Aviation thin-wall curved surface structure assembly coordination error accumulation transmission calculation and evaluation method and system

Abstract

The invention provides an aviation thin-wall curved surface structure assembly coordination error accumulation transfer calculation and evaluation method and system.The method comprises the steps that firstly, an assembly mechanical state and measured data are fused, multi-source errors are analyzed and represented through the coupling effect of multiple physical fields, and an assembly error transfer path is constructed; according to the structural characteristics of the aviation thin-wall structure parts, an error transfer value between part assembly is quantitatively represented, an assembly deviation transfer calculation matrix is updated in combination with the real-time mechanical state of the aviation thin-wall structure, and accurate calculation of the assembly error of the thin-wall parts is achieved; thirdly, quantitatively evaluating the composite thin-wall surface assembly appearance error cumulative effect by combining the actually measured force and position data of the key feature points; and finally, optimizing the assembly process based on the accurate calculation and quantitative evaluation result of the assembly error. According to the method, the problems of high uncertainty of assembly precision transmission, forced shape correction after the event and the like caused by a traditional assembly process coordination method mainly based on geometric quantity control can be solved.

Description

Technical field

[0001] The present invention relates to the technical field of quality control of aviation thin-walled curved surface structure assembly engineering, and in particular to a method and system for calculating and evaluating the cumulative transfer of coordination errors in aviation thin-walled curved surface structure assembly. [Background Technology]

[0002] In the aerospace industry, the coordination and error propagation of assembly errors is a key constraint on overall production progress and quality. This is particularly true for next-generation aircraft wing components, which demand stringent operational requirements such as high stealth, high reliability, and high maneuverability. This requires significantly higher standards for assembly error coordination accuracy compared to previous models. However, due to the complex structure of aircraft, which involves numerous thin-walled, curved components, traditional assembly control methods, typically based on assembly dimension chain analysis, fail to fully consider the interactions between components and complex assembly scenarios, including changes in component stress states and geometric shape. This makes it difficult to accurately predict and optimize errors during the assembly process. Furthermore, thin-walled composite components are subject to large manufacturing errors and are prone to elastic deformation. Consequently, during the manufacturing process, due to the combined effects of component manufacturing error fields, tooling positioning error fields, positioning and clamping load fields, connection load fields, and assembly temperature fields, thin-walled components can experience deviations due to process and environmental factors, leading to undesirable geometric and deformation deviations. The combined effects of these deviation factors make thin-walled composite components highly susceptible to deformation during assembly, impacting the final overall assembly quality and, in turn, negatively impacting the overall mechanical performance of the aircraft. In addition, in the aviation multi-station assembly scenario, the force and deformation transmission between composite thin-walled parts in different assembly sequences are also completely different, which further makes the dimensional deviation of the overall structure after the accumulation of aircraft assembly errors show extremely strong uncertainty, and the assembly quality is extremely difficult to control.

[0003] In order to reduce and control product deviations, lower rework rates, and improve assembly success rates during aircraft assembly, companies not only need to adopt advanced automated equipment such as automatic drilling and riveting, laser measuring instruments, etc. to improve production efficiency, reduce manufacturing costs, and improve component accuracy, but also need to find more scientific assembly process methods. In the assembly process stage, the generation and transmission process of assembly errors should be clarified and a cumulative transmission method for assembly errors should be established to predict and improve assembly errors at the assembly site.

[0004] Due to the complexity of aircraft structures, the difficulty in controlling the accumulation of coordinated dimensional errors, and the inadequacy of coordinated assembly process control, existing methods for predicting assembly error accumulation based on theoretical design models, as well as corresponding assembly process planning and tolerance allocation control, are particularly challenging to control key quality indicators such as shape, clearance, and step difference during actual manufacturing / assembly. In practical engineering, existing thin-walled structure assembly processes rely primarily on the designers' years of experience and repeated manual adjustments during on-site assembly. This not only significantly increases assembly costs, but also prolongs assembly time and reduces product quality, severely impacting the assembly efficiency of aerospace products. Therefore, to accurately predict the assembly coordination errors of thin-walled curved aerospace structures and effectively evaluate the cumulative error transfer results, it is necessary to overcome the shortcomings of existing technologies. It is necessary to integrate the assembly mechanical conditions involved in the assembly process with measured data to achieve precise prediction and calculation of assembly coordination errors and effectively evaluate the effectiveness of the cumulative results. This can address the problems of large assembly accuracy transfer uncertainty and post-process forced corrections associated with traditional assembly process coordination methods that primarily rely on geometric control.

[0005] Therefore, it is necessary to study a calculation and evaluation method and system for the cumulative transfer of coordination errors in the assembly of aviation thin-walled curved surface structures to address the shortcomings of existing technologies and to solve or alleviate one or more of the above problems. [Summary of the invention]

[0006] In view of this, the present invention provides a method and system for calculating and evaluating the cumulative transmission of coordinated errors in the assembly of aviation thin-walled curved surface structures. First, by combining the fusion of assembly mechanical states and measured data, the coupling effects of composite thin-walled components in multiple physical fields such as gravity field, manufacturing error field, deformation field, and stress field are analyzed to accurately characterize multi-source errors, construct assembly error transmission paths, and provide a theoretical basis for the calculation of assembly error accumulation; secondly, according to the structural characteristics of aviation thin-walled structure parts, the error transmission values ​​between component assemblies are quantitatively characterized, and the assembly deviation transmission calculation matrix is ​​updated in combination with the real-time mechanical state of aviation thin-walled structures to achieve accurate calculation of thin-walled component assembly errors; thirdly, combined with the measured force and position data of key feature points, the cumulative effect of composite thin-walled surface assembly shape errors is quantitatively evaluated; finally, based on the results of accurate calculation and quantitative evaluation of assembly errors, the assembly process is optimized to achieve rapid and accurate prediction of assembly cumulative transmission errors and effective improvement of assembly quality.

[0007] On the one hand, the present invention provides a method for calculating and evaluating the cumulative transmission of coordination errors in the assembly of aviation thin-walled curved surface structures, which is used to reduce the errors of aviation thin-walled curved surface structures and improve the accuracy of assembly parts. The method first characterizes multi-source errors by analyzing the coupling effects of aviation thin-walled curved surface structures in multiple physical fields, and constructs an assembly error transmission path; secondly, according to the characteristics of the aviation thin-walled curved surface structure and the assembly error transmission path, the error transmission values ​​between the assembly parts are quantitatively characterized, and the assembly deviation transmission calculation matrix is ​​updated in combination with the real-time mechanical state of the aviation thin-walled structure to achieve accurate calculation of assembly errors; thirdly, the measured force and position data of key feature points are combined to quantitatively evaluate the cumulative effect of the assembly shape errors of composite thin-walled surfaces; finally, based on the results of the accurate calculation and quantitative evaluation of assembly errors, the assembly process is optimized;

[0008] According to the above aspects and any possible implementation, an implementation is further provided, wherein the method for calculating and evaluating the cumulative transfer of coordination errors in assembly of thin-walled curved surface structures for aviation comprises the following steps:

[0009] S1: Analyze the multi-physics coupling effect in the assembly process of aviation thin-walled structures, establish a mechanical state model of assembly deviation of aviation thin-walled structures, and characterize the changes in error sources during the assembly process;

[0010] S2: Obtain the measured information of assembly process deformation and component manufacturing errors through the changes in the error sources during the assembly process, establish a flexible mating surface symbol representation matrix, and construct multiple transmission path models between various error sources in aviation thin-walled structures through the flexible mating surface symbol representation matrix;

[0011] S3: Based on the theory of small displacement screws and homogeneous coordinate transformation, and following the multiple transfer path models between various error sources in aviation thin-walled structures, an initial transfer matrix for assembly deviation accumulation calculation is constructed;

[0012] S4: Based on the initial transfer matrix used for assembly deviation accumulation calculation and the multi-physics field coupling deviation value of the assembly process, the deviation transfer factor is dynamically updated and the initial transfer matrix is ​​corrected to generate a deviation transfer matrix that integrates the assembly deformation, accurately calculating and obtaining the assembly coordination error at the key feature points required by the assembly process;

[0013] S5: Obtain the discrete point data of key feature errors on the assembly surface of aviation thin-walled structures through the assembly coordination errors at key feature points in the assembly process requirements, construct a thin plate spline interpolation function, and obtain an interpolation surface that can reflect the true state of error accumulation;

[0014] S6: Using the stability entropy function, a comprehensive evaluation system is established with the assembly error value as the dominant indicator and the local entropy value as the additional indicator. The interpolation surface that can reflect the true state of error accumulation is used to quantitatively evaluate the cumulative numerical value and distribution of the assembly error of the thin-walled curved surface structure under the current transmission path, and the optimal assembly sequence is screened out. If the assembly accuracy requirements are not met, the assembly process and parameters are further optimized and improved.

[0015] According to the above aspects and any possible implementation, an implementation is further provided, wherein S1 specifically includes:

[0016] S11: Based on the assembly accuracy requirements of aviation thin-walled structures in the assembly process, the key features of aviation thin-walled structures are classified to clarify the types of assembly error sources of aviation thin-walled structures. The key features include positioning features, connection features, and measurement features.

[0017] S12: Analyze the coupling effects of gravity, manufacturing error, deformation, and stress fields during the assembly process by analyzing the types of assembly error sources for thin-walled aviation structures. Utilize the super-element stiffness matrix theory in finite element analysis to establish an assembly deviation mechanics model for the positioning, clamping, and release / springback stages of thin-walled aviation structures. This model captures the changing states of key features of different error sources at each assembly stage.

[0018] S13: Based on the small displacement screw theory, the six-degree-of-freedom screw parameters of the variable geometry are described to quantitatively characterize the changes in different types of error sources during the assembly process. The different types of error sources include changes in manufacturing error sources, tooling positioning error sources, and assembly deformation error sources.

[0019] According to the above aspects and any possible implementation, an implementation is further provided, wherein S2 specifically includes:

[0020] S21: Obtain measured information on assembly process deformation and component manufacturing errors through the changes in different types of error sources, and clarify the relationship between actual assembly changes and true geometric fit constraints;

[0021] S22: Using polychromatic set theory, describe the assembly relationship between parts of aerospace thin-walled structures, the types of mating surfaces, and the functional characteristics of constraint directions, obtain the transfer properties and degree-of-freedom constraint states of different types of error sources, and construct a symbolic representation matrix for flexible mating surfaces;

[0022] S23: Define the initial reference components and final precision output components in the aerospace thin-walled structure, and, in combination with assembly positioning and mating priority, construct a flexible mating surface transfer attribute matrix using the flexible mating surface symbol representation matrix results. Then, sequentially conduct an error transfer path search for the flexible aerospace thin-walled structure to obtain multiple transfer paths for each error component.

[0023] S24: Analyze and obtain the error transmission paths of all components in aviation thin-walled structures, and use the deviation values ​​under the multi-physics field coupling effect to identify and screen them, retaining a small number of error transmission paths that meet the assembly accuracy requirements, and using a tree diagram method to construct the error transmission paths between the various error sources in flexible aviation thin-walled structures.

[0024] According to the above aspects and any possible implementation, an implementation is further provided, wherein S3 specifically includes:

[0025] S31: Based on the key features on the mating surfaces of components, the small displacement screw theory is used to convert the position changes of the key features into an error screw model matrix. This is then mapped to the tolerance domain using inequality constraints. An error screw model of typical functional features is constructed to quantitatively describe the positional offset and posture deviation of components during the manufacturing process.

[0026] S32: Using the theory of homogeneous coordinate transformation, based on the changes in manufacturing error sources, tooling positioning error sources, and assembly deformation error sources during the assembly process in S1 and the error transmission paths between the error sources of the flexible aviation thin-walled structure in S2, the spatial posture transmission relationship between the various components of the aviation thin-walled structure is described in matrix form, and the aviation thin-walled structure deviation transfer calculation matrix is ​​constructed as the initial transfer matrix for the assembly deviation accumulation calculation.

[0027] According to the above aspects and any possible implementation, an implementation is further provided, wherein S4 specifically includes:

[0028] S41: Based on the initial transfer matrix used for assembly deviation accumulation calculation in S3, the discrete node coordinates of the mating surfaces of key assembly features after deformation are extracted according to the physical deformation information during the assembly process of the aviation thin-walled structure;

[0029] S42: Based on the node coordinate values, the geometric deviations of the size, shape and position of the mating surfaces of key assembly features are calculated through the spatial position mapping relationship between the ideal surface and the fitted surface, and the error screw model of the fusion deformation factors in the assembly process is obtained;

[0030] S43: An initial geometric deviation transfer calculation matrix is ​​constructed by using an error screw model that integrates deformation factors during the assembly process. A deformation surface compensation mechanism under external loads is introduced to dynamically update and correct the constructed initial geometric deviation transfer calculation matrix. An assembly deviation transfer calculation matrix model that integrates deformation factors and manufacturing errors is established to obtain an assembly deviation transfer calculation matrix that integrates deformation errors.

[0031] S44: Apply error flow theory to construct a deviation transfer model for component assembly processes applicable to multiple assembly steps, calculate the error accumulation value corresponding to the deviation transfer matrix under a specific assembly sequence, and accurately calculate the assembly coordination error between key assembly features in the assembly process requirements.

[0032] According to the above aspects and any possible implementation, an implementation is further provided, wherein S5 specifically includes:

[0033] S51: Obtain discrete point data of key feature errors on the assembly surface of thin-walled aerospace structures through assembly coordination errors at key feature points in assembly process requirements. Apply the mathematical principle of thin-plate spline interpolation function, use the measured force and position data of discrete key feature points on thin-walled curved surface parts, and adopt the thin-plate spline basis function method to obtain the distance matrix from the interpolation point to the known point.

[0034] S52: Construct a block coefficient matrix containing basis function terms and low-order polynomial terms, solve the constrained linear equations to determine the interpolation coefficients, implement the construction and solution of the thin plate spline interpolation function matrix, and reconstruct a three-dimensional surface that can reflect the cumulative state of the panel assembly error;

[0035] S53: Use the interpolation coefficient to calculate the z value of the point to be interpolated, generate the interpolation surface of the thin-walled structure and visualize it, and intuitively present the error distribution law of the surface of the thin-walled curved surface workpiece.

[0036] According to the above aspects and any possible implementation, an implementation is further provided, wherein S6 specifically includes:

[0037] S61: Analyze the evaluation requirements of the cumulative effect of surface assembly errors on thin-walled workpieces and establish the relationship between the distribution uniformity of surface shape errors and the assembly quality of aviation thin-walled structures;

[0038] S62: Based on the stability entropy function and the evaluation process of surface error distribution, a comprehensive evaluation system is established with the assembly error transfer cumulative value as the main evaluation indicator and the convex hull local entropy value as an additional evaluation indicator. Quantitative analysis is carried out on the error distribution law of the fitted curved thin-walled surface workpiece surface to achieve a quantitative assessment of the thin-wall assembly cumulative error and its distribution under the current transfer path;

[0039] S63: sorting multiple assembly error transmission paths based on entropy calculation results corresponding to different assembly sequences, and selecting assembly sequences with higher assembly performance;

[0040] S64: Compare the assembly accuracy values ​​under different assembly sequences. If the assembly requirements are not met, it is necessary to further optimize the process parameters and improve the assembly process from the assembly process level.

[0041] According to the above aspects and any possible implementation, an implementation is further provided, wherein S62 specifically includes:

[0042] S621: Use relative entropy method to make a preliminary evaluation of the surface shape distribution error;

[0043] S622: When the result of the preliminary entropy evaluation indicates that the surface shape error is non-uniformly distributed, searching for a convex hull on the surface shape;

[0044] S623: Based on the searched convex hull, a top plane is constructed, and the maximum shape error of the assembled surface is calculated in combination with the ideal surface;

[0045] S623: Perform local entropy analysis on the convex hull area to obtain the local entropy value of each convex hull;

[0046] S624: Obtain a comprehensive evaluation index of the assembly surface shape distribution error based on the entropy value calculation result.

[0047] As described above and any possible implementation method, an implementation method is further provided, in which the S64 aims to improve the assembly accuracy of thin-walled parts, and is carried out from three solutions: adjusting the assembly sequence, adjusting the positioning scheme, and adjusting the tolerance range. Subsequently, virtual simulation verification is used to achieve a rapid improvement in the assembly accuracy of thin-walled parts.

[0048] According to the above aspects and any possible implementation, a system for calculating and evaluating the cumulative transfer of coordination errors in assembly of thin-walled curved surface structures in aviation is further provided. The system for calculating and evaluating the cumulative transfer of coordination errors in assembly of thin-walled curved surface structures in aviation comprises:

[0049] The error source transfer path model construction module is used to combine the deformation of the assembly process with the measured information of component manufacturing errors to construct the transfer path model between the various error sources of flexible aviation thin-walled structures;

[0050] The error transfer matrix construction and update module is used to characterize the dynamic changes of the transfer factors of each error source during the assembly process, generate the deviation transfer matrix that integrates the assembly deformation, and accurately calculate the assembly coordination error at key feature points;

[0051] The error transfer evaluation and process optimization module is used to construct an interpolation surface of the actual state of assembly error accumulation, and to quantitatively evaluate and optimize the assembly error accumulation and distribution of thin-walled surfaces.

[0052] Compared with the prior art, the present invention can achieve the following technical effects:

[0053] 1) A mechanical deformation analysis model for the assembly process was established, and an assembly error transfer path analysis method considering the effects of multi-physics coupling was proposed. By obtaining the deviation values ​​under the effects of multi-physics coupling, a flexible mating surface symbol matrix was established, and an error transfer path model for flexible aerospace thin-walled structures was constructed. This error transfer path was solved, providing a basis for calculating assembly error accumulation.

[0054] 2) By integrating deformation factors during the assembly process with measured assembly data, a dynamic update mechanism for the assembly deviation transfer calculation matrix that considers assembly deformation is proposed. Physical deformation information during the assembly process is analyzed and quantified as deviation transfer factors, generating a deviation transfer calculation matrix that incorporates assembly deformation. By acquiring multi-physical field coupling deviation values ​​in real time, the deviation transfer factors are dynamically updated and the transfer calculation matrix is ​​corrected to achieve accurate calculation of assembly errors.

[0055] 3) By converting discrete point data on key feature errors in the assembly surfaces of multiple thin-walled aerospace structures into surface variation data, a quantitative evaluation method for the assembly shape errors of thin-walled composite materials is proposed. Combining this data with discrete point data on key feature errors in the assembly surfaces of thin-walled aerospace structures, an interpolation surface that reflects the state of error accumulation is constructed based on the theory of thin-plate spline interpolation functions. Using the stability entropy function, a comprehensive evaluation system is established, with assembly error as the dominant indicator and local entropy as an additional indicator. This quantitative evaluation of the accumulated errors on thin-walled surfaces can serve as a basis for optimizing assembly processes and process parameters.

[0056] Of course, any product implementing the present invention does not necessarily need to achieve all of the above-mentioned technical effects at the same time.

Brief Description of the Drawings

[0057] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0058] Figure 1 This is a step diagram of the calculation and evaluation technology for the coordination error accumulation transfer of the assembly of the aviation thin-walled curved surface structure of the present invention;

[0059] Figure 2 This is a flow chart of the assembly coordination error cumulative transfer calculation and evaluation technology provided by one embodiment of the present invention;

[0060] Figure 3 It is the symbol matrix of the flexible mating surface of the aviation thin-walled structure in the present invention and its information expression;

[0061] Figure 4This is a description of the structure and adjustable functions of the typical box segment assembly tooling of the present invention;

[0062] Figure 5 This is a diagram of the overall assembly structure of a composite material wing box provided by one embodiment of the present invention;

[0063] Figure 6 It is the symbol matrix of the flexible mating surface of the wing box aviation thin-wall structure of the present invention;

[0064] Figure 7 This is the error transmission path corresponding to the assembly step difference between the wing box upper panel skins P7 and P8 of the present invention;

[0065] Figure 8 This is the actual surface assembly state of the upper wall panel skin under the four assembly paths of the wing box product of the present invention;

[0066] Figure 9 is a comprehensive evaluation result curve of the upper wall panel skin under four assembly paths of the wing box product of the present invention;

[0067] Figure 10 These are the simulation results before and after the single adjustment of the wing box upper panel assembly deviation of the present invention;

[0068] Figure 11 These are the simulation results before and after the comprehensive adjustment of the assembly deviation of the wing box upper wall panel of the present invention. [Specific implementation method]

[0069] In order to better understand the technical solution of the present invention, the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0070] It should be understood that the embodiments described are only a portion of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0071] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "an", "the" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0072] The present invention provides a method for calculating and evaluating the cumulative transmission of coordination errors in the assembly of an aviation thin-walled curved surface structure. The method comprises the following steps:

[0073] S1: Analyze the multi-physics coupling effect in the assembly process of aviation thin-walled structures, establish a mechanical state model of assembly deviation of aviation thin-walled structures, and characterize the changes in error sources during the assembly process;

[0074] S2: Obtain the measured information of assembly process deformation and component manufacturing errors through the changes in the error sources during the assembly process, establish a flexible mating surface symbol representation matrix, and construct multiple transmission path models between various error sources in aviation thin-walled structures through the flexible mating surface symbol representation matrix;

[0075] S3: Based on the theory of small displacement screws and homogeneous coordinate transformation, and following the multiple transfer path models between various error sources in aviation thin-walled structures, an initial transfer matrix for assembly deviation accumulation calculation is constructed;

[0076] S4: Based on the initial transfer matrix used for assembly deviation accumulation calculation and the multi-physics field coupling deviation value of the assembly process, the deviation transfer factor is dynamically updated and the initial transfer matrix is ​​corrected to generate a deviation transfer matrix that integrates the assembly deformation, accurately calculating and obtaining the assembly coordination error at the key feature points required by the assembly process;

[0077] S5: Obtain the discrete point data of key feature errors on the assembly surface of aviation thin-walled structures through the assembly coordination errors at key feature points in the assembly process requirements, construct a thin plate spline interpolation function, and obtain an interpolation surface that can reflect the true state of error accumulation;

[0078] S6: Using the stability entropy function, a comprehensive evaluation system is established with the assembly error value as the dominant indicator and the local entropy value as the additional indicator. The interpolation surface that can reflect the true state of error accumulation is used to quantitatively evaluate the cumulative numerical value and distribution of the assembly error of the thin-walled curved surface structure under the current transmission path, and the optimal assembly sequence is screened out. If the assembly accuracy requirements are not met, the assembly process and parameters are further optimized and improved.

[0079] Said S1 specifically includes:

[0080] S11: Based on the assembly accuracy requirements in the assembly process documents and targeting the assembly goal of shape accuracy, the key features of aviation thin-walled curved surface structures are classified, including positioning features on parts and fixtures, connection features between parts, and surface shape measurement features during and after assembly. The error sources of aviation thin-walled curved surface parts are identified, including manufacturing errors of parts, positioning errors of tooling, fastening connection errors between components, and springback errors of aviation thin-walled structures during release.

[0081] S12: Considering the thin-walled, weak rigidity, and easy deformation characteristics of many aviation composite curved surface parts, the coupling effects of various physical fields such as gravity field, manufacturing error field, deformation field, and stress field in the assembly process are analyzed. By pre-setting key points on the assembly curved surface shape and utilizing the super element stiffness matrix theory in finite element analysis, the stiffness matrix of aviation thin-walled structures is simplified and segmented. An assembly deviation mechanics model for aviation thin-walled structures in the positioning-clamping connection-release and rebound stages is established. The relationship between the deformation of thin-walled curved surface parts and the forces acting on them is obtained, and the changing states of multiple types of key features at each assembly stage are clarified.

[0082] S13: Based on the small displacement screw theory, the six-degree-of-freedom screw parameters of the variable geometry are described to quantitatively characterize the changes in the manufacturing error sources, tooling positioning error sources, and assembly deformation error sources during the assembly process, expressed as:

[0083] ξ=[δ a ,δ β ,δ γ ,δ u ,δ ν ,δ w ] T

[0084] When establishing the assembly deviation mechanical model of the positioning-clamping connection-release rebound stage of the aviation thin-walled structure in S12, the Python programming language can be used to carry out secondary development of the finite element simulation analysis software ABAQUS to achieve rapid reading and generation of assembly deviation coupling simulation information. Specifically, first, after using the data reading function in Python to read the constitutive relationship and initial manufacturing, assembly positioning, and assembly deformation deviation data files in different formats, they are converted into matrices or arrays according to the constitutive relationship expression; secondly, based on the imported data and established logic, the parameters are automatically configured and the deviation coupling analysis is started; thereafter, the result file or database is located by relying on Python data processing and file operation capabilities, and the data is traversed and filtered through specific code to extract the required information and generate the deviation coupling value.

[0085] The S2 specifically includes:

[0086] S21: Combine the assembly process deformation information calculated in S12 with the measured information on component manufacturing errors to obtain the actual changes of each key assembly feature. This is used to construct the true geometric fit constraint relationship between features, such as surface fit relationship, plane fit relationship, cylindrical fit relationship, axis coaxial relationship, etc., and obtain the actual change constraint direction of various flexible fit surfaces.

[0087] S22: Using polychromatic set theory, we describe the functional characteristics of flexible aerospace thin-walled structures, including assembly relationships, mating surface types, and constraint directions. We obtain the transfer properties and degree-of-freedom constraint states of each error source and construct a flexible mating surface symbolic representation matrix. This matrix integrates the flexible mating surface type coding, direction feature coding, and constraint attribute coding to achieve semantic expression of the assembly relationships of flexible aerospace thin-walled structures.

[0088] S23: Within the entire aerospace thin-walled structure, the initial reference components and final precision output components are clearly defined. Based on the different functional requirements of the flexible mating surfaces, the order of ensuring positioning accuracy is determined through the rational application of process methods. Subsequently, combining assembly positioning and mating priorities, a flexible mating surface transfer attribute matrix is ​​constructed in descending order. Error transfer path searches for the flexible aerospace thin-walled structure are then performed sequentially to obtain multiple transfer paths for each error component.

[0089] S24: Further integrate the actual assembly conditions, analyze and obtain all the error transmission paths of the parts, and combine the deviation values ​​under the multi-physical field coupling effect to perform discrimination and screening, retaining a small number of error transmission paths that meet the assembly accuracy requirements, and using the tree diagram method to construct the error transmission paths between the various error sources of the flexible aviation thin-walled structure, intuitively expressing the transmission process of the assembly error.

[0090] The flexible mating surface symbol representation matrix of the aviation thin-walled structure in S23 includes information such as the geometric shape information of the joint surface between assembly features, assembly connection information, and feature change direction, and is expressed as follows: Figure 3 shown.

[0091] The S3 specifically includes:

[0092] S31: Based on the key features on the mating surfaces of components, the small displacement screw theory is used to convert the error variation of key features into an error screw model matrix. This is then mapped to the tolerance domain using inequality constraints to construct an error screw model for typical geometric features. By achieving a unified expression of dimensional tolerances and form and position tolerances, the positional offset and posture deviation generated by components during the manufacturing process can be quantitatively described.

[0093] S32: Using the theory of homogeneous coordinate transformation, based on the changing state of key features in S1 and the cumulative transmission path of error sources in S2, the spatial posture transmission relationship between the various components of aviation thin-walled structures is described in matrix form. By describing the coupled transmission and accumulation process of the error components in the error spinor model of each component in the assembly constraint direction, the aviation thin-walled structure deviation transmission calculation matrix is ​​constructed as the initial transfer matrix for the deviation accumulation calculation of the entire aviation thin-walled structure.

[0094] The variation deviation of the thin-walled workpiece surface feature in S31 needs to be decomposed into the rotational motion around the three coordinate axes θ=(dθ x , dθ y , dθ z ) and the translational motion along the three coordinate axes d = (dx, dy, dz), thereby completely describing its spatial changes.

[0095] The S4 specifically includes:

[0096] S41: Based on the initial deviation transfer calculation matrix in S3, according to the physical deformation information during the assembly process of aviation thin-walled structures, the discrete node coordinates A of the key assembly feature mating surfaces after assembly deformation are extracted. di (x di ,y di ,z di );

[0097] S42: Based on the node coordinate values, calculate the geometric deviation ΔA of the size, shape, position and posture of the functional feature matching surface through the spatial position mapping relationship between the ideal surface and the fitting surface. di (x di ,y di ,z di ), obtain the error small displacement screw model that integrates deformation factors in the assembly process, and accurately express the geometric error transmission state in each assembly process under the current assembly sequence;

[0098] S43: Under the current assembly process, a deformation surface compensation mechanism under external loads is constructed to obtain the "secondary deformation" information of key features in the assembly process. This is used to dynamically update and correct the specific values ​​in the constructed initial geometric deviation transfer calculation matrix. An assembly deviation transfer calculation matrix model that integrates deformation factors and manufacturing errors is established to obtain the assembly deviation transfer calculation matrix of flexible aviation thin-walled structures that integrates deformation errors.

[0099] S44: Applying error flow theory and using a linear discrete state space model, a deviation transfer model for component assembly processes suitable for multiple assembly processes is constructed. By clearly expressing the error state of the aviation thin-walled structure in the current assembly process, the error state of the aviation thin-walled structure in the previous assembly process, and the relationship between the multi-source errors introduced by the newly assembled components in the current assembly process, the cumulative value of the key characteristic errors of the aviation thin-walled structure corresponding to the deviation transfer matrix under a specific assembly sequence is solved, and the assembly coordination error ▽δ between the key characteristic points required by the assembly process is further accurately calculated. An,Bn ″.

[0100] The assembly coordination error ▽δ in S44 An,BnThe calculation of ″ is based on the cumulative assembly error Δδ of two coordinated aviation thin-walled structures A and B. An ″、Δδ Bn ″ is accurately obtained, specifically, it is calculated as: ▽δ An,Bn ″=|Δδ An ″-Δδ Bn ″|.

[0101] The S5 specifically includes:

[0102] S51: Obtain discrete point data of key feature errors on the assembly surface of thin-walled aviation structures by calculating assembly coordination errors at key feature points in assembly process requirements. Apply the mathematical principle of thin-plate spline interpolation functions and use measured force and position data of discrete key feature points on thin-walled curved surface components to construct a known point set, set the horizontal and vertical coordinate ranges of the area to be interpolated, and generate an interpolation grid within a certain step size range. Subsequently, a thin-plate spline basis function method is used to calculate and obtain the distance matrix from the points to be interpolated to the known points, providing core data for the interpolation matrix.

[0103] S52: Construct a block coefficient matrix containing thin plate spline basis function terms and low-order polynomial terms. Determine the interpolation coefficients by solving a constrained linear equation system through matrix operations. This allows for the construction and solution of the thin plate spline interpolation function matrix and the reconstruction of a three-dimensional surface that reflects the cumulative state of panel assembly errors.

[0104] S53: Use the interpolation coefficients to calculate the z-value matrix of the points to be interpolated, draw a three-dimensional scatter plot of the points to be interpolated and the original data points, and generate the interpolation surface of the thin-walled structure and visualize it, intuitively presenting the error distribution law of the surface of the curved thin-walled workpiece.

[0105] The S6 specifically includes:

[0106] S61: Analyze the evaluation requirements of the cumulative effect of surface assembly errors on thin-walled workpieces and establish the relationship between the distribution uniformity of surface shape errors and the assembly quality of aviation thin-walled structures;

[0107] S62: Based on the stability entropy function and the evaluation process of surface error distribution, a comprehensive evaluation system is established with the assembly error transfer cumulative value as the main evaluation indicator and the convex hull local entropy value as an additional evaluation indicator. Quantitative analysis is performed on the fitted thin-wall interpolation surface to achieve a quantitative assessment of the thin-wall assembly cumulative error and its distribution under the current transfer path.

[0108] S63: sequentially calculating entropy values ​​corresponding to different assembly sequences, sorting multiple assembly error transmission paths according to their values, and selecting assembly sequences with higher assembly performance;

[0109] S64: Compare the assembly accuracy values ​​under different assembly sequences. If the assembly requirements are not met, it is necessary to further optimize the process parameters and improve the assembly process from the assembly process level. Subsequently, virtual simulation verification and other means can be used to effectively improve the assembly accuracy of thin-walled parts.

[0110] The calculation of the stability entropy function in S62 is input with the error value Δz of different measurement points of the key feature in the z direction. i The normalized value Δz i ′, the specific calculation process is:

[0111]

[0112] Where Δz i is the error value of the i-th measuring point in the evaluation coordinate, Δz′ i is the normalized value of the i-th measurement point.

[0113] The entropy of the measurement point is:

[0114]

[0115] The corresponding extreme entropy is:

[0116] H max =log2m

[0117] The normalized entropy value is:

[0118]

[0119] The larger the normalized entropy value, the more uniform the distribution of the actual component surface shape error, which means that the impact on the assembly quality is smaller and better assembly accuracy will be achieved.

[0120] The construction of the comprehensive evaluation system in S62 can be divided into five steps: (1) using the relative entropy value calculation method to perform a preliminary evaluation of the surface shape distribution error; (2) when the result of the preliminary entropy evaluation shows that the surface shape error is non-uniformly distributed, the eight-neighborhood search method is used to search for the convex hull on the surface shape; (3) based on the searched convex hull, the top plane is constructed, and the maximum shape error of the assembled curved surface is obtained by combining the ideal surface calculation; (4) after calculating the assembly error on the flexible thin-walled parts, the local entropy analysis is performed on the convex hull area to obtain the local entropy value of each convex hull; (5) based on the entropy value calculation result, the comprehensive evaluation index of the assembly surface shape distribution error is obtained: I c =[θ S ,min(H MS )],θ S is the calculation result of assembly error, which is used as the leading evaluation index; min(H MS) is the minimum value of the local entropy, which can be used to judge the uniformity of the distribution of the convex hull and serve as an additional evaluation indicator.

[0121] The top plane in S62 is defined as a virtual plane, which is determined by three contact convex points (including edge points) on the actual component surface. All convex points on the actual component surface are located on the same side of the plane, and the geometric center of the actual component surface is located inside the triangle formed by these three convex points.

[0122] The optimization of the assembly process parameters and the assembly process in S64 can specifically be aimed at effectively improving the assembly accuracy of thin-walled parts, starting from three aspects: adjusting the assembly sequence, adjusting the positioning scheme, and adjusting the tolerance range.

[0123] The present invention also provides a calculation and evaluation system for the cumulative transmission of coordination errors in the assembly of thin-walled curved surface structures in aviation, the calculation and evaluation system for the cumulative transmission of coordination errors in the assembly of thin-walled curved surface structures in aviation comprising:

[0124] The error source transfer path model construction module is used to combine the deformation of the assembly process with the measured information of component manufacturing errors to construct the transfer path model between the various error sources of flexible aviation thin-walled structures;

[0125] The error transfer matrix construction and update module is used to characterize the dynamic changes of the transfer factors of each error source during the assembly process, generate the deviation transfer matrix that integrates the assembly deformation, and accurately calculate the assembly coordination error at key feature points;

[0126] The error transfer evaluation and process optimization module is used to construct an interpolation surface of the actual state of assembly error accumulation, and to quantitatively evaluate and optimize the assembly error accumulation and distribution of thin-walled surfaces.

[0127] The present invention provides a calculation and evaluation method for the cumulative transfer of coordination errors in the assembly of aviation thin-walled curved surface structures. Figure 2 The following is a flow chart of the specific implementation of this solution in this embodiment. The overall idea adopted by the present invention to solve its technical problems is:

[0128] First, a mechanical deformation analysis model for the assembly process is established, and an assembly error transmission path analysis method considering the multi-physics coupling effect is proposed. Specifically, the assembly error sources of thin-walled curved surface parts in aviation are identified, and a mechanical model of assembly deviation in the positioning-clamping connection-release and rebound stages of aviation thin-walled structures is established using super-element stiffness matrix theory. This model reveals the generation mechanism of manufacturing error, positioning error, and deformation error of assembled parts. With the help of finite element software, the deviation values ​​under the multi-physics coupling effect are obtained. Based on polychromatic set theory, a flexible mating surface symbol matrix is ​​constructed to describe the functional characteristics such as the assembly relationship, mating surface type, and orientation of flexible aviation thin-walled structures. An assembly error transmission path model is established to analyze and obtain all the error transmission paths of the parts. Combined with the deviation values ​​under the multi-physics coupling effect, the dominant error transmission path of aviation thin-walled structures is accurately analyzed and obtained, which can provide a basis for the calculation of assembly error accumulation.

[0129] Secondly, by integrating deformation factors in the assembly process with measured assembly data, a dynamic update mechanism for the assembly deviation transfer calculation matrix that takes assembly deformation into account is proposed. Based on the small displacement spinor theory and homogeneous transformation theory, an initial assembly deviation transfer calculation matrix is ​​constructed, and a deviation transfer calculation matrix is ​​constructed. By combining measured data with multi-physics field coupling simulation results, the deformation information is converted into a deviation transfer coefficient matrix, generating an assembly deviation transfer calculation matrix that incorporates deformation errors. By real-time monitoring of the geometric deviations, deformation amounts, and key assembly feature quality data of each assembly unit during the assembly process, a dynamic update mechanism for the assembly deviation transfer calculation matrix is ​​established, enabling accurate calculation of error transfer modeling.

[0130] Finally, the data on discrete points of key feature errors in the assembly surfaces of multiple thin-walled aerospace structures were converted into surface variation data, and a quantitative evaluation method for the assembly shape errors of thin-walled composite materials was proposed. Based on the measured data of a large number of key feature points on thin-wall panels, a thin-plate spline interpolation function was constructed to model the thin-wall panels, accurately reconstructing a three-dimensional surface that reflects the cumulative state of panel assembly errors. A quantitative evaluation method for the assembly shape errors of thin-walled composite materials was proposed, and the entropy function was used to evaluate the distribution of surface errors. Quantitative analysis was then performed on the fitted surfaces to achieve a quantitative assessment of the cumulative errors of thin-wall assembly under different assembly sequences, which serves as a basis for optimizing assembly processes and process parameters.

[0131] Example 1:

[0132] In this embodiment, a certain type of composite material wing box component assembly application is taken as an example ( Figure 5). First, the typical wing box assembly process scheme is analyzed, specifically including the analysis of the wing box and tooling structure, assembly sequence analysis, tooling equipment layout, assembly tolerance information analysis, etc., to clarify the source of error analysis data; secondly, the wing box structure and wing box wall panel (positioning, connection release) assembly deformation state are analyzed, and the real-time data of each assembly quality data under the assembly process is analyzed and extracted. The wing assembly shape step difference is calculated through the constructed transfer path and assembly deviation transfer calculation matrix, and compared with the simulation results to verify the feasibility of the deviation transfer path analysis method and the deviation transfer calculation matrix; finally, the assembly shape error quantitative evaluation method is used to evaluate the upper wall panel skin under different assembly sequences, and compared with the measured assembly performance of each skin surface to verify the effectiveness of the evaluation method, and optimize its assembly process from the aspects of the assembly sequence and geometric tolerance of the wing box parts to achieve the improvement of the assembly accuracy of thin-walled parts, thereby providing a scientific basis and technical guidance for the precise assembly of thin-walled curved surface structures of aviation composite materials. The aviation thin-walled curved surface structure assembly coordination error cumulative transfer calculation and evaluation technology includes the following steps:

[0133] Specifically, the Figure 5 The wing box, a structural framework within the aircraft wing, enhances wing strength and rigidity during service. It primarily comprises machined metal walls, ribs, stringers, and composite skin panels. During the acceptance process for this type of wing box, the primary focus is on testing the assembly accuracy of the seam difference between the two upper skin panels to ensure that the wing box's assembly quality meets acceptance standards.

[0134] Furthermore, the Figure 4 The wing box assembly tooling is equipped with a clamping unit using a vacuum suction cup. The displacement sensor monitors and precisely controls the amount of clamping and expansion in real time to ensure that the components fit tightly while avoiding excessive pressure. At the same time, the tooling is equipped with a measuring platform with a six-degree-of-freedom force sensor, which can fully sense the assembly force conditions and provide accurate data basis for deviation adjustment. Figure 5 Wing box products Figure 4 During the assembly process on the tooling, measuring equipment such as laser trackers, six-dimensional force sensors, displacement sensors, GAPGUN (gap-step difference measurement instrument), and strain gauge rosettes are used on-site. The wing box is assembled based on the framework formed by end ribs 1 and 2, the front beam, and the rear beam. Typically, internal ribs 1 and 2 are installed first, followed by lower panel stringers 1 and 2, and upper panel stringers 1 and 2. Finally, the composite lower panel skin is installed, and finally, the composite upper panel skin is installed.

[0135] Furthermore, based on the statistical tolerance information of the wing box components, and analyzing the step difference of the assembly seam between the two upper wall panels P7 and P8, the effective error transmission path corresponding to the error components α, β, and w in the z direction from P7 to P8 is solved. Figure 4 The part number of the wing box in the wing box is used to establish the flexible mating surface symbol matrix of the wing box aviation thin-walled structure, such as Figure 6 As shown, P is the component number, and F is the mating surface between the components. Secondly, in the calculation process of the wing box assembly step difference, it is necessary to solve the deviation of the upper wall panel skin P7 and P8 in the Z direction respectively, and then solve the assembly step difference of the upper wall panel skin P7 and P8 in the Z direction. The reference part of the upper wall panel skin P7 and P8 assembly error transmission path is the front beam P1, and the precision output part is the upper wall panel skin P7 and P8. According to the above assembly process and the flexible mating surface symbol matrix, the upper wall panel skin P7 assembly error transmission path from P1 to P7 is searched and obtained as follows Figure 7 shown.

[0136] Furthermore, based on the obtained wing box assembly error transfer path, the assembly error of the upper panel skin P7 was expanded and calculated using the assembly deviation transfer matrix. The error spinor model of each component's functional characteristic error was converted into the error transfer matrix using the deviation transfer factor matrix, as shown in Table 1.

[0137] Table 1 Matrix form of deviation transfer factors of functional characteristics of each component of the wing box

[0138]

[0139] Furthermore, the assembly error FR of the wing box upper panel skin P7 is obtained by combining the coordinate system of the key feature points of each component of the wing box.

[0140]

[0141] The above calculations show that the assembly error of the wing box upper panel skin P7 in the Z direction is 1.1781 mm. Similarly, the assembly error of the upper panel skin P8 in the Z direction can be calculated to be 1.2013 mm. Using the probability method and the assembly coordination error calculation formula, the assembly step difference ε = 1.7396 between upper panels P7 and P8 was calculated. This was compared with the simulation analysis result of 1.6112 mm. The results show that the two error values ​​are very close, with a similarity of 92.6189%. This comparison effectively verifies the feasibility of this method.

[0142] Furthermore, based on the measured data on the upper panel skin under different assembly orders, the thin plate spline interpolation function is used to construct the surface model. According to the measured force and position data of the key feature points on the skin, the thin plate spline interpolation function is used to calculate the z value of the interpolation point, and the interpolation surfaces under four assembly orders are generated and visualized, as shown in the figure. Figure 7 shown.

[0143] Furthermore, a quantitative evaluation of the four actual surface assembly states of the upper panel skin was performed. The Z index values ​​of all measurement points were transferred to the evaluation coordinates. After obtaining the corresponding function values, the overall entropy of the actual surface state of the upper panel skin under the four different assembly sequences was calculated to perform a preliminary evaluation of the panel assembly shape error. The results are shown in Table 2.

[0144] Table 2 Comprehensive entropy evaluation results of four actual surface states of the upper wall panel skin

[0145]

[0146] Furthermore, according to the entropy function evaluation method, the comprehensive evaluation index attribute curves of PCFs under four different assembly orders are as follows: Figure 9 shown.

[0147] from Figure 9 The data analysis shows that each PCF exhibits different error characteristics under different assembly sequences. PCF1, in assembly sequence ①, demonstrates excellent assembly quality. PCF1, in assembly sequence ①, has the smallest maximum absolute error among the PCFs and the best error distribution uniformity. These two factors together demonstrate that PCF1 has the best assembly quality and is therefore considered one of the PCFs with the highest assembly accuracy.

[0148] Comparing PCF2 and PCF3, while PCF2's error distribution uniformity effect is slightly less than PCF3's, meaning its error distribution is slightly more concentrated, PCF2's absolute maximum error is slightly smaller than PCF3's. In the assembly process, the absolute maximum error directly affects the risk of assembly failure due to extreme deviations; the smaller the value, the lower the risk. Compared to the impact of error distribution uniformity on assembly quality, the absolute maximum error, a leading evaluation metric, is relatively more important. Therefore, considering these two key factors, PCF2 outperforms PCF3 in terms of assembly quality.

[0149] Based on the above, a detailed analysis of each PCF reveals that the order of assembly quality, from highest to lowest, is: PCF1 > PCF2 > PCF3 > PCF4. This evaluation method accurately identifies surfaces with high assembly performance, and is essentially equivalent to the assembly performance of each skin surface analyzed previously. Furthermore, this method provides a more comprehensive and standardized evaluation, validating its effectiveness.

[0150] Furthermore, optimizing assembly deviations can be achieved by adjusting the assembly sequence, the positioning scheme, and the tolerance range. However, due to limitations in tooling and riveting processes, effectively adjusting the positioning scheme often requires the development of new tooling, making it relatively difficult to adjust the positioning scheme in practice. Therefore, the present invention optimizes the assembly accuracy of the wing box by first optimizing the assembly sequence and then reducing the dimensional tolerances of the assembled components.

[0151] Specifically, based on the quantitative evaluation of the cumulative assembly errors of thin-walled surfaces under different assembly sequences, the optimal assembly sequence is analyzed as assembly path ①: front spar P1 - end rib P3 - upper panel stringer P11 - upper panel skin P7. This, combined with the previously reported results of the prediction and evaluation of wing box assembly deviation transfer, and using the wing box assembly deviation simulation sensitivity analysis report, it is determined that the upper panel skin profile tolerance range has the greatest contribution to the deviation of the skin assembly step.

[0152] The present invention conceives two solutions in terms of tolerance optimization:

[0153] Option 1: Adjust only the tolerance range of the upper wall panel skin, while keeping the tolerances of other components unchanged. Use simulation analysis to obtain the assembly deviation results after tolerance optimization under the single deviation adjustment.

[0154] Option 2: Within the simulation analysis software, boundary conditions are set as optimization targets and tolerance optimization is performed. (The VSA tolerance simulation software comprehensively analyzes the assembly sequence plan, assembly process information, and component tolerances to determine the optimal tolerance adjustments for all wing box components.) This results in an assembly error result with optimized tolerances after adjusting for all deviations. Detailed tolerance adjustment information is shown in Table 3.

[0155] Table 3 Tolerance information of wing box component feature points before and after adjustment

[0156]

[0157] Proposing these two solutions has a dual significance: on the one hand, it is to verify the results obtained by the error accumulation analysis method mentioned above. Based on the prediction and evaluation analysis of the wing box assembly deviation transfer conducted in the previous article, it can be seen that the upper wall panel skin profile tolerance range contributes the most to the deviation of the skin assembly step difference. Through solution one, we can focus on the upper wall panel skin tolerance adjustment and accurately verify this key conclusion; solution two starts from the overall situation and further verifies this conclusion by comparing with solution one. On the other hand, it can better achieve the optimization and improvement of assembly quality. By comparing these two solutions, the solution with more significant optimization effect is selected and applied to the process optimization link to effectively improve the assembly quality.

[0158] Furthermore, after completing the above parameter settings, simulation calculation analysis is carried out according to the same calculation conditions and processes, and finally the corresponding result report is output so that the optimization effect can be further evaluated based on the report content. Figure 10 、 Figure 11 They are the results before and after single adjustment and comprehensive adjustment of wing box assembly deviation.

[0159] Furthermore, after adopting plan one for single adjustment, the assembly error of the wall panel step difference was significantly reduced from 1.6112mm to 0.9881mm, a decrease of 38.67%, successfully meeting the assembly accuracy standard of 1mm; and after implementing comprehensive adjustment using plan two, the assembly error of the wall panel step difference was further reduced from 1.6112mm to 0.9611mm, a reduction of 40.35%, also meeting the assembly accuracy requirement of 1mm.

[0160] Furthermore, by comparing the two solutions, it is not difficult to find that Solution 1, which only adjusts the tolerance of a single upper wall panel skin, and Solution 2, which comprehensively adjusts all deviations, are relatively close in optimization effect, and both can effectively control the assembly quality of the wing box wall panel, greatly improving assembly efficiency and accuracy. This shows that during the assembly process, it is necessary to attach great importance to the positioning and connection links of the skin structure, and avoid excessive deformation as much as possible to ensure the assembly quality of the step difference between the upper wall panel skins. If the cost and other relevant factors are comprehensively weighed, Solution 1 shows a higher cost-effectiveness while achieving a good assembly effect, and its advantages are more prominent.

[0161] The above describes in detail a method and system for calculating and evaluating the cumulative transfer of coordination errors in the assembly of thin-walled curved surface structures in aviation, as provided in the embodiments of this application. The description of the above embodiments is intended only to facilitate understanding of the method and core concept of this application. Furthermore, those skilled in the art will appreciate that variations in the specific implementation and scope of application may occur based on the concepts of this application. Therefore, the contents of this specification should not be construed as limiting this application.

[0162] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different nouns to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. For example, "including" and "comprising" mentioned throughout the specification and claims are open-ended terms, so they should be interpreted as "including / including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve the technical problems within a certain error range and basically achieve the technical effects. The subsequent description in the specification is a preferred embodiment of the present application, but the description is for the purpose of illustrating the general principles of the present application, and is not used to limit the scope of the present application. The scope of protection of the present application shall be as defined in the attached claims.

[0163] It should also be noted that the terms "include," "comprises," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a product or system comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such product or system. In the absence of further limitations, an element defined by the phrase "comprises a..." does not exclude the presence of other identical elements in the product or system comprising the element.

[0164] It should be understood that the term "and / or" as used herein is merely a description of the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0165] The above description shows and describes several preferred embodiments of the present application. However, as previously mentioned, it should be understood that the present application is not limited to the form disclosed herein and should not be construed as excluding other embodiments. Instead, the present application can be used in various other combinations, modifications, and environments and can be modified within the scope of the application concept described herein through the above teachings or technology or knowledge in the relevant field. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present application should be protected by the claims appended hereto.

Claims

1. A calculation and evaluation method for the cumulative transfer of coordination errors in the assembly of thin-walled curved surface structures in aviation, which is used to reduce the errors of thin-walled curved surface structures in aviation and improve the accuracy of assembly parts. It is characterized by: The proposed method for calculating and evaluating the cumulative transmission of coordinated errors in the assembly of thin-walled curved surface structures in aviation is firstly performed by analyzing the coupling effects of the thin-walled curved surface structures in multiple physical fields to characterize multi-source errors and construct assembly error transmission paths. Secondly, based on the characteristics of the thin-walled curved surface structures in aviation and the assembly error transmission paths, the error transmission values ​​between the assembly parts are quantitatively characterized. The assembly deviation transmission calculation matrix is ​​updated in combination with the real-time mechanical state of the thin-walled structures in aviation to achieve accurate calculation of assembly errors. Thirdly, the cumulative effects of the shape errors in the assembly of composite thin-walled surfaces are quantitatively evaluated in combination with the measured force and position data of key characteristic points. Finally, based on the results of accurate calculation and quantitative evaluation of assembly errors, the assembly process is optimized.

2. The calculation and evaluation method for cumulative transfer of coordination errors in assembly of thin-walled curved surface structures of aviation according to claim 1 is characterized in that: The calculation and evaluation method for the cumulative transfer of coordination errors in the assembly of aviation thin-walled curved surface structures comprises the following steps: S1: Analyze the multi-physics coupling effect in the assembly process of aviation thin-walled structures, establish a mechanical state model of assembly deviation of aviation thin-walled structures, and characterize the changes in error sources during the assembly process; S2: Obtain the measured information of assembly process deformation and component manufacturing errors through the changes in the error sources during the assembly process, establish a flexible mating surface symbol representation matrix, and construct multiple transmission path models between various error sources in aviation thin-walled structures through the flexible mating surface symbol representation matrix; S3: Based on the theory of small displacement screws and homogeneous coordinate transformation, and following the multiple transfer path models between various error sources in aviation thin-walled structures, an initial transfer matrix for assembly deviation accumulation calculation is constructed; S4: Based on the initial transfer matrix used for assembly deviation accumulation calculation and the multi-physics field coupling deviation value of the assembly process, the deviation transfer factor is dynamically updated and the initial transfer matrix is ​​corrected to generate a deviation transfer matrix that integrates the assembly deformation, accurately calculating and obtaining the assembly coordination error at the key feature points required by the assembly process; S5: Obtain the discrete point data of key feature errors on the assembly surface of aviation thin-walled structures through the assembly coordination errors at key feature points in the assembly process requirements, construct a thin plate spline interpolation function, and obtain an interpolation surface that can reflect the true state of error accumulation; S6: Using the stability entropy function, a comprehensive evaluation system is established with the assembly error value as the dominant indicator and the local entropy value as the additional indicator. The interpolation surface that can reflect the true state of error accumulation is used to quantitatively evaluate the cumulative numerical value and distribution of the assembly error of the thin-walled curved surface structure under the current transmission path, and the optimal assembly sequence is screened out. If the assembly accuracy requirements are not met, the assembly process and parameters are further optimized and improved.

3. The calculation and evaluation method for cumulative transfer of coordination errors in assembly of thin-walled curved surface structures of aviation according to claim 2, characterized in that: Said S1 specifically includes: S11: Based on the assembly accuracy requirements of aviation thin-walled structures in the assembly process, the key features of aviation thin-walled structures are classified to clarify the types of assembly error sources of aviation thin-walled structures. The key features include positioning features, connection features, and measurement features. S12: Analyze the coupling effects of gravity, manufacturing error, deformation, and stress fields during the assembly process by analyzing the types of assembly error sources for thin-walled aviation structures. Utilize the super-element stiffness matrix theory in finite element analysis to establish an assembly deviation mechanics model for the positioning, clamping, and release / springback stages of thin-walled aviation structures. This model captures the changing states of key features of different error sources at each assembly stage. S13: Based on the small displacement screw theory, the six-degree-of-freedom screw parameters of the variable geometry are described to quantitatively characterize the changes in different types of error sources during the assembly process. The different types of error sources include changes in manufacturing error sources, tooling positioning error sources, and assembly deformation error sources.

4. The calculation and evaluation method for cumulative transfer of coordination errors in assembly of thin-walled curved surface structures in aviation according to claim 3 is characterized in that: The S2 specifically includes: S21: Obtain measured information on assembly process deformation and component manufacturing errors through the changes in different types of error sources, and clarify the relationship between actual assembly changes and true geometric fit constraints; S22: Using polychromatic set theory, describe the assembly relationship between parts of aerospace thin-walled structures, the types of mating surfaces, and the functional characteristics of constraint directions, obtain the transfer properties and degree-of-freedom constraint states of different types of error sources, and construct a symbolic representation matrix for flexible mating surfaces; S23: Define the initial reference components and final precision output components in the aerospace thin-walled structure, and, in combination with assembly positioning and mating priority, construct a flexible mating surface transfer attribute matrix using the flexible mating surface symbol representation matrix results. Then, sequentially conduct an error transfer path search for the flexible aerospace thin-walled structure to obtain multiple transfer paths for each error component. S24: Analyze and obtain the error transmission paths of all components in aviation thin-walled structures, and use the deviation values ​​under the multi-physics field coupling effect to identify and screen them, retaining a small number of error transmission paths that meet the assembly accuracy requirements, and using a tree diagram method to construct the error transmission paths between the various error sources in flexible aviation thin-walled structures.

5. The calculation and evaluation method for cumulative transfer of coordination errors in assembly of thin-walled curved surface structures of aviation according to claim 4, characterized in that: The S3 specifically includes: S31: Based on the key features on the mating surfaces of components, the small displacement screw theory is used to convert the position changes of the key features into an error screw model matrix. This is then mapped to the tolerance domain using inequality constraints. An error screw model of typical functional features is constructed to quantitatively describe the positional offset and posture deviation of components during the manufacturing process. S32: Using the theory of homogeneous coordinate transformation, based on the changes in manufacturing error sources, tooling positioning error sources, and assembly deformation error sources during the assembly process in S1 and the error transmission paths between the error sources of the flexible aviation thin-walled structure in S2, the spatial posture transmission relationship between the various components of the aviation thin-walled structure is described in matrix form, and the aviation thin-walled structure deviation transfer calculation matrix is ​​constructed as the initial transfer matrix for the assembly deviation accumulation calculation.

6. The calculation and evaluation method for cumulative transfer of coordination errors in assembly of thin-walled curved surface structures in aviation according to claim 5, characterized in that: The S4 specifically includes: S41: Based on the initial transfer matrix used for assembly deviation accumulation calculation in S3, the discrete node coordinates of the mating surfaces of key assembly features after deformation are extracted according to the physical deformation information during the assembly process of the aviation thin-walled structure; S42: Based on the node coordinate values, the geometric deviations of the size, shape and position of the mating surfaces of key assembly features are calculated through the spatial position mapping relationship between the ideal surface and the fitted surface, and the error screw model of the fusion deformation factors in the assembly process is obtained; S43: An initial geometric deviation transfer calculation matrix is ​​constructed by using an error screw model that integrates deformation factors during the assembly process. A deformation surface compensation mechanism under external loads is introduced to dynamically update and correct the constructed initial geometric deviation transfer calculation matrix. An assembly deviation transfer calculation matrix model that integrates deformation factors and manufacturing errors is established to obtain an assembly deviation transfer calculation matrix that integrates deformation errors. S44: Apply error flow theory to construct a deviation transfer model for component assembly processes applicable to multiple assembly steps, calculate the error accumulation value corresponding to the deviation transfer matrix under a specific assembly sequence, and accurately calculate the assembly coordination error between key assembly features in the assembly process requirements.

7. The calculation and evaluation method for cumulative transfer of coordination errors in assembly of thin-walled curved surface structures of aviation according to claim 6, characterized in that: The S5 specifically includes: S51: Obtain discrete point data of key feature errors on the assembly surface of thin-walled aerospace structures through assembly coordination errors at key feature points in assembly process requirements. Apply the mathematical principle of thin-plate spline interpolation function, use the measured force and position data of discrete key feature points on thin-walled curved surface parts, and adopt the thin-plate spline basis function method to obtain the distance matrix from the interpolation point to the known point. S52: Construct a block coefficient matrix containing basis function terms and low-order polynomial terms, solve the constrained linear equations to determine the interpolation coefficients, implement the construction and solution of the thin plate spline interpolation function matrix, and reconstruct a three-dimensional surface that can reflect the cumulative state of the panel assembly error; S53: Use the interpolation coefficient to calculate the z value of the point to be interpolated, generate the interpolation surface of the thin-walled structure and visualize it, and intuitively present the error distribution law of the surface of the thin-walled curved surface workpiece.

8. The calculation and evaluation method for cumulative transfer of coordination errors in assembly of thin-walled curved surface structures in aviation according to claim 7, characterized in that: The S6 specifically includes: S61: Analyze the evaluation requirements of the cumulative effect of surface assembly errors on thin-walled workpieces and establish the relationship between the distribution uniformity of surface shape errors and the assembly quality of aviation thin-walled structures; S62: Based on the stability entropy function and the evaluation process of surface error distribution, a comprehensive evaluation system is established with the assembly error transfer cumulative value as the main evaluation indicator and the convex hull local entropy value as an additional evaluation indicator. Quantitative analysis is carried out on the error distribution law of the fitted curved thin-walled surface workpiece surface to achieve a quantitative assessment of the thin-wall assembly cumulative error and its distribution under the current transfer path; S63: sorting multiple assembly error transmission paths based on entropy calculation results corresponding to different assembly sequences, and selecting assembly sequences with higher assembly performance; S64: Compare the assembly accuracy values ​​under different assembly sequences. If the assembly requirements are not met, it is necessary to further optimize the process parameters and improve the assembly process from the assembly process level. The optimization of process parameters and improvement of the assembly process are specifically aimed at improving the assembly accuracy of thin-walled parts. The three solutions are adjusted from the assembly sequence, positioning scheme, and tolerance range. Subsequently, virtual simulation verification is used to achieve a rapid improvement in the assembly accuracy of thin-walled parts.

9. The calculation and evaluation method for cumulative transfer of coordination errors in assembly of thin-walled curved surface structures in aviation according to claim 8, characterized in that: The S62 specifically includes: S621: Use relative entropy method to make a preliminary evaluation of the surface shape distribution error; S622: When the result of the preliminary entropy evaluation indicates that the surface shape error is non-uniformly distributed, searching for a convex hull on the surface shape; S623: Based on the searched convex hull, a top plane is constructed, and the maximum shape error of the assembled surface is calculated in combination with the ideal surface; S623: Perform local entropy analysis on the convex hull area to obtain the local entropy value of each convex hull; S624: Obtain a comprehensive evaluation index of the assembly surface shape distribution error based on the entropy value calculation result.

10. A calculation and evaluation system for the cumulative transfer of coordination errors in the assembly of thin-walled curved surface structures in aviation, characterized in that: The aviation thin-walled structure assembly coordination error accumulation transfer calculation and evaluation system includes: The error source transfer path model construction module is used to combine the deformation of the assembly process with the measured information of component manufacturing errors to construct the transfer path model between the various error sources of flexible aviation thin-walled structures; The error transfer matrix construction and update module is used to characterize the dynamic changes of the transfer factors of each error source during the assembly process, generate the deviation transfer matrix that integrates the assembly deformation, and accurately calculate the assembly coordination error at key feature points; The error transfer evaluation and process optimization module is used to construct an interpolation surface of the actual state of assembly error accumulation, and to quantitatively evaluate and optimize the assembly error accumulation and distribution of thin-walled surfaces.

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