Aerial rudder lightweight design method for partition dot matrix filling

Abstract

The invention discloses a partition dot matrix filling air rudder lightweight design method. The method mainly comprises three parts of establishment of a dot matrix unit cell equivalent mechanical performance proxy model, topological optimization design of an air rudder structure and optimization design of dot matrix filling parameters. Comparing compression tests of different rod diameters with simulation results of variable cross-section beam units with different parameters, and searching optimal beam unit cross-section parameters to construct and calculate a lattice unit cell equivalent mechanical performance agent model; structure topological optimization design is carried out on the determined air rudder appearance and load conditions, dot matrix filling area division is carried out on a design area according to a topological optimization result, and the design area can be divided into areas with different filling densities according to design requirements; and establishing a parameterized finite element model for the dot matrix filling structure and the air rudder model, and performing optimization design on rod diameters of different partitions on the basis to obtain a final dot matrix filling design model.

Description

TECHNICAL FIELD

[0001] The application relates to a partitioned lattice filling air vane lightweight design method and relates to the technical field of aerospace structure design. BACKGROUND

[0002] The air vane is an important component of the aircraft and is a key component for controlling the flight of the aircraft. With the improvement of the requirements for the flight speed, the voyage and the maneuvering performance of the aircraft such as a missile, the air vane faces more complex external load conditions. Meanwhile, higher requirements are put forward for the further lightweight design of the air vane. The traditional topology optimization design method mainly adopts the skin-skeleton form, but the overall weight reduction effect is limited.

[0003] Compared with the traditional method, the design method combining additive manufacturing and lattice structure has great advantages in lightweight design. On the one hand, the additive manufacturing technology is easy to realize the integrated design of the structure and is outstanding in the manufacturing capacity of complex parts. On the other hand, the superior mechanical properties of the lattice structure can greatly reduce the weight of the structure while ensuring the structural strength. Meanwhile, the internal space of the lattice structure can be used for functional design such as heat transfer.

[0004] A kind of air engine fan blade lattice filling method with Chinese patent publication No. CN112069623B can be according to engine fan blade topology optimization result carries out lattice filling partition design, but due to the uncertainty of additive manufacturing process, the equivalent mechanical properties of lattice structure have uncertainty; A kind of air vane surface based on 3D printing process of structure function integration with Chinese patent publication No. CN115180120A, this method combines lattice structure and variable thickness skin, realizes air vane structure lightweight and mass and stiffness distribution adjustable, but the patent does not involve air vane design and simulation optimization method. SUMMARY

[0005] The technical problem to be solved by the application is to overcome the shortcomings of the prior art, and provide a partitioned lattice filling air vane lightweight design method, and solve the problem of uncertainty of equivalent mechanical properties of lattice structure.

[0006] The purpose of the application is achieved by the following technical solutions:

[0007] A lightweight design method for a lattice-filled air rudder mainly includes three parts: establishing a surrogate model of equivalent mechanical performance of the lattice unit cell, topology optimization design of the air rudder structure, and optimization design of lattice filling parameters. This invention compares compression tests with beam element simulations using different rod diameters and varying cross-sections to find the optimal beam element cross-section parameters and construct a surrogate model for calculating the equivalent mechanical performance of the lattice unit cell. For a given air rudder shape and load conditions, topology optimization design is performed. Based on the topology optimization results, the design area is divided into lattice-filled regions, which can be divided into regions with different filling densities according to design needs. A parametric finite element model is established for the lattice-filled structure and the air rudder model. Based on this, the rod diameters of different zones are optimized to obtain the final lattice-filled design model. This invention, through experimental data and the establishment of a variable cross-section beam model, can achieve accurate prediction of the mechanical properties of lattice-filled air rudders, avoiding the influence of additive manufacturing process uncertainties on structural strength verification, and directly obtaining the stress state of each unit cell member. In addition, non-homogeneous lattice filling can be achieved by partitioned lattice filling, which can be done using 3D lattice filling software. This eliminates the need for extensive model processing and facilitates rapid and lightweight design of aerodynamic rudders in engineering projects.

[0008] In a first aspect, the present invention provides a lightweight design method for an aerodynamic rudder with partitioned dot matrix filling, comprising:

[0009] Step 1: Establish a surrogate model for the equivalent mechanical properties of a lattice unit cell, specifically including:

[0010] S100: Determine the diameter of the compression test rod to be 3D printed according to the selected lattice unit cell type;

[0011] S101: Conduct a static compression test based on the diameter of the compression specimen rod;

[0012] S102: Establish a parametric beam element finite element model corresponding to the compression specimen, and select different beam element section parameters to carry out compression simulation calculations so that the calculation results of the selected parameters are consistent with the experimental results;

[0013] S103: Establish a unit cell equivalent mechanical performance proxy model based on the beam element section parameters with different bar diameters obtained in S102;

[0014] Step 2: Perform topology optimization design on the aerodynamic rudder structure, specifically including:

[0015] S200: Establish the finite element model of the air rudder based on the load conditions, boundary conditions, and structural design domain of the air rudder;

[0016] S201: Based on the finite element model in S200, structural topology optimization design is carried out to obtain the material distribution within the design domain;

[0017] S202: Based on the material distribution within the design domain in S201, the design domain is divided into partitions, and each region is filled with lattice structure unit cells of different densities.

[0018] S203: Based on the partitioning results of S202, vertical partitions are built between different partitions; the partitions are perforated at intervals for powder discharge and heat dissipation;

[0019] Step 3: Optimize the dot matrix filling parameters to generate the final model, which includes:

[0020] S300: Based on the air rudder determined in S203, establish a parametric finite element model of the partitioned lattice-filled skin structure based on the variable cross-section beam model, and specify the initial rod diameter distribution;

[0021] S301: Optimize bar diameter parameters based on parametric finite element model, and use the surrogate model in S103 to correct the parametric finite element model;

[0022] S302: Reconstruct the optimized results and generate the final model in the 3D printing software.

[0023] Secondly, the present invention provides an air rudder with partitioned dot matrix filling, wherein the air rudder structure is determined by the air rudder lightweight design method described in the first aspect.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] (1) The method of the present invention establishes a proxy model of the equivalent mechanical properties of lattice structure unit cell based on compression test data, taking into account the uncertainties related to 3D printing process.

[0026] (2) This invention solves the problem of uncertainty in the equivalent mechanical properties of lattice structures by using a variable cross-section beam model and establishing a proxy model, and can directly obtain the stress situation of each rod of the lattice structure in the simulation calculation.

[0027] (3) Based on the compression test data, the present invention obtains the equivalent mechanical performance proxy model of the lattice unit cell, and then obtains the lightweight design result of the partitioned lattice-filled air rudder through topology optimization and parameter optimization, thus realizing the lightweight design of the lattice-filled air rudder.

[0028] (4) The method of the present invention can quickly realize the heterogeneous filling of the lattice structure and realize the refined finite element strength simulation analysis, avoiding the complex model processing process and making the lightweight design more efficient. Attached Figure Description

[0029] Figure 1 This is a flowchart of the method of the present invention;

[0030] Figure 2This is a finite element model of a variable cross-section beam element for a compression specimen, as described in an embodiment of the present invention.

[0031] Figure 3 This is a graph comparing the test results and simulation results of the compression specimens in an embodiment of the present invention.

[0032] Figure 4 This is the design result of a dot-matrix-filled air rudder in an embodiment of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0034] A lightweight design method for aerodynamic rudders with partitioned lattice filling, such as Figure 1 As shown, it includes:

[0035] Step 1: Establish a surrogate model for the equivalent mechanical properties of lattice unit cells

[0036] S100: Determine the diameter of the compression test rod to be 3D printed according to the selected lattice unit cell type;

[0037] S101: Based on the diameter of the compression test bar, print two test bars for each bar diameter and conduct static compression tests.

[0038] S102: Establish a parametric beam element finite element model corresponding to the compression specimen, and select different beam element section parameters to carry out compression simulation calculations so that the calculation results of the selected parameters are consistent with the experimental results;

[0039] S103: Establish a unit cell equivalent mechanical performance proxy model based on the beam element section parameters with different bar diameters obtained in S102;

[0040] Step 2: Topology optimization design of air rudder structure

[0041] S200: Establish the finite element model of the air rudder based on the load conditions, boundary conditions, and structural design domain of the air rudder;

[0042] S201: Based on the finite element model in S200, structural topology optimization design is carried out to obtain the material distribution within the design domain;

[0043] S202: Based on the material distribution within the design domain in S201, the design domain is divided into partitions, and each region is filled with lattice structure unit cells of different densities.

[0044] S203: Based on the partitioning results of S202, vertical partitions are built between different partitions to avoid connectivity issues between unit cells of different rod diameters; the partitions are perforated at intervals for powder discharge and heat dissipation;

[0045] Step 3: Optimization design of dot matrix filling parameters

[0046] S300: Based on the air rudder structure determined in step 203, establish a parametric finite element model of the partitioned lattice-filled skin structure based on the variable cross-section beam model, and specify the initial rod diameter distribution;

[0047] S301: Optimize bar diameter parameters based on parametric finite element model, and use the surrogate model in S103 to correct the finite element model;

[0048] S302: Perform CAD reconstruction on the optimized results and generate the final model in 3D printing software.

[0049] In step S100, the diameter of the compression test rod to be 3D printed is generally taken in 4-8 groups at equal intervals, ranging from the minimum printing rod diameter in additive manufacturing to 0.2 times the unit cell size.

[0050] In step S101, the compression direction of the static compression specimen test is consistent with the printing direction.

[0051] In the parametric beam element finite element model in step S102, the beam is generally divided into three segments. The beam elements at both ends near the connection and the beam elements in the middle segment are defined with different cross-sectional properties.

[0052] The single-cell equivalent biomechanical performance proxy model in step S103 adopts a polynomial proxy model.

[0053] The structural design domain in step S200 includes all areas except for the air rudder skin and rudder mounting position.

[0054] The optimization formula in the structural topology optimization in step S201 is:

[0055]

[0056] Where ω2 is the first-order bending frequency of the aerodynamic rudder, ω1 is the first-order torsional frequency, K is the structural stiffness matrix, and M is the structural mass matrix. For the j-th frequency corresponding mode, ρ e V is the density of the e-th element as defined by the variable density method. e Let Ve be the volume of the e-th element, N be the total number of elements, V0 be the total volume of the calculated structural design domain, α be the desired volume fraction ratio, and t be the structural dimensional parameter. min With t max These represent the minimum and maximum values ​​of the dimensional constraints, ρ. min With ρ max These represent the minimum and maximum values ​​of the unit density, respectively.

[0057] The design domain partitioning in step S202 is generally divided into three categories: high-density area, medium-density area and low-density area.

[0058] The parameter optimization formula in step S301 is as follows:

[0059]

[0060] Where m is the total mass of the air rudder, K is the structural stiffness matrix, U is the structural displacement vector, F is the structural external force vector, and σ max σ0 is the maximum stress of the structure, σ0 is the allowable stress of the material, and d is the diameter of the lattice unit cell rod. min With d max These represent the minimum and maximum values ​​of the lattice unit cell diameter, respectively, and α. i The angle between the rib and the printing direction.

[0061] Example:

[0062] like Figure 1 A flowchart of the method of the present invention is provided. Figure 2 A finite element model of a variable cross-section beam element for a compression specimen is presented. Figure 3 This is a graph comparing the test results and simulation results of the compression specimen. Figure 4 The design results are shown for a lattice-filled air rudder. This invention provides a lightweight design method for a partitioned lattice-filled air rudder, mainly comprising three parts: establishing a surrogate model of equivalent mechanical performance of the lattice unit cell, optimizing the topology of the air rudder structure, and optimizing the lattice filling parameters. The specific steps are as follows:

[0063] Step 1: Establishment of a surrogate model for the equivalent mechanical performance of lattice unit cells

[0064] S100: Determine the diameter of the compression test rod to be 3D printed according to the selected lattice unit cell type; take 4 groups of compression test rod diameters at equal intervals from the minimum printing rod diameter in additive manufacturing to 0.2 times the unit cell size.

[0065] S101: Based on the diameter of the compression test bar, print two test bars for each bar diameter and conduct static compression tests; the compression direction in the static compression test is the same as the printing direction.

[0066] S102: Establish a parametric beam element finite element model corresponding to the compression specimen, and select different beam element section parameters to carry out compression simulation calculations so that the calculation results of the selected parameters are consistent with the test results; in the parametric beam element finite element model, the beam is divided into three segments, and the beam elements at both ends of the member near the connection and the beam elements in the middle segment are defined with different section properties;

[0067] S103: Based on the beam element section parameters with different beam diameters obtained in S102, establish a unit cell equivalent mechanical performance proxy model; the unit cell equivalent mechanical performance proxy model adopts a polynomial proxy model;

[0068] Step 2: Topology optimization design of air rudder structure

[0069] S200: Based on the load conditions, boundary conditions, and structural design domain of the air rudder, establish the finite element model of the air rudder; the structural design domain is all areas except for the air rudder skin and the rudder mounting position.

[0070] S201: Based on the finite element model in S200, structural topology optimization design is carried out to obtain the material distribution within the design domain;

[0071] S202: Based on the material distribution within the design domain in S201, the design domain is partitioned, with each region filled with lattice structural unit cells of different densities; the optimization formula in the structural topology optimization is as follows:

[0072]

[0073] Where ω2 is the first-order bending frequency of the aerodynamic rudder, ω1 is the first-order torsional frequency, K is the structural stiffness matrix, and M is the structural mass matrix. For the j-th frequency corresponding mode, ρ e V is the density of the e-th element as defined by the variable density method. e The volume of the e-th element, N is the total number of elements, V0 is the total volume of the calculated structural design domain, α is the desired volume fraction ratio, taken as 0.2, and t is the structural dimension parameter. min With t max These are the minimum and maximum values ​​of the dimensional constraints, taken as 20mm and 40mm respectively, ρ min With ρ max These are the minimum and maximum values ​​of the unit density, respectively, taken as 0.001 and 1;

[0074] S203: Based on the partitioning results of S202, vertical partitions are built between different partitions to avoid connectivity issues between unit cells of different rod diameters; the partitions are perforated at intervals for powder discharge and heat dissipation; the design domain is divided into three categories: high-density zone, medium-density zone and low-density zone.

[0075] Step 3: Optimization design of dot matrix filling parameters

[0076] S300: Establish a parametric finite element model of a partitioned lattice-filled skin structure based on a variable cross-section beam model, and specify the initial bar diameter distribution;

[0077] S301: Based on the air rudder structure determined in step 203, optimize the rod diameter parameters using the parametric finite element model, and correct the finite element model using the surrogate model from S103; the parameter optimization formula is as follows:

[0078]

[0079] Where m is the total mass of the air rudder, K is the structural stiffness matrix, U is the structural displacement vector, F is the structural external force vector, and σ max σ0 is the maximum stress of the structure, σ0 is the allowable stress of the material, and d is the diameter of the lattice unit cell rod. min With d max These represent the minimum and maximum diameters of the lattice unit cell, respectively, taken as 0.5 mm and 1.5 mm, α i The angle between the rib and the printing direction is set to 45°.

[0080] S302: Perform CAD reconstruction on the optimized results and generate the final model in 3D printing software.

[0081] The contents not described in detail in this specification are common knowledge to those skilled in the art.

[0082] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A lightweight design method for aerodynamic rudders with partitioned dot matrix filling, characterized in that, include: Step 1: Establish a surrogate model for the equivalent mechanical properties of a lattice unit cell, specifically including: S100: Determine the diameter of the compression test rod to be 3D printed according to the selected lattice unit cell type; S101: Conduct a static compression test based on the diameter of the compression specimen rod; S102: Establish a parametric beam element finite element model corresponding to the compression specimen, and select different beam element section parameters to carry out compression simulation calculations so that the calculation results of the selected parameters are consistent with the experimental results; S103: Establish a unit cell equivalent mechanical performance proxy model based on the beam element section parameters with different bar diameters obtained in S102; Step 2: Perform topology optimization design on the aerodynamic rudder structure, specifically including: S200: Establish the finite element model of the air rudder based on the load conditions, boundary conditions, and structural design domain of the air rudder; S201: Based on the finite element model in S200, structural topology optimization design is carried out to obtain the material distribution in the design domain; S202: Based on the material distribution within the design domain in S201, the design domain is divided into partitions, and each region is filled with lattice structure unit cells of different densities; S203: Based on the partitioning results of S202, vertical partitions are built between different partitions; the partitions are perforated at intervals for powder discharge and heat dissipation; Step 3: Optimize the dot matrix filling parameters to generate the final model, which includes: S300: Based on the air rudder determined in S203, establish a parametric finite element model of the partitioned lattice-filled skin structure based on the variable cross-section beam model, and specify the initial rod diameter distribution; S301: Optimize bar diameter parameters based on parametric finite element model, and use the surrogate model in S103 to correct the parametric finite element model; S302: Reconstruct the optimized results and generate the final model in the 3D printing software.

2. The lightweight air rudder design method according to claim 1, characterized in that, In S100, multiple sets of compression test bar diameters for 3D printing are selected at equal intervals from the minimum additive manufacturing bar diameter to a predetermined size, and two test bars are printed for each bar diameter.

3. The lightweight air rudder design method according to claim 1, characterized in that, In the static compression test of S101, the compression direction is consistent with the printing direction.

4. The lightweight air rudder design method according to claim 1, characterized in that, In the parametric beam element finite element model in S102, the beam is divided into three segments. The beam elements at both ends near the connection and the beam elements in the middle segment are defined with different cross-sectional properties.

5. The lightweight air rudder design method according to claim 1, characterized in that, The single-cell equivalent biomechanical performance proxy model in S103 adopts a multinomial proxy model.

6. The lightweight air rudder design method according to claim 1, characterized in that, The structural design domain in S200 includes all areas except for the air rudder skin and rudder mounting location.

7. The lightweight air rudder design method according to claim 1, characterized in that, The optimization formula in the structural topology optimization in step S201 is as follows: Where ω2 is the first-order bending frequency of the aerodynamic rudder, ω1 is the first-order torsional frequency, K is the structural stiffness matrix, and M is the structural mass matrix. For the j-th frequency corresponding mode, ρ e V is the density of the e-th element as defined by the variable density method. e Let Ve be the volume of the e-th element, N be the total number of elements, V0 be the total volume of the calculated structural design domain, α be the desired volume fraction ratio, and t be the structural dimensional parameter. min With t max These represent the minimum and maximum values ​​of the dimensional constraints, ρ. min With ρ max These represent the minimum and maximum values ​​of the unit density, respectively.

8. The lightweight air rudder design method according to claim 1, characterized in that, The design domain partitioning in S202 is divided into three categories: high-density area, medium-density area, and low-density area.

9. The lightweight air rudder design method according to claim 1, characterized in that, The parameter optimization formula in S301 is as follows: Where m is the total mass of the air rudder, K is the structural stiffness matrix, U is the structural displacement vector, F is the structural external force vector, and σ max σ0 is the maximum stress of the structure, σ0 is the allowable stress of the material, and d is the diameter of the lattice unit cell rod. min With d max These represent the minimum and maximum values ​​of the lattice unit cell diameter, respectively, and α. i The angle between the rib and the printing direction.

10. An air rudder filled with a partitioned dot matrix, characterized in that, The air rudder structure is determined using the lightweight air rudder design method described in claim 1.

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