A lightweight design method for thin-walled shell structure based on topology optimization

Abstract

This invention discloses a lightweight design method for thin-walled shell structures based on topology optimization. The method includes: establishing an initial model of the thin-walled shell; meshing the initial model with finite element elements (FEM) and using FEM software to simulate environmental load conditions for structural strength analysis, examining the stress, deformation, and modal characteristics of the initial model; performing topology optimization on the initial model using FEM software; examining the element density optimization results and performing configuration adjustments on the topology-optimized structure; comparing the mass difference before and after optimization to check the effectiveness of the lightweight design; and using FEM software to perform numerical simulations of the high-speed motion forming process of the topology-optimized lightweight thin-walled shell and the initial model to evaluate the impact of the topology-optimized structure on the output product. This design method can achieve lightweighting of thin-walled shells while maintaining a single metallic material, achieving a balance between weight reduction and performance.

Description

Technical Field

[0001] This invention belongs to the field of lightweight structural design technology, specifically relating to a lightweight design method for thin-walled shell structures based on topology optimization. Background Technology

[0002] A shaped charge structure is an energy device that drives metal components to undergo intense plastic deformation under high-energy transient loads, forming a high-speed moving body in a very short time. The structure is as follows: Figure 1 As shown. The external constraint of this type of device—the thin-walled shell 1—is its key load-bearing and boundary constraint component. During energy release, it must withstand extremely high dynamic load pressure, which has a decisive impact on the forming quality, speed consistency, and overall energy conversion efficiency of the moving body.

[0003] Traditional high-energy load confinement components typically employ metal walls of a certain thickness, often accounting for 40-50% of the total system mass. This severely limits the device's portability, energy efficiency, and integration into precision load platforms. To achieve lightweighting, existing technologies attempt to introduce low-density metals (such as aluminum and titanium) or high-performance composite materials. However, these dissimilar material interfaces suffer from impedance mismatch, easily leading to stress wave reflection and energy loss at the interface. This disrupts the stability of internal physical processes, resulting in poor output performance. Existing lightweight design methods mainly include: overall lightweight material replacement, which can reduce weight but weakens the strength and stiffness of thin-walled shells, leading to uneven internal shock wave propagation and unbalanced forming process, thus reducing the performance of the moving body; composite materials or multi-material splicing, where stress concentration and wave impedance differences exist at interface joints or welded areas, easily causing shock wave field distortion and structural discontinuities, seriously affecting the stable forming of the moving body; overall structural thinning or local openings, sacrificing load-bearing sections to reduce weight, which significantly weakens the overall load-bearing capacity and structural stiffness of thin-walled shells, making them unable to withstand the huge impact loads during launch. In addition, unoptimized openings can cause severe stress concentration and may interfere with the uniform propagation of shock waves, making it impossible to achieve a balance between performance and lightweighting.

[0004] However, before achieving final energy output, the thin-walled shell must first withstand external loads throughout its entire life cycle. As the device is integrated into diverse mounting platforms, the varying operating environments present extreme and complex structural challenges: high-impact pulse loading environments require withstanding extremely high instantaneous acceleration and enormous centrifugal forces generated by high-speed rotation; continuous acceleration drive environments require addressing the structural fatigue risks caused by prolonged continuous acceleration and complex vibrations; and gravity delivery environments, while subject to relatively mild loads, still require ensuring impact reliability and structural integrity during deployment and separation.

[0005] Traditional thin-walled shell designs often adopt a conservative strategy to ensure versatility, using extreme peak load conditions as a uniform design benchmark. This design logic leads to performance redundancy and excessive mass in constrained components. While ensuring safety margins, it also brings significant negative effects: when applied to low-load platforms, the redundant weight becomes a huge burden, and excessive inertia and weight weaken the platform's response speed and operational flexibility, leading to material waste and increased costs.

[0006] The technical problem this invention aims to solve is to achieve lightweight thin-walled shells while maintaining a single metallic material, avoiding structural strength reduction and shock wave distortion caused by weight reduction, and achieving a balance between weight reduction and performance maintenance. Therefore, developing a lightweight structural optimization method that can be precisely controlled according to the mechanical environmental characteristics of specific application scenarios has become an urgent need in this field. An ideal design method should be able to achieve the optimal material distribution through mathematical means while ensuring structural integrity, thereby minimizing redundant mass. Summary of the Invention

[0007] This invention provides a lightweight design method for thin-walled shell structures based on topology optimization. This lightweight design method can achieve lightweighting of thin-walled shells while maintaining a single metal material, avoiding structural strength reduction and shock wave distortion caused by weight reduction, and achieving a balance between weight reduction and performance.

[0008] To achieve the above objectives, the present invention adopts the following specific technical solution:

[0009] A lightweight design method for thin-walled shell structures based on topology optimization, the lightweight design method comprising: Step 1: Establish the initial model of the thin-walled shell; Step 2: Divide the initial model into finite element meshes and use finite element software to simulate the structural strength under environmental load conditions, and check the stress, deformation and modes of the initial model. Step 3: Use topology optimization software to perform topology optimization on the initial model; Step 4: Review the unit density optimization results and perform configuration processing on the topology-optimized structure; Step 5: Compare the quality differences before and after optimization to check the effect of the lightweight design; Step 6: Use finite element software to perform numerical simulation of the high-speed motion forming process of the topology-optimized lightweight thin-walled shell and the initial model, and evaluate the effect of the topology-optimized structure on the output product.

[0010] Furthermore, in step three, the initial model is topology optimized using topology optimization software, specifically including: Create a shell element mesh; Apply material to a thin-walled shell, and set boundary constraints and load conditions; The thin-walled shell is divided into an optimized region L1 and a non-optimized region L2. The non-optimized region L2 is the key area for load transfer and retains the original structure to ensure that the load-bearing path and connection function of the structure are not affected during the optimization process. Set constraints and objective function; Perform material distribution optimization within the optimization region L1.

[0011] Furthermore, in step three, the optimization region L1 is divided according to the shock wave propagation characteristics, the load application area, and the structural functional requirements. The boundary conditions of the optimization region L1 satisfy the following relationship:

[0012] In the above formula, C is the shock wave velocity, t is the time it takes for the shock wave to reach the top of the metal part at the output end, and D is the inner diameter of the thin-walled shell.

[0013] Furthermore, in step three, constraints and the objective function are set, specifically including: Minimum flexibility is used as the response constraint to ensure structural stiffness; The optimization objective is to reduce the weight of the thin-walled shell, and the volume fraction is set to 0.3 as the response. In a two-dimensional structure, symmetric constraints are added to the thin-walled shell; Set minimum build size constraints to avoid the "checkerboard" phenomenon in density distribution.

[0014] Furthermore, the minimum build size constraint is set at 3-5 times the average cell size.

[0015] Furthermore, step four specifically includes: By selecting a relative unit density threshold and performing smoothing, a two-dimensional planar model of the material density distribution is obtained. Extracting contour features from a two-dimensional planar model; The three-dimensional model was reconstructed. During the reconstruction process, sharp corners were rounded to reduce stress concentration, and material homogenization was performed at dimensional steps on the connection path to optimize the structural rationality.

[0016] Furthermore, step five specifically includes: Finite element meshing is performed on the topology-optimized 3D model; Using the same constraints and loads as the initial model, a finite element verification analysis was performed to analyze the differences in stress and deformation compared to the initial model, ensuring that the optimized structure has the initial structural strength and meets the allowable conditions.

[0017] Furthermore, step six specifically includes: A comparative analysis was conducted on the velocity and aspect ratio of the moving body under the initial and optimized structures.

[0018] Furthermore, before establishing the initial model of the thin-walled shell, the thickness and length of the thin-walled shell are determined based on the charge structure.

[0019] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: 1. Maintain structural strength: The optimized thin-walled shell forms a skeletal load-bearing path, achieving a balance between lightweighting and strength maintenance, and avoiding the defect of "reducing weight means reducing strength".

[0020] 2. Eliminate interface problems: Use a single metal material design to avoid wave impedance differences and stress concentration caused by multi-material interfaces.

[0021] 3. Significant weight reduction: While maintaining output performance, the thin-walled shell achieves a weight reduction of nearly 50%. The reduction in weight improves the operational efficiency of the platform while maintaining the stability of high-speed flight body formation and the mechanical properties of the thin-walled shell.

[0022] 4. Complete and scalable: It proposes a system flow from topology optimization modeling to 3D reconstruction and simulation verification, which has good engineering feasibility and promotion value. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a shaped charge structure; Figure 2 This is a flowchart of the lightweight design method for thin-walled shell structures based on topology optimization according to the present invention; Figure 3 This is a schematic diagram of the initial model of a thin-walled shell. Figure 4 This is a schematic diagram of a two-dimensional model of the thin-walled shell after topology optimization. Figure 5 This is a cross-sectional schematic diagram of the thin-walled shell model after 3D reconstruction. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the description of this invention, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances. Furthermore, in the description of this invention, unless otherwise stated, "multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0026] Topology optimization technology provides an ideal solution for this invention. It breaks through the traditional mindset of size and shape optimization, and demonstrates excellent global optimization capabilities and design freedom by intelligently seeking the optimal distribution of materials within a given design space. Among them, the SIMP (Solid Isotropic Material Penalty) model, as a mature implementation method, can generate optimized structures with clear boundaries and easy manufacturing, and has been successfully verified in cutting-edge fields such as aerospace.

[0027] This invention is based on advanced topology optimization theory and creatively incorporates the load characteristics of different platforms as key boundary conditions into the optimization model. Through reasonable design domain partitioning, clear objective function setting, and precise volume fraction control, this method can provide customized, high-performance lightweight solutions for thin-walled shells under different mechanical environments, thereby significantly improving the rationality of the structure and the overall operational efficiency of the output device.

[0028] This invention provides a lightweight design method for thin-walled shell structures based on topology optimization, such as... Figure 2 As shown, this lightweight design method includes: Step 1: Determine the thickness and length of the thin-walled shell based on the charge structure, and establish an initial model of the thin-walled shell.

[0029] Step two involves meshing the initial model with finite element elements (FEM) and using finite element software to simulate and analyze the structural strength under environmental load conditions. The stress, deformation, and modal characteristics of the initial model are then examined. Environmental load conditions can be impact loads or combinations of multiple load conditions.

[0030] Step 3: Perform topology optimization on the initial model using topology optimization software: Create a shell element mesh; apply material to the thin-walled shell, set boundary constraints and load conditions; divide the thin-walled shell into an optimized region L1 and a non-optimized region L2, such as... Figure 3As shown, the non-optimized region L2 is the critical area for load transfer and retains the original structure to ensure that the load-bearing path and connection function of the structure are not affected during the optimization process. The optimization region L1 is divided according to the shock wave propagation characteristics, the load application area, and the structural functional requirements. The boundary conditions of the optimization region L1 satisfy the following relationship:

[0031] In the above formula, C is the shock wave velocity, t is the time it takes for the shock wave to reach the top of the metal part at the output end, and D is the inner diameter of the thin-walled shell.

[0032] Set constraints and objective function: Use minimum flexibility as the response constraint to ensure structural stiffness; the optimization objective is lightweight thin-walled shell or stress homogenization, with a volume fraction of 0.3 set as the response; consider symmetry in the two-dimensional structure, adding symmetry constraints to the thin-walled shell; to avoid a "checkerboard" phenomenon in density distribution, set a minimum build-size constraint, which can be 3-5 times the average element size. Constraints can be stress constraints or displacement constraints.

[0033] Material distribution optimization is performed in the optimization region L1, while the material density remains unchanged in the non-optimization region L2, ensuring that critical functional areas are not affected by optimization.

[0034] Step four: Review the element density optimization results and perform configuration processing on the topology-optimized structure: Select a relative element density threshold and perform smoothing to obtain a two-dimensional planar model of the material density distribution, such as... Figure 4 As shown; contour features are extracted from the two-dimensional planar model, and then a three-dimensional model reconstruction design is performed, as follows. Figure 5 As shown, during the reconstruction process, sharp corners are rounded to reduce stress concentration, and material homogenization is performed at dimensional steps along the connection path to optimize structural rationality.

[0035] Step 5: Compare the quality differences before and after optimization and check the effect of lightweight design: Draw a finite element mesh for the topology-optimized 3D model, use the same constraints and load settings as the initial model, perform finite element verification analysis, analyze the differences in stress and deformation compared with the initial model, and ensure that the optimized structure has the initial structural strength and meets the allowable conditions.

[0036] Step six involves using finite element method (FEM) software to numerically simulate the high-speed motion body forming process of the topology-optimized lightweight thin-walled shell and the initial model. The impact of the topology-optimized structure on the output product is evaluated, and the velocity and aspect ratio of the moving body under the two structures (initial and optimized models) are compared and analyzed. Through comparison and verification, the optimized thin-walled shell achieves significant weight reduction while maintaining stability during high-speed motion body forming, and its performance is essentially consistent with the initial structure, verifying the effectiveness and engineering applicability of this method. Simulation verification tools can utilize other explicit dynamics modules or combine them with X-ray testing.

[0037] Compared with existing technologies that use lightweight material replacements, composite material splicing, or thin-walled shell reduction, the optimized method of this invention has the following advantages: 1. Maintain structural strength: The optimized thin-walled shell forms a skeletal load-bearing path, achieving a balance between lightweighting and strength maintenance, and avoiding the defect of "reducing weight means reducing strength".

[0038] 2. Eliminate interface problems: Use a single metal material design to avoid wave impedance differences and stress concentration caused by multi-material interfaces.

[0039] 3. Significant weight reduction: While maintaining output performance, the thin-walled shell achieves a weight reduction of nearly 50%. The reduction in weight improves the operational efficiency of the platform while maintaining the stability of high-speed flight body formation and the mechanical properties of the thin-walled shell.

[0040] 4. Complete and scalable: It proposes a system flow from topology optimization modeling to 3D reconstruction and simulation verification, which has good engineering feasibility and promotion value.

[0041] Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present invention without departing from the spirit and scope of the invention. Therefore, if these modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include these modifications and variations.

[0042] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A lightweight design method for thin-walled shell structures based on topology optimization, characterized in that, include: Step 1: Establish the initial model of the thin-walled shell; Step 2: Divide the initial model into finite element meshes and use finite element software to simulate the structural strength under environmental load conditions, and check the stress, deformation and modes of the initial model. Step 3: Use topology optimization software to perform topology optimization on the initial model; Step 4: Review the unit density optimization results and perform configuration processing on the topology-optimized structure; Step 5: Compare the quality differences before and after optimization to check the effect of the lightweight design; Step 6: Use finite element software to perform numerical simulation of the high-speed motion forming process of the topology-optimized lightweight thin-walled shell and the initial model, and evaluate the effect of the topology-optimized structure on the output product.

2. The lightweight design method for thin-walled shell structures based on topology optimization as described in claim 1, characterized in that, In step three, the initial model is topology optimized using topology optimization software, specifically including: Create a shell element mesh; Apply material to a thin-walled shell, and set boundary constraints and load conditions; The thin-walled shell is divided into an optimized region L1 and a non-optimized region L2. The non-optimized region L2 is the key area for load transfer and retains the original structure to ensure that the load-bearing path and connection function of the structure are not affected during the optimization process. Set constraints and objective function; Perform material distribution optimization within the optimization region L1.

3. The lightweight design method for thin-walled shell structures based on topology optimization as described in claim 2, characterized in that, In step three, the optimization region L1 is divided according to the shock wave propagation characteristics, the load application area, and the structural functional requirements. The boundary conditions of the optimization region L1 satisfy the following relationship: In the above formula, C For the shock wave velocity, t The time it takes for the shock wave to reach the top of the metal part at the output end. D This is the inner diameter of the thin-walled shell.

4. The lightweight design method for thin-walled shell structures based on topology optimization as described in claim 3, characterized in that, In step three, constraints and objective functions are set, specifically including: Minimum flexibility is used as the response constraint to ensure structural stiffness; The optimization objective is to reduce the weight of the thin-walled shell, and the volume fraction is set to 0.3 as the response. In a two-dimensional structure, symmetric constraints are added to the thin-walled shell; Set a minimum build size constraint to avoid the "checkerboard" phenomenon in density distribution.

5. The lightweight design method for thin-walled shell structures based on topology optimization as described in claim 4, characterized in that, The minimum build size constraint is 3-5 times the average cell size.

6. The lightweight design method for thin-walled shell structures based on topology optimization as described in any one of claims 1-5, characterized in that, Step four specifically includes: By selecting a relative unit density threshold and performing smoothing, a two-dimensional planar model of the material density distribution is obtained. Extracting contour features from a two-dimensional planar model; The three-dimensional model was reconstructed. During the reconstruction process, sharp corners were rounded to reduce stress concentration, and material homogenization was performed at dimensional steps on the connection path to optimize the structural rationality.

7. The lightweight design method for thin-walled shell structures based on topology optimization as described in claim 6, characterized in that, Step five specifically includes: Finite element meshing is performed on the topology-optimized 3D model; Using the same constraints and loads as the initial model, a finite element verification analysis was performed to analyze the differences in stress and deformation compared to the initial model, ensuring that the optimized structure has the initial structural strength and meets the allowable conditions.

8. The lightweight design method for thin-walled shell structures based on topology optimization as described in claim 7, characterized in that, Step six specifically includes: A comparative analysis was conducted on the velocity and aspect ratio of the moving body under the initial and optimized structures.

9. The lightweight design method for thin-walled shell structures based on topology optimization as described in claim 1, characterized in that, Before establishing the initial model of the thin-walled shell, the thickness and length of the thin-walled shell are determined based on the charge structure.

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