Topological optimization and stability assessment method for cantilever base assembly

Abstract

The invention provides a topological optimization and stability assessment method for a cantilever base assembly, and relates to the technical field of lightweight design of electrified railway contact network parts, and the method comprises the steps: building a finite element model of the cantilever base assembly; simplifying boundary conditions of independent key parts in the finite element model to obtain a simplified finite element model; the method comprises the following steps: selecting an independent key part except an area applying constraint and load as an optimization object, taking the minimum total variable performance of a structure under the action of a given load as a target, taking volume fraction response as constraint, and obtaining a structure configuration with the maximum rigidity through topological optimization; and performing stability strength evaluation on the topological optimized structural configuration by adopting a direct periodic method to obtain a stability load. By the adoption of the scheme, light weight of the cantilever base assembly structure can be achieved under the condition that the use requirement is met.

Description

Technical Field

[0001] The present application relates to the technical field of lightweight parts for electrified railway contact networks, and in particular to a method and device for topological optimization and stability strength evaluation of a cantilever-base assembly. Background Art

[0002] In recent years, high-speed railways have developed rapidly. At present, most high-speed railway lines use electric traction, and the overhead contact system is an important part of the railway power supply system. In the past, due to economic and technical conditions, the design margin of the components of the overhead contact support connection device was very large, resulting in quality redundancy in many components. Lightweight design of these components can not only save materials and reduce costs, but also reduce the load of the entire overhead contact system and reduce the burden on the arm and support.

[0003] As one of the supporting connection devices, the cantilever base assembly plays the role of supporting the suspension system, transmitting loads, and ensuring the precise position and stability of the cantilever device. At present, the actual load-bearing capacity of the cantilever base assembly is much higher than the standard requirements, with a high safety factor and room for weight reduction, and its load-bearing capacity can be further explored.

[0004] The arm base assembly is subjected to alternating loads for a long time during service, so the optimized configuration must meet certain fatigue strength. Shakeup refers to the phenomenon that after a certain initial plastic deformation occurs under alternating loads, the subsequent plastic accumulation stops and the response becomes a pure elastic response. If the structure is in an elastically stable state, high-cycle fatigue failure will not occur. Therefore, shakeup analysis can reasonably utilize the strength margin between the structure entering yield and the occurrence of destruction, give full play to the bearing capacity of the material, reduce the use of materials, thereby reducing costs and improving economic benefits. At present, the shakeup theory has also been widely used in practical engineering problems such as civil engineering, transportation, and aerospace.

[0005] Currently, researchers have conducted relevant research on the arm base structure and related parts of the high-speed railway contact network system.

[0006] Prior art 1 takes the contact network arm base body and rotating flat ears as research objects, uses SolidWorks to establish a three-dimensional model of the arm base assembly, imports Ansys to solve the stress distribution of the parts, and conducts static analysis on the arm base assembly. Prior art 2 In view of the inconvenient installation and heavy weight of the single arm base body channel steel welded back plate structure, a new single arm base structure is proposed, which reduces weight by more than 10%, has a wider field of view during installation, and is more convenient to operate.

[0007] Patents CN217374222U and CN214028296U both take into account factors such as installation efficiency and reliability from the perspective of new configuration design, and design a new arm base structure that is easy to install and maintain, and has high safety and reliability. Patent CN116484667A provides a structural topology optimization and stability assessment method for the support connector, which first performs topology optimization on the structure, then calculates the stability limit load of the new structure through programming, and finally verifies the calculation results using the incremental finite element method.

[0008] In summary, it can be seen that the existing research on the arm base is basically focused on the simulation analysis, strength verification and design of new configurations of parts, and rarely forms a complete lightweight design method. In the topology optimization and stability assessment method of the supporting connector structure, the way to simplify the structure from the assembly to the part is to apply an equivalent concentrated load on the contact surface. This loading method not only has errors when restoring the stress state of the structure, but also easily causes stress concentration at the equivalent load, and cannot be used for the simplification of complex assemblies. The subsequent method of calculating the stability limit load by programming can only be used for a single part and cannot be applied to the assembly. In addition, the entire stability assessment process is relatively cumbersome, and the technical and time costs are high. Summary of the invention

[0009] The present application aims to solve one of the technical problems in the related art at least to some extent.

[0010] To this end, the first purpose of this application is to propose a topology optimization and stability strength assessment method for a cantilever base assembly, which can simplify the cantilever base assembly while ensuring that the stress state of the structure remains unchanged, and realize the lightweight design of the cantilever base structure while ensuring that the structure meets the working requirements, and perform topology optimization design on the structure and stability strength assessment of the lightweight structure. This embodiment proposes a specific implementation plan for complete assembly structure simplification, lightweight design and strength assessment.

[0011] The second object of the present application is to provide a topology optimization and stability strength evaluation device for a cantilever-arm-base assembly.

[0012] To achieve the above-mentioned objectives, the first embodiment of the present application proposes a method for topological optimization and stability strength assessment of a cantilever base assembly, including: establishing a finite element model of the cantilever base assembly; simplifying the boundary conditions of independent key parts in the finite element model to obtain a simplified finite element model; selecting the area of ​​the independent key parts except for the areas where constraints and loads are applied as optimization objects, with the goal of minimizing the total variable performance of the structure under a given load, and with the volume fraction response as a constraint, obtaining a structural configuration with maximum stiffness through topological optimization; using the direct periodic method to perform stability strength assessment on the topologically optimized structural configuration to obtain a stability load.

[0013] Optionally, in one embodiment of the present application, establishing a finite element model of a cantilever-arm-base assembly includes:

[0014] The finite element meshing software HyperMesh is used to mesh the geometric model of the cantilever base assembly, analyze its force characteristics, and establish the finite element model of the cantilever base assembly;

[0015] The Interation module in Abaqus sets the contact properties of each part in the finite element model.

[0016] The method further includes:

[0017] The working load and constraints of the finite element model under standard working conditions are set, and the static simulation analysis of the finite element model under standard working conditions is performed to obtain the analysis results.

[0018] Optionally, in one embodiment of the present application, the process of simplifying the boundary conditions of independent key parts includes:

[0019] Determine the contact surface between the independent key parts and other parts, and set the set of surface nodes of the key parts contact surface to SET;

[0020] Open the analysis result file of the arm-base assembly under standard working conditions, extract the node information and node force of each node in SET, and save it in a mat format file;

[0021] Use Matlab to open the mat file and calculate the contact force of each node in the SET as the size of the external load required to be applied to each node corresponding to the independent key parts;

[0022] In Matlab, external loads are applied to the model by adding codes to the inp calculation file of the finite element model, and the applied working load is kept unchanged.

[0023] Optionally, in one embodiment of the present application, a direct periodic method is used to perform a shakedown strength assessment on the topology optimized structural configuration to obtain a shakedown load, including:

[0024] Establish direct periodic method analysis step, set analysis step size and increment;

[0025] Keeping the constraints unchanged, different cyclic loads are applied to the structure, and the peak load size is n times the elastic limit load;

[0026] The plastic dissipation work curve of the structure when the load is applied is obtained, and when the plastic dissipation work remains at 0, the corresponding load peak is determined as the shaking load.

[0027] To achieve the above-mentioned purpose, a second embodiment of the present invention provides a topology optimization and stability strength evaluation device for a cantilever-arm-base assembly, comprising:

[0028] Model building module, used to build the finite element model of the cantilever-arm-base assembly;

[0029] Model simplification module, used to simplify the boundary conditions of independent key parts in the finite element model to obtain a simplified finite element model;

[0030] The topology optimization module is used to select the area of ​​independent key parts except the area where constraints and loads are applied as the optimization object, with the goal of minimizing the total variable performance of the structure under a given load and the volume fraction response as a constraint, to obtain the structural configuration with maximum stiffness through topology optimization;

[0031] The shakedown strength assessment module is used to perform shakedown strength assessment on the structural configuration after topology optimization using the direct periodic method to obtain the shakedown load.

[0032] Optionally, in one embodiment of the present application, the model building module is specifically used to:

[0033] The finite element meshing software HyperMesh is used to mesh the geometric model of the cantilever base assembly, analyze its force characteristics, and establish the finite element model of the cantilever base assembly;

[0034] The Interation module in Abaqus sets the contact properties of each part in the finite element model.

[0035] The model building module is also used to:

[0036] The working load and constraints of the finite element model under standard working conditions are set, and the static simulation analysis of the finite element model under standard working conditions is performed to obtain the analysis results.

[0037] Optionally, in one embodiment of the present application, the process of simplifying the boundary conditions of independent key parts includes:

[0038] Determine the contact surface between the independent key parts and other parts, and set the set of surface nodes of the key parts contact surface to SET;

[0039] Open the analysis result file of the arm-base assembly under standard working conditions, extract the node information and node force of each node in SET, and save it in a mat format file;

[0040] Use Matlab to open the mat file and calculate the contact force of each node in the SET as the size of the external load required to be applied to each node corresponding to the independent key parts;

[0041] In Matlab, external loads are applied to the model by adding codes to the inp calculation file of the finite element model, and the applied working load is kept unchanged.

[0042] Optionally, in one embodiment of the present application, the shakedown strength assessment module is specifically used to:

[0043] Establish direct periodic method analysis step, set analysis step size and increment;

[0044] Keeping the constraints unchanged, different cyclic loads are applied to the structure, and the peak load size is n times the elastic limit load;

[0045] The plastic dissipation work curve of the structure when the load is applied is obtained, and when the plastic dissipation work remains at 0, the corresponding load peak is determined as the shaking load.

[0046] The topology optimization and stability strength assessment method of the arm-base assembly of the embodiment of the present application includes a boundary condition simplification method for the complex assembly of the arm-base assembly, and a topology optimization of simplified parts and components and an assembly strength assessment method based on the direct periodic method. This embodiment uses programming means to make the simplified model completely restore the effect of contact force on the parts and their stress state in the assembly, and then uses a topology optimization algorithm with stiffness as the target to obtain the basic configuration of the simplified model, and performs lightweight design on the structure. Finally, the direct periodic method is used to perform stability assessment on the strength of the assembly structure, thereby ensuring that the stiffness and strength of the lightweight structure meet the basic requirements.

[0047] Compared with traditional simplification methods, the method of simplifying a complex assembly structure into parts in the embodiment of the present application can not only avoid the stress concentration phenomenon caused by equivalent concentrated force, but also achieve the simplification of the arm base assembly while completely ensuring that the stress state of the structure remains unchanged. This method can solve the problem that during topological optimization of complex bow net component assemblies, a huge amount of calculation will be generated due to contact and other connection relationships, and the problem that it needs to be simplified into a single part.

[0048] The embodiment of the present application combines the direct periodic method with the stability method in the field of engineering applications. For a specific engineering parts assembly structure, a design method is formed that first optimizes the topology of key parts with stiffness as the target to obtain a lightweight configuration, and then uses the direct periodic method to check the stability strength of the assembly composed of key parts, thereby continuously adjusting and optimizing. Compared with other methods such as the incremental method, it not only has a simple process and saves time and cost, but also has higher accuracy and efficiency under high-cycle fatigue. This method can not only be used for the lightweight design of key parts in the arm-base assembly, but also serve the optimization and weight reduction of various complex assemblies.

[0049] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0051] Figure 1 A schematic flow chart of a topology optimization and stability strength evaluation method for a cantilever-base assembly provided in the first embodiment of the present application;

[0052] Figure 2 This is a schematic diagram of the structure of the arm-base assembly according to an embodiment of the present application;

[0053] Figure 3 A schematic diagram of a finite element model of the arm-base assembly structure of an embodiment of the present application;

[0054] Figure 4 It is a schematic diagram of loads and boundary conditions of a finite element model of the cantilever-base assembly structure of an embodiment of the present application under a 10 kN vertical load condition;

[0055] Figure 5 This is a cloud diagram of the structural stress field distribution of the cantilever base assembly structure of the embodiment of the present application under a 10kN vertical load condition;

[0056] Figure 6 It is a simplified schematic diagram of a single part from an assembly to a cantilever base body and a rotating flat double ear according to an embodiment of the present application;

[0057] Figure 7 A schematic diagram comparing the stress field distribution of the middle arm base body of the embodiment of the present application after being taken out for calculation separately and after being calculated in the assembly;

[0058] Figure 8 It is a schematic diagram of the topologically optimized configuration of the cantilever base body and the rotating flat double ears of an embodiment of the present application;

[0059] Fig. 9 A schematic diagram of the loading path in each cycle of the direct cycle method of an embodiment of the present application;

[0060] Fig.10 A schematic diagram of a curve showing the change of plastic dissipated work with load obtained by the direct periodic method according to an embodiment of the present application;

[0061] Fig.11 A schematic structural diagram of a topological optimization and stability strength assessment device for a cantilever-base assembly provided in an embodiment of the present application. DETAILED DESCRIPTION

[0062] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0063] The following describes the topology optimization and stability strength evaluation method and device of the cantilever-arm-base assembly of an embodiment of the present application with reference to the accompanying drawings.

[0064] Figure 1 A schematic flow chart of a topology optimization and stability strength evaluation method for a cantilever-base assembly provided in Example 1 of the present application.

[0065] like Figure 1 As shown, the topology optimization and stability strength evaluation method of the cantilever base assembly includes the following steps:

[0066] Step 101, establishing a finite element model of a cantilever-arm-base assembly;

[0067] In this embodiment, the commonly used arm-base assembly structure is used as a specific implementation object, and its structure is as follows: Figure 2 As shown, the main parts include a cantilever base body 1, a rotating flat double ear 2 and a pin 3, wherein the cantilever base is the main component in the assembly, and is fixed to the pillar by two fixing bolts through the elliptical holes at the bottom, and the rotating flat double ear is connected to the cantilever base by a pin through a matching pin hole, and its end is connected to other parts by another pin, and the load on the cantilever is transmitted to the rotating flat double ear by the pin, and then transmitted to the cantilever base by the rotating flat double ear through the pin.

[0068] In this embodiment, the finite element meshing software HyperMesh is used to mesh the geometric model of the cantilever-arm base assembly, analyze its force characteristics, and establish a finite element model of the cantilever-arm base assembly. Specifically, the process includes:

[0069] According to the geometric model of the cantilever-arm base assembly, the corresponding finite element model is established as follows: Figure 3As shown, since the fixing bolts and pins only play the role of constraint and load transfer in the model and are not the research object, they are simplified. The mesh unit type of the model is hexahedral unit, the mesh size is 2mm, the number of units of the arm base is 91640, the number of units of the pin is 17600, and the number of units of the rotating flat ears is 31312. The aspect ratio (Aspect) and warpage (Warpage) are used as indicators for mesh quality control. The aspect ratio of the final generated mesh is less than 5:1, and the warpage is less than 5 degrees. All unit types are first-order hexahedral reduced integration C3D8R units. In this embodiment, the material parameters of the finite element model are shown in Table 1:

[0070] Table 1 Material parameters of the parts of the cantilever base assembly

[0071] Young's modulus (Gpa) Poisson's ratio (-) Yield Strength(Mpa) Arm base 210 0.3 235 Rotating flat ears 210 0.3 235 Pin 210 0.3 355

[0072] In this embodiment, the contact properties of each part in the finite element model are set in the Interation module in Abaqus. Specifically, the contact settings between the parts in the arm-to-base assembly are as follows: the normal contact behavior is set to hard contact (Hard Contact), and the tangential contact behavior is set to a friction factor of 0.2. The contact pairs are the contact between the arm-to-base and the pin, and the contact between the pin and the rotating flat ears. The selection of the master and slave surfaces in the contact pair follows the following criteria: the surface with a coarser mesh is used as the master surface; when the mesh density is equivalent, the harder material is used as the master surface. In this model, in the contact pair between the arm-to-base and the pin, the arm-to-base is set as the master surface; in the contact pair between the pin and the rotating flat ears, the pin is set as the master surface. In addition, since there may be a certain gap or interference between the contact surfaces, the adjustment area tolerance is set to 0.02 in the slave surface adjustment module.

[0073] In this embodiment, during the static simulation analysis of the cantilever base assembly under the standard working condition, the load under the standard working condition is applied by creating a surface traction type load in the two upper pin holes of the rotating flat double ears in the Load module of Abaqus. The load is the load per unit area of ​​the inner surface of the pin hole. Specifically, the process includes:

[0074] According to the standard requirements, the maximum vertical working load of the cantilever base assembly is 10.0kN, and the maximum horizontal working load is 6.0kN. The load and constraint settings of the cantilever base assembly under the vertical working load of 10.0kN established according to the working conditions are as follows: Figure 4As shown in the figure, full constraints are applied to all nodes on the inner side of the two bolt fixing holes at the bottom of the cantilever base, and loads of equal magnitude and direction are applied to the contact surface of the pin holes connecting the rotating flat double ears with other parts. The resultant force is the working load. Taking a vertical load of 10kN as an example, a vertical load of 5kN is applied to the two pin holes of the rotating flat double ears respectively. The calculated stress cloud diagram of the cantilever base assembly under the maximum vertical working load is shown in the figure below. Figure 5 shown.

[0075] Step 102, simplifying the boundary conditions of independent key parts in the finite element model to obtain a simplified finite element model;

[0076] Since there are contact and other connection relationships in the arm-base assembly, topology optimization in the original model will generate a huge amount of calculation, so it is necessary to select independent key parts as optimization objects.

[0077] In this embodiment, in the process of extracting the node information of each node on the contact surface of the arm-base assembly in the calculation result file, it is necessary to open the odb calculation result file under the standard working condition of the arm-base assembly, and then run the Python program to extract the node number, unit number, node force and other information of the node set composed of each node on the contact surface. During the extraction process, the Matlab program is called to temporarily save the extraction results in the workspace. After the extraction is completed, the workspace is opened to save the data in mat format to complete the extraction of the node information in the calculation results.

[0078] In this embodiment, in the process of using Matlab program to process node information to obtain load size and apply it to the part model in batches, first open the saved mat file, save the data to the workspace, and then use the program to sum the node forces of adjacent units on each node to obtain the resultant force received by each node, that is, the size of the contact force received by each node on the contact surface, and save it in the form of (x, y, z), and finally ensure that each node number corresponds to the resultant force received. After obtaining the contact force of each node, it is necessary to apply it to the part model. Since the load applied in the model is reflected in the inp calculation file to add four lines of code in a specific format, the contact force can be applied to the model in batches and quickly by directly adding code in the inp calculation file of the part model. The specific operation is: using Matlab to generate a code that is unified with the inp calculation file, the code content is to establish a SET set for each node, and apply corresponding forces in three directions to each set, and finally export it to inp format, and paste the exported code into the calculation file of the part model.

[0079] In this embodiment, Figure 2Taking the arm base assembly of as an example, the specific simplification process is as follows: the arm base body is mainly subjected to the contact force of the pin in the pin hole, so the set of nodes on the inner surface of the pin hole is set as SET-1. After calculating the odb calculation result file under the standard working condition of the assembly, the Python program is used to extract the node information and node force NFORCE of each node in SET-1, save it in a mat format file, open this file with Matlab, and use the program to calculate and process the contact force of each node. At this time, the contact force of each node is the size of the external load required to be applied to each node in the part. Open ABAQUS to submit the inp file required for calculation, and apply the external load to the corresponding nodes in batches, so as to realize the simplification of the arm base assembly to the arm base body. Similarly, the rotating flat double ear is also mainly subjected to the contact force of the pin on the inner surface of the pin hole in the assembly. Therefore, Python and Matlab are used to jointly program the contact force of the pin on the rotating flat double ear as an external load applied to each node on the inner surface of the pin hole, and the applied working load is kept unchanged to realize the simplification of the model. Since constraints must be imposed in static simulation, and the contact force is converted into load and applied to the inner hole of the rotating flat double-ear, the structure is under force balance. Therefore, it is only necessary to impose a spring constraint with extremely small elasticity around the structure to limit its rigid displacement.

[0080] The simplification process of the arm base assembly is as follows Figure 6 As shown, the stress distribution of the simplified model is as follows Figure 7 By comparing the stress distribution in the assembly, it is found that the distribution of the stress field and the magnitude and position of the maximum stress value are basically consistent, indicating that the method of extracting the node force of the contact surface through Python programming, and then using Matlab programming to process the load and insert it into the inp file to realize the transformation of the contact problem into the load problem is reasonable.

[0081] Step 103, selecting the area of ​​the independent key parts except the area where the constraints and loads are applied as the optimization object, taking the minimum total variable performance of the structure under the given load as the goal, taking the volume fraction response as the constraint, and obtaining the structural configuration with the maximum stiffness through topology optimization;

[0082] In this embodiment, the arm base body and the rotating flat double ears are regarded as independent key parts.

[0083] In this embodiment, referring to the relevant technical standards, the maximum vertical working load of the cantilever base body is 10.0kN, and the maximum horizontal working load is 6.0kN. Therefore, the area where the cantilever base applies constraints and loads is frozen, and the constrained design domain volume is 70% of the original. The topology optimization model is established with the goal of minimizing the strain energy of the cantilever base under the standard working condition of 10.0kN vertical load and 6.0kN horizontal load. The optimization objective function and constraint conditions are as follows:

[0084] min:f(x)=U T KU

[0085]

[0086] Since the optimization requires a large number of iterative calculations and the SIMP algorithm has a high iterative efficiency, the SIMP algorithm is used for topology optimization, where the penalty factor p is set to 3.

[0087] The final topology optimization configuration obtained by constraining the design domain volume to be 70% of the original one is as follows: Figure 8 As shown in the figure, since the variable density method, a topology optimization algorithm, achieves structural optimization by changing the unit density, the final optimized configuration retains units with a relative density between 0.001 and 1.

[0088] Step 104, using the direct periodic method to perform a shakedown strength assessment on the topology optimized structural configuration to obtain a shakedown load.

[0089] In this embodiment, the direct periodic method is used to perform a stability strength assessment on the cantilever base assembly after topology optimization. The direct periodic method analysis step is established, and a reasonable analysis step size and increment are set. The constraints are kept unchanged, and different cyclic loads are applied to the structure. The load peak value is n times the elastic limit load. The plastic dissipated work curve of the assembly structure is observed. When the plastic dissipated work is always 0, the corresponding load peak value is the stability load of the cantilever base assembly.

[0090] In this embodiment, the direct period method belongs to direct shakedown analysis, which directly calculates the cyclic stability response of the structure under cyclic loading by combining the time integral of nonlinear materials and Fourier series. When the structure reaches a stable mechanical response under cyclic loading, the displacement will show periodic changes in subsequent cyclic loading. According to this principle, the displacement function in the structure is expressed by Fourier series as:

[0091]

[0092] Where: u(t) represents the displacement function at all times t in a load cycle with a period of T, u0 is a constant term, n is the number of Fourier terms, and are the coefficients of the cosine and sine terms respectively, and w=2π / T is the angular frequency.

[0093] Similarly, the solution process of the nonlinear overall equilibrium equation can be expanded into the same form as the displacement function, as shown below:

[0094] R(t)=F(t)-I(t)

[0095]

[0096] Where: R(t) is the residual vector, F(t) represents the external force at all times t in a load cycle with a period of T, I(t) is the internal force vector, and R0 is the constant term. and are the coefficients of the cosine and sine terms respectively.

[0097] The coefficients are assembled as follows:

[0098]

[0099] The following two formulas are two criteria for judging whether convergence occurs:

[0100]

[0101] Where: is the maximum permissible ratio of the maximum residual coefficient in the Fourier series to the corresponding mean flux norm, It is the maximum allowable ratio of the maximum displacement coefficient correction to the maximum displacement coefficient in the Fourier series.

[0102] When the convergence criterion is not met, it is necessary to perform continuous iterations to correct the displacement Fourier coefficients while ensuring that all mechanical quantities meet the periodicity. Finally, the displacement coefficient obtained after the (i)th iteration is correct in the (i+1)th iteration. If convergence does not occur during the iteration process, it means that the structure has plastic ratcheting cyclic behavior, that is, the structure does not meet the strength requirements. The update formula of the displacement Fourier coefficient is as follows:

[0103]

[0104] Where: c0 is the correction term of the constant term, are correction terms for the periodic terms. These correction terms can be solved by the following equations:

[0105]

[0106]

[0107] Where: K is the elastic stiffness matrix.

[0108] In this example, the theoretical basis of the direct cycle method is used to verify whether the arm-base assembly structure is stable, so as to obtain the stable load of the structure. The specific operations are as follows: a finite element model of the arm-base assembly after topology optimization is established in the Abaqus finite element simulation software, and its elastic-plastic material parameters are assigned. In the Step module of the Abaqus finite element simulation software, a direct cycle analysis step is created, and the appropriate cycle time, step size and increment are set. Specifically, the total step length of the analysis step Cycle time period is 2, the maximum number of increments Max of increments is 1000000, and the increment size Increment size is 0.05. Keeping the constraint and contact settings unchanged, set the loading amplitude curve of each cycle in the Load module to simulate the process of the structure being subjected to cyclic loads, where the load peak is set to 4 times the elastic limit load of 40kN, the time span Time span is selected as step time, the load smoothing is set to 0, the time and amplitude are: 0,0; 1,1; 2,0, respectively, and the loading path is as follows: Fig. 9 After submitting the calculation, the plastic dissipation work curve of the assembly structure in one load cycle after the structure is stable under cyclic loads with different peak values ​​is extracted. Specifically, the plastic dissipation work data in the process output is extracted for processing and analysis, and the change curve of the plastic dissipation work value in one cycle after the structure is stable with the load loading is drawn as shown in Fig.10 shown.

[0109] In this example, the plastic dissipation work curve is analyzed. It can be seen that as the load changes continuously within a cycle, the plastic dissipation work of the stabilized structure is always 0 throughout the cycle, indicating that no new plastic deformation occurs during the loading cycle after the structure is stabilized, and the structure is in a stable state, indicating that 40kN is the vertical stability load of the optimized cantilever base assembly.

[0110] In this example, the shakedown analysis process of the arm-base assembly under horizontal working conditions is the same as above. If the plastic dissipated work of the structure is not always 0 when the structure is stable after applying n times the elastic limit load, it means that the structure has plastic ratcheting cyclic behavior and has not reached a stable state. At this time, the load size needs to be reduced until the plastic dissipated work of the stabilized structure is always 0 throughout the entire cycle. At this time, the shakedown load of the structure can be obtained.

[0111] The topology optimization and stability strength assessment method of the arm base assembly proposed in this embodiment combines topology optimization with the stability theory based on the direct periodic method to form a lightweight design method suitable for complex assembly structures, from simplifying the assembly, determining the topology optimization configuration with stiffness as the target, to verifying the stability state of the optimized configuration with the direct periodic method as the stability strength assessment method, and determining the stability load. This method can not only be used for the lightweight design of the contact network arm base assembly, but also can serve the optimization and weight reduction of other complex bow-net assembly structures.

[0112] In order to implement the above-mentioned embodiments, the present application also proposes a topology optimization and stability strength evaluation device for a cantilever-arm-base assembly.

[0113] Fig.11 A schematic structural diagram of a topological optimization and stability strength assessment device for a cantilever-base assembly provided in an embodiment of the present application.

[0114] like Fig.11 As shown, the topology optimization and stability strength evaluation device of the cantilever base assembly includes:

[0115] Model building module, used to build the finite element model of the cantilever-arm-base assembly;

[0116] Model simplification module, used to simplify the boundary conditions of independent key parts in the finite element model to obtain a simplified finite element model;

[0117] The topology optimization module is used to select the area of ​​independent key parts except the area where constraints and loads are applied as the optimization object, with the goal of minimizing the total variable performance of the structure under a given load and the volume fraction response as a constraint, to obtain the structural configuration with maximum stiffness through topology optimization;

[0118] The shakedown strength assessment module is used to perform shakedown strength assessment on the structural configuration after topology optimization using the direct periodic method to obtain the shakedown load.

[0119] Optionally, in one embodiment of the present application, the model building module is specifically used to:

[0120] The finite element meshing software HyperMesh is used to mesh the geometric model of the cantilever base assembly, analyze its force characteristics, and establish the finite element model of the cantilever base assembly;

[0121] The Interation module in Abaqus sets the contact properties of each part in the finite element model.

[0122] The model building module is also used to:

[0123] The working load and constraints of the finite element model under standard working conditions are set, and the static simulation analysis of the finite element model under standard working conditions is performed to obtain the analysis results.

[0124] Optionally, in one embodiment of the present application, the process of simplifying the boundary conditions of independent key parts includes:

[0125] Determine the contact surface between the independent key parts and other parts, and set the set of surface nodes of the key parts contact surface to SET;

[0126] Open the analysis result file of the arm-base assembly under standard working conditions, extract the node information and node force of each node in SET, and save it in a mat format file;

[0127] Use Matlab to open the mat file and calculate the contact force of each node in the SET as the size of the external load required to be applied to each node corresponding to the independent key parts;

[0128] In Matlab, external loads are applied to the model by adding codes to the inp calculation file of the finite element model, and the applied working load is kept unchanged.

[0129] Optionally, in one embodiment of the present application, the shakedown strength assessment module is specifically used to:

[0130] Establish direct periodic method analysis step, set analysis step size and increment;

[0131] Keeping the constraints unchanged, different cyclic loads are applied to the structure, and the peak load size is n times the elastic limit load;

[0132] The plastic dissipation work curve of the structure when the load is applied is obtained, and when the plastic dissipation work remains at 0, the corresponding load peak is determined as the shaking load.

[0133] It should be noted that the above explanation of the embodiment of the method for topological optimization and stability strength evaluation of the arm-base assembly is also applicable to the topological optimization and stability strength evaluation device of the arm-base assembly of this embodiment, and will not be repeated here.

[0134] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0135] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0136] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0137] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute the instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0138] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0139] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0140] In addition, each functional unit in each embodiment of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0141] The storage medium mentioned above may be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application. A person of ordinary skill in the art may change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for topological optimization and stability strength evaluation of a cantilever-arm-base assembly, characterized in that: include: Establish the finite element model of the cantilever-arm-base assembly; Simplifying the boundary conditions of independent key parts in the finite element model to obtain a simplified finite element model; The area except the area where constraints and loads are applied in independent key parts is selected as the optimization object, with the goal of minimizing the total variable performance of the structure under a given load, and the volume fraction response as a constraint, and the structural configuration with maximum stiffness is obtained through topology optimization; The direct periodic method is used to evaluate the stability of the structural configuration after topology optimization and obtain the stability load.

2. The method according to claim 1, characterized in that The step of establishing a finite element model of the cantilever-arm-base assembly includes: The finite element meshing software HyperMesh is used to mesh the geometric model of the cantilever base assembly, analyze its force characteristics, and establish the finite element model of the cantilever base assembly; The Interation module in Abaqus sets the contact properties of each part in the finite element model. The method further comprises: The working load and constraint of the finite element model under the standard working condition are set, and the static simulation analysis of the finite element model under the standard working condition is performed to obtain the analysis result.

3. The method according to claim 2, characterized in that The simplification process of boundary conditions for independent key parts includes: Determine the contact surface between the independent key parts and other parts, and set the set of surface nodes of the key parts contact surface to SET; Open the analysis result file of the arm-base assembly under standard working conditions, extract the node information and node force of each node in SET, and save it in a mat format file; Open the mat file using Matlab, and calculate the contact force of each node in the SET as the size of the external load required to be applied to each corresponding node in the independent key part; In Matlab, external loads are applied to the model by adding codes to the inp calculation file of the finite element model, and the applied working load is kept unchanged.

4. The method according to claim 1, characterized in that The direct periodic method is used to evaluate the stability of the structural configuration after topology optimization to obtain the stability load, including: Establish direct periodic method analysis step, set analysis step size and increment; Keeping the constraints unchanged, different cyclic loads are applied to the structure, and the peak load size is n times the elastic limit load; The plastic dissipation work curve of the structure when the load is applied is obtained, and when the plastic dissipation work remains at 0, the corresponding load peak is determined as the shaking load.

5. A topology optimization and stability strength evaluation device for a cantilever-base assembly, characterized in that: include: Model building module, used to build the finite element model of the cantilever-arm-base assembly; A model simplification module, used to simplify the boundary conditions of independent key parts in the finite element model to obtain a simplified finite element model; The topology optimization module is used to select the area of ​​independent key parts except the area where constraints and loads are applied as the optimization object, with the goal of minimizing the total variable performance of the structure under a given load and the volume fraction response as a constraint, to obtain the structural configuration with maximum stiffness through topology optimization; The shakedown strength assessment module is used to perform shakedown strength assessment on the structural configuration after topology optimization using the direct periodic method to obtain the shakedown load.

6. The device according to claim 5, characterized in that The model building module is specifically used for: The finite element meshing software HyperMesh is used to mesh the geometric model of the arm base assembly and analyze its force characteristics. Establish the finite element model of the cantilever-arm-base assembly; The Interation module in Abaqus sets the contact properties of each part in the finite element model. The model building module is also used for: The working load and constraint of the finite element model under the standard working condition are set, and the static simulation analysis of the finite element model under the standard working condition is performed to obtain the analysis result.

7. The device according to claim 6, characterized in that The simplification process of boundary conditions for independent key parts includes: Determine the contact surface between the independent key parts and other parts, and set the set of surface nodes of the key parts contact surface to SET; Open the analysis result file of the arm-base assembly under standard working conditions, extract the node information and node force of each node in SET, and save it in a mat format file; Open the mat file using Matlab, and calculate the contact force of each node in the SET as the size of the external load required to be applied to each corresponding node in the independent key part; In Matlab, external loads are applied to the model by adding codes to the inp calculation file of the finite element model, and the applied working load is kept unchanged.

8. The device according to claim 5, characterized in that The shakedown strength assessment module is specifically used for: Establish direct periodic method analysis step, set analysis step size and increment; Keeping the constraints unchanged, different cyclic loads are applied to the structure, and the peak load size is n times the elastic limit load; The plastic dissipation work curve of the structure when the load is applied is obtained, and when the plastic dissipation work remains at 0, the corresponding load peak is determined as the shaking load.

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