Aircraft skin assembly deformation suppression method based on stress field regulation and control

Abstract

The invention provides an aircraft skin assembly deformation suppression method based on stress field regulation and control, and belongs to the technical field of aircraft assembling.The aircraft skin assembly deformation suppression method comprises the steps that skin parameters and riveting parameters are collected, and trigger conditions are set; establishing a three-dimensional stress displacement field model based on a thin plate theory for the skin meeting the triggering condition, and performing simulation calculation to obtain a non-riveting area displacement field distribution diagram and a stress gradient distribution diagram; a high-risk area judgment model is established, and a high-risk area prone to deformation is delimited through simulation calculation according to the stress gradient; determining an adhesive tape laying scheme and laying an adhesive tape in the high-risk area; and riveting operation is conducted on the skin, real-time pretension is monitored, a real-time pretension grading interval is divided, corresponding adjustment measures are taken according to the real-time pretension, riveting operation continues to be conducted, and skin assembling is completed. By the adoption of the method, the deformation amount of the non-riveting area of the skin can be controlled within an extremely small range, and the high-precision requirement of aircraft assembly is met.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft assembly, and relates to a method for suppressing aircraft skin assembly deformation based on stress field regulation. Background Art

[0002] In the existing aircraft skin assembly, the control methods for the deformation of the non-connected area after riveting mainly include:

[0003] (1) Traditional process compensation method: adding temporary weight or local heating in the deformation area through manual experience, but it has problems such as low efficiency (single piece takes ≥ 2h) and unstable effect (bulge height fluctuates more than ±0.5mm).

[0004] (2) Structural reinforcement method: For example, the invention patent with publication number US20180105221A1 proposes to control deformation by adding reinforcing rivets. Although it can reduce the deformation by 15%-20%, it will increase the weight of the structure (about 3.5kg / m 2 ) and stress concentration.

[0005] (3) Active control method: For example, the invention patent with publication number EP3561081B1 uses a piezoelectric actuator to apply reverse deformation, but requires a complex control system (cost increase of US$12,000 / station) and is highly temperature sensitive (performance drops by 40% at 80°C).

[0006] Most of the existing process optimization methods are based on experience and trial and error, lacking a comprehensive and in-depth analysis of the internal stress field of the skin, and unable to accurately predict the specific location and extent of bulging or denting in the non-riveted area of ​​the skin under different riveting parameters and skin structure combinations. This makes the preventive measures lack of pertinence and it is difficult to fundamentally solve the deformation problem. The main problems include:

[0007] (1) There is a lack of quantitative analysis of the skin stress field, and the intervention measures are out of touch with the mechanical mechanism;

[0008] (2) The stiffness matching problem is not solved, and the additional structure is prone to cause secondary stress concentration;

[0009] (3) Insufficient control accuracy (angle deviation > 30°, tension fluctuation > 20%). Summary of the invention

[0010] In order to solve the above problems existing in the prior art, the present invention provides a method for suppressing aircraft skin assembly deformation based on stress field regulation. The trigger conditions and the corresponding critical stress gradient values ​​are determined according to the skin material. When the trigger conditions are met, the three-dimensional stress displacement field modeling is triggered. When the adjacent stress gradient value is exceeded, it is determined to be a high-risk area. The skin deformation amplitude is calculated to determine the tape laying plan and lay the tape. The pre-tension during the riveting process is monitored in real time, and secondary stacking can be performed when the limit is exceeded. By adopting the method of the present invention, the deformation amount of the non-riveted area of ​​the skin can be controlled within a very small range, meeting the high-precision requirements of aircraft assembly.

[0011] The technical solution of the present invention is as follows:

[0012] A method for suppressing deformation of aircraft skin assembly based on stress field regulation includes: collecting relevant parameters of the skin to be assembled and riveting parameters, and setting trigger conditions; for the skin that meets the trigger conditions, a three-dimensional stress displacement field model is established based on the thin plate theory, and the displacement field distribution map and stress gradient distribution map of the non-riveted area are obtained through simulation calculation; a high-risk area determination model is established, and high-risk areas prone to deformation are delineated through simulation calculation based on the stress gradient; a tape laying plan is determined and tape is laid in the high-risk area; the skin is riveted, and the real-time pre-tension is monitored, the real-time pre-tension is divided into grading intervals, and corresponding adjustment measures are taken according to the real-time pre-tension, and the riveting operation is continued to complete the skin assembly. Specifically, the following steps are included:

[0013] Step 1, Data Collection:

[0014] The material properties of the skin to be assembled, the skin thickness h and the riveting parameters are collected. The material properties of the skin include the elastic modulus E and Poisson's ratio ν (the ratio of the lateral contraction to the longitudinal stretching of the skin), and the riveting parameters include the rivet spacing and the riveting force of various fasteners required for the skin to be assembled.

[0015] Step 2: Determine the triggering conditions:

[0016] The trigger conditions are set according to the historical experience data of various types of skins. The trigger conditions include the rivet spacing trigger value and the skin thickness trigger value. The corresponding trigger conditions are selected according to the type of skin to be assembled. If the rivet spacing of the skin to be assembled is greater than the rivet spacing trigger value or the skin thickness is less than the skin thickness trigger value, it is determined that the trigger conditions are met and step 3 is executed; for the skin that does not meet the trigger conditions, the riveting assembly process is directly entered to complete the riveting assembly operation.

[0017] Step 3: Establish a three-dimensional stress-displacement field model and perform simulation:

[0018] In the aircraft coordinate system (i.e., the aircraft heading is the X-axis, the wing span direction is the Y-axis, and the normal direction of the XY plane is the Z-axis), the three-dimensional stress-displacement field control equation is established based on the thin plate theory, such as formula (1) (fourth-order partial differential equation). Based on the three-dimensional stress-displacement field control equation, a three-dimensional stress-displacement field model is established to describe the deformation of the skin under the action of riveting force and internal stress:

[0019]

[0020] Where D is the skin stiffness, that is, the ability of the skin itself to resist bending deformation. Calculation; w is the deflection function, that is, the vertical displacement of the skin at any position (x, y) under the action of the load; q(x, y) is the lateral load at the position (x, y), that is, the distributed force acting on the skin surface and perpendicular to the skin surface driving the deformation; N x is the normal stress along the X direction; N y is the normal stress along the Y direction; N xy is the shear stress in the XY plane; and They respectively represent the curvature changes of the skin in the X and Y directions caused by the load. The positive curvature indicates that the skin bulges, and the negative curvature indicates that the skin is concave. and They represent the correction of the in-plane stress to the skin stiffness. The in-plane stress includes N x and N y .

[0021] The left side of the equation in formula (1) represents the ability of the skin stiffness to suppress deformation, and the right side of the equation represents the external factors that drive the skin deformation, including the lateral load and the in-plane stress. The two factors jointly determine the final deformation and stress distribution of the skin. Therefore, formula (1) reflects the dynamic balance between the skin stiffness and the external load.

[0022] The boundary conditions of the three-dimensional stress-displacement field model are set, specifically: ① the skin thickness is less than the skin thickness trigger value, ② the rivet spacing is greater than or equal to the rivet spacing trigger value, ③ the riveting force range boundary is set according to the skin type, and the riveting forces of various fasteners collected in step 1 must be within the riveting force range boundary. When any of the above conditions is not met, the three-dimensional stress-displacement field model fails. When conditions ① or ② are not met, it means that the skin to be assembled can directly enter the riveting assembly process. For the skin to be riveted that does not meet condition ③, the skin deformation cannot be suppressed by this method.

[0023] The three-dimensional stress-displacement field model is simulated by finite element analysis software, and equation (1) is solved to calculate the displacement (representing the deformation at each position) and stress gradient of each position in the non-riveted area of ​​the skin to be assembled, and the displacement field distribution diagram and stress gradient distribution diagram of the non-riveted area are obtained.

[0024] Step 4, mark high risk areas:

[0025] According to the material properties of the skin to be assembled collected in step 1, the critical stress gradient is selected. The critical stress gradient is determined based on the historical experience of the properties of different types of aircraft skin products. The stress gradient refers to the rate of change of stress with space, which is a key indicator for judging the risk of local deformation. Construct a high-risk area determination model that is prone to deformation:

[0026]

[0027] In the formula, σ x and σ y are the microscopic stresses in the X and Y directions at any position (x, y) on the skin, σ x With N x The relationship is: σ y With N y The relationship is:

[0028] The high-risk area determination model is simulated by finite element analysis software, and the areas in the stress gradient distribution diagram that exceed the critical stress gradient of the skin to be assembled are defined as high-risk areas prone to deformation and marked in red.

[0029] Step 5, tape laying parameter design and tape laying:

[0030] According to formula (1), the equivalent bending resistance of the skin can be dynamically adjusted by adjusting the in-plane stress, so that the skin exhibits stronger anti-deformation and anti-buckling performance under external loads. The in-plane stress can be adjusted by laying tape on the skin surface, that is, by adjusting the preload force F applied to the skin after laying the tape. pre To suppress skin deformation, this control method does not increase the stiffness D of the skin itself, but achieves deformation suppression through mechanical balance.

[0031] According to the simulation results in step 3, determine the required preload F pre The range of the required tape pretension σ is determined pre Select the appropriate tape type within the range.

[0032] Use formula (3) to calculate the tape width b:

[0033]

[0034] Determine the tape laying direction based on the energy functional minimization principle:

[0035]

[0036] Where θ is the laying angle, that is, the angle between the tape laying direction and the X-axis; τ xy is the microscopic shear force in the XY plane.

[0037] Determine the tape laying plan based on the tape width and tape laying direction, and lay the tape in the high-risk area designated in step 4 according to the tape laying plan. The laying process is as follows: mark the tape sticking position and direction on the surface of the skin to be assembled, and use manual laying or sticking equipment to accurately lay the tape in the high-risk area.

[0038] Step 6: Real-time stress monitoring and hierarchical regulation:

[0039] The strain gauges are pasted in an array on the tape laid in the high-risk area. The skin to be assembled is riveted, and the strain gauges are used to collect the skin displacement in real time during the riveting process, and σ is calculated based on the skin displacement. x , σ y and τ xy According to the equivalent stress principle, the real-time pretension is calculated using formula (5)

[0040]

[0041] Divide the real-time pre-tensioning grading intervals and take corresponding adjustment measures:

[0042] 1) If Then maintain the current state and continue the riveting operation until the skin assembly is completed, where σ yield Represents the yield strength of the skin material.

[0043] 2) If The riveting operation is paused and the Reselect σ pre The type of tape with a higher value, where ΔT is the pre-tension adjustment; Kp is the proportional coefficient, which is empirical data; after removing the laid tape, σ pre The higher value tape is laid in the high-risk area according to the original laying plan. After the tape is re-laid, the riveting operation continues and the skin assembly is finally completed.

[0044] 3) If The riveting operation is suspended, and the original tape is used on the already laid tape in the high-risk area to lay the second layer of tape along the principal stress direction, which is obtained by the simulation calculation in step 3. After the second layer of tape is laid, the riveting operation is continued to complete the skin assembly.

[0045] The beneficial effects of the present invention are:

[0046] (1) Effectively suppress deformation: The present invention can significantly reduce the probability of bulging or denting in the non-riveted area of ​​the aircraft skin after riveting assembly by accurately analyzing the three-dimensional stress displacement field and rationally formulating and implementing the tape laying plan before assembly. A large amount of experimental data and practical application cases show that after adopting the method of the present invention, the deformation of the non-riveted area of ​​the skin can be controlled within a very small range, meeting the high-precision requirements of aircraft assembly.

[0047] (2) Improve assembly quality and efficiency: Since the present invention can predict and prevent deformation problems in advance, it avoids a lot of rework and delays caused by traditional post-detection and repair. In actual production, it can reduce the adjustment and repair time during the assembly process, improve the overall assembly efficiency, and at the same time improve the assembly quality of the aircraft, ensuring the integrity and safety of the aircraft structure.

[0048] (3) Reduce costs: The present invention reduces assembly rework and scrapping caused by skin deformation, and reduces material and labor costs. In addition, by optimizing the tape laying scheme and selecting a suitable laying method, the amount of material used is reasonably controlled while ensuring the effect, further reducing costs.

[0049] (4) Enhanced adaptability and versatility: By adjusting the input parameters of the three-dimensional stress-displacement field model and the parameters in the calculation formula related to the tape laying scheme, the present invention can be applied to the skin assembly of large civil aircraft of different models and structures, and can provide personalized deformation suppression solutions for various complex assembly situations, thus having broad application prospects.

[0050] In summary, the present invention triggers stress-displacement field modeling from geometric and mechanical conditions, realizes the design of tape laying scheme and dynamic tension control, and forms a complete closed loop. The skin bulge height reduction rate is 75%-82% (from the typical value of deformation 0.5-1.2mm to 0.03-0.05mm), and the stress uniformity is improved: the coefficient of variation is reduced from 0.38 to 0.12, and the efficiency and quality of aircraft skin assembly riveting are greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a flow chart of the scheme of the present invention.

[0052] Figure 2 The displacement field distribution diagram of the non-riveted area, where (a) is the displacement field distribution diagram of the non-riveted area, and (b) is the riveted point position diagram.

[0053] Figure 3 Identify areas of view for high risk. DETAILED DESCRIPTION

[0054] The technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments improved or adjusted by ordinary technicians in the field based on the embodiments of the present invention belong to the protection scope of the present invention.

[0055] This embodiment takes the aluminum alloy skin of a certain type of aircraft as an example to provide a clear and complete description of the method process of the present invention.

[0056] A method for suppressing aircraft skin assembly deformation based on stress field regulation, the process is as follows Figure 1 As shown, the following steps are included:

[0057] Step 1, Data Collection:

[0058] The material properties of the aluminum alloy skin, skin thickness h and riveting parameters are collected. The material properties of the skin include elastic modulus E and Poisson's ratio ν, and the riveting parameters include riveting spacing and riveting forces of various fasteners.

[0059] Step 2: Determine the triggering conditions:

[0060] The trigger conditions are set based on the historical experience data of various types of skins. Aircraft skins are thin plate parts. According to the historical test data of aluminum alloy skins, when the rivet point spacing is greater than 50mm or the skin thickness is less than 2mm, the skin support stiffness will decrease by 40%, and deformation is likely to occur. The trigger conditions are set as shown in Table 1:

[0061] Table 1: Trigger conditions

[0062]

[0063] If the riveting spacing of the aluminum alloy skin is greater than 50 mm or the skin thickness is less than 2 mm, it is determined that the trigger condition is met and step 3 is executed. For the aluminum alloy skin that does not meet the trigger condition, the riveting assembly process is directly entered to complete the riveting assembly operation.

[0064] Step 3: Establish a three-dimensional stress-displacement field model and perform simulation:

[0065] The three-dimensional stress-displacement field control equation is established based on the thin plate theory, as shown in equation (1).

[0066] In the aircraft coordinate system (i.e., the coordinate system is established with the aircraft heading as the X-axis, the wing span direction as the Y-axis, and the normal of the XY plane as the Z-axis), the three-dimensional stress-displacement field control equation is established based on the thin plate theory, that is, the thin plate equation is as shown in formula (1). Based on the three-dimensional stress-displacement field control equation, a three-dimensional stress-displacement field model is established to describe the deformation of the skin under the action of riveting force and internal stress.

[0067] The left side of the equation in formula (1) represents the ability of the skin stiffness to suppress deformation, and the right side of the equation represents the external factors that drive the skin deformation, including the lateral load and the in-plane stress. The two factors jointly determine the final deformation and stress distribution of the skin. Therefore, formula (1) reflects the dynamic balance between the skin stiffness and the external load.

[0068] The boundary conditions of the three-dimensional stress-displacement field model are set, specifically: ① the skin thickness is less than 2 mm, ② the riveting spacing is greater than 50 mm, ③ the lower boundary of the riveting force range of the aluminum alloy skin is set to 1.25 KN, and the upper boundary is set to 6.8 KN. The riveting forces of various fasteners collected in step 1 must be greater than or equal to 1.25 KN and less than or equal to 6.8 KN; when any of the above conditions is not met, the three-dimensional stress-displacement field model fails. When conditions ① or ② are not met, it means that the aluminum alloy skin can directly enter the riveting assembly process. For aluminum alloy skins that do not meet condition ③, the skin deformation cannot be suppressed by this method.

[0069] In order to simplify the three-dimensional stress-displacement field model, in this embodiment, the skin curvature is ignored, the aluminum alloy skin is simplified to a flat plate, and the riveting state in the model is simplified to a rectangular symmetrical riveting, that is, the riveting points in each riveting area are simplified to a rectangular distribution (such as Figure 2 In (b), we have Where A is the unit cross-sectional area, and A = h; since N x =N y , the shear forces in the X and Y directions cancel each other out, so N xy =0, that is, no shear stress is generated in the XY plane.

[0070] The three-dimensional stress-displacement field model is simulated by finite element analysis software, and equation (1) is solved to calculate the displacement and stress gradient of each position in the non-riveted area of ​​the aluminum alloy skin, and the displacement field distribution diagram of the non-riveted area is obtained (such as Figure 2 (a)) and stress gradient distribution diagram.

[0071] Step 4, mark high risk areas:

[0072] According to the material properties of the aluminum alloy skin collected in step 1, the critical stress gradient is selected. The critical stress gradient is determined based on the historical experience values ​​of the properties of different types of aircraft skin products. The critical stress gradient values ​​of aluminum alloy skin and carbon fiber composite skin are shown in Table 2. When the stress gradient in a certain area exceeds the critical stress gradient, it indicates that there is a severe stress concentration in this area, which is easy to cause bulging or depression:

[0073] Table 2: Critical stress gradients

[0074] Material Type Critical stress gradient (MPa / mm) Aluminum Alloy 25 Carbon fiber composites 35

[0075] Using the critical stress gradient of the aluminum alloy skin, a high-risk area determination model prone to deformation is constructed as follows:

[0076]

[0077] The high-risk area determination model is simulated by finite element analysis software, and the area in the stress gradient distribution diagram that exceeds the critical stress gradient of the aluminum alloy skin is defined as a high-risk area prone to deformation and marked in red. Figure 3 shown.

[0078] Step 5, tape laying parameter design and tape laying:

[0079] According to formula (1), the equivalent bending resistance of the skin can be dynamically adjusted by adjusting the in-plane stress, so that the skin exhibits stronger anti-deformation and anti-buckling performance under external loads. The in-plane stress can be adjusted by laying tape on the skin surface, that is, by adjusting the preload force F applied to the skin after laying the tape. pre To suppress skin deformation, this control method does not increase the stiffness D of the skin itself, but achieves deformation suppression through mechanical balance.

[0080] According to the simulation results in step 3, determine the required preload F pre The range of the required tape pretension σ is determined pre The selection range is σ pre ∈[5,15]MPa, select aluminum alloy platinum tape within this range.

[0081] The tape width b is calculated using formula (3) to be 400 mm.

[0082] According to the principle of energy functional minimization, the laying angle θ is calculated using formula (4) to determine the laying direction of the tape. Since the riveting state in the three-dimensional stress displacement field model is simplified to a symmetrical riveting of a rectangular shape, τ xy =0, the laying angle θ can be simplified to 45°.

[0083] Determine the tape laying plan based on the tape width and tape laying direction, mark the tape sticking position and direction on the aluminum alloy skin surface, and use manual laying to accurately lay the aluminum alloy platinum tape in the high-risk area designated in step 4.

[0084] Step 6: Real-time stress monitoring and hierarchical regulation:

[0085] The strain gauges are pasted in an array on the tape laid in the high-risk area. The aluminum alloy skin is riveted, and the skin displacement during the riveting process is collected in real time using the strain gauges. The sampling rate is 1kHz, and σ is calculated based on the skin displacement. x , σ y and τxy According to the equivalent stress principle, the real-time pretension is calculated using formula (5)

[0086] Divide the real-time pre-tensioning grading intervals and take corresponding adjustment measures:

[0087] 1) If The current state is maintained and the riveting operation is continued. The σ yield It is 325MPa.

[0088] 2) If The riveting operation is paused and the Reselect σ pre The type of tape with a higher value is selected. For aluminum alloy skin, Kp is generally selected as 0.4. After removing the laid tape, σ pre The higher value tape is laid in the high-risk area according to the original laying plan. After the tape is re-laid, the riveting operation continues and the skin assembly is finally completed.

[0089] 3) If The riveting operation is suspended, and the aluminum alloy platinum tape is also used on the tape already laid in the high-risk area to lay the second layer of tape along the principal stress direction. The principal stress direction is obtained by the simulation calculation in step 3, and the model is simplified. After the second layer of tape is laid, the riveting operation is continued to complete the skin assembly.

[0090] In this embodiment, the real-time pretension In interval 2), the adjustment measure of replacing the tape is adopted, and the laid aluminum alloy platinum tape is replaced with carbon fiber reinforced epoxy tape, which has a higher elastic modulus and a stronger inhibitory effect.

[0091] After the deformation of the aluminum alloy skin riveting process was suppressed by the method of this embodiment, the surface waviness was checked and the quality met the tolerance requirement of 0.015 mm.

[0092] The above-described embodiments merely express the implementation methods of the present invention, but they should not be understood as limiting the scope of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for suppressing aircraft skin assembly deformation based on stress field regulation, characterized in that: include: Collect the skin-related parameters and riveting parameters to be assembled, and set the trigger conditions; For the skin that meets the triggering conditions, a three-dimensional stress-displacement field model is established based on the thin plate theory, and the displacement field distribution diagram and stress gradient distribution diagram of the non-riveted area are obtained through simulation calculation; Establish a high-risk area determination model, and define high-risk areas prone to deformation based on stress gradients through simulation calculations; Determine the tape laying plan and lay the tape in high-risk areas; Perform riveting operations on the skin, monitor the real-time pre-tension, divide the real-time pre-tension into grading intervals, take corresponding adjustment measures based on the real-time pre-tension, continue the riveting operation and complete the skin assembly.

2. The method for suppressing aircraft skin assembly deformation based on stress field regulation according to claim 1 is characterized in that: The specific steps include: Step 1, data collection: Collect the material properties of the skin to be assembled, the skin thickness h and the riveting parameters, wherein the material properties of the skin include the elastic modulus E and the Poisson's ratio ν, and the riveting parameters include the riveting spacing and the riveting force of various fasteners required for the skin to be assembled; Step 2: Determine the triggering conditions: Set trigger conditions, which include riveting spacing trigger value and skin thickness trigger value. If the riveting spacing of the skin to be assembled is greater than the riveting spacing trigger value or the skin thickness is less than the skin thickness trigger value, it is determined that the trigger conditions are met and step 3 is executed; if the trigger conditions are not met, the riveting assembly process is directly entered to complete the riveting assembly operation; Step 3: Establish a three-dimensional stress-displacement field model and perform simulation: In the aircraft coordinate system, the three-dimensional stress-displacement field control equation is established based on the thin plate theory as shown in formula (1), and the three-dimensional stress-displacement field model is established based on the three-dimensional stress-displacement field control equation: Where D is the skin stiffness; w is the deflection function, that is, the vertical displacement of the skin at any position (x, y) under the action of the load; q(x, y) is the lateral load at the position (x, y); N x is the normal stress along the X direction; N y is the normal stress along the Y direction; N xy is the shear stress in the XY plane; and They respectively represent the curvature changes in the X and Y directions caused by the skin under load; and They represent the correction of the in-plane stress to the skin stiffness. The in-plane stress includes N x and N y ; Formula (1) reflects the dynamic balance between skin stiffness and external load; Setting the boundary conditions of the three-dimensional stress-displacement field model; simulating the three-dimensional stress-displacement field model, and solving equation (1), calculating the displacement and stress gradient of each position in the non-riveted area of ​​the skin to be assembled, and obtaining the displacement field distribution diagram and stress gradient distribution diagram of the non-riveted area; Step 4, mark high risk areas: Determine the critical stress gradient and build a model for determining high-risk areas prone to deformation: In the formula, σ x and σ y are the microscopic directional stresses in the X and Y directions at any position (x, y) on the skin, respectively; The high-risk area determination model is simulated, and the area in the stress gradient distribution diagram that exceeds the critical stress gradient of the skin to be assembled is defined as a high-risk area prone to deformation and marked; Step 5, tape laying parameter design and tape laying: According to formula (1), the equivalent bending capacity of the skin can be dynamically adjusted by adjusting the in-plane stress, and the in-plane stress can be adjusted by laying tape on the skin surface, that is, by adjusting the preload force F applied to the skin after laying the tape. pre Suppress skin deformation; According to the simulation results in step 3, determine the required preload F pre The range of the required tape pretension σ is determined pre The selection range is selected, the applicable tape type is selected within the range, the tape width and the tape laying direction are calculated to determine the tape laying plan, and the tape is laid in the high-risk area according to the tape laying plan; Step 6: Real-time stress monitoring and hierarchical regulation: The skin to be assembled is riveted, and the skin displacement is collected in real time using strain gauges. The real-time pre-tension is calculated based on the equivalent stress principle. Divide the real-time pre-tensioning grading intervals and take corresponding adjustment measures: 1) If Then continue the riveting operation until the skin assembly is completed, where σ yield Represents the yield strength of the skin material; 2) If Then suspend the riveting operation and reselect σ pre The type of tape with a higher value; after removing the laid tape, σ pre The tape with a higher value is laid in the high-risk area according to the original laying plan; the riveting operation is continued to finally complete the skin assembly; 3) If The riveting operation is suspended, and in the high-risk area, the second layer of tape is laid along the direction of the principal stress using the original tape. The direction of the principal stress is obtained by the simulation calculation in step 3; the riveting operation is continued to complete the skin assembly.

3. The method for suppressing aircraft skin assembly deformation based on stress field regulation according to claim 2 is characterized in that: In step 3, the skin stiffness is based on calculate.

4. The method for suppressing aircraft skin assembly deformation based on stress field regulation according to claim 2 is characterized in that: In the step 3, the boundary conditions of the three-dimensional stress-displacement field model include: ① the skin thickness is less than the skin thickness trigger value, ② the rivet spacing is greater than the rivet spacing trigger value, ③ the riveting force range boundary is set according to the skin type, and the rivet forces of various fasteners collected in step 1 must be within the riveting force range boundary; if any of the above conditions is not met, the three-dimensional stress-displacement field model fails.

5. The method for suppressing aircraft skin assembly deformation based on stress field regulation according to claim 2 is characterized in that: In step 4, σ x With N x The relationship is: σ y With N y The relationship is:

6. The method for suppressing aircraft skin assembly deformation based on stress field regulation according to claim 2 is characterized in that: In step 5, the tape width b is calculated using formula (3): Determine the tape laying direction based on the energy functional minimization principle: Where θ is the laying angle, that is, the angle between the tape laying direction and the X-axis, τ xy is the microscopic shear force in the XY plane.

7. The method for suppressing deformation of aircraft skin assembly based on stress field regulation according to claim 2 is characterized in that: In step 5, the tape laying process is: marking the sticking position and direction of the tape on the surface of the skin to be assembled, and laying the tape in the high-risk area by manual laying or sticking equipment.

8. The method for suppressing aircraft skin assembly deformation based on stress field regulation according to claim 2 is characterized in that: In step 6, the strain gauge collects the skin displacement in real time and calculates σ x , σ y and τ xy , and then use formula (5) to calculate the real-time pretension 9. The method for suppressing deformation of aircraft skin assembly based on stress field regulation according to claim 2, characterized in that: In step 6, according to Reselect σ pre Types of tapes with higher values, where ΔT is the pre-tension adjustment and Kp is the proportional coefficient.

10. The method for suppressing aircraft skin assembly deformation based on stress field regulation according to claim 2, characterized in that: In the three-dimensional stress displacement field model, the skin can be simplified as a flat plate with neglected skin curvature, and the riveted state can be simplified as a symmetrical riveted rectangular shape, then N x =N y , that is, the shear forces in the X and Y directions cancel each other out, so N xy =0, that is, no shear stress is generated in the XY plane.

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