Assembly Deviation Analysis Method for Non-uniform Condensation of Stiffness in Ultra-large Structures

Abstract

This invention provides a method for analyzing assembly deviations in ultra-large structures with non-uniform stiffness condensation, comprising the following steps: S1: dividing the ultra-large structure into a plastic region and an ultra-large stiffened elastic region; S2: constructing a model for the non-uniform stiffness condensation of ultra-large structures suitable for the network-like concentrated distribution characteristics of assembly deviations; S3: establishing an overall stiffness model of the ultra-large structure described by the weld region and its interface; S4: considering the influence of welding deformation during the welding process, introducing a welding stress field, and establishing a welding deviation analysis model based on the deformation coordination relationship before and after assembly in the plastic region; solving for the welding deviations of the ultra-large structure, thereby realizing the prediction and analysis of assembly deviations in ultra-large stiffened structures. This invention's method for analyzing assembly deviations in ultra-large structures with non-uniform stiffness condensation enables the prediction and analysis of assembly deviations in ultra-large structures with overall flexibility and local rigidity, providing a theoretical basis for compensation and control of assembly deviations in ultra-large structures, and improving product assembly quality.

Description

Technical Field

[0001] This invention relates to the field of deviation analysis in the assembly process of flexible structures, and in particular to a method for analyzing assembly deviations of ultra-large structure stiffness non-uniform condensation. Background Technology

[0002] As a crucial component of launch vehicles, fuel tanks bear enormous static and dynamic loads during launch. The dimensional accuracy of the tank's massive structure directly impacts the overall performance of the product. Heavy-lift launch vehicle fuel tanks are constructed from massive, stiffened structures welded by friction stir. Due to their large size, thick walls, and localized non-uniformity, the influence of geometric nonlinearity is significantly amplified, resulting in a structure exhibiting overall flexibility with localized rigidity. The localized high stiffness of the massive, stiffened structure makes it difficult to release internal stresses, leading to a concentrated "network" distribution of welding deviations along the weld seams, a characteristic entirely different from that of traditional thin-walled structures. Due to the coupling of geometric nonlinearity and welding deformation during the welding process, the deviations caused by already released internal stresses are more complexly affected by the localized structural stiffness, making assembly dimensions and accuracy difficult to predict and control.

[0003] Traditional precision control in propellant tank manufacturing relies primarily on repeated adjustments to ensure accuracy requirements, lacking systematic deviation analysis and control methods. This leads to long product development cycles and poor consistency. Currently, flexible deviation analysis methods for large aerospace structures mainly include point-to-point deviation analysis based on the influence coefficient method and field-to-field deviation analysis based on the characteristics of component deviation distribution. Neither of these methods is suitable for predicting and analyzing deviations in the assembly of large, locally rigid, reinforced "mesh" structures. Therefore, it is necessary to develop new deviation prediction and analysis methods specifically for the stiffness and deviation characteristics of large structures. This will provide a theoretical basis for deviation compensation and precision control in the assembly of large structures, enabling high-precision and high-efficiency assembly of heavy-duty rocket propellant tanks. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, this invention provides an assembly deviation analysis method for non-uniform condensation of stiffness in ultra-large structures. This method enables the prediction and analysis of assembly deviations in ultra-large structures that are flexible overall but rigid locally, providing a theoretical basis for compensation and control of assembly deviations in ultra-large structures and improving product assembly quality.

[0005] To achieve the above objectives, this invention provides a method for analyzing assembly deviations in ultra-large structural stiffness non-uniform condensation, comprising the following steps:

[0006] S1: The super-large structure is divided into a plastic region and a super-large reinforced elastic region. The plastic region is the weld of the super-large structure and its adjacent area, and the super-large reinforced elastic region is far away from the weld.

[0007] S2: Construct a non-uniform condensation model for the stiffness of ultra-large structures that is suitable for the network-like concentrated distribution characteristics of assembly deviations in ultra-large structures.

[0008] S3: Construct a stiffness model under geometric nonlinearity for the weld region, and combine the stiffness model with the condensed stiffness matrix of the super-large stiffened structure to establish an overall stiffness model of the super-large structure described by the weld region and its interface.

[0009] S4: Considering the influence of welding deformation during the welding process, a welding stress field is introduced, and a welding deviation analysis model is established based on the deformation coordination relationship before and after assembly in the plastic region; the welding deviation of the ultra-large structure is solved to realize the prediction and analysis of the assembly deviation of the ultra-large reinforced structure.

[0010] Preferably, in step S1:

[0011] Based on the process parameters of friction stir welding, the stress distribution of the super-large structure welded assembly is preliminarily predicted through finite element analysis. The stress concentration distribution area at the weld is the plastic region, and the area away from the weld is the super-large reinforced elastic region.

[0012] Preferably, the construction of the super-large structural stiffness non-uniform condensation model includes the following steps:

[0013] S21: Based on the theory of continuum mechanics, a single-element nonlinear stiffness matrix, denoted as K, is derived for the aforementioned ultra-large reinforced region. (1) ;

[0014] S22: For the nonlinear stiffness matrix K of the element (1) Divide the space into blocks according to the interface degree of freedom r and the first internal degree of freedom s, that is:

[0015]

[0016] Among them, K ss (1) K represents the stiffness matrix corresponding to the first internal degree of freedom. rr (1) K represents the stiffness matrix corresponding to the interface degrees of freedom. sr (1) With K rs (1) This represents the block stiffness matrix that is related to both the first internal degree of freedom and the interface degree of freedom.

[0017] S23: Using the interface degree of freedom r to characterize the first internal degree of freedom s, perform stiffness reduction on the stiffness matrix that is only related to the first internal degree of freedom to form a condensed stiffness matrix of the ultra-large stiffened structure.

[0018]

[0019] Among them, K rr (1) Krs (1) K ss (1) K sr (1) All are related to the configuration of the elastic region and participate in the iterative calculation of the assembly process.

[0020] Preferably, the establishment of the overall stiffness model of the ultra-large structure includes the following steps:

[0021] S31: To address the geometric nonlinear deformation characteristics of the weld region during the assembly process, a stiffness matrix K for the weld region related to the structural configuration is established based on large deformation theory. (2) ;

[0022] S32: The stiffness matrix K of the weld region... (2) Divide the space into blocks according to the interface degree of freedom r and the second internal degree of freedom m;

[0023] S33: Combine the stiffness matrix of the weld region with the condensed stiffness matrix of the super-large stiffened structure to establish the overall stiffness matrix K of the super-large structure.

[0024]

[0025] Among them, K mm (2) K represents the stiffness matrix corresponding to the second internal degree of freedom. rr (2) K represents the stiffness matrix corresponding to the interface degrees of freedom. mr (2) With K rm (2) This represents the block stiffness matrix that is related to both the second internal degree of freedom and the interface degree of freedom.

[0026] Preferably, the establishment of the welding deviation analysis model includes the following steps:

[0027] S41: Establish a welding stress field characterization method for the long-range friction stir welding process of the super-large structure to provide welding input for the assembly deviation analysis of the super-large structure;

[0028] S42: Based on the deformation coordination relationship of the weld area before and after assembly, a nonlinear equilibrium equation for the assembly process is constructed to form an assembly deviation analysis model for ultra-large structures.

[0029] S43: Iteratively solve the nonlinear equilibrium equation of the assembly process to obtain the overall assembly deviation of the ultra-large structure;

[0030] S44: Treat the current assembly as a new part and re-execute S41 with another part that has an assembly relationship until the entire assembly is completed, thereby obtaining the overall assembly deviation V of the storage tank of the assembly after the ultra-large structure is assembled. as .

[0031] Preferably, the welding stress field characterization is achieved by establishing a local small model of the weld, performing thermo-elastic-plastic analysis on the local small model of the weld, and realizing stress prediction of the long-range welding process based on the welding stress mapping relationship from the local small model of the weld to the long-range weld model.

[0032] Preferably, the nonlinear equilibrium equation for the assembly process is:

[0033]

[0034] in w K, A K and B K represents the stiffness matrix of the weld region of the assembly and the part after the superposition of condensation and stiffness. w V. A V and B V represents the deviation corresponding to the degree of freedom in the weld area.

[0035] Preferably, the iterative solution of the nonlinear equilibrium equation includes the following steps:

[0036] S431: Solve for the stiffness matrix of the aforementioned ultra-large structure under small deformation, and superimpose the stiffness matrix of the weld region. w K (0) Condensation stiffness matrix of reinforced region and Solving the equilibrium equations yields the first approximate solution for the weld zone deviation. w V (1) ;

[0037] S432: The first approximate solution based on the weld area deviation w V (1) Given the interface displacement boundary conditions, the inverse solution approximates the deviation of the condensed region of the part. A1 V (1) and B1 V (1) ;

[0038] S433: Based on the approximate solution of the deviation in the condensed region of the part. A1 V (1) , B1 V (1) Calculate the stiffness matrix of the elastic region of the part. A1 K (1) , B1 K (1)Based on this, a second condensation process is performed to obtain the condensation stiffness matrix of the part. and

[0039] S434: Based on the first approximate solution of the weld zone deviation w V (1) Calculate the stiffness matrix of the weld region, and then superimpose the stiffness matrices corresponding to the interface degrees of freedom with the condensed stiffness matrices of the two parts to obtain the first iteration global stiffness matrix of the weld region. w K (1) ;

[0040] S435: Calculate the deviation correction Δ based on the equilibrium equation. w V (1) =-( w K (1) ) -1 Φ( w V (1) ), where Φ( w V)= w K( w V)· w V-( A K A V+ B K B V) represents the unbalanced force during the iterative process; based on this, the second deviation approximate solution is obtained. w V (2) = w V (1) +Δ w V (1) ;

[0041] S436: Calculate the magnitude of the unbalanced force. If it does not meet the allowable error range, repeat steps S432 to S435 until Φ( w V) Small enough.

[0042] Preferably, the expression for the overall assembly deviation of the storage tank is:

[0043] as V = [ A1 V T w V T B1 V T ] T

[0044] in, A1 V represents the assembly deviation vector of the node corresponding to the elastic zone of part A. w V represents the assembly deviation vector of the welded area nodes. B1 V represents the assembly deviation vector of the node corresponding to the elastic zone of part B.

[0045] Because the present invention adopts the above technical solution, it has the following beneficial effects:

[0046] This invention closely integrates the deformation and deviation distribution characteristics during the assembly process of ultra-large, reinforced, non-uniform structures. Field measurements show that the deviations of the assembled heavy rocket tube section structure are distributed in a spatial network. However, current assembly deviation analysis models are mainly used for "point-to-point" deviation models of rigid structures and "face-to-face" transfer models of overall flexible structures, which are mainly based on deformation. These models cannot be applied to the prediction and tracing of ultra-large, reinforced, locally rigid, and overall flexible network deviations.

[0047] This invention addresses the problem of weld deviations in ultra-large reinforced structures exhibiting a network distribution along the weld seam. It proposes a non-uniform stiffness condensation model for the ultra-large reinforced region, using the elastic-plastic interface to describe the non-uniform stiffness characteristics of the elastic region. Based on the superposition of stiffness in the plastic and elastic regions and the compatibility of interface deformation, and by introducing the welding stress field of the long-range welding process, an analytical model for weld deviations in ultra-large structures under the coupled influence of geometric nonlinearity and welding deformation is established, enabling deviation prediction and analysis during the welding process of ultra-large structures. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the assembly process of the ultra-large structure according to an embodiment of the present invention;

[0049] Figure 2 This is a schematic diagram of long-range welding stress prediction according to an embodiment of the present invention;

[0050] Figure 3 This is a flowchart illustrating the iterative solution process for welding deviations in ultra-large structures according to an embodiment of the present invention. Detailed Implementation

[0051] The following is based on the attached diagram. Figures 1-3 The present invention provides preferred embodiments and describes them in detail to enable a better understanding of the functions and features of the present invention.

[0052] Please see Figures 1-3 An assembly deviation analysis method for non-uniform condensation of ultra-large structural stiffness according to an embodiment of the present invention includes the following steps:

[0053] S1: Divide the super-large structure into a plastic region 2 and a super-large reinforced elastic region 1. The plastic region 2 is adjacent to the weld of the super-large structure, while the super-large reinforced elastic region 1 is far away from the weld.

[0054] Based on the process parameters of friction stir welding, the stress distribution of the ultra-large structure welding was preliminarily predicted through finite element analysis. The stress concentration distribution area at the weld is the plastic region 2, and the area away from the weld is the ultra-large reinforced elastic region 1.

[0055] S2: Construct a non-uniform condensation model for the stiffness of ultra-large structures that is suitable for the network-like concentrated distribution characteristics of assembly deviations in ultra-large structures.

[0056] The construction of a non-uniform condensation model for ultra-large structural stiffness includes the following steps:

[0057] S21: Based on the theory of continuum mechanics, derive the nonlinear stiffness matrix of a single element for ultra-large reinforced regions, denoted as K. (1) ; its specific form is:

[0058]

[0059] Among them B NL This is the nonlinear strain matrix related to the structural configuration.

[0060] S22: For the nonlinear stiffness matrix K of the element (1) Divide the space into blocks according to the interface degree of freedom r and the first internal degree of freedom s, that is:

[0061]

[0062] Among them, K ss (1) K represents the stiffness matrix corresponding to the first internal degree of freedom. rr (1) K represents the stiffness matrix corresponding to the interface degrees of freedom. sr (1) With K rs (1) This represents the block stiffness matrix that is related to both the first internal degree of freedom and the interface degree of freedom.

[0063] S23: The interface degree of freedom r is used to characterize the first internal degree of freedom s. Stiffness reduction is performed on the stiffness matrix that is only related to the first internal degree of freedom. For the quasi-static assembly process, static reduction theory can be used to form a reduced stiffness matrix for ultra-large stiffened structures.

[0064]

[0065] Among them, K rr (1) K rs (1) K ss (1) K sr (1) All are related to the configuration of the elastic region and participate in the iterative calculation of the assembly process.

[0066] S3: Construct a stiffness model under geometric nonlinearity for the weld region, and combine the stiffness model with the condensed stiffness matrix of the super-large stiffened structure to establish an overall stiffness model of the super-large structure described by the weld region and its interface.

[0067] The steps involved in establishing the overall stiffness model of a super-large structure are as follows:

[0068] S31: To address the geometric nonlinear deformation characteristics of the weld region during the assembly process, a stiffness matrix K for the weld region related to the structural configuration is established based on large deformation theory. (2) In this embodiment, the weld region is discretized using the same isoparametric hexahedral elements as the elastic region, and a stiffness matrix K capable of incorporating nonlinear geometric deformations of the structure is derived. (2) ;

[0069] S32: The stiffness matrix K of the weld region (2) Divide into blocks according to the interface degree of freedom r and the second internal degree of freedom m;

[0070] S33: Combine the stiffness matrix of the weld region with the condensed stiffness matrix of the super-large stiffened structure to establish the overall stiffness matrix K of the super-large structure:

[0071]

[0072] Among them, K mm (2) K represents the stiffness matrix corresponding to the second internal degree of freedom. rr (2) K represents the stiffness matrix corresponding to the interface degrees of freedom. mr (2) With K rm (2) This represents the block stiffness matrix that is related to both the second internal degree of freedom and the interface degree of freedom.

[0073] It can be seen that the degrees of freedom in the weld area and the stiffened elastic area are related by m << s. Therefore, the dimension of the overall stiffness matrix K of the super-large structure established by stiffness condensation is greatly reduced, which is beneficial to improving the calculation efficiency of the subsequent assembly process.

[0074] S4: Considering the influence of welding deformation during the welding process, a welding stress field is introduced. Based on the deformation coordination relationship before and after assembly in plastic region 2, a welding deviation analysis model is established. Solve the welding deviation of the ultra-large structure to realize the prediction and analysis of the assembly deviation of the ultra-large reinforced structure.

[0075] The establishment of a welding deviation analysis model includes the following steps:

[0076] S41: Establish a welding stress field characterization method for long-range friction stir welding of ultra-large structures to provide welding input for assembly deviation analysis of ultra-large structures;

[0077] Welding stress field characterization: By establishing a local small model 3 of the weld, thermo-elastic-plastic analysis is performed on the local small model 3 of the weld. Based on the welding stress mapping relationship from the local small model 3 of the weld to the long-range weld model 4, stress prediction of the long-range welding process is realized.

[0078] S42: Based on the deformation coordination relationship before and after assembly in the weld area, a nonlinear equilibrium equation for the assembly process is constructed to form an assembly deviation analysis model for ultra-large structures.

[0079] The nonlinear equilibrium equation for the assembly process is:

[0080]

[0081] in w K, A K and B K represents the stiffness matrix of the weld region of the assembly and the part after the superposition of condensation and stiffness. w V. A V and B V represents the deviation corresponding to the degree of freedom in the weld area. In this embodiment, the initial deviation of part A is the bending deviation, and part B is a standard part, i.e. B V = 0.

[0082] S43: Iteratively solve the nonlinear equilibrium equation of the assembly process to obtain the overall assembly deviation of the ultra-large structure;

[0083] The iterative solution of the nonlinear equilibrium equation includes the following steps:

[0084] S431: Solve for the stiffness matrix of a large structure under small deformation, and superimpose the stiffness matrix of the weld region. w K (0) Condensation stiffness matrix of reinforced region and Solving the equilibrium equations yields the first approximate solution for the weld zone deviation. w V (1) ;

[0085] S432: First approximate solution based on weld zone deviation w V (1) Given the interface displacement boundary conditions, the inverse solution approximates the deviation of the condensed region of the part. A1 V (1) and B1 V (1) ;

[0086] S433: Approximate solution based on the deviation of the condensed region of the part A1 V (1) , B1 V (1) Calculate the stiffness matrix of the elastic region of the part. A1 K(1) , B1 K (1) Based on this, a second condensation process is performed to obtain the condensation stiffness matrix of the part. and

[0087] S434: First approximate solution based on weld zone deviation w V (1) Calculate the stiffness matrix of the weld region, and then superimpose the stiffness matrices corresponding to the interface degrees of freedom with the condensed stiffness matrices of the two parts to obtain the first iteration global stiffness matrix of the weld region. w K (1) ;

[0088] S435: Calculate the deviation correction Δ based on the equilibrium equation. w V (1) =-( w K (1) ) -1 Φ( w V (1) ), where Φ( w V)= w K( w V)· w V-( A K A V+ B K B V) represents the unbalanced force during the iterative process; based on this, the second deviation approximate solution is obtained. w V (2) = w V (1) +Δ w V (1) ;

[0089] S436: Calculate the magnitude of the unbalanced force. If it does not meet the allowable error range, repeat steps S432 to S435 until Φ( w V) Small enough.

[0090] S44: Treat the current assembly as a new part and re-execute S41 with another part that has an assembly relationship until the entire assembly is completed, thereby obtaining the overall assembly deviation V of the storage tank of the assembly after the ultra-large structure is assembled. as .

[0091] The expression for the overall assembly deviation of the storage tank is:

[0092] as V = [ A1 V T w V T B1 V T ]T

[0093] in, A1 V represents the assembly deviation vector of the node corresponding to the elastic zone of part A. w V represents the assembly deviation vector of the welded area nodes. B1 V represents the assembly deviation vector of the node corresponding to the elastic zone of part B.

[0094] The assembly deviation analysis method for non-uniform condensation of stiffness in ultra-large structures, as described in this invention, can effectively predict assembly deviations of ultra-large structures with a network-like concentrated distribution, and significantly improves the modeling and calculation efficiency of ultra-large stiffened non-uniform structures. Through deviation prediction and analysis of the hierarchical assembly process of ultra-large structures, a theoretical basis is provided for further compensation and control of assembly deviations in ultra-large structures.

[0095] The present invention has been described in detail above with reference to the accompanying drawings and embodiments. Those skilled in the art can make various modifications to the present invention based on the above description. Therefore, certain details in the embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention shall be defined by the appended claims.

Claims

1. A method for analyzing assembly deviations in ultra-large structure stiffness non-uniform condensation, comprising the following steps: S1: The super-large structure is divided into a plastic region and a super-large reinforced elastic region. The plastic region is the weld of the super-large structure and its adjacent area, and the super-large reinforced elastic region is far away from the weld. S2: Construct a non-uniform condensation model for the stiffness of ultra-large structures that is suitable for the network-like concentrated distribution characteristics of assembly deviations in ultra-large structures. S3: Construct a stiffness model under geometric nonlinearity for the weld region, and combine the stiffness model with the condensed stiffness matrix of the super-large stiffened structure to establish an overall stiffness model of the super-large structure described by the weld region and its interface. S4: Considering the influence of welding deformation during the welding process, a welding stress field is introduced, and a welding deviation analysis model is established based on the deformation coordination relationship before and after assembly in the plastic region; the welding deviation of the ultra-large structure is solved to realize the prediction and analysis of the assembly deviation of the ultra-large stiffened structure. in, The establishment of the welding deviation analysis model includes the following steps: S41: Establish a welding stress field characterization method for the long-range friction stir welding process of the super-large structure to provide welding input for the assembly deviation analysis of the super-large structure; S42: Based on the deformation coordination relationship of the weld area before and after assembly, a nonlinear equilibrium equation for the assembly process is constructed to form an assembly deviation analysis model for ultra-large structures; the nonlinear equilibrium equation for the assembly process is: ,in, , and These are the stiffness matrices of the assembly and the weld seam region of the parts, respectively, after the superposition of condensation and stiffness. , and These represent the corresponding deviations of the degrees of freedom in the weld area; S43: Iteratively solve the nonlinear equilibrium equation of the assembly process to obtain the overall assembly deviation of the ultra-large structure; S44: Treat the current assembly as a new part and re-execute S41 with another part that has an assembly relationship until the entire assembly is completed, thereby obtaining the overall assembly deviation of the storage tank of the assembly after the ultra-large structure is assembled. .

2. The assembly deviation analysis method for non-uniform condensation of ultra-large structural stiffness according to claim 1, characterized in that, In step S1: Based on the process parameters of friction stir welding, the stress distribution of the super-large structure welded assembly is preliminarily predicted through finite element analysis. The stress concentration distribution area at the weld is the plastic region, and the area away from the weld is the super-large reinforced elastic region.

3. The assembly deviation analysis method for non-uniform condensation of ultra-large structural stiffness according to claim 2, characterized in that, The construction of the super-large structural stiffness non-uniform condensation model includes the following steps: S21: Based on the theory of continuum mechanics, a single-element nonlinear stiffness matrix is ​​derived for the aforementioned ultra-large reinforced region, denoted as... ; S22: For the nonlinear stiffness matrix of the element Based on interface degrees of freedom With the first internal degree of freedom Blocking, that is: ； in, This represents the stiffness matrix corresponding to the first internal degree of freedom. This represents the stiffness matrix corresponding to the interface degrees of freedom. and This represents the block stiffness matrix that is related to both the first internal degree of freedom and the interface degree of freedom. S23: Employing the aforementioned interface degrees of freedom Characterizing the first internal degree of freedom Stiffness condensation is performed on the stiffness matrix that is only related to the first internal degree of freedom to form a condensed stiffness matrix of the ultra-large stiffened structure. : ； in, , , , All are related to the configuration of the elastic region and participate in the iterative calculation of the assembly process.

4. The assembly deviation analysis method for non-uniform condensation of ultra-large structural stiffness according to claim 3, characterized in that, The establishment of the overall stiffness model of the ultra-large structure includes the following steps: S31: Introducing the geometric nonlinear deformation characteristics of the assembly process into the weld region, a weld region stiffness matrix related to the structural configuration is established based on large deformation theory. ; S32: The stiffness matrix of the weld area... According to the interface degrees of freedom With the second internal degree of freedom Blocking; S33: Combine the stiffness matrix of the weld region with the condensed stiffness matrix of the super-large stiffened structure to establish the overall stiffness matrix of the super-large structure. : ； in, This represents the stiffness matrix corresponding to the second internal degree of freedom. This represents the stiffness matrix corresponding to the interface degrees of freedom. and This represents the block stiffness matrix that is related to both the second internal degree of freedom and the interface degree of freedom.

5. The assembly deviation analysis method for non-uniform condensation of ultra-large structural stiffness according to claim 1, characterized in that, The welding stress field characterization is achieved by establishing a local small model of the weld, performing thermo-elastic-plastic analysis on the local small model of the weld, and realizing the welding stress prediction of the long-range welding process based on the welding stress mapping relationship from the local small model of the weld to the long-range weld model.

6. The assembly deviation analysis method for non-uniform condensation of ultra-large structural stiffness according to claim 1, characterized in that, The iterative solution of the nonlinear equilibrium equation includes the following steps: S431: Solve for the stiffness matrix of the aforementioned ultra-large structure under small deformation, and superimpose the stiffness matrix of the weld region. Condensation stiffness matrix of reinforced region and Solving the equilibrium equations yields the first approximate solution for the weld zone deviation. ; S432: The first approximate solution based on the weld area deviation Given the interface displacement boundary conditions, the inverse solution approximates the deviation of the condensed region of the part. and ; S433: Based on the approximate solution of the deviation in the condensed region of the part. , Calculate the stiffness matrix of the elastic region of the part. , Based on this, a second condensation process is performed to obtain the condensation stiffness matrix of the part. and ; S434: Based on the first approximate solution of the weld zone deviation Calculate the stiffness matrix of the weld region, and then superimpose the stiffness matrices corresponding to the interface degrees of freedom with the condensed stiffness matrices of the two parts to obtain the first iteration global stiffness matrix of the weld region. ; S435: Calculate the deviation correction amount based on the equilibrium equation. ,in The unbalanced force in the iterative process; based on this, the second deviation approximate solution is obtained. ; S436: Calculate the magnitude of the unbalanced force. If it does not meet the allowable error range, repeat steps S432 to S435 until... Sufficiently small.

7. The assembly deviation analysis method for non-uniform condensation of ultra-large structural stiffness according to claim 1, characterized in that, The expression for the overall assembly deviation of the storage tank is: ； in, This represents the assembly deviation vector of the node corresponding to the elastic zone of part A. This represents the assembly deviation vector of the welded area nodes. This represents the assembly deviation vector of the node corresponding to the elastic zone of part B.

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