Virtual contact surface element modeling method, device and data management system for bolt joint

Abstract

The present invention discloses a method, device and data management system for modeling virtual contact surface element of bolted joint, which relates to the technical field of joint modeling, including: establishing a virtual contact surface element model based on the contact characteristics of bolted joint; adjusting the connection parameters of bolts, obtaining geometric model parameters under different connection parameters, so as to establish a geometric model parameter library; constructing the stiffness matrix and mass matrix of the overall structure containing the bolted joint, obtaining the overall structural modal parameters, adjusting the assigned stiffness parameters, obtaining the mapping relationship between the stiffness parameters of the virtual contact surface element model and the overall structural modal parameters; obtaining the modal parameters of the dumbbell entity, determining the specific stiffness parameters of the virtual contact surface element model according to the mapping relationship, adjusting the preload torque, obtaining the specific stiffness parameters under different preload torques, so as to establish a stiffness model parameter library. The model established by the present application has a high degree of consistency with the actual situation of the bolted joint, and the stability of the recognition result is good.

Description

Technical Field

[0001] The present application relates to the technical field of joint modeling, and in particular to a method, device and data management system for modeling virtual contact surface elements of bolt joints. Background Art

[0002] High-end CNC machine tools are the working machines of modern manufacturing equipment. Realizing the autonomy of designing, manufacturing and producing high-performance and high-precision CNC machine tools is the only way to upgrade the manufacturing industry. Digital simulation technology can realize the dynamic and static analysis of the structure and the structural optimization design in the design stage, greatly shortening the design life cycle and improving the design quality of the product. The key lies in establishing an accurate digital model. Existing finite element software can well realize the digital modeling of individual components such as the bed and the column. However, for the connection part between the components (usually referred to as the joint surface), the general finite element software cannot provide an accurate mathematical model. The machine tool is usually composed of the bed, the column, the workbench, the drive mechanism and other components connected by related joints. Relevant research shows that more than 60% of its stiffness and about 90% of its damping come from the joint surface. It can be seen that establishing an accurate digital model of the joint surface is one of the key factors for accurately realizing the static and dynamic characteristics analysis and structural optimization design of the entire machine tool using digital simulation technology.

[0003] Bolts are the key joints in the connection of large parts such as machine tool beds and columns. There are many factors that affect the dynamic characteristics of bolt joints, and they are intertwined. It is very difficult to establish a general model that reflects the actual contact conditions. Moreover, the contact states of joints in different application scenarios are not the same during operation, and the model parameters will also change. The specific parameters of a single model cannot be used in engineering structures with variable structures. These are obstacles to the engineering application of joint models and are also key issues that must be solved to achieve accurate modeling of the entire machine.

[0004] Various models have been proposed for the modeling of joints. According to the contact form of the modeling, they can be divided into point contact-based models, surface contact-based models, and body contact-based models. Point contact-based models usually use various types of linear or nonlinear spring damping units to simulate joints. The modeling process is simple and convenient, but the traditional spring damping model usually ignores the coupling between normal and tangential degrees of freedom. Moreover, when the size of the connection structure itself or the mesh division situation changes, the specific number and specific distribution position of the spring damping unit need to be adjusted to obtain high-precision modeling. The modeling process has an important relationship with the structure itself and the mesh division situation, and the versatility of the model needs to be improved. The zero-thickness unit model and the eight-node hexahedron model reflect the coupling between the degrees of freedom in the plane. The modeling accuracy is high, but both models have more parameters and the modeling process is very complicated. It is not convenient for the optimization design and corresponding engineering applications that require repeated modification and iteration, and the versatility of the model is not enough.

[0005] When using the parameter identification method based on frequency response function, the test results near the resonance peak are usually excluded from the correction equation. The frequency response function far away from the resonance peak is less sensitive to the structural parameters. Due to the pathological characteristics of the sensitivity equation itself, the model parameter identification results are more sensitive to noise, and the stability of the identification results of this method is poor. When using the identification method based on modal parameters, due to the limitations of experimental test conditions, the measured modes are incomplete, and certain errors will be introduced in the modal condensation or expansion and parameter identification process. Moreover, when there are many correction parameters, the number of correction equations is insufficient and easily ill-conditioned, and the results of parameter identification may appear statically indeterminate.

[0006] According to the current research progress and results at home and abroad, there are still the following urgent problems to be solved in the dynamic modeling of bolted joints: (1) In the dynamic modeling of joints, the point contact model does not consider the size of the actual contact area, while the body contact model generally assumes that the contact stress of the contact surface uniformly covers the entire connection area, and neither fully considers the local characteristics of the contact surface of the connection; (2) In the identification of joint dynamic model parameters, the parameter identification methods based on dynamic testing basically use modal parameters or frequency response functions alone for parameter identification. There are problems such as too few equations involved in the correction, or the correction equations are highly correlated and the coefficient matrix is ​​seriously ill-conditioned. Summary of the invention

[0007] The present application provides a method, device and data management system for modeling virtual contact surface elements of bolt joints. The established model has a high degree of consistency with the actual situation of the bolt joints, and the stability of the recognition results is good.

[0008] In a first aspect, an embodiment of the present application provides a method for modeling a virtual contact surface element of a bolt joint, the method comprising:

[0009] Based on the contact characteristics of the bolt joint, a virtual contact surface element model is established;

[0010] Conducting contact analysis according to the connection parameters of the bolts to output radial contact stress, determining geometric model parameters of the virtual contact surface element model according to the contact stress, adjusting the connection parameters, obtaining geometric model parameters under different connection parameters, and establishing a geometric model parameter library of the virtual contact surface element model;

[0011] A dumbbell model without bolted joints is constructed, the stiffness matrix and mass matrix of the dumbbell model are determined, and the stiffness parameters of the virtual contact surface element model are assigned to construct the stiffness matrix and mass matrix of the overall structure with bolted joints. The modal parameters of the overall structure are obtained through modal analysis, and the stiffness parameters of the assigned virtual contact surface element model are adjusted to obtain the mapping relationship between the stiffness parameters of the virtual contact surface element model and the modal parameters of the overall structure.

[0012] The modal parameters of the dumbbell entity including the bolt joint are obtained, and the specific stiffness parameters of the virtual contact surface element model are determined according to the mapping relationship. The preload torque of the dumbbell entity is adjusted to obtain the specific stiffness parameters under different preload torques, so as to establish a stiffness model parameter library of the virtual contact surface element model.

[0013] In combination with the first aspect, in one implementation, establishing a virtual contact surface element model based on the contact characteristics of the bolt joint includes:

[0014] Based on the contact characteristics of the bolt joint, the contact influence area and the non-contact influence area are separated;

[0015] A virtual contact surface element model is established with the contact influence area as geometric parameters, wherein the geometric parameters include the influence radius of the contact influence area.

[0016] In combination with the first aspect, in one implementation, the connection parameters of the bolt include connection plate thickness, bolt diameter and bolt pre-tightening torque.

[0017] In combination with the first aspect, in one implementation, adjusting the connection parameter value to obtain the influence radius under different connection parameters to establish a geometric model parameter library of the virtual contact surface element model includes:

[0018] By changing the connection plate thickness, bolt diameter and bolt preload torque in the bolt joint contact analysis command stream established by APDL, the geometric model parameter values ​​under different contact conditions are obtained.

[0019] The interpolation method is used to construct the parameter library of the bolt joint geometric model.

[0020] In combination with the first aspect, in one implementation, the method further includes:

[0021] Taking the stiffness parameters of the virtual contact surface element model as input and the modal parameters of the dumbbell model as output, a neural network model between the stiffness parameters of the virtual contact surface element model and the modal parameters of the dumbbell model is constructed;

[0022] The deep learning method is used to obtain the parameters of the neural network model.

[0023] In combination with the first aspect, in one implementation, the method further includes:

[0024] According to the neural network model and the first six modal frequencies of the dumbbell entity, the specific stiffness parameters of the virtual contact surface element model are identified;

[0025] Substitute the identified specific stiffness parameters into the virtual contact surface element model to calculate the first six modal frequencies of the overall structure;

[0026] The error between the first six modal frequencies of the dumbbell entity and the first six modal frequencies of the overall structure is calculated. If the error meets the frequency constraint, the specific stiffness parameters identified are output; if the error does not meet the frequency constraint, the parameters of the neural network model are adjusted.

[0027] In combination with the first aspect, in one implementation, the stiffness parameters of the virtual contact surface element model include normal stiffness and coupling coefficient within the contact surface.

[0028] In combination with the first aspect, in one implementation, a dumbbell model with different normal stiffnesses and coupling coefficients is constructed;

[0029] The first six modal parameters of the dumbbell model under different normal stiffness and coupling coefficients are analyzed to obtain the mapping relationship between the stiffness parameters of the virtual contact surface element model and the modal parameters of the overall structure.

[0030] In a second aspect, an embodiment of the present application provides a virtual contact surface element modeling device for a bolt joint, the virtual contact surface element modeling device for a bolt joint includes:

[0031] A modeling module, which establishes a virtual contact surface element model based on the contact characteristics of the bolt joint;

[0032] A first identification module performs contact analysis according to the connection parameters of the bolt to output radial contact stress, determines geometric model parameters of the virtual contact surface element model according to the contact stress, adjusts the connection parameters, obtains geometric model parameters under different connection parameters, and establishes a geometric model parameter library of the virtual contact surface element model;

[0033] The second identification module is used to construct a dumbbell model without a bolted joint, determine the stiffness matrix and mass matrix of the dumbbell model, and assign stiffness parameters of the virtual contact surface element model to construct the stiffness matrix and mass matrix of the overall structure with the bolted joint, obtain the overall structure modal parameters through modal analysis, adjust the assigned stiffness parameters of the virtual contact surface element model, and obtain the mapping relationship between the stiffness parameters of the virtual contact surface element model and the overall structure modal parameters;

[0034] The second identification module is also used to obtain the modal parameters of the dumbbell entity containing the bolt joint, determine the specific stiffness parameters of the virtual contact surface element model according to the mapping relationship, adjust the preload torque of the dumbbell entity, and obtain the specific stiffness parameters under different preload torques to establish a stiffness model parameter library of the virtual contact surface element model.

[0035] In a third aspect, an embodiment of the present application provides a metadata management system for a virtual contact surface of a bolt joint, wherein the metadata management system for the virtual contact surface of a bolt joint includes a geometric model parameter library and a stiffness model parameter library generated by any one of the above-mentioned virtual contact surface meta-modeling methods for bolt joints.

[0036] The beneficial effects brought by the technical solution provided by the embodiment of the present application include at least:

[0037] The virtual contact surface element modeling method of the bolt joint in the present application establishes a virtual contact surface element model based on the contact characteristics of the bolt joint; performs contact analysis according to the connection parameters of the bolt to output radial contact stress, and determines the geometric model parameters of the virtual contact surface element model according to the contact stress, adjusts the connection parameters, and obtains the geometric model parameters under different connection parameters to establish a geometric model parameter library of the virtual contact surface element model; constructs a dumbbell model without a bolt joint, determines the stiffness matrix and mass matrix of the dumbbell model, and assigns the stiffness parameters of the virtual contact surface element model to construct the stiffness matrix and mass matrix of the overall structure containing the bolt joint, obtains the modal parameters of the overall structure through modal analysis, adjusts the stiffness parameters of the assigned virtual contact surface element model, and obtains the mapping relationship between the stiffness parameters of the virtual contact surface element model and the modal parameters of the overall structure; obtains the modal parameters of the dumbbell entity containing the bolt joint, determines the specific stiffness parameters of the virtual contact surface element model according to the mapping relationship, adjusts the preload torque of the dumbbell entity, and obtains the specific stiffness parameters under different preload torques to establish a stiffness model parameter library of the virtual contact surface element model.

[0038] That is, in terms of modeling, the present application fully considers the actual contact area of ​​the bolt joint and the contact stress characteristics within the contact surface, and establishes a virtual contact surface element model. The established model is highly consistent with the actual situation of the bolt joint.

[0039] In terms of parameter identification, contact analysis based on APDL language is used to identify the geometric parameters of the virtual contact surface element, and deep learning method is used to identify the stiffness parameters of the virtual contact surface element model.

[0040] In terms of application, MATLAB is used to establish a data management library for virtual contact surface elements. Users only need to input the bolt diameter, connection plate thickness and preload torque through the management interface to obtain the parameters of the virtual contact surface elements, which is very convenient to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of a flow chart of an embodiment of a method for modeling a virtual contact surface element of a bolt joint of the present application;

[0042] Figure 2 A schematic diagram of a virtual contact surface metamodel for this application;

[0043] Figure 3 Flow chart of geometric parameter identification for this application;

[0044] Figure 4 This is a flow chart for identifying stiffness parameters of contact surface elements for this application;

[0045] Figure 5 This is a schematic diagram for verifying the effectiveness of the contact surface element stiffness parameter identification method of this application;

[0046] Figure 6 A schematic diagram of the shape of the dumbbell solid specimen processed for this application;

[0047] Figure 7 This is a structural block diagram of an embodiment of a device for modeling a virtual contact surface element of a bolt joint of the present application;

[0048] Figure 8 This is a schematic diagram of the interface of the metadata management system for the virtual contact surface of the bolt joint in this application. DETAILED DESCRIPTION

[0049] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0050] It is worth noting that the purpose of this embodiment is to propose a simple and universal modeling method, and based on the characteristics of the bolt joint, propose a corresponding parameter identification method to achieve dynamic modeling and parameter identification of the bolt joint, and serve the dynamic characteristics analysis and structural optimization design of the whole machine tool.

[0051] In terms of dynamic modeling, according to the actual contact situation of the bolt joint, a virtual contact surface element model of the joint containing geometric parameters and stiffness parameters is established; the geometric parameters mainly describe the geometric shape and size of the actual contact area of ​​the joint, and the stiffness parameters mainly describe the mechanical properties in the contact area. The geometric parameters of the dynamic model are identified by combining experimental testing with finite element contact analysis. Since the established joint model fully considers the size of the actual influence area of ​​the bolt, it can better reflect the actual situation of the bolt connection and has high modeling accuracy.

[0052] In terms of parameter identification, based on the characteristic that the joint significantly affects the dynamic performance of the structure, a finite element model of the overall structure containing the bolt joint is established based on the constructed virtual contact surface element model. Then, the theoretical model parameters of the virtual contact surface element are used as the input data set, and the modal parameters under different theoretical model parameters are used as the output set to construct a neural network model between the virtual contact surface element model parameters and the natural frequency of the overall structure. The deep learning method is used to obtain the specific parameters of the neural network model, and then the natural frequency of the overall structure containing the joint tested in the experiment is used as the input to identify the stiffness parameters of the virtual contact surface element model.

[0053] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0054] In a first aspect, an embodiment of the present application provides a method for modeling a virtual contact surface element of a bolt joint.

[0055] In one embodiment, referring to Figure 1 , Figure 1 This is a flow chart of an embodiment of a method for modeling a virtual contact surface element of a bolt joint of the present application. Figure 1 As shown in FIG. 1 , the virtual contact surface element modeling method of the bolt joint includes:

[0056] S1. Based on the contact characteristics of the bolt joint, a virtual contact surface element model is established;

[0057] For details, see Figure 2 As shown, this embodiment separates the contact influence area and the non-contact influence area based on the contact characteristics of the bolt connection structure. The contact influence area actually works in the bolt connection. Therefore, a virtual contact surface element model is established with the actual contact influence area as the geometric parameter. In the contact influence area, for a single contact surface, the contact characteristics of the normal and tangential directions are significantly different. Therefore, within a single contact surface, a tangential and normal contact model is established; based on the relationship between the action force and the reaction force, combined with the mechanical characteristics of the two surfaces in contact with each other, a mechanical model of a pair of contact surface elements is established.

[0058] S2. performing contact analysis according to the connection parameters of the bolts to output radial contact stress, determining geometric model parameters of the virtual contact surface element model according to the contact stress, adjusting the connection parameters, obtaining geometric model parameters under different connection parameters, and establishing a geometric model parameter library of the virtual contact surface element model;

[0059] It is worth noting that by changing the parameters of the bolt connection, the APDL (ANSYS Parametric Design Language) command flow is used to analyze the influence of different parameters on the contact area and contact stress. According to the analysis results, the thickness of the connection plate and the bolt diameter have the most significant influence on the specific contact area; the bolt preload torque has the most significant influence on the contact stress within the contact surface. Therefore, the geometric model is established with the thickness of the connection plate and the bolt diameter as the main influencing factors.

[0060] According to the commonly used connection plate thickness and bolt diameter in mechanical products, the geometric model parameter values ​​under different contact conditions are obtained by changing the data of connection plate thickness and bolt diameter in the bolt joint contact analysis command stream established by APDL, and the interpolation method is used to construct the geometric model parameter library of bolt joints.

[0061] Specifically, see Figure 3 As shown in the figure, the first step is to use APDL language to establish a virtual contact surface element model of the bolt joint; then, MATLAB is used to call the relevant APDL program to perform contact analysis and output the radial contact stress; then, MATLAB is used to read the contact stress value analyzed by ANSYS; then, the minimum contact stress influence threshold is set, and the actual contact influence area is determined; then the above steps are repeated to analyze the influence area under different connection plate thicknesses and bolt diameters, thereby obtaining the geometric parameter library of the virtual contact surface element model.

[0062] S3, constructing a dumbbell model without a bolted joint, determining the stiffness matrix and mass matrix of the dumbbell model, and assigning stiffness parameters of the virtual contact surface element model to construct the stiffness matrix and mass matrix of the overall structure with the bolted joint, obtaining the overall structure modal parameters through modal analysis, adjusting the assigned stiffness parameters of the virtual contact surface element model, and obtaining the mapping relationship between the stiffness parameters of the virtual contact surface element model and the overall structure modal parameters;

[0063] S4. Obtain the modal parameters of the dumbbell entity including the bolt joint, determine the specific stiffness parameters of the virtual contact surface element model according to the mapping relationship, adjust the preload torque of the dumbbell entity, obtain the specific stiffness parameters under different preload torques, and establish a stiffness model parameter library of the virtual contact surface element model.

[0064] It is worth mentioning that, based on the significant influence of the joint on the dynamic characteristics of the overall structure, a dumbbell model including a bolt joint is designed to weaken the stiffness of the joint in the structure and highlight the dynamic characteristics of the joint in the overall structure.

[0065] In this embodiment, 2500 dumbbell models with different normal stiffness and coupling coefficients are constructed, and MATLAB is used to analyze the first six modal parameters of the dumbbell model under different contact stiffnesses to obtain the corresponding relationship between the stiffness parameters of different virtual contact surface element models and the modal parameters of the dumbbell model.

[0066] Taking the stiffness parameters of the virtual contact surface element model as input and the modal parameters of the dumbbell model as output, a neural network model between the stiffness parameters of the virtual contact surface element model and the modal parameters of the dumbbell model is constructed, and the specific parameters of the neural network model are obtained by using the deep learning method.

[0067] A dumbbell solid specimen with a bolted joint was manufactured, and the first six modal parameters were obtained by a modal experimental method. The relevant parameters were substituted into the above-mentioned neural network model to obtain the specific stiffness parameters of the virtual contact surface element model.

[0068] For specific implementation, see Figure 4 As shown in the figure, the first step is to use APDL language to write a dumbbell model without bolt joints; then, modal analysis is used to obtain the stiffness matrix and mass matrix of the dumbbell model without bolt joints, and MATLAB is used to extract the corresponding matrix; then, the stiffness value of the virtual contact surface element model is assigned through MATLAB, and the stiffness matrix and mass matrix of the overall structure of the component including the bolt joint are obtained; then, modal analysis is performed to obtain the first six modal vibration shapes and modal frequencies; then, the above steps are repeated, and different stiffness values ​​are assigned to the virtual contact surface element model, thereby constructing the virtual contact surface element stiffness of the dumbbell model. The mapping relationship between the parameters and the first six modal frequencies of the overall structure; then, the dumbbell physical specimen is processed and the modal test is carried out to obtain the first six modal frequencies; then, the stiffness parameters of the virtual contact surface element model are identified according to the neural network model; then, it is determined whether the error after identification meets the frequency constraint conditions, if not, the neural network model is adjusted, if it meets the frequency constraint conditions, the identification parameters are output; the modal experiment of the dumbbell physical specimen under different torques is repeated, the stiffness parameters under different preload torques are analyzed and obtained, and the stiffness model parameter library of the virtual contact surface element model is obtained.

[0069] The following cases are used to illustrate the effectiveness of the constructed virtual contact surface metamodel and to build a virtual contact surface metamodel parameter library that meets engineering applications.

[0070] Case 1: Using deep learning methods to illustrate the effectiveness of virtual contact surface element parameter identification methods

[0071] The theoretical model of the dumbbell solid specimen was constructed, and the normal stiffness k was set to the range of 1e7-5e8 with an interval of 1e7. In order to reduce the non-convergence of network training due to the difference in data magnitude, the coupling coefficient was multiplied by the normal stiffness and recorded as the coupling stiffness. The coupling stiffness was set in the range of 1e7-5e8 with an interval of 1e7. There were 2500 sets of data involved in the convolutional neural network, which were divided into training sets and test sets according to the ratio of 8:2, that is, 2000 sets of data were used as training sets and 500 sets of data were used as test sets. The 500 sets of test set data were substituted into the trained network, and the training set error was as follows: Figure 5 As shown. Figure 5 It can be seen that except for one set of data with an error of 1.55%, the errors of the remaining 499 sets of data are all less than 1%, and the average error of the 500 test data sets is 0.034%. This shows that the deep learning method can be used to identify the parameters of virtual contact surface elements.

[0072] Case 2: Using experimental structure to verify the effectiveness of virtual contact surface metamodel

[0073] In order to further verify the effectiveness of the constructed virtual contact surface element model, a dumbbell solid specimen with a roughness of 0.8 μm was machined and connected with two M12 bolts. Figure 6 As shown. A torque of 90Nm is applied to obtain the first 6 modal vibration modes and modal frequencies. The modal parameters are substituted into the constructed deep learning neural network to identify the stiffness k = 2.604e+08Nm and the coupling coefficient τ = 0.3281. The identified stiffness parameters are substituted into the virtual contact surface element model to calculate the first six modal frequencies. The first six modal frequencies and errors of the structure under the experimental values ​​and virtual contact surface element model parameters are shown in Table 1. It can be obtained from Table 1 that the errors of the first six modes of the virtual contact surface element model are 3.67%, 0.94%, -0.1%, -5.21%, -3.8%, and -1.91%, respectively. The maximum error is an absolute value of 5.21%, and the average error is an absolute value of 2.04%. The effectiveness of the virtual contact surface element model is verified.

[0074] Table 1 Virtual contact surface element model error

[0075]

[0076] Case 3: Using experimental structure to build a virtual contact surface metamodel parameter library

[0077] Since the actual contact conditions under different preloads and different processing states and roughnesses are different, in order to make the constructed virtual contact surface element model parameters meet engineering applications, the dumbbell solid specimens with a roughness of 0.8μm were respectively applied with torques of 30Nm, 45Nm, 60Nm, 75Nm, 90Nm, 105Nm, 120Nm, and 135Nm to obtain the first 6 modal vibration shapes and modal frequencies. The modal parameters were substituted into the constructed deep learning neural network to identify the contact stiffness k and coupling coefficient τ under different preloads. Then, the interpolation method was used to construct the virtual contact surface element model parameter library under different roughnesses, and the model parameter library management interface was developed based on MATLAB. Figure 8 for engineering applications.

[0078] In summary, the virtual contact surface element modeling method of the bolt joint in the present application establishes a virtual contact surface element model based on the contact characteristics of the bolt joint; performs contact analysis according to the connection parameters of the bolt to output radial contact stress, and determines the geometric model parameters of the virtual contact surface element model according to the contact stress, adjusts the connection parameters, and obtains the geometric model parameters under different connection parameters to establish a geometric model parameter library of the virtual contact surface element model; constructs a dumbbell model without a bolt joint, determines the stiffness matrix and mass matrix of the dumbbell model, and assigns the stiffness parameters of the virtual contact surface element model to construct the stiffness matrix and mass matrix of the overall structure containing the bolt joint, obtains the modal parameters of the overall structure through modal analysis, adjusts the stiffness parameters of the assigned virtual contact surface element model, and obtains the mapping relationship between the stiffness parameters of the virtual contact surface element model and the modal parameters of the overall structure; obtains the modal parameters of the dumbbell entity containing the bolt joint, determines the specific stiffness parameters of the virtual contact surface element model according to the mapping relationship, adjusts the preload torque of the dumbbell entity, and obtains the specific stiffness parameters under different preload torques to establish a stiffness model parameter library of the virtual contact surface element model.

[0079] That is, in terms of modeling, the present application fully considers the actual contact area of ​​the bolt joint and the contact stress characteristics within the contact surface, and establishes a virtual contact surface element model. The established model is highly consistent with the actual situation of the bolt joint.

[0080] In terms of parameter identification, contact analysis based on APDL language is used to identify the geometric parameters of the virtual contact surface element, and deep learning method is used to identify the stiffness parameters of the virtual contact surface element model.

[0081] In terms of application, MATLAB is used to establish a data management library for virtual contact surface elements. Users only need to input the bolt diameter, connection plate thickness and preload torque through the management interface to obtain the parameters of the virtual contact surface elements, which is very convenient to use.

[0082] In a second aspect, an embodiment of the present application also provides a device for modeling a virtual contact surface element of a bolt joint.

[0083] In one embodiment, referring to Figure 7 , Figure 7 This is a functional module diagram of an embodiment of a device for modeling a virtual contact surface element of a bolt joint of the present application. Figure 7 As shown, the virtual contact surface element modeling device of the bolt joint includes a modeling module, a first recognition module and a second recognition module.

[0084] Among them, a modeling module establishes a virtual contact surface element model based on the contact characteristics of the bolt joint;

[0085] A first identification module performs contact analysis according to the connection parameters of the bolt to output radial contact stress, determines geometric model parameters of the virtual contact surface element model according to the contact stress, adjusts the connection parameters, obtains geometric model parameters under different connection parameters, and establishes a geometric model parameter library of the virtual contact surface element model;

[0086] The second identification module is used to construct a dumbbell model without a bolted joint, determine the stiffness matrix and mass matrix of the dumbbell model, and assign stiffness parameters of the virtual contact surface element model to construct the stiffness matrix and mass matrix of the overall structure with the bolted joint, obtain the overall structure modal parameters through modal analysis, adjust the assigned stiffness parameters of the virtual contact surface element model, and obtain the mapping relationship between the stiffness parameters of the virtual contact surface element model and the overall structure modal parameters;

[0087] The second identification module is also used to obtain the modal parameters of the dumbbell entity containing the bolt joint, determine the specific stiffness parameters of the virtual contact surface element model according to the mapping relationship, adjust the preload torque of the dumbbell entity, and obtain the specific stiffness parameters under different preload torques to establish a stiffness model parameter library of the virtual contact surface element model.

[0088] Furthermore, in one embodiment, the modeling module establishes a virtual contact surface element model based on the contact characteristics of the bolt joint, including:

[0089] Based on the contact characteristics of the bolt joint, the contact influence area and the non-contact influence area are separated;

[0090] A virtual contact surface element model is established with the contact influence area as geometric parameters, wherein the geometric parameters include the influence radius of the contact influence area.

[0091] Furthermore, in one embodiment, the connection parameters of the bolts include connection plate thickness, bolt diameter and bolt pre-tightening torque.

[0092] Furthermore, in one embodiment, the first identification module adjusts the connection parameter value to obtain the influence radius under different connection parameters to establish a geometric model parameter library of the virtual contact surface element model, including:

[0093] By changing the connection plate thickness, bolt diameter and bolt preload torque in the bolt joint contact analysis command stream established by APDL, the geometric model parameter values ​​under different contact conditions are obtained.

[0094] The interpolation method is used to construct the parameter library of the bolt joint geometric model.

[0095] Furthermore, in one embodiment, the second identification module is further used for:

[0096] Taking the stiffness parameters of the virtual contact surface element model as input and the modal parameters of the dumbbell model as output, a neural network model between the stiffness parameters of the virtual contact surface element model and the modal parameters of the dumbbell model is constructed;

[0097] The deep learning method is used to obtain the parameters of the neural network model.

[0098] Furthermore, in one embodiment, the second identification module is further used for:

[0099] According to the neural network model and the first six modal frequencies of the dumbbell entity, the specific stiffness parameters of the virtual contact surface element model are identified;

[0100] Substitute the identified specific stiffness parameters into the virtual contact surface element model to calculate the first six modal frequencies of the overall structure;

[0101] The error between the first six modal frequencies of the dumbbell entity and the first six modal frequencies of the overall structure is calculated. If the error meets the frequency constraint, the specific stiffness parameters identified are output; if the error does not meet the frequency constraint, the parameters of the neural network model are adjusted.

[0102] Furthermore, in one embodiment, the stiffness parameters of the virtual contact surface element model include normal stiffness and coupling coefficient within the contact surface.

[0103] Furthermore, in one embodiment, the second identification module is further used for:

[0104] Construct dumbbell models with different normal stiffness and coupling coefficients;

[0105] The first six modal parameters of the dumbbell model under different normal stiffness and coupling coefficients are analyzed to obtain the mapping relationship between the stiffness parameters of the virtual contact surface element model and the modal parameters of the overall structure.

[0106] Among them, the functional implementation of each module in the above-mentioned virtual contact surface element modeling device of the bolt joint corresponds to the various steps in the above-mentioned embodiment of the virtual contact surface element modeling method of the bolt joint, and its functions and implementation processes will not be repeated here one by one.

[0107] In a third aspect, an embodiment of the present application provides a metadata management system for a virtual contact surface of a bolt joint, which includes a geometric model parameter library and a stiffness model parameter library generated by a virtual contact surface element modeling method for a bolt joint as described in any one of the above-mentioned methods.

[0108] It can be understood that, based on the established geometric model parameter library and stiffness model parameter library, a metadata management system for the virtual contact surface of the bolt joint can be developed, see Figure 8 As shown in the figure, the user only needs to input the bolt diameter, connection plate thickness and preload torque to obtain the parameters of the virtual contact surface element.

[0109] The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. The terms "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequence, nor do they limit "first", "second" and "third" to different types.

[0110] In the description of the embodiments of the present application, "exemplary", "for example" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary", "for example" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary", "for example" or "for example" is intended to present related concepts in a specific way.

[0111] In the description of the embodiments of the present application, unless otherwise specified, “ / ” means or, for example, A / B can mean A or B; the “and / or” in the text is merely a description of the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, “multiple” refers to two or more than two.

[0112] In some processes described in the embodiments of the present application, multiple operations or steps that appear in a specific order are included, but it should be understood that these operations or steps may not be executed in the order in which they appear in the embodiments of the present application or in parallel, and the sequence number of the operation is only used to distinguish the different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed in sequence or in parallel, and these operations or steps may be combined.

[0113] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for modeling virtual contact surface elements of bolt joints, characterized in that: The virtual contact surface element modeling method of the bolt joint part includes: Based on the contact characteristics of the bolt joint, a virtual contact surface element model is established; Conducting contact analysis according to the connection parameters of the bolts to output radial contact stress, determining geometric model parameters of the virtual contact surface element model according to the contact stress, adjusting the connection parameters, obtaining geometric model parameters under different connection parameters, and establishing a geometric model parameter library of the virtual contact surface element model; A dumbbell model without bolted joints is constructed, the stiffness matrix and mass matrix of the dumbbell model are determined, and the stiffness parameters of the virtual contact surface element model are assigned to construct the stiffness matrix and mass matrix of the overall structure with bolted joints. The modal parameters of the overall structure are obtained through modal analysis, and the stiffness parameters of the assigned virtual contact surface element model are adjusted to obtain the mapping relationship between the stiffness parameters of the virtual contact surface element model and the modal parameters of the overall structure. The modal parameters of the dumbbell entity including the bolt joint are obtained, and the specific stiffness parameters of the virtual contact surface element model are determined according to the mapping relationship. The preload torque of the dumbbell entity is adjusted to obtain the specific stiffness parameters under different preload torques, so as to establish a stiffness model parameter library of the virtual contact surface element model.

2. The method for modeling a virtual contact surface element of a bolt joint according to claim 1, characterized in that: The virtual contact surface element model is established based on the contact characteristics of the bolt joint, including: Based on the contact characteristics of the bolt joint, the contact influence area and the non-contact influence area are separated; A virtual contact surface element model is established with the contact influence area as geometric parameters, wherein the geometric parameters include the influence radius of the contact influence area.

3. The method for modeling a virtual contact surface element of a bolt joint according to claim 1, characterized in that: The connection parameters of the bolts include connection plate thickness, bolt diameter and bolt pre-tightening torque.

4. The method for modeling a virtual contact surface element of a bolt joint according to claim 3, characterized in that: The adjusting of the connection parameter value to obtain the influence radius under different connection parameters to establish a geometric model parameter library of the virtual contact surface element model includes: By changing the connection plate thickness, bolt diameter and bolt preload torque in the bolt joint contact analysis command stream established by APDL, the geometric model parameter values ​​under different contact conditions are obtained. The interpolation method is used to construct the parameter library of the bolt joint geometric model.

5. The method for modeling virtual contact surface element of bolt joint according to claim 1, characterized in that: Also includes: Taking the stiffness parameters of the virtual contact surface element model as input and the modal parameters of the dumbbell model as output, a neural network model between the stiffness parameters of the virtual contact surface element model and the modal parameters of the dumbbell model is constructed; The deep learning method is used to obtain the parameters of the neural network model.

6. The method for modeling virtual contact surface element of bolt joint according to claim 5, characterized in that: Also includes: According to the neural network model and the first six modal frequencies of the dumbbell entity, the specific stiffness parameters of the virtual contact surface element model are identified; Substitute the identified specific stiffness parameters into the virtual contact surface element model to calculate the first six modal frequencies of the overall structure; The error between the first six modal frequencies of the dumbbell entity and the first six modal frequencies of the overall structure is calculated. If the error meets the frequency constraint, the specific stiffness parameters identified are output; if the error does not meet the frequency constraint, the parameters of the neural network model are adjusted.

7. The method for modeling virtual contact surface elements of bolt joints according to claim 1, characterized in that: The stiffness parameters of the virtual contact surface element model include normal stiffness and coupling coefficient within the contact surface.

8. The method for modeling virtual contact surface elements of bolted joints according to claim 7, characterized in that: Construct dumbbell models with different normal stiffness and coupling coefficients; The first six modal parameters of the dumbbell model under different normal stiffness and coupling coefficients are analyzed to obtain the mapping relationship between the stiffness parameters of the virtual contact surface element model and the modal parameters of the overall structure.

9. A bolt joint virtual contact surface element modeling device, characterized in that: The virtual contact surface element modeling device of the bolt joint part comprises: A modeling module, which establishes a virtual contact surface element model based on the contact characteristics of the bolt joint; A first identification module performs contact analysis according to the connection parameters of the bolt to output radial contact stress, determines geometric model parameters of the virtual contact surface element model according to the contact stress, adjusts the connection parameters, obtains geometric model parameters under different connection parameters, and establishes a geometric model parameter library of the virtual contact surface element model; The second identification module is used to construct a dumbbell model without a bolted joint, determine the stiffness matrix and mass matrix of the dumbbell model, and assign stiffness parameters of the virtual contact surface element model to construct the stiffness matrix and mass matrix of the overall structure with the bolted joint, obtain the overall structure modal parameters through modal analysis, adjust the assigned stiffness parameters of the virtual contact surface element model, and obtain the mapping relationship between the stiffness parameters of the virtual contact surface element model and the overall structure modal parameters; The second identification module is also used to obtain the modal parameters of the dumbbell entity containing the bolt joint, determine the specific stiffness parameters of the virtual contact surface element model according to the mapping relationship, adjust the preload torque of the dumbbell entity, and obtain the specific stiffness parameters under different preload torques to establish a stiffness model parameter library of the virtual contact surface element model.

10. A metadata management system for virtual contact surfaces of bolted joints, characterized in that: The bolt joint virtual contact surface metadata management system includes a geometric model parameter library and a stiffness model parameter library generated by the bolt joint virtual contact surface metadata modeling method according to any one of claims 1 to 8.

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