A method for topology optimization design of a steel pipe concrete sleeper structure based on APDL

Abstract

The application discloses a kind of based on APDL's steel pipe concrete sleeper structure topological optimization design method, belong to engineering technical field, it is connected to the connecting piece and sleeper block of steel pipe concrete sleeper respectively by setting topological optimization step, based on APDL language and using the method of structure topological optimization, the optimization of steel pipe concrete connecting piece and concrete sleeper block is completed, the quick acquisition of steel pipe concrete sleeper structure model after optimization is realized.The steel pipe concrete sleeper structure topological optimization design method based on APDL of the application, its design process is simple, can carry out optimization design to steel pipe concrete sleeper structure, so that the mass distribution of steel pipe concrete connecting piece and concrete sleeper block in sleeper structure is more reasonable, parameter design is more accurate, the anti-deformation, anti-damage capacity of steel pipe concrete sleeper structure is improved, the material consumption of steel pipe concrete sleeper structure is reduced, cost is saved, economic benefit is improved, with good practical value and application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of engineering technology, and particularly relates to a topological optimization design method for a steel pipe concrete sleeper structure based on APDL. BACKGROUND

[0002] The steel pipe concrete sleeper is a new type of sleeper which connects two concrete sleeper blocks by using a steel pipe concrete component, has good geometric shape maintaining capability, and can effectively ensure the overall strength, stiffness and stability of the sleeper structure, and thus has been increasingly widely applied in the field of rail transportation.

[0003] Generally, the steel pipe concrete sleeper comprises two steel pipes arranged side by side and concrete sleeper blocks connected at the end portions of the steel pipes, the two ends of the steel pipes are embedded in the concrete sleeper blocks, and the steel pipes are filled with concrete, so as to form a sleeper structure subjected to overall force. In the actual design and application of the steel pipe concrete sleeper, researchers have found that the structural difference and mass distribution difference of the steel pipe concrete connecting component and the concrete sleeper block have a great influence on the mechanical properties of the whole sleeper, and the existing steel pipe concrete sleeper still has a lot of optimization space in improving various performances in the use process, reducing the structural self-weight and the like, the structural design advantages have not been fully utilized and embodied, and the practicability and economy of the steel pipe concrete sleeper still need to be further improved, which also puts forward higher requirements for the construction and design of the steel pipe concrete. SUMMARY

[0004] In view of one or more of the above defects or improvement requirements of the prior art, the application provides a topological optimization design method for a steel pipe concrete sleeper structure based on APDL, which can optimize the structure of the steel pipe concrete sleeper in a topological optimization manner, reduce the self-weight of the sleeper structure, change the topological structure of the structure, improve the bearing capacity of the sleeper structure, and improve the defects of the existing steel pipe concrete sleeper, such as large material consumption, high cost and poor economic benefit.

[0005] To achieve the above object, the application provides a topological optimization design method for a steel pipe concrete sleeper structure based on APDL, which comprises the following steps:

[0006] S1, an initial finite element model of a steel pipe concrete connecting component is established, static force calculation is performed on the model, and the calculation results of the model are checked;

[0007] S2, a continuous structure topological optimization method based on the artificial density method is written into an ANSYS optimization iteration calculation program by using the APDL language of ANSYS;

[0008] S3, a steel pipe concrete connecting piece model is established, mesh is divided, and an optimization region in the model is defined, and a topological optimization design variable, an optimization target and an optimization constraint condition are determined;

[0009] S4, an optimization calculation is performed by using an ANSYS optimization iterative calculation program; if the calculation does not converge, a design variable is updated according to a calculation result until the calculation converges, and a final optimization model of the steel pipe concrete connecting piece is obtained;

[0010] S5, a complete steel pipe concrete sleeper three-dimensional model is established according to an optimization calculation result of the steel pipe concrete connecting piece size;

[0011] S6, the steel pipe concrete sleeper three-dimensional model is imported into a finite element calculation software, mesh is divided, a boundary condition is set and a corresponding load working condition is applied, and on this basis, a finite element static calculation is performed, and a calculation result is checked;

[0012] S7, a topological optimization design variable, an optimization target and an optimization constraint condition of the concrete sleeper block are defined;

[0013] S8, an optimization calculation is performed by using an ANSYS optimization iterative calculation program; if the calculation does not converge, a design variable is updated according to a calculation result, the process in S5 is performed again until the calculation converges, and a final optimization model is obtained;

[0014] S9, a steel pipe concrete sleeper is re-designed according to a topological structure of the concrete sleeper block obtained after optimization, and an optimal steel pipe concrete sleeper structure three-dimensional model is obtained by using three-dimensional software.

[0015] As a further improvement of the application, in S2, an algorithm realized by APDL includes the following processes:

[0016] (1) after the optimization region is determined, a material relative density field is established, and the material relative density is taken as a design variable;

[0017] (2) a SIMP material difference model is written, and a relationship between the material relative density field and material performance is connected, and the SIMP material difference model is described as follows:

[0018]

[0019]

[0020]

[0021]

[0022]

[0023] In the formula, is a density design variable; is a unit density design variable; C is a total flexibility of the structure; U is a displacement matrix; K is a total stiffness matrix; is a unit displacement matrix; is a unit stiffness matrix; P is a penalty factor; V is an optimized structure volume; is an initial volume of the entire design domain; is an optimized unit volume; is a volume ratio before and after optimization; is a load matrix; wherein the unit density design variable is between 0 and 1;

[0024] (3) after the interpolation calculation, an intermediate density material region is obtained, and a penalty calculation is performed on the intermediate density region, so that the relative density field of the material changes;

[0025] (4) by continuously updating the material density distribution, the density distribution of the optimized model is finally obtained.

[0026] As a further improvement of the present application, it further comprises the steps of:

[0027] S10, the three-dimensional model of the sleeper structure obtained after optimization is imported into the finite element calculation software, after meshing, the load case and boundary conditions in S6 are applied for static calculation, and the calculation results are compared with the results of S6 to check the strength of the optimized steel pipe concrete sleeper structure.

[0028] As a further improvement of the present application, the applied load cases include train load, hoisting load and construction load.

[0029] As a further improvement of the present application, in S1, design parameters need to be set for the initial finite element model; and

[0030] The design parameters include material properties of the steel pipe and the concrete, constraint conditions of the steel pipe at both ends, and bending and torsional load cases of the steel pipe concrete.

[0031] As a further improvement of the present application, in S3, the topological optimization design variable includes the diameter of the steel pipe and the wall thickness of the steel pipe;

[0032] And / or, the optimization target is the minimum volume of the steel pipe;

[0033] And / or, the optimization constraint condition includes the deflection value, stress and strain value and torsion angle of the steel pipe.

[0034] As a further improvement of the present application, in S7, the topological optimization design variable of the concrete sleeper block is the concrete sleeper block area unit density.

[0035] And / or, the optimization objective of the concrete sleeper block is the minimum volume of the concrete sleeper block.

[0036] And / or, the optimization constraint condition of the concrete sleeper block is that the sleeper block size meets the minimum arrangement requirements of the sleeper bolt hole and the minimum arrangement requirements of the steel pipe concrete connecting piece, equivalent stress and equivalent strain.

[0037] As a further improvement of the present application, in S1, the initial finite element model is established by a finite element calculation software, and the finite element calculation software includes but is not limited to abqus, ANSYS, Ansys workbench.

[0038] The above improved technical features can be combined with each other as long as they do not conflict with each other.

[0039] Overall, compared with the prior art, the above technical solutions conceived by the present application have the following beneficial effects:

[0040] (1) The APDL-based steel pipe concrete sleeper structure topological optimization design method of the present application optimizes the steel pipe concrete sleeper structure by using the method of structural topological optimization based on the APDL language, so that the mass distribution of the steel pipe concrete connecting piece and the concrete sleeper block is more reasonable, the weight is reduced, the amount of concrete and steel is reduced, and the economic benefit is improved.

[0041] (2) The APDL-based steel pipe concrete sleeper structure topological optimization design method of the present application can quickly optimize the sleeper structure by specifically optimizing the design steps, so that the distribution of the steel pipe concrete connecting piece and the anchoring length of the steel pipe in the concrete sleeper block are more reasonable, and the carrying capacity of the sleeper structure is effectively increased. At the same time, since the topological structure of the concrete sleeper block changes after optimization design, the bending stiffness of the concrete sleeper block is changed, the overall bending resistance of the sleeper is improved, and the resistance to damage of the sleeper structure is enhanced.

[0042] (3) The APDL-based steel pipe concrete sleeper structure topological optimization design method of the present application has a simple design process, can optimize the design of the steel pipe concrete sleeper structure, so that the mass distribution of the steel pipe concrete connecting piece and the concrete sleeper block in the sleeper structure is more reasonable, the parameter design is more accurate, the anti-deformation and anti-damage capacity of the steel pipe concrete sleeper structure is improved, the material consumption of the steel pipe concrete sleeper structure is reduced, the cost is saved, the economic benefit is improved, and the method has good practical value and application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings described below only show some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort based on these drawings.

[0044] Figure 1 is a flowchart of the APDL-based topological optimization design method for the steel pipe concrete sleeper structure in the embodiments of the present application;

[0045] Figure 2 is a structural schematic diagram of the steel pipe concrete sleeper in the embodiments of the present application. DETAILED DESCRIPTION

[0046] In order to make the objectives, technical solutions and advantages of the present application clearer, the following will further describe the present application in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as there is no conflict.

[0047] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0048] In addition, the terms "first", "second" are only used for description purpose, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0049] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "fixing" and the like should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integral; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship of two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0050] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. Moreover, the first feature "above", "over" and "on" the second feature can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "under" and "under" the second feature can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0051] Embodiment:

[0052] The flow of the APDL-based topological optimization design method for the concrete-filled steel tube sleeper structure in the preferred embodiment of the present application is shown in Figure 1 The full name of the technical term "APDL" is ANSYS Parametric Design Language, also known as "ANSYS Parametric Design Language". Its main use is that users organize ANSYS commands using a programming language to write parameterized user programs, thereby realizing the whole process of finite element analysis.

[0053] In the preferred embodiment, the technical scheme mainly establishes a structural design model of the concrete-filled steel tube through APDL, and optimizes the design of the concrete-filled steel tube structure on this basis, and completes the topological optimization design of the concrete-filled steel tube sleeper structure. At the same time, the concrete-filled steel tube sleeper in the present application mainly includes two components, namely a concrete-filled steel tube connector and a concrete sleeper block arranged at both ends of the connector, as shown in Figure 2 The design method in the present application is to design the structural design parameters of the above two components, so that the mass distribution of the sleeper structure is more reasonable, the weight of the sleeper structure is reduced, the consumption of concrete and steel is reduced, and the performance of the sleeper structure is improved while improving the economic benefit.

[0054] Specifically, the APDL-based topological optimization design method for the steel pipe concrete sleeper structure in the preferred embodiment mainly includes a topological design process for the steel pipe concrete connector and a topological design process for the concrete sleeper block. For the former, the method mainly includes the following steps:

[0055] S1, an initial finite element model of the steel pipe concrete connector is established by using a finite element calculation software, and corresponding design parameters are set for the initial finite element model; then, static calculation is performed on the model, and the calculation result of the model is checked. In actual design, the calculation result of the model is compared with experimental data to ensure that the initial finite element model meets the design requirements.

[0056] More specifically, the experimental data compared with the calculation result of the model are obtained through laboratory field tests, and the specific test process preferably includes: fixing both ends of the steel pipe concrete connector, applying a vertical load of 1 kN on the upper part of the steel pipe concrete connector to perform a bending resistance test; fixing one end of the steel pipe concrete connector and applying a torque load of 1 kN•m to the other end to perform a torsion resistance test. The corresponding experimental data are obtained through the field tests, and in the preferred embodiment, the calculation result of the model compared with the experimental data includes but is not limited to the maximum deflection displacement of the steel pipe concrete connector, the torsion angle, the maximum stress of the steel pipe, and the maximum tensile stress of the concrete.

[0057] In addition, in the preferred embodiment, the calculation result of the model meeting the design requirements should meet the following requirements: the bending deflection displacement limit is 2 mm, the stress of the steel pipe cannot exceed the yield strength of the steel, and the tensile stress of the concrete cannot exceed the tensile strength of the concrete.

[0058] In the preferred embodiment, the finite element calculation software used includes but is not limited to abqus, ANSYS, and Ansysworkbench, which correspondingly generate the initial finite element model for the steel pipe concrete connector.

[0059] Meanwhile, in the preferred embodiment, the design parameters for the initial finite element model of the steel pipe concrete connector include the material properties of the steel pipe and the concrete, the constraint conditions of the two ends of the steel pipe, and the bending and torsion resistance load working conditions of the steel pipe concrete.

[0060] S2, the basic algorithm of the artificial density method (i.e., the continuum structure topological optimization method based on the artificial density method) is written into the calculation software (ANSYS optimization iteration calculation program) through the APDL command stream, and the modeling and calculation process is parameterized.

[0061] Specifically, in the preferred embodiment, the basic principle of the algorithm implemented by APDL is as follows:

[0062] (1) After the optimization region is determined, the relative density field of the material is established, and the relative density of the material is taken as the design variable;

[0063] Here, the method for determining the optimization region is to select all the elements of the steel pipe and define the element type with the optimization algorithm written. Meanwhile, the "material" here refers to the steel pipe, and the concrete is poured into the steel pipe, which is associated with the geometric data of the steel pipe through parametric modeling, and changes cooperatively with the steel pipe.

[0064] (2) The SIMP material difference model is written to establish the relationship between the material relative density field and the material properties, and the SIMP material difference model is described as follows:

[0065]

[0066]

[0067]

[0068]

[0069]

[0070] In the formula, is the density design variable; is the element density design variable; C is the total flexibility of the structure; U is the displacement matrix; K is the total stiffness matrix; is the element displacement matrix; is the element stiffness matrix; P is the penalty factor; V is the volume of the structure after optimization; is the initial volume of the entire design domain; is the element volume after optimization; is the volume ratio before and after optimization; is the load matrix; wherein the element density design variable is between 0 and 1.

[0071] In addition, it should be noted that the artificial density method optimization here includes the following contents: assuming that the material of the structure to be optimized is a material with variable density, and on this basis, the relationship between the material density and the material properties such as elastic modulus and Poisson's ratio is established. The material density here is actually the relative density, with a maximum value of 1 and a minimum value of 0. Through the difference model in the optimization algorithm, the redistribution of the material density of the structure under different working conditions can be obtained, thereby realizing the optimization of the structure.

[0072] In actual design, a material density distribution field can be established by writing a program in ANSYS and according to the variable material density, and under the action of the load, the iterative calculation is carried out by using the difference model algorithm in the written optimization criterion to obtain the density redistribution field of each unit. The unit density in the density field is called intermediate density. The intermediate density is made to approach 0 or 1 by introducing a penalty factor through the difference model. Finally, the structure part with the density of 0 is the part to be optimized out.

[0073] (3) The steel pipe concrete connecting piece model is established through APDL in the classic interface of ANSYS, the intermediate density material region is obtained after difference calculation, and the penalty calculation is performed on the intermediate density region to make the relative density field of the material change.

[0074] After the difference calculation is completed, the mechanical analysis finite element calculation is performed on the model to obtain the relative density redistribution of the optimized unit. The region of the relative density redistribution is the intermediate density material region. The penalty function in the difference algorithm is used for calculation to make the unit density design variable become 0 or 1.

[0075] It should be noted that the initial finite element model in step S1 does not introduce the artificial density method, but is only a simple structure static analysis model. The purpose is to check whether the initial structure model before optimization meets the requirements of test test. Only the model meeting the requirements can be further optimized. Thus, it can be seen that the steel pipe concrete connecting piece model established through APDL is the model checked before. The finite element grid forms and unit types of the two established models are different from each other. The calculation process of the steel pipe concrete connecting piece model is different from that of the initial finite element model.

[0076] (4) The density distribution of the optimized model is finally obtained by continuously updating the material density distribution.

[0077] S3, grid division is performed on the model, and the optimization region in the model is defined to determine the topological optimization design variable, the optimization target and the optimization constraint condition;

[0078] In actual operation, the optimization region is preferably defined as the entire steel pipe concrete connecting piece. Meanwhile, the topological optimization design variable in the preferred embodiment includes the steel pipe diameter and the steel pipe wall thickness, the optimization target is the minimum steel pipe volume, and the optimization constraint condition includes the steel pipe deflection value, the stress and strain value and the steel pipe torsion angle.

[0079] S4, optimization calculation is performed through a program algorithm (ANSYS optimization iterative calculation program). If the calculation does not converge, the design variable (material relative density) is updated according to the calculation result, the calculation process in S2 is performed again, until the calculation converges, and the final optimized model of the steel pipe concrete connecting piece is obtained.

[0080] S5, according to the engineering experience and experimental data, the preliminary size of the concrete sleeper block is determined, and then combined with the optimization calculation result of the size of the steel pipe concrete connecting piece in S4, a complete initial three-dimensional model of the concrete sleeper is established;

[0081] S6, the three-dimensional model of the steel pipe concrete sleeper is imported into the finite element calculation software, simulated by using a solid element (solid), and then the boundary conditions are set and the corresponding load cases are applied, on this basis, the finite element static analysis is carried out, and the analysis result is compared with the experimental result, so as to ensure that the initial model meets the design requirements; in the preferred embodiment, the applied load cases include train load, lifting load and construction load.

[0082] S7, meshing is carried out, the optimization area is set as the concrete sleeper block, the unit density of the concrete sleeper block area is defined as the topological optimization design variable, and the steel pipe concrete connecting piece is defined as the non-design variable, and the optimization target and optimization constraint condition of the concrete sleeper block are determined.

[0083] In the preferred embodiment, the optimization target of the concrete sleeper block is the minimum volume of the concrete sleeper block, and the constraint condition is that the size of the sleeper block meets the minimum arrangement requirement of the sleeper bolt hole and the minimum arrangement requirement of the steel pipe concrete connecting piece, equivalent stress and equivalent strain;

[0084] S8, optimization calculation is carried out through the APDL optimization program, if the calculation does not converge, the design variable is updated according to the calculation result, the process in S5 is carried out again, until the calculation converges, and the final optimization model is obtained;

[0085] It should be noted that the core calculation method of the "APDL optimization program" here is the same as the program algorithm in S4, the main difference is that the modeling code and the post-processing code of the data are different, so it is not described here.

[0086] S9, the steel pipe concrete sleeper is re-designed according to the topological structure of the concrete sleeper block obtained after optimization, and the optimal three-dimensional model of the steel pipe concrete sleeper structure is obtained through three-dimensional software;

[0087] S10, the three-dimensional model of the sleeper structure obtained after optimization is imported into the finite element calculation software, after meshing, the load cases and boundary conditions in S6 are applied for static calculation, and the calculation result is compared with the result of S6, to check the strength of the optimized steel pipe concrete sleeper structure.

[0088] Through the above process, the structure design optimization process of the steel pipe concrete connecting piece and the concrete sleeper block can be completed respectively, the design optimization efficiency is improved, and the optimization cost is saved.

[0089] The APDL-based topological optimization design method of the steel pipe concrete sleeper structure in the application has a simple design process, can optimize the design of the steel pipe concrete sleeper structure, makes the mass distribution of the steel pipe concrete connecting piece and the concrete sleeper block in the sleeper structure more reasonable, the parameter design more accurate, improves the anti-deformation and anti-damage capacity of the steel pipe concrete sleeper structure, reduces the material consumption of the steel pipe concrete sleeper structure, saves the cost, improves the economic benefit, and has good practical value and application prospect.

[0090] Those skilled in the art can easily understand that the above description is only preferred embodiments of the present application, and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for topology optimization design of a steel pipe concrete sleeper structure based on APDL, characterized in that, The method comprises the following steps: S1, establishing an initial finite element model of the steel pipe concrete connecting piece, performing static calculation on the model, and checking the calculation results of the model; S2, writing a continuous structure topology optimization method based on the artificial density method into an ANSYS optimization iterative calculation program through the APDL language of ANSYS; S3, establishing a steel pipe concrete connecting piece model, performing mesh division on the model, defining an optimization region in the model, and determining topology optimization design variables, an optimization target, and optimization constraint conditions; S4, performing optimization calculation by using the ANSYS optimization iterative calculation program; if the calculation does not converge, updating the design variables according to the calculation results until the calculation converges, and obtaining a final optimization model of the steel pipe concrete connecting piece; S5, establishing a complete steel pipe concrete sleeper three-dimensional model according to the optimization calculation results of the size of the steel pipe concrete connecting piece; S6, importing the steel pipe concrete sleeper three-dimensional model into a finite element calculation software, performing mesh division, setting boundary conditions and applying corresponding load cases, and on this basis, performing finite element static calculation and checking the calculation results; S7, defining topology optimization design variables, an optimization target, and optimization constraint conditions of the concrete sleeper block; S8, performing optimization calculation by using the ANSYS optimization iterative calculation program; if the calculation does not converge, updating the design variables according to the calculation results, re-performing the process in S5 until the calculation converges, and obtaining a final optimization model; S9, re-designing the steel pipe concrete sleeper according to the topology structure of the concrete sleeper block obtained after optimization, and obtaining an optimal steel pipe concrete sleeper structure three-dimensional model through three-dimensional software.

2. The APDL-based topological optimization design method of a steel pipe concrete sleeper structure according to claim 1, characterized in that, In S2, the algorithm implemented by APDL comprises the following processes: (1) after the optimization region is determined, a material relative density field is established, and the material relative density is taken as a design variable; (2) a SIMP material interpolation model is written, a relationship between the material relative density field and the material performance is established, and the SIMP material interpolation model is described as follows: wherein is the density design variable; is the cell density design variable; C is the total flexibility of the structure; U is the displacement matrix; K is the total stiffness matrix; is the cell displacement matrix; is the cell stiffness matrix; P is the penalty factor; V is the optimized structure volume; is the initial volume of the entire design domain; is the optimized cell volume; is the volume ratio before and after optimization; is the load matrix; wherein the cell density design variable is between 0 and 1; (3) after interpolation calculation, an intermediate density material region is obtained, and penalty calculation is performed on the intermediate density region, so that the material relative density field changes; (4) the material density distribution is continuously updated, and finally the density distribution of the optimization model is obtained.

3. The APDL-based topological optimization design method of a steel pipe concrete sleeper structure according to claim 1, characterized in that, The method further comprises the following steps: S10, importing the sleeper structure three-dimensional model obtained after optimization into a finite element calculation software, performing mesh division, applying the load cases and boundary conditions in S6 to perform static calculation, comparing the calculation results with the results in S6, and checking the strength of the optimized steel pipe concrete sleeper structure.

4. The APDL-based topological optimization design method of a steel pipe concrete sleeper structure according to claim 1 or 3, characterized in that, The applied load cases include train load, hoisting load, and construction load.

5. The APDL-based topological optimization design method of a concrete-filled steel tubular sleeper structure according to any one of claims 1 to 3, characterized in that, In S1, design parameters need to be set for the initial finite element model; and The design parameters include material properties of the steel pipe and the concrete, constraint conditions of the steel pipe at both ends, and steel pipe concrete bending and torsional load cases.

6. The APDL-based topological optimization design method of a concrete-filled steel tubular sleeper structure according to claim 1, characterized in that, In S3, the topology optimization design variables include the steel pipe diameter and the steel pipe wall thickness; and / or, the optimization target is the minimum steel pipe volume; and / or, the optimization constraint conditions include the steel pipe deflection value, stress and strain value, and steel pipe torsion angle.

7. The APDL-based topological optimization design method of a concrete-filled steel tubular sleeper structure according to any one of claims 1 to 3 or 6, characterized in that, In S7, the topology optimization design variable of the concrete sleeper block is the concrete sleeper block area unit density; And / or, the optimization objective of the concrete sleeper block is the minimum volume of the concrete sleeper block; And / or, the optimization constraint condition of the concrete sleeper block is that the sleeper block size meets the minimum arrangement requirements of the sleeper bolt hole and the minimum arrangement requirements of the steel pipe concrete connecting piece, the equivalent stress, and the equivalent strain.

8. The APDL-based topological optimization design method of a concrete-filled steel tubular sleeper structure according to any one of claims 1 to 3, characterized in that, In S1, an initial finite element model is established by a finite element calculation software, and the finite element calculation software includes abqus, ANSYS, and Ansys workbench.

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