modal information. Specifically, in Hypermesh, check the material density unit defined in the component geometry model. Usually, the material density unit can be kilograms per cubic meter (kg / m 3 ) or grams per cubic centimeter (g / cm 3 ) etc. Multibody dynamics simulation software such as Adams usually uses the International System of Units (SI), where the unit of material density is kilograms per cubic meter (kg / m 3 Compare the material density units used in the Material Density Units dialog box with the Adams preset material density units to ensure they are consistent. If a discrepancy is detected, perform a unit conversion. In Hypermesh, access the material properties interface and find the material density definition. Modify the material density value to match the Adams preset units. Save the modified material properties.

[0074] This embodiment ensures the consistency of material density units by detecting the material density units used in the component geometry model and comparing them with the preset material density units in the simulation software. This avoids calculation errors caused by inconsistent units and improves the accuracy and reliability of simulation analysis. If inconsistent material density units are found, corrections are made to align them with the preset material density units. This not only eliminates errors caused by inconsistent units but also ensures the accuracy of simulation results.

[0075] Accordingly, please refer to Figure 7 A block diagram of a wireframe flexible body MNF file generation device provided in an embodiment of the present application, the device comprising: A meshing unit 101 is used to load a component geometry model to be analyzed and mesh the component geometry model to obtain mesh units; A selection node element 103 is used to select key nodes related to modal analysis from mesh elements based on geometric features of the component geometric model; A wireframe forming unit 105 is used to connect key nodes using virtual connection units until a complete wireframe structure is formed; The modal analysis unit 107 is used to perform modal analysis on the wireframe structure and output the analysis results as a wireframe flexible body MNF file.

[0076] In some optional implementations, selecting the node unit 103 includes: According to the geometric features of the component geometry model, mark the nodes corresponding to the grid elements; According to the analysis type of modal analysis, the marked nodes are screened to obtain the key nodes related to the modal analysis.

[0077] In some optional implementations, the virtual connection unit uses a Plotel unit; the wireframe forming unit 105 includes: using the Plotel unit to connect key nodes until a complete wireframe structure is formed; wherein each Plotel unit represents a virtual connection between two key nodes.

[0078] In some optional embodiments, before forming a complete wireframe structure, the apparatus further comprises: receiving analysis parameters for defining a component geometry model; wherein the parameters include element type, material properties, and boundary conditions; and receiving a selected Plotel option to use Plotel elements when performing a modal analysis; Accepts the selection of the NORIGID option to use Plotel elements as flexible elements when performing modal analysis.

[0079] In some optional implementations, the modal analysis unit 107 includes: Construct a stiffness matrix based on the material properties and element shape functions of the mesh elements; Construct a mass matrix based on the material properties and unit volume of the grid cells; Adjust the stiffness matrix and mass matrix through the boundary conditions in the component geometry model to obtain the target stiffness matrix and target mass matrix; Based on the target stiffness matrix and the target mass matrix, the eigenvalue equation is constructed and solved to obtain the analysis results including the modal frequency and modal vibration shape.

[0080] In some optional implementations, adjusting the stiffness matrix and the mass matrix by using boundary conditions in the component geometric model to obtain a target stiffness matrix and a target mass matrix includes: Extract fixed end nodes in boundary conditions; For each fixed end node, delete the corresponding row and column of each fixed end node in the stiffness matrix to obtain the target stiffness matrix; for each fixed end node, delete the corresponding row and column of each fixed end node in the mass matrix to obtain the target mass matrix.

[0081] In some optional embodiments, after obtaining the grid unit, the apparatus further includes: Check the material density units used in the component geometry model and compare them with the material density units preset in the simulation software; if the material density units used are inconsistent with the preset material density units, correct the material density units used to make them consistent with the preset material density units.

[0082] The further functional description of each of the above modules and units is the same as that of the above corresponding embodiments and will not be repeated here.

[0083] In this embodiment, a wireframe flexible body MNF file generation device is presented in the form of a functional unit, where the unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and memory that executes one or more software or fixed programs, and / or other devices that can provide the above functions.

[0084] See also Figure 8 , Figure 8 A schematic diagram of the structure of a computer device provided in an embodiment of the present application is shown in FIG. Figure 8As shown, the computer device includes: one or more processors 10, memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. Various components utilize different buses to communicate with each other and can be installed on a common mainboard or installed in other ways as needed. The processor can process the instructions executed in the computer device, including instructions stored in the memory or on the memory to display the graphical information of the GUI on an external input / output device (such as, a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Equally, multiple computer devices can be connected, and each device provides part of the necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Figure 8 A processor 10 is taken as an example.

[0085] The processor 10 may be a central processing unit, a network processor, or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit, a programmable logic device, or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic, or any combination thereof.

[0086] The memory 20 stores instructions that can be executed by at least one processor 10, so that the at least one processor 10 executes the method shown in the above embodiment.

[0087] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and application programs required for at least one function; the data storage area may store data created based on the use of the computer device, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely located relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0088] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0089] The computer device further includes a communication interface 30 for the computer device to communicate with other devices or a communication network.

[0090] The embodiments of the present application also provide a computer-readable storage medium. The above-mentioned method according to the embodiment of the present application can be implemented in hardware, firmware, or implemented as a computer code that can be recorded in a storage medium, or implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and downloaded through a network and will be stored in a local storage medium, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state drive, etc.; further, the storage medium can also include a combination of the above-mentioned types of memory. It can be understood that a computer, a processor, a microprocessor controller or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor or hardware, the method shown in the above embodiment is implemented.

[0091] The methods, devices, or units described in the above embodiments may be implemented by a computer chip or entity, or by a product having certain functions. A typical implementation device is a computer. Specifically, the computer may be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smartphone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0092] For the convenience of description, the above devices are described as being divided into various units according to their functions. Of course, when implementing this application, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0093] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods or devices. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0094] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices, and apparatus according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0095] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0096] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0097] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0098] The various embodiments in this specification are described in a progressive manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences from other embodiments. In particular, the device embodiments are generally similar to the method embodiments, so the description is relatively simple. For relevant parts, refer to the description of the method embodiments.

[0099] The foregoing is merely an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

[0100] Although the embodiments of the present application have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present application, and such modifications and variations shall fall within the scope defined by the appended claims.

Claims

1. A method for generating a wireframe flexible body MNF file, characterized in that: The method comprises: Loading a component geometry model to be analyzed, and meshing the component geometry model to obtain mesh units; Selecting key nodes related to modal analysis from the mesh elements based on geometric features of the component geometric model; Connecting the key nodes using virtual connection units until a complete wireframe structure is formed; Performing modal analysis on the wireframe structure, and outputting the analysis results as the wireframe flexible body MNF file.

2. The method according to claim 1, characterized in that The step of selecting key nodes related to modal analysis from the mesh elements based on the geometric features of the component geometric model includes: Marking nodes corresponding to the grid units according to the geometric features of the component geometric model; According to the analysis type of the modal analysis, the marked nodes are screened to obtain key nodes related to the modal analysis.

3. The method according to claim 1, characterized in that The virtual connection unit adopts a Plotel unit; the key nodes are connected by using the virtual connection unit until a complete wireframe structure is formed, including: The key nodes are connected using the Plotel units until a complete wireframe structure is formed; wherein each Plotel unit represents a virtual connection between two key nodes.

4. The method according to claim 3, characterized in that Before forming the complete wireframe structure, the method further includes: receiving analysis parameters for defining the component geometry model; wherein the parameters include element type, material properties, and boundary conditions; Accept the selected Plotel option so that Plotel elements are used when performing modal analysis; Receive the selection of the NORIGID option so that the Plotel element is used as a flexible element when performing a modal analysis.

5. The method according to claim 1, wherein The performing modal analysis on the wireframe structure includes: constructing a stiffness matrix based on the material properties and unit shape functions of the grid units; constructing a mass matrix based on the material properties and unit volume of the grid unit; Adjusting the stiffness matrix and the mass matrix according to the boundary conditions in the component geometric model to obtain a target stiffness matrix and a target mass matrix; Based on the target stiffness matrix and the target mass matrix, an eigenvalue equation is constructed, and the eigenvalue equation is solved to obtain analysis results including modal frequencies and modal vibration shapes.

6. The method according to claim 5, characterized in that The adjusting the stiffness matrix and the mass matrix by the boundary conditions in the component geometric model to obtain the target stiffness matrix and the target mass matrix includes: extracting the fixed end nodes in the boundary conditions; For each fixed end node, delete the row and column corresponding to each fixed end node in the stiffness matrix to obtain the target stiffness matrix; For each fixed end node, the row and column corresponding to each fixed end node in the mass matrix are deleted to obtain the target mass matrix.

7. The method according to claim 1, characterized in that After obtaining the grid unit, the method further includes: Detecting the material density units used in the component geometry model and comparing them with the material density units preset in the simulation software; If the material density unit used is inconsistent with the preset material density unit, the material density unit used is corrected to make the material density unit used consistent with the preset material density unit.

8. A wireframe flexible body MNF file generation device, characterized in that: The device comprises: A meshing unit, used for loading a geometric model of a component to be analyzed and meshing the geometric model of the component to obtain mesh units; Selecting node elements, for selecting key nodes related to modal analysis from the mesh elements based on geometric features of the component geometric model; a wireframe forming unit, configured to connect the key nodes using virtual connection units until a complete wireframe structure is formed; The modal analysis unit is used to perform modal analysis on the wireframe structure and output the analysis result as the wireframe flexible body MNF file.

9. A computer device, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the wireframe flexible body MNF file generation method according to any one of claims 1 to 7 by executing the computer instructions.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the method for generating a wireframe flexible body MNF file according to any one of claims 1 to 7.

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