Optimization method for supporting position of bottom bracket of fuselage cylinder section

Abstract

The invention provides an optimization method for the supporting position of a bottom bracket of a fuselage cylinder section, and the method comprises the steps: building a three-dimensional simplified model of the fuselage cylinder section, and setting material performance parameters; establishing a fuselage cylinder section bottom bracket three-dimensional simplified model, and setting mechanical boundary conditions and material performance parameters; grid division is carried out on the fuselage cylinder section three-dimensional simplified model and the fuselage cylinder section bottom bracket three-dimensional simplified model; setting an initial position of the fuselage barrel section bottom bracket three-dimensional simplified model, completing model assembly together with the fuselage barrel section three-dimensional simplified model, and setting a constraint relation; solving a stress result and a deformation result of the bottom of the fuselage cylinder section under the condition of the supporting position of the bracket; and changing the position of the fuselage cylinder section bottom bracket three-dimensional simplified model. According to the method, the support position of the bottom bracket of the fuselage barrel section can be optimized by considering the influence of the weight of the fuselage barrel section, the length of the fuselage barrel section, the support position of the bracket and the support number of the bracket.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft component assembly, and in particular relates to a method for optimizing the support position of a bottom bracket of a fuselage barrel section. Background Art

[0002] The fuselage barrel section of modern aircraft is mainly a large thin-walled cylindrical structure, which requires shape and position control through a bottom bracket support system during the assembly process. If the bottom bracket support position is unreasonable, it will cause the fuselage barrel section to undergo large or local deformation during the assembly process, resulting in a decline in assembly quality. During the assembly process, due to the use of high-speed automated assembly equipment on site, the operation of the equipment will cause additional deformation to the fuselage barrel section, and more stringent requirements are placed on the bottom bracket support stiffness. In addition, as aircraft develop towards larger sizes and a higher proportion of composite materials, it is also necessary to reasonably arrange the bottom bracket support position of the fuselage barrel section.

[0003] The calculation method for the fuselage barrel bottom bracket support position is mainly to treat the fuselage barrel as the center of mass and solve the force and moment balance equation. However, this calculation simplifies the fuselage barrel into a rigid body and fails to consider the deformation of the fuselage barrel itself, the interaction between the fuselage barrel and the bracket, and the local assembly deformation. This is significantly different from the actual situation and cannot accurately reflect the rationality of the bottom bracket support position, resulting in fuselage barrel deformation caused by the unreasonable bottom bracket support position. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem that the traditional calculation model cannot take into account the deformation of the fuselage barrel section itself, the interaction force between the fuselage barrel section and the bracket, and the local assembly deformation, which is very different from the actual situation, resulting in the inability to accurately reflect the rationality of the bottom bracket support position, resulting in the deformation of the fuselage barrel section caused by the unreasonable bottom bracket support position.

[0005] The present application provides a method for optimizing the support position of a bottom bracket of a fuselage barrel section, comprising: Step 1: Create a simplified 3D model of the fuselage barrel section and set the material performance parameters; Step 2: Establish a simplified three-dimensional model of the fuselage barrel bottom bracket and set the mechanical boundary conditions and material performance parameters; Step 3: Mesh the simplified 3D model of the fuselage barrel section and the simplified 3D model of the fuselage barrel section bottom bracket; Step 4: Set the initial position of the simplified 3D model of the fuselage barrel bottom bracket, complete the model assembly together with the simplified 3D model of the fuselage barrel, and set the constraint relationship; Step 5: Calculate the stress and deformation results of the bottom of the fuselage barrel section when the bracket is in the supported position. Step 6: Change the position of the simplified 3D model of the bracket at the bottom of the fuselage barrel section and repeat step 5 to complete the stress and deformation calculation results under different bracket support positions. Select the optimal bracket support position based on the results.

[0006] Preferably, the step 1 includes: Step 1-1: Use CAE software to create a simplified 3D model of the fuselage barrel section, retaining at least the skin, fuselage frame, and bottom plate beams; Step 1-2: Set the Young's modulus, Poisson's ratio, and material density of the three-dimensional simplified structure of the fuselage barrel section according to the actual material type used; Preferably, the three-dimensional simplified model of the fuselage barrel section in step 1-1 has the following requirements: The weight, length, width and height of the simplified three-dimensional model of the fuselage barrel section are consistent with the actual dimensions.

[0007] Preferably, the second step includes: Step 2-1: Create a simplified 3D model of the fuselage barrel bottom bracket using CAE software; Step 2-2: Set a 6-DOF constraint as a mechanical boundary condition on the lower surface of the simplified 3D model of the fuselage barrel bottom bracket. Step 2-3: According to the actual material type, set the Young's modulus, Poisson's ratio, and material density to establish the simplified three-dimensional model of the fuselage barrel bottom bracket.

[0008] Preferably, the three-dimensional simplified model of the fuselage barrel bottom bracket in step 2-1 has the following requirements: The contact area between the simplified 3D model of the fuselage barrel bottom bracket and the simplified 3D model of the fuselage barrel must be consistent with the actual object. Preferably, the step three has the following requirements: Divide the three-dimensional simplified model of the fuselage barrel bottom bracket and the three-dimensional simplified model of the fuselage barrel section into grid units. This requires checking the sizes of all grid units. The minimum value of the three-dimensional simplified model of the fuselage barrel bottom bracket must not be less than the maximum value of the grid unit of the three-dimensional simplified model of the fuselage barrel section. Preferably, the step 4 includes: Step 4-1: according to the assembly process plan, set the initial position of the simplified 3D model of the fuselage barrel section bottom bracket, and assemble the simplified 3D model of the fuselage barrel section bottom bracket and the simplified 3D model of the fuselage barrel section; In step 4-2, the constraint equation between the upper surface of the 3D simplified model of the fuselage barrel section bottom bracket and the lower surface of the 3D simplified model of the fuselage barrel section is: ; in, 、 、 Represent the three displacement components of the aircraft in the heading, span and gravity directions respectively; M and S They represent the upper surface of the three-dimensional simplified model of the fuselage barrel bottom bracket and the lower surface of the three-dimensional simplified model of the fuselage barrel, respectively. is the friction coefficient of the contact surface between the bracket and the fuselage barrel; Preferably, the step 5 has the following requirements: Step 5-1, applying gravity load to the simplified 3D model of the fuselage barrel bottom bracket and the simplified 3D model of the fuselage barrel; Step 5-2, solve by statics solution method and calculate the deformation results of the entire model under gravity load.

[0009] Preferably, the step six has the following requirements: Step 5-1, change the position of the simplified 3D model of the fuselage barrel bottom bracket; Step 5-2: Repeat step 5 to complete the calculation of stress and deformation results under different bracket support positions, and select the bracket support position corresponding to the minimum stress and deformation results as the optimal solution.

[0010] The beneficial effects of the present invention are: The present invention proposes a method for optimizing the support position of the bottom bracket of a fuselage barrel section. This method addresses the problem that traditional methods fail to consider the deformation of the fuselage barrel section itself, the interaction between the fuselage barrel section and the bracket, and local assembly deformation, which greatly differs from actual conditions and fails to accurately reflect the rationality of the bottom bracket support position, leading to fuselage barrel section deformation caused by unreasonable bottom bracket support position. The method can optimize the bottom bracket support position of the fuselage barrel section by considering the influence of fuselage barrel section weight, fuselage barrel section length, bracket support position, and bracket support number.

[0011] This optimization method can provide a theoretical basis for the design of the fuselage barrel bottom bracket support structure and assembly scheme design, avoiding the out-of-tolerance phenomenon caused by the unreasonable setting of the fuselage barrel bottom bracket position. It is an effective optimization method. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a flow chart of a method for optimizing the support position of the bottom bracket of a fuselage barrel section proposed by the present invention; Figure 2 The simplified three-dimensional model of the fuselage barrel section in step 1 and the simplified three-dimensional model of the fuselage barrel section bottom bracket in step 2 of the present invention; Figure 3 Dividing the three-dimensional simplified models into grids in step 3 of the present invention; Figure 4The deformation result is calculated in step 5 of the present invention; Explanation of the numbers in the figure: 1. Fuselage frame; 2. Skin; 3. Bottom plate beam; 4. Fuselage barrel bottom bracket; 5. Skin grid unit; 6. Fuselage barrel bottom bracket grid unit. DETAILED DESCRIPTION

[0013] The above background technology has already explained the importance of optimizing the support position of the fuselage barrel bottom bracket. However, traditional methods fail to account for the deformation of the fuselage barrel itself, the interaction between the fuselage barrel and the bracket, and local assembly deformation. These methods differ significantly from actual conditions and fail to accurately reflect the rationality of the bottom bracket support position, leading to problems with fuselage barrel deformation caused by improper bottom bracket support positioning.

[0014] To address the above-mentioned issues, an embodiment of the present invention proposes a method for optimizing the support position of the bracket at the bottom of the fuselage barrel section. This method can optimize the support position of the bracket at the bottom of the fuselage barrel section by taking into account the influence of the weight of the fuselage barrel section, the length of the fuselage barrel section, the support position of the bracket, and the number of bracket supports. This optimization method can provide a theoretical basis for the design of the support structure and assembly scheme of the bracket at the bottom of the fuselage barrel section, avoid the out-of-tolerance phenomenon caused by the unreasonable setting of the bracket position at the bottom of the fuselage barrel section, and is an effective optimization method. The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0015] like Figures 1-4 As shown, the present application provides a method for optimizing the support position of the bottom bracket of a fuselage barrel section, comprising the following steps: Step 1: Create a simplified 3D model of the fuselage barrel section and set the material performance parameters; Step 2: Establish a simplified three-dimensional model of the fuselage barrel bottom bracket and set the mechanical boundary conditions and material performance parameters; Step 3: Mesh the simplified 3D model of the fuselage barrel section and the simplified 3D model of the fuselage barrel section bottom bracket; Step 4: Set the initial position of the simplified 3D model of the fuselage barrel bottom bracket, complete the model assembly together with the simplified 3D model of the fuselage barrel, and set the constraint relationship; Step 5: Calculate the stress and deformation results of the bottom of the fuselage barrel section when the bracket is in the supported position. Step 6: Change the position of the simplified 3D model of the bracket at the bottom of the fuselage barrel section and repeat step 5 to complete the stress and deformation calculation results under different bracket support positions. Select the optimal bracket support position based on the results.

[0016] Among them, step one includes: Step 1-1, use CAE software to create a simplified 3D model of the fuselage barrel section, and at least retain the skin 1, fuselage frame 2, and bottom plate beam 3 in the model, such as Figure 2 As shown; Step 1-2: Set the Young's modulus, Poisson's ratio, and material density of the three-dimensional simplified structure of the fuselage barrel according to the actual material type. In this embodiment, they are all set to 70 GPa and 0.30, and the material density is 2.1×10 -9 t / mm 3 .

[0017] Among them, step 1-1 to the simplified 3D model of the fuselage barrel section has the following requirements: The weight, length, width and height of the simplified three-dimensional model of the fuselage barrel section are consistent with the actual dimensions.

[0018] Among them, step 2 includes: Step 2-1, use ABAQUS 6.13 finite element software to build a three-dimensional model of the fuselage barrel bottom bracket 4, as shown in Figure 2 As shown; Step 2-2: Set a 6-DOF constraint as a mechanical boundary condition on the lower surface of the simplified 3D model of the fuselage barrel bottom bracket. Step 2-3: According to the actual material type, set the Young's modulus, Poisson's ratio, and material density of the three-dimensional simplified model of the fuselage barrel bottom bracket; in this embodiment, the Young's modulus and Poisson's ratio are 210 GPa and 0.25 respectively, and the density is 7.8×10 -9 t / mm 3 Among them, step 2-1 to the simplified 3D model of the fuselage barrel bottom bracket has the following requirements: The contact area between the simplified 3D model of the fuselage barrel bottom bracket and the simplified 3D model of the fuselage barrel must be consistent with the actual object. Among them, step three has the following requirements: The three-dimensional simplified model of the fuselage barrel section bottom bracket and the three-dimensional simplified model of the fuselage barrel section are divided into grid units. It is required to check the sizes of all grid units. The minimum value of the three-dimensional simplified model of the fuselage barrel section bottom bracket shall not be less than the maximum value of the grid unit of the three-dimensional simplified model of the fuselage barrel section. For example, Figure 3 As shown; Among them, step four includes: Step 4-1: according to the assembly process plan, set the initial position of the simplified 3D model of the fuselage barrel section bottom bracket, and assemble the simplified 3D model of the fuselage barrel section bottom bracket and the simplified 3D model of the fuselage barrel section; In step 4-2, the constraint equation between the upper surface of the 3D simplified model of the fuselage barrel section bottom bracket and the lower surface of the 3D simplified model of the fuselage barrel section is: ; in, 、 、 Represent the three displacement components of the aircraft in the heading, span and gravity directions respectively; M and S They represent the upper surface of the three-dimensional simplified model of the fuselage barrel bottom bracket and the lower surface of the three-dimensional simplified model of the fuselage barrel, respectively. is the friction coefficient of the contact surface between the bracket and the fuselage barrel section. In this embodiment, , used to represent the effect of rubber on the actual surface of the bracket.

[0019] Among them, step five has the following requirements: Step 5-1, applying gravity load to the simplified 3D model of the fuselage barrel bottom bracket and the simplified 3D model of the fuselage barrel; Step 5-2, solve by statics solution method and calculate the deformation result of the whole model under gravity load, such as Figure 4 The deformation of the entire model under gravity load is calculated and the maximum deformation is 0.75 mm.

[0020] Among them, step six has the following requirements: Step 5-1, change the position of the simplified 3D model of the fuselage barrel bottom bracket; Step 5-2: Repeat step 5 to complete the calculation of stress and deformation results under different bracket support positions, and select the bracket support position corresponding to the minimum stress and deformation results as the optimal solution.

[0021] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A method for optimizing the support position of the bottom bracket of a fuselage barrel section, characterized in that: The method comprises the following steps: Step 1: Create a simplified 3D model of the fuselage barrel section and set the material performance parameters; Step 2: Establish a simplified three-dimensional model of the fuselage barrel bottom bracket and set the mechanical boundary conditions and material performance parameters; Step 3: Mesh the simplified 3D model of the fuselage barrel section and the simplified 3D model of the fuselage barrel section bottom bracket; Step 4: Set the initial position of the simplified 3D model of the fuselage barrel bottom bracket, complete the model assembly together with the simplified 3D model of the fuselage barrel, and set the constraint relationship; Step 5: Calculate the stress and deformation results of the bottom of the fuselage barrel section when the bracket is in the supported position. Step 6: Change the position of the simplified 3D model of the bracket at the bottom of the fuselage barrel section and repeat step 5 to complete the stress and deformation calculation results under different bracket support positions. Select the optimal bracket support position based on the results.

2. The method according to claim 1, characterized in that The step one comprises: Step 1-1: Use CAE software to create a simplified 3D model of the fuselage barrel section, retaining at least the skin, fuselage frame, and bottom plate beams; Step 1-2: Set the Young's modulus, Poisson's ratio, and material density of the three-dimensional simplified structure of the fuselage barrel section according to the actual material type used.

3. The method for optimizing the support position of the bottom bracket of the fuselage barrel section according to claim 2, characterized in that: The requirements for the simplified 3D model of the fuselage barrel section in step 1-1 are as follows: The weight, length, width and height of the simplified three-dimensional model of the fuselage barrel section are consistent with the actual dimensions.

4. The method according to claim 1, wherein The second step includes: Step 2-1: Create a simplified 3D model of the fuselage barrel bottom bracket using CAE software; Step 2-2: Set a 6-DOF constraint as a mechanical boundary condition on the lower surface of the simplified 3D model of the fuselage barrel bottom bracket. Step 2-3: According to the actual material type, set the Young's modulus, Poisson's ratio, and material density to establish the simplified three-dimensional model of the fuselage barrel bottom bracket.

5. The method according to claim 4, characterized in that The requirements for the simplified 3D model of the fuselage barrel bottom bracket in step 2-1 are as follows: The contact area between the three-dimensional simplified model of the fuselage barrel section bottom bracket and the three-dimensional simplified model of the fuselage barrel section is required to be consistent with the actual object.

6. The method according to claim 4, characterized in that Step 3 has the following requirements: The three-dimensional simplified model of the fuselage barrel section bottom bracket and the three-dimensional simplified model of the fuselage barrel section are divided into grid units, which requires that all grid unit sizes be checked, and the minimum value of the three-dimensional simplified model of the fuselage barrel section bottom bracket shall not be less than the maximum value of the grid unit of the three-dimensional simplified model of the fuselage barrel section.

7. The method according to claim 4, characterized in that The fourth step includes: Step 4-1: according to the assembly process plan, set the initial position of the simplified 3D model of the fuselage barrel section bottom bracket, and assemble the simplified 3D model of the fuselage barrel section bottom bracket and the simplified 3D model of the fuselage barrel section; In step 4-2, the constraint equation between the upper surface of the 3D simplified model of the fuselage barrel section bottom bracket and the lower surface of the 3D simplified model of the fuselage barrel section is: ； in, 、 、 Represent the three displacement components of the aircraft in the heading, span and gravity directions respectively; M and S They represent the upper surface of the three-dimensional simplified model of the fuselage barrel bottom bracket and the lower surface of the three-dimensional simplified model of the fuselage barrel, respectively. is the friction coefficient of the contact surface between the bracket and the fuselage barrel.

8. The method according to claim 2, characterized in that Step 5 has the following requirements: Step 5-1, applying gravity load to the simplified 3D model of the fuselage barrel bottom bracket and the simplified 3D model of the fuselage barrel; Step 5-2, solve by statics solution method and calculate the deformation results of the entire model under gravity load.

9. The method according to claim 2, characterized in that The step six has the following requirements: Step 5-1, change the position of the simplified 3D model of the fuselage barrel bottom bracket; Step 5-2: Repeat step 5 to complete the calculation of stress and deformation results under different bracket support positions, and select the bracket support position corresponding to the minimum stress and deformation results as the optimal solution.

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