Modeling method of electrothermal wear of electrical contacts under current-carrying fretting conditions

Abstract

The present invention discloses a method for modeling the electrothermal wear of electrical contact under current-carrying micro-motion conditions, which belongs to the field of microelectronics and includes the following steps: S1: selecting electrical contact materials, determining material parameters and load conditions; S2: conducting current-carrying electrical contact wear experiments to obtain the evolution law of wear coefficient and contact resistance; S3: establishing a micro-motion wear finite element model; S4: establishing an ABAQUS‑PYTHON‑MATLAB joint simulation method to simulate physical fields and wear evolution; S5: comparing with experimental results, verifying the model and optimizing parameters. The present invention can accurately simulate the wear morphology and evolution of wear volume in the contact area during current-carrying wear, as well as the distribution of various physical fields such as electric field, temperature field, stress strain field, etc., and can be used to evaluate the electrical contact state and behavior of electrical equipment to ensure the operational reliability of electrical equipment.

Description

Technical Field

[0001] The invention relates to the field of microelectronics, and in particular to an electrothermal wear modeling method of electric contact under current-carrying micro-motion conditions. Background Art

[0002] Electrical contact is the state of transmitting current or signals between conductors through contact, and is widely used in electronic and electrical equipment. Electrical contact usually involves a variety of physical phenomena, including electrical, thermal, and mechanical aspects. The electrical contact points are subjected to external mechanical vibrations and impact loads, which will cause severe micro-motion wear on the contact surface. Micro-motion will cause surface damage and change the morphology of the contact area, reducing the stability of the electrical contact, and is one of the main factors causing electrical contact failure. The introduction of micro-motion wear will make the coupling relationship between electrical, thermal, and mechanical behaviors in electrical contact more complicated.

[0003] At present, the research on electrical contact behavior under micro-motion conditions mainly adopts two methods: experimental and numerical. The experimental method is to conduct electrical contact micro-motion wear experiments to analyze the effects of different micro-motion wear conditions on wear mechanism, contact resistance and electrical contact life. However, it is difficult to clearly describe the coupling relationship between mechanical, electrical and thermal behaviors through experimental methods. In addition, the experimental method cannot accurately obtain the distribution of contact pressure, potential and temperature inside the wear area, and it is difficult to describe the evolution of wear profile and morphology. The numerical method is to establish an electrical contact micro-motion wear model, which can simulate the multi-physical field coupling behavior of electrical contact under micro-motion wear conditions, and has unique advantages in analyzing and reproducing electrical contact behavior and studying its influencing factors. However, most current studies only focus on micro-motion wear and electrical contact behavior separately, and fail to combine the two, or the established numerical methods do not consider experimental data, resulting in poor accuracy.

[0004] Therefore, those skilled in the art provide a method for modeling the electrothermal wear of electrical contacts under current-carrying micro-motion conditions to solve the problems raised in the above-mentioned background technology. Summary of the invention

[0005] The purpose of the present invention is to provide an electrothermal wear modeling method for electrical contact under current-carrying micro-motion conditions, which can accurately simulate the wear morphology of the contact area, the evolution of the wear volume, and the distribution of various physical fields such as electric field, temperature field, stress and strain field during the current-carrying wear process, so as to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The method for modeling the electrothermal wear of electrical contacts under current-carrying micro-motion conditions includes the following steps:

[0008] S1: Select electrical contact material, determine material parameters and load conditions;

[0009] S2: Conduct current-carrying electrical contact wear experiments to obtain the evolution law of wear coefficient and contact resistance;

[0010] S3: Establish fretting wear finite element model;

[0011] S4: Establish ABAQUS-PYTHON-MATLAB joint simulation method to simulate physical fields and wear evolution;

[0012] S5: Compare with experimental results to verify the model and optimize parameters.

[0013] As a further solution of the present invention: in step S1, the material parameters of the electrical contact material include density ρ, elastic modulus E, Poisson's ratio ν, thermal expansion coefficient β, specific heat capacity C p , conductivity γ e and thermal conductivity k t , the load conditions include normal force P, micro-motion amplitude δ s and current load I.

[0014] As a further solution of the present invention: in step S2, the specific process of obtaining the evolution law of the wear coefficient and the contact resistance is as follows:

[0015] S201: Conduct current-carrying electrical contact fretting wear experiments and use the four-wire method to measure the evolution of contact resistance with the number of fretting cycles;

[0016] S202: collecting the critical number of micromotion cycles, that is, the number of micromotion cycles corresponding to a sudden increase in contact resistance;

[0017] S203: characterize the probability distribution of the critical fretting cycle number using Weibull distribution;

[0018] S204: Use the parabolic oxidation model to fit the evolution law of contact resistance;

[0019] S205: using a surface topography instrument to measure the wear volume variation data with micro-motion cycles;

[0020] S206: Calculating the wear coefficient at different cycle times according to the dissipated energy model;

[0021] S207: fitting the evolution of the wear coefficient based on a power function model;

[0022] S208: Establish an evolution model of the contact resistance and the wear coefficient along with the micro-motion wear cycle, so as to obtain the evolution law of the wear coefficient and the contact resistance.

[0023] As a further solution of the present invention: in step S3, the fretting wear finite element model is a three-dimensional ball-plate contact finite element model established by ABAQUS software, which is used to analyze the fretting wear under electrical contact conditions.

[0024] As a further solution of the present invention: in the step S4, the initial parameters and model are imported into the established ABAQUS-PYTHON-MATLAB joint simulation method to simulate the evolution of electric field, temperature field, stress-strain field and wear morphology. In this method, ABAQUS is the main computing platform, and PYTHON and MATLAB are used for parameter post-processing and updating of calculation files submitted by ABAQUS.

[0025] As a further solution of the present invention: in the step S5, the verification model and optimization parameters are specifically: the wear profile and contact area temperature obtained by the simulation method are compared with the experimental results to verify the effectiveness of the method; the comparison content includes but is not limited to the wear profile, wear volume and contact area temperature rise; and the key parameters in the numerical simulation method are optimized according to the comparison results.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention establishes an electric-thermal-mechanical-wear modeling method for electrical contact under current-carrying micromotion conditions to evaluate the electrical contact behavior under micromotion conditions. Micromotion wear tests are carried out on the micromotion wear behavior under electrical contact conditions. An evolution model of contact resistance and wear coefficient is established based on the experimental results; a micromotion wear finite element model is established; an ABAQUS-PYTHON-MATLAB joint simulation method is introduced to perform cyclic iterative calculations; and finally the electric-thermal-mechanical-wear behavior of the contact area under current-carrying micromotion conditions is simulated. This simulation method can accurately simulate the wear morphology and evolution of the wear volume of the contact area during the current-carrying wear process, as well as the distribution of various physical fields such as electric field, temperature field, stress strain field, etc., and can be used to evaluate the electrical contact state and behavior of electrical equipment to ensure the operational reliability of the electrical equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flow chart of the electric-thermal-mechanical-wear modeling method of the electric contact under current-carrying micro-motion conditions of the present invention.

[0029] Figure 2 It is a schematic diagram of the current-carrying micro-motion wear test sample of the present invention.

[0030] Figure 3 It is a schematic diagram of the current-carrying micro-motion wear test instrument of the present invention.

[0031] Figure 4 It is a contact resistance experimental data diagram of the present invention.

[0032] Figure 5 It is the distribution histogram and probability density diagram of the critical cycle number of contact resistance of the present invention.

[0033] Figure 6 It is a schematic diagram of a simulation model of the present invention.

[0034] Figure 7 It is a schematic diagram of the grid division and boundary conditions of the present invention.

[0035] Figure 8 It is a schematic diagram of the load history of the finite element model of the present invention.

[0036] Fig. 9 It is a flow chart of the ABAQUS-PYTHON-MATLAB joint simulation algorithm of the present invention.

[0037] Fig.10 It is a schematic diagram comparing the wear volume simulation results of the present invention with the experimental data.

[0038] Fig.11 It is a schematic diagram comparing the wear morphology simulation results of the present invention with the experimental data.

[0039] Fig.12 It is a schematic diagram comparing the temperature rise simulation results of the present invention with the experimental data. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] As mentioned in the background technology of this application, the inventors have discovered through research that existing studies on electrical contact behavior under micro-motion conditions mainly use two methods: experimental and numerical. However, most current studies only focus on micro-motion wear and electrical contact behavior respectively, and fail to combine the two, or the established numerical methods do not take into account experimental data, resulting in poor accuracy and certain defects.

[0042] In order to solve the above-mentioned defects, the present application discloses an electrothermal wear modeling method for electrical contact under current-carrying micro-motion conditions, which can accurately simulate the wear morphology and evolution of wear volume in the contact area during current-carrying wear, as well as the distribution of various physical fields such as electric field, temperature field, stress and strain field, etc.

[0043] The following will describe in detail how the solution of the present application solves the above technical problems in conjunction with the accompanying drawings.

[0044] See also Figure 1 In the embodiment of the present invention, the electro-thermal-mechanical wear modeling method of electric contact under current-carrying micro-motion conditions includes the following steps: S1: selecting an electric contact material, determining material parameters and load conditions; S2: conducting a current-carrying electric contact wear experiment to obtain the evolution law of wear coefficient and contact resistance; S3: establishing a micro-motion wear finite element model; S4: establishing an ABAQUS-PYTHON-MATLAB joint simulation method to simulate the physical field and wear evolution; S5: comparing with the experimental results, verifying the model and optimizing parameters. The present invention selects a certain electric contact material to establish an electro-thermal-mechanical-wear modeling method of electric contact under current-carrying micro-motion conditions to evaluate the electric contact behavior under micro-motion conditions. Micro-motion wear tests are carried out on the micro-motion wear behavior under electric contact conditions. According to the experimental results, an evolution model of contact resistance and wear coefficient is established; a micro-motion wear finite element model is established; an ABAQUS-PYTHON-MATLAB joint simulation method is introduced to perform cyclic iterative calculations; and finally the electro-thermal-mechanical-wear behavior of the contact area under current-carrying micro-motion conditions is simulated. This simulation method can accurately simulate the wear morphology of the contact area and the evolution of the wear volume during current-carrying wear, as well as the distribution of various physical fields such as electric field, temperature field, stress and strain field, and can be used to evaluate the electrical contact state and behavior of electrical equipment to ensure the operational reliability of electrical equipment.

[0045] In this embodiment, in step S1, the material parameters of the electrical contact material include density ρ, elastic modulus E, Poisson's ratio ν, thermal expansion coefficient β, specific heat capacity C p , conductivity γ e and thermal conductivity k t , the load conditions include normal force P, micro-motion amplitude δ s and current load I.

[0046] In this embodiment, in step S2, the specific process of obtaining the evolution law of the wear coefficient and the contact resistance is as follows: S201: carry out a current-carrying electrical contact micro-motion wear experiment, and use the four-wire method to measure the evolution data of the contact resistance with the number of micro-motion cycles; S202: collect the critical micro-motion cycle number, that is, the number of micro-motion cycles corresponding to the sudden increase in contact resistance; S203: use Weibull distribution to characterize the probability distribution of the critical micro-motion cycle number; S204: use the parabolic oxidation model to fit and model the evolution law of the contact resistance; S205: use a surface topography instrument to measure the change data of the wear volume with micro-motion cycles; S206: calculate the wear coefficient under different cycle numbers according to the dissipated energy model; S207: fit the evolution of the wear coefficient based on the power function model; S208: establish an evolution model of the contact resistance and the wear coefficient with the micro-motion wear cycle, so as to obtain the evolution law of the wear coefficient and the contact resistance.

[0047] In this embodiment, in step S3, the fretting wear finite element model is a three-dimensional ball-plate contact finite element model established using ABAQUS software, which is used to analyze the fretting wear under electrical contact conditions. The added load conditions include the normal force P, the current I, the fretting amplitude δ s etc. boundary conditions.

[0048] In this embodiment, in step S4, the initial parameters and model are imported into the established ABAQUS-PYTHON-MATLAB joint simulation method to simulate the evolution of electric field, temperature field, stress-strain field and wear morphology. In this method, ABAQUS is the main computing platform, and PYTHON and MATLAB are used for parameter post-processing and updating of calculation files submitted by ABAQUS.

[0049] In this embodiment, in step S5, the verification model and optimization parameters are specifically as follows: the wear profile and contact area temperature obtained by the simulation method are compared with the experimental results to verify the effectiveness of the method; the comparison content includes but is not limited to the wear profile, wear volume and contact area temperature rise; and the key parameters in the numerical simulation method are optimized according to the comparison results.

[0050] For details, please refer to Figures 1 to 12 The present invention provides a specific embodiment based on the electrical-thermal-mechanical-wear modeling of the electrical contact of the common brass material CuZn40 alloy under current-carrying micro-motion conditions:

[0051] like Figure 2 As shown, the CuZn40 alloy test sample is a flat cylinder with a diameter of 24.3mm and a height of 7.8mm. The diameter of the upper spherical sample is 6mm. The material parameters are shown in Table 1. For CuZn40 alloy electrical contact materials, a commonly used research load condition is shown in Table 2.

[0052] Table 1 CuZn40 alloy material parameters

[0053]

[0054]

[0055] Table 2 Load conditions for the study of fretting wear of CuZn40 alloy in electrical contact

[0056]

[0057] like Figure 3As shown in the figure, the fretting wear test under electrical contact conditions was carried out. The experimental device mainly consists of two subsystems: the fretting wear system and the electrical contact system. The fretting wear tester RTECMFT-5000 was used to generate reciprocating motion in the fretting wear system. The electrical contact system includes contact resistance measurement and temperature measurement. The evolution of contact resistance during fretting wear was collected by the four-wire method. A constant current was generated by a constant current source, and a digital nanovoltmeter (Keithley 2460) was used to measure the voltage between the spherical sample and the cylindrical sample. The contact resistance was calculated based on Ohm's law. A mid-wave infrared thermal imaging camera (FLIR X6520sc) was used to collect the temperature at the edge of the contact area. After the fretting wear test, the wear volume, wear area and wear surface profile of the wear scar were measured using a white light interferometer profilometer (Zegage Plus, Zygo, USA).

[0058] like Figure 4 As shown in the figure, the evolution law of five groups of contact resistance collected based on the four-wire method in the current-carrying micro-wear test. When establishing the contact resistance evolution model, the change of contact resistance is divided into three stages. In the first stage, the contact resistance is stable at a low value without significant change. The contact resistance can be expressed as a constant cons1, whose value is the average value of the experimental results. N A Indicates the number of fretting cycles at the end of this stage. In the second stage, fretting wear begins and the debris begins to oxidize, resulting in a slight increase in contact resistance. Contact resistance R c The changes in this stage can be described by an exponential function:

[0059] R c =me n·N ,(1)

[0060] Where N is the number of fretting cycles; m and n represent the fitting parameters obtained based on the coordinates of points A and B in the figure. In the third stage, the value of the contact resistance increases sharply due to the oxidation and accumulation of a large amount of wear debris. cri Indicates the number of micro-motion cycles at the beginning of this stage, such as Figure 4 As shown in point B.

[0061] N cri and N A The relationship between them is as follows:

[0062] N A =a·N cri , (2)

[0063] where a is a constant parameter obtained from the experiment. After point B, the contact resistance changes sharply. The position of point B is variable for different experiments. The value of the corresponding contact resistance at point B (cons2) is relatively less scattered and can be determined by the average value of the experimental results. Parabolic oxidation kinetics is usually used to describe the oxidation process of metals with thick coherent oxides (such as copper and iron), that is, Where w and t represent the oxide layer thickness and time; k p is the parabolic oxidation rate. Therefore, a similar relationship between contact resistance and fretting cycles is proposed to express the evolution of contact resistance in the third stage:

[0064]

[0065] where k n is the fitting parameter. The evolution of contact resistance during the entire wear process can be expressed by the following equation:

[0066]

[0067] like Figure 5 As shown, the critical micro-motion cycle number N at point B cri There is a large dispersion in the experiment. 20 sets of experimental data were collected and the critical number of micromotion cycles N was analyzed. cri The distribution of the critical micro-motion cycle is described by the Weibull distribution. The Weibull distribution has been widely used in reliability engineering, especially for describing the distribution of the cumulative wear failure of electromechanical products. cri The probability density of can be expressed as:

[0068]

[0069] Where λ, l and c represent fitting parameters. For CuZn40 alloy, the values ​​of the fitting parameters in the contact resistance evolution model are shown in Table 3.

[0070] Table 3 Parameter values ​​in the contact resistance evolution model of CuZn40 alloy

[0071]

[0072]

[0073] like Figure 6As shown, the three-dimensional model of the upper spherical component and the bottom cylindrical component is established using the part module within the ABAQUS finite element software. In order to reduce the number of units and save calculation time, the model of the upper sphere is simplified into a small cubic area including the contact area. The two parts of the model are then assigned the material parameters of the CuZn40 alloy, including elastic modulus, Poisson's ratio, density, thermal expansion coefficient, thermal conductivity, etc. The contact between the spherical sample and the upper plane of the cylindrical sample is defined using master and slave surfaces. The surface of the spherical contact pair is set as the master surface, and the top of the plane contact pair is determined as the slave surface. The normal contact characteristic is a hard contact model, and the tangential contact behavior is determined by the friction coefficient. The finite element model uses the Q3D8 unit type for electrothermomechanical analysis. Fine meshing is performed on the contact area to obtain accurate numerical results. Coarse meshing is performed on other surrounding areas to save calculation time. The mesh of the finite element model is as follows Figure 7 As shown in Figure 1. Fixed boundary conditions are applied to the bottom surface of the plate contact pair and its potential is set to zero. A coupling relationship is established between the reference point and the top surface of the spherical contact pair. The normal force, current load, and displacement amplitude are applied to the spherical contact pair through the reference point. The loading history is shown in Figure 1. Figure 8 As shown. The normal force and current load reached their specified values ​​(normal force P = 15N, current load I = 6A) and then remained constant. The applied periodic horizontal displacement ranged from -50μm to +50μm, with a total micro-displacement of 100μm.

[0074] like Fig. 9 The figure shows the flowchart of the collaborative simulation algorithm of MATLAB-PYTHON-ABAQUS multi-software interaction. Based on this method, the electrical-thermal-mechanical coupled wear behavior in electrical contacts is simulated. ABAQUS is the main computing platform. PYTHON and MATLAB are used for parameter post-processing and updating of calculation files submitted by ABAQUS. The specific calculation process is as follows:

[0075] Step 1: Import the initial parameters into the finite element model created by ABAQUS and start the first calculation cycle. The initial parameters include the micromotion parameters (micromotion amplitude δ s , normal force P and current load I), wear parameters (wear coefficient φ and friction coefficient μ), material parameters (elastic modulus E, Poisson's ratio ν and conductivity γ e In the first calculation cycle, the current calculation increment step i and the accumulated cycle number k are set to 1.

[0076] Step 2: ABAQUS calculates a database file for each incremental step. Then, PYTHON extracts the local tangential friction stress q at each node in the contact area from the database file k and relative slip Δsk And parameters such as total contact area A.

[0077] Step 3: Import the parameters extracted in step 2 into MATLAB. MATLAB uses the formula Δh k =φ·ΔNq k Δs k Calculate the wear depth Δh of each node in the contact area k . The coordinates of the contact nodes are then modified based on the results of the wear depth. At the same time, the contact conductivity on the interface is also calculated. Based on the results of the contact resistance and contact area. The wear depth of each contact node and the contact conductivity of the contact surface are updated at each incremental step. The previous database file is set as a predefined field and a new input file is generated after changing the mesh node coordinates for the next incremental step.

[0078] Step 4: After each analysis step is calculated, the value of the current incremental step will be increased by 1. Repeat the calculation process until the value of the incremental step reaches the maximum incremental step contained in one jog cycle block.

[0079] Step 5: The algorithm repeats steps 2-4 until the jog loop block reaches the maximum number of loops and stops calculating.

[0080] like Fig.10 As shown in the figure, the comparison results of the average wear volume obtained by numerical simulation and experiment under various micro-motion cycles are shown. The maximum error between the simulation results and the experimental results is 9.77%, indicating that the simulation results of the micro-motion wear volume of CuZn40 alloy under 6A current load are reliable. The wear profile simulation results after 7000 cycles are compared with the three sets of experimental results, as shown in the figure. Fig.11 As shown. The results show that the simulation results are in good agreement with the experimental results. The critical fretting cycles corresponding to the upper and lower limits of the 95% confidence interval, as well as the maximum probability density, are selected to generate the contact resistance evolution. The contact zone temperature is simulated using the joint simulation method, and the calculated results are compared with five sets of experimental data, as shown in Fig.12 shown. Fig.12 The temperature simulations 1 and 2 (black dashed lines and black solid lines) in Graph 1 and Graph 2 represent the temperature calculation results corresponding to the upper and lower limits of the 95% confidence interval of the critical micromotion cycle, respectively. Fig.12The temperature simulation 3 (red dotted line) in Figure 3 shows the corresponding temperature calculation results under the maximum probability density of the critical micro-motion cycle. The results show that most of the experimental data are distributed within the confidence interval. The comparison shows that the temperature simulation results are in good agreement with the experimental data. This shows that this simulation method can accurately simulate the wear morphology and evolution of the wear volume in the contact area during current-carrying wear, as well as the distribution of various physical fields such as electric field, temperature field, stress and strain field, and can be used to evaluate the electrical contact state and behavior of electrical equipment under micro-motion conditions to ensure the operational reliability of electrical equipment.

[0081] The present invention establishes an electric-thermal-mechanical-wear modeling method for electrical contact under current-carrying micromotion conditions to evaluate the electrical contact behavior under micromotion conditions. Micromotion wear tests are carried out on the micromotion wear behavior under electrical contact conditions. An evolution model of contact resistance and wear coefficient is established based on the experimental results; a micromotion wear finite element model is established; an ABAQUS-PYTHON-MATLAB joint simulation method is introduced to perform cyclic iterative calculations; and finally the electric-thermal-mechanical-wear behavior of the contact area under current-carrying micromotion conditions is simulated. This simulation method can accurately simulate the wear morphology and evolution of the wear volume of the contact area during the current-carrying wear process, as well as the distribution of various physical fields such as electric field, temperature field, stress strain field, etc., and can be used to evaluate the electrical contact state and behavior of electrical equipment to ensure the operational reliability of the electrical equipment.

[0082] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

[0083] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for modeling the electrothermal wear of electrical contacts under current-carrying micro-motion conditions, characterized in that: The following steps are involved: S1: Select electrical contact material, determine material parameters and load conditions; S2: Conduct current-carrying electrical contact wear experiments to obtain the evolution law of wear coefficient and contact resistance; S3: Establish fretting wear finite element model; S4: Establish ABAQUS-PYTHON-MATLAB joint simulation method to simulate physical fields and wear evolution; S5: Compare with experimental results to verify the model and optimize parameters; In step S1, the material parameters of the electrical contact material include density ρ, elastic modulus E, Poisson's ratio ν, thermal expansion coefficient β, specific heat capacity C p , conductivity γ e and thermal conductivity k t , the load conditions include normal force P, micro-motion amplitude δ s and current load I; In step S2, the specific process of obtaining the evolution law of the wear coefficient and the contact resistance is as follows: S201: Conduct current-carrying electrical contact fretting wear experiments and use the four-wire method to measure the evolution of contact resistance with the number of fretting cycles; S202: collecting the critical number of micromotion cycles, that is, the number of micromotion cycles corresponding to a sudden increase in contact resistance; S203: characterize the probability distribution of the critical fretting cycle number using Weibull distribution; S204: Use the parabolic oxidation model to fit the evolution law of contact resistance; S205: using a surface topography instrument to measure the wear volume variation data with micro-motion cycles; S206: Calculating the wear coefficient at different cycle times according to the dissipated energy model; S207: fitting the evolution of the wear coefficient based on a power function model; S208: Establish an evolution model of the contact resistance and the wear coefficient along with the micro-motion wear cycle, so as to obtain the evolution law of the wear coefficient and the contact resistance.

2. The method for modeling the electrothermal wear of electrical contacts under current-carrying micro-motion conditions according to claim 1 is characterized in that: In step S3, the fretting wear finite element model is a three-dimensional ball-plate contact finite element model established using ABAQUS software, which is used to analyze the fretting wear under electrical contact conditions.

3. The method for modeling the electrothermal wear of electrical contacts under current-carrying micro-motion conditions according to claim 2 is characterized in that: The finite element model adopts Q3D8 unit type to perform electrothermal dynamics analysis. In the mesh of the finite element model, fixed boundary conditions are applied to the bottom surface of the plate contact pair, and its potential is set to zero.

4. The method for modeling the electrothermal wear of electrical contacts under current-carrying micro-motion conditions according to claim 3 is characterized in that: In step S4, the initial parameters and model are imported into the established ABAQUS-PYTHON-MATLAB joint simulation method to simulate the evolution of electric field, temperature field, stress-strain field and wear morphology. In this method, ABAQUS is the computing platform, and PYTHON and MATLAB are used for parameter post-processing and updating of calculation files submitted by ABAQUS.

5. The method for modeling the electrothermal wear of electrical contacts under current-carrying micro-motion conditions according to claim 4 is characterized in that: The specific calculation process of the ABAQUS-PYTHON-MATLAB joint simulation method is as follows: Step 1: Import the initial parameters into the finite element model created by ABAQUS and start the first calculation cycle. The initial parameters include micro-motion parameters, wear parameters, material parameters and calculation parameters. In the first calculation cycle, the current calculation increment i and the cumulative cycle number k are set to 1; Step 2: ABAQUS calculates the database file for each incremental step. Then, PYTHON extracts the local tangential friction stress q at each node in the contact area from the database file. k and relative slip Δs k and the total contact area A; Step 3: Import the parameters extracted in step 2 into MATLAB. MATLAB calculates the value of △h according to the formula k =φ·△Nq k △s k Calculate the wear depth Δh of each node in the contact area k ,Then the coordinates of the contact nodes are modified according to the results of the wear depth.,At the same time, the contact conductivity on the interface is also calculated.,Based on the results of the contact resistance and the contact area, the wear depth of each contact node and the contact conductivity of the contact surface are updated at each,incremental step.,The previous database file is set as a predefined field, and a new input file is,generated after changing the coordinates of the mesh nodes for the next,incremental step; Step 4: After each analysis step is calculated, the value of the current incremental step will be increased by 1, and the calculation process will be repeated until the value of the incremental step reaches the maximum incremental step contained in one micro-motion cycle block; Step 5: The algorithm repeats steps 2-4 until the jog loop block reaches the maximum number of loops and stops calculating.

6. The method for modeling the electrothermal wear of electrical contacts under current-carrying micro-motion conditions according to claim 5 is characterized in that: In step S5, the verification model and optimization parameters are specifically as follows: the wear profile and contact area temperature obtained by the simulation method are compared with the experimental results to verify the effectiveness of the method; the comparison content includes but is not limited to the wear profile, wear volume and contact area temperature rise; and the key parameters in the numerical simulation method are optimized according to the comparison results.

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