A method for simulating a bolted joint
By simulating bolt connections using hexahedral mesh elements, combined with DISCRETE elements and preload, the problem of refining and improving the efficiency of bolt connection simulation analysis in whole-vehicle collision analysis was solved. This achieved high-precision bolt stress simulation and provided guidance for bolt specification selection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA FAW CO LTD
- Filing Date
- 2023-03-28
- Publication Date
- 2026-07-10
AI Technical Summary
In existing technologies for whole-vehicle collision analysis, it is difficult to achieve high precision and efficiency in the simulation analysis of bolted connections without significantly increasing the computation time. Furthermore, existing methods suffer from insufficient accuracy or excessive computation time in simulating bolt deformation and failure.
Hexahedral mesh elements are used to simulate bolt connections. By creating meshes of nuts, bolts, and connected parts, material properties are assigned, and the connection relationship between bolts and connected parts is set. DISCRETE elements and preload are used to simulate bolt deformation and stress. Force sensors are set up using keywords to extract bolt stress.
It enables refined simulation analysis of bolted connections without significantly increasing computation time and modeling workload, improves calculation accuracy, and can extract the overall stress and strain of bolts to guide bolt specification selection and simulate bolt fracture.
Smart Images
Figure CN116362034B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of whole vehicle collision analysis technology, specifically relating to a simulation method for bolted connections. Background Technology
[0002] As vehicle collision analysis models become increasingly sophisticated, the stress on many bolts within the vehicle needs to be assessed, and the simulation analysis of bolt connections also needs to be further refined without significantly increasing computation time. Previous bolt simulation methods often failed to achieve a balance between sophistication and efficiency.
[0003] Typically, bolted connections in collision simulation analysis models are handled using the following methods: 1. A completely rigid connection between the connected parts, which cannot account for bolt deformation and failure, making it impossible to predict failure and guide design. 2. Using beam elements for simulation, rigidly connecting the two ends of the beam element and the bolt holes of the top and bottom two connected parts. This can account for bolt fracture and extract bolt stress, but the accuracy is low, and it is prone to erroneous local deformation when dealing with long bolts, large deformation in the area, or multiple connected parts. 3. Using a hexahedral mesh method, which can account for local bolt deformation and preload, but it is difficult to extract bolt stress. 4. Local fine-grained modeling, considering the influence of the manufacturing process, results in excessively long computation time, suitable for simulating single weld points or small models, but not suitable for whole vehicle models. Therefore, there is an urgent need to develop a simulation method for bolted connections to effectively solve the above problems. Summary of the Invention
[0004] The purpose of this invention is to provide a bolt connection modeling method that can be used for finite element analysis of whole vehicle collisions, so as to solve the problem of further refining the simulation analysis of bolt connections without significantly increasing the computation time.
[0005] The objective of this invention is achieved through the following technical solution:
[0006] A simulation method for bolted connections includes the following steps:
[0007] A. Create a nut mesh and assign material properties: When creating a nut mesh, if the nut shape is complex, the mesh can be divided into regions. Each region uses a shell element mesh stretched along the axial direction. When connecting different regions, the nodes correspond one-to-one and mesh.
[0008] B. Establishing the bolt mesh and assigning material properties: When establishing the bolt mesh, divide the mesh into regions and use the shell element mesh to stretch along the axial direction. When connecting the bolt regions, the nodes correspond one-to-one and mesh. The mesh nodes of the bolt and nut contact surfaces correspond one-to-one and mesh. When establishing the bolt connection solid mesh, define the contact surface between the nut and the connected part as surface 1, and the contact surface between the bolt head and the connected part as surface 2. Establish a node at the center of surface 1 and surface 2, namely center 1 and center 2. The bolt mesh should contain these two nodes.
[0009] C. Create the mesh of the connected parts and assign material properties: The connected parts can be divided into solid meshes or shell meshes, and the mesh near the bolt holes needs to be specially divided.
[0010] C1. Mesh creation for bolt holes of connected component 1: Copy the nodes of the nut on surface 1 and project them onto the neutral layer of connected component 1 to form a shell mesh near the bolt holes of connected component 1. An additional washer can be added to the outer ring of these meshes.
[0011] C2. Establishing the bolt hole mesh of the connected component 2: Copy the nodes of the bolt head on surface 2 and project them onto the neutral layer of the connected component 2 to form a shell mesh near the bolt holes of the connected component 2. An additional washer can be added to the outer ring of these meshes.
[0012] D. After the bolt and nut solid meshes are engaged, a shell element is wrapped around them. The nodes between the shell and the solid element are engaged. Adjust the bolt, nut and shell meshes, taking into account the thickness, so that the gap between the shell mesh and the connected parts is zero.
[0013] E. Establish the connection relationship between bolts, nuts and connected parts. For welded nuts and welded bolts, establish a rigid connection between the welded nut or welded bolt and the connected parts according to the actual welding position. The mesh shape between the welded bolts and nuts and the connected parts is consistent, and the nodes correspond one-to-one.
[0014] F. Between connected parts, and between connected parts and bolts / nuts, use keywords to set force sensors. The force extracted by the force sensors after calculation can be used as a reference for the force on the bolts.
[0015] G. Create a DISCRETE element in the bolt. In step B, the bolt mesh contains two nodes, center 1 and center 2. Center 1 and center 2 are used as the two endpoints of the DISCRETE element. Create a DISCRETE element and assign it properties and material to extract bolt deformation and stress.
[0016] H. To apply preload to the bolt, to apply preload to a hexahedral solid mesh, you need to first create a loading surface using keywords. The loading surface is perpendicular to the bolt axis, passes through a row of solid elements, and the loading surface cannot pass through the bolt nodes.
[0017] I. Set the dynamic relaxation parameters;
[0018] J. Submit the calculation, and extract the results as needed after the calculation.
[0019] Further, in step A, the nut uses a hexahedral solid mesh, which should typically be less than 2.5mm, and ensure that there are at least three mesh layers in each direction.
[0020] Further, in step A, assign entity properties and material properties. If the material properties contain failure parameters, the bolt can be considered to fail in the simulation. The nut material is usually set to an elastoplastic material.
[0021] Further, in step B, the bolts are made of a hexahedral solid mesh, which should generally be less than 2.5mm, and ensure that there are at least three layers of mesh in each direction.
[0022] Further, in step B, the bolt is assigned entity properties and its actual material properties. If the material properties contain failure parameters, the bolt can be considered to fail in the simulation. In the small deformation region, and where the accuracy of bolt stress calculation is not high, the bolt can also be set as an elastic material.
[0023] Furthermore, in step C1, the mesh shapes of the nut and the connected part 1 are completely consistent on the contact surface, and the nodes can correspond one-to-one. However, note that the nodes between the connected part 1 and the nut do not mesh. The mesh of the connected part 1 can also be stretched into a solid mesh.
[0024] Further, in step C2, the mesh shape of the bolt head and the connected part 2 on the contact surface is completely consistent, and the nodes can correspond one-to-one. However, note that the nodes between the connected part 2 and the bolt head do not mesh. The mesh of the connected part 2 can also be stretched into a solid mesh. If there are more than two connected parts, the mesh near the bolt holes of the other connected parts has the same shape as the mesh near the bolt holes of the connected part 2, and the nodes can correspond one-to-one.
[0025] Further, in step E, a point-to-point rigid connection is made between the corresponding nodes. For non-welded bolts and non-welded nuts, the key is used to make contact between the shell and the connected parts. When the nut is made of rigid material, special treatment should be given. The nut and the connected parts 1 are connected.
[0026] Furthermore, in step H, if there is a gap between the bolts, nuts, and connected parts, the axial dimension of this row of units must be greater than the gap between the grids.
[0027] Further, in step H, the ratio of preload to bolt cross-sectional area is the prestress. Apply the corresponding prestress to the loading surface so that the entire bolt connection reaches its preload.
[0028] Compared with the prior art, the beneficial effects of the present invention are:
[0029] The bolt connection simulation analysis method of this invention can achieve a balance between precision and efficiency. It can be used for whole vehicle collision analysis models without significantly increasing the modeling workload and calculation time. At the same time, it can extract the overall stress and strain of the bolt, simulate bolt fracture, and guide the subsequent selection of bolt specifications. This method has high calculation accuracy and low consumption, and can extract the overall stress of the bolt, simulate bolt fracture, and guide the selection of bolt specifications. Attached Figure Description
[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0031] Figures 1a-1b Schematic diagram of bolted connection solid mesh;
[0032] Figure 2 Bolt connection diagram;
[0033] Figures 3a-3b The positions of center 1, center 2, and DISCRETE elements;
[0034] Figures 4a-4d Connected component mesh;
[0035] Figure 5 Schematic diagram of the loading surface. Detailed Implementation
[0036] The present invention will be further described below with reference to embodiments:
[0037] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.
[0038] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0039] This invention presents a simulation method for bolted connections, which utilizes hexahedral mesh elements to simulate bolted connections. Its innovations include: 1. Simulating the welding of nuts using a one-to-one node correspondence and a constrained_nodal_rigid_body connection; 2. Utilizing a composite simulation method of solid mesh bolts and DISCRETE elements to simulate bolted connections; 3. Establishing a loading surface using the database_cross_section keyword and applying preload using initial_stress_section; 4. Setting force sensors between connected components and between connected components and bolts / nuts using the force_transducer_penalty keyword; the force extracted by the force sensors after calculation can serve as a reference for bolt stress.
[0040] Specifically, the following steps are included:
[0041] The first step is to create a nut mesh and assign material properties. The nut uses a small hexahedral solid mesh, typically less than 2.5mm, and ensures at least three mesh layers in each direction. When creating the nut mesh, if the nut shape is complex, it can be divided into regions. Each region uses a shell element mesh stretched axially. When connecting different regions, the nodes correspond one-to-one and are meshed.
[0042] Assign entity and material properties. If the material properties include failure parameters, the bolt can be considered for failure in the simulation. Nut materials are typically set to elasto-plastic materials. To reduce solution resource consumption and computation time, nuts can also be assigned rigid or elastic materials.
[0043] The second step is to create the bolt mesh and assign material properties. Bolts use a small hexahedral solid mesh, typically below 2.5mm, ensuring at least three mesh layers in each direction. The bolt mesh creation method is similar to the nut mesh, dividing the mesh into regions and using a shell element mesh stretched axially. When connecting different regions of the bolt, the nodes correspond one-to-one and mesh. The mesh nodes on the contact surfaces of the bolt and nut also correspond one-to-one and mesh. The solid mesh for the bolt connection is shown in Figure 1. The contact surface between the nut and the connected parts is defined as surface 1, and the contact surface between the bolt head and the connected parts is defined as surface 2. Figure 2Create a node at the center of each circle on surface 1 and surface 2, namely center 1 and center 2, as shown in Figure 3. The bolt mesh should include these two nodes.
[0044] Assign solid properties and their actual material properties to the bolt. If the material properties include failure parameters, the bolt can be considered for failure in the simulation. In the small deformation region, and where the accuracy of bolt stress calculation is not critical, the bolt can also be set as an elastic material.
[0045] The third step is to create the mesh of the connected components and assign material properties. The mesh of the connected components is shown in Figure 4. The connected components can be divided into solid meshes or shell meshes, with special meshing required near the bolt holes. The method for creating the bolt hole mesh of connected component 1 is as follows: Copy the nodes of the nut on surface 1 and project them onto the neutral layer of connected component 1 to form a shell mesh near the bolt holes of connected component 1. A washer can be added to the outer ring of these meshes. The mesh shapes of the nut and connected component 1 are completely identical on the contact surface, and the nodes can correspond one-to-one. However, note that the nodes between connected component 1 and the nut do not mesh, as shown in Figure 4. The mesh of connected component 1 can also be extruded into a solid mesh. The method for creating the bolt hole mesh of connected component 2 is similar: copy the nodes of the bolt head on surface 2 and project them onto the neutral layer of connected component 2 to form a shell mesh near the bolt holes of connected component 2. A washer can be added to the outer ring of these meshes. The bolt head and the connected component 2 have completely identical mesh shapes on the contact surface, and the nodes can correspond one-to-one. However, note that the nodes between the connected component 2 and the bolt head do not mesh, as shown in Figure 4. The mesh of the connected component 2 can also be stretched into a solid mesh. If there are more than two connected components, the mesh shape near the bolt holes of the other connected components should be identical to the mesh shape near the bolt holes of the connected component 2, and the nodes should correspond one-to-one.
[0046] Assign actual materials and properties to the connected components.
[0047] Fourth, after the bolt and nut solid meshes are engaged, a shell element is wrapped around them, and the nodes between the shell and the solid elements are engaged. Adjust the bolt, nut, and shell meshes, taking into account the thickness, to ensure that the gap between the shell mesh and the connected parts is zero.
[0048] The shell unit is assigned the *mat_null material.
[0049] Step 5: Establish the connection relationships between bolts, nuts, and connected parts, as shown in Figure 4. For welded nuts and bolts, establish a rigid connection between the welded nut or bolt and the connected part based on the actual welding position. The mesh shape of the welded bolts and nuts is consistent with that of the connected parts, and the nodes correspond one-to-one. Typically, `constrained_nodal_rigidbody` is used to create a point-to-point rigid connection between the corresponding nodes. For non-welded bolts and nuts, the `automatic_surface_to_surface` keyword is used to create contact between the shell and the connected part. When the nut is made of a rigid material, special handling is required; the nut and connected part 1 are connected using `constrained_extra_nodes`.
[0050] The sixth step involves setting force sensors between connected components, and between connected components and bolts / nuts, using the `FORCE_TRANCEDUCER_PENALTY` keyword. The force extracted by the force sensors after calculation can then be used as a reference for the force on the bolts.
[0051] Step 7: Create a DISCRETE element in the bolt. In step 2, the bolt mesh contains two nodes, center 1 and center 2. Using center 1 and center 2 as the two endpoints of the DISCRETE element, create a DISCRETE element, as shown in Figure 3. Assign properties and material to the DISCRETE element. This is used to extract bolt deformation and stress.
[0052] Step 8: Apply preload to the bolt. To apply preload to the hexahedral solid mesh, a loading surface needs to be created using the `database_cross_section` keyword. This loading surface should be perpendicular to the bolt axis and pass through a row of solid elements. Note that the loading surface must not pass through the bolt nodes. See the loading surface diagram. Figure 5 Note that if there are gaps between the bolts, nuts, and connected parts that are not adjusted, the axial dimension of this row of elements must be larger than the gaps between the meshes to ensure that this row of elements will not have a negative volume after the bolt preload gaps are eliminated. The ratio of the preload force to the bolt cross-sectional area (calculated by the inner diameter) is the prestress. The corresponding prestress is applied to the loading surface through the initial_stress_section so that the entire bolted connection reaches its preload force.
[0053] Step 9: Set the dynamic relaxation parameters.
[0054] Step 10: Submit the calculation. Extract the results as needed after calculation.
[0055] Example 1
[0056] The first step is to create a nut mesh and assign material properties. The welded nut uses a hexahedral solid mesh with a target mesh size of 1mm and a maximum of 2mm. When creating the nut mesh, a shell element mesh is stretched axially. When connecting different regions, the nodes correspond one-to-one and are engaged, as shown in Figure 1.
[0057] The nut's properties are *element_solid, elform=2, aet=0. Select material number 24, and enter the material properties and failure parameters.
[0058] The second step is to create the bolt mesh and assign material properties. The bolts are represented by a hexahedral solid mesh with a target mesh size of 1m and a maximum of 2mm. The bolt mesh is created by dividing the mesh into regions, and within each region, shell element meshes are stretched axially. When connecting different regions of the bolt, the nodes correspond one-to-one and are interlocked. The mesh nodes of the bolt and nut contact surfaces also correspond one-to-one and are interlocked. The solid mesh for the bolt connection is shown in Figure 1. The contact surface between the nut and the connected parts is defined as surface 1, and the contact surface between the bolt head and the connected parts is defined as surface 2. Figure 2 Create a node at the center of each circle on surface 1 and surface 2, namely center 1 and center 2, as shown in Figure 3. The bolt mesh should include these two nodes.
[0059] The bolt properties are *element_solid, elform=2, aet=0. Select material number 24, and enter the material properties and failure parameters.
[0060] The third step is to create the mesh of the connected components and assign material properties. The mesh of the connected components is shown in Figure 4. All three connected components are 2mm thick and use shell element meshes, divided on a neutral layer. The mesh creation method for the bolt holes of connected component 1 is as follows: Copy the nodes of the nut on surface 1 and project them onto the neutral layer of connected component 1 to form a shell mesh near the bolt holes of connected component 1. Add a washer to the outer ring of these meshes. The mesh shapes of the nut and connected component 1 are completely identical on the contact surface, and the nodes can correspond one-to-one. However, note that the nodes between connected component 1 and the nut do not mesh, as shown in Figure 4. The mesh creation method for the bolt holes of connected component 2 is similar: copy the nodes of the bolt head on surface 2 and project them onto the neutral layer of connected component 2 to form a shell mesh near the bolt holes of connected component 2. Add a washer to the outer ring of these meshes. The bolt head and the connected part 2 have completely identical mesh shapes on the contact surface, and the nodes can correspond one-to-one. However, note that the nodes between the connected part 2 and the bolt head do not mesh, as shown in Figure 4. The mesh near the bolt hole of the connected part 3 is consistent with that of the connected part 2.
[0061] Assign the attribute *element_shell to the connected component, select material number 24, and enter the material properties and failure parameters.
[0062] Step 4: After the bolt and nut solid meshes are engaged, wrap them with a shell element. The shell and solid elements are then meshed at their nodes. The shell thickness is 1mm. Adjust the bolt and nut meshes, taking into account the thickness, to ensure that the gap between the bolt and the connected parts is zero, and the gap between the nut and the connected parts is also zero.
[0063] The shell unit is assigned *mat_null material.
[0064] Step 5: Establish the connection relationships between the bolts, nuts, and connected parts, as shown in Figure 4. The square weld nut needs to be welded to connected part 1. The mesh shape of the welded bolts and nuts is consistent with that of the connected parts, with nodes corresponding one-to-one. In Step 1, the weld nut is given an elasto-plastic material; therefore, `constrained_nodal_rigidbody` is used to create a point-to-point rigid connection between the corresponding nodes. Between the bolt head and connected part 2, the `automatic_surface_to_surface` keyword is used to establish contact between the shell and connected part 2.
[0065] Step 6: Set the force sensor between the bolt and the connected part 2 using the force_transducer_penalty keyword.
[0066] Step 7: Create a DISCRETE element in the bolt. In step 2, the bolt mesh contains two nodes, center 1 and center 2. Using center 1 and center 2 as the two endpoints of the DISCRETE element, create a DISCRETE element, as shown in Figure 3. Assign properties and material to the DISCRETE element. This is used to extract bolt deformation and stress.
[0067] Step 8: Apply preload to the bolts. To apply preload to the hexahedral solid mesh, a loading surface needs to be created using the `database_cross_section` keyword. The loading surface ID is 1, and it should be perpendicular to the bolt axis and pass through a row of solid elements. Note that the loading surface cannot pass through bolt nodes. The ratio of bolt preload to bolt cross-sectional area (calculated by inner diameter) is 500 MPa. Apply a 500 MPa prestress to the loading surface using `initial_stress_section` until the entire bolt connection reaches its preload. The loading curve is shown in Table 1. Set the parameter SIDR to 1, and select the aforementioned loading surface 1 with ID 1 for SECID.
[0068] Table 1
[0069] Time (ms) Stress (MPa) 0 0 10 500
[0070] Step 9: Set the dynamic relaxation parameters. In *control_dynamic_relection, set IRELAL and IDRFLG to 1.
[0071] Step 10: Submit the calculation. Extract the results as needed after calculation.
[0072] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.
Claims
1. A simulation method for bolted connections, characterized in that, Includes the following steps: A. Create a nut mesh and assign material properties: When creating a nut mesh, if the nut shape is complex, the mesh can be divided into regions. Each region uses a shell element mesh stretched along the axial direction. When connecting different regions, the nodes correspond one-to-one and mesh. B. Establishing the bolt mesh and assigning material properties: When establishing the bolt mesh, divide the mesh into regions and use the shell element mesh to stretch along the axial direction. When connecting the bolt regions, the nodes correspond one-to-one and mesh. The mesh nodes of the bolt and nut contact surfaces correspond one-to-one and mesh. When establishing the bolt connection solid mesh, define the contact surface between the nut and the connected part as surface 1, and the contact surface between the bolt head and the connected part as surface 2. Establish a node at the center of surface 1 and surface 2, namely center 1 and center 2. The bolt mesh should contain these two nodes. C. Create the mesh of the connected parts and assign material properties: The connected parts can be divided into solid meshes or shell meshes, and the mesh near the bolt holes needs to be specially divided. C1. Mesh creation for bolt holes of connected component 1: Copy the nodes of the nut on surface 1 and project them onto the neutral layer of connected component 1 to form a shell mesh near the bolt holes of connected component 1. An additional washer can be added to the outer ring of these meshes. C2. Establishing the bolt hole mesh of the connected component 2: Copy the nodes of the bolt head on surface 2 and project them onto the neutral layer of the connected component 2 to form a shell mesh near the bolt holes of the connected component 2. An additional washer can be added to the outer ring of these meshes. D. After the bolt and nut solid meshes are engaged, a shell element is wrapped around them. The nodes between the shell and the solid element are engaged. Adjust the bolt, nut and shell meshes, taking into account the thickness, so that the gap between the shell mesh and the connected parts is zero. E. Establish the connection relationship between bolts, nuts and connected parts. For welded nuts and welded bolts, establish a rigid connection between the welded nut or welded bolt and the connected parts according to the actual welding position. The mesh shape between the welded bolts and nuts and the connected parts is consistent, and the nodes correspond one-to-one. F. Between connected parts, and between connected parts and bolts / nuts, use keywords to set force sensors. The force extracted by the force sensors after calculation can be used as a reference for the force on the bolts. G. Create a DISCRETE element in the bolt. In step B, the bolt mesh contains two nodes, center 1 and center 2. Center 1 and center 2 are used as the two endpoints of the DISCRETE element. Create a DISCRETE element and assign it properties and material to extract bolt deformation and stress. H. To apply preload to the bolt, to apply preload to a hexahedral solid mesh, you need to first create a loading surface using keywords. The loading surface is perpendicular to the bolt axis, passes through a row of solid elements, and the loading surface cannot pass through the bolt nodes. I. Set the dynamic relaxation parameters; J. Submit the calculation, and extract the results as needed after the calculation.
2. The simulation method for bolted connections according to claim 1, characterized in that: Step A: The nut uses a hexahedral solid mesh, which should typically be less than 2.5mm, and ensure that there are at least three mesh layers in each direction.
3. The simulation method for bolted connections according to claim 1, characterized in that: Step A: Assign entity properties and material properties. If the material properties include failure parameters, the bolt can be considered for failure in the simulation. The nut material is usually set to an elastoplastic material.
4. The simulation method for bolted connections according to claim 1, characterized in that: Step B: The bolts should be made of a hexahedral solid mesh, which should generally be less than 2.5mm, and ensure that there are at least three layers of mesh in each direction.
5. The simulation method for bolted connections according to claim 1, characterized in that: Step B assigns entity properties and actual material properties to the bolt. If the material properties include failure parameters, the bolt can be considered to fail in the simulation. In the small deformation region, and where the accuracy of bolt stress calculation is not critical, the bolt can also be set as an elastic material.
6. The simulation method for bolted connections according to claim 1, characterized in that: In step C1, the mesh shapes of the nut and the connected part 1 are completely consistent on the contact surface, and the nodes can correspond one-to-one. However, note that the nodes between the connected part 1 and the nut do not mesh. The mesh of the connected part 1 can also be stretched into a solid mesh.
7. The simulation method for bolted connections according to claim 1, characterized in that: In step C2, the mesh shapes of the bolt head and the connected part 2 are completely consistent on the contact surface, and the nodes can correspond one-to-one. However, note that the nodes between the connected part 2 and the bolt head do not mesh. The mesh of the connected part 2 can also be stretched into a solid mesh. If there are more than two connected parts, the mesh shape near the bolt holes of the other connected parts is consistent with the mesh shape near the bolt holes of the connected part 2, and the nodes can correspond one-to-one.
8. The simulation method for bolted connections according to claim 1, characterized in that: Step E: A point-to-point rigid connection is made between the corresponding nodes. For non-welded bolts and non-welded nuts, the key is used to make contact between the shell and the connected parts. When the nut is made of rigid material, special treatment should be given. The nut and the connected parts 1 are connected.
9. The simulation method for bolted connections according to claim 1, characterized in that: In step H, if there are gaps between the bolts, nuts, and connected parts, the axial dimension of this row of units must be greater than the gap between the grids.
10. The simulation method for bolted connections according to claim 1, characterized in that: Step H: The ratio of preload to bolt cross-sectional area is the prestress. Apply the corresponding prestress to the loading surface so that the entire bolt connection reaches its preload.