A hybrid optimization design method for lattice structures

Abstract

The present invention discloses a hybrid optimization design method for a lattice structure, which comprises the following steps: S1, topological optimization; S2, skeleton and node extraction; S3, member identification; S4, member size optimization. The present invention first obtains the basic configuration of the structure through continuum topological optimization. Continuum topological optimization has a very high computational efficiency, and this process usually only takes a few minutes to dozens of minutes to complete. Then, the skeleton of the structure is extracted and the rod system structure is identified by means of computer graphics. By comprehensively applying two different optimization methods, namely continuum topological optimization and member size optimization, that is, through hybrid optimization, the optimization efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of building structures, and specifically to a hybrid optimization design method for lattice structures. Background Art

[0002] Lattice structures are very common in structural design. From the perspective of finite elements, they mainly refer to structural systems composed only of line elements. For example, transmission towers, steel trusses, steel frames, etc. all belong to lattice structures. The design scheme of lattice structures (mainly the node positions, the connection methods of members, and the cross-sectional dimensions of components) has a great impact on their mechanical properties. What is usually pursued in design is to make the structure have the strongest external force resistance (usually expressed by the minimum compliance) under the condition of a fixed material consumption, or to minimize the material consumption of the structure under the premise of meeting the design requirements.

[0003] Currently, for the optimization design of lattice structures, the discrete topology optimization method is mostly used, and its calculation process is cumbersome and time-consuming, with low efficiency and certain limitations. Summary of the Invention

[0004] (I) Technical Problems to be Solved

[0005] Aiming at the deficiencies of the prior art, the present invention provides a hybrid optimization design method for lattice structures, which has the advantages of high optimization efficiency, etc., to solve the problems of cumbersome and time-consuming size optimization process and low efficiency.

[0006] (II) Technical Solutions

[0007] To achieve the above-mentioned purpose of high optimization efficiency, the present invention provides the following technical solutions:

[0008] A hybrid optimization design method for lattice structures includes the following steps:

[0009] S1. Topology Optimization

[0010] Discretize the materials in the optimization space into a finite number of elements (shell elements or solid elements), and the structural member shape or hole shape can be used as the optimization object for topology optimization. Through continuum topology optimization, the basic configuration of the structure is obtained, and the remaining elements form the final topology scheme, thus realizing topology optimization.

[0011] S2. Skeleton and Node Extraction

[0012] Extract the structural skeleton and node information according to the results of the previous topology optimization. The skeleton is the geometric feature of the component obtained by condensing the solid elements obtained by continuum topology optimization, and the node is the connection point between components. The node connection methods between components are generally of two types: hinged connection and fixed connection.

[0013] S3. Member Identification

[0014] Based on the nodes identified in S2, in this step, it is determined which nodes are connected by straight members. If it is determined that there is a straight member connecting two nodes, it is considered that there is a member connection between these two nodes; otherwise, it is considered that there is no member connection between these two nodes. By traversing and judging any two nodes among all the nodes in step S2, all the members can be identified.

[0015] S4. Member Size Optimization

[0016] Perform member cross-sectional size optimization on the lattice structure composed of straight members. In this step, the interface sizes of the various members of the structure are used as design variables (for example, if the cross-section of the member is rectangular, the design variables are the height and width of the rectangle), the lightest total weight of the materials used in the structure is used as the objective function, and the displacement limit values required by the structural design, etc. are used as constraint conditions to perform size optimization design.

[0017] Perform member cross-sectional size optimization on the lattice structure composed of straight members, integrate the two optimizations involved in a complete optimization analysis into one optimization task, use topology optimization to obtain the initial configuration, and then use shape optimization to refine and process local areas.

[0018] Preferably, in step S2, vertical members (columns) and horizontal members (beams) of the same length should be used and staggered within the corresponding space.

[0019] Preferably, in step S2, the connection methods between the skeleton and the nodes can be divided into: bent frame, a gable frame formed by columns fixed to the foundation and horizontally hinged to the roof truss beam, double-hinged gable frame, and a gable frame where the upper parts of two columns are integrally fixed to the beam and the lower parts are hinged to the foundation.

[0020] Preferably, in step S3, the building node details are drawn with a larger scale to clearly show the local details of the building structure, so as to express the construction method, dimensions, mutual relationships of the components, and building materials.

[0021] Preferably, in step S4, the node coordinates and member connection information of the rod system structure are recorded, and further member size optimization can be performed.

[0022] (III) Beneficial Effects

[0023] Compared with the prior art, a lattice structure hybrid optimization design method provided by the present invention has the following beneficial effects:

[0024] 1. The lattice structure hybrid optimization design method selects a solid structure with a fixed-end constraint at the left end of the structure. Two concentrated loads act equidistantly on the upper edge of the structure. The outermost unit layers on the upper, lower, and right sides of the structure are regarded as fixed domains that do not participate in optimization, and other internal units are regarded as design domains for topology optimization. The purpose of this treatment is to ensure that the outer frame around the structure always exists during the optimization process. Then, by optimizing the two dimensions of the inclined support topology layout and the specific cross-sectional dimensions of the components, the continuous optimization of the solid structure is ensured.

[0025] 2. The lattice structure hybrid optimization design method first performs continuum topology optimization to obtain a better topological configuration, then extracts the skeleton of this topological configuration and identifies the nodes, further obtains a truss structure through the method of computer graphics, and finally performs size optimization by adjusting the cross-sectional dimensions of the truss structure components. This method combines the advantages of continuum topology optimization and size optimization. The above-mentioned hybrid optimization process is optimized from two dimensions, namely the inclined support topology layout and the specific cross-sectional dimensions of the components. The entire process only takes a few minutes and the efficiency is very high. Description of the Drawings

[0026] Figure 1 Schematic diagram of the first type of the optimization change process of the support system in the embodiment of the present invention.

[0027] Figure 2 Schematic diagram of the second type of the optimization change process of the support system in the embodiment of the present invention.

[0028] Figure 3 Schematic diagram of the third type of the optimization change process of the support system in the embodiment of the present invention.

[0029] Figure 4 Schematic diagram of the fourth type of the optimization change process of the support system in the embodiment of the present invention.

[0030] Figure 5 Schematic diagram of the fifth type of the optimization change process of the support system in the embodiment of the present invention.

[0031] Figure 6 Schematic diagram of the sixth type of the optimization change process of the support system in the embodiment of the present invention.

[0032] Figure 7 Schematic diagram of the first type of the optimization change process of the support size in the embodiment of the present invention.

[0033] Figure 8 Schematic diagram of the second type of the optimization change process of the support size in the embodiment of the present invention.

[0034] Figure 9 Schematic diagram of the design domain of the support system optimization in the embodiment of the present invention. Detailed Embodiments

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] Embodiment

[0037] See the attached Figures 1-9 , the lattice structure hybrid optimization design method provided by the present invention includes the following steps:

[0038] S1. Topology optimization

[0039] Discretize the materials in the optimization space into a finite number of elements (shell elements or solid elements). The optimization object can be the shape of the structural member or the hole shape to perform topology optimization. Through continuum topology optimization, the basic configuration of the structure is obtained, and the remaining elements form the final topology scheme, thereby realizing topology optimization.

[0040] S2. Skeleton and node extraction

[0041] Extract the structural skeleton and node information according to the results of the previous step of topology optimization. The skeleton is the geometric feature of the member obtained by condensing the solid elements obtained by continuum topology optimization, and the node is the connection point between the members. The connection methods between the nodes of the members are generally hinge connection and fixed connection.

[0042] S3. Member identification

[0043] Based on the nodes identified in S2, determine in this step which nodes are connected by straight bars. If it is determined that there is a straight bar connection between two nodes, it is considered that there is a member connection between these two nodes; otherwise, it is considered that there is no member connection between these two nodes. By traversing and judging any two nodes among all the nodes in step S2, all the members can be identified.

[0044] S4. Member size optimization

[0045] Optimize the cross-sectional dimensions of the members of the lattice structure composed of straight bars. In this step, the interface dimensions of each member of the structure are used as design variables (for example, if the cross-section of the member is rectangular, the design variables are the height and width of the rectangle), the lightest total weight of the materials used in the structure is used as the objective function, and the displacement limit values required by the structure design are used as the constraint conditions for size optimization design.

[0046] In step S2, vertical members (columns) and horizontal members (beams) of the same length should be taken and placed alternately within the corresponding space. In step S2, the connection methods of the framework and nodes can be divided into: bent frame, a portal frame formed by columns fixed to the foundation and horizontally hinged to the roof truss beam; double-hinged portal frame, a portal frame where the upper parts of two columns are integrally fixed to the beam and the lower parts are hinged to the foundation. In step S3, the building node details are drawn with a larger scale to clearly show the local details of the building structure, so as to express the construction practice, dimensions, the relationship between components, and building materials. In step S4, the node coordinates and member connection information of the bar system structure are recorded, and further component size optimization can be carried out.

[0047] Implementation steps of the lattice structure hybrid optimization design method:

[0048] Appendix Figure 9 A solid structure of 60mm×30mm×1mm is shown. The left end of the structure is a fixed-end constraint. Two concentrated loads of 1200N and 1200N are applied at equal intervals on the upper edge of the structure. The material properties are as follows: Young's modulus E = 210MPa, Poisson's ratio υ = 0.3, and mass density ρ = 7800kg / m3. The design domain is divided into 60×30 square elements with a side length of 1mm. The displacement constraint is that the displacement limit of the right lower endpoint of the structure does not exceed 1mm. The outermost unit layers on the upper, lower, and right sides of the structure are regarded as fixed domains that do not participate in optimization, and other internal units are regarded as the design domain for topology optimization. The purpose of this treatment is to ensure that the outer frame of the structure always exists during the optimization process.

[0049] Here, in order to ensure that the four-side frames of the design domain shown in the attached drawings always exist during the optimization process, we improve the original topology optimization and can adopt two optional methods: (1) Manually set the sensitivity of these units to a large value to ensure that they will not be deleted during the optimization process. (2) Directly set the value of these units in the next iteration step to 1 (i.e., representing it as a solid element) during the iterative process.

[0050] After obtaining Figures 1-6 the bar system structure shown, the node coordinates and member connection information of the bar system structure are recorded, and further component size optimization can be carried out. The results obtained are as shown in Figures 7-8 shown. Among them, Figure 7 is the same bar system structure as Figure 6 , and Figure 8 is the optimized bar system structure.

[0051] By selecting the solid structure, with the left end of the structure being a fixed-end constraint and two concentrated loads acting equidistantly on the upper edge of the structure, the outermost unit layers on the upper, lower, and right sides of the structure are regarded as fixed domains that do not participate in the optimization, and other internal units are regarded as the design domain for topology optimization. The purpose of this treatment is to ensure that the outer frame around the structure always exists during the optimization process. Then, by optimizing in two dimensions, namely the topological layout of the diagonal bracing and the specific cross-sectional dimensions of the components, the continuous optimization of the solid structure is ensured. The skeleton and nodes are extracted according to the bearing capacity of actual production, and a portal-shaped planar framework is formed by vertical members (columns) and horizontal members (beams). The individual portal frames are connected into a three-dimensional space by longitudinal beams. The node connection methods between the members generally have two types: hinged connection and fixed connection. Finally, the shape and dimensions of the members are selected based on the skeleton and nodes. The cross-section and axis of the member are described by the solid structure. After selecting a certain number of members, the truss structure is obtained through the method of computer graphics. Using truss recognition is a process of continuously optimizing the solid structure. This method combines the advantages of continuum topology optimization and size optimization. The above-mentioned hybrid optimization process is optimized in two dimensions, that is, the topological layout of the diagonal bracing and the specific cross-sectional dimensions of the components. The entire process only takes a few minutes, and the efficiency is very high.

[0052] In the above embodiments of the present invention, first, the basic configuration of the structure is obtained through continuum topology optimization. Continuum topology optimization has a very high computational efficiency, and this process usually only takes a few minutes to dozens of minutes to complete. Then, the skeleton of the structure is extracted through the method of computer graphics and the truss structure system is recognized. At this time, the structure skeleton only includes straight rods suitable for building structure design. On this basis, the cross-sectional dimensions of the components of the lattice structure composed of straight rods are optimized. It can be seen from the above steps that two different optimization methods, namely continuum topology optimization and component size optimization, are comprehensively used here, that is, through hybrid optimization, the optimization efficiency is improved.

[0053] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A hybrid optimization design method for lattice structures, characterized in that, It includes the following steps: S1. Topology optimization Discretize the materials in the optimization space into a finite number of elements, take the shape of structural members or holes as the optimization object to perform topology optimization, obtain the basic configuration of the structure through continuum topology optimization, and the remaining elements constitute the final topology scheme, thereby realizing topology optimization; S2. Skeleton and node extraction Extract the structural skeleton and node information according to the result of the previous topology optimization. The skeleton is the geometric feature of the member obtained by condensing the solid elements obtained by continuum topology optimization, and the node is the connection point between members; there are two types of node connection methods between members: hinged connection and fixed connection; S3. Member identification Based on the nodes identified in S2, judge which nodes are connected by straight bars. If it is judged that there is a straight bar connection between two nodes, it is considered that there is a member connection between these two nodes, otherwise it is considered that there is no member connection between these two nodes; traverse and judge any two nodes among all the nodes in step S2 to identify all the members; S4. Member size optimization Optimize the cross-sectional dimensions of the members of the lattice structure composed of straight bars. Take the cross-sectional dimensions of each member of the structure as the design variables, take the lightest total weight of the materials used in the structure as the objective function, and take the displacement limit value required by the structural design as the constraint condition to carry out size optimization design.

2. The lattice structure hybrid optimization design method according to claim 1, characterized in that In step S2, vertical members and horizontal members of the same length are taken and staggered and placed inside the corresponding space.

3. The lattice structure hybrid optimization design method according to claim 1, characterized in that In step S2, the connection methods of the skeleton and nodes are divided into: bent frame, a gable frame formed by columns fixed to the foundation and horizontally hinged to the roof truss beam, double-hinged gable frame, and a gable frame in which the upper parts of two columns are fixed to the beam as a whole and the lower parts are hinged to the foundation.

4. The lattice structure hybrid optimization design method according to claim 1, characterized in that In step S3, it also includes building node details. The building node details are drawn with a larger scale for the local details of the building structure to express the construction practice, dimensions, mutual relationship of components and building materials.

5. The lattice structure hybrid optimization design method according to claim 1, characterized in that In step S3, record the node coordinates and member connection information of the bar system structure, and further perform member size optimization according to step S4.

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