Finite element simulation method for plug-in quick-release wing separation surface connection structure

Abstract

The present invention discloses a finite element simulation method for a plug-in, quick-release wing separation surface connection structure. This method models the plug-in beams on either side of the wing separation surface using Bar units, and the supporting structure of the plug-in beams using finite element units. The plug-in beams and the supporting structure are connected by matching nodes using multi-point constraint units. Through a simplified one-dimensional simulation of the plug-in beams, the present invention avoids the complex force transmission relationship required for plug-in connection while meeting the wing's primary torque transmission requirements. Combined with classical beam bending theory, this method addresses existing issues such as the inability to accurately calculate the stress of the plug-in beam at the separation surface, complex contact configuration, and low computational efficiency.

Description

Technical Field

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

[0002] With the rapid development of the low-altitude economy, the market has increasingly high requirements for fast and low-cost transportation and delivery of aircraft, which has led to the emergence of a series of quick-detachable aircraft, the most common of which are quick-detachable wings and quick-detachable tails, because they can minimize the transportation space requirements when the aircraft is delivered. Figure 1 and attached Figure 2 The illustrated example is a splice-beam quick-detachable wing, comprising a central wing and outer wings connected at both ends of the central wing. The central wing and the outer wings are connected at the separation surface by a splice-beam. The overall bending moment and shear force of the outer wing are transmitted to the central wing through a single path, the splice-beam. Once the splice-beam is insufficiently strong, it will seriously affect the safety of the aircraft. The requirement for quick detachment often interrupts the continuity of force transmission in the span direction of the wing, posing a great challenge to the strength design of the connection structure at the quick-detachment separation surface. Currently, internal force analysis of the structure is mainly performed using finite element simulation. 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 the force transmission characteristics of the actual structure, the internal force results obtained will deviate from the true value. If strength assessment is performed based on distorted internal force results, there will be a major safety hazard.

[0003] Currently, finite element simulation of spliced ​​beam structures typically employs two modeling approaches: The first involves modeling the two spliced ​​beams using shell elements and treating the elements within the spliced ​​overlap surfaces as common nodes to simulate the interaction between the two beams. This common node introduces deformation constraints that don't exist along the beam axis. This constraint causes unrealistic local eccentric bending moments to form on both the compression and tension sides of the beam walls when the two beams, with different outer diameters, transmit bending moments. This ultimately results in greater stress on the beam wall at the separation surface than would be realistic. The second approach involves modeling the two beams using shell elements and establishing contact between the spliced ​​overlap surfaces. This method can yield relatively accurate results, but it introduces contact nonlinearity into the model. Improper contact properties often lead to computational convergence difficulties, significantly increasing model debugging time and consuming significant computational resources. Summary of the Invention

[0004] In response to the above technical problems, the present invention aims to provide a finite element simulation method for a plug-in quick-release wing separation surface connection structure. Through this method, the force transmission relationship of the plug-in quick-release wing separation surface connection structure can be accurately simulated in a concise and efficient manner by combining commonly used basic units without introducing contact nonlinearity, thereby accurately calculating 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 order to achieve the above objectives, the present application provides a finite element simulation method for a plug-in quick-release wing separation surface connection structure, wherein the connection structure includes a plug-in beam and a supporting structure of the plug-in beam, including the following steps:

[0006] S1. Establish finite element models of all wing parts;

[0007] S2. Establish the connection relationship between each part;

[0008] S3, analysis and calculation;

[0009] The step S1 establishes a finite element model of each wing part, including: the splice beam is modeled using Bar units, and the splice beam is divided into three sections and assigned attributes respectively, that is, the overlapping part of the splice beam is assigned attributes according to the cross-sectional dimensions and equivalent materials after superposition, and the non-overlapping part is assigned attributes according to the cross-sectional dimensions and materials of the two sections of the splice beam; the supporting structure is modeled using finite element units, and attributes are assigned according to the actual state of the structure.

[0010] The plug-in beam is defined according to a plug-in fitting relationship and includes 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.

[0011] The Bar unit is a one-dimensional simple beam unit used to describe straight beam components of constant cross-section with different geometric shapes. It has two nodes, each of which has six degrees of freedom, namely 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.

[0012] Definition of the equivalent material of the overlapping part of the spliced ​​beam: The overlapping part of the spliced ​​beam is simulated as an isotropic material, and its elastic modulus Ee and shear modulus Ge need to be given according to the equivalent principle of the bending stiffness and shear stiffness of the spliced ​​beam section, respectively. The specific calculation formula is as follows:

[0013] ;

[0014] ;

[0015] Where:

[0016] The elastic modulus of the material used for the internally connected beam along the axial direction of the beam, in MPa;

[0017] The elastic modulus of the material used for the external plug-in beam along the axial direction of the beam, in MPa;

[0018] is the section moment of inertia of the internally connected beam, in mm^4;

[0019] is the section moment of inertia of the external plug-in beam, unit is mm^4;

[0020] is the shear modulus of the material used for the internally connected beam within the beam section, in MPa;

[0021] is the shear modulus of the material used for the external plug-in beam within the beam section, in MPa;

[0022] is the cross-sectional area of ​​the internally connected beam, in mm^2;

[0023] is the cross-sectional area of ​​the external plug-in beam, in mm^2.

[0024] In finite element simulations, the accuracy of 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 resulting internal force results will deviate from the true values. Strength assessments based on distorted internal force results can pose significant safety risks. For plug-in quick-release wing separation surface connections, the force transmission characteristics of an underconstrained, statically indeterminate structure are difficult to simulate using finite element modeling. This is because finite element simulations of underconstrained structures can lead to uncalculated problems (with rigid body displacements), and mathematically, the model has an infinite number of solutions. While existing methods can achieve a unique solution by imposing contact constraints (normal hard contact and tangential friction constraints) on the overlapping portions of the two spliced ​​beams, this approach introduces nonlinear factors, making convergence difficult and significantly reducing computational efficiency. In this embodiment, the spliced ​​beams are first simplified into one-dimensional beam elements to ensure that the model's stiffness is consistent with the actual structure's stiffness, while also maintaining the overall force transmission characteristics of the wing separation surface connection structure and avoiding the introduction of nonlinear factors.

[0025] In another embodiment, the step S2 of establishing the connection relationship between the parts includes:

[0026] The splicing beams are connected by nodes at the separation surface to simplify the interaction relationship of the simulated splicing; the splicing beams and their supporting structures are connected by multi-point constraint units to coordinate the connection relationship from a single node to multiple nodes.

[0027] In this embodiment, by connecting the spliced ​​beams through nodes at their separation surfaces, the under-constrained degrees of freedom in the axial direction of the spliced ​​beams are eliminated, and the under-constrained statically indeterminate structure model is transformed into a statically determinate structure, ensuring that the model can be calculated and a unique solution can be obtained.

[0028] In another embodiment, the step S3 analysis and calculation includes:

[0029] The whole wing model is loaded and solved, the bending moment of the node of the splice beam at the separation surface is extracted, and the bending stress of the splice beam is calculated. The calculation formula is as follows:

[0030] ,

[0031] Where:

[0032] σ is the bending stress of the spliced ​​beam at the separation surface, unit: MPa;

[0033] M is the bending moment of the spliced ​​beam at the separation surface, in N·mm;

[0034] I is the section moment of inertia of the spliced ​​beam at the separation surface, in mm^4;

[0035] y is the distance from the cross-section centroid of the spliced ​​beam at the separation surface to the stress calculation point, in mm.

[0036] In this embodiment, based on the above finite element model, the spliced ​​beam mainly transmits the overall bending moment, and its force form can be simplified to pure bending. Therefore, the pure bending theoretical formula can be used to obtain the stress value at any position on the cross section, which is simple to calculate.

[0037] In another embodiment, the spliced ​​beams are any one of the splicing forms of circular tube beams spliced ​​with circular tube beams, circular axis beams spliced ​​with circular tube beams, square tube beams spliced ​​with square tube beams, trough beams spliced ​​with trough beams, or spliced ​​beams with other cross-sectional forms.

[0038] In another embodiment, the support structure includes a main beam, a main beam joint, a butt joint rib, a butt joint rib joint, which respectively support two spliced ​​beams; or other forms of support structures.

[0039] In another embodiment, when establishing the finite element models of each component in step S1, the main beam joint is simplified to RBE2 elements, which are used only to simulate the connection relationship; the main beam, butt rib, and butt rib joint are each modeled using two-dimensional shell elements. The RBE2 is a rigid multi-point constraint.

[0040] In another embodiment, when establishing the connection relationships between the components in step S2, the main beams are directly connected to the butt joint ribs at common nodes. The spliced ​​beams on both sides of the separation plane use RBE2 units to coordinate single-node to multi-node connections at one end connected to the main beam, and RBE3 units to coordinate single-node to multi-node connections at the other end connected to the butt joint rib. RBE3 is a flexible multi-point constraint.

[0041] The beneficial effects of the present invention are as follows: without introducing contact nonlinearity, the force transmission relationship of the plug-in quick-release wing separation surface connection structure can be accurately simulated in a concise and efficient manner through the combined use of commonly used basic units, thereby accurately calculating the bending stress of the plug-in beam structure, while greatly reducing the modeling complexity and significantly improving the calculation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Attachment Figure 1 This is a schematic diagram of a plug-in quick-detachable wing structure;

[0043] Attachment Figure 2 For attachment Figure 1 Schematic diagram of the internal structure of the middle A structure after removing the skin;

[0044] Attachment Figure 3 Schematic diagram of the finite element model of Example 1;

[0045] Attachment Figure 4 This is a partial schematic diagram of the finite element model of Example 1;

[0046] Attachment Figure 5 Schematic diagram of outputting the bending moment value at the separation surface of the spliced ​​beam in the finite element model in Example 1;

[0047] Attachment Figure 6 Schematic diagram of outputting the bending moment value at the separation surface of the spliced ​​beam in the finite element model in Example 2;

[0048] Attachment Figure 7 Schematic diagram of a finite element model of comparative example 1 in which the spliced ​​beams are simulated using two-dimensional shell elements and the splicing overlap area is simulated using the common node method;

[0049] Attachment Figure 8 For comparative example 1, the spliced ​​beams are simulated using two-dimensional shell elements and the spliced ​​overlap area is simulated using the common node method to simulate the stress cloud diagram;

[0050] Attachment Figure 9 The stress distribution curve along the length direction of the outer wing tube beam is obtained by simulating the splicing beam using two-dimensional shell element simulation and the splicing overlap area using the common node method in comparative example 1;

[0051] Attachment Figure 10 This is the stress cloud diagram of comparative example 2, in which the spliced ​​beam is simulated using two-dimensional shell element and the spliced ​​overlap area is simulated using contact nonlinear method;

[0052] Attachment Figure 11 This is a stress distribution curve along the length direction of the outer wing tube beam obtained by simulating the splicing beam of comparative example 2 using two-dimensional shell element simulation and the splicing overlap area using contact nonlinear method;

[0053] Attachment Figure 12 This is the stress cloud diagram of comparative example 3 where the spliced ​​beam is simulated using two-dimensional shell elements and the splicing overlap area is simulated using the contact nonlinear method;

[0054] Among them: 1-central wing main beam; 2-central wing main beam joint; 3-central wing tube beam; 4-central wing butt joint rib joint; 5-central wing butt joint rib; 6-outer wing butt joint rib; 7-outer wing tube beam; 8-outer wing butt joint rib joint; 9-outer wing main beam joint; 10-outer wing main beam. DETAILED DESCRIPTION

[0055] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part 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 those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0056] Example 1

[0057] The plug-in quick-release wing separation surface connection structure in this embodiment is shown in the attached Figure 1 and attached Figure 2 , including plug-in beams and supporting structures.

[0058] The spliced ​​beams are circular tube beams made of the same material, that is, the central wing tube beam 3 is inserted into the outer wing tube beam 7. The central wing tube beam 3 has an outer diameter of 34 mm and an inner diameter of 30 mm, and the outer wing tube beam 7 has an outer diameter of 30 mm and an inner diameter of 26 mm.

[0059] The supporting structure includes a main beam, a main beam joint, a butt-jointed rib, and a butt-jointed 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 butt-jointed ribs include a central wing butt-jointed rib 5 and an outer wing butt-jointed rib 6. The butt-jointed rib joint includes a central wing butt-jointed rib joint 4 and an outer wing butt-jointed 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 butt-jointed rib 5 through the central wing butt-jointed 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 butt-jointed rib 6 through the outer wing butt-jointed rib joint 8.

[0060] A finite element simulation method for a plug-in quick-release wing separation surface connection structure comprises the following steps:

[0061] S1. Establishing finite element models of various wing components, including: establishing a model of the splice beam using Bar units, dividing the splice beam into three sections and assigning attributes to each section, i.e., assigning attributes to the overlapping section of the splice beam according to the cross-sectional dimensions and equivalent material after superposition, and assigning attributes to the non-overlapping section according to the cross-sectional dimensions and materials of the two sections of the splice beam; establishing a model of the support structure using finite element units and assigning attributes to the actual thickness and material;

[0062] For details, see the attached Figure 3 The central wing tube beam 3 and the outer wing tube beam 7 are respectively modeled using Bar units, and the whole after the central wing tube beam 3 and the outer wing tube beam 7 are plugged in is divided into three sections and assigned attributes respectively. The overlapping part is assigned attributes according to the cross-sectional dimensions and equivalent materials after the central wing tube beam 3 and the outer wing tube beam 7 are plugged in and superimposed, and the non-overlapping part is assigned attributes according to their respective cross-sectional dimensions and materials; according to the plug-in fitting relationship of the plug-in beams, the outer wing tube beam 7 is an inner plug-in beam, and the central wing tube beam 3 is an outer plug-in beam.

[0063] The elastic modulus Ee and shear modulus Ge of the equivalent material of the overlapping portion of the spliced ​​beam are calculated using the following two formulas:

[0064] ;

[0065] ;

[0066] Where:

[0067] The elastic modulus of the material used for the internally connected beam along the axial direction of the beam, in MPa;

[0068] The elastic modulus of the material used for the external plug-in beam along the axial direction of the beam, in MPa;

[0069] is the section moment of inertia of the internally connected beam, in mm^4;

[0070] is the section moment of inertia of the external plug-in beam, unit is mm^4;

[0071] is the shear modulus of the material used for the internally connected beam within the beam section, in MPa;

[0072] is the shear modulus of the material used for the external plug-in beam within the beam section, in MPa;

[0073] is the cross-sectional area of ​​the internally connected beam, in mm^2;

[0074] is the cross-sectional area of ​​the external plug-in beam, in mm^2.

[0075] Since the inner and outer plug-in beams are made of the same material, E1 and E2 are the same, and G1 and G2 are the same, that is:

[0076] Ee=E1=E2;

[0077] Ge=G1=G2.

[0078] In addition, the main beam joint can be simplified to RBE2 units 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 units; the main beam, butt ribs, and butt rib joints can be 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 rib 5, the outer wing butt rib 6, the central wing butt rib joint 4, and the outer wing butt rib joint 8 are respectively modeled according to two-dimensional shell elements.

[0079] Furthermore, the method further comprises the steps of:

[0080] S2. Establishing the connection relationship between the various parts, wherein: the splicing beams are connected by nodes at the separation surface to simplify the interaction relationship of the simulated splicing; the splicing beams and their supporting structures are connected by multi-point constraint units to coordinate the connection relationship from a single node to multiple nodes;

[0081] For details, see the attached Figure 3 and attached Figure 4 The central wing tube beam 3 and the outer wing tube beam 7 are connected at the separation surface through node 1 to simplify the simulation of the interaction relationship between the central wing tube beam 3 and the outer wing tube beam 7 during the plug-in connection, ensuring the correct transmission of the overall shear force, torque, and main bending moment of the wing. The central wing tube beam 3 is connected to the central wing main beam 1 at one end through the RBE2 unit to coordinate the connection from a single node to multiple nodes, and the other end is connected to the central wing butt rib joint 4 through the RBE3 unit to coordinate the connection from a single node (node ​​three) to multiple nodes. The outer wing tube beam 7 is connected to the outer wing main beam 10 at one end through the RBE2 unit to coordinate the connection from a single node to multiple nodes, and the other end is connected to the outer wing butt rib joint 8 through the RBE3 unit to coordinate the connection from a single node (node ​​two) to multiple nodes.

[0082] In addition, the main beams are directly connected to the butt joint ribs at a common node. Specifically, the central wing main beam 1 is connected to the central wing butt joint rib 5 at a common node, and the outer wing main beam 10 is connected to the outer wing butt joint rib 6 at a common node.

[0083] Furthermore, the method further comprises the steps of:

[0084] S3. Calculation and analysis, including: loading and solving the wing overall model, extracting the nodal bending moment M of node 1 at the splice beam separation surface, and calculating the splice beam's bending stress. Since the bending moment is the main influencing quantity, the beam pure bending theory formula is used to calculate the splice beam's bending stress. The calculation formula is as follows:

[0085] ,

[0086] Where:

[0087] σ is the bending stress of the spliced ​​beam at the separation surface, unit: MPa;

[0088] M is the bending moment of the spliced ​​beam at the separation surface, in N·mm;

[0089] I is the section moment of inertia of the spliced ​​beam at the separation surface, in mm^4;

[0090] y is the distance from the centroid of the cross section at the separation surface of the spliced ​​beam to the stress calculation point, in mm;

[0091] Among them, the bending moment M value of the spliced ​​beam at the separation surface is calculated through the loading of the whole model. Figure 5 , is 581364N•mm;

[0092] The section moment of inertia at the separation surface of the spliced ​​beam and the distance from the section centroid to the stress calculation point can be calculated based on the spliced ​​beam parameters. The calculation formula is as follows:

[0093] ;

[0094] ;

[0095] Where:

[0096] D is the outer diameter of the outer wing tube beam 7

[0097] d is the inner diameter of the outer wing tube beam 7;

[0098] Substituting the corresponding parameters of the outer wing tube beam 7 into the formula, we can calculate: I=17329.02 mm^4, y=15mm.

[0099] Then M, I, y Substituting the corresponding numerical value into the bending stress formula, the bending stress of the spliced ​​beam at the separation surface is calculated to be 503.23 MPa.

[0100] In addition, the calculation log of the simulation process under this model shows that the calculation time is 2s.

[0101] Example 2

[0102] The difference between this embodiment and embodiment 1 is that the spliced ​​beams in this embodiment are square tube beams spliced ​​together, the cross-sectional height of the central wing tube beam is 34 mm, the width is 24 mm, and the tube wall thickness is 2 mm, and the cross-sectional height of the outer wing tube beam is 30 mm, the width is 20 mm, and the tube wall thickness is 2 mm.

[0103] A finite element simulation method for a plug-in quick-release wing separation surface connection structure comprises the following steps:

[0104] S1. Establishing finite element models of various wing components, including: establishing a model of the splice beam using Bar units, dividing the splice beam into three sections and assigning attributes to each section, i.e., assigning attributes to the overlapping section of the splice beam according to the cross-sectional dimensions and equivalent material after superposition, and assigning attributes to the non-overlapping section according to the cross-sectional dimensions and materials of the two sections of the splice beam; establishing a model of the support structure using finite element units and assigning attributes to the actual thickness and material;

[0105] Specifically, the central wing tube beam 3 and the outer wing tube beam 7 are respectively modeled using Bar units. The entirety of the central wing tube beam 3 and the outer wing tube beam 7 after being spliced ​​is divided into three sections and assigned attributes. The overlapping section is assigned attributes based on the cross-sectional dimensions and equivalent materials of the central wing tube beam 3 and the outer wing tube beam 7 after being spliced ​​and superimposed, and the non-overlapping sections are assigned attributes based on their respective cross-sectional dimensions and materials.

[0106] Since the inner and outer splicing beams are made of the same material, have the same elastic modulus and 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 splicing beams.

[0107] In addition, the main beam joint can be simplified to RBE2 units 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 units; the main beam, butt ribs, and butt rib joints can be 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 rib 5, the outer wing butt rib 6, the central wing butt rib joint 4, and the outer wing butt rib joint 8 are respectively modeled according to two-dimensional shell elements.

[0108] Furthermore, the steps include:

[0109] S2. Establishing the connection relationship between the various parts, wherein: the splicing beams are connected by nodes at the separation surface to simplify the interaction relationship of the simulated splicing; the splicing beams and their supporting structures are connected by multi-point constraint units to coordinate the connection relationship from a single node to multiple nodes;

[0110] Specifically, the central wing tube beam 3 and the outer wing tube beam 7 are connected at the separation surface through node 1 to simplify the simulation of the interaction relationship between the central wing tube beam 3 and the outer wing tube beam 7 during the plug-in connection, ensuring the correct transmission of the overall shear force, torque, and main bending moment of the wing. The end of the central wing tube beam 3 connected to the central wing main beam 1 coordinates the connection from a single node to multiple nodes through the RBE2 unit, and the other end and the central wing butt rib joint 4 coordinate the connection from a single node (node ​​3) to multiple nodes through the RBE3 unit. The end of the outer wing tube beam 7 connected to the outer wing main beam 10 coordinates the connection from a single node to multiple nodes through the RBE2 unit, and the other end and the outer wing butt rib joint 8 coordinate the connection from a single node (node ​​2) to multiple nodes through the RBE3 unit.

[0111] In addition, the main beams are directly connected to the butt joint ribs at a common node. Specifically, the central wing main beam 1 is connected to the central wing butt joint rib 5 at a common node, and the outer wing main beam 10 is connected to the outer wing butt joint rib 6 at a common node.

[0112] Furthermore, the method further comprises the steps of:

[0113] S3. Calculation and analysis, including: loading and solving the wing overall model, extracting the nodal bending moment M of node 1 at the splice beam separation surface, and calculating the splice beam bending stress. The calculation formula is as follows:

[0114] ;

[0115] Where:

[0116] σ is the bending stress of the spliced ​​beam at the separation surface, unit: MPa;

[0117] M is the bending moment of the spliced ​​beam at the separation surface, in N·mm;

[0118] I is the section inertia moment of the spliced ​​beam at the separation surface, in mm^4;

[0119] y is the distance from the cross-section centroid of the spliced ​​beam at the separation surface to the stress calculation point, in mm;

[0120] The bending moment M value of the spliced ​​beam at the separation surface is shown in the attached Figure 6 , the value is 609812N•mm;

[0121] The section moment of inertia of the spliced ​​beam at the separation surface and the distance from the section centroid to the stress calculation point can be calculated based on the spliced ​​beam parameters. The calculation formula is as follows:

[0122] ;

[0123] ;

[0124] Where:

[0125] b1 is the width of the outer wall of the outer wing tube beam 7 section;

[0126] h1 is the height of the outer wall of the outer wing tube beam 7 section;

[0127] b2 is the width of the inner wall of the outer wing tube beam 7 section;

[0128] h2 is the height of the inner wall of the section 7 of the outer wing tube beam;

[0129] Substitute the corresponding parameters of the outer wing tube beam 7 into the formula and calculate , .

[0130] Then add the above M, I, y The corresponding value is substituted into the calculation formula of bending stress, and the bending stress of the spliced ​​beam at the separation surface is calculated to be 424.17 MPa.

[0131] Comparative Example 1

[0132] The plug-in quick-release wing separation surface connection structure under this comparative example is the same as that of Example 1, except that the first finite element simulation method described in the background technology is adopted. Figure 7 , the spliced ​​beams are simulated using two-dimensional shell elements, and the spliced ​​overlap area elements are connected through common nodes; the specific steps are as follows:

[0133] Step 1: Establish finite element models of all wing components, including: using shell elements to establish plug-in beam and support structure models, and assigning properties according to actual thickness and material; simplifying the center wing main beam joint 2 and the outer wing main beam joint 9 into RBE2 elements;

[0134] Step 2: Establish the connection relationship between the components, including: connecting the units of the splicing beam in the splicing overlap area through a common node, and connecting the two main beam sections to the butt ribs at the common node; the splicing beams on both sides of the separation surface are connected to the main beam at one end through the RBE2 unit, and the other end is connected to the butt rib joint through the RBE3 unit;

[0135] Step 3: Load and calculate the whole model. The stress cloud diagram of the outer wing tube beam 7 is shown in the attached figure. Figure 8 As shown, the maximum stress at the separation surface is 650 MPa.

[0136] 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 cloud diagram, see the attached Figure 9Specifically, starting from the separation surface of the outer wing tube beam 7, a total of 7 units are selected at equal intervals along the length of the outer wing tube beam outward (left) and marked with unit numbers (unit numbers decrease from 6 to 0 in sequence). The internal and external surface stresses of the 7 units are plotted as a curve. From the 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. However, a "bifurcation" phenomenon occurs at unit 6, that is, the stress on the outer surface of the tube wall suddenly increases, while the stress on the inner surface suddenly decreases. This bifurcation trend is caused by the superposition of additional stress on the inner and outer surfaces of the tube wall caused by the local bending moment introduced by the common node method and the overall stress. This leads to an unrealistically large stress at the separation surface of the outer wing tube beam 7.

[0137] Comparative Example 2

[0138] The plug-in quick-release wing separation surface connection structure in this comparative example is the same as that in Example 1, except that the second finite element simulation method described in the background art is used, i.e., the plug-in beam is simulated using a two-dimensional shell element, and contact is set between the plug-in coincident surfaces. The specific steps are as follows:

[0139] Step 1: Establish finite element models of all wing components, including: using shell elements to establish plug-in beam and support structure models, and assigning properties according to actual thickness and material; simplifying the center wing main beam joint 2 and the outer wing main beam joint 9 into RBE2 elements;

[0140] Step 2: Establish the connection relationship between each part, including: connecting the two main beams to the common nodes of the butt ribs respectively; connecting one end of the one-side plug-in beam on the separation surface to the main beam through the RBE2 unit; and connecting the other end to the butt rib joint through the RBE3 unit;

[0141] Step 3: Establish contact between the overlapping surfaces of the spliced ​​beams, including:

[0142] 1) Define the contact surface: Select the outer surface of the shell element of the inner plug-in beam (outer wing tube beam 7) as one element set 1, and select the inner surface of the shell element of the outer plug-in beam (center wing tube beam 3) as another element set 2;

[0143] 2) Define contact properties: define normal "hard contact" behavior, define tangential "friction" behavior, and set the friction coefficient to 0.2;

[0144] 3) Establish a contact pair: Define a "face-to-face" contact pair, set element set 1 as the master surface and element set 2 as the slave surface; assign the contact properties defined in step 2) to the contact pair; define an appropriate adjustment tolerance based on the spatial position relationship between the two coincident surfaces to complete the contact setup.

[0145] Step 4: Load and calculate the entire model.

[0146] In this comparative example, due to the introduction of contact nonlinearity, the calculations did not converge. This required multiple model adjustments, such as adjusting the tolerances and replacing the master and slave surfaces, before the model finally converged. The time required for this adjustment process is closely related to the engineer's experience.

[0147] The stress cloud diagram of the outer wing tube beam 7 obtained when the final model reaches the convergence state is shown in the attached figure. Figure 10 As shown, the maximum stress at the separation surface is 498 MPa.

[0148] Combined stress cloud Figure 10 The stress distribution curve along the length direction of the outer wing tube beam is drawn, see the attached Figure 11 As can be seen from the graph, the stresses of the inner and outer wing tube beams 7 within the range of units 0-6 basically satisfy a linear relationship, and there is no "bifurcation" phenomenon that occurs in comparative example 1.

[0149] In addition, the calculation log of the simulation process after the model converged shows that the calculation time is 69s.

[0150] Comparative Example 3

[0151] The plug-in quick-release wing separation surface connection structure in this comparative example is the same as that in Example 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 a two-dimensional shell unit, and contact is set between the plug-in overlapping surfaces. The specific steps are the same as those in Comparative Example 2.

[0152] In this comparative example, after the first modeling, the calculation did not converge. After repeated debugging, the model finally reached a convergence state.

[0153] When the model reaches convergence, the stress cloud diagram of the outer wing tube beam 7 is shown in the attached figure. Figure 12 , showing that the maximum stress of the spliced ​​beam at the separation surface is 426.8MPa.

[0154] By analyzing and comparing the simulation analysis results of the above Examples 1-2 and Comparative Examples 1-3, it can be seen that:

[0155] 1) The bending stress values ​​obtained in Example 1 and Comparative Example 1 differ significantly, while the bending stress value in Comparative Example 2 is highly consistent with that in Example 1, confirming the effectiveness of the bending stress calculation in Example 1. This demonstrates that the present invention eliminates the unrealistic stress generated at the separation surface of the spliced ​​beam due to local bending moment, and the calculated bending stress value can meet the requirements of engineering design.

[0156] 2) Compared with Comparative Example 2, Example 1 avoids the occurrence of non-convergence of the calculation, thereby avoiding the need for repeated model debugging and saving modeling time. Compared with Comparative Example 2, Example 1 increases the calculation time and improves the calculation efficiency by 3350%. This shows that, under the premise of ensuring accurate stress calculation at the separation point of the spliced ​​beam, the present invention greatly simplifies the modeling process and calculation debugging process, significantly improving the calculation efficiency.

[0157] 3) The bending stress of Example 2 and the bending stress of Comparative Example 3 are very consistent, which shows that the present invention is applicable to the calculation of the bending stress at the separation surface of spliced ​​beams of any cross-section.

[0158] The above description is merely a detailed description of specific embodiments of the present invention. Any unspecified portions are conventional techniques. However, the scope of the present invention is not limited thereto. Any changes or substitutions that can be readily conceived by a person skilled in the art within the technical scope disclosed in the present invention are intended to be encompassed within the scope of the present invention. The scope of the present invention shall be determined by the scope of the claims.

Claims

1. A finite element simulation method for a plug-in quick-release wing separation surface connection structure, characterized in that: The connecting structure includes a splicing beam and a supporting structure for the splicing beam, and includes the following steps: S1. Establish finite element models of each part; S2. Establish the connection relationship between each part; S3, analysis and calculation; Step S1 establishes finite element models of each component, including: establishing a model of the spliced ​​beam using Bar units, dividing the spliced ​​beam into three segments and assigning them attributes, namely, assigning attributes to the overlapping portion of the spliced ​​beam according to the cross-sectional dimensions and equivalent materials after superposition, and assigning attributes to the non-overlapping portion according to the cross-sectional dimensions and materials of the two spliced ​​beam segments; establishing a model of the supporting structure using finite element units, and assigning attributes according to the actual state of the supporting structure; The step S2 establishes the connection relationship between the parts, including: the plug-in beams are connected by nodes at the separation surface to simplify the interaction relationship of the simulated plug-in; the plug-in beams and their supporting structures are connected by multi-point constraint units to coordinate the connection relationship from single nodes to multiple nodes.

2. The finite element simulation method for a plug-in quick-release wing separation surface connection structure according to claim 1, characterized in that: The equivalent material of the overlapping part of the spliced ​​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 spliced ​​beam section, respectively.

3. The finite element simulation method for a plug-in quick-release wing separation surface connection structure according to claim 1, characterized in that: The analysis and calculation in step S3 includes: The whole wing model is loaded and solved, the bending moment of the node at the separation surface of the splice beam is extracted, and the bending stress of the splice beam is calculated. The calculation formula is as follows: , Where: σ is the bending stress of the spliced ​​beam at the separation surface, unit: MPa; M is the bending moment of the spliced ​​beam at the separation surface, in N·mm; I is the section inertia moment of the spliced ​​beam at the separation surface, in mm^4; y It is the distance from the cross-section centroid of the spliced ​​beam at the separation surface to the stress calculation point, in mm.

4. The finite element simulation method for a plug-in quick-release wing separation surface connection structure according to claim 1, characterized in that: The spliced ​​beams are any one of the splicing forms of circular tube beams spliced ​​with circular tube beams, circular axis beams spliced ​​with circular tube beams, square tube beams spliced ​​with square tube beams, and trough beams spliced ​​with trough beams.

5. The finite element simulation method for a plug-in quick-release wing separation surface connection structure according to claim 1, characterized in that: The supporting structure comprises a main beam, a main beam joint, a butt joint rib and a butt joint rib joint respectively supporting two spliced ​​beams.

6. The finite element simulation method for a plug-in quick-release wing separation surface connection structure according to claim 5, characterized in that: When establishing the finite element model of each part in step S1, the main beam joint is simplified to RBE2 unit, 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 units.

7. The finite element simulation method for a plug-in quick-release wing separation surface connection structure according to claim 5, characterized in that: When establishing the connection relationship of each part in step S2, the main beam is directly connected to the butt rib at a common node; the plug-in beams on both sides of the separation surface coordinate the connection from a single node to multiple nodes at one end connected to the main beam through the RBE2 unit, and coordinate the connection from a single node to multiple nodes at the other end with the butt rib joint through the RBE3 unit.

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