A thin-walled stiffened structure optimization design method for WAAM additive manufacturing
By setting movable stiffener components and driving nodes on thin-walled structures using an explicit topology optimization method, the problems of numerous design variables and process constraints in the optimization of existing thin-walled stiffened structures are solved, and efficient optimization design of thin-walled stiffened structures is realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- DALIAN UNIV OF TECH
- Filing Date
- 2023-04-18
- Publication Date
- 2026-06-02
AI Technical Summary
Existing optimization methods for thin-walled stiffened structures suffer from numerous design variables, difficulty in adding process constraints, and challenges in controlling feature dimensions.
An explicit topology optimization method is adopted. By setting movable and deformable stiffener components on the target thin-walled structure, an explicit description model is determined. Driving nodes are set at the joints of adjacent stiffener components to construct an explicit topology optimization model. The driving nodes and geometric parameters are iteratively adjusted to ensure the connectivity of the stiffened structure path and optimize the design variables to achieve topology optimization of the thin-walled stiffened structure.
The number of design variables was reduced, the difficulty of adding process constraints was simplified, the controllability of feature dimensions was improved, and efficient optimization design of thin-walled stiffened structures was achieved.
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Figure CN116844667B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of structural optimization technology, and more specifically, to a method for optimizing the design of thin-walled stiffened structures for WAAM additive manufacturing. Background Technology
[0002] Thin-walled structures, due to their high load-bearing efficiency, light weight, and good spatial flexibility, are widely used in critical structural components of spacecraft such as satellites, manned spacecraft, and space stations. To enhance the load-bearing capacity of thin-walled structures, numerous experts and scholars have employed various methods over the past few decades to analyze and improve their strength, stiffness, and stability, identifying thin-walled stiffened structures as one of the most effective and cost-efficient structural forms. Currently, the main topology optimization methods for thin-walled stiffened structures include: First, optimizing the shape and size of the stiffeners using a framework for designing and optimizing curved stiffened plate structures on complex multi-functional aircraft structures; second, using simulated annealing and genetic algorithms to optimize the curved trajectories of the skin fibers and stiffeners in curved grid-stiffened composite plates; and third, improving the adaptive morphogenesis algorithm and combining it with a hybrid genetic algorithm and robust optimization algorithm to determine the optimal geometry of the stiffened plate.
[0003] However, the optimization methods for the aforementioned thin-walled stiffened structures are usually implicit topology optimization methods based on background grid pixel units or growth-type optimization algorithms that rely on the background structure. These methods suffer from problems such as numerous design variables, difficulty in adding process constraints, and difficulty in controlling feature sizes. Summary of the Invention
[0004] In view of this, the purpose of this application is to provide an optimization design method for thin-walled stiffened structures for WAAM additive manufacturing, so as to solve the problems of numerous design variables, difficulty in adding process constraints, and difficulty in controlling feature dimensions in existing thin-walled stiffened structure optimization methods.
[0005] In a first aspect, embodiments of this application provide a method for optimizing the design of thin-walled stiffened structures for WAAM additive manufacturing, including:
[0006] Multiple movable and deformable rib components are set on the base model corresponding to the target thin wall, and each rib component is used to describe the rib of a thin wall stiffener.
[0007] For each rib assembly, determine the explicit description model corresponding to that rib assembly. The explicit description model includes the geometric parameters of the rib assembly.
[0008] Drive nodes are set at the joints of adjacent stiffener components. An explicit topology optimization model is constructed based on the set multiple drive nodes and the explicit description model. The explicit topology optimization model includes design variables, which include the coordinates of each drive node and the geometric parameters of the stiffener components.
[0009] Iteratively adjust the coordinates and geometric parameters of each driving node to determine the sensitivity of the explicit topology optimization model under different values;
[0010] When the sensitivity meets the convergence condition, the value of the design variable at this time is taken as the topology optimization result of the thin-walled stiffened structure.
[0011] Optionally, determining the explicit description model corresponding to the rib component includes: determining the skeleton description equation, mid-surface description equation, and outer boundary contour equation corresponding to the rib component; the skeleton description equation, mid-surface description equation, and outer boundary contour equation together constitute the explicit description model corresponding to the rib component.
[0012] Optionally, an explicit topology optimization model is constructed based on multiple driving nodes and an explicit description model, including: determining the coordinates of each driving node and the geometric parameters of the stiffener components as design variables, and determining the constraints and optimization objectives corresponding to the thin-walled stiffened structure; constructing constraint functions based on the design variables and constraints, and constructing objective functions based on the design variables and optimization objectives; and constructing an explicit topology optimization model by means of constraint functions, objective functions, and an explicit description model.
[0013] Optionally, the coordinates and geometric parameters of each driving node are iteratively adjusted to determine the sensitivity of the explicit topology optimization model under different values. This includes: determining the sensitivity calculation formula corresponding to the explicit topology optimization model, which includes a first sensitivity formula corresponding to the objective function and a second sensitivity formula corresponding to the constraint function; inputting the iteratively adjusted coordinates and geometric parameters of each driving node into the first sensitivity formula and the second sensitivity formula to determine the first sensitivity corresponding to the objective function and the second sensitivity corresponding to the constraint function, respectively; and constructing the sensitivity of the explicit topology optimization model from the first sensitivity and the second sensitivity.
[0014] Optionally, after taking the value of the design variable as the topology optimization result of the thin-walled stiffened structure when the sensitivity meets the convergence condition, the method further includes: deleting components with dimensions smaller than the size threshold from the stiffener components while ensuring the connectivity of the stiffened structure.
[0015] Optionally, multiple movable and deformable rib components are set on the base model corresponding to the target thin wall, including: obtaining the thin wall size of the target thin wall; determining the number of rib components and the size of each rib component based on the thin wall size; and setting the multiple rib components on the base model corresponding to the target thin wall according to the initial structural constraints.
[0016] Optionally, when the sensitivity meets the convergence condition, the value of the design variable at this time is taken as the topology optimization result of the thin-walled stiffened structure, including: when the sensitivity meets the convergence condition, performing a finite element model verification analysis on the value of the design variable to determine whether the value of the design variable meets the constraint conditions and optimization objectives; if it meets the constraint conditions and optimization objectives, the value of the design variable at this time is taken as the topology optimization result of the thin-walled stiffened structure.
[0017] Secondly, embodiments of this application also provide a thin-walled stiffened structure optimization design device for WAAM additive manufacturing, the device comprising:
[0018] The component setting module is used to set multiple movable and deformable rib components on the base model corresponding to the target thin wall. Each rib component is used to describe the rib of a thin wall stiffener.
[0019] The description model determination module is used to determine the explicit description model corresponding to each rib component. The explicit description model includes the geometric parameters of the rib component.
[0020] The optimization model determination module is used to set driving nodes at the joints of adjacent stiffener components, and to construct an explicit topology optimization model based on the set multiple driving nodes and the explicit description model. The explicit topology optimization model includes design variables, which include the coordinates of each driving node and the geometric parameters of the stiffener components.
[0021] The sensitivity calculation module is used to iteratively adjust the coordinates and geometric parameters of each driving node to determine the sensitivity of the explicit topology optimization model under different values.
[0022] The optimization result determination module is used to take the value of the design variable as the topology optimization result of the thin-walled stiffened structure when the sensitivity meets the convergence condition.
[0023] The embodiments of this application bring the following beneficial effects:
[0024] This application provides a method for optimizing the design of thin-walled stiffened structures for WAAM additive manufacturing. It describes the geometry and position of stiffeners using an explicit description model of the stiffener components, and sets driving nodes at the joints of adjacent stiffener components to achieve path connectivity within the stiffened structure. The stiffening path is adjusted by modifying the coordinates of the driving nodes and the geometric parameters of the stiffener components. The sensitivity of the explicit topology optimization model is used to determine whether the iteratively adjusted design variables have reached their optimal state, thereby achieving topology optimization of the thin-walled stiffened structure. Compared with existing thin-walled stiffened structure optimization methods, this method solves the problems of numerous design variables, difficulty in adding process constraints, and difficulty in controlling feature dimensions in existing thin-walled stiffened structure optimization methods.
[0025] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description
[0026] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0027] Figure 1 A flowchart is shown below illustrating the thin-walled stiffened structure optimization design method for WAAM additive manufacturing provided in this application embodiment;
[0028] Figure 2 A structural schematic diagram of the rib assembly layout provided in an embodiment of this application is shown;
[0029] Figure 3 A geometric description schematic diagram of the straight rib assembly provided in the embodiments of this application is shown;
[0030] Figure 4 This paper shows a schematic diagram of the outer boundary of the linear rib assembly provided in an embodiment of this application;
[0031] Figure 5 A schematic diagram of the layout structure of the rib assembly and drive node provided in the embodiments of this application is shown;
[0032] Figure 6 A schematic diagram showing the preliminary results of topology optimization of the thin-walled stiffened structure provided in the embodiments of this application is illustrated.
[0033] Figure 7 A schematic diagram of the structure of the thin-walled stiffened structure optimization design device for WAAM additive manufacturing provided in this application embodiment is shown. Detailed Implementation
[0034] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. Based on the embodiments of this application, every other embodiment obtained by those skilled in the art without inventive effort falls within the scope of protection of this application.
[0035] It is worth noting that prior to this application, thin-walled structures, due to their high load-bearing efficiency, light weight, and good spatial flexibility, were widely used in important structural components of spacecraft such as satellites, manned spacecraft, and space stations. To enhance the load-bearing capacity of thin-walled structures, numerous experts and scholars have analyzed and enhanced their strength, stiffness, and stability through various methods over the past few decades, identifying thin-walled stiffened structures as one of the most effective and cost-efficient structural forms. Currently, the topology optimization methods for thin-walled stiffened structures mainly include the following: First, the EBF3PanelOpt framework for optimizing the shape and size of stiffeners is used to design and optimize curved stiffened plate structures on complex multi-functional aircraft structures; second, simulated annealing and genetic algorithms are used to optimize the curved trajectories of the skin fibers and stiffeners of curved grid-stiffened composite plates; third, an improved adaptive morphogenesis algorithm is combined with a hybrid genetic algorithm and robust optimization algorithm to determine the optimal geometry of the stiffened plate. However, the optimization methods for the aforementioned thin-walled stiffened structures are usually implicit topology optimization methods based on background grid pixel units or growth-type optimization algorithms that rely on the background structure. These methods suffer from problems such as numerous design variables, difficulty in adding process constraints, and difficulty in controlling feature sizes.
[0036] Based on this, this application provides a method for optimizing the design of thin-walled stiffened structures for WAAM additive manufacturing, so as to reduce the number of design variables and the difficulty of adding process constraints, and improve the controllability of feature dimensions.
[0037] Please see Figure 1 , Figure 1 This is a flowchart illustrating an optimization design method for thin-walled stiffened structures in WAAM additive manufacturing, provided as an embodiment of this application. Figure 1 As shown in the embodiments of this application, the method for optimizing the design of thin-walled stiffened structures for WAAM additive manufacturing includes:
[0038] Step S101: Set multiple movable and deformable rib components on the base model corresponding to the target thin wall.
[0039] In this step, the target thin wall can refer to the thin-walled structure to be reinforced. For example, the target thin wall could be the tank structure of a satellite.
[0040] The substrate model can refer to the three-dimensional model of the target thin wall.
[0041] A stiffener assembly can refer to an assembly used to characterize a stiffener. Each stiffener assembly describes the stiffener of a single thin-walled stiffener.
[0042] In the embodiments of this application, when optimizing the design of a thin-walled stiffened structure for WAAM additive manufacturing, multiple stiffener components can be set on the base model corresponding to the target thin wall. Each stiffener component can move and deform freely on the base model. By optimizing the position and size of the stiffener components, the optimized design of the thin-walled stiffener can be achieved.
[0043] In one optional embodiment, multiple movable and deformable rib components are set on the base model corresponding to the target thin wall, including: obtaining the thin wall size of the target thin wall; determining the number of rib components and the size of each rib component based on the thin wall size; and setting the multiple rib components on the base model corresponding to the target thin wall according to the initial structural constraints.
[0044] Specifically, when setting up multiple movable and deformable rib components, the thin-wall size of the target thin-walled structure is first determined so that an appropriate number of rib components and rib components of corresponding size can be selected according to the thin-wall size. This can improve the topology optimization efficiency of the thin-walled stiffened structure.
[0045] Furthermore, after determining the number and size of the rib components, multiple rib components are placed on the base model according to the initial structural constraints, which are determined by the structural characteristics of the target thin-walled structure itself. When setting up the rib components, different rib components can be arranged in a cross pattern, with one end of one rib component connected to one end of another, forming a cross array of rib components, i.e., the initial rib component layout.
[0046] The following reference Figure 2 Let's introduce the initial rib component layout.
[0047] Figure 2 A structural schematic diagram of the initial rib assembly layout provided in an embodiment of this application is shown.
[0048] like Figure 2As shown, the base model corresponding to the target thin wall is fan-shaped, and multiple rib components are set on the base model, forming an initial rib layout. Among them, the multiple rib components include rib component 211, rib component 212, and rib component 213.
[0049] Step S102: For each rib component, determine the explicit description model corresponding to that rib component.
[0050] In this step, the explicit description model can refer to the mathematical model that describes the outer contour of the rib assembly. The explicit description model includes the geometric parameters of the rib assembly.
[0051] In the embodiments of this application, the outer contour of each rib component in the Lagrange frame based on the Moving Morphable Component (MMC) can be explicitly described by its geometric parameters.
[0052] In one optional embodiment, determining the explicit description model corresponding to the rib component includes: determining the skeleton description equation, mid-surface description equation, and outer boundary contour equation corresponding to the rib component; the skeleton description equation, mid-surface description equation, and outer boundary contour equation together constitute the explicit description model corresponding to the rib component.
[0053] The following reference Figure 3 This section introduces the skeleton description equation and the mid-surface description equation.
[0054] Figure 3 A geometrical description of the straight rib assembly provided in an embodiment of this application is shown.
[0055] like Figure 3 As shown, linear skeleton The endpoint coordinates of the corresponding elongated rib components are respectively and in and The thickness of the stiffener assembly is denoted as t, the height of the stiffener assembly is denoted as h, and the mid-surface of the stiffener assembly is denoted as S0, n s Let represent the outward normal vector of the skeleton. The skeleton description equation is:
[0056]
[0057] The equation of the mid-surface is:
[0058]
[0059] In the above formula, μ∈[0,1] is a coefficient of a convex combination, and η∈[0,1] is a parameter introduced along the height direction.
[0060] The following reference Figure 4 Let's introduce the outer boundary profile equation.
[0061] Figure 4 A schematic diagram of the outer boundary of the linear rib assembly provided in an embodiment of this application is shown.
[0062] like Figure 4 As shown, the six faces of the rib assembly are designated S1, S2, S3, S4, S5, and S6, and the corresponding outer boundary contour equations for each face are:
[0063]
[0064]
[0065]
[0066]
[0067]
[0068]
[0069] In the above formula, n s (μ) represents the outward normal vector of the skeleton, and r∈[0,1] is an introduced characterization parameter along the thickness direction.
[0070] Thus, the skeleton description equation C s The mid-surface equation S0 and the six outer boundary profile equations together provide an explicit description of the stiffener assembly.
[0071] Step S103: Set a driving node at the joint of adjacent rib components, and construct an explicit topology optimization model based on the set driving nodes and the explicit description model.
[0072] In this step, the explicit topology optimization model includes design variables, which include the coordinates of each driving node and the geometric parameters of the rib assembly.
[0073] A driving node can refer to a node that connects two adjacent stiffener components. Driving nodes are used to connect stiffener structure paths and change the position and size of stiffener components.
[0074] Adjacent stiffener assemblies can refer to stiffener assemblies whose endpoints are adjacent. For example... Figure 1 The reinforcing ribs 211, 212 and 213 are adjacent to each other.
[0075] In this embodiment, after determining the explicit description model of the stiffener assembly, the geometric parameters of each stiffener assembly can be obtained. The stiffener assembly is then driven to move and deform on the thin-walled substrate model using the MMC topology optimization algorithm, thereby obtaining the optimal stiffener force transmission path. However, considering only mechanical properties, the optimal stiffener path is not necessarily continuous. When manufacturing non-continuous stiffener structures using arc additive manufacturing (WAAM) technology, repeated arc initiation and extinguishing can easily lead to crater collapse, significantly impacting the overall performance of the structure.
[0076] Therefore, to avoid repeated arc starting and extinguishing, it is necessary to ensure that the optimized stiffener structural path is connected. To this end, driving nodes are introduced at the joints of each stiffener assembly, and adjacent stiffeners are connected through shared driving nodes. Then, an optimization algorithm is used to drive the shared driving nodes to move, thereby changing the position of the stiffener assembly.
[0077] The following reference Figure 5 Let's introduce the driver node.
[0078] Figure 5 A schematic diagram of the layout structure of the rib assembly and drive node provided in the embodiments of this application is shown.
[0079] like Figure 5 As shown, adjacent stiffener components 211, 212, and 213 are connected via drive node 221, and other adjacent stiffener components are also connected via drive nodes. The initial stiffening structure layout is formed by multiple cross-placed stiffener components and multiple drive nodes. In this way, the entire path of the thin-walled stiffening structure is connected, which can avoid repeated arc initiation and extinguishing.
[0080] In one optional embodiment, an explicit topology optimization model is constructed based on multiple driving nodes and an explicit description model, including: determining the coordinates of each driving node and the geometric parameters of the stiffener assembly as design variables, and determining the constraints and optimization objectives corresponding to the thin-walled stiffened structure; constructing constraint functions based on the design variables and constraints, and constructing objective functions based on the design variables and optimization objectives; and constructing an explicit topology optimization model by means of the constraint functions, objective functions, and explicit description model.
[0081] Specifically, the optimization formula in the explicit topology optimization model includes design variables, objective function, and constraint function, and is expressed as follows:
[0082]
[0083] I = I(D);
[0084] g i (D)≤0,i=1,…,n;
[0085]
[0086] In the above formula, D represents the design variable vector, used to characterize the design variables; D N D represents a vector consisting of the coordinates of all driving nodes. C This represents the geometric parameters of all the rib components, such as thickness t, height h, and endpoint coordinates; I represents the objective function; g i (D) represents the i-th constraint function; This represents the permission set for design variable D.
[0087] First, determine the constraints and optimization objectives corresponding to the target thin-walled structure. Taking a satellite storage tank as an example, the constraint could be that the first-order frequency of the overall structure is not less than 30Hz, or that the thickness of the skin and stiffening structure varies from 1.5mm to 25mm. The optimization objective could be to minimize the weight of the supporting structure under load conditions. There can be one or more constraints and optimization objectives.
[0088] Then, the constraints are transformed into constraint functions, and the optimization objective is transformed into an objective function. Taking the optimization objective of minimizing the weight of the support structure under load conditions as an example, the objective function is the integral of weight, and the domain of integration of the objective function is the domain with respect to the design variables. The defined constraint functions, objective function, and explicit description model constitute the explicit topology optimization model. When the value of a certain design variable is adjusted, the entire initial stiffened structural layout will change accordingly, causing the result of the global explicit description model corresponding to the initial stiffened structural layout to change, thus determining the sensitivity of the explicit topology optimization model under the current value of the global explicit description model.
[0089] Step S104: Iteratively adjust the coordinates and geometric parameters of each driving node to determine the sensitivity of the explicit topology optimization model under different values.
[0090] In this step, to determine the optimal result for the thin-walled stiffened structure, the values of the design variables need to be continuously adjusted to determine the sensitivity of the explicit topology optimization model under different values of the design variables. Based on the sensitivity, the optimal value of the design variables for the thin-walled stiffened structure is determined. Here, an iterative adjustment method is adopted, continuously iterating the coordinates of the driving nodes to optimize their positions; and continuously iterating the geometric dimensions of the stiffener components to optimize the dimensional variables and obtain the optimal dimensional result of the stiffener components.
[0091] In one optional embodiment, iteratively adjusting the coordinates and geometric parameters of each driving node to determine the sensitivity of the explicit topology optimization model under different values includes: determining the sensitivity calculation formula corresponding to the explicit topology optimization model, the sensitivity calculation formula including a first sensitivity formula corresponding to the objective function and a second sensitivity formula corresponding to the constraint function; inputting the iteratively adjusted coordinates and geometric parameters of each driving node into the first sensitivity formula and the second sensitivity formula to determine the first sensitivity corresponding to the objective function and the second sensitivity corresponding to the constraint function respectively; and constructing the sensitivity of the explicit topology optimization model from the first sensitivity and the second sensitivity.
[0092] Specifically, in the stiffened structure topology optimization method based on the MMC framework, the first sensitivity formula corresponding to the objective function and the second sensitivity formula corresponding to the constraint function are determined as the sensitivity calculation formula for the explicit topology optimization model. This sensitivity calculation formula is as follows:
[0093]
[0094] In the above formula, Represents all outer boundaries of the reinforced structure. represents the outer boundary of the i-th stiffener, and nc represents the total number of stiffeners; Indicates the i-th outer boundary along The outward normal velocity field can be easily obtained because the boundary of each stiffener assembly can be determined through an explicit descriptive model.
[0095] Assuming the optimization objective is to minimize the weight of the supporting structure, then in the first sensitivity formula of the objective function, f(u,v) = ρ, where ρ represents the material density of the structure. The constraint condition is that the first-order frequency of the overall structure is not less than 30Hz. Therefore, in the second sensitivity formula of the constraint function:
[0096]
[0097] In the above formula, ε represents the elastic modulus; u represents the displacement field; v represents the virtual displacement; ":" represents the tensor symbol double dot product; ρu·v represents the computational correlation mass matrix; ω1 represents the fundamental frequency of the structure.
[0098] It should be noted that f(u,v) is different for different objective functions, and f(u,v) is also different for different constraint functions.
[0099] Step S105: When the sensitivity meets the convergence condition, the value of the design variable at this time is taken as the topology optimization result of the thin-walled stiffened structure.
[0100] In this step, when the difference in sensitivity between two consecutive iterations is less than the sensitivity threshold, the sensitivity is determined to meet the convergence condition. Therefore, the iteration of the design variables is stopped, and the current value of the design variables is taken as the topology optimization result. At this point, designers can directly extract the design variable vector at the end of the iteration and use script modeling to directly obtain the optimized design CAD model, avoiding the processing steps such as grayscale cell processing and geometric feature extraction required in traditional topology optimization methods.
[0101] The following reference Figure 6 This paper presents the preliminary results of topology optimization for thin-walled reinforced structures.
[0102] Figure 6 A schematic diagram showing the preliminary results of topology optimization of the thin-walled stiffened structure provided in the embodiments of this application is illustrated.
[0103] like Figure 6 As shown, the current position of each driving node is the result of topology optimization. The current position and current size of different rib components are also the result of topology optimization. Dashed lines represent rib components that cannot be produced due to insufficient thickness, while solid lines represent rib components that meet the design requirements. Solid lines of different thicknesses represent rib components of different sizes.
[0104] In an optional embodiment, when the sensitivity meets the convergence condition, the value of the design variable at this time is taken as the topology optimization result of the thin-walled stiffened structure, including: when the sensitivity meets the convergence condition, performing a finite element model verification analysis on the value of the design variable to determine whether the value of the design variable meets the constraint conditions and optimization objectives; if it meets the constraint conditions and optimization objectives, the value of the design variable at this time is taken as the topology optimization result of the thin-walled stiffened structure.
[0105] Specifically, after determining that the sensitivity meets the convergence condition, it is also necessary to verify the values of the design variables at this point. Taking the example above, the constraint condition can be that the first-order frequency of the overall structure is not less than 30Hz. Therefore, when verifying the thin-walled stiffened structure, it is necessary to analyze and verify the frequency of the thin-walled stiffening result. Assuming that the first-order frequency of the structure is determined to be 31.8Hz, it indicates that the design requirements are met. If the thin-walled stiffened structure also needs to meet the strength and stiffness requirements, it is also necessary to perform strength analysis and stiffness analysis verification on the topology optimization result of the thin-walled stiffened structure to determine whether the topology optimization result meets the strength and stiffness requirements respectively.
[0106] In an optional embodiment, after taking the value of the design variable as the topology optimization result of the thin-walled stiffened structure when the sensitivity meets the convergence condition, the method further includes: deleting components with a size smaller than the size threshold from the stiffener assembly while ensuring the connectivity of the stiffened structure.
[0107] Specifically, after obtaining preliminary results of topology optimization for the thin-walled stiffened structure, undersized stiffening components can be removed, provided that structural connectivity is maintained. Figure 6 The rib components corresponding to the dashed lines in the middle are used to obtain the final topology optimization result of the thin-walled stiffened structure.
[0108] As can be seen, this application proposes an explicit topology optimization method for thin-walled stiffened structures in WAAM additive manufacturing, based on the topology optimization framework of mobile deformable components. Unlike previous implicit topology optimization methods based on background mesh pixel units and growth-type optimization algorithms dependent on the background base structure, this application uses stiffener components with explicit geometric parameters as the basic unit for topology optimization. By introducing shared driving nodes for the stiffeners, the connectivity of the stiffened structure is controlled, thereby adapting to the process constraints of reducing arc start-up and extinguishing during WAAM additive manufacturing.
[0109] Compared with existing methods for optimizing thin-walled stiffened structures for WAAM additive manufacturing, this application describes the geometry and position of stiffeners using an explicit description model of stiffener components. Driving nodes are set at the joints of adjacent stiffener components to achieve path connectivity within the stiffened structure. The stiffening path is adjusted by modifying the coordinates of the driving nodes and the geometric parameters of the stiffener components. The sensitivity of the explicit topology optimization model is used to determine whether the iteratively adjusted design variables have reached their optimal state, thus achieving topology optimization of the thin-walled stiffened structure. This solves the problems of numerous design variables, difficulty in adding process constraints, and difficulty in controlling feature dimensions in existing thin-walled stiffened structure optimization methods.
[0110] Based on the same inventive concept, this application also provides a device for optimizing the design of thin-walled stiffened structures for WAAM additive manufacturing, corresponding to the optimization design method for thin-walled stiffened structures for WAAM additive manufacturing. Since the principle of the device in this application is similar to the optimization design method for thin-walled stiffened structures for WAAM additive manufacturing described above, the implementation of the device can refer to the implementation of the method, and the repeated parts will not be described again.
[0111] Please see Figure 7 , Figure 7 This is a schematic diagram of a thin-walled stiffened structure optimization design device for WAAM additive manufacturing, provided as an embodiment of this application. Figure 7 As shown, the thin-walled stiffened structure optimization design device 300 for WAAM additive manufacturing includes:
[0112] The component setting module 301 is used to set multiple movable and deformable rib components on the base model corresponding to the target thin wall, and each rib component is used to describe the rib of a thin wall stiffener.
[0113] The description model determination module 302 is used to determine the explicit description model corresponding to each rib component. The explicit description model includes the geometric parameters of the rib component.
[0114] The optimization model determination module 303 is used to set driving nodes at the joints of adjacent stiffener components, and to construct an explicit topology optimization model based on the set multiple driving nodes and the explicit description model. The explicit topology optimization model includes design variables, which include the coordinates of each driving node and the geometric parameters of the stiffener components.
[0115] The sensitivity calculation module 304 is used to iteratively adjust the coordinates and geometric parameters of each driving node to determine the sensitivity of the explicit topology optimization model under different values.
[0116] The optimization result determination module 305 is used to take the value of the design variable as the topology optimization result of the thin-walled stiffened structure when the sensitivity meets the convergence condition.
[0117] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.
[0118] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the shown or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.
[0119] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.
[0120] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.
[0121] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.
[0122] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The scope of protection of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. A method for optimizing the design of thin-walled stiffened structures for WAAM additive manufacturing, characterized by, include: Multiple movable and deformable rib components are set on the base model corresponding to the target thin wall, and each rib component is used to describe the rib of a thin wall stiffener. For each rib assembly, an explicit description model corresponding to the rib assembly is determined, and the explicit description model includes the geometric parameters of the rib assembly; A driving node is set at the joint of adjacent stiffener components. An explicit topology optimization model is constructed based on the set multiple driving nodes and an explicit description model. The explicit topology optimization model includes design variables, which include the coordinates of each driving node and the geometric parameters of the stiffener components. Iteratively adjust the coordinates of each driving node and the values of the geometric parameters to determine the sensitivity of the explicit topology optimization model under different values; When the sensitivity meets the convergence condition, the value of the design variable at this time is taken as the topology optimization result of the thin-walled stiffened structure; The construction of the explicit topology optimization model based on the configured multiple driver nodes and the explicit description model includes: The coordinates of each driving node and the geometric parameters of the stiffener assembly are determined as design variables, and the constraints and optimization objectives corresponding to the thin-walled stiffened structure are determined. A constraint function is constructed based on the design variables and constraints, and an objective function is constructed based on the design variables and the optimization objective. The explicit topology optimization model is composed of the constraint function, the objective function, and the explicit description model.
2. The method of claim 1, wherein, The determination of the explicit description model corresponding to the rib assembly includes: Determine the skeleton description equation, mid-surface description equation, and outer boundary profile equation corresponding to the rib assembly; The explicit description model corresponding to the rib component is composed of the skeleton description equation, the mid-surface description equation, and the outer boundary contour equation.
3. The method of claim 1, wherein, The iterative adjustment of the coordinates of each driving node and the values of the geometric parameters to determine the sensitivity of the explicit topology optimization model under different values includes: Determine the sensitivity calculation formula corresponding to the explicit topology optimization model, wherein the sensitivity calculation formula includes a first sensitivity formula corresponding to the objective function and a second sensitivity formula corresponding to the constraint function; The coordinates of each driving node after iterative adjustment and the values of the geometric parameters are input into the first sensitivity formula and the second sensitivity formula to determine the first sensitivity corresponding to the objective function and the second sensitivity corresponding to the constraint function, respectively. The sensitivity of the explicit topology optimization model is composed of the first sensitivity and the second sensitivity.
4. The method of claim 1, wherein, After stating that when the sensitivity satisfies the convergence condition, the value of the design variable at this time is taken as the topology optimization result of the thin-walled stiffened structure, the method further includes: While ensuring the connectivity of the stiffened structure, remove components with dimensions smaller than the size threshold from the stiffener assembly.
5. The method according to claim 1, characterized in that, The step of setting multiple movable and deformable rib components on the base model corresponding to the target thin wall includes: Obtain the thin-wall dimensions of the target thin-walled structure; The number of rib assemblies and the dimensions of each rib assembly are determined based on the thin-walled dimensions. Based on the initial structural constraints, multiple rib components are set on the base model corresponding to the target thin wall.
6. The method according to claim 1, characterized in that, When the sensitivity meets the convergence condition, the value of the design variable at this time is taken as the topology optimization result of the thin-walled stiffened structure, including: When the sensitivity meets the convergence condition, the values of the design variables are checked by a finite element model to determine whether the values of the design variables meet the constraints and optimization objectives. If the constraints and optimization objectives are met, the values of the design variables at this time will be used as the topology optimization results of the thin-walled stiffened structure.
7. A device for optimizing the design of thin-walled stiffened structures for WAAM additive manufacturing, characterized in that, include: The component setting module is used to set multiple movable and deformable rib components on the base model corresponding to the target thin wall. Each rib component is used to describe the rib of a thin wall stiffener. The description model determination module is used to determine the explicit description model corresponding to each rib component, wherein the explicit description model includes the geometric parameters of the rib component; The optimization model determination module is used to set driving nodes at the joints of adjacent stiffener components, and to construct an explicit topology optimization model based on the set multiple driving nodes and an explicit description model. The explicit topology optimization model includes design variables, which include the coordinates of each driving node and the geometric parameters of the stiffener components. The sensitivity calculation module is used to iteratively adjust the coordinates of each driving node and the values of the geometric parameters to determine the sensitivity of the explicit topology optimization model under different values. The optimization result determination module is used to take the value of the design variable as the topology optimization result of the thin-walled stiffened structure when the sensitivity meets the convergence condition. The optimization model determination module is specifically used for: The coordinates of each driving node and the geometric parameters of the stiffener assembly are determined as design variables, and the constraints and optimization objectives corresponding to the thin-walled stiffened structure are determined. A constraint function is constructed based on the design variables and constraints, and an objective function is constructed based on the design variables and the optimization objective. The explicit topology optimization model is composed of the constraint function, the objective function, and the explicit description model.