Riveting failure simulation method and device based on equivalent entity unit

Abstract

The invention discloses a riveting failure simulation method and device based on equivalent entity units. The method comprises the following steps: acquiring base metal test data, establishing a material constitutive and fracture model, designing an experimental matrix of a connecting piece and obtaining an experimental result, establishing a connecting piece simulation model based on the experimental matrix, the material constitutive and fracture model, performing a microhardness test on a joint position to obtain a hardness change region, and determining a transition region of yield strength. The method comprises the following steps: establishing a mapping relation between hardness and yield strength of a transition region, analyzing a relation between the transition region and the yield strength of a base material to obtain a constitutive transition adjustment factor curve, performing optimization iteration on the constitutive transition adjustment factor curve in the transition region, and inputting the constitutive transition adjustment factor curve and a fracture transition adjustment factor curve into a keyword DEFINEHAZPROPERTIES of software LS-DYNA to obtain a fracture transition adjustment factor curve. A simulation curve of a material mechanical property test is obtained, a simulation result and an experiment are compared, the fracture precision is high, a material failure card of a connection area is obtained, and the deformation and failure behaviors of a riveting sample are accurately simulated.

Description

Technical Field

[0001] The present application relates to the technical field of riveting simulation, and in particular to a riveting failure simulation method and device based on equivalent solid units. Background Art

[0002] The automotive simulation industry refers to the industry that uses computer technology and simulation technology to simulate and experiment with the design, research and development, manufacturing, testing and other processes of automobiles. This industry is highly integrated with multiple fields such as computer technology, simulation technology, and automotive engineering, and is technology-intensive, knowledge-intensive, and capital-intensive.

[0003] Within the current technical framework, the failure analysis method for riveted structures in the automotive simulation industry is to carefully analyze the affected area formed during the rivet processing and its differences from the surrounding non-affected areas. The entire structure is divided into two parts, namely the area directly affected by the rivet and other areas that are not directly affected by the processing. Each part is given specific material properties based on different mechanical properties. Although this strategy aims to improve simulation accuracy by distinguishing material properties, its implementation process is full of challenges.

[0004] First, the complexity of the modeling stage increases significantly. Since the structure needs to be divided in detail and the parameters need to be set one by one, this not only consumes a lot of time and computing resources, but also requires the operator to have a deep knowledge of materials science and finite element analysis. In addition, the multiple settings of material properties are also prone to introduce human errors. Especially when dealing with complex geometries and multi-material assemblies, it is a difficult task to ensure that the properties of each area are correct. Secondly, the effect of this method is often unsatisfactory. On the one hand, the effect of riveting on materials is very complex. Residual stress and residual strain remain after processing, resulting in deviations in the prediction of macroscopic performance; on the other hand, the current methods used in riveting simulation in the automotive industry are simple scaling of the constitutive and fracture properties of raw materials, which cannot achieve the required simulation accuracy.

[0005] Therefore, while pursuing high fidelity, how to balance the complexity of modeling and the reliability of results has become a key issue that needs to be solved in this field. In practical operations, it still faces challenges such as complex modeling, low efficiency and limited accuracy. Summary of the invention

[0006] The purpose of this application is to overcome the existing technical defects and provide a riveting failure simulation method and device based on equivalent solid units, which can extremely accurately simulate the deformation and failure behavior of riveted specimens, solve the problems of complex modeling and low accuracy of simulation results in the existing technology, and the scheme can be applied to other similar connection methods such as spot welding.

[0007] The purpose of this application is achieved through the following technical solutions:

[0008] In a first aspect, the present application proposes a riveting failure simulation method based on an equivalent solid unit, the method comprising:

[0009] Obtain parent material test data, and establish material constitutive and fracture models based on the parent material test data;

[0010] Design the experimental matrix of the connector and obtain the experimental results. Establish the connector simulation model based on the experimental matrix, material constitutive model and fracture model. Perform microhardness test on the joint position to obtain the hardness change area.

[0011] Determine the transition region of yield strength according to the hardness change region, establish the mapping relationship between hardness and yield strength in the transition region, analyze the relationship between the transition region and the yield strength of the parent material, and obtain the constitutive transition adjustment factor curve;

[0012] The constitutive transition adjustment factor curve is optimized and iterated in the transition region to obtain the optimized constitutive transition adjustment factor curve. The optimized constitutive transition adjustment factor curve and the fracture transition adjustment factor curve are input into the keyword DEFINE_HAZ_PROPERTIES of the software LS-DYNA to obtain the simulation curve of the material mechanical properties test.

[0013] In a possible implementation, the parent material test data includes density, elastic modulus, yield strength, and stress-strain curve.

[0014] In one possible implementation, a fracture transition adjustment factor curve is added in the DEFINE_HAZ_PROPERTIES keyword.

[0015] In a possible implementation, the material mechanical property test includes a tensile shear specimen and a cross-pulling specimen.

[0016] In a second aspect, the present application also proposes a riveting failure simulation device based on an equivalent entity unit, the device comprising:

[0017] An acquisition module is used to acquire the parent material test data and establish the material constitutive and fracture models based on the parent material test data;

[0018] Construct the module, design the experimental matrix of the connector and obtain the experimental results, establish the connector simulation model based on the experimental matrix, material constitutive model and fracture model, and perform microhardness test on the joint position to obtain the hardness change area;

[0019] The first curve generating module is used to determine the transition region of the yield strength according to the hardness change region, convert the relationship between the hardness and the yield strength in the transition region, and obtain the constitutive transition adjustment factor curve;

[0020] The second curve generation module is used to iteratively optimize the constitutive transition adjustment factor curve in the transition area to obtain the optimized constitutive transition adjustment factor curve, and input the optimized constitutive transition adjustment factor curve and the fracture transition adjustment factor curve into the keyword DEFINE_HAZ_PROPERTIES of the software LS-DYNA to obtain the simulation curve of the material mechanical properties test.

[0021] In a possible implementation, the parent material test data includes density, elastic modulus, yield strength, and stress-strain curve.

[0022] In one possible implementation, a fracture transition adjustment factor curve is added in the DEFINE_HAZ_PROPERTIES keyword.

[0023] In a possible implementation, the material mechanical property test includes a tensile shear specimen and a cross-pulling specimen.

[0024] In a third aspect, the present application further proposes a computer device, comprising a processor and a memory, wherein the memory stores a computer program, and the computer program is loaded and executed by the processor to implement the riveting failure simulation method as described in any one of the first aspects.

[0025] In a fourth aspect, the present application further proposes a computer-readable storage medium, in which a computer program is stored. The computer program is loaded and executed by a processor to implement the riveting failure simulation method as described in any one of the first aspects.

[0026] The above main scheme of the present application and its further options can be freely combined to form multiple schemes, all of which are schemes that can be adopted and claimed for protection in the present application. After understanding the scheme of the present application, those skilled in the art can understand that there are multiple combinations based on the prior art and common knowledge, all of which are technical schemes to be protected by the present application, and they are not exhaustively listed here.

[0027] The present application discloses a riveting failure simulation method and device based on equivalent entity unit, obtains the test data of parent material, establishes the material constitutive and fracture model, designs the experimental matrix of the connector and obtains the experimental results, and establishes the connector simulation model based on the experimental matrix, material constitutive and fracture model. The microhardness test is carried out on the joint position to obtain the hardness change area, the transition area of ​​the yield strength is determined according to the hardness change area, and the mapping relationship between the hardness and yield strength of the transition area is established, the relationship between the transition area and the yield strength of the parent material is analyzed, and the constitutive transition adjustment factor curve is obtained. Finally, the constitutive transition adjustment factor curve is optimized and iterated in the transition area to obtain the optimized constitutive transition adjustment factor curve, and the optimized constitutive transition adjustment factor curve is input into the keyword DEFINE_HAZ_PROPERTIES of the software LS-DYNA together with the fracture transition adjustment factor curve to obtain the simulation curve of the material mechanical property test. It can simulate the deformation and failure behavior of the riveted specimen very accurately, solves the problem of complex modeling and low precision of simulation results in the prior art, and can be applied to other similar connection methods such as spot welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 A flow chart of a riveting failure simulation method based on equivalent solid units proposed in an embodiment of the present application is shown.

[0030] Figure 2 A schematic diagram of a tensile shear specimen proposed in an embodiment of the present application is shown.

[0031] Figure 3 A schematic diagram showing a cross-drawn specimen proposed in an embodiment of the present application

[0032] Figure 4 A relationship diagram of the hardness value versus distance proposed in the embodiment of the present application is shown.

[0033] Figure 5 A schematic diagram of a constitutive transition adjustment factor curve and a fracture transition adjustment factor curve proposed in an embodiment of the present application is shown.

[0034] Figure 6 Schematic diagram showing the equivalent rivet connection of the cross-drawn specimen proposed in the embodiment of the present application

[0035] Figure 7 A schematic diagram of a simulation curve of a tensile shear specimen proposed in an embodiment of the present application is shown.

[0036] Figure 8 A schematic diagram of a cross-drawing specimen simulation curve proposed in an embodiment of the present application is shown.

[0037] Fig. 9 A flow chart of another riveting failure simulation method based on equivalent solid units proposed in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0038] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0039] Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of this application.

[0040] Lightweight body and low-carbon design are important trends in the automotive industry. The lightweight of the entire vehicle pursues power, comfort, fuel economy and cruising range. The new aluminum alloy used has the advantages of low density, high specific strength, easy forming and corrosion resistance. The SPR riveting has the advantages of heterogeneous metal connection, safety, cleaning and automation, which are all important implementation methods for lightweight body and low-carbon design.

[0041] Therefore, while pursuing high fidelity, how to balance the complexity of modeling and the reliability of results has become a key issue that needs to be solved in this field. In practical operations, it still faces challenges such as complex modeling, low efficiency and limited accuracy.

[0042] In order to solve the above-mentioned technical problems, the embodiment of the present application proposes a riveting failure simulation method and device based on equivalent solid units, which can extremely accurately simulate the force-displacement curve of the failure of the riveted specimen, solving the problems of complex modeling and low accuracy of simulation results in the prior art, and the scheme can be applied to other similar connection methods such as spot welding, which will be described in detail below.

[0043] Please refer to Figure 1 , Figure 1 A schematic flow chart of a riveting failure simulation method based on equivalent entity units proposed in an embodiment of the present application is shown, and the method includes:

[0044] Step S100: Acquire parent material test data, and establish material constitutive and fracture models based on the parent material test data.

[0045] The parent material test data represents the experimental data of the material, including density, elastic modulus, yield strength, stress-strain curve, etc. It can make the geometric shape in the simulation become a "real" object.

[0046] For example, Table 1 shows the test data of XX steel parent material:

[0047] Table 1

[0048]

[0049]

[0050] Based on the parent material test data, the material constitutive and fracture models are established to predict material properties. The process is material testing, model calibration, model verification, and card output. Material testing uses multiple stress state tests. The calibration model calibrates the constitutive model and fracture model parameters. The verification model compares the simulation with the test results, including fracture location, fracture morphology, force displacement curve, etc. The card output generates material card information.

[0051] Step S200, designing an experimental matrix of the connector and obtaining experimental results, and establishing a connector simulation model based on the experimental matrix, material constitutive model and fracture model. Performing microhardness test on the joint position to obtain the hardness change area;

[0052] In engineering design and materials science research, the design of connectors must not only ensure that they meet structural strength and functional requirements, but also take into account the response of the material under complex loads, especially possible fracture behavior.

[0053] In order to systematically study the behavior of connectors under different working conditions, a series of experiments are designed. The experimental matrix usually includes different types of connector designs, different load conditions (such as tension, compression, torsion, fatigue, etc.) and different environmental factors (temperature, humidity, etc.). Each experiment is a point in the matrix to comprehensively examine the impact of various factors on connector performance, and key performance indicators such as stress-strain curves, fracture toughness data, and fatigue life of connectors can be obtained.

[0054] In some critical connection parts, hardness changes may occur due to stress concentration. By performing hardness testing on the joints of the connectors, areas of hardness changes caused by processing, heat treatment or load cycles can be identified. Hardness changes usually reflect changes in the material microstructure, such as grain refinement, changes in the distribution of second phases, or areas of plastic deformation. Analyzing these areas helps to understand the mechanism of fracture initiation and propagation, thereby providing guidance on how to improve the overall performance and reliability of the connector by changing the parameters of the material processing affected zone.

[0055] The material mechanical property test includes a tensile shear specimen and a cross-pulling specimen. In addition, the material mechanical property test can include a compression test, a bending test, an impact test, a fatigue test, a torsion test, etc., which is not limited in any way in the embodiments of the present application.

[0056] Since the stress state of automobile structural parts under service conditions is complex, a variety of tests with different stress states are generally used to test the strength of riveted joints. The three groups of riveted materials used use two types of joint specimens, shearing and cross-pulling, as examples for illustration. It is necessary to ensure that the rivets are riveted into the lower plate, the nail feet are open, and there are no riveting problems.

[0057] Figure 2 A schematic diagram of a tensile shear specimen proposed in an embodiment of the present application is shown. Figure 3 The schematic diagram of the cross-pulling specimen proposed in the embodiment of the present application is shown, in which the modeling method of solid unit connection is used to simulate the riveted joint, and the overall grid is controlled to be about 3mm. At the same time, the boundary conditions consistent with the test conditions are applied, the shear simulation extracts the 50mm virtual extensometer and the section force, and the cross-pulling simulation extracts the mobile end displacement and the node constraint force.

[0058] Step S300, determining the transition region of yield strength according to the hardness change region, establishing a mapping relationship between the hardness and yield strength of the transition region, analyzing the relationship between the transition region and the yield strength of the base material, and obtaining a constitutive transition adjustment factor curve.

[0059] After designing the material mechanical properties test based on the material constitutive and fracture model, the yield strengths of different areas are converted according to the relationship between hardness and yield strength. The constitutive transition adjustment factor curve is obtained by iterative optimization in different areas, and then the fracture transition adjustment factor curve is obtained by iterative optimization in the same area.

[0060] Through microhardness testing, the hardness tester probe is pressed into the material surface with a certain force, leaving an indentation, and the size of the indentation is measured to calculate the hardness. This process is repeated at different locations throughout the connector to draw a hardness change map. After that, the transition area needs to be determined by analyzing the hardness change map to identify the range of significant changes in hardness values, that is, the interval where the material changes from one state to another.

[0061] There is a certain correlation between hardness and yield strength, but this relationship is not linear. It is subject to the type of material, heat treatment state and other microstructural characteristics. In the transition region, due to the drastic change in hardness, a more complex model is needed to describe the nonlinear relationship between hardness and yield strength. Finally, the constitutive transition adjustment factor curve is obtained by fitting experimental data or calculating based on the theoretical model.

[0062] The range of the riveting affected area is confirmed by microhardness test, which is roughly 1.5 mm from the edge of the rivet. The hardness changes in the riveted area and other areas are measured. The yield strengths of different areas are calculated based on the relationship between hardness and yield strength, and the constitutive transition adjustment factor curve is obtained. The constitutive transition adjustment factor curve is a curve in which the yield strength proportionality coefficient changes with the distance from the rivet edge.

[0063] Figure 4 A relationship diagram of the hardness value proposed in the embodiment of the present application with the change of depth is shown, showing the change relationship of the hardness value (HV0.9) with the depth (mm). The horizontal axis in the chart represents the depth, and the vertical axis represents the hardness value. Each blue dot represents a specific measurement data point, and the line connecting these points represents the trend of the hardness value changing with depth. As can be seen from the figure, within the measured range, the hardness value remains roughly stable, with no obvious downward trend.

[0064] Figure 5 A schematic diagram of the constitutive transition adjustment factor curve and the fracture transition adjustment factor curve proposed in the embodiment of the present application is shown as a chart about the relationship between the yield strength proportionality coefficient and the distance from the edge of the rivet. According to the legend, it shows how two different types of adjustment factors (constitutive over-adjustment factor and fracture over-adjustment factor) change with the distance from the edge of the rivet. Each point on the curve represents the yield strength proportionality coefficient value measured at a specific distance.

[0065] Yield strength is usually the stress at which a material begins to deform permanently. In this chart, the yield strength ratio may refer to the ratio of the degree of deformation of a material under external force to the yield strength under standard conditions.

[0066] Step S400, optimizing and iterating the constitutive transition adjustment factor curve in the transition region to obtain an optimized constitutive transition adjustment factor curve, inputting the optimized constitutive transition adjustment factor curve and the fracture transition adjustment factor curve into the keyword DEFINE_HAZ_PROPERTIES of the software LS-DYNA to obtain a simulation curve of the material mechanical properties test.

[0067] In the cross-pulling specimen, the upper and lower plates are connected by equivalent rivets based on the solid unit method, and the size of the heat-affected zone is set according to the microhardness variation range to replace the riveting processing affected area. Figure 6 A schematic diagram of an equivalent rivet connection of a cross-drawn specimen proposed in an embodiment of the present application is shown, wherein the center position is a determined riveting influence zone.

[0068] The obtained constitutive transition adjustment factor curve and fracture transition adjustment factor curve are input into the keyword "DEFINE_HAZ_PROPERTIES" of the LS-DYNA software. This keyword can automatically identify the connection area and apply the yield strength of the parent material to the riveting process affected area after scaling.

[0069] Added fracture transition adjustment factor curve in DEFINE_HAZ_PROPERTIES keyword.

[0070] In addition, an additional line about the fracture transition adjustment factor is added to the keyword "DEFINE_HAZ_PROPERTIES". The process of adding this line needs to consider the results of the two models at the same time and further adjust the curve (this line is obtained through multiple attempts) to finally meet the requirements of both the fracture simulation displacement and the experimental fracture displacement under the two working conditions.

[0071] Figure 7 The following is a schematic diagram of the simulation curve of the shear test specimen proposed in the embodiment of the present application. The horizontal axis represents the displacement (in mm), and the vertical axis represents the force (in N). The curve shows the change of force with the change of displacement. By observing the chart, it can be seen that within a given displacement range, the force shows a trend of first increasing and then decreasing. The two lines correspond to the experimental data and the simulation correction data, respectively, comparing the difference between the actual measured value and the simulation prediction value. Similarly, Figure 8 A schematic diagram of a cross-drawing specimen simulation curve proposed in an embodiment of the present application is shown.

[0072] based on Figure 1 , please refer to Fig. 9 , Fig. 9 A schematic flow chart of another riveting failure simulation method based on equivalent entity units proposed in an embodiment of the present application is shown, and the flow chart is as follows:

[0073] Obtain parent material test data and establish material constitutive and fracture models;

[0074] Design the experimental matrix of the connector and obtain the experimental results, and establish the connector simulation model based on the experimental matrix, material constitutive model and fracture model. Perform microhardness test on the joint position to obtain the hardness change area; Perform microhardness test on the joint position to obtain the hardness change area;

[0075] The transition region of yield strength is determined according to the hardness change region, and the mapping relationship between the hardness and yield strength of the transition region is established. The relationship between the yield strength of the transition region and the parent material is analyzed to obtain the constitutive transition adjustment factor curve.

[0076] Optimize and iterate the constitutive transition adjustment factor curve in the transition region, and define the keyword DEFINE_HAZ_PROPERTIES of the software LS-DYNA;

[0077] Compare the nondestructive simulation results with the experimental results to determine whether the constitutive accuracy reaches 85%. If yes, proceed to the next step; otherwise, continue with the optimization iteration.

[0078] Optimize and iterate the fracture transition adjustment factor curve in the transition area, and add the curve to the keyword DEFINE_HAZ_PROPERTIES of the software LS-DYNA;

[0079] The simulation results are compared with the experimental results to determine whether the fracture accuracy reaches 85%. If so, the simulation curve of the material mechanical properties test is output, otherwise the optimization iteration is continued.

[0080] Worth noting:

[0081] First, when simulating riveted joints, it is necessary to focus on the differences in mechanical properties in the riveted area.

[0082] Second, it is recommended to use the HAZ card method to adjust the mechanical properties of the riveted area.

[0083] Third, in the simulation results obtained by using equivalent solid unit joint modeling, the deformation of the parent material is normal, but the fracture morphology of the joint does not match. This is an inevitable systematic error caused by the shell unit + solid unit connection method. Although there are differences in morphology, in general, this joint modeling method is easy to use and suitable for component and vehicle simulation. Therefore, it is still recommended to use this joint modeling method.

[0084] Therefore, the riveting failure simulation method proposed in the embodiment of the present application uses microhardness testing technology, combined with quantitative material yield strength changes during the riveting process as it varies with the distance from the riveting area. This series of changing hardness values ​​is plotted into a curve and input into the keyword "DEFINE_HAZ_PROPERTIES" of the LS-DYNA software, and the fracture transition adjustment factor curve is input at the same time. The material property changes in the riveted deformation zone are defined by a function with the distance from the riveting point as a variable. The continuous transition of the material hardening curve and the fracture strain in the riveted deformation zone can be achieved, and the force-displacement curve of the failure of the riveted specimen can be simulated very accurately.

[0085] A possible implementation of a riveting failure simulation device based on an equivalent entity unit is provided below, which is used to execute the various execution steps and corresponding technical effects of the riveting failure simulation method shown in the above embodiments and possible implementations.

[0086] The device includes:

[0087] An acquisition module is used to acquire the parent material test data and establish the material constitutive and fracture models based on the parent material test data;

[0088] The construction module is used to design the experimental matrix of the connector and obtain the experimental results. The simulation model of the connector is established based on the experimental matrix, material constitutive model and fracture model. The microhardness test of the joint position is carried out to obtain the hardness change area;

[0089] The first curve generation module determines the transition region of the yield strength according to the hardness change region, establishes a mapping relationship between the hardness and the yield strength of the transition region, analyzes the relationship between the transition region and the yield strength of the parent material, and obtains the constitutive transition adjustment factor curve.

[0090] The second curve generation module is used to iteratively optimize the constitutive transition adjustment factor curve in the transition area to obtain the optimized constitutive transition adjustment factor curve, define the keyword DEFINE_HAZ_PROPERTIES of the software LS-DYNA, add the optimized constitutive transition adjustment factor curve and the fracture transition adjustment factor curve to the keyword, and obtain the simulation curve of the material mechanical properties test.

[0091] In a possible implementation, the parent material test data includes density, elastic modulus, yield strength, and stress-strain curve.

[0092] In a possible implementation, the material mechanical property test includes a tensile shear specimen and a cross-pulling specimen.

[0093] The preferred embodiment of the present application provides a computer device, which can implement the steps in any embodiment of the riveting failure simulation method provided in the embodiment of the present application. Therefore, the beneficial effects of the riveting failure simulation method provided in the embodiment of the present application can be achieved. Please refer to the previous embodiments for details and will not be repeated here.

[0094] Those skilled in the art can understand that all or part of the steps in the various methods of the above embodiments can be completed by instructions, or by controlling related hardware through instructions, and the instructions can be stored in a computer-readable storage medium and loaded and executed by a processor. To this end, an embodiment of the present application provides a storage medium, which stores multiple instructions, and the instructions can be loaded by a processor to execute the steps of any embodiment of the riveting failure simulation method provided in the embodiment of the present application.

[0095] The storage medium may include: a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, etc.

[0096] Since the instructions stored in the storage medium can execute the steps in any riveting failure simulation method embodiment provided in the embodiments of the present application, the beneficial effects that can be achieved by any riveting failure simulation method provided in the embodiments of the present application can be achieved. Please refer to the previous embodiments for details and will not be repeated here.

[0097] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A riveting failure simulation method based on equivalent entity elements, characterized in that: The method comprises: Obtain parent material test data, and establish material constitutive and fracture models based on the parent material test data; Design the experimental matrix of the connector and obtain the experimental results. Establish the connector simulation model based on the experimental matrix, material constitutive model and fracture model. Perform microhardness test on the joint position to obtain the hardness change area. Determine the transition region of yield strength according to the hardness change region, establish the mapping relationship between hardness and yield strength in the transition region, analyze the relationship between the transition region and the yield strength of the parent material, and obtain the constitutive transition adjustment factor curve; The constitutive transition adjustment factor curve is optimized and iterated in the transition region, and the optimized constitutive transition adjustment factor curve and fracture transition adjustment factor curve are input into the keyword DEFINE_HAZ_PROPERTIES of the software LS-DYNA to obtain the simulation curve of the material mechanical properties test.

2. The riveting failure simulation method according to claim 1, characterized in that: The parent material test data includes density, elastic modulus, yield strength, and stress-strain curve.

3. The riveting failure simulation method according to claim 1, characterized in that: Added fracture transition adjustment factor curve in DEFINE_HAZ_PROPERTIES keyword.

4. The riveting failure simulation method according to claim 1, characterized in that: Material mechanical properties tests include tensile shear specimens and cross-pulling specimens.

5. A riveting failure simulation device based on equivalent entity unit, characterized in that: The device comprises: An acquisition module is used to acquire the parent material test data and establish the material constitutive and fracture models based on the parent material test data; Construct the module, design the experimental matrix of the connector and obtain the experimental results, establish the connector simulation model based on the experimental matrix, material constitutive model and fracture model, and perform microhardness test on the joint position to obtain the hardness change area; The first curve generation module is used to determine the transition area of ​​the yield strength according to the hardness change area, establish a mapping relationship between the hardness and the yield strength of the transition area, analyze the relationship between the transition area and the yield strength of the parent material, and obtain a constitutive transition adjustment factor curve; The second curve generation module is used to iteratively optimize the constitutive transition adjustment factor curve in the transition area to obtain the optimized constitutive transition adjustment factor curve, and input the optimized constitutive transition adjustment factor curve and the fracture transition adjustment factor curve into the keyword DEFINE_HAZ_PROPERTIES of the software LS-DYNA to obtain the simulation curve of the material mechanical properties test.

6. The riveting failure simulation device according to claim 5, characterized in that: The parent material test data includes density, elastic modulus, yield strength, plasticity curve and critical fracture curve.

7. The riveting failure simulation device according to claim 5, characterized in that: Added fracture transition adjustment factor curve in DEFINE_HAZ_PROPERTIES keyword.

8. The riveting failure simulation device according to claim 5, characterized in that: Material mechanical properties tests include tensile shear specimens and cross-pulling specimens.

9. A computer device, characterized in that: The computer device includes a processor and a memory, wherein a computer program is stored in the memory, and the computer program is loaded and executed by the processor to implement the riveting failure simulation method according to any one of claims 1 to 4.

10. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, which is loaded and executed by a processor to implement the riveting failure simulation method according to any one of claims 1 to 4.

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