Nail connection structure strength analysis method

Abstract

The invention discloses a method for analyzing the strength of a nail connection structure. The method comprises the following steps: establishing a three-dimensional model, establishing a grid division structure and defining a contact relationship and boundary conditions; establishing a one-dimensional beam unit model of the connecting piece, and generating and outputting unit and node information of the connecting piece; layered connection: carrying out corresponding layer number division on the one-dimensional beam unit model in the length direction according to the number of connected pieces and the local connection thickness, wherein each layer of beam unit is consistent with the local connected piece in thickness; and generating a model and analyzing. According to the analysis method disclosed by the invention, the connecting pieces are subjected to one-dimensional beam unit modeling, the connecting pieces with holes and the connecting pieces without holes are supported to be connected, and the one-dimensional beam units are automatically subjected to corresponding segmentation treatment according to local connected sizes; according to the method, the operation efficiency of a large-scale nail connection structure is high, the actual nail connection relation can be more accurately simulated, the analysis accuracy is ensured under the condition that the modeling and calculation efficiency is improved, and the nail and nail hole connection rigidity data can be upgraded.

Description

Technical Field

[0001] The present invention relates to the technical field of finite element simulation, and in particular to a method for analyzing the strength of a nail connection structure. Background Art

[0002] Finite element simulation analysis is a process of verifying the strength of a structure by meshing a three-dimensional solid structure and simulating its operating conditions by applying loads. Currently, when analyzing the location of connectors, such as bolts and rivets, the connector structure is removed and a point rigidly connected to the surrounding holes is simulated at the center of the connector to create an approximate connection effect. However, for aircraft connection structures with high precision and complex structures, the risk of fatigue damage from the nail hole connection is high, and more precise simulation calculations of the connectors are required. Accurately obtaining the connecting nail load and the bypass load of the connected parts is the basis for accurate analysis. At the same time, the presence of a large number of connectors in real aircraft structures not only increases the model processing workload and inefficiency, but also involves a large amount of contact analysis between the inner wall of the connector, the hole wall, and the connected parts, which affects the calculation efficiency and convergence, making it difficult to achieve accurate strength analysis of the connector location.

[0003] Therefore, how to improve the efficiency and accuracy of finite element analysis of the connector position is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0004] The present invention proposes a method for analyzing the strength of nail connection structures to improve the efficiency and accuracy of finite element analysis of the connection position.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A method for analyzing the strength of a nail-connected structure, comprising:

[0007] Establish a 3D model: Create a 3D solid unit grid structure for the structure to be analyzed, define the contact relationship between the connected parts and the boundary conditions for subsequent simulation calculations according to the analysis requirements, and output;

[0008] Establish a one-dimensional beam element model of the connector: Establish a finite element model of the connector based on the location, size, and material information of the connector, and output the unit and node information of the connector;

[0009] Layered connection: The one-dimensional beam element model of the connector is layered along its length according to the number of connected parts and the local connection thickness. For connected parts with open structures, the hole walls are geometrically constrained. For connected parts with non-open structures, the connection area is identified based on the dimensional information of the beam element. Displacement constraints and stiffness constraints are applied to the newly generated segmented beam element nodes as required.

[0010] Generate a model and analyze it. Output the connection model and node constraint information between the one-dimensional beam unit and the connected parts according to the layering situation. Import the generated layered connection model into the general analysis software and call the selected finite element solver to complete the simulation analysis of the nail connection structure.

[0011] Preferably, in the above-mentioned nail connection structure strength analysis method, in the step of establishing a one-dimensional beam unit model of the connecting part, the one-dimensional beam unit model of the connecting part exceeds the surface of the connected part at both ends in its length direction; in the layered connection step, the beam unit extending out of the surface of the connected part is cut off.

[0012] Preferably, in the above-mentioned nail connection structure strength analysis method, the two delamination areas located at both ends of the connecting member are delamination-offset with the constraint center point of the connected member toward the middle area.

[0013] Preferably, in the above-mentioned nail connection structure strength analysis method, stiffness displacement constraints and flexibility constraints are adopted between the outermost side of the one-dimensional beam unit model and the connected parts; axial constraints are set at the outermost surface nodes at the same time, and shear constraints are set at the area between the connected parts and the connecting parts at the same time to simulate the axial constraints of the bolt head or nut of the actual structure and the shear conditions of the screw.

[0014] Preferably, in the above-mentioned nail connection structure strength analysis method, the stiffness displacement constraint and the flexible constraint are connected by simulating the constraint via a spring element simulating the shear stiffness of the bolt.

[0015] Preferably, in the above-mentioned nail connection structure strength analysis method, in the radial direction of the connecting member, three nodes are arranged at the same position of the layered beam unit, namely a flexible unit (RBE3), a spring unit and a rigid unit (RBE2). The flexible unit on the outermost surface constrains the axial direction and three rotational directions, and the spring unit is located in the middle position.

[0016] Preferably, in the above-mentioned nail connection structure strength analysis method, the number of layers of the one-dimensional beam unit located in the middle area is equal to the number of the connected parts, and the thickness of the single layer is consistent and aligned with the corresponding connected parts.

[0017] Preferably, in the above-mentioned nail connection structure strength analysis method, in the step of establishing a one-dimensional beam unit model of the connecting member, the unit and node information of the connecting member is generated and output, including at least the number, size, position of the connecting member, and the material of the connecting member to reflect the geometric information and stiffness information of the connecting member.

[0018] Preferably, in the above-mentioned nail connection structure strength analysis method, in the establishment of the three-dimensional model, the three-dimensional model has a three-dimensional unit filling at the opening position of the connecting member, and in the layered connection step, the one-dimensional beam unit model of the connecting member directly passes through the three-dimensional unit filling at the opening position.

[0019] Preferably, in the above-mentioned nail connection structure strength analysis method, in the layered connection step, the one-dimensional beam unit model is layered and outputs the layer number and thickness information, node position information and connection area information of each layered area and the connected parts of the beam unit.

[0020] It can be seen from the above technical solution that the nail connection structure strength analysis method provided by the present invention performs one-dimensional beam unit modeling on the connector so that there is a solid grid connection between the connector and the connected parts, rather than a simple rigid constraint. The connector modeling with the help of one-dimensional beam units can be applicable to the three-dimensional model of the connected parts of the open structure, or the three-dimensional model of the connected parts of the closed structure. It is only necessary to determine the setting position of the connector. For the connected parts of the open structure, the subsequent geometric constraints are the hole wall and the outer wall of the connector. For the connected parts of the non-open structure, the connection area, that is, the outer wall area of the connector, is identified through the size information of the beam unit, and a new constraint relationship between the outer wall area of the connector and the surrounding connected parts is established. The above method does not require excessive processing on the grid structure of the connected parts, but only needs to identify the connection position of the connector and pass through the grid model setting of the connected parts through the one-dimensional beam unit modeling of the connector. On the aircraft model with a porous structure, the modeling efficiency of the connection structure strength analysis process can be significantly improved. On this basis, the one-dimensional beam unit model is layered in its length direction, specifically according to the number of connected parts and the local connection thickness size. That is, for the connected parts of two-layer or multi-layer structures, each layer has a connector layer node corresponding to its thickness, and the single-layer connected parts are connected to the corresponding layer node, and displacement constraints and stiffness constraints are set. The connector can form two or more simulated constrained connection structures with the connected parts. Compared with the simple grab point constraints in the prior art, it has a more refined constrained connection structure and is closer to the fixed state of the nail connection structure under actual working conditions, so that more accurate strength analysis results can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some examples or embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on the provided drawings without inventive work, and the present invention can also be applied to other similar scenarios based on the provided drawings. Unless otherwise apparent from the language context or otherwise explained, the same reference numerals in the figures represent the same structure or operation.

[0022] Figure 1 is a schematic diagram of the physical connection structure between the connector and the connected component provided by an embodiment of the present invention;

[0023] Figure 2 It is a schematic diagram of the constraint structure of the connecting member and the connected member;

[0024] Figure 3 Schematic diagram of hierarchical connection between the one-dimensional beam element of the connecting member and the grid structure of the connected member;

[0025] Figure 4 It is a front view of the contact structure of two connected parts;

[0026] Figure 5 It is a schematic diagram for marking the connection position on the connected parts;

[0027] Figure 6 It is a grid structure diagram of the connecting parts and connected parts of the physical structure;

[0028] Figure 7 for Figure 6 A top view of

[0029] Figure 8 A schematic diagram of the grid structure of the connecting member and the connected member of the one-dimensional beam unit model provided in an embodiment of the present disclosure;

[0030] Figure 9 for Figure 8 A top view of

[0031] Figure 10 A schematic diagram of the grid structure of the layered constraints of the connecting parts after holes are opened on the connected parts;

[0032] Figure 11 for Figure 10 A top view of

[0033] Figure 12 Flowchart of the method for analyzing the strength of nail connection structures provided in an embodiment of the present disclosure.

[0034] Among them: 10-connecting part; 20-connected part; 310-flexible unit; 320-rigid unit; 330-spring constraint. DETAILED DESCRIPTION

[0035] The core of this application is to disclose a method for analyzing the strength of nail connection structures to improve the efficiency and accuracy of finite element analysis of the connection position.

[0036] To help those skilled in the art better understand the present invention, embodiments of the present invention are described below with reference to the accompanying drawings. The embodiments described below do not limit the invention as set forth in the claims. Furthermore, the entire contents of the configurations shown in the embodiments below are not necessarily required to serve as the solution to the invention as set forth in the claims.

[0037] See also Figure 1-12 The nail connection structure strength analysis method disclosed in the embodiment of the present invention is used to perform a more accurate strength analysis of the structure connected by bolts, rivets and other connecting members 10 at the location of the connecting member 10. Specifically, Figure 12 As shown, the nail connection structure strength analysis method includes at least the following steps:

[0038] S01: Create a three-dimensional model.

[0039] The establishment of a three-dimensional model structure is the basis of strength analysis. First, a three-dimensional solid unit grid division structure is established for the analyzed structure, and the contact relationship between the connected parts 20 is defined according to the analysis needs, such as surface-to-surface contact, surface-line contact, etc. At the same time, the boundary adjustment of subsequent simulation calculations is determined according to the analysis needs, that is, the fixed end, free end and outer side force conditions of the connected parts 20 under actual working conditions, so as to make the model closer to the actual operating conditions and provide a reliable basis for subsequent analysis.

[0040] After the above information is determined, it is output. It should be noted that in step S01, the opening problem of the connected part 20 is not considered, that is, there is no need to consider the installation structure of the connector 10, but only the connected part 20 is modeled and meshed; at the same time, the appropriate mesh type and density are selected according to the complexity of the structure and the analysis accuracy requirements.

[0041] Based on the above structure, in step S01, no further processing such as digging holes is performed on the connected parts 20 to reduce the difficulty of model processing under the working conditions of a large number of connecting parts 10. Therefore, in step S01, the positions of the connecting parts 10 need to be marked to clarify the relative position relationship between the connecting parts and the connected parts 20 on the connected parts 20, providing an accurate reference for the subsequent establishment of the model of the connecting parts 10. At the same time, Figure 4 and Figure 5As shown, the position marking of the connector 10 can be performed by coordinate positioning, geometric feature positioning, etc. to ensure the accuracy of the connection position.

[0042] S02: Establish a one-dimensional beam element model of the connector.

[0043] Unlike the conventional method of simulating connections by opening and grabbing points at the connection locations, in the disclosed embodiment, the connector 10 is established as a one-dimensional beam unit model based on information such as its installation location, selected dimensions, and material. Simultaneously, according to the connection location marked in step S01, the one-dimensional beam unit model of the connector 10 is passed through the model of the connected component 20 for installation. It should be noted that the one-dimensional beam unit model is a widely used model in structural analysis that can effectively simulate the mechanical behavior of the connector 10. After the one-dimensional beam unit model is passed through the connected component 20 for installation, the unit and node information of the connector 10 is simultaneously output, namely, information such as the number, node coordinates, and unit length of the connection unit formed by each connector 10 and the surrounding structure, and the unit and node information is recorded.

[0044] It should be noted that in step S02, after the one-dimensional beam unit model is passed through the connected part 20, a stiffness information database can be generated based on the thickness of the connected part 20, that is, the thickness of the interlayer, the type of the connecting part 10, such as rivets, bolts, etc., and the connection stiffness, so as to provide more comprehensive and accurate data support for subsequent reference and analysis.

[0045] S03: Hierarchical connection.

[0046] Specifically, in step S03, Figure 3 As shown, the one-dimensional beam unit model of the connector 10 is layered according to the number of connected parts 20 and the local connection thickness size. The number of connected parts 20 and the local connection thickness size information have been output in advance, and the one-dimensional beam unit of the connector 10 is automatically layered to form the corresponding number of layers based on the above information, and each layer of structural area is only connected to the corresponding area of the connected part 20 that is flush with it. At the same time, during the connection process, the connection unit is centered and constrained on the axis of the connector 10 to ensure the stability of the connection and avoid additional stress and deformation caused by eccentric connection.

[0047] It should be noted that the nodes of the newly generated segmented beam units on the connector 10 are subjected to displacement constraints and stiffness constraints as required, that is, the newly generated segmented beam units on the connector 10 are subjected to MPC (multi-point constraint) connection. It should be noted that MPC connection is a method commonly used in the finite element analysis process, which realizes the simulation of physical phenomena such as rigid connection and load transfer by establishing a coupling relationship between different node degrees of freedom. It is commonly explained as Multipoint constraint, that is, in the present disclosure, appropriate multi-point constraints are established for each node of the beam unit and the nodes near the connected member 20, and at the same time, multi-point connections considering stiffness are established by considering different layer thicknesses, bolt diameters and other information, so as to be able to more comprehensively simulate the interaction between the connector 10 and the connected member 20.

[0048] That is, for the connecting part 10, its locking of the connected part 20 is achieved by the pressure and torsion limiting effect on the surrounding connected parts 20 through the area where it passes through the connected part 20, and all parts of the structure of the connecting part 10 passing through the area of the connected part 20 generate stress with the surrounding connected parts 20. However, the currently commonly used rigid connection simulation is mostly through the connection simulation with the surrounding connected parts 20 at a single point located in the center of the connecting part 10, which is quite different from the actual working conditions. The embodiment of the present disclosure uses a layered setting of the one-dimensional beam unit model of the connector 10, which can achieve a more refined connection simulation of the area where the connector 10 passes through the connected parts 20. Each layer of the connected parts 20 has a corresponding beam unit structure with the same thickness, so that each layer of the connected parts 20 is constrained to be connected to its corresponding beam unit and is constrained to be centered on the axis of the connector 10. The connector 10 is divided into several connection areas. Due to the one-dimensional beam unit model, the multiple connection areas maintain internal stress effects, and the outsides of the multiple connection areas can perform stress simulation on the areas of the connected parts 20 that they are in contact with, without acting on the dislocated areas of the connected parts 20, thereby accurately refining the force on the connector 10. It should be noted that by layering the connector 10, the stress conditions and deformation behaviors of the connector 10 at different positions can be more accurately simulated, thereby providing more detailed and accurate data support for subsequent strength analysis.

[0049] It should be noted that in step S03 , the analyst can input the single layer thickness of the connector 10 , and perform local manual adjustments as needed based on the automatic layering of the connector 10 , thereby achieving a more refined layered structure of multiple connectors 10 .

[0050] It should be further explained that in step S03, it is only necessary to determine the setting position of the connecting member 10 without considering the open state of the connected member 20. In fact, for the connected member 20 with an open structure, the subsequent geometric constraints are the hole wall and the outer wall of the connecting member 10, and for the connected member 20 with a non-open structure, the connection area, that is, the outer wall area of the connecting member 10, is identified through the size information of the beam unit, and a new constraint relationship between the outer wall area of the connecting member 10 and the surrounding connected members 20 is established. The above method does not require excessive processing of the grid structure of the connected member 20. It only requires the connection position identification of the connecting member 10 and the one-dimensional beam unit modeling of the connecting member 10 through the grid model setting of the connected member 20. On an aircraft model with a porous structure, the modeling efficiency of the connection structure strength analysis process can be significantly improved.

[0051] S04: Generate model and analyze.

[0052] According to the layering situation, the connection model and node constraint information of the one-dimensional beam unit and the connected member 20 are output. At the same time, the generated layered connection model is imported into a general commercial analysis software, and the selected finite element solver is called to complete the static analysis, dynamic analysis, fatigue analysis, etc. of the connection structure. The finite element solver calculates the mechanical parameters such as stress, strain, displacement, etc. of the connection structure based on the above information, thereby providing a reliable strength assessment basis for further design; and the layered connection model is imported into the analysis software to store and view the MPC connection information of the segmented beam unit on the connector 10 in the above steps, as well as the related node and coordinate information.

[0053] In order to further improve the simulation accuracy of the connection unit, in some embodiments of the present disclosure, the two ends of the one-dimensional beam unit model in the length direction extend beyond the surface of the connected part 20 to simulate the working condition that the two ends of the connector 10 usually extend beyond the surface of the connected part 20, thereby more realistically reflecting the stress conditions of the connector 10 in actual engineering. In step S03, the beam unit structure of the connector 10 that extends beyond the surface of the connected part 20 is truncated to ensure that the connector 10 maintains the same thickness as the connected part 20, thereby achieving more precise docking between the two and ensuring the stiffness effect of the connected part 20. The vertical support effect of the bolts and nuts is achieved by setting vertical stiffness constraints at the nodes at the corresponding positions.

[0054] It should be noted that, in other embodiments, the beam unit structure of the connector 10 extending beyond the surface of the connected part 20 is not processed, so that the structures such as the bolt head and nut extending beyond the surface of the connected part 20 are also simulated. It should be noted that, for the beam unit structure of the connector 10 extending beyond the surface of the connected part 20, the areas at both ends of the connector 10 extending beyond the connected part 20 can not only bear the load, but also have a certain impact on the strength of the layered structure at both ends of the connector 10. By simulating the structure beyond the surface of the connected part 20 using a one-dimensional beam unit model, the problem of inaccurate simulation of the stress conditions at both ends of the connector 10, which may be caused by the two ends of the connector 10 being flush with the surface of the connected part 20, is avoided. The influence of the end area of the connector 10 on the strength and load distribution of the connecting unit can be simulated more accurately, thereby improving the accuracy of the structural strength analysis of the entire connecting unit position.

[0055] On the basis of the above embodiment, the areas at both ends of the connector 10 that exceed the connected parts 20 will form an asymmetric mechanical relationship structure with the connected parts 20 after layering. For the layered structure at both ends, it includes areas that exceed the surfaces of the connected parts 20 on both sides. During the connection process of the connector 10, the areas that exceed the surfaces of the connected parts 20 on both sides do not generate a connection effect with the surrounding connected parts 20, or only generate a small connection force. At this time, the single-layer structure is connected by centering the constraint on the axis of the connector 10, which will cause the simulation state to be different from the actual operating condition. Therefore, in some embodiments of the present invention, In the embodiment, for the beam unit structure in which the connecting member 10 extends out of the surface of the connected member 20, the two layered regions located at the two ends of the connecting member 10 are offset from the constraint center point of the connected member 20 toward the axial center region of the connecting member 10, so that the layered regions of the connecting member 10 at both ends and the constraint center points of the surrounding connected members 20 are located within the range of the connected member 20, and at the same time, the structure simulation beyond the area of the connected member 20 is made to bear a smaller connection force, which can more accurately reflect the actual mechanical interaction between the connecting member 10 and the connected member 20, thereby improving the accuracy and reliability of the analysis.

[0056] It should be further explained that for the outermost side of the one-dimensional beam unit model of the connector 10, stiffness displacement constraints and flexibility constraints are adopted between it and the connected part 20. At the same time, shear constraints are also set between the contact area of the connected part 20 and the connector 10. That is, the locking effect of the connector 10 on the connected part 20 and the shear effect of the contact surface on the connector 10 when different connected parts 20 are subjected to different forces are taken into account at the same time, and the axial constraints of the bolt head or nut of the actual structure and the shear conditions of the screw are simulated, thereby providing a more accurate model basis for subsequent strength calculations.

[0057] For the one-dimensional beam unit model, the connector 10 and the connected member 20 are rigidly connected. However, when the connector 10 is stressed to the yield limit, it will deform to a certain extent before being destroyed and maintain the connection effect. In order to more accurately simulate the complex mechanical relationship in the above structure, Figure 2 As shown, in some embodiments of the present disclosure, in step S02 and step S03, the outermost side of the one-dimensional beam unit model, that is, the outer wall area of the connector 10, and the connected part 20 are constrained by flexible units 310, while in the area close to the central axis of the connector 10, the one-dimensional beam unit model is constrained by rigid units 320, and on the basis of the above embodiment, the flexible unit 310 and the rigid unit 320 are connected by spring constraints 330. It should be noted that during the simulation process, the flexible unit 310 constraint can better simulate the possible gap between the connector 10 and the connected part 20, as well as the relative deformation effect after the two come into contact, and the parameter setting of the flexible unit 310 is adjusted according to the actual mechanical requirements and material properties. The rigid unit 320 constraint in the axis area of the one-dimensional beam unit model can simulate the force inside the connector 10, ensuring the rigid transmission effect of the force. At the same time, the spring constraint 330 connection is used to realize the transmission of the force between the flexible unit 310 and the rigid unit 320. The spring constraint 330 has both flexible and rigid effects. For the contact deformation area on the connecting member 10 and the rigidity area of the axis, the connection between the two is achieved through the spring constraint 330, which can better simulate the transition structure between the force-bearing deformation area and the rigid support area on the connecting member 10 under actual working conditions. Similarly, the spring constraint 330 can set different stiffness parameters according to actual needs, thereby simulating different degrees of transition connections.

[0058] During the layered connection process, the one-dimensional beam unit model of the connector 10 is layered in its length direction, and each layered area is connected to the corresponding connected part 20 that is flush with it. Each layer area is connected to the connected part 20 from the outside to the inside through the flexible unit 310 constraint, the spring constraint 330 and the rigid unit 320 constraint, thereby achieving a more accurate simulation of the working condition of the connector 10.

[0059] Furthermore, based on the one-dimensional beam unit model structure in which the flexible unit 310 and the rigid unit 320 coexist, in some embodiments of the present disclosure, the flexible unit 310 is arranged to be aggregated toward the axis of the one-dimensional beam unit model. It should be noted that the setting of the flexible unit 310 needs to be aggregated into a rigid action point, that is, while the outer wall area of the connector 10 is subjected to a certain degree of deformation simulation, it is still necessary to form a rigid action point to realize the contact state simulation between the connector 10 and the connected member 20, thereby avoiding simulation deviation caused by disordered deformation of the flexible unit 310; and for the rigid unit 320 near the axis area of the connector 10, 0, along the radial parallel constraint of the one-dimensional beam unit model, after the flexible unit 310 aggregates the force acting on the outer wall of the connection, the rigid unit 320 needs to transmit the force acting on it in parallel, that is, the strength achieved by the radial dimension of the connector 10 is used to resist the force acting on the connector 10, and the rigid unit 320 with radial parallel constraint along the one-dimensional beam unit model can ensure the parallel transmission of the force, so that each position of the connector 10 can bear the force, and will not cause excessive force on the local area of the connector 10 due to excessive aggregation of the force, and thus cause local fracture problems during the simulation process.

[0060] It should also be noted that for the layered structure of the one-dimensional beam element, the number of layers is preferably equal to the number of connected components 20, that is, each connected component 20 has a corresponding layer node, and the corresponding layer node is equal to and aligned with the thickness of the connected component 20, thereby improving the accuracy of the model simulation process. Similarly, in other embodiments of the present invention, the layered structure of the one-dimensional beam element can be further subdivided so that a single connected component 20 corresponds to two or more layer nodes in its thickness direction, and it is only necessary to keep the two sides of the connected component 20 in the thickness direction aligned with the layer nodes.

[0061] Furthermore, in the nail connection structure strength analysis method provided in the embodiment of the present disclosure, step S03 is essentially to achieve more accurate force simulation by finely segmenting the one-dimensional beam unit model of the connector 10. In order to improve the simulation accuracy of the one-dimensional beam unit for the actual working condition of the connector 10, in some embodiments of the present disclosure, in the multi-layered structure of the one-dimensional beam unit, the layered structure located in the middle area has the same thickness. It should be noted that for the layering of the connector 10 of the one-dimensional beam unit model, multiple connection units are actually formed between the connector 10 and the connected member 20 to improve the simulation accuracy. For the connector 10 with uniform size, the area in contact with the connected member 20 has a similar force state. Therefore, the layered structure of the one-dimensional beam unit located in the middle area is set to a structure with the same thickness, so that its mechanical behavior in the middle area is uniform and consistent. The middle area, as the main load-bearing structure, can balance the force of the connector 10 and improve the accuracy of the strength analysis of the surrounding structure of the connector 10.

[0062] Furthermore, in step S02, the unit and node information of the connector 10 is generated and output, including at least the number, size, position of the connector 10, and the strength information corresponding to the material of the connector 10, so as to provide more comprehensive and accurate data support for subsequent analysis. It should be noted that the number of the connector 10 is used to uniquely identify each connector 10, which is convenient for management and reference in subsequent analysis. The size and position information limits the geometric characteristics of the connector 10 and its specific position in the structure, while the material and strength information includes key parameters such as the elastic modulus, yield strength, and tensile strength of the connector 10 material, which directly affect the mechanical response of the connector 10 when subjected to force. By outputting the above information, it is possible to trace the source and modify some parameters during the analysis process, and conduct comparative experimental analysis under different working conditions.

[0063] In step S01, when establishing the three-dimensional model, the position for installing the connector 10 in the three-dimensional model is closed, that is, no hole digging operation is performed, so that the structure of the connected part 20 in the three-dimensional model remains continuous, which can simplify the model and mesh processing process and improve the efficiency of the analysis process. In steps S02 and S03, after the connector 10 of the one-dimensional beam unit model is brought into contact with the established three-dimensional model mesh division structure, local mesh processing is performed to directly adjust the layering and connection relationship between the connector 10 and the connected part 20 of the one-dimensional beam unit model through the mesh structure, thereby improving the efficiency of the modeling and analysis process.

[0064] Furthermore, in step S03, the one-dimensional beam unit model needs to output the number of layers of the beam unit and the thickness information of each layered area after layering. At the same time, it needs to output the position information of the connection node on the three-dimensional model and the connection area information of each layered area and the connected part 20. The above output information can provide accurate input data for strength analysis, and can intuitively check the influencing factors based on the analysis results, thereby ensuring the data integrity and reproducibility of the strength analysis process, and providing a parameter basis for control experimental analysis.

[0065] In a specific embodiment of the present disclosure, a simple shear connection structure is used as an example. In this embodiment, four rows and two columns of connectors 10 are arranged to secure a connected member 20. Specifically, the connected member 20 is 180 mm long, 56 mm wide, and 5 mm thick, and is staggered and fitted on one side. The diameter of the connection hole in actual working conditions is 5 mm. The left end of the connection structure is clamped and constrained, and a 10 kN load is applied to the right end.

[0066] The specific strength analysis steps for this connection structure are as follows: Figure 6 and Figure 7 As shown, the physical structure comparison example, and Figure 10 and Figure 11 As shown, the connected member 20 is opened and the connecting structure is only provided inside the opening area. Figure 8 、 Figure 9 as well as Figure 12 As shown, the analysis steps are:

[0067] Step 1: Use commercial software to establish a detailed analysis model of the connected part 20 of a three-dimensional solid model, apply boundary conditions and other information; generate detailed model information of the connected part 20, which may include contact effects, prestress, etc.

[0068] Step 2: Determine the connection position, mark eight array positions on the 3D solid model, and number each position.

[0069] Step 3: Create a one-dimensional beam element to simulate the bolt based on the position and size of the connected parts. This element is divided into one unit. In the subsequent layered connection, the beam element layer will be automatically layered based on the number and size of the connected parts 20. At the same time, the one-dimensional beam element information including the connecting part 10 is generated.

[0070] Step 4: Based on the connection dimensions of the connector 10, the connection stiffness is calculated as the stiffness simulation information of the connection unit. At the same time, the beam unit is automatically layered, and the grid connection division between each layer of the beam unit and the connected component 20 is completed.

[0071] Step 5: After completing the model processing, perform stress analysis. The calculation results are shown in the table below.

[0072]

[0073] It can be seen that the nail connection structure strength analysis method of the embodiment of the present application generates an analysis structure without a nail hole structure, which has a smaller load calculation error and higher strength analysis accuracy compared to the operating conditions of physical nails.

[0074] As used herein and in the claims, unless the context clearly indicates otherwise, the terms "comprise" and "include" only imply the inclusion of the steps and elements specifically identified, and these steps and elements do not constitute an exclusive list; a method or apparatus may also include other steps or elements. The phrase "comprises a..." does not preclude the presence of other identical elements in the process, method, product, or apparatus that includes the elements.

[0075] The above description is merely an illustration of preferred embodiments of the present invention and the technical principles employed, and is not intended to limit the present invention. Persons skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. The scope of the invention is not limited to technical solutions formed by a specific combination of the aforementioned technical features. It also encompasses other technical solutions formed by any combination of the aforementioned technical features or their equivalents, without departing from the aforementioned inventive concept. For example, a technical solution formed by replacing the aforementioned features with (but not limited to) technical features having similar functions disclosed in this invention.

Claims

1. A method for analyzing the strength of a nail connection structure, characterized in that: include: Establish a 3D model: Create a 3D solid unit grid structure for the structure to be analyzed, define the contact relationship between the connected parts and the boundary conditions for subsequent simulation calculations according to the analysis requirements, and output; Establish a one-dimensional beam element model of the connector: Establish a finite element model of the connector based on the location, size, and material information of the connector, and output the unit and node information of the connector; Layered connection: The one-dimensional beam element model of the connector is layered along its length according to the number of connected parts and the local connection thickness. For connected parts with open structures, the hole walls are geometrically constrained. For connected parts with non-open structures, the connection area is identified based on the dimensional information of the beam element. Displacement constraints and stiffness constraints are applied to the newly generated segmented beam element nodes as required. Generate a model and analyze it. Output the connection model and node constraint information between the one-dimensional beam unit and the connected parts according to the layering situation. Import the generated layered connection model into the general analysis software and call the selected finite element solver to complete the simulation analysis of the nail connection structure.

2. The method for analyzing the strength of a nail connection structure according to claim 1, wherein: In the step of establishing a one-dimensional beam element model of the connecting part, both ends of the one-dimensional beam element model of the connecting part in the length direction exceed the surface of the connected part; in the layered connection step, the beam elements extending out of the surface of the connected part are cut off.

3. The method for analyzing the strength of a nail connection structure according to claim 2, wherein: The two layered areas located at both ends of the connecting member are offset from the constraint center point of the connected member toward the layered area of the middle area.

4. The method for analyzing the strength of a nail connection structure according to claim 2, wherein: Stiffness displacement constraints and flexibility constraints are adopted between the outermost side of the one-dimensional beam unit model and the connected parts; axial constraints are set at the outermost nodes, and shear constraints are set at the areas between the connected parts and the connecting parts to simulate the axial constraints of the bolt head or nut and the shear conditions of the screw in the actual structure.

5. The method for analyzing the strength of a nail connection structure according to claim 4, wherein: The stiffness displacement constraint and the flexible constraint are connected by a spring element simulating the shear stiffness of the bolt.

6. The method for analyzing the strength of a nail connection structure according to claim 5, wherein: In the radial direction of the connecting part, three nodes are arranged at the same position of the layered beam element, namely a flexible element (RBE3), a spring element and a rigid element (RBE2). The flexible element on the outermost surface constrains the axial direction and three rotational directions, and the spring element is located in the middle position.

7. The method for analyzing the strength of a nail connection structure according to claim 3, wherein: The number of layers of the one-dimensional beam unit located in the middle region is equal to the number of the connected parts, and the thickness of the single layer is consistent with and aligned with the corresponding connected parts.

8. The method for analyzing the strength of a nail connection structure according to claim 1, wherein: In the step of establishing a one-dimensional beam element model of the connector, the element and node information of the connector is generated and output, including at least the number, size, position, and material of the connector to reflect the geometric information and stiffness information of the connector.

9. The method for analyzing the strength of a nail connection structure according to claim 1, wherein: In the three-dimensional model building, the three-dimensional model has three-dimensional unit filling at the opening position of the connector, and in the layered connection step, the one-dimensional beam unit model of the connector directly passes through the three-dimensional unit filling at the opening position.

10. The method for analyzing the strength of a nail connection structure according to claim 1, wherein: In the layered connection step, after the one-dimensional beam element model is layered, the layer quantity and thickness information, node position information, and connection area information between each layer area and the connected member of the beam element are output.

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