Displacement-based middle fuselage cylinder section support height optimization method

Abstract

The invention provides a displacement-based middle fuselage cylinder section support height optimization method. The method comprises the steps of establishing a middle fuselage cylinder section finite element model; establishing a displacement boundary condition of the finite element model of the middle fuselage cylinder section; applying a load to the finite element model of the middle fuselage cylinder section, and solving a displacement field result of the finite element model of the middle fuselage cylinder section at a single support height; increasing the height of the middle fuselage tube section finite element model under the displacement boundary condition, and solving a displacement field result of the middle fuselage tube section finite element model under the supporting height; and establishing a displacement evaluation index, and evaluating the displacement field result under each supporting height to judge whether the supporting height of the middle fuselage meets the rigidity requirement or not. According to the method, the weight of the middle fuselage cylinder section, the length of the middle fuselage cylinder section, the geometrical characteristics of the section of the middle fuselage cylinder section and the height of the supporting position can be considered, and the supporting height of the middle fuselage cylinder section is rapidly calculated and optimized based on displacement.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft component assembly, and in particular relates to a displacement-based method for optimizing the support height of a mid-fuselage barrel section. Background Art

[0002] During the assembly of large fuselages, the mid-fuselage barrel section needs to be supported on a positioning device to maintain a specific position and posture, thereby completing the entire assembly process. Due to the weak rigidity and large size of the mid-fuselage barrel section, an inappropriate support position will cause significant assembly deformation. In order to ensure the assembly quality of the entire process, it is necessary to minimize the impact of assembly deformation in each assembly link of the mid-fuselage barrel section. Therefore, it is necessary to calculate the deformation results of the mid-fuselage barrel section under different support heights and quantify the impact of different support heights on the deformation of the mid-fuselage barrel section. Find the optimal support height to avoid assembly quality problems caused by unreasonable support height selection.

[0003] The traditional design method for the support height of the center fuselage barrel section is mainly to evaluate it from the perspective of process implementation applicability. It does not take into account the actual characteristics of the center fuselage barrel section, such as weak stiffness and large size, and does not take into account the spatial distribution of the support position. There is a big difference from the actual situation, which leads to inappropriate support position of the center fuselage barrel section, resulting in uncoordinated deformation of the entire center fuselage barrel section, resulting in significant local assembly deformation, and causing assembly quality problems. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem that the traditional design method does not take into account the actual characteristics of weak rigidity and large size of the middle fuselage barrel section, and does not take into account the spatial distribution of the support positions, which is quite different from the actual situation, resulting in inappropriate support positions of the middle fuselage barrel section, causing uncoordinated deformation of the entire middle fuselage barrel section, resulting in significant local assembly deformation, and causing assembly quality problems.

[0005] This application provides a displacement-based mid-fuselage barrel section support height optimization method, comprising:

[0006] Step 1: establishing a finite element model of the mid-fuselage barrel section, including: establishing a three-dimensional geometric model of the mid-fuselage and simplifying it to obtain a finite element model of the mid-fuselage barrel section;

[0007] Step 2: establishing the displacement boundary conditions of the finite element model of the middle fuselage barrel section;

[0008] Step 3: applying a load to the finite element model of the middle fuselage barrel section to solve the displacement field result of the finite element model of the middle fuselage barrel section at a single support height;

[0009] Step 4: Increase the height of the displacement boundary condition of the mid-fuselage barrel section finite element model and solve the displacement field result of the mid-fuselage barrel section finite element model at the support height;

[0010] Step 5: Establish a displacement evaluation index and evaluate the displacement field results at each support height to determine whether the support height of the middle fuselage barrel section meets the stiffness requirements.

[0011] Preferably, the step 1 includes:

[0012] Step 1-1: Use CAD software to create a 3D geometric model of the mid-fuselage. In this 3D geometric model, all parts except the fuselage frame, skin, and floor beam are deleted to form a simplified model of the mid-fuselage barrel section.

[0013] Steps 1-2: Set the Young's modulus, Poisson's ratio, and material density of the actual fuselage frame, skin, and floor beam based on the material type in the simplified model of the mid-fuselage barrel section.

[0014] Preferably, the simplified model of the middle fuselage barrel section obtained in step 1-1 has the following requirements:

[0015] The simplified model is required to have the same length, width and height as the actual fuselage barrel section, and the number and spacing of the fuselage frame, skin and bottom plate beams in the simplified model are required to be consistent with the actual fuselage.

[0016] Preferably, the second step includes:

[0017] Step 2-1: Select four curved surfaces A1, A2, A3, and A4 with a height of h1 on the outside of the simplified model of the middle fuselage barrel section to replace the outer support structure of the middle fuselage barrel section;

[0018] In step 2-2, three translational degrees of freedom constraints and three rotational degrees of freedom constraints are set for the four planes as the mechanical boundary conditions of the simplified model of the mid-fuselage barrel section.

[0019] Preferably, the step three includes:

[0020] Step 3-1, mesh each part included in the simplified model of the mid-fuselage barrel section. The maximum length, width, and height of the mesh unit of the simplified model of the mid-fuselage barrel section shall not exceed 20% of the length, width, and height of each part.

[0021] In step 3-2, a gravity load is applied to the simplified model of the entire mid-fuselage barrel section, and the displacement field of the simplified model of the mid-fuselage barrel section under the gravity load is calculated using the static solution method.

[0022] Preferably, the step 4 includes:

[0023] Step 4-1: Increase the height of the four curved surfaces A1, A2, A3, and A4 on the outer side of the simplified model of the middle fuselage barrel section with a height of h1 to h2;

[0024] Step 4-2, repeat step 3-2 to calculate the displacement field results of the simplified model of the middle fuselage barrel section at this time.

[0025] Preferably, the step five includes:

[0026] Step 5-1: For each support height, calculate the displacement field results of the simplified model of the mid-fuselage barrel section;

[0027] Step 5-2: For each support height, a statistical algorithm is used to obtain the maximum displacement u of all mesh elements in the simplified model of the middle fuselage barrel section. max As a stiffness index for the simplified model of the mid-fuselage barrel section;

[0028] Preferably, the displacement field results obtained at each support height in step 5-2 meet the following requirements:

[0029] It is required to include at least 5 groups of displacement field data of the simplified model of the middle fuselage barrel section at different heights, and select the displacement field u of each group of simplified model of the middle fuselage barrel section max The minimum value among them is recorded, and its corresponding support height is taken as the optimal value of the middle fuselage support height.

[0030] The beneficial effects of the present invention are:

[0031] An embodiment of the present invention proposes a displacement-based mid-fuselage barrel section support height optimization method. Specifically, by solving the displacement field results of the mid-fuselage barrel section finite element model at a single support height, combined with a displacement evaluation index, the displacement field results at different support heights are evaluated to obtain the optimal value of the mid-fuselage support height.

[0032] This method takes into account the center fuselage weight, length, cross-sectional geometry, and support height, rapidly calculating and optimizing the center fuselage support height based on displacement. The developed optimization method minimizes deformation caused by inappropriate center fuselage support height, further improving assembly quality. It is a fast and effective optimization method. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a flow chart of a displacement-based mid-fuselage barrel section support height optimization method proposed in the present invention;

[0034] Figure 2 The finite element model of the middle fuselage barrel section in step 1 of the present invention;

[0035] Figure 3 The mesh unit model of the finite element in step 3 of the present invention;

[0036] Figure 4 is the displacement result calculated in step 4 of the present invention;

[0037] Figure 5 is the maximum deformation value of the middle fuselage barrel section at each support height calculated in step 5 of the present invention;

[0038] Explanation of the numbers in the figure: 1. fuselage frame; 2. skin; 3. bottom plate beam; 4. grid unit of fuselage frame; 5. grid unit of skin; 6. grid unit of bottom plate beam. DETAILED DESCRIPTION

[0039] The above background technology has already explained the importance of selecting an appropriate support height during the assembly of the mid-fuselage barrel. However, conventional methods for calculating the support height of the mid-fuselage barrel fail to consider the weak rigidity and large size of the actual mid-fuselage barrel, nor the spatial distribution of the support positions, resulting in significant discrepancies with actual conditions. This results in inappropriate support positions for the mid-fuselage barrel, causing uncoordinated deformation of the entire mid-fuselage barrel, significant local assembly deformation, and assembly quality issues.

[0040] To address the above issues, embodiments of the present invention propose a displacement-based mid-fuselage barrel section support height optimization method. This method solves the displacement field of a mid-fuselage barrel section finite element model at a single support height and, combined with a displacement evaluation index, evaluates the displacement field results at different support heights to determine the optimal mid-fuselage support height. The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] like Figure 1-Figure 5 As shown, the present application provides a displacement-based mid-fuselage barrel section support height optimization method, comprising the following steps:

[0042] Step 1: establishing a finite element model of the mid-fuselage barrel section, including: establishing a three-dimensional geometric model of the mid-fuselage and simplifying it to obtain a finite element model of the mid-fuselage barrel section;

[0043] Step 2: establishing the displacement boundary conditions of the finite element model of the middle fuselage barrel section;

[0044] Step 3: applying a load to the finite element model of the middle fuselage barrel section to solve the displacement field result of the finite element model of the middle fuselage barrel section at a single support height;

[0045] Step 4: Increase the height of the displacement boundary condition of the mid-fuselage barrel section finite element model and solve the displacement field result of the mid-fuselage barrel section finite element model at the support height;

[0046] Step 5: Establish a displacement evaluation index and evaluate the displacement field results at each support height to determine whether the support height of the middle fuselage barrel section meets the stiffness requirements.

[0047] Among them, step one includes:

[0048] Step 1-1, use CATIAV5 R28 software to build a 3D geometric model of the mid-fuselage. In the 3D geometric model, delete all parts except the fuselage frame 1, skin 2, and bottom plate beam 3 to form a simplified model of the mid-fuselage barrel section, as shown in the following figure: Figure 2 As shown;

[0049] Step 1-2: According to the material type in the simplified model of the middle fuselage barrel section, set the Young's modulus, Poisson's ratio, and material density of the actual fuselage frame, skin, and bottom plate beam. 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

[0050] The simplified model of the mid-fuselage barrel section obtained in step 1-1 has the following requirements:

[0051] The simplified model is required to have the same length, width and height as the actual fuselage barrel section, and the number and spacing of the fuselage frame, skin and bottom plate beams in the simplified model are required to be consistent with the actual fuselage.

[0052] Among them, step 2 includes:

[0053] Step 2-1: In ABAQUS 6.13 finite element software, select four curved surfaces A1, A2, A3, and A4 with a height of h1 on the outside of the simplified model of the mid-fuselage barrel section to replace the outer support structure of the mid-fuselage barrel section. In this embodiment, the initial h1 is set to 1000 mm.

[0054] In step 2-2, three translational degrees of freedom constraints and three rotational degrees of freedom constraints are set for the four planes as the mechanical boundary conditions of the simplified model of the mid-fuselage barrel section.

[0055] Among them, step three includes:

[0056] Step 3-1, divide each part contained in the simplified model of the middle fuselage barrel section into grid units. The maximum length, width and height of the grid unit of the simplified model of the middle fuselage barrel section shall not exceed 20% of the length, width and height of each part, such as Figure 3 As shown;

[0057] Step 3-2, apply gravity load to the simplified model of the entire mid-fuselage barrel section, and solve it using the statics solution method to calculate the displacement field results of the simplified model of the mid-fuselage barrel section under gravity load, such as Figure 4 shown.

[0058] Among them, step four includes:

[0059] Step 4-1: Increase the height of the four curved surfaces A1, A2, A3, and A4 on the outer side of the simplified model of the middle fuselage barrel section with a height of h1 to h2. In this embodiment, h2 is set to 1200 mm.

[0060] Step 4-2, repeat step 3-2 to calculate the displacement field results of the simplified model of the middle fuselage barrel section at this time.

[0061] Among them, step five includes:

[0062] Step 5-1: For each support height, calculate the displacement field results of the simplified model of the mid-fuselage barrel section;

[0063] Step 5-2: For each support height, a statistical algorithm is used to obtain the maximum displacement u of all mesh elements in the simplified model of the middle fuselage barrel section. max As a stiffness index for the simplified model of the mid-fuselage barrel section;

[0064] The displacement field results obtained at each support height in step 5-2 have the following requirements:

[0065] It is required to include at least 5 groups of displacement field data of the simplified model of the middle fuselage barrel section at different heights, and select the displacement field u of each group of simplified model of the middle fuselage barrel section max The minimum value among them is recorded as the corresponding support height, which is the optimal value of the middle fuselage support height. In this embodiment, the five groups of heights are 1000mm, 1200mm, 1400mm, 1600mm, and 1800mm respectively. The calculated u max like Figure 5 As shown in the figure, the optimal value of the mid-fuselage support height is 1800mm.

[0066] 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 displacement-based mid-fuselage barrel section support height optimization method, characterized in that: The method comprises the following steps: Step 1: establishing a finite element model of the mid-fuselage barrel section, including: establishing a three-dimensional geometric model of the mid-fuselage and simplifying it to obtain a finite element model of the mid-fuselage barrel section; Step 2: establishing the displacement boundary conditions of the finite element model of the middle fuselage barrel section; Step 3: applying a load to the finite element model of the middle fuselage barrel section to solve the displacement field result of the finite element model of the middle fuselage barrel section at a single support height; Step 4: Increase the height of the displacement boundary condition of the mid-fuselage barrel section finite element model and solve the displacement field result of the mid-fuselage barrel section finite element model at the support height; Step 5: Establish a displacement evaluation index and evaluate the displacement field results at each support height to determine whether the support height of the middle fuselage barrel section meets the stiffness requirements.

2. The displacement-based mid-fuselage barrel section support height optimization method according to claim 1, characterized in that: The step one comprises: Step 1-1: Use CAD software to create a 3D geometric model of the mid-fuselage. In this 3D geometric model, all parts except the fuselage frame, skin, and floor beam are deleted to form a simplified model of the mid-fuselage barrel section. In steps 1-2, according to the material type in the simplified model of the mid-fuselage barrel section, set the Young's modulus, Poisson's ratio, and material density of the actual fuselage frame, skin, and bottom plate beam.

3. The displacement-based mid-fuselage barrel section support height optimization method according to claim 2, characterized in that: The simplified model of the middle fuselage barrel section obtained in step 1-1 has the following requirements: The simplified model is required to have the same length, width and height as the actual fuselage barrel section, and the number and spacing of the fuselage frame, skin and bottom plate beams in the simplified model are required to be consistent with the actual fuselage.

4. The displacement-based mid-fuselage barrel section support height optimization method according to claim 1, characterized in that: The second step includes: Step 2-1: Select four curved surfaces A1, A2, A3, and A4 with a height of h1 on the outside of the simplified model of the middle fuselage barrel section to replace the outer support structure of the middle fuselage barrel section; In step 2-2, three translational degrees of freedom constraints and three rotational degrees of freedom constraints are set for the four planes as the mechanical boundary conditions of the simplified model of the mid-fuselage barrel section.

5. The displacement-based mid-fuselage barrel section support height optimization method according to claim 2, characterized in that: The step three includes: Step 3-1, mesh each part included in the simplified model of the mid-fuselage barrel section. The maximum length, width, and height of the mesh unit of the simplified model of the mid-fuselage barrel section shall not exceed 20% of the length, width, and height of each part. In step 3-2, a gravity load is applied to the simplified model of the entire mid-fuselage barrel section, and the displacement field of the simplified model of the mid-fuselage barrel section under the gravity load is calculated using the static solution method.

6. The displacement-based mid-fuselage barrel section support height optimization method according to claim 5, characterized in that: The fourth step includes: Step 4-1: Increase the height of the four curved surfaces A1, A2, A3, and A4 on the outer side of the simplified model of the middle fuselage barrel section with a height of h1 to h2; Step 4-2, repeat step 3-2 to calculate the displacement field results of the simplified model of the middle fuselage barrel section at this time.

7. The displacement-based mid-fuselage barrel section support height optimization method according to claim 1, characterized in that: The step five includes: Step 5-1: For each support height, calculate the displacement field results of the simplified model of the mid-fuselage barrel section; Step 5-2: For each support height, a statistical algorithm is used to obtain the maximum displacement u of all mesh elements in the simplified model of the middle fuselage barrel section. max As the stiffness index of the simplified model of the mid-fuselage barrel section.

8. The displacement-based mid-fuselage barrel section support height optimization method according to claim 7, characterized in that: The displacement field results obtained in step 5-2 at each support height have the following requirements: It is required to include at least 5 groups of displacement field data of the simplified model of the middle fuselage barrel section at different heights, and select the displacement field u of each group of simplified model of the middle fuselage barrel section max The minimum value among them is recorded, and its corresponding support height is taken as the optimal value of the middle fuselage support height.

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