A forward design method for on-site conformal design of large-aperture structures based on simulation

Abstract

This invention belongs to the field of mold manufacturing technology and discloses a forward design method for on-site conformal molding scheme of large opening structures based on simulation. The steps are as follows: Step 1: Simplify the large opening structure and establish a high-fidelity finite element simulation model; simulate the deformation of the large opening structure under actual working conditions, evaluate the degree of elastic deformation of the large opening structure based on surface variance calculation, and select the support points of the conformal molding tooling according to the degree of elastic deformation; Step 2: Based on the support points of the conformal molding tooling, design and optimize the conformal molding tooling model considering the deformation factors of the large opening structure and the volume factors of the conformal molding tooling; Step 3: Install the conformal molding tooling model. In the high-fidelity finite element simulation model, a deformation simulation analysis of the large opening structure under conformal state is carried out, and the surface variance under conformal state is calculated; Step 4: Select the force control axis at the end of the support point of the conformal tooling, design simulation to obtain the contact force of the force control axis and the surface variance of the support point, and establish a mathematical model between the contact force of the force control axis and the surface variance of the support point; Step 5: During the conformal process on site, use a laser tracker to measure the position error of the support point of the conformal tooling, evaluate its surface variance, and calculate the contact force based on the mathematical model between the contact force of the force control axis and the surface variance of the support point.

Description

Technical Field

[0001] This invention belongs to the field of forward design technology for flexible conformal tooling, and specifically relates to a forward design method for on-site conformal schemes of large opening structures based on simulation. Background Technology

[0002] In the overall design and functional requirements of aircraft, a large number of hatch openings are generally required on the fuselage. This creates numerous open areas in the fuselage sections. These large-opening cabin structures, formed by the connection of opening frames and other areas with other components, cause drastic changes in the structural rigidity and force transmission of the fuselage. This makes the wing-fuselage joint area prone to twisting and deformation during assembly, and also causes significant displacement deviations at the wing-fuselage joint, affecting the assembly coordination of the wing-fuselage joint and leading to assembly difficulties. Forced assembly, on the other hand, generates significant assembly stress. Therefore, the assembly process of large components determines the final quality of the aircraft. During assembly, it is essential to ensure high-precision installation and assembly when continuously large-opening components are connected to other groups and components.

[0003] In the actual assembly process of product components, on the one hand, due to its own structure and assembly process, the large opening structure is a typical structure that is prone to instability and deformation under uneven stress, and the assembly deformation state is difficult to control; on the other hand, the large opening docking structure generally has the characteristics of large size, variable curvature, and variable thickness, which can lead to assembly errors such as positioning gaps and warping under positioning errors, manufacturing errors, and loads. This makes it difficult for the large opening cabin structure of the aircraft to meet the requirements of coaxiality, aerodynamic shape accuracy, and assembly coordination accuracy. Therefore, due to the combined effects of forming errors, tooling manufacturing errors, positioning errors, and assembly deformation of large-opening structures, the deformation of continuous large-opening structures during orientation adjustment, positioning, and transfer transportation is difficult to control. Existing assembly processes can only maintain the opening shape by installing two layers of traditional standard conforming frames or special assembly fixtures on the end face of the large-opening structure. Moreover, the design of conforming fixtures often relies on design experience and lacks theoretical analysis of the structural form, strength, and support point selection of conforming fixtures. This results in poor conforming fixture correction effect, making it difficult to solve the problems of excessive local deformation and assembly incoordination of large-opening structures, while also failing to meet the design requirements for lightweight conforming fixtures.

[0004] Therefore, there is an urgent need for a forward design method for flexible conforming tooling for large opening structures, which can meet the requirements of deformation control, lightweight design of conforming tooling, and automatic adjustment of flexible tooling during the assembly process of large opening structures, and support the digitalization and automation of the assembly process of large opening structures. Summary of the Invention

[0005] Purpose of the invention: To address the aforementioned problems, this invention proposes a forward design method for on-site conformal design of large-opening structures based on simulation. First, the local deformation of the large-opening structure is analyzed using finite element simulation. A topology optimization design method for large-opening structures considering local conformal constraints is proposed to achieve lightweight design of flexible tooling. Then, partial least squares regression is used to establish a mathematical model with the deformation of the tooling conformal points as independent variables and the tooling force adjustment control axis as dependent variables. Finally, based on the deformation results of the conformal tooling support points measured on-site, the contact force required for the conformal adjustment of each force control axis is determined. Summary of the Invention:

[0007] A simulation-based forward design method for on-site conformal design of large-aperture structures, comprising the following steps:

[0008] Step 1: Simplify the large opening structure and establish a high-fidelity finite element simulation model; simulate the deformation of the large opening structure under actual working conditions, calculate and evaluate the degree of elastic deformation of the large opening structure based on the surface variance, and select the support points of the conformal tooling according to the degree of elastic deformation.

[0009] Step 2: Based on the support points of the conformal tooling, design and optimize the conformal tooling model, taking into account the deformation factors of the large opening structure and the volume factors of the conformal tooling.

[0010] Step 3: Install the conformal tooling model into the high-fidelity finite element simulation model, conduct deformation simulation analysis of the large opening structure under conformal conditions, and calculate the surface variance under conformal conditions;

[0011] Step 4: Select the end of the shape-preserving structure positioning support as the force control axis, design simulation to obtain data on the contact force of the force control axis and the deformation of the shape-preserving point under working conditions such as hoisting and transportation, and establish a mathematical model between the two;

[0012] Step 5: During the on-site shaping process, the positional error of the shaping tooling positioning support end is measured using a laser tracker, and its deformation degree is evaluated. The adjustment force of the corresponding adjustable positioning support end is calculated using the mathematical model established in the previous section, so as to realize the deformation control of the large opening structure.

[0013] Furthermore, in step one, the specific process is as follows:

[0014] 1.1 Based on the actual three-dimensional model of the large opening cabin, the large opening structure is extracted, and components that do not affect the structural simulation analysis results are removed from the large opening cabin model. Minor features are simplified to complete the establishment of a high-fidelity finite element simulation model of the large opening structure.

[0015] 1.2. Based on the actual working conditions of the large opening structure, different analysis steps are set to simulate the assembly process of the large opening structure. The mesh is divided, loads and boundary conditions are set in sequence. After the model conditions are set, the finite element simulation analysis calculation of the large opening structure is carried out.

[0016] 1.3 After the simulation analysis is completed, the deformation and stress distribution data of the opening frame are extracted, and the variance R of its surface shape at the contact end with the conformal tooling is calculated. 2 The expression is as follows;

[0017]

[0018] Where {Δu i}={u′ i}-{u i},{u′ i} represents the displacement of node i, and {u i} represents the rigid body displacement of node i, and N is the number of control nodes corresponding to the local region; in the calculation, the actual displacement of node i is {u′}. i The rigid body displacement {u} is obtained through finite element analysis. i It is obtained by solving for its translation and rotation.

[0019] 1.4. Select the right horizontal direction as 0° and divide the opening frame into regions along the directions of 45°, 135°, 225° and 315°. Calculate the surface variance of each local region to quantitatively characterize its elastic deformation under actual working conditions. Compare the deformation results of the local regions at equal intervals in the four directions and select the local region with the largest surface variance as the positioning support position of the conformal tooling.

[0020] Furthermore, in step two, the specific process is as follows:

[0021] 2.1 Establish an optimizable finite element analysis model of the conformal tooling, analyze the design domain and non-design domain of the structure, take the positioning support end of the conformal tooling on the large opening cabin structure as the non-design domain, and the main structure as the design domain, and define the boundary conditions and external loads.

[0022] 2.2 Using the strain energy of the structure as the optimization objective, and considering the requirements of deformation and mass, the surface variance and volume constraint upper limit of the shape preservation region are applied, and the structural topology optimization is performed using the solid isotropic material penalty method;

[0023] 2.3 After optimization, the tooling optimization model is exported. First, the topology optimization results are sliced ​​to obtain the cross-sectional curves. Straight lines are used for fitting. Then, considering the manufacturability of the structure, a hollow truss structure is selected to fit the fitted tooling shape to obtain the preliminary reconstruction results.

[0024] 2.4 After reconstruction, the model is imported, meshed, materials are defined, sections are specified, boundary conditions and loads are set in sequence. Abaqus software is used to perform static analysis on the reconstructed model to verify the static strength of the conformal tooling.

[0025] Furthermore, in step four, the specific process is as follows:

[0026] 4.1 The reconstructed conformal tooling positioning support end is designed as an adjustable mechanism, and a force control shaft is selected at the end of the support point;

[0027] 4.2 Design orthogonal simulation to simulate the deformation of the opening frame in the large opening cabin structure under different loads, obtain the contact force between the positioning support end face and the opening frame and the deformation of the positioning support end face, and calculate the surface variance of the positioning support end face of the conformal tooling.

[0028] 4.3 Based on the obtained data, a mathematical model was established using the least squares regression method, with the variance of the surface shape of the positioning support end face as the independent variable and the contact force between the positioning support structure and the opening frame as the dependent variable.

[0029] Furthermore, in step five, the process is as follows:

[0030] 5.1. The instrument is used to perform a full-range scan of the large opening structure and conformal tooling to be measured, and multiple scanning modes are switched to achieve scanning of different areas to obtain three-dimensional point cloud data of the structure. The scanning point cloud data is then reconstructed in three dimensions using the adaptation software to obtain the scanned three-dimensional model of the large opening structure and conformal tooling.

[0031] 5.2 Import the three-dimensional digital model of the structure into the measurement software, match the coordinate system between the three-dimensional digital model and the three-dimensional model obtained after loading and scanning, analyze the deviation between the two, use this as the position error of the positioning support end of the conformal tooling, and then calculate the surface variance of the area.

[0032] 5.3 Based on the mathematical model of the surface variance of the positioning support end of the conformal tooling and the contact force between it and the conformal structure, the surface variance obtained by scanning calculation is used as input to calculate the force required for the shape correction of the adjustable end of the conformal tooling. The adjustable end is adjusted manually or automatically to ensure that the contact force between the positioning support end face of the conformal tooling and the conformal surface of the large opening cabin structure meets the requirements.

[0033] 5.4 After the conformal tooling adjustment is completed, repeat steps 5.1-5.3 and make multiple feedback adjustments until the deformation of the conformal surface of the large opening cabin structure is reduced by 30% compared with before adjustment.

[0034] Furthermore, the mathematical model for the penalty method for solid isotropic materials is as follows:

[0035] Find:ρ i =i=1…N

[0036]

[0037] K(ρ i U = F

[0038]

[0039] 0.0001≤ρ i ≤1, i=1…n

[0040] Where i is the element number, ρ is the design variable, K, U, and F are the overall stiffness matrix, displacement vector, and external force vector, respectively, u and k are the stiffness matrix and displacement vector of a single element, C represents the total strain energy of the structure, and v i Represents the volume of the corresponding unit, V0 is the design volume of the total volume, and R 2 Represents the variance of the surface shape in a local area. This represents the variance of the local area surface shape before optimization.

[0041] Furthermore, in section 1.1, the components that are not affected include: bolts and skin.

[0042] Furthermore, in 1.1, minute features include: chamfers and holes.

[0043] The beneficial effects of this application are as follows:

[0044] This invention proposes a simulation-based forward design method for on-site conformal design of large-aperture structures, enabling deformation control of these structures. It achieves lightweight design of conformal tooling, establishes a force-displacement equilibrium control mathematical model, enhances the adjustability of assembly tooling, and significantly improves aircraft assembly quality and efficiency. Attached Figure Description

[0045] Figure 1 Flowchart of a forward design method for on-site conformal design of large opening structures based on simulation;

[0046] Figure 2 This is a schematic diagram of a typical structural simulation model with a large opening frame;

[0047] Figure 3 A simplified diagram illustrating the selection of shape-preserving points for a large-opening frame;

[0048] Figure 4 Flowchart for lightweight design of conformal tooling considering local displacement constraints;

[0049] Figure 5 A schematic diagram of the redesigned tooling to maintain its shape;

[0050] Figure 6 The relationship curve between the deformation of the shape-preserving tooling and the contact force is shown in the mathematical model. Detailed Implementation

[0051] The technical solutions of the embodiments of the present invention will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0052] The terms "first," "second," etc., used in the specification and claims of this invention are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0053] The human image analysis method provided by the present invention will be described in detail below with reference to the accompanying drawings, through specific embodiments and application scenarios.

[0054] To achieve precise control of deformation of large-opening structures during actual assembly using conformal tooling, this invention proposes a simulation-based forward design method for on-site conformal design of large-opening structures, such as... Figure 1 As shown, the steps are as follows:

[0055] 1. By reasonably simplifying the large opening structure, a high-fidelity finite element simulation model is established to simulate the deformation of the large opening structure under actual working conditions. The elastic deformation degree of the opening frame is evaluated based on the surface variance calculation, and the larger deformation area is selected as the support point of the conformal tooling.

[0056] 1.1 Based on the actual three-dimensional model of the large opening cabin, the large opening structure is extracted. In the large opening cabin model, components such as bolts, fasteners, and connecting plates that have little impact on the simulation analysis results are removed. Minor features such as chamfers and holes are simplified. On the basis of balancing computational efficiency and accuracy, a high-fidelity finite element simulation model of the large opening structure is established.

[0057] 1.2 Based on the actual working conditions of the large opening structure, different analysis steps are set to simulate the assembly process of the large opening structure. The mesh is divided, loads and boundary conditions are set in sequence, and after the model conditions are set, the finite element simulation analysis calculation of the large opening structure is performed.

[0058] 1.3 After the simulation analysis is completed, the deformation and stress distribution data of the open frame are extracted, and the surface variance of its contact surface with the conformal tooling is calculated. This variance is used as the local deformation field of the open frame when it is assembled under actual working conditions.

[0059] Surface variance can describe the degree of elastic deformation in a local area, and its expression is as follows:

[0060]

[0061] Where {Δu i}={u i ′}-{u i}, {u i ′} represents the displacement of node i, {u i Let {u'} represent the rigid body displacement of node i, and N be the number of control nodes corresponding to the local region. In the calculation, the actual displacement of node i is {u'}. i The rigid body displacement {u} is obtained through finite element analysis. i The result is obtained by solving for its translation and rotation.

[0062] According to the theory of elasticity, the rigid body displacement of an object can be expressed as:

[0063] u x =u 0x +ω y ×z-ω z ×y

[0064] u y =u 0y +ω z ×x-ω x ×z

[0065] u z =u 0z +ω x ×y-ω y ×x

[0066] The matrix form is represented as:

[0067]

[0068] Where ω x ,ω y ,ω z Represents the rotation of a rigid body about its axes, u x u y u z u represents the displacement along the x, y, and z directions. 0x ,u 0y ,u 0z Rigid body translation along the x, y, z directions.

[0069] make Then the above formula can be written as {u}={u0}+{T}{ω}.

[0070] {Δu} can be obtained through calculation. i}={u′ i}-{u0}-{T i}{ω}, thus the actual displacement of the node, the rigid body translation of the local region, the rigid body rotation, and the variance of the surface shape expressed by the coordinates of the node can be calculated.

[0071] 1.4 Select the right side of the horizontal direction as 0°, and divide the area along the opening frame counterclockwise at 45°, 135°, 225° and 315°. Calculate the surface variance of each local area to quantitatively characterize its elastic deformation under actual working conditions. Compare the deformation results of the local areas at equal intervals in the four directions, and select the local area with the largest surface variance as the positioning support position of the conformal tooling.

[0072] 2. Taking into account the deformation factors of the shape-preserving region of the open frame and the volume factors of the shape-preserving fixture, a topology optimization design for the shape-preserving fixture is carried out with the displacement and volume of the shape-preserving region as constraints.

[0073] 2.1 Establish an optimizable finite element analysis model of the conformal tooling, analyze the design domain and non-design domain of the structure, take the positioning support end of the conformal tooling on the large opening cabin structure as the non-design domain, and the main structure as the design domain, and define the boundary conditions and external loads.

[0074] 2.2 Taking the strain energy of the structure as the optimization objective, and considering the requirements of deformation and mass, the surface variance and volume constraint upper limit of the conformal region are applied to perform structural topology optimization. This allows the optimized conformal tooling to seek the optimal material distribution under the condition that the material usage and warping deformation of the conformal region are controlled within a certain range, thereby minimizing the structural compliance under given boundary conditions and external forces.

[0075] The optimization mathematical model for the Solid Isotropic Material Penalty (SIMP) method used is as follows:

[0076] Find:ρ i =i=1…N

[0077]

[0078] K(ρ i U = F

[0079]

[0080] 0.0001≤ρ i ≤1, i=1…n

[0081] Where i is the element number, ρ is the design variable, K, U, and F are the overall stiffness matrix, displacement vector, and external force vector, respectively, u and k are the stiffness matrix and displacement vector of a single element, C represents the total strain energy of the structure, and v i Represents the volume of the corresponding unit, V0 is the design volume of the total volume, and R 2 Represents the variance of the surface shape in a local area. This represents the variance of the local area surface shape before optimization.

[0082] 2.3 After optimization, the tooling optimization model is exported. First, the topology optimization results are sliced ​​to obtain the cross-sectional curves. Straight lines are used for fitting. Then, considering the manufacturability of the structure, a hollow truss structure is selected to fit the fitted tooling shape to obtain the preliminary reconstruction results.

[0083] 2.4 After reconstruction, the following operations are performed in sequence: importing the model, meshing, defining materials, sections, specifying sections, setting boundary conditions and loads, etc. The static analysis of the reconstructed model is performed using Abaqus software to verify the static strength of the conformal tooling.

[0084] 2.5 The optimized conformal tooling was installed into the large opening structure, and deformation simulation analysis of the large opening structure under conformal conditions was carried out. The surface variance of the opening frame in the large opening structure with and without the conformal tooling was compared to verify the degree of suppression of warping deformation of the easily deformable opening frame in the large opening cabin structure by the conformal tooling.

[0085] Third, after the shape-preserving tooling structure has been redesigned, in order to address the problem that the relationship between the adjustment force of the adjustable tooling and the deformation of the shape-preserving structure is unclear, the end of the positioning support of the shape-preserving structure is selected as the force control axis. Simulation is designed to obtain data on the contact force of the force control axis and the deformation of the shape-preserving point under lifting, transportation and other working conditions, and a mathematical model between the two is established.

[0086] 3.1 Based on the reconstructed conformal tooling, the positioning support end of the conformal tooling is designed as an adjustable mechanism, and a force control shaft is selected at the end of the positioning support point.

[0087] 3.2 Based on the above-designed tooling, in order to realize the automatic adjustment of the positioning support end face of the conformal tooling according to the force control axis, an orthogonal simulation was designed to simulate the deformation of the opening frame in the large opening cabin structure under different loads, obtain the contact force between the positioning support end face and the opening frame and the deformation of the positioning support end face, and calculate the surface variance of the positioning support end face of the conformal tooling.

[0088] 3.3 Based on the obtained data, a mathematical model was established using the least squares regression method, with the variance of the surface shape of the positioning support end face as the independent variable and the contact force between the positioning support structure and the opening frame as the dependent variable.

[0089] Fourth, during the on-site shaping process, the positional error of the shaping tooling positioning support end is measured using a laser tracker, and its deformation degree is evaluated. The adjustment force of the corresponding adjustable positioning support end is calculated using the mathematical model established in the previous section, so as to realize the deformation control of the large opening structure.

[0090] 4.1 The handheld instrument is used to perform a full-range scan of the large opening structure and conformal tooling to be tested, and multiple scanning modes are switched to achieve scanning of different areas to obtain three-dimensional point cloud data of the structure. The scanned point cloud data is then reconstructed in three dimensions using the adapter software to obtain the scanned three-dimensional model of the large opening cabin structure and conformal tooling.

[0091] 4.2 Import the three-dimensional digital model of the structure into the measurement software, match the coordinate system between the three-dimensional digital model and the three-dimensional model obtained after loading and scanning, analyze the deviation between the two, and use this as the position error of the positioning support end of the conformal tooling, so as to calculate the surface variance of the area.

[0092] 4.3 Based on the mathematical model established in the previous section regarding the surface variance of the positioning support end of the conforming tool and the contact force between it and the conforming structure, the surface variance obtained from the scanning calculation is used as input to calculate the force required for the shape correction of the adjustable end of the conforming tool. By manually or automatically adjusting the adjustable end, the contact force between the positioning support end face of the conforming tool and the conforming surface of the large opening cabin structure meets the requirements.

[0093] 4.4 After the conformal tooling is adjusted, the laser tracker is used again to measure the large opening cabin structure and the conformal tooling, analyze the deformation state, and make multiple feedback adjustments until the deformation of the conformal surface of the large opening cabin structure is reduced by 30% compared with before adjustment, thus completing the positive design of the adjustable tooling.

[0094] Example

[0095] 1. The asymmetric large opening structure is reasonably simplified and a high-fidelity finite element simulation model is established to simulate the deformation of the large opening structure under actual working conditions. The deformation results are extracted, and the elastic deformation degree of the opening frame is evaluated based on the surface variance calculation. The larger deformation area is selected as the positioning support point of the conformal tooling.

[0096] 1.1 Based on the actual large-opening structure produced, a typical asymmetrical large-opening structure with a length of 6000mm, a width of 2000mm, and a height of 3000mm was designed. The left frame opening diameter is 1400mm, and the right frame opening diameter is 1600mm. Figure 2 As shown. The structure was modeled using CATIA software to obtain its digital model.

[0097] 1.2 According to the requirements of mesh generation, the large opening model is appropriately simplified, non-key components such as bolts and skin are removed, and the main load-bearing components are retained. The simplified structure is imported into ABAQUS software and assembled to obtain the finite element model of the large opening structure. The material selected is 6061T6 aluminum alloy, and the material parameters are shown in Table 1.

[0098] Table 1. Material parameters of 6061T6 aluminum alloy

[0099]

[0100] Note: E is the elastic modulus, v is Poisson's ratio, σ s X is the yield strength. t This refers to tensile strength.

[0101] 1.3 The large opening structure adopts tetrahedral unit C3D6. In the contact module, different components are bound and constrained to simulate the fixed relationship between the components.

[0102] 1.4 In the load and boundary module, the five degrees of freedom of the lifting point of the large opening structure, except for the movement in the z direction, are restricted according to the actual working conditions. A motion coupling reference point is established in the lifting point area. A tensile displacement of 100mm is applied in the z direction, and the gravity field of the whole structure is applied in the LOAD module.

[0103] 1.5 Finite element simulation was performed. The three-dimensional finite element simulation results of the large opening structure were read. The large opening frame was selected as a square region with a length and width of 100mm. The displacement U of all nodes in this region was extracted. The surface variance of different regions was calculated according to the concept of surface variance. Several symmetrical regions with large surface variances were selected as shape-preserving points. Finally, the shape-preserving points of the large opening frame were selected as follows: Figure 3 As shown in Table 2, the variance of the surface shape in this region is as follows.

[0104] Table 2. Variance of surface shape in the conformal region

[0105]

[0106]

[0107] II. Taking into account the variance of the shape-preserving region of the open frame calculated in the previous section and the volume factor of the shape-preserving fixture, a topology optimization design for the shape-preserving fixture is carried out with the variance of the shape-preserving region and the volume as constraints. The design process is as follows: Figure 4 As shown.

[0108] 2.1 Based on the shape-preserving points determined in the previous section, an optimization model considering local displacement constraints is designed. The structural design domain is a cuboid of 3800×1300×1200mm, and the non-design domain is the corresponding shape-preserving positioning support structure.

[0109] 2.2 Using Python, we wrote a program with the minimum strain energy of the structure as the optimization objective and constraints on the surface variance and volume of the conformal region within a certain range. The upper limit of the surface variance of conformal points 1-8 is 50% and the volume is 10%. We performed topology optimization on the structure and imported the optimization results into Abaqus software for dynamic and static simulation. We extracted the surface variance and volume results and determined the final optimized structure through iteration.

[0110] 2.2 Taking the strain energy of the structure as the optimization objective, and considering the requirements of deformation and mass, the surface variance and volume constraint upper limit of the conformal region are applied to perform structural topology optimization. This allows the optimized conformal tooling to seek the optimal material distribution under the condition that the material usage and warping deformation of the conformal region are controlled within a certain range, thereby minimizing the structural compliance under given boundary conditions and external forces.

[0111] 2.3 After optimization, the tooling optimization model is exported. Based on the results and empirical methods, the model is reconstructed. First, the topology optimization results are sliced ​​to obtain cross-sectional curves, which are then fitted using straight lines. Then, considering the manufacturability of the structure, some components are appropriately modified to obtain preliminary reconstruction results, such as... Figure 6 As shown.

[0112] 2.4 The above-mentioned reconstructed model was imported into Abaqus software. The structure uses tetrahedral C3D6 elements and 6061T6 aluminum alloy as the material. The material parameters are shown in Table 1. Then, in the load and boundary condition module, the support points were fixed and gravity was applied to carry out static analysis of the structure. No large stress concentrations were found in the structure, so the static strength can be considered to meet the requirements.

[0113] 2.5 The above conformal tooling model was assembled into the large opening structure model in Abaqus software, and the deformation simulation analysis of the large opening structure under conformal state was carried out. The surface variance of the conformal region under conformal state is shown in Table 3. The conformal tooling has a significant suppressive effect on the warping deformation of the conformal region.

[0114] Table 3. Variance of surface shape of the conforming region under conforming conditions.

[0115]

[0116] Third, after the structural reconstruction design of the conformal tooling is completed, in order to address the problem of flexible tooling, a force control axis is selected at the end of the support point, and simulation is designed to obtain data on the contact force of the force control axis and the deformation of the conformal positioning support end under working conditions such as hoisting and transportation, and a mathematical model between the two is established.

[0117] 3.1 Based on the reconstructed shape-keeping tooling, the shape-keeping positioning support end is designed as an adjustable mechanism in actual manufacturing, and a force control shaft is selected at the end of the positioning support.

[0118] 3.2 Orthogonal simulation was designed. In the load module, equidistant vertical loads of 0-100N were applied along the left and right open frames at 45°, 135°, 225° and 315° respectively. Deformation simulation of the open frames under different loads was carried out. The contact force between the support structure and the conformal frame structure and the deformation of the support points were extracted from the results. The sum of the surface variances of the eight support points was calculated, as shown in Table 4 below.

[0119] Table 4. Contact force increment and deformation at support points under different loads.

[0120]

[0121] 3.3 Based on the data in the table above, a mathematical model was established using the least squares regression method, with the variance of the surface shape of the positioning support end face as the independent variable and the contact force between the positioning support structure and the structure being preserved as the dependent variable. The mathematical model curve is shown in Figure 3.3. Figure 6 As shown.

[0122] Fourth, the position error of the positioning support end face of the conformal tooling is measured by a laser tracker, and its surface variance is evaluated. The adjustment force of the corresponding adjustable clamping end is calculated based on the mathematical model established in the previous section, so as to realize the deformation control of the large opening structure.

[0123] 4.1 The handheld instrument is used to perform a full-range scan of the manufactured large-opening structure and conformal tooling to obtain the three-dimensional point cloud data of the structure. The scanned point cloud data is then reconstructed in three dimensions using software adapted to the laser scanner to obtain the scanned three-dimensional model of the large-opening structure and conformal tooling.

[0124] 4.2 Import the three-dimensional digital model of the structure into the measurement software, match the coordinate system between the three-dimensional digital model and the three-dimensional model obtained by scanning, analyze the deviation between the two, and use this as the position error of the positioning support end face of the conformal tooling. The variance of the surface shape in this area is calculated as shown in Table 5.

[0125] 4.3 The above mathematical model was imported into the control system of the on-site tooling. The surface variance was input in the control panel, and the adjustable end was automatically adjusted to achieve automatic adjustment control of deformation. Finally, the surface variance of the area is shown in Table 5. The deformation of the shape-preserving area was reduced by 41%, which meets the design requirements.

[0126] Table 5. Variance of surface shape in the shape-preserving area before and after automatic adjustment.

[0127]

[0128] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of the present invention is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0129] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art, under the guidance of the present invention, can make many other forms without departing from the spirit and scope of protection of the claims, and all such forms are within the protection scope of the present invention.

Claims

1. A forward design method for on-site conformal design of large-aperture structures based on simulation, characterized by the following steps: Step 1: Simplify the large opening structure and establish a high-fidelity finite element simulation model; simulate the deformation of the large opening structure under actual working conditions, evaluate the degree of elastic deformation of the large opening structure based on the surface variance calculation, and select the support points of the conformal tooling according to the degree of elastic deformation; the specific process is as follows: 1.1 Based on the actual three-dimensional model of the large opening cabin, the large opening structure is extracted, and components that do not affect the structural simulation analysis results are removed from the large opening cabin model. Minor features are simplified to complete the establishment of a high-fidelity finite element simulation model of the large opening structure. 1.

2. Based on the actual working conditions of the large opening structure, different analysis steps are set to simulate the assembly process of the large opening structure. The mesh is divided, loads and boundary conditions are set in sequence. After the model conditions are set, the finite element simulation analysis calculation of the large opening structure is carried out. 1.3 After the simulation analysis is completed, the deformation and stress distribution data of the opening frame are extracted, and the variance of its surface shape at the contact end with the conformal tooling is calculated. R 2 The expression is as follows; in , Let be the displacement of node i. Let represent the rigid body displacement of node i, and N be the number of control nodes corresponding to the local region; in the calculation, the actual displacement of node i... Rigid body displacement obtained through finite element analysis It is obtained by solving for its translation and rotation. 1.

4. Select the right horizontal direction as 0° and divide the opening frame into regions along the directions of 45°, 135°, 225° and 315°. Calculate the surface variance of each local region to quantitatively characterize its elastic deformation under actual working conditions. Compare the deformation results of the local regions at equal intervals in the four directions and select the local region with the largest surface variance as the positioning support position of the conformal tooling. Step 2: Based on the support points of the conformal tooling, design and optimize the conformal tooling model, taking into account the deformation factors of the large opening structure and the volume factors of the conformal tooling. Step 3: Install the conformal tooling model into the high-fidelity finite element simulation model, conduct deformation simulation analysis of the large opening structure under conformal conditions, and calculate the surface variance under conformal conditions; Step 4: Select the end of the shape-preserving structure positioning support as the force control axis, design simulation to obtain data on the contact force of the force control axis and the deformation of the shape-preserving point under working conditions such as hoisting and transportation, and establish a mathematical model between the two; Step 5: During the on-site shaping process, the positional error of the shaping tooling positioning support end is measured using a laser tracker, and its deformation degree is evaluated. The adjustment force of the corresponding adjustable positioning support end is calculated using the mathematical model established in the previous section, so as to realize the deformation control of the large opening structure.

2. The method according to claim 1, characterized in that: Step two involves the following steps: 2.1 Establish an optimizable finite element analysis model of the conformal tooling, analyze the design domain and non-design domain of the structure, take the positioning support end of the conformal tooling on the large opening cabin structure as the non-design domain, and the main structure as the design domain, and define the boundary conditions and external loads. 2.2 Using the strain energy of the structure as the optimization objective, and considering the requirements of deformation and mass, the surface variance and volume constraint upper limit of the shape preservation region are applied, and the structural topology optimization is performed using the solid isotropic material penalty method; 2.3 After optimization, the tooling optimization model is exported. First, the topology optimization results are sliced ​​to obtain the cross-sectional curves. Straight lines are used for fitting. Then, considering the manufacturability of the structure, a hollow truss structure is selected to fit the fitted tooling shape to obtain the preliminary reconstruction results. 2.4 After reconstruction, the model is imported, meshed, materials are defined, sections are specified, boundary conditions and loads are set in sequence. Abaqus software is used to perform static analysis on the reconstructed model to verify the static strength of the conformal tooling.

3. The method according to claim 2, characterized in that: Step four involves the following specific steps: 4.1 The reconstructed conformal tooling positioning support end is designed as an adjustable mechanism, and a force control shaft is selected at the end of the support point; 4.2 Design orthogonal simulation to simulate the deformation of the opening frame in the large opening cabin structure under different loads, obtain the contact force between the positioning support end face and the opening frame and the deformation of the positioning support end face, and calculate the surface variance of the positioning support end face of the conformal tooling. 4.3 Based on the obtained data, a mathematical model was established using the least squares regression method, with the variance of the surface shape of the positioning support end face as the independent variable and the contact force between the positioning support structure and the opening frame as the dependent variable.

4. The method according to claim 3, characterized in that: Step five involves the following process: 5.

1. The instrument is used to perform a full-range scan of the large opening structure and conformal tooling to be measured, and multiple scanning modes are switched to achieve scanning of different areas to obtain three-dimensional point cloud data of the structure. The scanning point cloud data is then reconstructed in three dimensions using the adaptation software to obtain the scanned three-dimensional model of the large opening structure and conformal tooling. 5.2 Import the three-dimensional digital model of the structure into the measurement software, match the coordinate system between the three-dimensional digital model and the three-dimensional model obtained after loading and scanning, analyze the deviation between the two, use this as the position error of the positioning support end of the conformal tooling, and then calculate the surface variance of the area. 5.3 Based on the mathematical model of the surface variance of the positioning support end of the conformal tooling and the contact force between it and the conformal structure, the surface variance obtained by scanning calculation is used as input to calculate the force required for the shape correction of the adjustable end of the conformal tooling. The adjustable end is adjusted manually or automatically to ensure that the contact force between the positioning support end face of the conformal tooling and the conformal surface of the large opening cabin structure meets the requirements. 5.4 After the conformal tooling adjustment is completed, repeat steps 5.1-5.3 and make multiple feedback adjustments until the deformation of the conformal surface of the large opening cabin structure is reduced by 30% compared with before adjustment.

5. The method according to claim 4, characterized in that: In section 1.1, the components that are not affected include: bolts and skin.

6. The method according to claim 5, characterized in that: In 1.1, minute features include: chamfers and holes.

Images