A feature-reconstruction design method for shield machine cutterhead panel structure

Abstract

A feature-reconstruction design method for a shield machine cutterhead panel structure comprises the following steps: firstly determining the tool arrangement of the shield machine cutterhead panel and establishing a mechanical simulation model of the shield machine cutterhead panel; extracting a domain to be analyzed and geometric and physical conditions based on an actual shield machine cutterhead panel structural design problem; then establishing a feature-reconstruction design domain topology model for the shield machine cutterhead panel; then establishing a feature-reconstruction design mathematical model; taking minimization of flexibility, i.e., optimal structural stiffness, as an objective function, adopting a variable density method to describe a structural optimization method, establishing an optimization model driven by a physical field, and determining the optimization direction each time; then performing iterative optimization of the shield machine cutterhead panel structure to obtain a shield machine cutterhead panel structure with maximum stiffness under a fixed volume ratio constraint; and finally post-processing the optimized shield machine cutterhead panel structure. The present invention improves design efficiency and quality.

Description

Technical Field

[0001] The present invention belongs to the technical field of shield machine cutter head panel structure design, and in particular relates to a feature reconstruction design method for a shield machine cutter head panel structure. Background Art

[0002] With the increasing demand for underground space infrastructure in human society, shield machines have been widely used in the construction of mountain tunnels and underground rail transit facilities. The cutterhead panel of the shield machine, as one of the most critical components of the shield machine, plays a vital role in tunnel excavation. The quality of the cutterhead panel structure directly affects the excavation work of the shield machine.

[0003] The working conditions of shield machines are complex and harsh. At present, most shield machine panel designs are based on experience to design panel reinforcements. The stress analysis is basically based on the friction between the panel and the soil layer to optimize the panel design (Feng Chang, Zhu Shumin, Chen Guosan. Optimization design and analysis of earth pressure balance shield cutterhead [J]. Mechanical Manufacturing and Automation, 2017, 46(03): 144-147+188. DOI: 10.19344 / j.cnki.issn1671-5276.2017.03.041.). The stress conditions of each cutting tool on the panel are not fully considered. The cutterhead panel reinforcement structure obtained by such optimization cannot be applied to the actual stress conditions of the cutter when the shield machine panel is working. Summary of the Invention

[0004] In order to overcome the shortcomings of the above-mentioned technology, the purpose of the present invention is to provide a feature reconstruction design method for the cutter head panel structure of a shield machine, thereby improving the efficiency and quality of the design.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0006] A feature reconstruction design method for a shield machine cutterhead panel structure includes the following steps:

[0007] 1) Determine the mechanical simulation model of the shield machine panel:

[0008] 1.1) Determine the relevant parameters of the shield machine panel:

[0009] The parameters of the shield machine panel required for preliminary design optimization include: shield machine outer diameter d0, maximum cutting diameter of the tool d1, center tool cutting radius d2, cutterhead positive cutting tool width b1, tool overlap e, cutterhead spoke number N, and edge cutting tool width b2;

[0010] 1.2) Determine the cutter head and tool layout:

[0011] The minimum number of positive cutters required for the shield machine panel is:

[0012]

[0013] The number of positive cutting tools N1 on the cutter head is rounded to N0, and the overlap between the positive cutting tool and the center tool is:

[0014] c=(b1-e)×(N0-N1) (2)

[0015] Then the initial value of the tangent Archimedean spiral is:

[0016]

[0017] The Archimedean spiral coefficient α is:

[0018]

[0019] Then the equation of the spiral arrangement curve of the cutter head is:

[0020] ρ=ρ0+αθ (5)

[0021] Add other shield machine cutters and determine the cutter layout results for the entire cutterhead panel;

[0022] 2) Establishing a shield machine cutterhead panel feature reconstruction model:

[0023] 2.1) Establishing the shield machine cutterhead panel feature reconstruction design domain topology model:

[0024] The design domain topology model is established according to the determined cutterhead structure. The feature reconstruction design method adopted uses isotropic pseudo-density units as the minimum unit for structural optimization. The design domain is represented as closely arranged pseudo-density units. The pseudo-density value x of the pseudo-density unit is used as the design variable, which reflects the correspondence between material density and material properties. The pseudo-density values ​​of 1 and 0 represent the presence or absence of structure at that position, respectively. The design variable field x = {x1, x2, ..., x i ,...} T Characterize the structure distribution in the design domain, and define the design domain and non-design domain of the structure according to the pseudo-density value;

[0025] 2.2) Establishing a mathematical model for feature reconstruction design method:

[0026] The structural design goal is to determine the optimal structural path for transmitting the cutting force exerted on the cutter head panel of the shield machine to the bracket flange and the panel fixing point. The design goal is to maximize the stiffness of the panel structure. Therefore, the objective function of the optimization mathematical model is c(x), and the constraint function is the opening ratio of the shield machine panel, that is, the final material volume fraction f in the design domain. The panel material is determined. For the design goal and constraint function, the following mathematical model of the feature reconstruction design method is established:

[0027]

[0028] Where: x e is the unit density, i.e. the design variable; U is the displacement matrix; K is the stiffness matrix; V (x) is the structural volume; V0 is the total volume; f is the volume fraction; u e is the unit displacement vector; k0 is the unit stiffness matrix; p is the penalty factor;

[0029] 2.3) Sensitivity analysis of feature reconstruction design method:

[0030] Before performing the iterative algorithm, it is necessary to perform a sensitivity analysis of the objective function relative to the design variables. When performing the sensitivity analysis, the unit displacements of the i force points need to be accumulated. The final sensitivity function is as follows:

[0031]

[0032] 3) Iterative optimization of shield machine panel structure:

[0033] The optimal structural model is obtained through continuous iterative optimization of the material pseudo-density value. The design variables, objective function, constraint function and their sensitivity to the design variables obtained in the previous steps are used as input. The gradient-based OC algorithm is used to optimize the mathematical model of the feature reconstruction design method and update the design variables until the objective function converges while satisfying the constraints. This results in the optimal panel structure that meets the material usage requirements.

[0034] 4) Structural post-processing:

[0035] The optimized shield machine panel structure is smoothed and rounded, and then further modified according to the processing technology requirements and manufacturing and assembly requirements to obtain the final design.

[0036] The present invention has the following beneficial results:

[0037] Since the present invention does not rely on the long-term design experience of designers, it can reduce the design labor costs of enterprises. The present invention uses feature reconstruction design and innovatively proposes to optimize the characteristics of the panel structure based on the actual stress conditions of the cutters on the shield machine cutterhead panel. Therefore, the design results have a better theoretical basis, the final structure is more reasonable, and the performance is better.

[0038] Compared with the current mainstream shield machine panel design method, the use of the present invention no longer requires repeated design, simulation, and improvement work during design, which significantly improves work efficiency and design performance, thereby helping enterprises better cope with the rapidly changing market and achieve better production benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Flowchart of the present invention.

[0040] Figure 2 Schematic diagram of the cutter head tool arrangement according to an embodiment of the present invention.

[0041] Figure 3 This is a schematic diagram of the shield machine panel feature reconstruction results according to an embodiment of the present invention.

[0042] Figure 4 This is a schematic diagram of the shield machine panel structure design according to an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The present invention is described in detail below with reference to the accompanying drawings and embodiments. The method of the present invention can be used for the structural design of various spoke shield machine panels. The embodiment takes the structural design of a certain model of 4-spoke shield as an example.

[0044] Reference Figure 1 A feature reconstruction design method for a shield machine cutterhead panel structure includes the following steps:

[0045] 1) Determine the mechanical simulation model of the shield machine panel:

[0046] 1.1) Determine the relevant parameters of the shield machine panel:

[0047] The parameters of the shield machine panel required for preliminary design are: shield machine outer diameter d0 = 6280mm, maximum cutting diameter of the tool d1 = 6300mm, center tool cutting radius d2 = 1900mm, cutter head positive cutting tool width b1 = 100mm, tool overlap e = 4mm, cutter head spoke number N = 4, side cutting tool width b2 = 150mm, and the positive cutting tool adopts a double helix arrangement;

[0048] 1.2) Determine the cutter head and tool layout:

[0049] The minimum number of positive cutters required for the shield machine panel is:

[0050]

[0051] The number of positive cutting tools N1 on the cutter head is rounded to N0 = 22, and the overlap between the positive cutting tool and the center tool is:

[0052] c=(b1-e)×(N0-N1)=(100-4)×(22-21.35)=62.4 (2)

[0053] Then the initial value of the tangent Archimedean spiral is:

[0054]

[0055] The Archimedean spiral coefficient α is:

[0056]

[0057] Then the double helix arrangement curve equation of the cutter head positive cutting tool arrangement is:

[0058]

[0059]

[0060] Shell knives are evenly distributed along the circumference of the outermost edge of the knife disc. In this embodiment, 4 shell knives are evenly distributed between the 4 spokes. The final arrangement of the knives on the knife disc is as follows: Figure 2 As shown, it can be seen from the figure that the hollow circle represents the position of the cutting knife, and the solid circle is the position where the four shell knives are arranged;

[0061] 2) Establishing a shield machine cutterhead panel feature reconstruction model:

[0062] 2.1) Establishing the shield machine cutterhead panel feature reconstruction design domain topology model:

[0063] The design domain topology model is established according to the determined cutterhead structure. The feature reconstruction design method adopted uses isotropic pseudo-density units as the minimum unit for structural optimization. The design domain is represented as closely arranged pseudo-density units. The pseudo-density value x of the pseudo-density unit is used as the design variable, which reflects the correspondence between material density and material properties. The pseudo-density values ​​of 1 and 0 represent the presence or absence of structure at that position, respectively. The design variable field x = {x1, x2, ..., x i ,...} T The structural distribution in the design domain is characterized. The soil mobility in the center of the shield machine is small, which is prone to accumulation and cutting. The force on the cutter increases with the radius of the shield machine. In this embodiment, the force at the center is ignored and the central pseudo-density value is defined as 0 in advance. The force in the design domain is the shield machine panel cutter layout position determined in the previous step. The fixed constraint point is the overlap surface between the shield machine bracket flange and the shield machine cutter head panel.

[0064] 2.2) Establishing a mathematical model for feature reconstruction design method:

[0065] The structural design goal of this embodiment is to transfer the determined cutter force of the shield machine panel to the optimal structural path between the panel, the bracket flange, and the panel fixing point. The design goal is to maximize the stiffness of the panel structure. Therefore, the objective function of the optimization mathematical model is c(x), and the constraint function is the opening ratio of the shield machine panel, that is, the final material volume fraction f in the design domain. The panel material is Q235, so the Young's modulus used in the unit stiffness matrix K is 210 GPa and the Poisson's ratio is 0.3. For the design goal and constraint function, the following topology optimization mathematical model is established:

[0066]

[0067] Where: x e is the unit density, i.e. the design variable; U is the displacement matrix; K is the stiffness matrix; V (x) is the structural volume; V0 is the total volume; f is the volume fraction; u e is the unit displacement vector; k0 is the unit stiffness matrix; p is the penalty factor;

[0068] 2.3) Sensitivity analysis of feature reconstruction design method:

[0069] Before performing the iterative algorithm, a sensitivity analysis of the objective function relative to the design variables is required. The shield machine cutterhead panel used in this embodiment has many stress points. Therefore, when performing the sensitivity analysis, the unit displacements of these i stress points need to be accumulated. The final sensitivity function is as follows:

[0070]

[0071] 3) Iterative optimization of shield machine panel structure:

[0072] The optimal structural model is obtained by continuous iterative optimization of the material pseudo-density value. The design variables, objective function, constraint function and their sensitivity to the design variables obtained in the previous steps are used as inputs. The gradient-based OC algorithm is used to optimize the mathematical model of the feature reconstruction design method and update the design variables until the objective function converges while satisfying the constraint conditions, thereby obtaining the optimal panel structure that meets the material usage. The convergence condition of this embodiment is that the difference between the objective functions of two adjacent iterations is less than 0.01. At the end of the optimization, the volume fraction of the design result is 40% of the entire design domain. The final feature reconstruction design structure is as follows: Figure 3 As shown, it can be seen that the cross structure in the center is the spoke of the cutter head, and the rest is the panel structure obtained by feature reconstruction design;

[0073] 4) Structural post-processing:

[0074] The optimized shield machine panel structure is smoothed and rounded, and then further modified according to the processing technology requirements and manufacturing and assembly requirements to obtain the final design. The result of the smoothed and rounded shield machine panel structure is as follows: Figure 4 shown.

Claims

1. A feature reconstruction design method for a shield machine cutterhead panel structure, characterized in that: The following steps are involved: 1) Determine the mechanical simulation model of the shield machine panel: 1.1) Determine the relevant parameters of the shield machine panel: The parameters of the shield machine panel required for preliminary design optimization include: shield machine outer diameter d0, maximum cutting diameter of the tool d1, center tool cutting radius d2, cutterhead positive cutting tool width b1, tool overlap e, cutterhead spoke number N, and edge cutting tool width b2; 1.2) Determine the cutter head and tool layout: The minimum number of positive cutters required for the shield machine panel is: The number of positive cutting tools N1 on the cutter head is rounded to N0, and the overlap between the positive cutting tool and the center tool is: c=(b1-e)×(N0-N1) (2) Then the initial value of the tangent Archimedean spiral is: The Archimedean spiral coefficient α is: Then the equation of the spiral arrangement curve of the cutter head is: ρ=ρ0+αθ (5) Add other shield machine cutters and determine the cutter layout results for the entire cutterhead panel; 2) Establishing a shield machine cutterhead panel feature reconstruction model: 2.1) Establishing the shield machine cutterhead panel feature reconstruction design domain topology model: The design domain topology model is established according to the determined cutterhead structure. The feature reconstruction design method adopted uses isotropic pseudo-density units as the minimum unit for structural optimization. The design domain is represented as closely arranged pseudo-density units. The pseudo-density value x of the pseudo-density unit is used as the design variable, which reflects the correspondence between material density and material properties. The pseudo-density values ​​of 1 and 0 represent the presence or absence of structure at that position, respectively. The design variable field x = {x1, x2, ..., x i ,...} T Characterize the structure distribution in the design domain, and define the design domain and non-design domain of the structure according to the pseudo-density value; 2.2) Establishing a mathematical model for feature reconstruction design method: The structural design goal is to determine the optimal structural path for transmitting the cutting force exerted on the cutter head panel of the shield machine to the bracket flange and the panel fixing point. The design goal is to maximize the stiffness of the panel structure. Therefore, the objective function of the optimization mathematical model is c(x), and the constraint function is the opening ratio of the shield machine panel, that is, the final material volume fraction f in the design domain. The panel material is determined. For the design goal and constraint function, the following mathematical model of the feature reconstruction design method is established: Where: x e is the unit density, i.e. the design variable; U is the displacement matrix; K is the stiffness matrix; V(x) is the structural volume; V0 is the total volume; f is the volume fraction; u e is the unit displacement vector; k0 is the unit stiffness matrix; p is the penalty factor; 2.3) Sensitivity analysis of feature reconstruction design method: Before performing the iterative algorithm, it is necessary to perform a sensitivity analysis of the objective function relative to the design variables. When performing the sensitivity analysis, the unit displacements of the i force points need to be accumulated. The final sensitivity function is as follows: 3) Iterative optimization of shield machine panel structure: The optimal structural model is obtained through continuous iterative optimization of the material pseudo-density value. The design variables, objective function, constraint function and their sensitivity to the design variables obtained in the previous steps are used as inputs. The gradient-based OC algorithm is used to optimize the mathematical model of the feature reconstruction design method and update the design variables. Until the objective function converges while satisfying the constraints, the optimal panel structure that meets the material usage is obtained; 4) Structural post-processing: The optimized shield machine panel structure is smoothed and rounded, and then further modified according to the processing technology requirements and manufacturing and assembly requirements to obtain the final design.

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