Method for calculating assembly deviation of composite material wallboard parts under consideration of interference connection

Abstract

The invention belongs to the technical field of wallboard part assembly deviation analysis, and discloses a composite wallboard part assembly deviation calculation method considering interference connection, and the method comprises the steps: obtaining the initial manufacturing deviation of a part A and a part B, and extracting a super-element stiffness matrix of the parts and an assembly; deterministic positioning and clamping are conducted on the part, and clamping force is calculated; interference connection force is applied for connection, contact calculation is carried out at the assembly connection point, and the interference connection force and contact force are dynamically corrected in an iteration mode until the assembly connection surface reaches contact balance and is located at an ideal position; releasing the constraint of the assembly connecting point and the over-constraint positioning point, and calculating the rebound deformation of the assembly body caused by the corrected acting force; and the initial manufacturing deviation and the springback deformation are synthesized, and the final assembly deviation is calculated. According to the method, the influence of interference connection and contact nonlinearity is considered, and the accuracy of assembly deviation prediction is improved.

Description

Technical Field

[0001] This application belongs to the technical field of assembly deviation analysis of wall panel parts, and specifically relates to a method for calculating assembly deviation of composite material wall panel parts considering interference connections. Background Technology

[0002] Composite material panel components, due to their excellent specific strength and lightweight properties, have become indispensable key structures in modern aerospace manufacturing. These components commonly employ interference fit joining processes to improve the fatigue performance of the joint area. However, due to the anisotropy, low stiffness, and large size inherent in composite materials, they are extremely sensitive to various error sources during assembly. These errors include shape deviations and positioning deviations of the parts themselves, as well as installation deviations of the assembly system. Simultaneously, the clamping forces, contact forces, and springback forces generated during assembly are coupled, further leading to unpredictable deformation of the panel components, ultimately affecting the assembly quality of aircraft components and the overall system.

[0003] Taking typical panel components such as wing box skin and nose fairing as examples, their assembly often employs a flexible tooling system based on the N-2-1 positioning principle. However, due to the combined effects of part manufacturing tolerances, assembly jig errors, and positioning deviations, mating gaps or interference are prone to occur during actual assembly. Although apparent gaps can be eliminated by using fixtures to force assembly, the flexible panel will still spring back and deform due to the rebalancing of internal forces after the assembly force is released.

[0004] Among existing assembly deviation analysis methods, the Method of Influence Coefficients (MIC) provides a basic framework for predicting assembly deviations of flexible components by establishing a linear relationship between component deviations and assembly springback deviations. However, this method does not fully consider the impact of tooling positioning deviations on the assembly process, and its modeling is based on the linear assumption of force and displacement, making it difficult to handle nonlinear contact behaviors that occur during assembly. Furthermore, although some studies have used finite element simulation to virtually analyze the assembly process of flexible parts, covering stages such as positioning, clamping, connection, and release springback, these models typically do not consider the actual contact interactions that occur between parts during the connection process. Especially under interference connection conditions, the local contact and penetration phenomena that may occur between composite material panels cannot be accurately described, leading to discrepancies between the assembly springback deformation analysis results and the actual situation.

[0005] Therefore, due to the failure to effectively handle the nonlinear contact effects generated during the assembly process, the existing technology still has significant limitations in predicting deviations during the assembly process of interference connections in composite panel panels. Summary of the Invention

[0006] To address the inaccuracy of assembly deviation analysis in existing technologies due to neglecting contact nonlinearity, this application aims to provide a method for calculating assembly deviations of composite material panel parts. This method constructs an assembly process analysis model that considers nonlinear contact effects, adjusts the interference connection force and contact force in real time, and characterizes the contact behavior between panels under interference connection conditions. An iterative optimization process is used to gradually correct the contact state, thereby significantly improving the accuracy of assembly deviation prediction.

[0007] To achieve the above technical objectives, this application specifically adopts the following technical solution: In one aspect of this application, a method for calculating assembly deviations of composite panel parts considering interference connections is provided, comprising the following steps: S1. Obtain the initial manufacturing deviations of composite material wall panel parts A and B, and obtain the hyperelement stiffness matrix of parts A, parts B and assembly AB through finite element analysis. S2. Determine the positioning and clamping of parts A and B, and calculate the clamping force at the constraint positioning point; S3. Apply an interference connection force to connect parts A and B, and perform contact calculation at the assembly connection point. Dynamically correct the interference connection force and contact force through iteration until the assembly connection surface reaches contact balance and is located in the ideal assembly position. S4. Release the constraints of the assembly connection points and the over-constraint positioning points, and calculate the springback deformation of the assembly caused by the corrected interference connection force and contact force. S5. Based on the initial manufacturing deviation and the springback deformation, calculate the final assembly deviation of the composite material wall panel parts.

[0008] In one implementation, step S3 involves performing contact calculations at the assembly connection point and dynamically correcting the interference connection force and contact force through an iterative approach, including: Dynamically detect the contact state of the assembly and connection surfaces of composite material wall panels; Calculate the distribution of local contact force based on at least three non-collinear priority contact points on the assembly connection surface; Based on the distance of the interference connection point from the ideal position, the correction amount of the interference connection force is iteratively adjusted until the assembly position requirements are met.

[0009] In one implementation, calculating the distribution of local contact forces includes: For a local area on the assembly connection surface, determine the coordinates of three priority contact points a, b, c and one force-bearing point f; Based on the coordinates of each point, the contact force shared by each contact point is calculated using geometric relationships. , , The force between it and the point of application f The following relationship must be satisfied:

[0010]

[0011]

[0012] in, These represent the lengths of the corresponding line segments.

[0013] In one implementation, the iterative adjustment of the correction amount for the interference connection force includes: According to the Actual offset of the next iteration and target offset The proportion determines the target offset for the nth iteration. The calculation formula is:

[0014] in, This represents the distance between the current interference connection point and the ideal position. Based on the target offset Using the hyperelement stiffness matrix of the assembly Solve for the change in interference connection force .

[0015] In one implementation, the springback deformation of the assembly is calculated in step S4. for:

[0016] in, The rebound force is equal to the vector formed by the corrected interference connection force and the contact force, i.e. ,in, For the corrected interference connection force, The corrected contact force; The hyperelement stiffness matrix is ​​obtained after the interference connection of two composite wall panels A and B, under the condition of releasing the over-constraint positioning device.

[0017] In one implementation, deterministic positioning of parts A and B is performed using positioning based on the 3-2-1 principle, and clamping of parts A and B is performed using over-constraint clamping based on the N-2-1 principle.

[0018] In one implementation, a force sensor is arranged at the clamping point to monitor and control the clamping force, interference connection force, and contact force.

[0019] In one implementation, the final assembly deviation for: ;in, , These represent the manufacturing deviations of composite material panel parts A and B at the constrained positioning points, respectively. This indicates the manufacturing deviation at the assembly connection point of composite panel parts A and B; This represents the springback deformation of the assembly.

[0020] The beneficial effects of this application are as follows: This application effectively characterizes the nonlinear contact behavior of composite panel components during interference connection by introducing a dynamic detection and iterative correction mechanism for the contact state. The method established in this application establishes a coupled correction model of interference connection force and contact force, accurately describing the force flow transmission path at the assembly connection surface and solving the technical problem that traditional linear models cannot accurately predict the stress distribution in the contact area. By constructing the force-displacement response relationship throughout the assembly process, it achieves full-process deviation evolution tracking from positioning and clamping, interference connection to release and springback, significantly improving the accuracy and reliability of assembly deviation prediction. This method provides effective theoretical basis and technical support for the precision assembly of aircraft composite panel components. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the geometric model of the contact force distribution in the local contact area of ​​this application; Figure 2 This is a schematic diagram of the superposition of contact forces at the common point of adjacent contact areas in this application; Figure 3 This is a schematic diagram of the ideal situation after the interference connection of composite material wall panels A and B in this application; Figure 4 This is a schematic diagram of the flexible positioning tooling structure according to an embodiment of this application; Figure 5 This is a simplified schematic diagram of the composite material wall panel, clamping plate and other components according to an embodiment of this application; Figure 6 This is a flowchart of the method for calculating assembly deviations of composite material wall panel parts under interference connection in an embodiment of this application; In the diagram: 1. Composite board A, 2. Composite board B, 3. Threaded column, 4. Clamping plate, 5. Three-coordinate fixture base plate, 6. Top rod, 7. Force sensor. Detailed Implementation

[0022] The technical solution of this application will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are only some embodiments of this application, not all embodiments, and are only used to illustrate this application, and should not be regarded as limiting the scope of this application. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] The purpose of this application is to establish an assembly deviation calculation model that can accurately reflect the mechanical behavior of composite panel panels during interference connection. Traditional methods, based on linear elasticity assumptions, fail to adequately consider the nonlinear mechanical response caused by changes in contact state during assembly. Therefore, this application introduces a dynamic detection and iterative correction mechanism for contact state, decomposing the assembly process into four key stages: positioning and clamping, interference connection, contact balancing, and release / springback. In the interference connection stage, a local mechanical model based on the three-point contact force distribution principle is established by real-time monitoring of the contact state of the connection surfaces, and an iterative algorithm is used to dynamically correct the interference connection force. This method, by constructing the coupling relationship between interference connection force, contact force, and assembly deviation, achieves an accurate description of the nonlinear contact effect during composite panel assembly. Finally, the corrected assembly force is converted into springback deformation using a hyperelement stiffness matrix, and the assembly deviation is predicted in conjunction with the initial manufacturing deviation. This effectively solves the problem of insufficient accuracy in analyzing interference connection assembly using traditional linear models.

[0024] In one specific embodiment, a method for calculating assembly deviations of composite panel parts considering interference connections is provided, comprising the following steps: S1. Obtain the initial manufacturing deviations of composite material panel parts A and B. , , ;in , These represent the manufacturing deviations of composite material panel parts A and B at the constrained positioning points, respectively. This indicates the manufacturing deviation at the assembly connection point of composite panel parts A and B.

[0025] Over-constraint locating points refer to points used for clamping and positioning in addition to the basic 3-2-1 locating points during assembly. These points may introduce positional or shape errors. Assembly connection points refer to the areas where parts A and B are connected by interference connections (such as riveting or high-strength bolts). Manufacturing deviations at these points can affect the connection quality.

[0026] In some embodiments, the initial manufacturing deviation can be obtained through actual measurement or simulation analysis. In actual measurement, a coordinate measuring machine is used to scan parts A and B, collecting actual coordinate data for constrained positioning points and assembly connection points, and comparing it with the theoretical coordinates in the ideal CAD model to calculate the deviation value. , , Deviation values ​​are typically represented as vectors, including the positional errors of points in three-dimensional space. In simulation analysis, finite element method (FEM) software can be used to predict the deviation distribution based on the manufacturing process parameters of the part, thereby extracting the deviation values ​​of key points.

[0027] S2. Extract the hyperelement stiffness matrix of composite panel parts using finite element analysis software. , , The hyperelement stiffness matrix and Let A and B, composite panel parts A and B, be represented by hyperelement stiffness matrices with deterministic positioning as boundary conditions and assembly connection points and over-constrained positioning points as key measuring points, respectively. This indicates that the composite material panels A and B are obtained as an assembly after assembly and connection, with 3-2-1 positioning, over-constraint positioning as boundary conditions, and the assembly connection point as the key measuring point of the super-element stiffness matrix.

[0028] The finite element analysis software used is either ABAQUS or ANSYS.

[0029] In some embodiments, for part A, deterministic positioning boundary conditions are set in the finite element model, i.e., based on the 3-2-1 positioning principle, restricting the six degrees of freedom of the part in space to ensure that the model is in a stable constrained state. Key measurement points include assembly connection points and over-constrained positioning points. Assembly connection points are the locations where part A and part B are connected by interference connections (such as riveting or high-strength bolts), while over-constrained positioning points are additional points used for clamping and control in addition to the basic positioning points. In the software, a unit load or displacement is applied to the key measurement points, and the corresponding response is calculated through static analysis, thereby deriving the reduced stiffness matrix, i.e., the hyperelement stiffness matrix. Similarly, perform the same operation on part B to extract the hyperelement stiffness matrix. Its boundary conditions and key measurement points are defined in the same way as those of part A.

[0030] In some embodiments, the hyperelement stiffness matrix after assembly and connection This represents the overall stiffness of the assembly formed after parts A and B are connected by interference. In the finite element model, parts A and B are assembled as a single unit, and boundary conditions are set as 3-2-1 positioning and over-constraint positioning. 3-2-1 positioning ensures the basic constraints of the assembly in space, while the over-constraint positioning points serve as additional constraint points, simulating the clamping action in actual tooling. Key measuring points are concentrated at the assembly connection points, i.e., the parts where parts A and B are connected. Through finite element analysis, the stiffness response of the assembly at the key measuring points is calculated, thereby extracting the hyperelement stiffness matrix. .

[0031] S3. Determine the location of composite material panels A and B at point... and Perform 3-2-1 positioning for composite panel parts A and B respectively; at the clamping point and Apply additional clamping force to perform N-2-1 positioning of the parts and reduce deformation during the assembly process.

[0032] Specifically, deterministic positioning follows the 3-2-1 positioning principle to restrict all six degrees of freedom of the part in space. For part A, three non-collinear positioning points are selected, denoted as... A 1. A 2. A 3. Point A 1. Restrict the translation of the part along the Z-axis and its rotation about the X and Y axes; point A 2. Restrict the translation of the part along the Y-axis and its rotation about the Z-axis; point A 3. Restrict the translation of the part along the X-axis. Similarly, for part B, select three corresponding positioning points, denoted as... B 1. B 2. B 3. And apply the same constraint principle. Through this positioning method, part A and part B obtain a unique and definite position in space.

[0033] To further enhance positioning stability and reduce deformation that may be caused by the flexibility of the parts themselves and assembly forces, over-constraint positioning, i.e., N-2-1 positioning, was implemented. In addition to the basic positioning points, several clamping points were selected and clamping forces were applied. For part A, a set of clamping points was selected, denoted as... , , For part B, select a corresponding set of clamping points, denoted as... , , By means of actuators on the tooling, such as hydraulic or pneumatic push rods, clamping forces perpendicular to the locating surface are applied to the part at these clamping points. These additional clamping forces firmly press the part against the locating tooling, effectively suppressing elastic deformation of the part caused by its own weight, internal forces generated during connection operations, or contact forces.

[0034] S4. Calculate the clamping force at the constrained positioning point.

[0035] After completing the N-2-1 positioning in step S3, physical clamping is applied to the over-constraint positioning points of composite panel parts A and B. This clamping action manifests as clamping forces. For part A, the resultant clamping force at the over-constraint positioning point is denoted as... Similarly, for part B, the resultant clamping force at the constraint positioning point is denoted as... .

[0036] Based on the principles of linear elasticity and the influence coefficient method, there is a linear relationship between these clamping forces and the displacement response of the parts at the corresponding points. This relationship is characterized by the hyperelement stiffness matrix obtained in step S2. Specifically, the clamping force of part A at the constraint positioning point... , equal to the hyperelement stiffness matrix of part A The displacement vector generated by clamping at the constraint positioning point is different from that of the other two points. The product of . Its mathematical relationship is expressed as:

[0037] Similarly, the clamping force of part B at the constraint positioning point , equal to the hyperelement stiffness matrix of part B The displacement vector generated by clamping at the constraint positioning point is different from that of the other two points. The product of . Its mathematical relationship is expressed as:

[0038] Wherein, displacement vector and It contains displacement component information of each constrained positioning point in three spatial directions.

[0039] Understandably, these over-constrained clamping points will be released after the final assembly is formed, i.e., these additional clamping constraints will be removed. After the clamping force is released, due to the change in the internal stress state of the assembly and the springback effect, the force originally borne by the over-constrained points will be redistributed. The force remaining or rebalanced at the original over-constrained points after release is denoted as... and .

[0040] S5. After the composite material wall panel parts are positioned and clamped, parts A and B are connected by an interference connection. During the application of the positioning clamping force and the interference connection force, the interference connection force at the assembly connection point is: .

[0041] After composite panel parts A and B are stably fixed to the tooling via positioning in step S3 (3-2-1) and over-constraint positioning (N-2-1), an interference connection is made. This interference connection is achieved through riveting or the use of high-strength bolts, creating an interference fit between the connecting hole and the fastener, thereby generating interference stress in the connection point area.

[0042] During this interference connection process, a corresponding interference connection force will be generated at the assembly connection point. This interference connection force is a vector, denoted as . It consists of two components: the force acting on the assembly connection point of part A. and the force acting on the assembly connection point of part B. Therefore, the interference connection force vector is expressed as: .

[0043] From the perspective of force composition, the total interference connection force acting at the assembly connection point These are the component forces acting on parts A and B respectively. and The vector sum of . Their relationship can be expressed as:

[0044] This interference connection force It is generated under the combined action of the positioning clamping force and the interference connection force, which causes the two parts to overcome manufacturing deviations, undergo local deformation, and finally achieve contact and connection at the assembly connection point.

[0045] S6. After the positioning, clamping and interference connection force application of the above steps, when the assembly connection point of composite material wall panel part A and part B is in the ideal matching position, the fastening operation is used to permanently connect the two parts into a unified assembly.

[0046] In some embodiments, the fastening operation may be performed using riveting or high-strength bolts, depending on process requirements. During operation, at pre-prepared assembly connection points, specialized riveting equipment or torque wrenches are used to upset the rivets or tighten the bolts to a predetermined torque. This creates a predetermined interference fit between the fastener and the connecting hole on the part, thereby establishing a secure mechanical connection between the parts.

[0047] S7. After the assembly point reaches the ideal position, perform fine calculation and iterative correction of the contact state.

[0048] After the assembly connection point of composite panel A and B theoretically reaches the ideal assembly position, the contact state between the assembly connection surfaces of the two parts is calculated. Initially, the contact force is assumed to be... In the actual physical process, panels A and B will experience contact forces. The slight positional change caused by the action of the assembly connection point deviates from the ideal assembly position.

[0049] To accurately simulate this process, an iterative approach is used to measure the interference connection force determined in step S5. Make corrections. The corrected interference connection force is denoted as... Its value is the initial interference connection force. With a correction amount sum: .

[0050] To achieve contact balance at the assembly connection surfaces, at least three non-collinear contact points are required to define a contact plane. Furthermore, differences in the specific locations of the stress points on the contact surface will cause variations in the actual distribution of contact points.

[0051] like Figure 1 As shown, assume that in a local area of ​​the assembly connection surface, there are three points that preferentially make contact, with coordinates as follows: , , Meanwhile, the coordinates of the force-bearing points in this local area are... .

[0052] Based on mathematical geometry theory, the equations for the following six lines can be established: The equation of the line ab passing through points a and b is:

[0053] The equation of the line bc passing through points b and c is:

[0054] The equation of the line ca passing through points c and a is:

[0055] Passing through point a and the point of force application The equation of the line af is:

[0056] Passing through point b and the point of force application The equation of the line bf is:

[0057] Passing through point c and the point of force application The equation of the line cf is:

[0058] These six lines intersect each other, with lines af, bf, and cf intersecting the three sides of triangle ABC at three points, denoted as . The specific coordinates of these intersection points can be determined by solving the corresponding equations of the lines.

[0059] Based on the above geometric relationships, the stress points are calculated. The magnitude of the force at point a is distributed to the three priority contact points a, b, and c. The contact force shared by each point is calculated as follows:

[0060]

[0061]

[0062] in, These represent the lengths between the corresponding line segments. In the calculation, the slight unevenness caused by the actual contact surfaces a, b, and c, which may exist at points, is ignored.

[0063] After the contact force calculation for a local element is completed, the forces transmitted between adjacent elements through common points must also be considered. For example... Figure 2 As shown, for two adjacent local regions, the contact force at their common point, for example, point... It is the sum of the contact forces from its various adjacent regions. Point d will experience a separate contact force calculated in a similar way to that of its surrounding region. At this point, the originally calculated contact force between points a and b will change due to the transmission of forces between adjacent regions. The changed contact force is:

[0064]

[0065] in, and The total contact force superimposed after considering the influence of adjacent areas; and It is the contact force component from the adjacent contact area at the corresponding point.

[0066] For the entire composite panel, by dynamically adjusting the contact force and position coordinates of all nodes on the assembly connection surface, and through multiple iterative solutions, a stable contact equilibrium position between the panels is finally obtained. The contact force between the panels determined after reaching the equilibrium state will participate in the subsequent further correction of the interference connection force and the calculation of the final springback force of the assembly.

[0067] S8. The interference connection force after correction in step S7 If the assembly connection point between composite panel A and panel B still cannot achieve the ideal fit, the contact force is recalculated and updated. At this point, the updated contact force... Equal to the contact force obtained in the previous calculation Add a change in contact force ,Right now .

[0068] Meanwhile, changes in the interference connection force and contact force are transmitted through the structure of the parts, affecting the stress state at the positioning and clamping points. Therefore, the forces acting on the positioning and clamping points also need to be updated accordingly. The updated positioning and clamping forces... equal to the initial clamping force Add a clamping force change ,Right now The change in clamping force With the corrected interference connection force and the updated contact force The correlation is expressed as follows: , where D is a response coefficient matrix, which characterizes the sensitivity of the force on the positioning clamping point to the force at the interference connection point and the contact point.

[0069] Although the composite panel theoretically reaches the ideal assembly position under the action of interference connection force, the contact calculation analysis in step S7 shows that the parts will deviate in position due to contact interaction. After the contact force is included in the assembly deviation calculation, the actual offset of the assembly connection point of the composite panel is inconsistent with the predicted value under purely theoretical conditions. Iterative solution is required based on the equilibrium position obtained after contact calculation.

[0070] To facilitate efficient iterative calculations, we make the following assumption: in each iteration, the offset of the assembly connection point is controlled within a very small range, and this offset is less than the expected offset under ideal conditions. Within this small range of variation, the influence of the contact state of the assembly connection surface on the position can be considered approximately linear. Based on this linear assumption, the target offset for each iteration can be determined according to the proportional relationship of the offset from the previous iteration.

[0071] Let the first In the next iteration, the actual offset of the assembly connection point is: The target offset set for this iteration is In the first In the next iteration, the actual offset is The target offset is ,but:

[0072] If the distance between the current measurement or calculation and the interference connection point's deviation from its ideal assembly position is... Then this iteration (the ) The target offset to be set (time) It should meet the following requirements:

[0073] Based on the target offset set for the interference connection point, the change in the required interference connection force is calculated. The solution process utilizes the assembly hyperelement stiffness matrix obtained in step S2. Establish the following relationship:

[0074] in, It is the contact force exerted on key points on the contact surface of the composite material wall panel. and These are the displacement vectors generated by the interference connection point and the contact point during this iteration. Using this equation, the magnitude of the force requiring correction can be calculated based on the target displacement, thus completing one iteration of correction. This process is repeated until the assembly accuracy requirements are met.

[0075] S9. After completing the interference connection and achieving contact balance, release the constraints during the assembly process and determine the resulting springback force.

[0076] Once composite panel A and B form a complete assembly through interference connection, and the contact state of the assembly connection surfaces reaches equilibrium through iterative calculation, the external constraints applied to the assembly are released. Specifically, all clamping and supporting forces previously applied for forced positioning at the assembly connection points and over-constraint clamping points are released.

[0077] As the elastic strain energy stored inside the assembly is released, the entire assembly will undergo a certain degree of shape change, which is called springback. Springback occurs because during the assembly process, the parts undergo elastic deformation under the action of various assembly forces (including positioning clamping forces, interference connection forces, and contact forces). When the external forces are removed, the parts tend to return to their initial state.

[0078] The resultant force that causes the assembly to spring back is called the springback force, denoted as . The rebound force is numerically approximately equal to the sum of the reaction forces of the main forces applied to the assembly during the assembly process. These main forces include the interference connection forces determined in the final corrections of steps S7 and S8. And the contact force calculated in step S7 that acts on the contact surface after contact equilibrium is reached. Therefore, rebound force This can be represented as a combination of these two force vectors, i.e.: .

[0079] S10. Calculate the springback deformation of the assembly after the constraints are released, i.e., the final shape deviation.

[0080] The amount of springback deformation is denoted as This characterizes the final shape deviation of the composite panel in the free state.

[0081] The calculation is based on the constitutive relationship between force and deformation in linear elasticity. Specifically, the amount of springback deformation... With rebound force The relationship is expressed through a hyperelement stiffness matrix. It is constructed using the inverse matrix. Its mathematical expression is:

[0082] Among them, the hyperelement stiffness matrix The stiffness matrix is ​​obtained after composite panels A and B are connected by interference to form a complete assembly, under the condition that all over-constrained positioning devices are released. "Release of over-constrained positioning devices" means that, in the finite element model or in a physical sense, all additional clamping point constraints applied in step S3 that exceed the 3-2-1 positioning principle are removed, so that the assembly maintains only a basic statically determinate support state. The hyperelement stiffness matrix is ​​extracted or calculated under these boundary conditions. It accurately reflects the overall rigidity characteristics of the assembly in a free state.

[0083] The above calculations yielded the following results. This refers to the springback deviation exhibited by the composite panel assembly after considering a series of complex processes such as interference connection, contact force, and constraint release.

[0084] S11. Based on the cumulative deformation from all deviation sources, calculate the assembly deviation of the composite material wall panel parts, i.e. .

[0085] The assembly deviation calculation method proposed in this application is based on the influence coefficient method. This method is based on the assumption that composite materials exhibit linear elastic behavior during the elastic deformation stage. The analysis specifically considers the influence of contact forces between parts on the overall deformation during assembly.

[0086] Finite element analysis (FEM) can be used to pre-calculate the quantitative relationship between the deviation of the panel shape and the applied clamping force. In subsequent analyses, these clamping forces are used as known input conditions to predict the deformation of the panel components. Specifically, by calculating the deformation at key feature points between the contacting surfaces of the composite panel, the final deviation of the assembly after assembly springback can be determined. By setting different load combinations, deformation results under various load conditions can be obtained.

[0087] The mathematical principles of this method can be explained from the following two aspects: First, in steps S5 and S10, the gap values ​​measured or calculated at the corresponding key points of the composite material wall panel are used as the input deviation for analysis. Based on this, a linear mathematical relationship is established between the initial deviations generated by various deviation sources and the final assembly deviations. Specifically, the influence coefficient method is applied to construct a linear relationship model between the physical gap at the interference connection point and the springback amount of the assembly:

[0088] in, [S] represents the springback of all key feature points on the composite board after interference bonding, and [S] represents the sensitivity matrix. This indicates the clearance value at the assembly connection point between composite material panel part A and part B.

[0089] Secondly, in steps S7 and S8, the analysis method fully considers the role of contact forces throughout the assembly process. An incremental method is used to solve the contact problem. This is because when the assembly connection surfaces come into contact, their physical constraints are usually in inequality form, and the actual contact state and contact range of the composite panel assembly connection area are unknown before analysis.

[0090] Considering the characteristics of contact force in assembly deviation calculations, the solution is to employ an iterative process requiring repeated corrections. The main steps of this process are: first, based on the physical conditions of contact constraints, a preliminary contact assessment is made of the assembly connection surfaces; then, the corresponding kinematic conditions on the assembly connection surfaces are used as the basis for each iterative calculation; this process is repeated, gradually reducing and ultimately eliminating the mutual intrusion effect caused by contact, until the entire system reaches a contact state of force and displacement equilibrium. In this equilibrium state, the interference connection points of the composite material wall panels also simultaneously reach the ideal connection positions. Figure 3 The diagram shows the ideal connection state achieved by composite panel A and B after interference connection.

[0091] Example like Figure 4 and Figure 5As shown, the flexible positioning fixture mainly consists of a threaded column 3, a clamping plate 4, a three-coordinate fixture base plate 5, and a push rod 6. A force sensor 7 is arranged between the push rod and the plates to connect composite plates A1, 2 and B2.

[0092] like Figure 6 The diagram shown is a flowchart of a method for calculating assembly deviations of composite panel parts considering interference connections.

[0093] This example uses two composite panels, a clamping plate, four columns, and a top rod to illustrate in detail the assembly deviation calculation method provided by this invention, including the following steps: S1: The prepared fixture is the base plate of the three-coordinate clamping fixture. Install the threaded column and top column onto the fixture, and place the clamping plate and composite material wall panel in the predetermined positions. It should be noted that a wall panel part with a high surface profile was selected and regarded as the ideal model of the wall panel part in the assembly process experiment. The hyperelement stiffness matrix of composite plates A and B was obtained by substituting the model into the finite element analysis software. ; S2: Positioning of composite material wall panel: The composite panel is placed on the base plate of the three-coordinate fixture. The outer surface of the composite panel is the main positioning surface. Based on the six-point positioning principle, the composite panel is positioned deterministically by the combination of slot pins set on the clamping plate. The composite material wall panel is over-constrained and positioned by the top rod.

[0094] S3: Clamping of composite panel: Force sensors are arranged between the top rod and the plate. By controlling the load applied to the composite panel, corresponding clamping forces are applied to the deterministic positioning point and the over-constraint positioning point of the composite panel to realize the clamping process of composite panels A and B. S4: Composite panels A and B come into contact. A force sensor placed between the top rod and the composite panel controls the contact force at key points on the contact surface, so that the panel parts can reach the ideal assembly connection position after interference connection. S5: Interference connection is made between composite panels A and B. The contact force between the push rod and the panel is monitored and controlled by a force sensor. Different loads are applied, and the interference connection force needs to be corrected based on the changes in contact force. The composite panel will deform. The gap value at the key mating points of the two composite panels is measured. To determine whether composite panels A and B have reached the ideal contact equilibrium position: the deformations of the key points at the mating surfaces of composite panels A and B in the normal direction are as follows: and The gap value at the mating point is obtained by subtracting the normal deformation values ​​of the two composite wall panels: = - ;when At this time, the assembly contact surfaces reach the ideal contact balance position; This method, based on the influence coefficient method and starting from the linear elastic assumption, considers the deformation influence caused by contact forces during the assembly of composite panel. It pre-determines the mapping relationship between panel shape deviation and clamping force using the finite element method, and uses the clamping force as the input source for deformation analysis of the panel component. The deformation at key feature points between the contact surfaces of the composite panel is calculated to represent the deviation of the assembly after springback. Furthermore, based on different load combinations, the deformation under different loads is obtained. Its mathematical mechanism is as follows: In step S5, the gap values ​​of the composite material wall panel at the corresponding key points are used as input deviations to establish a linear relationship between the deviation source deviation and the assembly deviation. The influence coefficient method is then used to establish a linear relationship between the gap and the springback at the interference connection point.

[0095] In the formula, [S] represents the springback of all key feature points on the composite board after interference bonding, and [S] represents the sensitivity matrix.

[0096] S6: Release the force at the assembly connection points and over-constraint clamping points. The assembly will spring back to a certain extent. The force sensor can detect the force at each key point, and the springback force on the assembly at this time. Approximately equal to the reaction force of the interference connection force and the over-constraint positioning clamping force ; S7: Calculate the springback deformation of the assembly. Based on a force sensor, the springback force can be obtained. The relationship between the springback deformation and the corresponding springback force can be expressed as follows: The final springback deviation of the composite wall panel is obtained. ; It is the hyperelement stiffness matrix obtained after the two composite plates A and B are connected by interference and the constraint positioning device is released; S8: Apply different loads based on manufacturing errors at key points in the contact area. At this time, the applied load force is equal to the rebound force of each contact point when released. The rebound deformation at each key point of the composite material wall panel is calculated, the deformation of the key points of the composite material wall panel under different loads is obtained, the distribution function of the rebound deformation of the composite material wall panel is fitted, and the overall rebound deformation of the composite material wall panel is obtained. S9: Based on the cumulative deformation from all deviation sources, calculate the assembly deviation of the composite material panel parts, i.e. .

[0097] Although the embodiments of this application have been described above in conjunction with the accompanying drawings, this application is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, not restrictive. Those skilled in the art can make many other forms based on the guidance of this specification and without departing from the scope of protection of the claims of this application, and these are all within the scope of protection of this application.

Claims

1. A method for calculating assembly deviations of composite material panel parts considering interference connections, characterized in that, Includes the following steps: S1. Obtain the initial manufacturing deviations of composite material wall panel parts A and B, and obtain the hyperelement stiffness matrix of parts A, parts B and assembly AB through finite element analysis. S2. Determine the positioning and clamping of parts A and B, and calculate the clamping force at the constraint positioning point; S3. Apply an interference connection force to connect parts A and B, and perform contact calculation at the assembly connection point. Dynamically correct the interference connection force and contact force through iteration until the assembly connection surface reaches contact balance and is located in the ideal assembly position. S4. Release the constraints of the assembly connection points and the over-constraint positioning points, and calculate the springback deformation of the assembly caused by the corrected interference connection force and contact force. S5. Based on the initial manufacturing deviation and the springback deformation, calculate the final assembly deviation of the composite material wall panel parts.

2. The assembly deviation calculation method according to claim 1, characterized in that, Step S3 involves performing contact calculations at the assembly connection points, and dynamically correcting the interference connection force and contact force through an iterative approach, including: Dynamically detect the contact state of the assembly and connection surfaces of composite material wall panels; Calculate the distribution of local contact force based on at least three non-collinear priority contact points on the assembly connection surface; Based on the distance of the interference connection point from the ideal position, the correction amount of the interference connection force is iteratively adjusted until the assembly position requirements are met.

3. The assembly deviation calculation method according to claim 2, characterized in that, The calculation of the distribution of local contact force includes: For a local area on the assembly connection surface, determine the coordinates of three priority contact points a, b, c and one force-bearing point f; Based on the coordinates of each point, the contact force shared by each contact point is calculated using geometric relationships. , , The force between it and the point of application f The following relationship must be satisfied: in, These represent the lengths of the corresponding line segments.

4. The assembly deviation calculation method according to claim 2, characterized in that, The correction amount for the iterative adjustment of the interference connection force includes: According to the Actual offset of the next iteration and target offset The proportion determines the target offset for the nth iteration. The calculation formula is: in, This represents the distance between the current interference connection point and the ideal position. Based on the target offset Using the hyperelement stiffness matrix of the assembly Solve for the change in interference connection force .

5. The assembly deviation calculation method according to claim 1, characterized in that, In step S4, the springback deformation of the assembly is calculated. for: in, The rebound force is equal to the vector formed by the corrected interference connection force and the contact force, i.e. ,in, For the corrected interference connection force, The corrected contact force; The hyperelement stiffness matrix is ​​obtained after the interference connection of two composite wall panels A and B, under the condition of releasing the over-constraint positioning device.

6. The assembly deviation calculation method according to claim 1, characterized in that, Deterministic positioning of parts A and B is performed using positioning based on the 3-2-1 principle, while clamping of parts A and B is performed using over-constraint clamping based on the N-2-1 principle.

7. The assembly deviation calculation method according to claim 1, characterized in that, A powerful sensor is placed at the clamping point to monitor and control the clamping force, interference connection force, and contact force.

8. The assembly deviation calculation method according to claim 1, characterized in that, The final assembly deviation for: ;in, , These represent the manufacturing deviations of composite material panel parts A and B at the constrained positioning points, respectively. This indicates the manufacturing deviation at the assembly connection point of composite panel parts A and B; This represents the springback deformation of the assembly.

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