CN115471633A - Structure design method based on skeleton attribute extraction technology - Google Patents
Structure design method based on skeleton attribute extraction technology Download PDFInfo
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Abstract
The invention relates to a structural design method based on a skeleton attribute extraction technology, which comprises the following steps of establishing a skeleton model: the method comprises the steps of establishing a storage model of key information represented by key physical and geometric information of structural key nodes, and enabling data information stored by the model to be skeleton attribute information; obtaining skeleton model information: and carrying out finite element division and topological optimization on the original structure of the design target to obtain a model after topological optimization. The invention combines the development of finite element technology, utilizes the relevant characteristics of finite element analysis, introduces blocks and slices, and divides the whole solid structure into a plurality of parts for analysis. The mesh nodes closest to the center of the shape of each part are selected as key nodes and are connected in sequence, important data in the finite element analysis result are extracted, a structural framework is formed, physical properties of all the nodes on the framework can be analyzed more easily, and after the physical properties are extracted and analyzed, theoretical basis can be provided for subsequent analysis according to the framework.
Description
Technical Field
The invention relates to an engineering structure design technology, in particular to a method for carrying out skeleton model extraction and structure key performance attribute analysis of a structure for structure redesign based on topology optimization.
Background
The structural topology optimization can provide a conceptual design for designers at the initial stage of engineering structure design, so that the structure adopts an optimal scheme on layout and topology, and a better optimization effect can be achieved compared with size optimization and shape optimization. The goal of structural topology optimization is to find the best topology to maximize the performance of the structure while satisfying various constraints such as a certain amount of material, volume constraints, and the maximum and minimum dimensions in the structure, among others. Compared with size and shape optimization, topological optimization provides more freedom, allows designers to create completely novel and efficient conceptual designs for structures, and therefore becomes a key point to be considered when researching structural optimization design nowadays.
However, the geometric shape of the structure obtained by topology optimization and the physical attribute information corresponding to the structure are relatively complex, and a method for effectively extracting, storing and utilizing the topological structure information to redesign the structure is lacked in the current design technology.
Therefore, the current engineering method of topology design is based on the reconstruction of the geometric shape by the empirical analysis of the topological structure by the engineering personnel, and is not based on the performance reconstruction of the key features by the physical property and the performance property of the topological structure.
Therefore, it is necessary to provide a skeleton model extraction technique and a structure design method corresponding thereto, which can effectively extract and store topology information, shape characteristics, and performance characteristics (stress and strain information under various analysis conditions in the topology design process, vibration frequency and vibration mode information under the excitation condition, etc.) of the structure after the topology optimization design. That is, the skeleton model stores the geometric and spatial morphological characteristics capable of effectively describing the topological structure, and more importantly, the skeleton model can provide the performance characteristics of the structure.
Disclosure of Invention
The invention provides a structure design method based on a skeleton attribute extraction technology, which mainly considers the extraction of a skeleton of a model after topology optimization is completed so as to obtain parameters to be extracted and a storage structure of the skeleton model, extracts and stores data of the topology model according to the requirement of the skeleton model, provides design and performance conditions meeting performance requirements through data analysis of the skeleton model, and provides scientific guidance and data guarantee for industrial/engineering redesign of the topology structure.
The technical scheme of the invention is as follows: a structure design method based on a skeleton attribute extraction technology specifically comprises the following steps:
1) Establishing a skeleton model: the method comprises the steps of adopting key physics and geometric information represented by structural key nodes to establish a storage model of the key information, and enabling data information stored by the model to be skeleton attribute information;
2) Obtaining skeleton model information: carrying out finite element division and topological optimization on the original structure of the design target to obtain a model after topological optimization;
3) Partitioning and slicing a geometric structure of a topological structure model obtained by topological optimization, redefining partitioning after slicing is finished, and dividing the model into a plurality of parts to facilitate analysis;
4) Reading the number of the finite element grid node contained in each slice, and searching the grid node closest to the center point of the block in each block as a key node;
5) Searching a constraint point formed by connecting the structure with the outside as a key node;
6) Extracting key physical information and performance information of key node positions, stress strains, force conduction, amplitudes of all orders and slicing quality;
7) Starting from the constraint point, connecting key nodes according to slice information, and determining the spatial geometric position and form of the skeleton;
8) And analyzing the skeleton, providing coordinate values and deformation of each node, obtaining a static stiffness matrix of each node by writing APDL codes, and determining performance conditions meeting performance requirements.
Further, in step 3), for the topology structure model after the topology optimization is completed, each fixed constraint node p is respectively recorded i The deformation value at the fixed constraint node is the minimum deformation value; reading out the maximum deformation value, and determining the coordinate of the maximum deformation point; according to the size of the deformation, the structure is uniformly divided into a plurality of sub-regions, which are marked as blocks B i I =1,2, \ 8230;, n; starting from each fixed constraint node, respectively taking an xoy plane, a yoz plane and an xoz plane as first slices; respectively slicing the model in the three directions of x, y and z by taking the multiple of the size lambda of the grid unit as a step length, and recording the slices as C j And if no branch condition is encountered in the slicing process, only taking a single connected region.
Further, in step 4), calculating a distance dist between each finite element grid node and the central point by using a distance formula between the two points, and recording a finite element grid node coordinate corresponding to the minimum value d of the dist as a key node in the block;
further, the specific method of step 8) comprises the following steps:
(1) Analyzing the original model by using finite element analysis software, setting the size of a grid, carrying out topology optimization on the model, extracting the coordinate values and the deformation values of each optimized framework node by using the finite element analysis software, and recording; according to the definition of the block, the nodes are grouped according to the deformation size;
(2) According to the slice definition and the steps, a new block is defined after screening in the record file, and the coordinates of the key slice in the corresponding direction are recorded;
according to the recorded coordinate values, calculating the central point M of each block i Wherein C represents the corresponding coordinate value of the slice, and i is related to the number of blocks;
calculate each node T in the block k， The size of k depends on the number of nodes within the blockAnd a center point M i The distances between the nodes are arranged in ascending order, the minimum value of dist _ k is recorded as d, and the coordinate corresponding to d is recorded as the coordinate of the key node;
(3) And arranging each node according to the connection sequence, drawing each node by using numerical processing software, and obtaining a point line graph which is the skeleton of the structure.
The invention has the beneficial effects that: the invention combines the development of finite element technology, utilizes the relevant characteristics of finite element analysis, introduces blocks and slices, and divides the whole solid structure into a plurality of parts for analysis. The mesh nodes closest to the center of the shape of each part are selected as key nodes and are connected in sequence, important data in the finite element analysis result are extracted, a structural framework is formed, physical properties of each node on the framework can be analyzed more easily, and after the physical properties are extracted and analyzed, theoretical basis can be provided for subsequent analysis (such as reconstruction of an implementation model) based on the framework.
Drawings
FIG. 1 is a schematic diagram of a front side of a model after topology optimization is complete;
FIG. 2 is a schematic diagram of the back of the model after topology optimization is complete;
FIG. 3 is a block diagram;
FIG. 4 is a schematic view of a slice taken along the z-direction;
FIG. 5 is a diagram illustrating the division of new blocks during slicing;
FIG. 6 is a schematic illustration of a slicing process when a first branch condition is encountered;
FIG. 7 is a schematic illustration of a second branching scenario encountered during slicing;
FIG. 8 is a schematic diagram of the front side of the skeleton superimposed with the original model;
fig. 9 is a schematic diagram of the back surface after the skeleton and the original model are superimposed.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.
The skeleton extraction method based on the topology optimized model specifically comprises the following steps:
1. firstly, a skeleton of a model needs to be extracted, wherein the model after a certain three-dimensional L-shaped stent is in a topological structure is taken as an embodiment, and the extraction process comprises the following specific steps:
1.1 model after topology optimization is completed as shown in fig. 1 and 2, each fixed constraint node p is recorded respectively i The deformation value at the fixed constraint node is the minimum deformation _ min;
1.2, reading out the maximum deformation value deformation _ max, and determining the coordinates of the maximum deformation point;
1.3 according to the size of the deformation, uniformly dividing the region between the resolution _ min and the resolution _ max into 14 sub-regions, which are marked as blocks B i (i =1,2, \ 8230;, 14) as shown in fig. 3;
1.4 starting from each fixed constraint node, respectively taking an x0y plane, a y0z plane and an x0z plane as a first slice;
1.5 slicing the model in x, y and z directions respectively by taking 5 times of grid unit size lambda as step length, and marking the slices as C j Taking only single connected regions during slicing (only considering multi-connected regions when a branch is encountered), where the slice in the z-direction is as shown in fig. 4;
1.6, judging whether a slice has no node of a block at all, and if so, starting from the previous slice, reducing the step size to lambda, and continuing slicing until the same condition is met. At this time, the coordinate value of the coordinate axis corresponding to the next slice (for example, when the slice starts from the x0y plane, the z-direction coordinate value of the slice is recorded) is recorded as the upper limit of the coordinate of the newly defined block in the direction of the axis, as shown in fig. 5;
1.7 judging whether there is some block node in some slice and there is no block node in the last slice, if there is, starting from the last slice, reducing the step size to lambda and then continuing to slice until meeting the same condition. At this time, recording 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 axis direction, as shown in fig. 5;
1.8, judging whether the situation that the projection area of a plane corresponding to a certain slice changes greatly suddenly compared with the previous slice exists in the slicing process; or, if the region corresponding to a slice is a multi-connected region and the previous slice is a normal single-connected region, it indicates that there is a branch in this portion. Defining the whole branch as a branch block, reducing the step length and obtaining a slice, and recording the coordinate value of the corresponding coordinate axis direction corresponding to the previous slice as the maximum coordinate value or the minimum coordinate value of the branch block in the direction, as shown in fig. 6 and 7;
1.9, judging whether the slice reaches the point of the maximum deformation value, if so, turning to 1.10, otherwise, turning to 1.5 to continue iteration;
1.10 re-blocking the model according to the recorded slices, defining the new block as B i， The size of i depends on the number of blocks;
1.11 from each constraint node p, respectively i Starting to search the next newly defined block;
1.12 calculating the coordinate value of the center point of the new block according to the recorded coordinate value of the slice by an averaging method, and recording the center point as M i ；
1.13 record all mesh nodes in the new block as T k The value of k depends on the number of nodes in the block;
1.14 calculating the distance dist between each grid node and the central point by a distance formula between the two points, and recording the grid node coordinate corresponding to the minimum value d of the dist as a key node in the block;
1.15 judging whether the point of the maximum deformation value is reached, if so, turning to 1.16, otherwise, starting from the block, and continuing iteration from 1.12 to the next block closest to the block;
1.16 connecting all the nodes in sequence to form a three-dimensional point diagram which is a part of a structural skeleton;
1.17 judging whether two recent blocks are encountered in the previous step, if yes, indicating that there is a branch block, turning to 1.11 to start the iteration again, and selecting a branch as the next block when the iteration encounters a branch condition;
1.18, judging whether the steps are carried out on all the fixed constraint nodes or not, if not, turning to 1.11 to continue iteration;
1.19 removing repeated nodes to obtain a complete skeleton of the structure.
2. The following describes in detail the operational steps of the skeleton extraction process:
2.1 analyzing the original model by using Ansys Workbench software, setting the size of a grid to be 1mm, and carrying out topology optimization on the model, wherein the topology optimization is shown in a figure 1 and a figure 2;
2.2, extracting the coordinate values and the deformation values of the optimized skeleton nodes through Ansys Workbench software, and recording the coordinate values and the deformation values by using Excel;
2.3 according to the definition of the blocks, grouping the nodes according to the deformation size;
2.4 according to the slice definition and the steps, defining a new block after screening in Excel, and recording the coordinates of the key slice in the corresponding direction;
2.5 according to the recorded coordinate value, using formula
To calculate the center point M of each block i C represents the corresponding coordinate value of the slice, i is related to the number of blocks;
2.6 according to
Calculate each node T in the block k (the size of k depends on the number of nodes in the block) and the center pointM i The distances between the nodes are arranged in ascending order, the minimum value of dist _ k is recorded as d, and the coordinate corresponding to d is recorded as the coordinate of the key node;
2.7 repeating the steps in 2.6 for each block, and recording all key nodes;
2.8 arranging each node according to the connection sequence, drawing a node point diagram, wherein the node point diagram is a skeleton of the structure;
2.9 overlapping the model with the original model to obtain a graph 8 and a graph 9;
2.10 writing APDL codes, obtaining static stiffness matrixes of all nodes by inputting node numbers, and recording all physical attributes as shown in Table 1;
TABLE 1
2.11 in summary, skeleton extraction and subsequent partial analysis of the structure can be achieved by the steps described in the present invention.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that various changes and modifications can be made by those skilled in the art without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (4)
1. A structural design method based on a skeleton attribute extraction technology is characterized by comprising the following steps: the proposed skeleton not only contains the geometrical information of the structure, but also contains the physical information of the skeleton, and provides a theoretical basis for the subsequent analysis according to the skeleton on the basis of the extraction and analysis of the physical properties, and the method specifically comprises the following steps:
1) Establishing a skeleton model: the method comprises the steps of adopting key physics and geometric information represented by structural key nodes to establish a storage model of the key information, and enabling data information stored by the model to be skeleton attribute information;
2) Obtaining skeleton model information: carrying out finite element division and topological optimization on the original structure of the design target to obtain a model after topological optimization;
3) Partitioning and slicing a geometric structure of a topological structure model obtained by topological optimization, redefining partitioning after slicing is finished, and dividing the model into a plurality of parts to facilitate analysis;
4) Reading the number of the finite element grid nodes contained in each redefined block, and searching the grid node closest to the center point of the block in each block as a key node;
5) Searching a constraint point formed by connecting the structure with the outside as a key node;
6) Extracting key physical information and performance information of key node positions, stress strains, force conduction, amplitudes of all orders and slicing quality;
7) Starting from the constraint point, connecting key nodes according to slice information, and determining the spatial geometric position and form of the skeleton;
8) And analyzing the skeleton, providing coordinate values and deformation of each node, calculating to obtain a static stiffness matrix of each node, and determining the performance conditions meeting the performance requirements.
2. The structural design method based on the skeleton attribute extraction technology of claim 1, wherein: in step 3), respectively recording each fixed constraint node p for the topological structure model after the topological optimization is completed i The deformation value at the fixed constraint node is the minimum deformation value; reading out the maximum deformation value, and determining the coordinates of the maximum deformation point; according to the deformation size, uniformly dividing the area between the minimum value and the maximum deformation value into a plurality of sub-areas, and marking as a block B i I =1,2, \ 8230;, n; starting from each fixed constraint node, respectively taking an xoy plane, a yoz plane and an xoz plane as first slices; taking the multiple of the grid unit size lambda as a step length, slicing the model in the three directions of x, y and z, and marking the slices as C j In the slicing process, if notA branch case is encountered and only a single connected region is taken.
3. The structural design method based on the skeleton attribute extraction technology of claim 1, wherein: and 4) calculating the distance between each finite element grid node and the central point through a distance formula between the two points, recording the coordinate of the finite element grid node corresponding to the minimum value of the distance, and taking the node as a key node in the block.
4. The structural design method based on the skeleton attribute extraction technology of claim 1, wherein: the specific method of step 8) comprises the following steps:
(1) Analyzing the original model by using finite element analysis software, setting the size of a grid, carrying out topology optimization on the model, extracting the coordinate values and the deformation values of each optimized framework node by using the finite element analysis software, and recording; according to the definition of the blocks, grouping the nodes according to the deformation size;
(2) According to the slice definition and the steps, a new block is defined after screening in the record file, and the coordinates of the key slice in the corresponding direction are recorded;
calculating the coordinates of the center point of each block according to the recorded coordinate values; calculating each node in the block by considering the distance between the node number in the block and the central point, arranging the nodes in the block in an ascending order, recording the minimum value of the distance between the node number in the block and the central point as d, and recording a coordinate corresponding to the d as a coordinate of a key node;
(3) And arranging each node according to the connection sequence, drawing each node by using numerical processing software, and obtaining a point line graph which is a skeleton of the structure.
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