Finite element analogue simulation method of plug-in type quick-release wing separation surface connecting structure

Abstract

The invention discloses a plug-in type quick-release wing separation surface connection structure finite element analogue simulation method, which comprises the following steps of: establishing a model for plug-in beams on two sides of a wing separation surface by adopting a Bar unit, establishing a model for a support structure of the plug-in beams by adopting a finite element unit, and connecting the plug-in beams and the support structure through multipoint constraint unit matching nodes. Through one-dimensional simplified simulation of the insertion beam, setting of a complex force transmission relation under the insertion action is avoided, meanwhile, the requirement for main torque transmission of the wing is met, and the problems that in the prior art, stress of the insertion beam at the separation face cannot be accurately calculated, contact setting is complex, and calculation efficiency is low are solved by combining the classical beam bending theory.

Description

Technical Field

[0001] The present invention relates to the field of aircraft structure finite element modeling, and particularly to a finite element simulation method for a plug-in and quick-release wing separation surface connection structure. Background Art

[0002] With the rapid development of the low-altitude economy, the market has higher and higher requirements for the fast and low-cost transportation and delivery of aircraft, which has given rise to a series of quick-release aircraft. The most common ones are quick-release wings and quick-release tails, because they can minimize the transportation space requirements when delivering the whole aircraft. As shown in Figure 1-2 a plug-in beam type quick-release wing, which includes a central wing and outer wings connected to both ends of the central wing. The central wing and the outer wings are docked through a plug-in beam at the separation surface. The overall bending moment and shear force of the outer wings are transmitted to the central wing through a single path of the plug-in beam. Once the strength of the plug-in beam is insufficient, it will seriously affect the safety of the aircraft. The quick-release requirement often interrupts the force transmission continuity in the span direction of the wing, bringing great challenges to the strength design of the connection structure at the quick-release separation surface. Currently, the internal force analysis of the structure is mainly carried out through finite element simulation. In the finite element simulation, the accuracy of the internal force analysis results is affected by the finite element model. When the force transmission characteristics simulated by the finite element model are inconsistent with the force transmission characteristics of the actual structure, the obtained internal force results will deviate from the true value. If the strength assessment is based on the distorted internal force results, there will be great potential safety hazards.

[0003] Currently, there are usually two modeling methods for the finite element simulation of the plug-in beam structure: First, the two pipe beam structures in plug-in fit are simulated by shell elements, and the elements in the plug-in coincidence plane are co-noded to simulate the interaction relationship between the two pipe beams. Since co-noding will introduce deformation restrictions that do not exist along the axial direction of the pipe beam, this restriction will cause untrue local eccentric bending moments on the compression side and the tension side of the pipe beam wall when the two pipe beams with different outer diameters transmit bending moments, and ultimately lead to the stress at the separation surface of the pipe beam wall being greater than the true state. Second, the two pipe beam structures are simulated by shell elements, and a contact action is set between the plug-in coincidence planes. This method can obtain relatively accurate results, but this method will introduce contact nonlinearity into the model. If the contact properties are set improperly, it usually causes problems of difficult calculation convergence, which will greatly increase the model debugging time and occupy more computing resources. Summary of the Invention

[0004] In view of the above technical problems, the present invention aims to provide a finite element simulation method for the plug-in and quick-release wing separation surface connection structure. Through this method, without introducing contact non-linearity, by combining the use of common basic elements, the force transmission relationship of the plug-in and quick-release wing separation surface connection structure can be accurately simulated in a simple and efficient manner, so as to accurately calculate the bending stress of the plug-in connection structure, while greatly reducing the modeling complexity and significantly improving the calculation efficiency and accuracy.

[0005] In view of achieving the above objectives, the present application provides a finite element simulation method for a plug-in and quick-release wing separation surface connection structure. The connection structure includes a plug-in beam and a support structure of the plug-in beam, and the method includes the steps of: S1. Establish a finite element model of each part of the wing; S2. Establish the connection relationship of each part; S3. Analyze and calculate; The step S1 of establishing the finite element model of each part of the wing includes: the plug-in beam is modeled using Bar elements, and the plug-in beam is divided into three segments and attributes are assigned respectively. That is, the overlapping part of the plug-in beam is assigned attributes according to the superimposed cross-sectional dimensions and equivalent material, and the non-overlapping parts are assigned attributes according to the cross-sectional dimensions and materials of the two plug-in beams respectively; the support structure is modeled according to the finite element unit and attributes are assigned according to the actual state of the structure.

[0006] The plug-in beam is defined according to the plug-in fit relationship, including an inner plug-in beam and an outer plug-in beam, and one end of the inner plug-in beam is inserted into the outer plug-in beam.

[0007] The Bar element is a one-dimensional simple beam element used to describe straight beam members with a constant cross-section of different geometric shapes. It has two nodes, and each node has 6 degrees of freedom, namely the translation and rotation in the three spatial directions of X, Y, and Z, and can simulate the lateral bending, shear, and axial deformation of the beam.

[0008] The definition of the equivalent material of the overlapping part of the plug-in beam: The overlapping part of the plug-in beam is integrally simulated as an isotropic material, and its elastic modulus Ee and shear modulus Ge need to be given respectively according to the equivalent principles of the bending stiffness and shear stiffness of the plug-in beam cross-section. The specific calculation formulas are as follows: ; ; In the formula: is the elastic modulus of the material used for the inner plug-in beam along the axial direction of the beam, with the unit of MPa; is the elastic modulus of the material used for the outer plug-in beam along the axial direction of the beam, with the unit of MPa; is the moment of inertia of the inner plug-in beam, with the unit of mm^4; is the moment of inertia of the outer plug-in beam, with the unit of mm^4; is the shear modulus of the material used for the inner plug-in beam within the beam cross-section, with the unit of MPa; is the shear modulus of the material used for the outer plug-in beam within the beam cross-section, with the unit of MPa; is the cross-sectional area of the inner plug-in beam, with the unit of mm^2; is the cross-sectional area of the outer plug-in beam, with the unit of mm^2.

[0009] In finite element simulation, the accuracy of the structural internal force analysis results is affected by the finite element model. When the force transmission characteristics simulated by the finite element model are inconsistent with those of the actual structure, the obtained internal force results will deviate from the true values. If strength assessment is carried out based on the distorted internal force results, there will be significant potential safety hazards. For the plug-in type quick-disassembly wing separation surface connection structure, the force transmission characteristics of the underconstrained statically indeterminate structure it exhibits are difficult to simulate during the finite element modeling process. Because for an underconstrained structure, finite element simulation will result in problems that cannot be calculated (with rigid body displacements), and mathematically speaking, this model will have an infinite number of solutions. Although the existing technology can make the model able to calculate and obtain a unique solution by setting contact constraints (normal hard contact and tangential friction constraints) in the overlapping part of the two plug-in beams, this method will introduce non-linear factors into the model, resulting in difficult convergence of the model calculation and a significant reduction in calculation efficiency. In this implementation plan, first, by simplifying the plug-in beam into a one-dimensional beam element, it is ensured that the stiffness of the model is consistent with the actual stiffness of the structure, and the overall force transmission characteristics of the wing separation surface connection structure are not changed, and non-linear factors are not introduced.

[0010] In another implementation plan, the step S2 of establishing the connection relationships of each part includes: The plug-in beams are connected through nodes at the separation surface to simplify the simulation of the interaction relationships of the plug-ins; the plug-in beams and their support structures are connected through multi-point constraint elements to coordinate the connection relationships from single nodes to multi-nodes.

[0011] In this implementation plan, by connecting through nodes at the separation surface of the plug-in beam, the underconstrained degrees of freedom in the axial direction of the plug-in beam are eliminated, turning the underconstrained statically indeterminate structure model into a statically determinate structure, ensuring that the model can be calculated and a unique solution can be obtained.

[0012] In another implementation plan, the step S3 of analysis and calculation includes: Load and solve the overall wing model, extract the bending moment of the nodes of the plug-in beam at the separation surface, and calculate the bending stress of the plug-in beam. The calculation formula is as follows: , In the formula: σ is the bending stress of the plug-in beam at the separation surface, with the unit of MPa; M is the bending moment of the plug-in beam at the separation surface, with the unit of N·mm; I is the sectional moment of inertia of the plug-in beam at the separation surface, with the unit of mm^4; y is the distance from the centroid of the cross-section of the plug-in beam at the separation surface to the stress calculation point, with the unit of mm.

[0013] In this implementation scheme, based on the above finite element model, the plug-in beam mainly transfers the overall bending moment, and its force form can be simplified to pure bending. Therefore, the stress value at any position on the cross-section can be obtained by using the pure bending theory formula, and the calculation is simple.

[0014] In another implementation scheme, the plug-in beam is any one of the plug-in forms of a circular tube beam and a circular tube beam, a circular shaft beam and a circular tube beam, a square tube beam and a square tube beam, a channel beam and a channel beam, or a plug-in beam with other cross-sectional forms.

[0015] In another implementation scheme, the support structure includes main beams, main beam joints, butt ribs, and butt rib joints that respectively support two plug-in beams; or other forms of support structures.

[0016] In another implementation scheme, when establishing the finite element models of each part in step S1, the main beam joint is simplified to an RBE2 element, which is only used to simulate the connection relationship; the main beam, butt rib, and butt rib joint are respectively modeled according to two-dimensional shell elements. The RBE2 is a rigid multi-point constraint.

[0017] In another implementation scheme, when establishing the connection relationships of each part in step S2, the main beam is directly connected to the butt rib by sharing nodes; for the plug-in beams on both sides of the separation surface, one end connected to the main beam is coordinated from a single node to multiple nodes through an RBE2 element, and the other end is coordinated from a single node to multiple nodes through an RBE3 element with the butt rib joint. The RBE3 is a flexible multi-point constraint.

[0018] The beneficial effects of the present invention: Without introducing contact nonlinearity, through the combined use of common basic elements, it can accurately simulate the force transmission relationship of the plug-in and quickly detachable wing separation surface connection structure in a simple and efficient manner, so as to accurately calculate the bending stress of the plug-in beam structure, while greatly reducing the modeling complexity and significantly improving the calculation efficiency. Description of the Drawings

[0019] Appendix Figure 1 is a schematic diagram of a plug-in and quick-release wing structure; Appendix Figure 2 is for the Figure 1 internal structure schematic diagram after removing the skin from the A part structure in Appendix Figure 3 is the overall schematic diagram of the finite element model of Example 1; Appendix Figure 4 is the partial schematic diagram of the finite element model of Example 1; Appendix Figure 5 is the schematic diagram of the bending moment value output at the separation surface of the plug-in beam in Example 1 under the finite element model; Appendix Figure 6 is the schematic diagram of the bending moment value output at the separation surface of the plug-in beam in Example 2 under the finite element model; Appendix Figure 7 is the schematic diagram of the finite element model of the plug-in beam in Comparative Example 1 simulated by two-dimensional shell elements and the plug-in overlapping area simulated by the co-node method; Appendix Figure 8 is the stress nephogram of the plug-in beam in Comparative Example 1 simulated by two-dimensional shell elements and the plug-in overlapping area simulated by the co-node method; Appendix Figure 9 is the stress distribution curve along the length direction of the outer wing tube beam obtained by simulating the plug-in beam in Comparative Example 1 by two-dimensional shell elements and the plug-in overlapping area by the co-node method; Appendix Figure 10 is the stress nephogram of the plug-in beam in Comparative Example 2 simulated by two-dimensional shell elements and the plug-in overlapping area simulated by the contact nonlinear method; Appendix Figure 11 is the stress distribution curve along the length direction of the outer wing tube beam obtained by simulating the plug-in beam in Comparative Example 2 by two-dimensional shell elements and the plug-in overlapping area by the contact nonlinear method; Appendix Figure 12 is the stress nephogram of the plug-in beam in Comparative Example 3 simulated by two-dimensional shell elements and the plug-in overlapping area simulated by the contact nonlinear method; Wherein: 1 - central wing main beam; 2 - central wing main beam joint; 3 - central wing tube beam; 4 - central wing docking rib joint; 5 - central wing docking rib; 6 - outer wing docking rib; 7 - outer wing tube beam; 8 - outer wing docking rib joint; 9 - outer wing main beam joint; 10 - outer wing main beam. Specific implementation mode

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0021] Embodiment 1

[0022] For the plug-in type quick-release wing separation surface connection structure in this embodiment, refer to the attached Figure 1-2 , which includes a plug-in beam and a support structure.

[0023] The plug-in beam is formed by plugging a circular tube beam of the same material into another circular tube beam, that is, the central wing tube beam 3 is inserted into the outer wing tube beam 7. The outer diameter of the central wing tube beam 3 is 34 mm, the inner diameter is 30 mm, the outer diameter of the outer wing tube beam 7 is 30 mm, and the inner diameter is 26 mm.

[0024] The support structure includes a main beam, a main beam joint, a buttress rib, and a buttress rib joint. The main beam includes a central wing main beam 1 and an outer wing main beam 10. The main beam joint includes a central wing main beam joint 2 and an outer wing main beam joint 9. The buttress rib includes a central wing buttress rib 5 and an outer wing buttress rib 6. The buttress rib joint includes a central wing buttress rib joint 4 and an outer wing buttress rib joint 8. The central wing tube beam 3 is connected to the central wing main beam 1 through the central wing main beam joint 2 and is connected to the central wing buttress rib 5 through the central wing buttress rib joint 4. The outer wing tube beam 7 is connected to the outer wing main beam 10 through the outer wing main beam joint 9 and is connected to the outer wing buttress rib 6 through the outer wing buttress rib joint 8.

[0025] A finite element simulation method for a plug-in type quick-release wing separation surface connection structure includes the steps of: S1. Establish finite element models for each component of the wing, including: The plug-in beam is modeled using Bar elements, and the plug-in beam is divided into three segments and assigned properties respectively. That is, the overlapping part of the plug-in beam is assigned properties according to the superimposed cross-sectional dimensions and equivalent material, and the non-overlapping parts are assigned properties according to the respective cross-sectional dimensions and materials of the two plug-in beams. The support structure is modeled according to finite element units and assigned properties according to the actual thickness and material. Specifically, refer to the attached Figure 3 , the central wing tube beam 3 and the outer wing tube beam 7 are respectively modeled using Bar elements, and the overall of the central wing tube beam 3 and the outer wing tube beam 7 after plugging is divided into three segments and assigned properties respectively. The overlapping part is assigned properties according to the cross-sectional dimensions and equivalent material after the plugging of the central wing tube beam 3 and the outer wing tube beam 7, and the non-overlapping parts are assigned properties according to their respective cross-sectional dimensions and materials. According to the definition of the plugging and mating relationship of the plug-in beam, the outer wing tube beam 7 is the inner plug-in beam, and the central wing tube beam 3 is the outer plug-in beam.

[0026] The elastic modulus Ee and shear modulus Ge of the equivalent material of the overlapping part of the plug-in beam are calculated by the following two formulas: ; ; In the formula: is the elastic modulus of the material used for the inner plug-in beam along the axial direction of the beam, with the unit of MPa; is the elastic modulus of the material used for the outer plug-in beam along the axial direction of the beam, with the unit of MPa; is the moment of inertia of the cross-section of the inner plug-in beam, with the unit of mm^4; is the moment of inertia of the cross-section of the outer plug-in beam, with the unit of mm^4; is the shear modulus of the material used for the inner plug-in beam within the beam cross-section, with the unit of MPa; is the shear modulus of the material used for the outer plug-in beam within the beam cross-section, with the unit of MPa; is the cross-sectional area of the inner plug-in beam, with the unit of mm^2; is the cross-sectional area of the outer plug-in beam, with the unit of mm^2.

[0027] Since the inner plug-in beam and the outer plug-in beam are of the same material, E1 and E2 are the same, and G1 and G2 are the same, that is: Ee = E1 = E2; Ge = G1 = G2.

[0028] In addition, the main beam joint can be simplified to an RBE2 element only for simulating the connection relationship, that is, the central wing main beam joint 2 and the outer wing main beam joint 9 are simplified to RBE2 elements; the main beam, buttress, and buttress joint can be modeled as two-dimensional shell elements respectively, that is, the central wing main beam 1, outer wing main beam 10, central wing buttress 5, outer wing buttress 6, central wing buttress joint 4, and outer wing buttress joint 8 are modeled as two-dimensional shell elements respectively.

[0029] Furthermore, it further includes the steps: S2. Establish the connection relationships of each part, where: the plug-in beam is connected by nodes at the separation surface to simplify the simulation of the interaction relationship of plugging; the plug-in beam and its support structure are connected by multi-point constraint elements to coordinate the connection relationship from a single node to multiple nodes; Specifically, refer to Appendix Figure 3-4, connect the central wing pipe beam 3 and the outer wing pipe beam 7 at the separation surface through Node 1 to simplify the simulation of the interaction relationship of the insertion of the central wing pipe beam 3 and the outer wing pipe beam 7, and ensure the correct transfer of the overall shear force, torque and main bending moment of the wing; one end of the central wing pipe beam 3 connected to the central wing main beam 1 is coordinated by an RBE2 element for the connection from a single node to multiple nodes, and the other end is coordinated by an RBE3 element for the connection from a single node (Node 3) to multiple nodes with the central wing docking rib joint 4; one end of the outer wing pipe beam 7 connected to the outer wing main beam 10 is coordinated by an RBE2 element for the connection from a single node to multiple nodes, and the other end is coordinated by an RBE3 element for the connection from a single node (Node 2) to multiple nodes with the outer wing docking rib joint 8; In addition, the main beam and the docking rib are directly connected by common nodes. Specifically, the central wing main beam 1 and the central wing docking rib 5 are connected by common nodes, and the outer wing main beam 10 and the outer wing docking rib 6 are connected by common nodes.

[0030] Furthermore, it further includes the steps: S3. Calculation and analysis, including: loading and solving the overall wing model, extracting the nodal moment M of Node 1 at the separation surface of the inserted beam, calculating the bending stress of the inserted beam. Since the moment is the main influencing quantity, the beam pure bending theory formula is used to calculate the bending stress of the inserted beam, and the calculation formula is as follows: , In the formula: σ is the bending stress of the inserted beam at the separation surface, with the unit of MPa; M is the moment of the inserted beam at the separation surface, with the unit of N·mm; I is the sectional moment of inertia of the inserted beam at the separation surface, with the unit of mm^4, y is the distance from the centroid of the cross-section of the inserted beam at the separation surface to the stress calculation point, with the unit of mm, Among them, through the loading calculation of the overall model, the value of the moment M of the inserted beam at the separation surface can be found in Appendix Figure 5 , which is 581364 N·mm; The sectional moment of inertia and the distance from the centroid of the cross-section of the inserted beam at the separation surface to the stress calculation point can be calculated according to the parameters of the inserted beam, and the calculation formula is as follows: ; ; In the formula: D is the outer diameter of the outer wing pipe beam 7; d is the inner diameter of the outer wing pipe beam 7; Substitute the corresponding parameters of the outer wing pipe beam 7 into the formula, and calculate to get: I = 17329.02 mm^4, y = 15 mm.

[0031] Then, substitute M, I, y the corresponding values into the formula for bending stress, and the calculated bending stress of the plug-in beam at the separation surface is 503.23 MPa.

[0032] In addition, the calculation log of the simulation process under this model shows that the calculation time is 2 s.

[0033] Embodiment 2

[0034] The difference between this embodiment and Embodiment 1 is that in this embodiment, the plug-in beam is the plug-in of a square tube beam and a square tube beam. The cross-sectional height of the central wing tube beam is 34 mm, the width is 24 mm, the wall thickness is 2 mm, the cross-sectional height of the outer wing tube beam is 30 mm, the width is 20 mm, and the wall thickness is 2 mm.

[0035] A finite element simulation method for a plug-in type quick-release wing separation surface connection structure includes the steps of: S1. Establish finite element models of each component of the wing, including: the plug-in beam is modeled using Bar elements, and the plug-in beam is divided into three segments and assigned attributes respectively, that is, the overlapping part of the plug-in beam is assigned attributes according to the superimposed cross-sectional dimensions and equivalent material, and the non-overlapping parts are assigned attributes according to the cross-sectional dimensions and materials of the two plug-in beams respectively; the support structure is modeled according to finite element elements and assigned attributes according to the actual thickness and material; Specifically, the central wing tube beam 3 and the outer wing tube beam 7 are respectively modeled using Bar elements, and the whole after the central wing tube beam 3 and the outer wing tube beam 7 are plugged in is divided into three segments and assigned attributes respectively. The overlapping part is assigned attributes according to the cross-sectional dimensions and equivalent material after the superposition of the central wing tube beam 3 and the outer wing tube beam 7, and the non-overlapping parts are assigned attributes according to their respective cross-sectional dimensions and materials. Since the inner plug-in beam and the outer plug-in beam are made of the same material, have the same elastic modulus, and the same shear modulus, the elastic modulus Ee and shear modulus Ge of the equivalent material are equal to the elastic modulus and shear modulus of the two plug-in beams.

[0036] In addition, the main beam joint can be simplified to an RBE2 element and only used to simulate the connection relationship, that is, the central wing main beam joint 2 and the outer wing main beam joint 9 are simplified to RBE2 elements; the main beam, butt joint rib, and butt joint rib joint can be respectively modeled according to two-dimensional shell elements, that is, the central wing main beam 1, the outer wing main beam 10, the central wing butt joint rib 5, the outer wing butt joint rib 6, the central wing butt joint rib joint 4, and the outer wing butt joint rib joint 8 are respectively modeled according to two-dimensional shell elements.

[0037] Furthermore, it further includes the steps of: S2. Establish the connection relationships of each component, where: the plug-in beams are connected through nodes at the separation surface to simplify the interaction relationship of the simulated plug-in; the plug-in beams and their support structures are connected through multi-point constraint units to coordinate the connection relationship from single-node to multi-node; Specifically, connect the central wing tube beam 3 and the outer wing tube beam 7 through node one at the separation surface to simplify the interaction relationship of the simulated plug-in between the central wing tube beam 3 and the outer wing tube beam 7, and ensure the correct transmission of the overall shear force, torque and main bending moment of the wing; one end of the central wing tube beam 3 connected to the central wing main beam 1 coordinates the connection from single-node to multi-node through the RBE2 unit, and the other end coordinates the connection from single-node (node three) to multi-node with the central wing docking rib joint 4 through the RBE3; one end of the outer wing tube beam 7 connected to the outer wing main beam 10 coordinates the connection from single-node to multi-node through the RBE2 unit, and the other end coordinates the connection from single-node (node two) to multi-node with the outer wing docking rib joint 8 through the RBE3; In addition, the main beam and the docking rib are directly connected by co-nodes. Specifically, the central wing main beam 1 and the central wing docking rib 5 are connected by co-nodes, and the outer wing main beam 10 and the outer wing docking rib 6 are connected by co-nodes.

[0038] Furthermore, it further includes the steps: S3. Calculation and analysis, including: loading and solving the overall wing model, extracting the node moment M of node one at the separation surface of the plug-in beam, and calculating the bending stress of the plug-in beam. The calculation formula is as follows: , In the formula: σ is the bending stress of the plug-in beam at the separation surface, with the unit of MPa; M is the moment of the plug-in beam at the separation surface, with the unit of N·mm; I is the sectional moment of inertia of the plug-in beam at the separation surface, with the unit of mm^4; y is the distance from the centroid of the cross-section of the plug-in beam at the separation surface to the stress calculation point, with the unit of mm; Among them, the moment M value of the plug-in beam at the separation surface can be referred to in Appendix Figure 6 , and the value is 609812 N·mm; The sectional moment of inertia and the distance from the centroid of the cross-section of the plug-in beam at the separation surface to the stress calculation point can be calculated according to the parameters of the plug-in beam. The calculation formula is as follows: ; ; In the formula: b1 is the outer wall width of the cross-section of the outer wing tube beam 7; h1 is the outer wall height of the cross-section of the outer wing tube beam 7; b2 is the inner wall width of the cross-section of the outer wing tube beam 7; h2 is the inner wall height of the cross-section of the outer wing tube beam 7; Substitute the corresponding parameters of the outer wing tube beam 7 into the formula, and the calculation results are as follows: , .

[0039] Then substitute the above M, I, y corresponding values into the calculation formula of bending stress, and the bending stress of the plug-in beam at the separation surface is calculated to be 424.17 MPa.

[0040] Comparative Example 1 The plug-in type quick-release wing separation surface connection structure in this comparative example is the same as that in Embodiment 1, the difference is that the first finite element simulation method described in the background technology is adopted. Refer to Appendix Figure 7 , simulate the plug-in beam with two-dimensional shell elements, and the elements in the plug-in coincidence area are connected by co-nodes; the specific steps are as follows: Step 1: Establish the finite element models of each component of the wing, including: establish the models of the plug-in beam and the support structure with shell elements, and assign properties according to the actual thickness and material; simplify the central wing main beam joint 2 and the outer wing main beam joint 9 into RBE2 elements; Step 2: Establish the connection relationships of each component, including: the elements of the plug-in beam in the plug-in coincidence area are connected by co-nodes, and the two main beams are respectively connected with the docking ribs by co-nodes; for the plug-in beams on both sides of the separation surface, the end connected to the main beam is connected by an RBE2 element, and the other end is connected to the docking rib joint by an RBE3 element; Step 3: Load and calculate the overall model. The stress nephogram of the outer wing tube beam 7 is as shown in Appendix Figure 8 , showing that the maximum stress at the separation surface is 650 MPa.

[0041] In addition, this comparative example also draws a stress distribution curve along the length direction of the outer wing tube beam 7 in combination with the stress nephogram. Refer to Appendix Figure 9 , specifically: starting from the separation surface of the outer wing tube beam 7, a total of 7 units are taken at equal intervals along the length direction of the outer wing tube beam outward (left), and the unit numbers are marked (the unit numbers decrease from 6 to 0 in sequence). The inner and outer surface stresses of the 7 units are plotted as curves. From this curve, it can be seen that the stress of the outer wing tube beam 7 within the range of units 0-5 basically satisfies the linear relationship, but there is a "bifurcation" phenomenon at unit 6, that is, the stress on the outer surface of the pipe wall suddenly increases, and the stress on the inner surface suddenly decreases. This bifurcation trend is caused by the superposition of the additional stress generated by the local bending moment introduced by the co-node method on the inner and outer surfaces of the pipe wall and the overall stress, which leads to an unrealistically large stress of the outer wing tube beam 7 at the separation surface.

[0042] Comparative Example 2 The plug-in quick-release wing separation surface connection structure in this comparative example is the same as that in Embodiment 1, except that the second finite element simulation method described in the background technology is adopted, that is, the plug-in beam is simulated by two-dimensional shell elements, and a contact action is set between the plug-in coincidence surfaces. The specific steps are as follows: Step 1: Establish a finite element model of each component of the wing, including: establishing a model of the plug-in beam and the support structure using shell elements, and assigning properties according to the actual thickness and material; simplifying the central wing main beam joint 2 and the outer wing main beam joint 9 into RBE2 elements; Step 2: Establish the connection relationship of each part, including: connecting the two main beams to the docking ribs by co-nodes respectively; connecting one end of the single-side plug-in beam of the separation surface to the main beam through an RBE2 element; connecting the other end to the docking rib joint through an RBE3 element; Step 3: Establish the contact action between the plug-in beam coincidence surfaces, including: 1) Define the contact surface: Select the outer surface of the shell element of the inner plug-in beam (outer wing pipe beam 7) as a unit set one, and select the inner surface of the shell element of the outer plug-in beam (central wing pipe beam 3) as another unit set two; 2) Define the contact property: Define the normal "hard contact" behavior, define the tangential "friction" behavior, and set the friction coefficient to 0.2; 3) Establish a contact pair: Define a "face-to-face" type contact pair, set unit set one as the master surface and unit set two as the slave surface; assign the contact property defined in step 2) to this contact pair; define a suitable adjustment tolerance according to the spatial position relationship between the two coincidence surfaces to complete the contact setting.

[0043] Step 4: Load and calculate the overall model.

[0044] In this comparative example, due to the introduction of contact nonlinearity, the calculation did not converge during the actual calculation process, and the model needed to be debugged multiple times. For example, it was necessary to change the size of the adjustment tolerance, replace the master and slave surfaces, etc., until the model finally reached a convergent state. The time-consuming degree of this debugging process is closely related to the experience level of the engineer.

[0045] The stress nephogram of the outer wing pipe beam 7 obtained when the final model reached the convergent state is as shown in the appendix Figure 10 It shows that the maximum stress at the separation surface is 498 MPa.

[0046] Combined with the stress nephogram in the appendix Figure 10 A stress distribution curve along the length direction of the outer wing pipe beam is plotted, see the appendix Figure 11 . It can be seen from this curve that the stress of the outer wing pipe beam 7 within the range of units 0-6 basically satisfies a linear relationship, and there is no "bifurcation" phenomenon that occurred in Comparative Example 1.

[0047] In addition, the calculation log of the simulation process after the convergence of this model shows that the calculation time is 69 s.

[0048] Comparative Example 3 The plug-in quick-release wing separation surface connection structure in this comparative example is the same as that in Embodiment 2, except that the second finite element simulation method described in the background technology is adopted, that is, the plug-in beam is simulated by two-dimensional shell elements, and a contact action is set between the plug-in coincidence surfaces. The specific steps are the same as those in Comparative Example 2.

[0049] In this comparative example, after the first modeling, the calculation did not converge. After subsequent repeated debugging, the model reached the convergence state.

[0050] The stress nephogram of the outer wing tube beam 7 when the model reaches the convergence state is shown in the appendix Figure 12 , showing that the maximum stress of the plug-in beam at the separation surface is 426.8 MPa.

[0051] Analyzing and comparing the simulation analysis results of the above Embodiments 1-2 and Comparative Examples 1-3, it can be seen that: 1) The bending stress values obtained in Embodiment 1 and Comparative Example 1 differ greatly. The bending stress value in Comparative Example 2 is in good agreement with that in Embodiment 1, verifying the effectiveness of the bending stress in Embodiment 1; thus indicating that the present invention eliminates the untrue stress generated by the local bending moment at the separation surface of the plug-in beam, and the obtained calculated value of the bending stress can meet the requirements of engineering design and use; 2) Compared with Comparative Example 2, Embodiment 1 avoids the occurrence of non-convergent calculation, thus avoiding the situation of repeatedly debugging the model and saving the modeling time; compared with the calculation time of Comparative Example 2 in Embodiment 1, the calculation efficiency is increased by 3350%; thus indicating that on the premise of ensuring the accurate calculation of the stress at the separation of the plug-in beam, the present invention greatly simplifies the modeling process and the calculation and debugging process, and greatly improves the calculation efficiency; 3) The bending stress in Embodiment 2 is in very good agreement with the bending stress in Comparative Example 3; thus indicating that the present invention can be adapted to the calculation of the bending stress at the separation surface of plug-in beams of any cross-sectional form.

[0052] The above are only specific embodiments of the present invention. The present invention is described in detail, and the unelaborated parts are conventional technologies. However, the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. The protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A finite element simulation method for a plug-in and quick-release wing separation surface connection structure, characterized in that The connection structure includes a plug-in beam and a support structure for the plug-in beam, and the method comprises the following steps: S1. Establish finite element models for each part; S2. Establish the connection relationships between each part; S3. Analyze and calculate; In step S1 of establishing finite element models for each part, it includes: The plug-in beam is modeled using Bar elements, and the plug-in beam is divided into three segments and attributes are assigned respectively. That is, for the overlapping part of the plug-in beam, attributes are assigned according to the superimposed cross-sectional dimensions and equivalent material, and for the non-overlapping parts, attributes are assigned according to the respective cross-sectional dimensions and materials of the two segments of the plug-in beam; The support structure is modeled according to finite element cells and attributes are assigned according to the actual state of the support structure.

2. The finite element simulation method of a plug-in and quick-release wing separation surface connection structure according to claim 1, characterized in that The equivalent material of the overlapping part of the plug-in beam needs to be defined as an isotropic material, and its elastic modulus Ee and shear modulus Ge need to be given according to the equivalent principles of the bending stiffness and shear stiffness of the plug-in beam cross-section respectively.

3. The finite element simulation method of a plug-in quick-release wing separation surface connection structure according to claim 1, characterized in that, In step S2 of establishing the connection relationships between each part, it includes: The plug-in beam is connected through nodes at the separation surface to simplify the simulation of the interaction relationship of plugging; The plug-in beam and its support structure are connected through multi-point constraint elements to coordinate the connection relationship from a single node to multiple nodes.

4. The finite element simulation method of a plug-in quick-release wing separation surface connection structure according to claim 3, characterized in that In step S3 of analyzing and calculating, it includes: Load and solve the overall wing model, extract the bending moment of the nodes at the separation surface of the plug-in beam, and calculate the bending stress of the plug-in beam. The calculation formula is as follows: ， In the formula: σ is the bending stress of the plug-in beam at the separation surface, with the unit of MPa; M is the bending moment of the plug-in beam at the separation surface, in N·mm; I is the sectional moment of inertia of the plug-in beam at the separation surface, with the unit of mm^4; y It is the distance from the centroid of the cross-section of the plug-in beam at the separation surface to the stress calculation point, with the unit of mm.

5. The finite element simulation method for the plug-in type quick-release wing separation surface connection structure according to claim 1, characterized in that The plug-in beam is any one of the plugging forms such as the plugging of a circular tube beam and a circular tube beam, the plugging of a circular shaft beam and a circular tube beam, the plugging of a square tube beam and a square tube beam, and the plugging of a channel beam and a channel beam.

6. The finite element simulation method of a plug-in type quick-release wing separation surface connection structure according to claim 3, characterized in that, The support structure includes a main beam, a main beam joint, a buttress rib, and a buttress rib joint that respectively support two plug-in beams.

7. The finite element simulation method of a plug-in quick-release wing separation surface connection structure according to claim 6, characterized in that, When establishing finite element models for each part in step S1, the main beam joint is simplified as an RBE2 element and is only used to simulate the connection relationship; The main beam, the buttress rib, and the buttress rib joint are respectively modeled according to two-dimensional shell elements.

8. The finite element simulation method of a plug-in type quick-release wing separation surface connection structure according to claim 6, characterized in that When establishing the connection relationships between each part in step S2, the main beam is directly co-noded with the buttress rib respectively; For the plug-in beams on both sides of the separation surface, one end connected to the main beam coordinates the connection from a single node to multiple nodes through an RBE2 element, and the other end coordinates the connection from a single node to multiple nodes with the buttress rib joint through an RBE3 element.

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