Structure design method based on skeleton attribute extraction technology

Abstract

The present invention relates to a structural design method based on skeleton attribute extraction technology, comprising establishing a skeleton model: characterized by key physical and geometric information of key nodes of the structure, establishing a storage model for these key information, and converting the data information stored in the model into skeleton attribute information; obtaining skeleton model information: performing finite element division and topological optimization on the original structure of the design target to obtain a topologically optimized model. The present invention combines the development of finite element technology, utilizes the relevant characteristics of finite element analysis, introduces blocks and slices, and divides the entire solid structure into several parts for analysis. The grid nodes closest to the shape center of each part are selected as key nodes, connected in sequence, and important data in the finite element analysis results are extracted to form a structural skeleton and make it easier to analyze the physical properties of each node on the skeleton. After the physical properties are extracted and analyzed, a theoretical basis can be provided for subsequent analysis based on the skeleton.

Description

Technical Field

[0001] The present invention relates to an engineering structure design technology, and in particular to a method for extracting a skeleton model of a structure and analyzing key performance attributes of the structure for use in structure redesign based on topology optimization. Background Art

[0002] Structural topology optimization can provide designers with a conceptual design in the initial stages of engineering structure design, enabling them to adopt the optimal layout and topology for the structure, achieving better optimization results than size optimization and shape optimization. The goal of structural topology optimization is to find the optimal topology to maximize structural performance while satisfying various constraints, such as a certain amount of material, volume constraints, and the maximum and minimum dimensions of the structure. Compared to size and shape optimization, topology optimization offers greater freedom, allowing designers to create completely novel and efficient conceptual designs for structures. Therefore, topology optimization has become a key consideration in current research on structural optimization design.

[0003] However, the structural geometry and physical property information corresponding to the structure obtained by topology optimization are relatively complex. Current design technology lacks methods to effectively extract, store and utilize topological structure information for structural redesign.

[0004] Therefore, the current engineering method of topology design is to reconstruct the geometric shape based on the empirical analysis of the topological structure by engineers, rather than to reconstruct the performance of key features based on the physical and performance properties of the post-topological structure.

[0005] Therefore, it is necessary to propose a skeleton model extraction technology and its corresponding structural design method that can effectively extract and store the topological information, shape characteristics, and performance characteristics of the structure after topological optimization design (stress and strain information under various analysis conditions during the topological design process; vibration frequency and mode shape information under excitation conditions, etc.). In other words, the skeleton model not only stores the geometric and spatial morphological characteristics that can effectively describe the topological structure, but more importantly, it can also provide the performance characteristics of the structure. Summary of the Invention

[0006] The present invention proposes a structural design method based on skeleton attribute extraction technology, which mainly considers extracting the skeleton of the model after topology optimization is completed to obtain the parameters required to be extracted and the storage structure of the skeleton model, and then extracts and stores data of the topological model according to the requirements of the skeleton model. Through data analysis of the skeleton model, the design and performance conditions that need to be met in accordance with the performance requirements are given, providing scientific guidance and data guarantee for completing the industrial / engineering redesign of the topological structure.

[0007] The technical solution of the present invention is: a structural design method based on skeleton attribute extraction technology, which specifically includes the following steps:

[0008] 1) Establish a skeleton model: Use the key physical and geometric information of the key nodes of the structure to represent this key information, establish a storage model for this key information, and convert the data information stored in the model into skeleton attribute information;

[0009] 2) Obtain skeleton model information: Perform finite element partitioning and topology optimization on the original structure of the design target to obtain a topology-optimized model;

[0010] 3) The topology model obtained by topology optimization is divided into geometric blocks and sliced. After slicing, the blocks are redefined and the model is divided into several parts for easy analysis.

[0011] 4) Read the numbers of the finite element mesh nodes contained in each slice, and find the mesh node closest to the center point of each block as the key node;

[0012] 5) Find the constraint points formed by the connection between the structure and the outside world as key nodes;

[0013] 6) Extract key physical and performance information such as key node positions, stress and strain, force conduction, amplitudes of each order, and slice quality;

[0014] 7) Starting from the constraint points, connect the key nodes according to the slice information to determine the spatial geometric position and shape of the skeleton;

[0015] 8) Analyze the skeleton, propose the coordinate values and deformation of each node, and derive the static stiffness matrix of each node by writing APDL code to determine the performance conditions that need to be met to meet the performance requirements.

[0016] Furthermore, in step 3), for the topological structure model after topology optimization, each fixed constraint node p is recorded separately. i The coordinates of the fixed constraint node are the minimum deformation value; the maximum deformation value is read out to determine the coordinates of the maximum deformation point; according to the size of the deformation, the structure is evenly divided into multiple sub-areas, recorded as block B i ,i=1,2,…,n;Starting from each fixed constraint node, take xoy plane, yoz plane and xoz plane as the first slice respectively; take the multiple of grid unit size λ as the step size, slice the model in x, y and z directions respectively, and record the slice as C j , if no branching is encountered during the slicing process, only the single connected region is taken.

[0017] Furthermore, in step 4), the distance dist between each finite element mesh node and the center point is calculated using the distance formula between two points, and the coordinates of the finite element mesh node corresponding to the minimum value d of dist are recorded as the key nodes in the block;

[0018] Further, the specific method steps of step 8) are:

[0019] (1) Analyze the original model using finite element analysis software, set the mesh size, and perform topological optimization on the model. The coordinate values and deformation values of each skeleton node after optimization are extracted and recorded using the finite element analysis software. Group the nodes according to the deformation size according to the definition of the block.

[0020] (2) Based on the slice definition and the above steps, define a new block after screening in the record file and record the coordinates of the corresponding direction of the key slice;

[0021] According to the recorded coordinate values, calculate the center point M of each block i The x, y, and z coordinates of the slice are represented by C, and i is related to the number of blocks.

[0022] Calculate the T of each node in the block k， The size of k depends on the number of nodes in the block and the center point M i The distance between them is calculated and arranged in ascending order. The minimum value of dist_k is recorded as d, and the coordinates corresponding to d are recorded as the coordinates of the key nodes.

[0023] (3) Arrange each node in the order of connection and draw each node using numerical processing software. The resulting point-line diagram is the skeleton of the structure.

[0024] The beneficial effects of the present invention are as follows: the present invention combines the development of finite element technology, utilizes the relevant characteristics of finite element analysis, introduces blocks and slices, and divides the entire solid structure into several parts for analysis. The grid nodes closest to the shape center of each part are selected as key nodes, connected in sequence, and important data from the finite element analysis results are extracted to form a structural skeleton. It is also easier to analyze the physical properties of each node on the skeleton. After the physical properties are extracted and analyzed, a theoretical basis can be provided for subsequent analysis based on the skeleton (such as realizing model reconstruction, etc.). BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the front of the model after topology optimization is completed;

[0026] Figure 2 This is a schematic diagram of the back of the model after topology optimization is completed;

[0027] Figure 3 A schematic diagram of the block;

[0028] Figure 4 is a schematic diagram of slicing along the z direction;

[0029] Figure 5 Schematic diagram of dividing new blocks during slicing;

[0030] Figure 6 This is a schematic diagram of the first branching situation encountered during the slicing process;

[0031] Figure 7 This is a schematic diagram of the second branching situation encountered during the slicing process;

[0032] Figure 8 This is a schematic diagram of the front view after superimposing the skeleton and the original model;

[0033] Figure 9 This is a schematic diagram of the back after superimposing the skeleton and the original model. DETAILED DESCRIPTION

[0034] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0035] The skeleton extraction method based on the topology optimized model of the present invention specifically includes the following steps:

[0036] 1. First, the skeleton of the model needs to be extracted. Here, the model of a three-dimensional L-shaped bracket after topology is used as an example. The specific steps of the extraction process are as follows:

[0037] 1.1 The model after topology optimization is as follows Figure 1 and Figure 2 As shown, each fixed constraint node p is recorded separately i The coordinates of the fixed constraint node are fixed at the minimum deformation value deformation_min.

[0038] 1.2 Read the maximum deformation value deformation_max and determine the coordinates of the maximum deformation point;

[0039] 1.3 According to the size of the deformation, the area between deformation_min and deformation_max is evenly divided into 14 sub-areas, recorded as block B i (i=1,2,…,14), such as Figure 3 As shown;

[0040] 1.4 Starting from each fixed constraint node, take the x0y plane, y0z plane and x0z plane as the first slice respectively;

[0041] 1.5 Take 5 times of the grid cell size λ as the step size, slice the model in the x, y, and z directions respectively, and record the slice as C j , only single-connected regions are taken during the slicing process (multiple-connected regions are considered only when branches are encountered), where the slices in the z direction are as follows Figure 4 As shown;

[0042] 1.6 Determine whether there is a situation where there is no node of a certain block in a certain slice, but some (or all) nodes of the block appear in the previous slice. If so, start from the previous slice, reduce the step size to λ and continue slicing until the same situation occurs again. At this time, record the coordinate value of the corresponding coordinate axis of the next slice (for example, if this situation occurs when slicing from the x0y plane, record the z-direction coordinate value of the slice) as the upper limit of the coordinate of the newly defined block in the direction of the axis, such as Figure 5 As shown;

[0043] 1.7 Determine whether there is a situation where some (or all) of a block node appears in a certain slice, but there is no such block node in the previous slice. If so, start from the previous slice, reduce the step size to λ, and continue slicing until the same situation occurs again. At this time, record the coordinate value of the coordinate axis corresponding to the previous slice as the lower limit of the coordinate of the newly defined block in the direction of the axis, such as Figure 5 As shown;

[0044] 1.8 Determine whether the projected area of a certain slice's corresponding plane changes significantly compared to the previous slice during the slicing process; or whether the area corresponding to a certain slice is a multiply connected area, while the previous slice is a normal single connected area. If so, it means that there is a branch in this part. Define the entire branch as a branch block. Similarly, after reducing the step size and obtaining the slice, record the coordinate value of the corresponding coordinate axis direction corresponding to the previous slice as the maximum or minimum coordinate value of the branch block in this direction, such as Figure 6 and Figure 7 As shown;

[0045] 1.9 determines whether the slice has reached the point of maximum deformation value. If so, go to 1.10; otherwise, go to 1.5 and continue iterating.

[0046] 1.10 Re-divide the model into blocks according to the recorded slices and define the new blocks as B i， At this time, the size of i depends on the number of blocks;

[0047] 1.11 From each constraint node p iSet out to find the next newly defined block;

[0048] 1.12 According to the coordinate values of the slices recorded, calculate the coordinate values of the center point of the new block by taking the average method, and record the center point as M i ;

[0049] 1.13 Let all grid nodes in the new block be T k , the value of k depends on the number of nodes in the block;

[0050] 1.14 Calculate the distance dist between each grid node and the center point using the distance formula between two points, and record the grid node coordinates corresponding to the minimum value d of dist as the key node in the block;

[0051] 1.15 Determine whether the maximum deformation value point has been reached. If so, go to 1.16. Otherwise, start from this block and continue iterating from 1.12 to the next closest block.

[0052] 1.16 Connect each node in sequence, and the resulting three-dimensional point-line diagram is part of the structural skeleton;

[0053] 1.17 Determine whether there are two recent blocks in the previous step. If so, it means there is a branch block. Go to 1.11 and start iterating again. If a branch is encountered in this iteration, select the branch as the next block;

[0054] 1.18 Determine whether the above steps have been performed for all fixed constraint nodes. If not, go to 1.11 to continue iterating;

[0055] 1.19 By removing duplicate nodes, we can obtain the complete skeleton of the structure.

[0056] 2. The following is a detailed description of the steps of the skeleton extraction process:

[0057] 2.1 Use Ansys Workbench software to analyze the original model, set the grid size to 1mm, and perform topology optimization on the model. Figure 1 and Figure 2 As shown;

[0058] 2.2 Use Ansys Workbench software to extract the coordinate values and deformation values of each skeleton node after optimization and record them in Excel;

[0059] 2.3 According to the definition of blocks, the nodes are grouped according to the deformation size;

[0060] 2.4 Based on the slice definition and the above steps, define new blocks after filtering in Excel and record the coordinates of the corresponding directions of the key slices;

[0061] 2.5 According to the recorded coordinate values, use the formula To calculate the center point M of each block i The x, y, and z coordinates of the slice are represented by C, and i is related to the number of blocks.

[0062] 2.6 According to Calculate the T of each node in the block k (The size of k depends on the number of nodes in the block) and the center point M i The distance between them is calculated and arranged in ascending order. The minimum value of dist_k is recorded as d, and the coordinates corresponding to d are recorded as the coordinates of the key nodes.

[0063] 2.7 Repeat the steps in 2.6 for each block and record all key nodes;

[0064] 2.8 Arrange each node in the order of connection and draw a node point-line diagram, which is the skeleton of the structure;

[0065] 2.9 Superimpose it with the original model and get Figure 8 and Figure 9 ;

[0066] 2.10 Write the APDL code, obtain the static stiffness matrix of each node by inputting the node number, and record the various physical properties, as shown in Table 1;

[0067] Table 1

[0068]

[0069] 2.11 In summary, the skeleton extraction of the structure and the subsequent partial analysis can be achieved through the steps described in the present invention.

[0070] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A structural design method based on skeleton attribute extraction technology, characterized by: The proposed skeleton contains not only the geometric information of the structure, but also the physical information of the skeleton. Based on the extraction and analysis of physical properties, it provides a theoretical basis for subsequent skeleton-based analysis. Specifically, it includes the following steps: 1) Establish a skeleton model: Use the key physical and geometric information of the key nodes of the structure to represent this key information, establish a storage model for this key information, and convert the data information stored in the model into skeleton attribute information; 2) Obtain skeleton model information: Perform finite element partitioning and topology optimization on the original structure of the design target to obtain a topology-optimized model; 3) The topology model obtained by topology optimization is divided into geometric blocks and sliced. After slicing, the blocks are redefined and the model is divided into several parts for easy analysis. 4) Read out the numbers of the finite element mesh nodes contained in each redefined block, and find the mesh node closest to the center point of each block as the key node; 5) Find the constraint points formed by the connection between the structure and the outside world as key nodes; 6) Extract key physical and performance information such as key node positions, stress and strain, force conduction, amplitudes of each order, and slice quality; 7) Starting from the constraint points, connect the key nodes according to the slice information to determine the spatial geometric position and shape of the skeleton; 8) Analyze the skeleton, propose the coordinate values and deformation of each node, calculate the static stiffness matrix of each node, and determine the performance conditions that need to be met to meet the performance requirements.

2. The structural design method based on skeleton attribute extraction technology according to claim 1, characterized in that: In step 3), for the topology structure model after topology optimization, record each fixed constraint node p i The coordinates of the fixed constraint node are the minimum deformation values; Read out the maximum deformation value and determine the coordinates of the maximum deformation point; According to the size of the deformation, the area between the minimum and maximum deformation values is evenly divided into multiple sub-areas, which are recorded as block B. i ,i=1,2,…,n;Starting from each fixed constraint node, take xoy plane, yoz plane and xoz plane as the first slice respectively; take the multiple of grid unit size λ as the step size, slice the model in x, y and z directions respectively, and record the slice as C j , if no branching is encountered during the slicing process, only the single connected region is taken.

3. The structural design method based on skeleton attribute extraction technology according to claim 1, characterized in that: In step 4), the distance between each finite element mesh node and the center point is calculated using the distance formula between two points, and the coordinates of the finite element mesh node corresponding to the minimum value of the distance are recorded, and the node is used as the key node in the block.

4. The structural design method based on skeleton attribute extraction technology according to claim 1, characterized in that: The specific method steps of step 8) are: (1) Analyze the original model using finite element analysis software, set the mesh size, and perform topological optimization on the model. The coordinate values and deformation values of each skeleton node after optimization are extracted and recorded using the finite element analysis software. Group the nodes according to the deformation size according to the definition of the block. (2) Based on the slice definition and the above steps, define a new block after screening in the record file and record the coordinates of the corresponding direction of the key slice; Calculate the coordinates of the center point of each block based on the recorded coordinate values; consider the distance between the number of nodes in the block and the center point, calculate each node in the block, and arrange them in ascending order. Record the minimum value of the distance between the number of nodes in the block and the center point as d, and record the coordinates corresponding to d as the coordinates of the key node; (3) Arrange each node in the order of connection and draw each node using numerical processing software. The resulting point-line diagram is the skeleton of the structure.

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