High-ductility thin-wall structure introduced with cutting seams and design optimization method of high-ductility thin-wall structure

Abstract

The invention discloses a cutting seam introduced high-ductility thin-wall structure and a design optimization method thereof, each basic unit in the thin-wall structure comprises a cutting strip and a blank-leaving strip, and the blank-leaving strip is arranged on the periphery of the cutting strip; transition zones are arranged between the longitudinal adjacent basic units, and cutting seams are arranged between the transverse adjacent basic units. The design optimization method comprises the following steps: S1, inputting expected structural elongation and an optimization target, and setting constraint conditions of geometric parameters and minimum machining precision required for manufacturing; s2, dividing parameter subspaces according to the array number of the basic units in the vertical direction; s3, performing correction iteration on an 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 an overall optimal geometric configuration. The structural ductility is improved, and the flexible thin-wall structure with the specific elongation can be customized according to requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of thin-wall structures, and in particular to a high-ductility thin-wall structure with a cutting seam introduced therein and a design optimization method thereof. Background Art

[0002] In the prior art, thin-walled structures are widely used in many fields such as construction engineering, aerospace, and electronic equipment. Thin-walled structures occupy an important position 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 when subjected to external stress, resulting in limited 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] In order to solve the problem of insufficient ductility of brittle materials, the prior art has proposed a variety of reinforcement methods. 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, which increases production costs and may also bring about material compatibility issues. In addition, although some existing design methods can improve the ductility of thin-walled structures to a certain extent, their effects are limited, and it is difficult to flexibly adjust structural parameters in different application scenarios to meet specific needs. In this context, how to effectively improve the ductility of thin-walled structures without increasing manufacturing difficulty and cost has become one of the hot topics in current research and engineering applications. Especially for those application fields that have special requirements for ductility, such as flexible expandable photovoltaics, building curtain walls, flexible electronics, etc., it is particularly important to develop a thin-walled structure that is both highly ductile and easy to industrialize. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a high-ductility thin-walled structure with a cutting seam and a design optimization method thereof, so as to prevent local fracture caused by excessive deformation of a single unit and improve the overall stability and reliability of the structure.

[0005] Technical solution: A highly ductile thin-walled structure with a cutting seam introduced, the thin-walled structure consisting of a clamping end and a plurality of basic units, each basic unit including a cutting strip and a blank strip, the cutting strip being surrounded by blank strips; a transition zone is provided between adjacent basic units in the longitudinal direction, and a cutting seam is provided between adjacent basic units in the transverse direction.

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

[0007] Furthermore, the cutting slits are adjusted according to actual application requirements and do not need to be evenly arranged in the same row of basic units.

[0008] Any of the above-mentioned methods for designing and optimizing a high-ductility thin-walled structure comprises the following steps:

[0009] S1, input the desired structural elongation Δλ and optimization target G, and set the constraints of the geometric parameters and the minimum processing accuracy required for manufacturing;

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

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

[0012] S4, in different parameter subspaces, the interior point method is used to refine the initial configuration and optimize the design, and the boundary domain of the parameter space is checked to 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] Furthermore, the improvement value Δλ of the high ductility thin-walled structure on the elongation at break of the material is calculated by the following formula:

[0015]

[0016] Among them, n y is the number of basic units in the vertical array;

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

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

[0019] The optimization goal G includes minimizing the amount of material used, improving mechanical properties, or optimizing functions in specific application scenarios; the optimization goal G is based on the cutting parameters (n x ,n y ,l1,l2,w1,w2) is the function expression of the variable, where n x is the number of basic units in the horizontal direction; the optimization problem is expressed as:

[0020]

[0021] Among them, E is the expected value; ε is the minimum machining accuracy; lb1, lb2, lb3 are the upper limits of the values; ub1, ub2, ub3 are the upper limits of the values, Expressed 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 independently run multiple times in each parameter subspace to generate multiple initial results, all the 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 cutting seams in thin-walled structures without changing the properties of the material itself. The geometric design of the cutting seams enables the structure to effectively absorb and disperse stress when subjected to force, using a unique deformation method to avoid brittle fracture caused by stress concentration, thereby significantly improving the overall ductility of the material;

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

[0029] 3. Flexible customized design: The present invention introduces a systematic design optimization method, which can flexibly adjust geometric parameters according to different application requirements, thereby realizing customized design of flexible thin-walled structures with specific elongation. This optimization method can not only meet the needs of various application scenarios, but also ensure that the designed structure achieves the best balance between performance and manufacturing feasibility;

[0030] 4. Improve design efficiency: The present invention can effectively solve the optimization difficulties caused by discrete parameters by combining parameter space division and optimization algorithm, thereby improving design efficiency and optimization effect. Multiple runs of probability-based optimization algorithms 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 manufacturing and low cost: The thin-walled structure of the present invention 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 invention highly feasible for industrial production and can be promoted on a large scale in practical applications;

[0032] 7. Broad engineering application prospects: The high-ductility thin-walled structure of the present invention is also suitable for brittle materials. These brittle materials are usually limited in application under high-strain environments. The present invention improves the ductility of these brittle materials and broadens their application scope in the fields of building curtain walls, flexible photovoltaics, flexible electronics, wearable medical devices, etc., and has good engineering application prospects and market potential. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0034] Figure 2 A flow chart of the optimization method for designing the present invention;

[0035] Figure 3 Schematic diagram of Example 1 of the present invention, wherein (a) is an uncut stainless steel sheet, (b) is a structure after cutting, (c) is a deformed front view of the final stretched state, and (d) is a right oblique view of the final stretched state;

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

[0037] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0038] The present invention introduces a cutting seam method to propose a highly ductile thin-walled structure, which can significantly improve the ductility of the structure without changing the material's own properties; and provides a process for quantitatively designing and optimizing the ductility of the structure. The present invention opens up new possibilities for the application of traditional thin-walled structures in high-strain fields, is applicable to a variety of materials, is simple to manufacture, and has broad engineering application prospects.

[0039] like Figure 1 The present invention shows a highly ductile thin-walled structure. The present invention significantly improves the ductility of the material by introducing specific cutting strips 20 and cutting seams 3 into the thin-walled structure, and provides an optimization process for flexibly adjusting geometric parameters to meet the needs of different application scenarios. The following is a specific implementation of the present invention.

[0040] Structural design: The thin-walled structure of the present invention is composed of basic units 2 with repetitive characteristics. Each cutting strip 20 has a length of l1 and a width of w1, and the ends of all cutting strips 20 are designed as a semicircular structure 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 adjacent basic units in the longitudinal direction is 2l2. The specific size of the clamping end 1 can be adjusted according to actual application requirements. The thin-walled structure of the present invention 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 adjacent basic units 2 in the horizontal direction. 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 evenly arranged in the same row of basic units 2, and it is not necessary to introduce vertical cutting seams 3 between adjacent basic units 2 in the horizontal direction. They can be adjusted according to actual application requirements, and only consistency needs to be maintained between adjacent basic units 2 in the vertical direction. In addition, the corners of the cutting seams 3 are designed in an arc shape to reduce stress concentration problems, thereby effectively preventing local fractures and further extending the fatigue life of the structure.

[0042] Manufacturing process: The thin-walled structure of the present invention can be processed by conventional processes such as laser cutting, water jet cutting or chemical etching on flat plates and membranes. These processing methods are not only simple to operate, but also low in cost and suitable for large-scale industrial production.

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

[0044]

[0045] Among them, n y is the number of basic units in the vertical array, that is, the number of units in the same column;

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

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

[0048] like Figure 2 Shown is a flow chart of a design optimization method for a high ductility thin-walled structure, the optimization method comprising the following steps:

[0049] Step 1: Input the desired structural elongation Δλ and optimization target G, and set the constraints of the geometric parameters and the minimum processing accuracy required for manufacturing;

[0050] The optimization target G may include but is not limited to minimizing the amount of material used, improving mechanical properties (such as overall stiffness), or optimizing functions in specific application scenarios. It is worth noting that the optimization target G needs to be based on the cutting parameters (n x ,n y ,l1,l2,w1,w2) are function expressions of variables, and new variables cannot be introduced. x is the number of arrays of basic units in the horizontal direction, that is, the number of units in the same row. Since the optimization design process of the present invention is applicable to all optimization targets with such characteristics, and there are a large number of optimization targets that meet this condition, the optimization targets will not be described in detail. In addition, it is necessary to set the constraints of the geometric parameters according to the actual application requirements to ensure that the designed structure strikes a balance between performance and manufacturing feasibility. At the same time, it is also necessary to input the minimum processing accuracy required in the manufacturing process. The minimum processing accuracy should be set according to the selected manufacturing method and the capacity of the equipment used to ensure that the final structure can achieve the expected accuracy and quality requirements during the manufacturing process.

[0051] This type of optimization problem can be expressed as

[0052]

[0053] Where E is the expected value; ε is the minimum machining accuracy; lb1, lb2, lb3 are the upper limits; ub1, ub2, ub3 are the upper limits, Expressed as a real number, Represents a positive integer.

[0054] Step 2: According to n y The value range of is divided into parameter space;

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

[0056]

[0057] Since the parameter n y is a positive integer with discrete values, so its value range can be divided into multiple subspaces, and n y Treat n as a constant to avoid discontinuity problems. 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. In the divided parameter subspace, n yConverted into a constant, thus effectively avoiding the y This method allows for more accurate optimization in each parameter subspace and ensures the continuity and stability of the optimization process.

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

[0059] Step 4: In each parameter subspace, use the optimal value in step 3 as the initial point and use the interior point method to perform refined parameter optimization on the initial configuration. 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 present invention is further described below in conjunction with specific embodiments and with reference to the accompanying drawings. Embodiment 1 and Embodiment 2 both use stainless steel 304 as the material for the experiments. It is worth noting that the present invention is not only applicable to stainless steel 304, but can also be widely applied to a variety of materials, including but not limited to metal materials, inorganic non-metallic materials and composite materials. The selection of stainless steel 304 as the material of the embodiment is only to illustrate the application effect of the present invention in detail, and does not constitute a limitation of the present invention.

[0062] Example 1

[0063] The present invention aims to demonstrate the effect of the structure of the present invention on improving 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, set the basic unit geometry parameters to: 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 116 mm in length and 9 mm in width for fixation and loading.

[0066] Step 3: Fix one end of the sheet and apply vertical tensile force to the other end to test the ductility of the structure. This example uses finite element simulation to show the behavior of the structure during the stretching process. Figure 3 shown.

[0067] Finite element analysis results show that the elongation at break of a conventional stainless steel 304 thin-walled structure without cutting is usually less than 25%. However, by introducing a specific geometric cutting seam into the thin-walled structure, the elongation at break is significantly increased 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 invention has a significant effect in improving the ductility of materials and has broad engineering application prospects.

[0068] Example 2

[0069] Embodiment 2 of the present invention realizes the reverse optimization design of the structure by adopting the design optimization framework. The specific goal is that the expected value E of Δλ is 120%, and the material usage is minimized (without considering the clamping end). Therefore, the optimization target G of this goal is the material usage, which can be expressed by the following formula:

[0070]

[0071] The optimization problem can be described as:

[0072]

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

[0074] Step B1, initial setting;

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

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

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

[0078] n x =4, that is, the number of units arranged horizontally is 4 rows.

[0079] Step B2, parameter space division;

[0080] Furthermore, according to n y The value range of , divides the parameter space into 9 subspaces. In each subspace, n y As a constant, corresponding to n y Equals 2, 3, 4, 5, 6, 7, 8, 9, 10.

[0081] Step B3, generating an initial configuration;

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

[0083] Step B4, parameter optimization;

[0084] Furthermore, the initial parameters determined in step B3 are refined by using the interior point method for parameter optimization. During the optimization process, the boundaries of the definition domain of the parameter subspace must also be strictly checked to ensure that the values ​​on the boundaries are not ignored. Specifically, the optimal value on the boundary of the definition domain is compared with the internal optimal solution obtained by the interior point method to determine the optimal configuration in 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. This example uses stainless steel 304 as the material, and uses finite element simulation to show the behavior of the structure during the stretching process, such as Figure 4 The elongation at break of the final structure is 154.2%. Compared with the original elongation at break of the stainless steel material (about 25%), the elongation of the final structure is increased by about 129.2%, and the error with the expected value is only 8.3%. Considering that there are often certain errors in finite element simulation, this result is acceptable and shows 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 solution of the present invention, and 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, a person of ordinary skill in the art can also make many forms of specific changes under the guidance of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. A highly ductile thin-walled structure with a cutting seam introduced, 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) comprising a cutting strip (20) and a blank strip (21), the cutting strip (20) being 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 introduced according to claim 1, characterized in that: The end of the cutting strip (20) is a semicircular structure. Assuming that the length of the cutting strip (20) is l1 and the width is w1, and the distance from the end of the cutting strip (20) to the end of the basic unit (2) is l2, the length of the blank strip (21) is l1+2l2+w1, and the length of the transition zone is 2l2.

3. The high ductility thin-walled structure with a cutting seam introduced 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 include: S1, input the desired structural elongation Δλ and optimization target G, and set the constraints of the geometric parameters and the minimum processing accuracy required for manufacturing; S2, divide the parameter subspace according to the number of basic units in the vertical direction; S3, iterate and modify the initial result 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, and 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 of the high ductility thin-walled structure according to claim 4, characterized in that: The improvement value Δλ of the elongation at break of the material due to the high ductility thin-walled structure is calculated by the following formula: Among them, n y is the number of basic units in the vertical array; X = (0.5l1-l2) / (2w2+w1), which is a dimensionless number; l1, l2, w1, w2 are the geometric parameters used for cutting; The optimization goal G includes minimizing the amount of material used, improving mechanical properties, or optimizing functions in specific application scenarios; the optimization goal G is based on the cutting parameters (n x ,n y ,l1,l2,w1,w2) is the function expression of the variable, where n x is the number of basic units in the horizontal direction; the optimization problem is expressed as: Among them, E is the expected value; ε is the minimum machining accuracy; lb1, lb2, lb3 are the upper limits of the values; ub1, ub2, ub3 are the upper limits of the values, Expressed as a real number, Represents a positive integer.

6. The design optimization method of the high ductility thin-walled structure according to claim 5, characterized in that: n y The value range of is expressed as: 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 of 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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