Rapid modeling method for refined rubber-riveted joint numerical simulation model

Abstract

The invention discloses a refined rubber-riveted joint numerical simulation model rapid modeling method, which comprises the following steps: mapping grid nodes near boundaries in a rubber-riveted joint forming process simulation result to a left or right boundary, rotating around a Y axis to stretch a two-dimensional grid between the left and right boundaries to obtain a three-dimensional solid grid, filling a vacant area formed by rotation of the left boundary, and forming a rubber-riveted joint. Obtaining a fine grid area grid model; according to the plate thickness combination, corresponding grid models in the coarse grid model library are extracted, the positions of the grid models are adjusted, and a coarse grid model of the glue-riveted joint is obtained; according to the grid density in the thickness direction of the coarse grid area and the fine grid area, a transition area grid is constructed at the right boundary of the fine grid area grid model, the transition area grid and the coarse grid model share the same node, and a glue riveted joint grid model is obtained; stress-strain field information in a simulation result in the forming process is mapped into a rubber-riveted joint grid model; and defining the contact between the rivet and the blanking, the contact between the rivet and the upper-layer plate and the contact between the rivet and the plate, and simulating an adhesive layer to obtain a refined numerical simulation model of the adhesive-riveted joint.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of glue-riveted joint simulation modeling, and particularly relates to a fast modeling method of a fine glue-riveted joint numerical simulation model. BACKGROUND

[0002] Self-piercing riveting connection technology, as a cold connection technology, can realize the connection between the same and different materials, and is widely used in multi-material vehicle bodies due to the advantages of simple process, high connection efficiency and stable joint strength. Adding structural glue to the self-piercing riveting joint can improve the strength thereof. In order to study the mechanical properties of glue-riveted joints of different material and plate thickness combinations, the experimental test method is generally used. However, the experimental method has the disadvantages of long time consumption and high cost, especially when the sample quantity is large.

[0003] With the improvement of computer performance, the method of constructing a 3D fine simulation model of a glue-riveted joint by using finite element simulation has become another method for studying the mechanical properties thereof. However, the existing modeling method has the disadvantages of complicated operation and long modeling time, and is not suitable for modeling of a large number of samples. Moreover, the 3D fine model constructed thereby does not accurately consider the influence of residual stress and strain of the glue-riveting forming process. SUMMARY

[0004] The application provides a fast modeling method of a fine glue-riveted joint numerical simulation model, and aims to solve the problems of low modeling efficiency of the existing fine glue-riveted joint numerical simulation model when a large number of samples are needed, and the problem that the fine glue-riveted joint numerical simulation model cannot accurately represent the actual mechanical response under dynamic load conditions.

[0005] A fast modeling method of a fine glue-riveted joint numerical simulation model comprises the following steps:

[0006] The glue-riveted joint is divided into a coarse grid area, a fine grid area and a transition area according to the profile of the glue-riveted joint;

[0007] The coordinate origin of the modeling software is selected as a reference point, and a coarse grid model library of different plate thicknesses and different test conditions is constructed;

[0008] The glue-riveted joint forming simulation is defined as a problem of axial symmetry plane strain about the Y-axis of the modeling software coordinate system, and the glue-riveted joint forming process simulation of a given material and thickness combination is carried out;

[0009] The left boundary is defined as a distance R1 from the Y-axis of the modeling software coordinate system, and the right boundary is defined as a distance R2 from the Y-axis of the modeling software coordinate system, wherein R2>R1;

[0010] The grid nodes near the boundary in the simulation result of the rivet joint forming process are mapped to the left boundary or the right boundary, the two-dimensional grid between the left and right boundaries is rotated around the Y axis to obtain a three-dimensional entity grid, the vacancy area formed by the rotation of the left boundary is filled by stretching the plane grid to obtain a fine grid area grid model;

[0011] According to the thickness combination of the rivet joint plate, the corresponding grid model in the coarse grid model library is extracted and adjusted in position to obtain a coarse grid model of the rivet joint;

[0012] According to the grid density in the thickness direction of the coarse and fine grid areas, the transition area grid is constructed by using a scheme combination method at the right boundary of the fine grid area grid model, and is shared with the coarse grid model to obtain a rivet joint grid model;

[0013] The stress and strain field information in the simulation result of the forming process is mapped to the rivet joint grid model by using the volume intersection method;

[0014] The rivet and the blank are defined as a binding contact, the rivet and the upper plate are defined as a surface-to-surface contact, and the plates are defined as a binding contact with failure, the adhesive layer is simulated, and a refined numerical simulation model of the rivet joint is obtained for evaluating the mechanical properties of the rivet joint.

[0015] Further, the fine grid area includes the rivet, the blank, and part of the upper plate, the adhesive layer, and the lower plate; the coarse grid area includes the clamp and the remaining part of the upper plate, the adhesive layer, and the lower plate; and the transition area is a part connecting the fine grid area and the coarse grid area.

[0016] Further, the coarse grid model library specifically includes:

[0017] The grid models of the upper and lower plates in each test condition are placed at the coordinate origin, and the coordinate origin is used as the reference point of the grid models in each test condition; the upper and lower plates in each test condition are constructed as a through hole with a radius of R3 around the Y axis to obtain a coarse grid area of the plate; the circumferential grid density of the through hole is controlled to be consistent with the number of rotations u when generating the three-dimensional grid of the rivet; the surface of the area where the adhesive layer of the upper and lower plates is located is composed of radially arranged grids about the Y axis; the surface grids of the upper and lower plates are stretched in the thickness direction according to each test condition to obtain the three-dimensional entity grid of the coarse grid area plate; the grid model of the clamp is constructed by using a hexahedral grid; wherein R3>R2, R3 represents both the radius of the through hole and the outer radius of the transition area, and R2 represents both the outer radius of the fine grid area and the inner radius of the transition area;

[0018] The finite element models of the adhesive layer and the clamp are established;

[0019] Create the model's main file, control file, and material file. The main file is the input file for the simulation. The control file defines the constraints and loads, and the material file defines the material parameters of each component of the model.

[0020] Repeat the above steps to create coarse mesh models of glued joints with different thicknesses and material combinations, thus forming a coarse mesh model library.

[0021] Furthermore, fill the empty area created by rotating the left boundary, as follows:

[0022] Construct a planar mesh in the XOZ plane of the modeling software: Let u be the number of rotations when generating the rivet 3D mesh, and add (u / 8+1) at equal intervals within the range of x∈[0, cR1] and z∈[0, cR1]. 2 There are 8 nodes, and (u / 8) are generated from these nodes. 2 A square grid is generated; (u / 8+1) nodes are added at equal intervals on the coordinate axes within the range of x∈[cR1, R1] and z∈[cR1, R1]. Two (u / 8+1) nodes are taken at equal intervals on the arc of the circle in the first quadrant R=R1. These nodes are connected to the outer nodes of the square grid to form the grid for the remaining part of the first quadrant, where c represents a constant used to control the grid size in the XOZ plane of the modeling software; and so on, generating grids for other quadrants to form a circular region planar grid with radius R1.

[0023] Before stretching the planar mesh, determine the component to which it belongs using the following method: Sort the nodes of each part at the left and right boundaries in a top-down order. If the i-th node belongs to component 1, the (i+1)-th node belongs to component 2, and the (i+2)-th node also belongs to component 2, there is no penetration phenomenon. Stretch the planar mesh of the central circular area of ​​each component normally in this order. If the i-th node belongs to component 1, the (i+1)-th node belongs to component 2, and the (i+2)-th node belongs to component 1, there is a penetration phenomenon. Rename the original (i+2)-th node belonging to component 1 to i+1, and the original (i+1)-th node belonging to component 2 to i+2. Stretch the planar mesh of the central circular area of ​​each component in the reversed order.

[0024] Based on the judgment results, the planar mesh of the above circular area is stretched along the Y-axis to form a three-dimensional mesh of the cylinder in the middle of each component. The mesh of the adhesive layer does not need to be stretched.

[0025] Furthermore, the method for adjusting the position is as follows: based on the thickness parameters of the sheet, and taking the center of the adhesive layer from the simulation results of the forming process as the reference, the nodes of the upper and lower plates and the fixture are translated in the Y-axis direction so that the upper and lower plates and the fixture are in a position parallel to the outside of the transition layer; at the same time, the clamping end of the fixture moves relative to the reference to simulate the clamping situation in the experiment.

[0026] Further, the moving method of the upper and lower plates and the clamp is: defining the thickness of the upper plate as T t , the thickness of the lower plate as T l , and the thickness of the glue layer as T g , then the moving distance D t of the upper plate, the moving distance D l of the lower plate, the moving distance D t1 of the upper clamp, the moving distance D t2 of the upper clamping end, the moving distance D l1 of the lower clamp, and the moving distance D l2 of the lower clamping end are expressed by the following formula:

[0027]

[0028] Further, the construction method of the transition zone grid is: constructing m transition layers to realize the transition of the plate thickness direction from the fine grid zone with a grid density of A to the coarse grid zone with a grid density of Z, each transition layer is composed of different transition schemes, the transition scheme refers to a certain unit combination that can realize the transition of p units to q units, wherein m≥1, A>Z, and p>q.

[0029] Further, assuming that the transition scheme n transitions p n units to q n units, the number of transition scheme 1 constituting the first transition layer is x 11 , the number of transition scheme 2 constituting the first transition layer is x 12 , …, the number of transition scheme n constituting the mth transition layer is x mn ; the first transition layer transitions A units to B units, the second transition layer transitions B units to C units, …, the mth transition layer transitions Y units to Z units, wherein A>B>C>…>Y>Z, and:

[0030]

[0031] Further, the stress and strain field information mapping method is: obtaining the stress and strain of the solid element through linear interpolation of the spatial relationship between the solid elements; using the number of intersection points between the elements to represent the spatial relationship between the solid elements, thereby obtaining the stress and strain P N , P N representing N original elements containing stress and strain information; taking S0 uniformly distributed points in each element, and the stress of each element is represented as σ N ; Q represents a target element that needs to be mapped, when a target element is at any position in space, it may intersect with N original elements in volume, assuming that the number of intersection points is S N , then the stress σQ satisfies:

[0032] Further, the Mth partial adhesive layer thickness T is calculated using a quadratic interpolation polynomial gM and the contact tangential failure stress σ sM , the contact normal failure stress σ n’M , and the relationship for simulating the strength of the adhesive layer:

[0033]

[0034] where a k and b k are coefficients, σ s0 represents the calibrated contact tangential failure stress, and σ n’0 represents the calibrated contact normal failure stress.

[0035] Compared with the prior art, the beneficial effects of the present application are:

[0036] (1) The present application is based on a coarse mesh model library, and the models in the coarse mesh model library can be expanded according to the thickness of the plate and the material requirements under different working conditions. When modeling, only the adhesive rivet joint forming process simulation of the given material and thickness combination needs to be carried out, and the necessary parameters can be input to complete the rapid modeling of the adhesive rivet joint numerical simulation model. Most of the operations have been realized through programming, and the modeling process has been simplified as much as possible.

[0037] (2) When the same adhesive rivet process is used to connect the same upper plate and lower plate, the numerical simulation model of the adhesive rivet joint with different rivet point positions or structural forms can be realized by replacing the fine mesh region model. The more the number of such joints, the more significant the advantages of the rapid modeling of the present application.

[0038] (3) Considering the influence of residual stress and strain in the adhesive rivet joint forming process, the stress and strain field information of the two-dimensional forming simulation results of the adhesive rivet joint is mapped into the three-dimensional mesh model of the adhesive rivet joint, improving the accuracy of the numerical simulation model of the adhesive rivet joint. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the present application will be described in detail below with reference to the drawings and detailed embodiments, in which:

[0040] Figure 1 is a flow chart of a rapid modeling method of a fine adhesive rivet joint numerical simulation model;

[0041] Figure 2 is a structural profile view of an adhesive rivet joint;

[0042] Figure 3 is a rivet joint mesh region division diagram;

[0043] Figure 4 Fig. 1 is a diagram of a fine mesh area numerical simulation model of a glue-riveted joint;

[0044] Figure 5 Fig. 2 is a diagram of a joint under cross tensile working condition;

[0045] Figure 6 Fig. 3 is a diagram of a joint under peeling working condition;

[0046] Figure 7 Fig. 4 is a diagram of a joint under shearing working condition;

[0047] Figure 8 Fig. 5 is a diagram of a cross tensile clamp;

[0048] Figure 9 Fig. 6 is a transition layer scheme adopted in the embodiment;

[0049] Figure 10 Fig. 7 is a comparison result diagram of load-displacement curves of cross tensile joint test and simulation;

[0050] Figure 11 Fig. 8 is a comparison result diagram of load-displacement curves of peeling joint test and simulation;

[0051] Figure 12 Fig. 9 is a comparison result diagram of load-displacement curves of shearing joint test and simulation. DETAILED DESCRIPTION

[0052] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0053] As shown in Figure 1 , the embodiment of the present application discloses a fast modeling method of a fine glue-riveted joint numerical simulation model, and the specific steps are as follows:

[0054] S1, the glue-riveted joint is divided into a coarse mesh area, a fine mesh area and a transition area between the two by the cross-sectional morphology of the glue-riveted joint;

[0055] S2, the coordinate origin of the modeling software (running in the computer) is selected as the reference point, and a coarse mesh model library of different plate thicknesses and different test working conditions is constructed;

[0056] S3, the glue-riveted joint forming simulation is defined as an axisymmetric plane strain problem about the Y-axis coordinate system of the modeling software, and the glue-riveted joint forming process simulation of a given material and thickness combination is carried out;

[0057] S4, define the left boundary at R1 and the right boundary at R2 (R2>R1) of the Y-axis of the distance modeling software coordinate system;

[0058] S5, map the grid nodes near the boundary in the simulation results of the glue rivet joint forming process to the corresponding boundary (left boundary or right boundary), rotate and stretch the two-dimensional grid between the left and right boundaries around the Y-axis to obtain a three-dimensional entity grid, and fill the vacancy area formed by the rotation of the left boundary by stretching the plane grid to obtain a fine grid area grid model;

[0059] S6, according to the thickness combination of the glue rivet joint plate (upper or lower plate), extract the corresponding grid model from the coarse grid model library and adjust its position to obtain a coarse grid model of the glue rivet joint;

[0060] S7, according to the grid density in the thickness direction of the coarse and fine grid areas, construct the transition area grid at the right boundary of the fine grid area grid model using the scheme combination method, and share nodes with the coarse grid model to obtain a glue rivet joint grid model;

[0061] S8, map the stress and strain field information in the simulation results of the forming process to the glue rivet joint grid model by the volume intersection method;

[0062] S9, define the Tie (binding) contact between the rivet and the blank, the face-face contact between the rivet and the upper plate, and the Tiebreak (binding with failure) contact between the plates, simulate the glue layer, and obtain a refined glue rivet joint numerical simulation model for evaluating the mechanical properties of the glue rivet joint.

[0063] In the step S1, Figure 2 The glue rivet joint profile includes the following parts: rivet, upper plate, lower plate, blank, and glue layer. Figure 3 As shown, the glue rivet joint is divided into three areas: the fine grid area is the center part of the glue rivet joint (including the rivet, the blank, and part of the upper plate, the glue layer, and the lower plate), the coarse grid area is the plate (the remaining part of the upper plate, the glue layer, and the lower plate) and the clamp, and the transition area connects the fine grid area and the coarse grid area. The transition area is composed of multiple transition layers from dense to sparse, and the unit composition of the transition area is determined based on the scheme combination method according to the number of units on the high grid density side and the low grid density side.

[0064] In the step S2, the coarse grid model library includes model grid files, main files, control files, and material files. When the actual test working condition parameters are input, the automatic modeling software can realize rapid modeling by moving the grid file to the required position of each working condition, and output the three-dimensional coarse grid simulation model of each test working condition. The specific steps of building the coarse grid model library are as follows:

[0065] S2.1, establish as Figure 5 ,6 The mesh model shown in Figure 7: The mesh models of the upper and lower plates for each test condition are placed at the origin of the coordinate system, with the origin serving as the reference point for the mesh models of each test condition; for each test condition, the upper and lower plates have through holes with a radius of R3 constructed around the Y-axis to obtain the coarse mesh region of the plate; the circumferential mesh density of the through holes is controlled to be consistent with the rotation factor u when generating the 3D mesh of the rivet; the surface of the area where the adhesive layer of the upper and lower plates is located is composed of a mesh that radiates about the Y-axis; according to each test condition, the surface mesh of the upper and lower plates is stretched along the thickness direction to obtain the 3D solid mesh of the plate in the coarse mesh region; the mesh model of the fixture is constructed using a hexahedral mesh; where R3 > R2, R3 represents both the radius of the through hole and the outer radius of the transition zone, and R2 represents both the outer radius of the fine mesh region and the inner radius of the transition zone;

[0066] S2.2, Establish the finite element model of the adhesive layer and the fixture;

[0067] S2.3, create the model master file, control file, and material file. The master file is the input file for the simulation. The control file defines the constraints and loads, and the material file defines the material parameters of each component of the model.

[0068] S2.4 Repeat the above steps to create coarse mesh models of glued joints with different thicknesses and material combinations, forming a coarse mesh model library.

[0069] In step S3, the geometric feature information of the simulation results of the forming process of the glued riveting joint is used to compare with the cross-sectional test of the glued riveting joint to verify the accuracy of the numerical simulation of the forming process of the 2D glued riveting joint; the stress and strain field information of the simulation results of the forming process of the glued riveting joint is used as input for the subsequent mapping of the numerical simulation model of the 3D glued riveting joint.

[0070] In step S5, the specific steps for filling the empty area formed by rotating the left boundary are as follows:

[0071] S5.1, Construct the planar mesh in the XOZ plane of the modeling software: Let u be the number of rotations when generating the rivet 3D mesh, and add (u / 8+1) at equal intervals within the range of x∈[0, cR1] and z∈[0, cR1]. 2 There are 8 nodes, and (u / 8) are generated from these nodes. 2A square grid is generated; (u / 8+1) nodes are added at equal intervals on the coordinate axes within the range of x∈[c R1, R1] and z∈[c R1, R1]. Two (u / 8+1) nodes are also added at equal intervals on the arc of the circle in the first quadrant R=R1. These nodes are connected to the outer nodes of the square grid to form the remaining grid in the first quadrant, where c represents a constant used to control the grid size in the XOZ plane of the modeling software. This process is repeated to generate grids in other quadrants, forming a circular planar grid with a radius of R1. In this embodiment, c=0.4.

[0072] S5.2 Before stretching the above planar mesh, determine the component it belongs to using the following method:

[0073] Considering the penetration problem of nodes on the left and right boundaries of the rivet joint at the junctions of different parts, the nodes of each part at the left and right boundaries are sorted in a top-down order. If the i-th node belongs to component 1, the (i+1)-th node belongs to component 2, and the (i+2)-th node also belongs to component 2, there is no penetration phenomenon, and the planar mesh of the central circular area of ​​each component is stretched normally in this order. If the i-th node belongs to component 1, the (i+1)-th node belongs to component 2, and the (i+2)-th node belongs to component 1, then a penetration phenomenon occurs, and the nodes need to be renumbered. Let the original (i+2)-th node belonging to component 1 be numbered i+1, and the original (i+1)-th node belonging to component 2 be numbered i+2, and the planar mesh of the central circular area of ​​each component be stretched in the reversed order.

[0074] S5.3, based on the judgment result, the planar mesh of the above-mentioned circular area is stretched along the Y-axis to form a cylindrical three-dimensional mesh in the middle of each component. The mesh of the adhesive layer does not need to be stretched; thus obtaining the following... Figure 4 The complete fine-mesh area mesh model is shown.

[0075] In step S6, the position adjustment is performed as follows: based on the thickness parameters of the sheet metal, and using the center of the adhesive layer from the forming process simulation results as a reference, the nodes of the upper and lower plates and the fixture are translated along the Y-axis, so that the upper and lower plates and the fixture are in a position parallel to the outer side of the transition layer; simultaneously, the clamping end of the fixture is moved relative to the reference to simulate the clamping situation in the experiment. The method for moving the upper and lower plates and the fixture is as follows: the thickness of the upper plate is defined as T. t The thickness of the lower plate is T. l The adhesive layer thickness is T g Then the upper plate moves a distance D t The lower plate moving distance D l The moving distance D of the upper clamp t1 The moving distance D of the upper clamping end t2 The moving distance D of the lower clamp l1 The moving distance D of the lower clamping end l2Expressed using equation (1.1):

[0076]

[0077] In step S7, the transition zone mesh construction method is as follows:

[0078] Construct m (m≥1) transition layers to achieve the transition along the thickness direction of the plate from a fine mesh region with mesh density A to a coarse mesh region with mesh density Z (A>Z). Each transition layer is composed of a combination of different transition schemes. A transition scheme refers to a certain combination of elements that can transition p elements to q elements (p>q). Let transition scheme n transition p elements to q elements. n Each unit transitions to q n x units; the number of transition scheme 1 constituting the first transition layer is x. 11 The number of transition schemes 2 constituting the first transition layer is x. 12 ...the number of transition schemes that constitute the m-th transition layer is x. mn The first transition layer transitions A units to B units, the second transition layer transitions B units to C units, and so on, until the m-th transition layer transitions Y units to Z units (A>B>C>…>Y>Z). The above variables satisfy the relationship in equation (1.2):

[0079]

[0080] In step S8, the method for mapping stress-strain field information is as follows: the stress and strain of the solid elements are obtained by linear interpolation of the spatial relationship between solid elements; in practical applications, to improve computational efficiency, the number of intersection points between elements is used to characterize the spatial relationship between solid elements, thereby obtaining the stress and strain P of the solid elements. N (N = 1, 2, 3…) represents N original elements containing stress and strain information. S0 uniformly distributed points are taken in each element, and the stress in each element is expressed as σ. N Let Q represent the target element to be mapped. When a target element is at any position in space, it may intersect N original elements in volume. Let S be the number of points of intersection. n Then the stress σ of the target element Q Q It can be expressed by equation (1.3):

[0081]

[0082] In S9, using

[0083] *CONTACT_AUTOMATIC_ONE_WAY_SURFACE_TO_SURFACE_TIEBREAK represents the adhesive layer in the rivet joint, *CONTACT_AUTOMATIC_SURFACE_TO_SURFACE represents the contact between the rivet and the upper and lower plates, and *CONTACT_TIED_SURFACE_TO_SURFACE represents the contact between the rivet and the blank.

[0084] The thickness of the adhesive layer in the rivet joint is unevenly distributed at various locations. Therefore, the adhesive layer is divided into M parts according to the rule that the thickness is approximately the same. In this embodiment, the thickness T of the adhesive layer in the Mth part is calculated using quadratic interpolation polynomials (1.4) and (1.5). gM Contact tangential failure stress σ sM Normal failure stress σ n’M The relationship is used to simulate the strength of the adhesive layer, where σ s0 This represents the calibrated contact tangential failure stress, σ. n’0 Indicates the calibrated contact normal failure stress:

[0085]

[0086]

[0087] Among them, a k b k (k = 0, 1, 2...) are coefficients.

[0088] The form of the interpolation function mentioned above is not limited to a polynomial interpolation function. The type of interpolation function depends on the specific fitting relationship between the adhesive layer thickness and strength.

[0089] Example:

[0090] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be described in complete and clear form below with reference to the accompanying drawings:

[0091] Given the dimensions of the base material under cross-tension, shear, and peel conditions, as follows: Figure 5 , 6 As shown in Figure 7, based on this dimension, a coarse mesh model of the parent material and fixture under each working condition is established with the coordinate origin of the modeling software as the center, and boundary conditions are applied, and control cards and material cards are added.

[0092] The forming simulation of the glued riveting joint is simplified into a plane strain problem with respect to the Y-axis coordinate system of the modeling software. The forming process of the glued riveting joint is simulated with the upper plate material being HC340 with a thickness of 1 mm and the lower plate material being 5182 with a thickness of 1 mm. The two-dimensional forming simulation results of the glued riveting joint containing stress and strain field information are obtained.

[0093] Define R1 = 0.4mm as the left boundary of the above two-dimensional forming simulation result of the adhesive riveting joint, and R2 = 9mm as the right boundary of the above two-dimensional forming simulation result of the adhesive riveting joint. Rotate and extrude the two-dimensional mesh within the left and right boundaries around the Y-axis into 80 parts to obtain a three-dimensional solid mesh. Construct a planar mesh and extrude it to fill the empty area formed by rotating the left boundary; the number of meshes on the circumference of this planar mesh is also 80, and the component to which the mesh belongs is determined during extrusion.

[0094] Based on the thickness of the upper and lower layers and the adhesive layer, move the base material and clamps in the coarse mesh area to position them correctly.

[0095] A matching transition layer scheme is used to establish a mesh model for the transition zone. This embodiment adopts... Figure 9 The dual transition layer scheme shown connects the coarse mesh region and the fine mesh region. By sharing nodes between the coarse mesh region and the transition region, the mesh model of the adhesive riveting joint is obtained.

[0096] The stress-strain field information of the two-dimensional forming simulation results of the adhesive riveting joint is mapped onto the mesh model of the adhesive riveting joint in the three-dimensional fine mesh region.

[0097] The adhesive layer in the rivet joint is characterized by *CONTACT_AUTOMATIC_ONE_WAY_SURFACE_TO_SURFACE_TIEBREAK, *CONTACT_AUTOMATIC_SURFACE_TO_SURFACE is used to characterize the contact between the rivet and the upper and lower plates, and *CONTACT_TIED_SURFACE_TO_SURFACE is used to characterize the contact between the rivet and the blank. The contact strength of the adhesive layer is defined by the following formula:

[0098]

[0099] At this point, the refined numerical simulation model of the glued joint under cross-tension, peeling, and shearing conditions has been completed. Mesh rotation and stretching, the establishment of the transition zone, and the mapping of stress and strain field information have all been implemented through programming, significantly improving modeling efficiency.

[0100] Table 1 lists the thickness and material information of the upper and lower plates for the three types of joints.

[0101] Table 1. Materials and Plate Thickness of Adhesive Rivet Joints

[0102]

[0103] Table 2 Comparison of Peak Loads of Adhesive Rivet Joints under Dynamic Loading

[0104]

[0105] Table 3 Comparison and Analysis of Modeling Time for Adhesive Rivet Joints

[0106]

[0107] Table 2 shows the comparison results of peak loads of the glued riveting joint under dynamic load conditions between experiments and simulations. The peak loads of the conventional glued riveting joint numerical simulation model are much smaller than the experimental results, with errors of -23.8%, -20.5%, and -12.4%, respectively, all greater than 10%. However, the peak loads predicted by the refined glued riveting joint numerical simulation model of this invention are controlled at 4.7%, -1.2%, and -4.91%, respectively.

[0108] Table 3 shows a comparative analysis of the modeling time required by the present invention and conventional modeling methods for establishing refined numerical simulation models of glued riveted joints with different numbers of models. The modeling time varies for different joint types, riveting point locations, and structural forms. Table 3 shows that the present invention has an advantage when the number of joint models is small, but this advantage diminishes when the number of joint models increases to 10. 2 When the scale reaches the order of magnitude, the advantages of this invention in rapid modeling become fully apparent.

[0109] Figure 10 , 11 Figures 1 and 12 represent the comparison results of the load-displacement curves of the adhesive riveting joint in experiments and simulations under cross-tension, peeling, and shearing conditions. As shown in the figures, the load-displacement curves of the refined numerical simulation model of the adhesive riveting joint of this invention are highly consistent with the experimental results, and can simulate the mechanical properties of the adhesive riveting joint under cross-tension, peeling, and shearing conditions.

[0110] In summary, the rapid modeling method for refined numerical simulation models of glued riveting joints proposed in this invention can more accurately simulate the mechanical response of glued riveting joints and the morphology at failure. Furthermore, the rapid modeling advantage of this invention is significant when a large number of joint models are required. This indicates that in glued riveting connection research, the method of this invention can well meet the need for establishing a large number of refined numerical simulation models of glued riveting joints.

[0111] The above description provides a brief overview of the present invention and is not limited to the scope of work described above. Any simple modifications made to the ideas and methods of the present invention for use in other devices, or any improvements and refinements made without changing the main conceptual principles of the present invention, are all within the protection scope of the present invention.

Claims

1. A rapid modeling method for a refined numerical simulation model of a glued joint, characterized in that: Based on the cross-sectional morphology of the adhesive riveting joint, the joint is divided into a coarse mesh area, a fine mesh area, and a transition area. The origin of the modeling software was selected as the reference point to construct a coarse mesh model library with different plate thicknesses and different test conditions. The forming simulation of the glued riveting joint is defined as an axisymmetric plane strain problem about the Y-axis coordinate system of the modeling software, and the forming process of the glued riveting joint with a given combination of materials and thicknesses is simulated. Define the left boundary at point R1 on the Y-axis of the distance modeling software coordinate system and the right boundary at point R2 on the Y-axis of the distance modeling software coordinate system, where R2>R1; In the simulation results of the forming process of the glued joint, the mesh nodes near the boundary are mapped to the left or right boundary. The two-dimensional mesh between the left and right boundaries is rotated and stretched around the Y-axis to obtain a three-dimensional solid mesh. The empty area formed by the rotation of the left boundary is filled by stretching the planar mesh to obtain the fine mesh area mesh model. Based on the thickness combination of the adhesive riveting joint plates, the corresponding mesh model in the coarse mesh model library is extracted and its position is adjusted to obtain the coarse mesh model of the adhesive riveting joint. Based on the mesh density in the thickness direction of the coarse and fine mesh regions, a transition zone mesh is constructed at the right boundary of the fine mesh region mesh model using a combination of methods, and shares nodes with the coarse mesh model to obtain the glued joint mesh model. The stress and strain field information from the simulation results of the forming process is mapped onto the mesh model of the glued joint using the volume intersection method. The contact between the rivet and the blank is defined as a binding contact, the contact between the rivet and the upper plate is a surface-to-surface contact, and the contact between the plates is a binding contact with failure. By simulating the adhesive layer, a refined numerical simulation model of the adhesive riveting joint is obtained, which is used to evaluate the mechanical properties of the adhesive riveting joint.

2. The rapid modeling method for refined numerical simulation model of glued joints according to claim 1, characterized in that, The fine mesh area includes the rivets, blanking, and parts of the upper and lower layers; the coarse mesh area includes the fixtures and the remaining parts of the upper and lower layers; the transition area is the part connecting the fine mesh area and the coarse mesh area.

3. The rapid modeling method for refined numerical simulation models of adhesive riveting joints according to claim 1, characterized in that, The coarse mesh model library is as follows: The mesh models of the upper and lower plates for each test condition are placed at the origin of the coordinate system, with the origin serving as the reference point for the mesh models of each test condition. For each test condition, through holes with a radius of R3 are constructed on the upper and lower plates with the Y-axis as the axis, resulting in a coarse mesh region for the plate. The circumferential mesh density of the through holes is controlled to be consistent with the rotation factor u when generating the 3D mesh of the rivets. The surface of the adhesive layer area on the upper and lower plates is composed of a radial mesh about the Y-axis. According to each test condition, the surface mesh of the upper and lower plates is stretched along the thickness direction to obtain a 3D solid mesh of the plate in the coarse mesh region. A hexahedral mesh is used to construct the mesh model of the fixture. R3 > R2, where R3 represents both the radius of the through hole and the outer radius of the transition zone, and R2 represents both the outer radius of the fine mesh region and the inner radius of the transition zone. Finite element models of the adhesive layer and the fixture are established. Create a main model file, a control file, and a material file. The main file is the input file for the simulation. Define constraints and loads in the control file and define the material parameters of each component in the material file. Repeat the above steps to create coarse mesh models of glued joints with different thicknesses and material combinations, thus forming a coarse mesh model library.

4. The rapid modeling method for refined numerical simulation model of glued joints according to claim 3, characterized in that, Fill the empty area created by rotating the left boundary, as follows: Construct a planar mesh in the XOZ plane of the modeling software: Let u be the number of rotations when generating the 3D mesh of the rivets, and add (u / 8+1) at equal intervals within the range of x∈[0, cR1] and z∈[0, cR1]. 2 There are 8 nodes, and (u / 8) are generated from these nodes. 2 A square grid is generated; (u / 8+1) nodes are added at equal intervals on the coordinate axes within the range of x∈[cR1, R1] and z∈[cR1, R1]. Two (u / 8+1) nodes are taken at equal intervals on the arc of the circle in the first quadrant R=R1. These nodes are connected to the outer nodes of the square grid to form the grid for the remaining part of the first quadrant, where c represents a constant used to control the grid size in the XOZ plane of the modeling software; and so on, generating grids for other quadrants to form a circular region planar grid with radius R1. Before stretching the planar mesh, determine the component to which it belongs using the following method: Sort the nodes of each part at the left and right boundaries in a top-down order. If the i-th node belongs to component 1, the (i+1)-th node belongs to component 2, and the (i+2)-th node also belongs to component 2, there is no penetration phenomenon. Stretch the planar mesh of the central circular area of ​​each component normally in this order. If the i-th node belongs to component 1, the (i+1)-th node belongs to component 2, and the (i+2)-th node belongs to component 1, there is a penetration phenomenon. Rename the original (i+2)-th node belonging to component 1 to i+1, and the original (i+1)-th node belonging to component 2 to i+2. Stretch the planar mesh of the central circular area of ​​each component in the reversed order. Based on the judgment results, the planar mesh of the above circular area is stretched along the Y-axis to form a cylindrical three-dimensional mesh in the middle of each component. The mesh of the adhesive layer does not need to be stretched.

5. The rapid modeling method for refined numerical simulation model of glued joints according to claim 1, characterized in that, The method for adjusting the position is as follows: based on the thickness parameters of the sheet, and taking the center of the adhesive layer from the simulation results of the forming process as the reference, translate the nodes of the upper and lower plates and the fixture in the Y-axis direction so that the upper and lower plates and the fixture are in a position parallel to the outside of the transition layer; at the same time, the clamping end of the fixture moves relative to the reference to simulate the clamping situation in the experiment.

6. The rapid modeling method for refined numerical simulation model of glued joints according to claim 5, characterized in that, Define the thickness of the upper plate as T t The thickness of the lower plate is T. l The adhesive layer thickness is T g Then the upper plate moves a distance D t The lower plate moving distance D l The moving distance D of the upper clamp t1 The moving distance D of the upper clamping end t2 The moving distance D of the lower clamp l1 The moving distance D of the lower clamping end l2 Expressed as follows:

7. The rapid modeling method for refined numerical simulation models of adhesive riveting joints according to claim 1, characterized in that, The method for constructing the transition zone mesh is as follows: construct m transition layers to achieve the transition from a fine mesh region with mesh density A to a coarse mesh region with mesh density Z in the thickness direction of the plate. Each transition layer is composed of different transition schemes. The transition scheme refers to a certain combination of units that can achieve the transition of p units to q units, where m≥1, A>Z, and p>q.

8. The rapid modeling method for refined numerical simulation model of glued joints according to claim 7, characterized in that, Let transition scheme n will p n Each unit transitions to q n x units; the number of transition scheme 1 constituting the first transition layer is x. 11 The number of transition schemes 2 constituting the first transition layer is x. 12 ...the number of transition schemes that constitute the m-th transition layer is x. mn The first transition layer transitions A units to B units, the second transition layer transitions B units to C units, and so on, until the m-th transition layer transitions Y units to Z units, where A>B>C>…>Y>Z, and:

9. The rapid modeling method for refined numerical simulation model of glued joints according to claim 1, characterized in that, The method for mapping stress-strain field information is as follows: The stress and strain of the solid elements are obtained through linear interpolation of the spatial relationships between them; the spatial relationships between the solid elements are characterized by the number of intersection points, thus yielding the stress and strain of the solid elements denoted by P. N P N Let N be the original elements containing stress and strain information; S0 uniformly distributed points are taken in each element, and the stress in each element is represented by σ. N Let Q represent the target element to be mapped. When a target element is at any position in space, it may intersect N original elements in volume. Let S be the number of points of intersection. N Then the stress σ of the target element Q Q satisfy:

10. The rapid modeling method for refined numerical simulation model of glued joints according to claim 1, characterized in that, The thickness T of the Mth adhesive layer is calculated using a quadratic interpolation polynomial. gM Contact tangential failure stress σ sM Normal failure stress σ n’M The relationship is used to simulate the strength of the adhesive layer: Among them, a k b k σ is a coefficient. s0 This represents the calibrated contact tangential failure stress, σ. n’0 This indicates the calibrated contact normal failure stress.

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