A structural optimization method for aircraft precooler connectors based on topology optimization

Abstract

The present invention discloses a structural optimization method for aircraft precooler connectors based on topological optimization, which can reduce the weight of parts while meeting performance requirements. According to the functional requirements and external loads of the precooler connector, mechanical analysis and modal analysis are performed on the pre-processing model to obtain its stress and deformation areas; then, the deformation and stress areas are set as non-optimizable areas, and the remaining parts are optimizable areas, and the optimizable areas are topologically optimized; the obtained optimized model is three-dimensionally reconstructed, and mechanical analysis and modal analysis are performed to verify whether it meets the design requirements. If it meets the design requirements, the aircraft precooler connector after weight reduction is obtained. Otherwise, according to the mechanical analysis results, the optimization constraints (i.e., mass percentage) of the secondary topological optimization or the three-dimensional reconstruction design scheme are adjusted, and the design is redesigned to finally obtain a lightweight structural part that meets the use requirements.

Description

Technical Field

[0001] The invention relates to the technical field of structural optimization, and in particular to an optimization method for an aircraft precooler connector based on topology optimization. Background Art

[0002] Topology optimization technology is one of the main development directions in the field of structural design. After topology optimization design, structural parts can not only meet their performance requirements, but also achieve lightweight design goals. For structural parts on aircraft, lightweighting can bring lower fuel consumption, higher capacity and a series of green economic benefits while ensuring performance and safety. Aircraft precooler connectors are mainly used to support the aircraft's precooler and air conditioning exhaust ducts, which are subject to various forces and torques under normal working conditions. Therefore, its design needs to ensure a certain strength while avoiding resonance.

[0003] At present, the aircraft precooler connectors are relatively expensive to purchase and have high manufacturing costs. It is necessary to reduce their design and production costs while meeting their usage requirements, which puts higher demands on their design. Summary of the invention

[0004] The present invention mainly aims at the deficiencies of the existing design and proposes a structural optimization method for aircraft precooler connectors based on topology optimization, which can shorten the design cycle and reduce the purchase-to-flight ratio and production manufacturing costs.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for optimizing the structure of an aircraft precooler connector based on topology optimization comprises the following steps:

[0007] Step 1, according to the functional requirements and external loads of the precooler connector, the pre-processing model is subjected to mechanical analysis and modal analysis to obtain the stress and deformation areas of the pre-processing model;

[0008] Step 2, setting the deformation and stress areas of the pre-processed model as non-optimizable areas, and setting the rest of the pre-processed model as optimizable areas;

[0009] Step 3, meshing the model after setting the non-optimizable area and the optimizable area;

[0010] Step 4, perform a topology optimization on the optimizable area to obtain a topology optimization model;

[0011] Step 5, judging whether the connection and force transmission path of the primary topology optimization model meet the use requirements of the parts; if so, proceed to step 6; if not, adjust the optimization target and optimization constraint of the topology optimization, and perform secondary topology optimization to obtain the secondary optimization model; judging whether there are mutual force transmission paths and connections between the lifting ears in the secondary optimization model, if not, perform cyclic topology optimization on the secondary optimization model until there are mutual force transmission paths between the lifting ears, and proceed to step 6;

[0012] Step 6, performing three-dimensional reconstruction to obtain a three-dimensional reconstructed model;

[0013] Step 7: Perform mechanical and modal analysis on the three-dimensional reconstructed model to verify whether it meets the working requirements. If so, the topological optimization of the aircraft precooler connector structure is achieved.

[0014] Furthermore, the functional requirement is that the four lifting ears are connected to each other, and the applied loads are the forces and moments at the four lifting ears.

[0015] Furthermore, the pre-processing model is a finite element model of the original blank before the part is machined, specifically including four U-shaped thin plates connecting the lifting ears and the bottom.

[0016] Furthermore, the non-optimizable areas are the four connecting ears and the bottom U-shaped thin plate of the pre-processed model.

[0017] Furthermore, the grid division is performed using Cartesian grid.

[0018] Furthermore, the mesh size is 2 mm.

[0019] Furthermore, the material parameters of the optimized region include density, elastic modulus, Poisson's ratio and yield strength.

[0020] Furthermore, the specific process of step 4 is: taking the mass response as the optimization target, taking the stress response as the optimization constraint, setting the optimization target to minimize the mass, and setting the optimization constraint to stress not greater than 1000 MPa, performing a topology optimization on the optimizable area, and obtaining a topology optimization model.

[0021] Furthermore, in step 5, adjusting the optimization objective and optimization constraint of the topology optimization includes adjusting the optimization objective of the topology optimization to minimize flexibility, and adjusting the optimization constraint mass to 8% of the mass of the pre-processed model.

[0022] Furthermore, in step 7, if the working requirements are not met, the stress-bearing area that does not meet the structural requirements in the three-dimensional reconstructed model obtained in step 6 is adjusted to meet the working requirements.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] Based on the premise that the purchase-to-flight ratio and manufacturing cost of existing aircraft precooler connectors are too high, the present invention uses a topology optimization method and adopts at least two different topology optimization methods while meeting the performance requirements and assembly requirements of the connectors under normal working conditions. Finally, the optimization model is reconstructed to achieve a lightweight design of the aircraft precooler connector, shorten the design cycle, and reduce the manufacturing cycle and cost.

[0025] Furthermore, the optimization objective is first set to minimize mass, and the optimization constraint is stress, to obtain the first optimization model and mass percentage, and the second optimization objective is to minimize flexibility, and the optimization constraint is the mass percentage obtained by the first optimization. By constraining two different optimization objectives, it is conducive to obtaining better optimization results. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a flow chart of the optimization method of the present invention;

[0027] Figure 2 The figure is a three-dimensional model of the original blank of the aircraft precooler connector; wherein (a) is the front side of the model, and (b) is the back side of the model;

[0028] Figure 3 Finite element models for setting up optimizable and non-optimizable areas;

[0029] Figure 4 This is the model after a topology optimization.

[0030] Figure 5 It is a secondary topology optimization model;

[0031] Figure 6 It is a secondary reconstruction model;

[0032] Figure 7 This is the mechanical verification analysis of the reconstructed model. Among them, (a) is the equivalent stress cloud map, and (b) is the deformation cloud map;

[0033] Figure 8 Model optimized for laser powder bed additive manufacturing. DETAILED DESCRIPTION

[0034] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The following examples are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0035] like Figure 1 As shown, a method for optimizing the structure of an aircraft precooler connector based on topology optimization comprises the following steps:

[0036] Step 1, determine the functional requirements and external loads of the precooler connector. In this embodiment, the functional requirement is that the four hanging ears must be connected to each other, and the external loads are mainly the forces and moments at the four hanging ears. According to the above requirements, mechanical analysis and modal analysis are performed on the pre-processing model to obtain the stress and deformation areas of the pre-processing model; wherein, the mechanical analysis is mainly static analysis, and the modal analysis mainly determines the first 6 vibration frequencies of the pre-processing model. The above-mentioned mechanical analysis and modal analysis are performed using the relevant finite element analysis modules in ANSYS Workbench; wherein, the pre-processing model refers to the finite element model of the original blank before the part is machined, specifically including four connecting hanging ears and a U-shaped thin plate at the bottom, such as Figure 2 As shown,

[0037] Step 2, setting the deformation and stress area of ​​the pre-processed model obtained in the previous step as the non-optimized area. The non-optimized area in the present invention is mainly the four connecting ears and the U-shaped thin plate at the bottom of the pre-processed model, such as Figure 3 As shown in the figure, the rest of the pre-processed model is set as the optimizable area. The model after setting the non-optimizable area and the optimizable area is imported into the topology optimization software, such as Hyperworks.

[0038] Step 3, meshing the model after setting the non-optimizable area and the optimizable area. In the present invention, Cartesian mesh is mainly used, and the mesh size is adjusted according to the model size. In the present invention, the mesh size is 2mm, and material parameters are applied to the optimizable area, mainly density, elastic modulus, Poisson's ratio and yield strength;

[0039] Step 4: Perform a topological optimization on the optimizable area. First, take the mass response as the optimization target and the stress response as the optimization constraint. Set the optimization target to minimize the mass. The optimization constraint is that the stress is not greater than 1000MPa according to the design requirements. Figure 4 The primary topology optimization model shown in the figure has a primary topology optimization target mass of 8% of the total mass of the pre-processed model, which means that the structure can meet the strength requirements with 8% mass.

[0040] Step 5, make a preliminary judgment on the primary topology optimization model obtained in step 4, mainly to observe whether the force transmission path and connection of the primary topology optimization model meet the use requirements of the parts, that is, whether the four force-bearing lifting ears are connected to each other; if they do, the optimization is completed and three-dimensional reconstruction can be performed directly; if they do not meet the requirements, it means that a force path has been optimized, then it is necessary to adjust the optimization goal and optimization constraints of the topology optimization, and perform secondary topology optimization. The force path between the four lifting ears of the primary optimization model in this embodiment is optimized and does not meet the structural requirements. According to the mass percentage obtained by the primary topology optimization, the optimization goal is adjusted to minimize flexibility, and the optimization constraint mass is set to 8% of the mass of the pre-processed model, as shown below. Figure 5 The quadratic optimization model shown.

[0041] Step 6, judging the secondary optimization model obtained in step 5, mainly judging whether the main force transmission path and connection of the secondary optimization model exist. If not, it means that the mass percentage is too small, and the optimization constraint needs to be fine-tuned, mainly to increase the mass percentage and restore the force transmission path between the lifting ears that has been optimized and removed, that is, to perform cyclic topology optimization on the secondary optimization model in step 5 until the force transmission paths between the lifting ears are satisfied;

[0042] Step 7, the secondary optimization model that meets the design requirements is 3D reconstructed in 3D modeling software to obtain a 3D reconstructed model. For example, the 3D modeling software is UG, etc., mainly referring to the size of the optimization model, such as Figure 6 shown.

[0043] Step 8: Import the 3D reconstructed model into finite element analysis software for mechanical and modal analysis to verify whether it meets the work requirements, such as Figure 7 If it is satisfied, the topological optimization of the aircraft precooler connector structure is achieved. Otherwise, the three-dimensional reconstructed model obtained in step 7 needs to be adjusted, mainly adjusting the stress-bearing area that does not meet the structural requirements.

[0044] According to the topology optimization results, the obtained optimization model not only meets the mechanical performance requirements, but also greatly reduces the structural weight, providing a reference for the design and optimization of aerospace components.

[0045] In the present invention, the model after secondary optimization and reconstruction can meet the use requirements. Under the condition of ensuring strength, the final weight of the part is reduced by 46% compared with the original design. Finally, the optimized model is manufactured by laser powder bed additive manufacturing. Figure 8 shown.

[0046] In the present invention, first, according to the functional requirements and external loads of the precooler connector, the pre-processed model is subjected to mechanical analysis and modal analysis to obtain its stress and deformation areas; then, the deformation and stress areas are set as non-optimizable areas, and the remaining parts are optimized areas, and the optimized areas are topologically optimized; when performing topological optimization, at least two optimization designs with different objectives and constraints are performed. The first optimization goal is set to minimum mass, and the optimization constraint is stress; the second optimization goal is minimum flexibility, and the optimization constraint is the minimum mass percentage obtained after the first topological optimization. Finally, the obtained optimized model is three-dimensionally reconstructed, and mechanical analysis and modal analysis are performed to verify whether it meets the design requirements. If it meets the design requirements, the aircraft precooler connector after weight reduction is obtained. Otherwise, according to the results of the mechanical analysis, the optimization constraints (i.e., mass percentage) of the secondary topological optimization or the three-dimensional reconstruction design scheme are adjusted, and the design is redesigned to finally obtain a lightweight structural part that meets the use requirements.

Claims

1. A structural optimization method for aircraft precooler connectors based on topology optimization, characterized in that: The steps include: Step 1: According to the functional requirements and external loads of the precooler connector, mechanical analysis and modal analysis are performed on the preprocessing model to obtain the stress and deformation areas of the preprocessing model; Step 2, setting the deformation and stress areas of the pre-processed model as non-optimizable areas, and setting the rest of the pre-processed model as optimizable areas; Step 3, meshing the model after setting the non-optimizable area and the optimizable area; Step 4: Taking the mass response as the optimization target and the stress response as the optimization constraint, a topology optimization is performed on the optimizable area to obtain a topology optimization model; Step 5, judging whether the connection and force transmission path of the primary topology optimization model meet the use requirements of the parts; if so, proceed to step 6; if not, adjusting the optimization target and optimization constraint of the topology optimization, and performing secondary topology optimization to obtain the secondary optimization model; judging whether there are mutual force transmission paths and connections between the lifting ears in the secondary optimization model, if not, performing cyclic topology optimization on the secondary optimization model until there are mutual force transmission paths between the lifting ears, and proceeding to step 6; adjusting the optimization target and optimization constraint of the topology optimization includes adjusting the optimization target of the topology optimization to minimize flexibility, and adjusting the optimization constraint quality to 8% of the pre-processing model quality; Step 6, performing three-dimensional reconstruction to obtain a three-dimensional reconstructed model; Step 7: Perform mechanical and modal analysis on the three-dimensional reconstructed model to verify whether it meets the working requirements. If so, the topological optimization of the aircraft precooler connector structure is achieved.

2. The aircraft precooler connector structure optimization method based on topology optimization according to claim 1, characterized in that: The functional requirement is that the four lifting eyes are connected to each other, and the applied loads are the forces and moments at the four lifting eyes.

3. The method for optimizing the structure of an aircraft precooler connector based on topology optimization according to claim 1, characterized in that: The pre-processing model is the finite element model of the original blank before machining the part, specifically including four U-shaped thin plates connecting the lifting ears and the bottom.

4. The method for optimizing the structure of an aircraft precooler connector based on topology optimization according to claim 1, characterized in that: The non-optimizable areas are the four connecting ears and the bottom U-shaped thin plate of the pre-processed model.

5. The aircraft precooler connector structure optimization method based on topology optimization according to claim 1, characterized in that: The grid division is performed using Cartesian grid.

6. The aircraft precooler connector structure optimization method based on topology optimization according to claim 5, characterized in that: The grid size is 2 mm.

7. The method for optimizing the structure of an aircraft precooler connector based on topology optimization according to claim 1, characterized in that: The material parameters in the optimizable area include density, elastic modulus, Poisson's ratio, and yield strength.

8. The aircraft precooler connector structure optimization method based on topology optimization according to claim 1, characterized in that: The specific process of step 4 is: set the optimization goal to minimize the mass, set the optimization constraint to stress not greater than 1000MPa, perform a topology optimization on the optimizable area, and obtain a topology optimization model.

9. The method for optimizing the structure of an aircraft precooler connector based on topology optimization according to claim 1, characterized in that: In step 7, if the working requirements are not met, the stress-bearing area that does not meet the structural requirements in the three-dimensional reconstructed model obtained in step 6 is adjusted to meet the working requirements.

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