Storage box structure optimization design method and system based on rotational symmetry model

Abstract

According to the storage tank structure optimization design method and system based on the rotational symmetry model, the mechanical characteristic that the storage tank structure is rotationally symmetrical in the circumferential direction is utilized, the local model of the storage tank is established, and the speed of solving the bearing capacity through finite elements is greatly increased. On the basis, by building a storage tank structure parameter optimization process of parametric modeling, calculation, result extraction and parameter optimization, the storage tank design efficiency is greatly improved, the period of one to two months required by a traditional storage tank design method is shortened to one to two days, a fundamental breakthrough of obtaining an excellent design scheme within extremely short time is achieved, and the method is suitable for large-scale popularization and application. The method has great value for improving the rapid research and development and advanced manufacturing capability of aerospace equipment.

Description

Technical Field

[0001] This invention relates to the field of launch vehicle propellant tank design technology, and in particular to a propellant tank structure optimization design method and system based on a rotationally symmetric model. Background Technology

[0002] The propellant tank is a core component of the launch vehicle's structure, accounting for a significant proportion of the overall rocket's mass. Therefore, effectively optimizing the propellant tank design to reduce its structural mass is one of the key means to improve the rocket's structural efficiency and payload capacity.

[0003] Existing tank design methods primarily rely on design experience, theoretical calculations, and finite element method (FEM) verification. First, relatively reasonable parameter design values ​​are derived based on design experience. Then, theoretical calculations verify whether the design specifications are met. Next, a finite element model is established for verification. Parameters are adjusted based on the verification results, and this process is repeated iteratively until the structural dimensions are finally determined. This design method suffers from the following problems: 1. Over-reliance on design experience can lead to significant initial design deviations, resulting in excessive iterations and low efficiency. 2. Establishing a full-tank 3D finite element model is extremely large, especially with the increasing size of modern rockets. A single calculation on a standard computer can take 1-3 days, and the entire design process typically lasts from one week to one month. 3. After obtaining structural parameters that meet design requirements, it is difficult to intuitively assess structural efficiency and further optimize the design, hindering in-depth optimization work such as weight reduction.

[0004] Existing tank design methods have significant bottlenecks in terms of efficiency, cost, and optimization capabilities. Therefore, there is an urgent need to provide a new method that can significantly improve design efficiency, reduce computational costs, and achieve automatic optimization design. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a tank structure optimization design method and system based on a rotationally symmetric model, achieving a fundamental breakthrough in obtaining an optimal design scheme in a very short time, which is of great value for improving the rapid research and development and advanced manufacturing capabilities of aerospace equipment.

[0006] This invention provides a method for optimizing the design of a storage tank structure based on a rotationally symmetric model, comprising at least the following steps:

[0007] Step 1: Determine the fixed dimensional parameters and the dimensional parameters to be optimized for the tank structure, and set at least the upper and lower limits of the dimensional parameters to be optimized based on the process and raw material characteristics.

[0008] Step 2: Determine the material parameters of the storage tank structure;

[0009] Step 3: Determine the load conditions that the tank structure needs to meet;

[0010] Step 4: Using the finite element software Abaqus, combined with the fixed dimension parameters, the dimension parameters to be optimized, the material parameters, and the load conditions, establish a rotationally symmetric model including the local skin, stringers, and ring frame, divide the finite element mesh, apply loads, and add rotationally symmetric boundary conditions.

[0011] Step 5: Use the ISight optimization software to drive the finite element software Abaqus to solve the rotationally symmetric model, and extract the calculation results of the mass, Mises stress and bearing capacity of the overall tank structure from the calculation results;

[0012] Step 6: With the goal of minimizing the overall structural mass of the storage tank, and with the Mises stress and the load-bearing capacity satisfying the load conditions as optimization constraints, iterative optimization is performed using the ISight optimization software until the optimal lightweight design scheme that satisfies all constraints is obtained.

[0013] Furthermore, the fixed dimensional parameters include the tank radius r and the tank axial height l; the dimensional parameters to be optimized include the skin thickness t_sk and the thickness of each stringer plate t_st. i And the thickness of the ring frame t_rf, the width of each plate of the stringer h_st i The width h_rf of each plate in the ring frame i The number of evenly distributed stringers is n_st, and the number of ring frames is n_rf.

[0014] Furthermore, the rotationally symmetric model is a local model of the tank, including at least two stringers, two ring frames, and a skin; wherein the circumferential angle of the skin is 360° / n_st*2, and the axial height of the local model is the axial height of the tank l / n_rf*2.

[0015] Furthermore, the method for adding rotationally symmetric boundary conditions in step four is as follows: constrain the displacements of the left and right circumferential boundaries of the local rotationally symmetric model in cylindrical coordinates (U2, UR1, UR3); constrain the displacements of the lower axial boundary of the local model in cylindrical coordinates (U3, UR1, UR2); wherein the origin of the cylindrical coordinate system is the center of the lower edge of the skin, the direction of the R-axis of the cylindrical coordinate system is the radial direction of the skin, and the cylindrical coordinate system... The direction of the axis is tangential to the skin, and the direction of the Z-axis in the cylindrical coordinate system is from the lower center of the skin to the upper center of the skin.

[0016] Furthermore, the method for calculating the mass of the overall structure of the storage tank is as follows: Mass all =Mass part *(n_ st / 2)*(n_rf / 2), where Mass all For the overall structural quality, Mass part The weight is for the rotationally symmetric model.

[0017] Furthermore, the method for calculating the load-bearing capacity of the overall structure of the storage tank is as follows: N all =N part *(n_st / 2), where N all N represents the overall structural load-bearing capacity. part This refers to the load-bearing capacity of the rotationally symmetric model.

[0018] Furthermore, the material parameters of the tank structure described in step two include at least: the material density ρ_sk of the skin, the elastic modulus E_sk, and the yield strength σ. s _sk、tensile strength σ b _sk and elongation after fracture pe_sk; material density ρ_st, elastic modulus E_st, yield strength σ of the stringer s _st、tensile strength σ b _st and elongation after fracture pe_st; material density ρ_rf, elastic modulus E_rf, and yield strength σ of the ring frame. s _rf, tensile strength σ b _rf and post-fracture elongation pe_rf.

[0019] Furthermore, the load conditions described in step three include at least temperature load, internal pressure load, and axial pressure load.

[0020] Furthermore, the algorithms used for iterative optimization using the iSight optimization software in step five include, but are not limited to, sequence quadratic programming, multi-island genetic algorithm, and simulated annealing algorithm.

[0021] In another aspect, this invention provides a tank structure optimization design system based on a rotationally symmetric model, comprising at least a preset module, a modeling module, a data extraction module, and an optimization decision module. The preset module is used to set fixed dimensional parameters, design-to-optimize dimensional parameters, material parameters, and load conditions to be satisfied for the tank structure, and at least sets upper and lower limits for the design-to-optimize dimensional parameters based on process and raw material characteristics. The modeling module is used to combine the fixed dimensional parameters, design-to-optimize dimensional parameters, material parameters, and load conditions, and establish a rotationally symmetric model including local skins, stringers, and ring frames based on the finite element software Abaqus. The data extraction module is used to automatically extract the calculated results of the overall tank structure's mass, Mies stress, and load-bearing capacity from the finite element calculation results. The optimization decision module is used to perform iterative optimization using the ISight optimization software, with the minimization of the overall tank structure as the optimization objective and the satisfaction of the preset load conditions for the Mies stress and load-bearing capacity as constraints, until the optimal lightweight design scheme satisfying all constraints is obtained.

[0022] The present invention provides a method and system for optimizing the design of tank structures based on a rotationally symmetric model, which has at least one of the following beneficial effects:

[0023] I. This invention fundamentally solves the computational bottleneck of finite element analysis by establishing a rotationally symmetric local model to replace the traditional full-tank model. This model cleverly utilizes the mechanical properties of the tank, reducing the model size and computational complexity by several orders of magnitude while ensuring computational accuracy. Based on this, a fully automated parameter optimization process is integrated, realizing a closed loop from parametric modeling, rapid solution, result extraction to optimization decision-making. This invention shortens the traditional design cycle, which relies on manual trial and error and takes one to two months, to one to two days, significantly improving design efficiency, shortening the R&D cycle, and laying a solid foundation for the rapid iterative development of rockets.

[0024] Second, this invention is based on a rapid analysis loop, and the optimization algorithm can efficiently explore and screen among tens of thousands or even millions of design schemes, automatically finding the lightest or most efficient structural parameters that meet all strength and stiffness requirements. This tank design method surpasses the optimization limits achievable by human experience, thereby directly improving the rocket's payload capacity and achieving the synergistic maximization of tank structure lightweighting and load-bearing efficiency.

[0025] Upon reading the detailed embodiments and examining the accompanying drawings, those skilled in the art will recognize additional features and advantages. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a flowchart of a tank structure optimization design method based on a rotationally symmetric model according to an embodiment of the present invention.

[0028] Figure 2 This is a simplified flowchart of the tank structure optimization design method based on a rotationally symmetric model according to an embodiment of the present invention.

[0029] Figure 3 This is a schematic diagram of the T-shaped stringer cross-section of the tank structure according to an embodiment of the present invention.

[0030] Figure 4 This is a schematic diagram of the cross-section of the Z-shaped stringer of the storage tank structure according to an embodiment of the present invention.

[0031] Figure 5 This is a schematic cross-sectional view of the tank structure according to an embodiment of the present invention.

[0032] Figure 6 This is a schematic diagram of the rotationally symmetric finite element model of the storage tank according to an embodiment of the present invention. Detailed Implementation

[0033] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present invention and to exemplify the principles of the present invention, and are not configured to limit the present invention. In addition, the structural components in the drawings are not necessarily drawn to scale. For example, the dimensions of some structural components or regions in the drawings may be enlarged for other structural components or regions to aid in the understanding of the embodiments of the present invention.

[0034] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of the embodiments of the present invention. In the description of the present invention, it should be noted that, unless otherwise stated, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0035] Furthermore, the terms "comprising," "including," "having," or any other variations thereof are intended to cover non-exclusive inclusion, such that a structure or component that includes a list of elements includes not only those elements but also other structural elements that are not expressly listed or inherent to the structure or component. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the article or apparatus that includes the element.

[0036] Spatial relation terms such as "below," "under," "under," "low," "above," "on," and "high" are used for descriptive convenience to explain the positioning of one element relative to a second element, indicating that these terms are intended to cover different orientations of the device, in addition to those different from those shown in the figure. Furthermore, phrases such as "one element on / below another element" can indicate that two elements are in direct contact, or that there are other elements between the two elements. In addition, terms such as "first" and "second" are also used to describe individual elements, areas, parts, etc., and should not be considered limiting. Similar terms are used throughout the description to refer to similar elements.

[0037] It will be apparent to those skilled in the art that the present invention can be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention.

[0038] See Figure 1 This invention provides a method for optimizing the design of a storage tank structure based on a rotationally symmetric model, comprising at least the following steps:

[0039] S10. Determine the fixed dimensional parameters and the dimensional parameters to be optimized for the tank structure, and set the upper and lower limits of the dimensional parameters to be optimized based on the limitations of the process and raw material characteristics.

[0040] S20. Determine the material parameters of the storage tank structure;

[0041] S30. Determine the load conditions that the tank structure needs to meet;

[0042] S40. Using the finite element software Abaqus, combined with the fixed dimension parameters, the dimension parameters to be optimized, the material parameters, and the load conditions, establish a rotationally symmetric model including local skin, stringers, and ring frame, divide the finite element mesh, apply loads, and add rotationally symmetric boundary conditions.

[0043] S50. The rotationally symmetric model is solved by using the ISight optimization software to drive the finite element software Abaqus, and the calculation results of the mass, Mises stress and bearing capacity of the overall structure of the tank are extracted from the calculation results.

[0044] S60. With the goal of minimizing the overall structural mass of the storage tank, and with the stress of the mises and the load-bearing capacity satisfying the load conditions as optimization constraints, iterative optimization is performed using the iSight optimization software until the optimal lightweight design scheme that satisfies all constraints is obtained.

[0045] This invention provides a tank structure optimization design method based on a rotationally symmetric model. Utilizing the mechanical property of the tank structure's rotational symmetry along its circumference, a local model of the tank is established, significantly improving the speed of finite element analysis for load-bearing capacity. Based on this, by establishing a parameterized modeling, calculation, result extraction, and parameter optimization process for the tank structure, the efficiency of tank design and optimization is greatly improved. The cycle of one to two months required by traditional tank design methods is shortened to one to two days, increasing design efficiency by tens of times, laying a solid foundation for the rapid iterative development of rockets.

[0046] See Figure 3 , Figure 4 and Figure 5 Furthermore, regarding the fixed dimensional parameters and the design dimensional parameters to be optimized mentioned in step S10, the fixed dimensional parameters include the tank radius r and the tank axial height l, while the design dimensional parameters to be optimized include the skin thickness t_sk and the thickness t_st of each stringer plate. i The thickness of the ring frame is t_rf, and the width of each plate of the stringer is h_st. i The width h_rf of each plate in the ring frame i The number of evenly distributed stringers is n_st, and the number of ring frames is n_rf. It should be noted that the dimensional parameters in this embodiment need to be set with upper and lower limits based on process and material constraints to ensure the strength, stiffness, and stability of the tank structure.

[0047] Regarding process limitations: Taking skin thickness as an example, if the skin is joined using welding, its thickness cannot be too thin to ensure that it will not deform excessively during welding. If the skin is formed using bending, its thickness cannot be too thick. Once the skin thickness exceeds a certain upper limit, cold rolling becomes very difficult, and huge residual stress will be generated inside the material, potentially even causing cracks. Therefore, the lower limit of skin thickness must at least meet the thickness requirements of the welding process, while the upper limit must ensure that the skin can be bent and formed.

[0048] Regarding material property limitations: Taking stringer thickness as an example, the inherent properties of the material determine its usable size range. Exceeding this range may prevent the material from achieving its design performance or even cause it to fail. For instance, the strength and stiffness characteristics of the material (such as the modulus of elasticity E) dictate that the stringer must have a minimum thickness limit to ensure structural stability. Furthermore, excessively thick stringers, especially with high-density materials, can make them too heavy, contradicting the goal of minimizing tank mass. Therefore, the upper limit for stringer thickness must also be set with reference to the characteristics of the raw materials.

[0049] Therefore, when setting upper and lower limits for all design dimension parameters to be optimized in this embodiment, it is necessary to at least refer to the characteristics and limitations of the process and raw materials.

[0050] The tank structure optimization design method in this embodiment establishes a feasible domain that takes into account manufacturability, material properties, safety, system compatibility and economy by setting boundaries (upper and lower limits) for the tank size parameters, and optimizes within this range to finally obtain the optimal design scheme.

[0051] See also Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 ,and Figure 6 Furthermore, before optimizing the tank structure, it is necessary to determine the material parameters and load conditions that the tank structure must meet. Then, using the finite element software Abaqus, a rotationally symmetric model including the local skin, stringers, and ring frame is established by combining fixed dimensional parameters, the dimensional parameters to be optimized, material parameters, and load conditions. The material parameters of the tank structure mainly include those of the skin, stringers, and ring frame. In addition, the load conditions that the tank structure must meet include at least temperature loads, internal pressure loads, and axial compression loads.

[0052] Specifically, the material parameters of the skin include: density ρ_sk, elastic modulus E_sk, and yield strength σ. s _sk、tensile strength σ b _sk and elongation after fracture pe_sk. The material parameters of the stringer include: density ρ_st, elastic modulus E_st, yield strength σ_st, and elongation after fracture. s _st、tensile strength σ b The material parameters of the ring frame include: density ρ_rf, elastic modulus E_rf, and yield strength σ_rf. s _rf, tensile strength σ b _rf and post-fracture elongation pe_rf.

[0053] Furthermore, after determining the dimensional parameters, material parameters, and load conditions of the tank structure, the secondary development function of the finite element software Abaqus was used, combining fixed dimensional parameters (tank radius r and tank axial height l) and dimensional parameters to be optimized (skin thickness t_sk, thickness of each stringer plate t_st). i The thickness of the ring frame is t_rf, and the width of each plate of the stringer is h_st. i The width h_rf of each plate in the ring frame i Given the number of uniformly distributed stringers (n_st), the number of ring frames (n_rf), the material parameters of the skin, the stringers, and the ring frames, as well as the load conditions (temperature load, internal pressure load, and axial compression load), write a parametric modeling and calculation program for the tank structure based on a rotationally symmetric model. The main functions of the program include establishing a local model including the local skin, stringers, and ring frames, dividing the finite element mesh, establishing the connection relationship between the components of the model, applying loads, adding rotationally symmetric boundary conditions, and submitting the calculation.

[0054] The rotationally symmetric model in this embodiment is a partial model of the tank, including at least two stringers, two ring frames, and a skin. The circumferential angle of the skin is 360° / n_st*2, and the axial height of the partial model is the axial height of the tank, l / n_rf*2.

[0055] Next, using the secondary development capabilities of the finite element software Abaqus, a program was written to extract the calculation results. The extracted results mainly include the mass, Mies stress, and load-bearing capacity of the overall tank structure. Additionally, the optimization objective and constraints need to be determined. For example, the optimization objective is to minimize the overall mass of the tank structure, and the optimization constraints are to ensure that the Mies stress and load-bearing capacity meet the load conditions.

[0056] Finally, the optimization process is built using the iSight optimization software to drive modeling, calculation, extraction of calculation results and optimization parameters. The load conditions of the Mises stress and the bearing capacity are used as optimization constraints. The convergence conditions of the optimization algorithm are used to determine whether the tank structure has reached the optimization goal of minimizing mass. The iSight optimization software is used for iterative optimization until the optimal lightweight design scheme that satisfies all constraints is obtained.

[0057] The optimization algorithms in the above embodiments include, but are not limited to, sequential quadratic programming, multi-island genetic algorithm, and simulated annealing algorithm. Different optimization algorithms can be used for different embodiments. The iSight optimization software in this embodiment iteratively optimizes the size parameter to be optimized using any of the above optimization algorithms.

[0058] Furthermore, the method for adding rotationally symmetric boundary conditions in the above embodiments is as follows: constraining the displacements of the left and right circumferential boundaries of the local rotationally symmetric model in cylindrical coordinates (U2, UR1, UR3); constraining the displacements of the lower axial boundary of the local model in cylindrical coordinates (U3, UR1, UR2); wherein the origin of the cylindrical coordinate system is the center of the lower edge of the skin, the direction of the R-axis of the cylindrical coordinate system is the radial direction of the skin, and the cylindrical coordinate system... The direction of the axis is tangential to the skin, and the direction of the Z-axis in the cylindrical coordinate system is from the lower center of the skin to the upper center of the skin.

[0059] In any of the above embodiments, the finite element model is modeled by extracting the mid-surface to create shell elements.

[0060] Furthermore, in any of the above embodiments, the method for calculating the mass of the overall tank structure is as follows: Mass all =Mass part *(n_st / 2)*(n_rf / 2), where Mass all For the overall structural quality, Mass part The weight is for the rotationally symmetric model.

[0061] Furthermore, in any of the above embodiments, the method for calculating the load-bearing capacity of the overall tank structure is as follows: N all =N part *(n_st / 2), where N all N represents the overall structural load-bearing capacity. part This refers to the load-bearing capacity of the rotationally symmetric model.

[0062] See Figure 2 and Figure 4 The following is a further explanation with reference to specific embodiments:

[0063] Step 1: The stringer cross-section includes a U-shape. Determine the fixed dimensional parameters (tank radius r = 2250mm and tank axial height l = 4400mm), and determine the upper and lower limits of the dimensional parameters to be optimized, as shown in the table below:

[0064] t_sk <![CDATA[t_st1]]> t_rf <![CDATA[h_st1]]> <![CDATA[h_st2]]> <![CDATA[h_st3]]> lower limit 2.0 0.5 1.0 20.0 30.0 5.0 upper limit 2.5 2.0 3.0 40.0 50.0 20.0 <![CDATA[h_rf1]]> <![CDATA[h_rf2]]> <![CDATA[h_rf3]]> n_st n_rf lower limit 5.0 25.0 70.0 30 3 upper limit 20.0 50.0 120.0 100 9

[0065] Step 2: Determine the material parameters of the tank structure: E_sk = E_st = 18000MPa, E_rf = 68300MPa, σ s _sk=σ s _st = 1000MPa, σ s _rf=300MPa, σ b _sk=σ b _st=1680MPa, σ b_rf=450MPa, pe_sk=pe_st=22%, pe_rf=12%, ρ_sk=ρ_st=7.85g / cm 3 ρ_rf=2.85g / cm 3 .

[0066] Step 3: Determine the design load of the storage tank as follows: temperature -180℃, no internal pressure load, axial pressure load 11000kN.

[0067] Step 4: Using the secondary development function of the finite element software Abaqus, and combining the dimensional parameters, material parameters, and load conditions from Steps 1, 2, and 3, write a parametric modeling and calculation program for the tank structure based on a rotationally symmetric model. The main functions of the program include establishing a local model including local skin, stringers, and ring frame, dividing the finite element mesh, establishing the connection relationship between the components of the model, applying loads, adding rotationally symmetric boundary conditions, and submitting the calculation.

[0068] Step 5: Using the secondary development function of the finite element software Abaqus, write a program to extract the calculation results. The extracted results mainly include the mass of the overall tank structure, Mises stress, and load-bearing capacity.

[0069] Step Six: Use the iSight optimization software to build the optimization process, call and run the programs in Steps Four and Five, use the multi-island genetic algorithm for optimization, the optimization objective is to minimize the total mass of the tank structure, and the optimization constraint is that the axial compression instability load is greater than 11000kN.

[0070] Step 7: Run the optimization program. After 900 rounds of iterative optimization, the results are as follows:

[0071] t_sk <![CDATA[t_st1]]> t_rf <![CDATA[h_st1]]> <![CDATA[h_st2]]> <![CDATA[h_st3]]> Optimization value 2.0 0.58 1.5 28.1 41.2 8.0 <![CDATA[h_rf1]]> <![CDATA[h_rf2]]> <![CDATA[h_rf3]]> n_st n_rf Optimization value 12.0 37.1 115.0 57 4

[0072] The total optimization time for the tank structure in this embodiment was approximately 22 hours. The resulting tank structure can withstand an axial compressive load of 12210kN at -180℃, meeting the design requirements. The total weight of the structure is approximately 1170kg.

[0073] The above embodiments can be combined with each other and have corresponding technical effects.

[0074] Another aspect of the present invention provides a tank structure optimization design system based on a rotationally symmetric model, comprising at least a preset module, a modeling module, a data extraction module, and an optimization decision module. The preset module is used to set fixed dimensional parameters, design-to-optimize dimensional parameters, material parameters, and load conditions to be satisfied for the tank structure, and at least sets upper and lower limits for the design-to-optimize dimensional parameters based on process and raw material characteristics. The modeling module is used to combine the fixed dimensional parameters, design-to-optimize dimensional parameters, material parameters, and load conditions, and establish a rotationally symmetric model including local skins, stringers, and ring frames based on the finite element software Abaqus. The data extraction module is used to automatically extract the calculated results of the overall tank structure's mass, Mies stress, and load-bearing capacity from the finite element calculation results. The optimization decision module is used to perform iterative optimization using the ISight optimization software, with the minimization of the overall tank structure as the optimization objective and the satisfaction of the preset load conditions for the Mies stress and load-bearing capacity as constraints, until the optimal lightweight design scheme satisfying all constraints is obtained.

[0075] The tank structure optimization design system based on a rotationally symmetric model in this embodiment can quickly generate an initial design scheme close to the optimal solution by constructing an efficient parametric model and optimization algorithm, effectively overcoming the over-reliance on traditional design experience. Furthermore, the setting of upper and lower limits for parameters makes the design starting point more precise, significantly reducing the number of iterations required for subsequent finite element verification. At the same time, the optimization algorithm can automatically find the optimal solution, avoiding the lengthy process of repeatedly adjusting parameters and modeling manually, shortening the design cycle from several weeks to a few days or even less, achieving an order-of-magnitude improvement in design efficiency and significantly reducing time and economic costs.

[0076] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for optimizing the design of a storage tank structure based on a rotationally symmetric model, characterized in that, At least the following steps are included: Determine the fixed dimensional parameters and the dimensional parameters to be optimized for the tank structure, and set at least the upper and lower limits of the dimensional parameters to be optimized based on the process and raw material characteristics. Determine the material parameters of the storage tank structure; Determine the load conditions that the tank structure must meet; Using the finite element software Abaqus, combined with the fixed dimension parameters, the dimension parameters to be optimized, the material parameters, and the load conditions, a rotationally symmetric model including local skin, stringers, and ring frame is established. The finite element mesh is generated, the connection relationship between the components of the model is established, loads are applied, and rotationally symmetric boundary conditions are added. The rotationally symmetric model was solved by using the ISight optimization software to drive the finite element software Abaqus, and the calculation results of the mass, Mises stress and bearing capacity of the overall tank structure were extracted from the calculation results. With the goal of minimizing the overall structural mass of the storage tank, and with the stress of the mises and the load-bearing capacity satisfying the load conditions as optimization constraints, iterative optimization is performed using the iSight optimization software until the optimal lightweight design scheme that satisfies all constraints is obtained.

2. The tank structure optimization design method based on a rotationally symmetric model according to claim 1, characterized in that, The fixed dimensional parameters include the tank radius r and the tank axial height l; the dimensional parameters to be optimized include the skin thickness t_sk and the thickness of each stringer plate t_st. i The thickness of the ring frame is t_rf, and the width of each plate of the stringer is h_st. i The width h_rf of each plate in the ring frame i The number of evenly distributed stringers is n_st, and the number of ring frames is n_rf.

3. The tank structure optimization design method based on a rotationally symmetric model according to claim 2, characterized in that, The rotationally symmetric model is a partial model of the tank, including at least two stringers, two ring frames, and a skin; wherein the circumferential angle of the skin is 360° / n_st*2, and the axial height of the partial model is the axial height of the tank l / n_rf*2.

4. The tank structure optimization design method based on a rotationally symmetric model according to claim 3, characterized in that, The method for adding the rotational symmetry boundary conditions is as follows: constrain the displacements of the left and right circumferential boundaries of the local rotationally symmetric model in cylindrical coordinates (U2, UR1, UR3); constrain the displacements of the lower axial boundary of the local model in cylindrical coordinates (U3, UR1, UR2); wherein the origin of the cylindrical coordinate system is the center of the lower edge of the skin, the direction of the R-axis of the cylindrical coordinate system is the radial direction of the skin, and the cylindrical coordinate system... The direction of the axis is tangential to the skin, and the direction of the Z-axis in the cylindrical coordinate system is from the lower center of the skin to the upper center of the skin.

5. The tank structure optimization design method based on a rotationally symmetric model according to claim 4, characterized in that, The method for calculating the mass of the overall tank structure is as follows: Mass all =Mass part *(n_st / 2)*(n_rf / 2), where Mass all For the overall structural quality, Mass part The weight is for the rotationally symmetric model.

6. The tank structure optimization design method based on a rotationally symmetric model according to claim 5, characterized in that, The method for calculating the load-bearing capacity of the overall tank structure is as follows: N all =N part *(n_st / 2), where N all N represents the overall structural load-bearing capacity. part This refers to the load-bearing capacity of the rotationally symmetric model.

7. The tank structure optimization design method based on a rotationally symmetric model according to claim 6, characterized in that, The material parameters of the tank structure include at least: The material density ρ_sk, elastic modulus E_sk, and yield strength σ of the skin s _sk、tensile strength σ b _sk and elongation after fracture pe_sk; Material density ρ_st, elastic modulus E_st, yield strength σ of the stringers s _st、tensile strength σ b _st and post-fracture elongation pe_st; The material density ρ_rf, elastic modulus E_rf, and yield strength σ of the ring frame s _rf, tensile strength σ b _rf and post-fracture elongation pe_rf.

8. The tank structure optimization design method based on a rotationally symmetric model according to claim 1, characterized in that, The load conditions include at least temperature load, internal pressure load, and axial pressure load.

9. The tank structure optimization design method based on a rotationally symmetric model according to claim 1, characterized in that, The algorithms used for iterative optimization through the iSight optimization software include, but are not limited to, sequential quadratic programming, multi-island genetic algorithm, and simulated annealing algorithm.

10. A tank structure optimization design system based on a rotationally symmetric model, characterized in that, At least including: The preset module is used to set the fixed dimensional parameters, the dimensional parameters to be optimized, the material parameters, and the load conditions to be met for the tank structure, and to set the upper and lower limits of the dimensional parameters to be optimized based on the process and raw material characteristics. The modeling module is used to combine the fixed dimension parameters, the design dimension parameters to be optimized, the material parameters, and the load conditions, and to establish a rotationally symmetric model including local skin, stringers, and ring frame based on the finite element software Abaqus. The data extraction module is used to automatically extract the calculation results of the overall structure of the storage tank, including mass, Mises stress, and bearing capacity, from the finite element calculation results. The optimization decision module is used to perform iterative optimization using the iSight optimization software, with the goal of minimizing the overall mass of the storage tank structure and the constraints of the Mises stress and the bearing capacity meeting the preset load conditions, until the optimal lightweight design scheme that satisfies all constraints is obtained.

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