A high ductility thin-walled structure with a cut slit and a design optimization method thereof

Abstract

The application discloses a high-ductility thin-wall structure with a cutting seam and a design optimization method thereof. Each basic unit of the thin-wall structure comprises a cutting strip and a blank strip, and the cutting strip is surrounded by the blank strip. A transition zone is arranged between longitudinally adjacent basic units, and a cutting seam is arranged between transversely adjacent basic units. The design optimization method comprises the following steps: S1, inputting a desired structure elongation and an optimization target, and setting a constraint condition of a geometric parameter and a minimum machining precision required for production; S2, dividing a parameter subspace according to the array number of the basic unit in the vertical direction; S3, correcting and iterating the initial result in the parameter subspace, and selecting an optimal value as an initial configuration; S4, solving the optimal configuration in the local parameter space in different parameter subspaces; and S5, solving the overall optimal geometric configuration. The application improves the structure ductility and can customize a flexible thin-wall structure with a specific elongation according to requirements.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thin-walled structures, in particular to a high-ductility thin-walled structure with cutting joints and a design optimization method thereof. BACKGROUND

[0002] In the prior art, thin-walled structures are widely used in various fields such as construction engineering, aerospace, electronic equipment, etc. Thin-walled structures play an important role in various industrial applications due to their light weight and high material utilization. However, traditional thin-walled structures are usually made of low-ductility materials, which are prone to fracture under external stress, limiting their ductility. This brittle fracture not only limits the application of thin-walled structures in certain high-strain environments, but also increases the complexity of design and manufacturing.

[0003] To solve the problem of insufficient ductility of brittle materials, various enhancement methods have been proposed in the prior art. For example, composite materials are used instead of single materials to improve the ductility and toughness of the structure. However, these methods usually require complex manufacturing processes, increasing production costs and possibly causing material compatibility problems. In addition, some existing design methods can improve the ductility of thin-walled structures to a certain extent, but their effectiveness is limited, and it is difficult to flexibly adjust the structure parameters to meet specific requirements in different application scenarios. In this context, how to effectively improve the ductility of thin-walled structures without increasing manufacturing difficulty and cost has become one of the hotspots in current research and engineering applications. Especially for application fields with special requirements for ductility, such as flexible deployable photovoltaics, building curtain walls, flexible electronics, etc., it is particularly important to develop a thin-walled structure with high ductility and easy industrial production. SUMMARY

[0004] The purpose of the present application is to provide a high-ductility thin-walled structure with cutting joints and a design optimization method thereof, which can prevent local fracture caused by excessive deformation of single units and improve the overall stability and reliability of the structure.

[0005] Technical solution: A high-ductility thin-walled structure with cutting joints, the thin-walled structure is composed of a clamping end and a plurality of basic units, each basic unit includes a cutting strip and a blank strip, the cutting strip is surrounded by the blank strip; a transition zone is provided between longitudinally adjacent basic units, and a cutting joint is provided between transversely adjacent basic units.

[0006] Further, the end of the cutting strip is a semicircular structure, the length of the cutting strip is l1, the width is w1, the distance from the end of the cutting strip to the end of the basic unit is l2, then the length of the blank strip is l1+2l2+w1, and the length of the transition zone is 2l2.

[0007] Further, the cutting seam is adjusted according to actual application requirements, and does not need to be uniformly arranged in the same row of basic units.

[0008] The design optimization method of any one of the high-ductility thin-walled structures includes the following steps:

[0009] S1, input the desired structure elongation Δλ and optimization target G, and set the constraint conditions of geometric parameters and the minimum machining precision required for production;

[0010] S2, according to the array number of the basic unit in the vertical direction, divide the parameter subspace;

[0011] S3, correct and iterate the initial result in the parameter subspace, and select the optimal value as the initial configuration;

[0012] S4, in different parameter subspaces, use the interior point method to perform fine optimization design on the initial configuration, check the boundary domain of the parameter space, and solve the optimal configuration in the local parameter space;

[0013] S5, compare the local optimal solutions in different parameter spaces, and solve the overall optimal geometric configuration.

[0014] Further, the improvement value Δλ of the material fracture elongation of the high-ductility thin-walled structure is calculated by the following formula:

[0015]

[0016] Wherein, n y is the array number of the basic unit in the vertical direction;

[0017] X=(0.5l1-l2) / (2w2+w1) is a dimensionless number;

[0018] l1, l2, w1, w2 are geometric parameters for cutting;

[0019] The optimization target G includes minimization of material usage, improvement of mechanical properties, or functional optimization in specific application scenarios; the optimization target G is a function expression with the cutting parameters (n x , n y , l1, l2, w1, w2) as variables, wherein n x is the array number of the basic unit in the horizontal direction; and the optimization problem is represented as:

[0020]

[0021] Wherein, E is the expected value; ε is the minimum machining precision; lb1, lb2, lb3 are upper bounds; ub1, ub2, ub3 are upper bounds, represented as a real number, Represents a positive integer.

[0022] Further, y The value range of is expressed as:

[0023]

[0024] n y The value range is divided into parameter subspaces, where is less than or equal to n y The maximum integer value, is greater than or equal to n y The minimum integer value.

[0025] Furthermore, in step S3, the probability-based optimization algorithm is run independently multiple times in each parameter subspace to generate multiple initial results. All initial results are compared and analyzed, and the optimal value is selected as the initial configuration for further refined optimization.

[0026] Compared with the prior art, the present invention has the following significant effects:

[0027] 1. Improved ductility: This invention significantly improves the ductility of traditional low-ductility materials by introducing periodic cuts into thin-walled structures without changing the inherent properties of the material. The geometric design of the cuts allows the structure to effectively absorb and disperse stress through a unique deformation mode when subjected to stress, avoiding brittle fracture caused by stress concentration, thereby significantly improving the overall ductility of the material.

[0028] 2. Uniform deformation and stability: The design of cut seams between adjacent units in the horizontal direction significantly reduces the necking phenomenon of the structure during deformation, ensuring uniform deformation of the structure under stress. This structural design effectively prevents local fracture caused by excessive deformation of a single unit, and improves the overall stability and reliability of the structure.

[0029] 3. Flexible Customized Design: This invention introduces a systematic design optimization method that allows for flexible adjustment of geometric parameters based on different application requirements, thereby enabling customized design of flexible thin-walled structures with specific elongation rates. This optimization method not only adapts to the needs of various application scenarios but also ensures that the designed structure achieves an optimal balance between performance and manufacturability.

[0030] 4. Improved design efficiency: By combining parameter space partitioning with optimization algorithms, this invention can effectively resolve the optimization difficulties caused by discrete parameters, thereby improving design efficiency and optimization results. Repeatedly running the probability-based optimization algorithm combined with derivative-based refined optimization can increase the probability of finding the global optimal configuration, thereby providing a more optimized structural design solution for practical applications.

[0031] 6. Easy to manufacture and low cost: The thin-walled structure of the present application can be manufactured in a two-dimensional plane by conventional processing techniques such as laser cutting, water cutting or chemical etching. These process methods are easy to operate and low in cost, making the present application have high industrial production feasibility, and can be widely promoted in practical applications;

[0032] 7. Wide engineering application prospect: The high ductility thin-walled structure of the present application is also suitable for brittle materials, which are usually limited in high strain environment. The present application improves the ductility of these brittle materials, broadens their application range in building curtain wall, flexible photovoltaic, flexible electronics, wearable medical devices and other fields, and has good engineering application prospect and market potential. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a schematic diagram of the thin-walled structure of the present application;

[0034] Figure 2 is a flowchart of the design optimization method of the present application;

[0035] Figure 3 is a schematic diagram of Example 1 of the present application, wherein (a) is a stainless steel sheet without cutting, (b) is the structure after cutting, (c) is a deformation front view of the final state of stretching, and (d) is a right oblique view of the final state of stretching.

[0036] Figure 4 is a schematic diagram of Example 2 of the present application, wherein (a) is a deformation front view of the final state of stretching, and (b) is a right oblique view of the final state of stretching. DETAILED DESCRIPTION

[0037] The present application will be further described in detail below in conjunction with the drawings and specific embodiments of the present application.

[0038] The present application proposes a high-ductility thin-walled structure by introducing a cutting seam, which can significantly improve the ductility of the structure without changing the properties of the material itself. The present application provides a process for quantitatively designing and optimizing the ductility of the structure. The present application opens up new possibilities for the application of traditional thin-walled structures in the high strain field, is suitable for a variety of materials, and is easy to manufacture, and has a wide engineering application prospect.

[0039] As shown in Figure 1 The present application introduces specific cutting strips 20 and cutting seams 3 into the thin-walled structure to significantly improve the ductility of the material, and provides an optimization process for flexibly adjusting the geometric parameters to meet the needs of different application scenarios. The following is a specific embodiment of the present application.

[0040] Structure design: The thin-walled structure of the present application is composed of basic units 2 with repetitive features. Each cut strip 20 has a length of l1 and a width of w1, and the ends of all cut strips 20 are designed as semicircular structures with a diameter of w1. The length of the blank strip 21 is (l1+2l2+w1), and the width is w2. The length of the transition zone between longitudinally adjacent basic units is 2l2. The specific size of the clamping end 1 can be adjusted according to the actual application requirements. The thin-walled structure of the present application is suitable for a variety of materials, including but not limited to metal materials, inorganic non-metallic materials, organic polymer materials, and composite materials.

[0041] Cutting seam design: In order to improve the uniform deformation performance of the structure, cutting seams 3 are introduced between transversely adjacent basic units 2. These cutting seams significantly reduce the necking phenomenon of the structure during deformation, making the deformation between different basic units 2 more uniform, thereby reducing the risk of fracture caused by excessive deformation of a single basic unit 2. It is worth noting that the vertical cutting seams 3 do not need to be uniformly arranged in the same row of basic units 2, and the vertical cutting seams 3 do not necessarily need to be introduced between transversely adjacent basic units 2. They can be adjusted according to actual application requirements, as long as consistency is maintained between longitudinally adjacent basic units 2. In addition, the corners of the cutting seams 3 are designed with a circular arc shape to reduce stress concentration problems, thereby effectively preventing local fracture and further extending the fatigue life of the structure.

[0042] Manufacturing process: The thin-walled structure of the present application can be processed by laser cutting, water cutting or chemical etching on flat panel materials or film materials. These processing methods are not only simple to operate, but also low in cost, suitable for large-scale industrial production.

[0043] Further, the improvement value Δλ of the material elongation at break of such a structure can be approximately calculated by the following formula:

[0044]

[0045] wherein n y is the number of basic units in the vertical direction, i.e. the number of units in the same column;

[0046] X = (0.5l1-l2) / (2w2+w1) is a dimensionless number;

[0047] l1, l2, w1, w2 are the geometric parameters for cutting.

[0048] As Figure 2 shown in the flowchart of the design optimization method of the high-ductility thin-walled structure, the optimization method comprises the following steps:

[0049] Step 1, input the desired structure elongation Δλ and optimization target G, and set the constraint conditions of the geometric parameters and the minimum processing accuracy required for production;

[0050] The optimization target G can include, but is not limited to, minimization of material usage, improvement of mechanical properties (such as overall stiffness), or functional optimization in specific application scenarios, etc. It is worth noting that the optimization target G needs to be a function expression with the cutting parameters (n x ,n y ,l1,l2,w1,w2) as variables, and cannot introduce new variables, where n x is the array number of the basic unit in the horizontal direction, that is, the number of units in the same row. Since the optimization design process of the present application is applicable to all optimization targets with such characteristics, the number of optimization targets meeting this condition is numerous, and therefore the optimization target is not described in detail. In addition, according to the actual application requirements, the constraint conditions of the geometric parameters need to be set to ensure a balance between the performance and manufacturing feasibility of the designed structure. At the same time, the minimum machining precision required in the manufacturing process needs to be input, which should be set according to the selected manufacturing method and the equipment capacity used, to ensure that the final structure can achieve the expected precision and quality requirements in the manufacturing process.

[0051] Such an optimization problem can be expressed as

[0052]

[0053] where E is the expected value; ε is the minimum machining precision; lb1, lb2, lb3 are upper bounds of values; ub1, ub2, ub3 are upper bounds of values, is expressed as a real number, is expressed as a positive integer.

[0054] Step 2, according to the value range of n y , divide the parameter space;

[0055] The value range of n y can be expressed as:

[0056]

[0057] Since the parameter n y is a positive integer, its value is discrete, so its value range can be divided into multiple subspaces. In each subspace, n y is considered as a constant to avoid discontinuity problems. The value range of n y is divided into parameter subspaces, where is an integer less than or equal to the maximum value of n y , and is an integer greater than or equal to the minimum value of n y . In the divided parameter subspaces, n ytransformed into constants, thus effectively avoiding optimization difficulties caused by discontinuity of n y This method allows more accurate optimization within each parameter subspace and ensures continuity and stability of the optimization process.

[0058] Step 3, within each parameter subspace, run the optimization algorithm based on probability properties (such as simulated annealing algorithm, particle swarm algorithm) multiple times independently to generate multiple initial results, compare all initial results, and select the optimal value as the initial configuration for further fine-tuning optimization. This method can increase the probability of finding the global optimal configuration.

[0059] Step 4, within each parameter subspace, use the interior point method to fine-tune the parameter optimization of the initial configuration with the optimal value in step 3 as the initial point. Check the subspace boundary conditions and solve the local optimal configuration. Specifically, compare the optimal value on the subspace value boundary domain with the optimal solution inside the subspace obtained by the interior point method, and select the optimal result as the optimal solution in the subspace.

[0060] Step 5, compare the optimal solutions in different parameter subspaces and select the overall optimal geometric configuration.

[0061] The application will be further described below in conjunction with specific examples and with reference to the accompanying drawings. Both Example 1 and Example 2 use stainless steel 304 as the material for the experiment. It is worth noting that the application is not only applicable to stainless steel 304, but can also be widely applied to various materials, including but not limited to metal materials, inorganic non-metallic materials, and composite materials. The selection of stainless steel 304 as the material for the examples is only to illustrate the application effect of the application, and does not constitute a limitation on the application.

[0062] Example 1

[0063] The application aims to demonstrate the improvement effect of the structure of the application on the ductility of the material through Example 1. The material of this example is stainless steel 304, and the specific steps are as follows:

[0064] Step 1, select a stainless steel sheet with a thickness of 1 mm, a length of 120 mm, and a width of 90 mm as the experimental material.

[0065] Step 2, cut the stainless steel sheet, and set the basic unit geometric parameters as follows: l1 = 20 mm, l2 = 3.5 mm, w1 = 2 mm, w2 = 5 mm, and arrange 4 columns and 5 rows of basic units on the sheet. In addition, the geometric dimensions of the clamping end are set to a length of 116 mm and a width of 9 mm to facilitate fixation and loading.

[0066] Step three, one end of the sheet is clamped and fixed, and the other end is subjected to a vertical tensile force to test the ductility of the structure. This example uses finite element simulation to show the behavior of the structure during stretching, as shown in Figure 3

[0067] The finite element analysis results show that the elongation at break of the traditional stainless steel 304 thin-walled structure without cutting is usually less than 25%. However, by introducing specific geometric cutting slots in the thin-walled structure, the elongation at break is significantly improved to 120.4%, which is about 3.8 times higher than the original material. This result shows that the structural design method of the present application has a significant effect on improving the ductility of the material and has a wide engineering application prospect.

[0068] Example 2

[0069] Example 2 of the present application realizes reverse optimization design of the structure by using a design optimization framework. The specific goal is that the expected value E of Δλ is 120%, and the material usage is minimized (not considering the clamped end), so the optimization goal G of this goal is the material usage, which can be expressed as:

[0070]

[0071] Then the optimization problem can be described as:

[0072]

[0073] The following are the specific steps of this example 2:

[0074] Step B1, initial setting;

[0075] n y must be in the range of 2 to 10;

[0076] w1 and w2 must be in the range of 2mm to 10mm;

[0077] l1 and l2 must be in the range of 2mm to 30mm;

[0078] n x = 4, i.e. the number of transversely arranged units is 4 columns.

[0079] Step B2, parameter space division;

[0080] Further, according to the value range of n y , the parameter space is divided into 9 subspaces. In each subspace, n y is a constant value, corresponding to n y equal to 2, 3, 4, 5, 6, 7, 8, 9, 10 in turn.

[0081] Step B3, generate initial configuration;​

[0082] Furthermore, in each parameter subspace, the simulated annealing algorithm is used five times to generate five sets of initial parameters (increasing the number of initial parameters helps to improve the optimization effect). Finally, all parameter combinations are compared and analyzed, and the most reasonable ones are selected as the initial parameters for further optimization.

[0083] Step B4, parameter optimization;

[0084] Furthermore, the initial parameters determined in step B3 are refined using the interior point method for parameter optimization. During the optimization process, the boundaries of the domain of the parameter subspace must be rigorously checked to ensure that values ​​on the boundaries are not ignored. Specifically, the optimal value at the domain boundary is compared with the internal optimal solution obtained using the interior point method to determine the optimal configuration within the parameter subspace.

[0085] Step B5, overall optimization;

[0086] Furthermore, after completing the local optimization of each parameter subspace, the local optimal solutions in different parameter subspaces are compared to select the overall optimal geometric configuration.

[0087] Through the above analysis process, the geometric parameters of the optimal configuration are finally determined to be w1=w2=l2=2mm, n=5, l1=20mm. In this example, stainless steel 304 is selected as the material, and finite element simulation is used to demonstrate the behavior of the structure during the stretching process, such as Figure 4 The final structure achieved an elongation at break of 154.2%. Compared to the original elongation at break of the stainless steel material (approximately 25%), the elongation of the final structure increased by approximately 129.2%, with an error of only 8.3% from the expected value. Considering that finite element simulations often have certain errors, this result is acceptable and demonstrates that the design optimization framework of the present invention has high accuracy and feasibility in practical applications.

[0088] Finally, it should be noted that the present invention is not limited to the embodiments described above. The above description of the specific embodiments is intended to describe and illustrate the technical solutions of the present invention. The above specific embodiments are merely illustrative and not restrictive. Without departing from the scope of the present invention and the scope of protection of the claims, those skilled in the art may make various specific modifications based on the teachings of the present invention, all of which fall within the scope of protection of the present invention.

Claims

1. A high-ductility thin-walled structure with a cutting seam, characterized in that: The thin-walled structure is composed of a clamping end (1) and a plurality of basic units (2), each basic unit (2) including a cutting strip (20) and a blank strip (21), and the cutting strip (20) is surrounded by blank strips (21); a transition zone is provided between adjacent basic units (2) in the longitudinal direction, and a cutting seam (3) is provided between adjacent basic units (2) in the transverse direction.

2. The high-ductility thin-walled structure with a cutting seam according to claim 1, characterized in that: The end of the cutting strip (20) is a semicircular structure. The length of the cutting strip (20) is l 1. Width is w 1. The distance from the end of the cutting strip (20) to the end of the basic unit (2) is l 2, then the length of the blank strip (21) is l 1+2 l 2+ w 1, the transition zone length is 2 l 2.

3. The high-ductility thin-walled structure with a cutting seam according to claim 1, characterized in that: The cutting slits (3) are adjusted according to actual application requirements and do not need to be evenly arranged in the same row of basic units.

4. The design optimization method for a high ductility thin-walled structure according to any one of claims 1 to 3, characterized in that: The steps are as follows: S1, input the desired structural elongation and optimization goals G , and set the constraints of geometric parameters and the minimum processing accuracy required for production; S2, divide the parameter subspace according to the number of basic units in the vertical direction; S3, iterate and modify the initial results in the parameter subspace and select the optimal value as the initial configuration; S4, in different parameter subspaces, the interior point method is used to refine the initial configuration and optimize the design. The boundary domain of the parameter space is checked to solve the optimal configuration in the local parameter space. S5, compare the local optimal solutions in different parameter spaces and solve the overall optimal geometric configuration.

5. The design optimization method for a high-ductility thin-walled structure according to claim 4, characterized in that: The high ductility thin-walled structure improves the elongation at break of the material Calculated by the following formula: ， in, n y is the number of basic units in the vertical array; , is a dimensionless number; l 1. w 1 are the length and width of the cutting strip (20) respectively; l 2 is the distance from the end of the cutting strip (20) to the end of the basic unit (2); w 2 is the width of the blank strip (21); the optimization goal G Including minimization of material usage, improvement of mechanical properties, or functional optimization in specific application scenarios; optimization goals G The cutting parameters ( n x , n y , l 1, l 2 , w 1, w 2) is a function expression of variables, where n x is the number of basic units in the horizontal array; the optimization problem is expressed as: ， in, E is the expected value; ε is the minimum machining accuracy; lb 1, lb 2, lb 3 is the upper bound of the value; ub 1, ub 2, ub 3 is the upper bound of the value, Expressed as a real number, Represents a positive integer.

6. The design optimization method for a high-ductility thin-walled structure according to claim 5, characterized in that: n y The value range of is expressed as: ， Will n y The value range is divided into parameter subspaces, where is less than or equal to n y The maximum integer value, is greater than or equal to n y The minimum integer value.

7. The design optimization method for a high-ductility thin-walled structure according to claim 4, characterized in that: In step S3, the probability-based optimization algorithm is run independently multiple times in each parameter subspace to generate multiple initial results. All initial results are compared and analyzed, and the optimal value is selected as the initial configuration for further refined optimization.

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