J-C damage parameter calibration method, device, equipment, medium and program product

Abstract

The invention relates to the technical field of battery testing, and discloses a J-C damage parameter calibration method, device and equipment, a medium and a program product, and the method comprises the steps: controlling a pressure head to carry out an extrusion experiment on a test sample piece until the test sample piece is damaged, and obtaining a first displacement set, a first pressure value set and a first stress value set; based on the J-C damage criterion, preset parameters are set, the pressure head model is controlled to conduct extrusion simulation on the sample piece model, and a second displacement set, a second pressure value set and a second stress value set are obtained; performing constraint condition judgment according to each displacement set, pressure value set and stress value set; if the constraint condition is not met, the preset parameter is adjusted, extrusion simulation is repeatedly conducted till the constraint condition is met, and a calibration parameter value of the preset parameter is obtained. According to the method, the data set containing sufficient data points can be obtained, the accuracy of the fitting parameters is improved, the accurate J-C damage parameters of the metal material are determined, and then the accuracy of the mechanical strength test of the battery pack is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery testing, and in particular to a calibration method, device, equipment, medium and program product for JC damage parameters. Background Art

[0002] Metals such as steel, aluminum, and copper are often used in the selection of structural parts in battery packs, and the damage and fracture of metal materials is a widely studied issue. When simulating the extrusion conditions of battery packs, it is necessary to consider the fracture of metal structural parts and their impact on internal battery cells and electrical components. Therefore, providing reasonable and accurate damage criterion parameters is of great significance to the accuracy of simulation calculations. At present, the most commonly used damage criterion for metal materials is the Johnson-Cook model (referred to as the JC damage criterion). This model mainly reflects the relationship between the fracture strain of the material and the stress triaxiality, strain rate effect, and temperature effect. The constitutive equation expression of the JC damage criterion is as follows:

[0003]

[0004] In most cases, the mechanical strength test conditions of the battery pack are room temperature, so the temperature effect can be ignored. In addition, the requirement for the extrusion condition test is that the extrusion speed of the extrusion plate is no more than 2mm / s, which is a low strain rate process, so the strain rate effect can also be ignored. Therefore, D1, D2 and D3 in the above formula are three parameters that need to be determined, that is, the relationship curve of the material's fracture strain-stress triaxiality needs to be determined. Stress triaxiality is a parameter that expresses the stress state. It can be used as a variable to characterize the plasticity and fracture damage model of the material, and plays an important role in structural strength and failure analysis.

[0005] In the prior art, the notched round bar tensile test can be used to calibrate the above three parameters. However, a round bar specimen with a certain notch radius can only determine one data point on the fracture strain-stress triaxiality curve. Too few data points will result in the three fitted parameters being unrepresentative, and therefore it is impossible to obtain accurate Johnson-Cook damage parameters for metal materials. Summary of the invention

[0006] In view of this, the present invention provides a JC damage parameter calibration method, device, equipment, medium and program product to solve the problem that the amount of test experimental data is too small to determine the accurate Johnson-Cook damage parameters of metal materials.

[0007] In a first aspect, the present invention provides a method for calibrating JC damage parameters, the method comprising:

[0008] The step of controlling the pressure head to perform an extrusion experiment on the test sample until the test sample is damaged, obtaining a first displacement set and a first pressure value set of the pressure head during the extrusion process, and a first stress value set of the test sample after the extrusion is completed;

[0009] Based on the JC damage criterion, preset parameters are set to control the indenter model to perform extrusion simulation on the sample model, and a second displacement set and a second pressure value set of the indenter model during the extrusion simulation process, and a second stress value set of the sample model after the extrusion simulation is completed are obtained, wherein the test sample corresponds to the sample model, and the indenter corresponds to the indenter model;

[0010] A step of determining a constraint condition, determining the constraint condition according to the first displacement set, the first pressure value set, the first stress value set, the second displacement set, the second pressure value set, and the second stress value set;

[0011] If the constraint conditions are not met, the preset parameters of the JC damage criterion are adjusted, and the step of controlling the indenter model to perform extrusion simulation on the sample model based on the JC damage criterion is returned until the constraint condition judgment step is judged to meet the constraint conditions and the calibrated parameter values ​​of the preset parameters are obtained.

[0012] The JC damage parameter calibration method provided in the embodiment of the present invention obtains a first displacement set, a first pressure value set and a first stress value set by performing an extrusion experiment on a test sample, performs an extrusion simulation on the sample model based on the JC damage criterion, obtains a second displacement set, a second pressure value set and a second stress value set, and performs constraint condition judgment according to each displacement set, pressure value set and stress value set. If the constraint condition is not satisfied, the preset parameters of the JC damage criterion are adjusted, and the extrusion simulation is repeated until the constraint condition is satisfied to obtain the calibration parameter value of the preset parameter. The present invention can obtain an experimental data set and a simulation data set containing sufficient data points through the combination of extrusion experiment and extrusion simulation, improve the accuracy of fitting parameters, determine the accurate Johnson-Cook damage parameters of metal materials, and thus improve the accuracy of mechanical strength testing of battery packs.

[0013] In an optional embodiment, obtaining a first displacement set and a first pressure value set of the pressure head during the extrusion process, and a first stress value set of the test sample after the extrusion is completed, includes: obtaining a first data set obtained by measuring the pressure head at a first preset time interval during the extrusion process, wherein the first data set includes multiple groups of data points, and the data points include corresponding initial displacements, initial pressure values, and initial times; taking the data point corresponding to the last pressure value of zero among the multiple initial pressure values ​​as the cutoff point, deleting the data points before and after the cutoff point in the first data set to obtain a second data set; subtracting the initial displacement corresponding to the cutoff point from the initial displacement in the second data set, and subtracting the initial time corresponding to the cutoff point from the initial time in the second data set to obtain a third data set; adding a group of data points including preset data before the starting position of the third data set to obtain a fourth data set, the fourth data set including the first pressure value set, the first displacement set, and the first time set; obtaining a first stress value set obtained by measuring a preset characteristic position of the test sample after the extrusion is completed, and the preset characteristic position is at least one.

[0014] The present invention can obtain a data set with sufficient data volume by performing multiple data collection during the test process, so as to accurately fit the parameters of the JC damage criterion. In addition, by deleting data points from the obtained data set, invalid data points in the collection process can be removed to avoid excessive data volume. At the same time, data processing is performed with the first valid data as the starting point, so that the actual change of the displacement of the indenter during the experiment and the corresponding time can be obtained, which is convenient for subsequent data analysis.

[0015] In an optional embodiment, based on the JC damage criterion, preset parameters are set, the indenter model is controlled to perform extrusion simulation on the sample model, and a second displacement set and a second pressure value set of the indenter model during the extrusion simulation, as well as a second stress value set of the sample model after the extrusion simulation are obtained, include: constructing a corresponding sample model and an indenter model according to the structural materials of the test sample and the indenter, with the indenter model close to the sample model; determining a value range of preset parameters of the constitutive equation in the JC damage criterion according to the structural material, and determining an initial value of the preset parameter based on the value range; subtracting the initial displacement corresponding to the cutoff point from the last initial displacement in the second data set to obtain a total displacement of the indenter; determining the number of data points in the second data set, and dividing the unit simulation time into a second preset time interval of the number of data points; controlling the indenter model to perform extrusion simulation on the sample model according to the total displacement, and outputting data according to the second preset time interval during the extrusion simulation to obtain a second displacement set and a second pressure value set of the indenter model; obtaining a second stress value set at a preset characteristic position on the sample model after the extrusion simulation based on the JC damage criterion.

[0016] By constructing a simulation model and setting simulation boundary conditions, the present invention can perform synchronous extrusion simulation for actual extrusion experiments and obtain simulation data that accurately corresponds to data points, thereby ensuring that parameters of the JC damage criterion can be fitted based on actual experimental data and simulation data.

[0017] In an optional embodiment, constraint condition judgment is performed based on the first displacement set, the first pressure value set, the first stress value set, the second displacement set, the second pressure value set and the second stress value set, including: obtaining a first displacement pressure curve based on the first displacement set and the first pressure value set, and obtaining a second displacement pressure curve based on the second displacement set and the second pressure value set, comparing the first displacement pressure curve and the second displacement pressure curve to obtain the Euclidean distance; judging whether the Euclidean distance is less than a preset distance threshold, if the Euclidean distance is less than the preset distance threshold, calculating the average error of the extrusion experiment and the extrusion simulation based on the first stress value set and the second stress value set; judging whether the average error is less than a preset error threshold, if the average error is not less than the preset error threshold, calculating the single error of each preset feature position, and judging whether the maximum single error is less than the preset error threshold.

[0018] The present invention judges the Euclidean distance, average error and single error in turn, can optimize the JC damage criterion parameters through an optimization method of progressively increasing constraint conditions, and evaluates the optimization results, so that the accuracy of the JC damage criterion parameters is gradually improved. At the same time, iterative calculations are performed using fewer constraint conditions in the early stage, and then other constraint conditions are gradually added, which can improve the optimization solution efficiency.

[0019] In an optional embodiment, if the constraint condition is not met, the preset parameters of the JC damage criterion are adjusted, and the step of controlling the indenter model to perform extrusion simulation on the sample model based on the JC damage criterion is returned until the constraint condition is met and the calibration parameter value of the preset parameter is obtained, including: based on the genetic algorithm, the value range of the preset parameter is binary-encoded according to the preset accuracy to obtain a binary coded value set of the preset parameter; if the Euclidean distance is not less than the preset distance threshold, the preset parameter is adjusted based on the binary coded value set, and the step of controlling the indenter model to perform extrusion simulation on the sample model based on the JC damage criterion is returned; if the maximum single error is not less than the preset error threshold, the preset parameter is adjusted based on the binary coded value set, and the step of controlling the indenter model to perform extrusion simulation on the sample model based on the JC damage criterion is returned; if the average error is less than the preset error threshold, the constraint condition is met, and the calibration parameter value of the preset parameter is determined according to the adjusted binary coded value.

[0020] The present invention can provide binary coded numbers with higher accuracy by constructing a genetic algorithm optimization model, and then judge the adaptability of the parameter values ​​corresponding to each binary coded number to the JC damage criterion according to the fitness screening within the algorithm, so as to determine the most accurate parameter value through step-by-step optimization.

[0021] In a second aspect, the present invention provides a calibration device for JC damage parameters, the device comprising: a first parameter acquisition module, used to control the pressure head to perform an extrusion experiment on a test sample until the test sample is damaged, and obtain a first displacement set and a first pressure value set of the pressure head during the extrusion process, and a first stress value set of the test sample after the extrusion is completed; a second parameter acquisition module, used to set preset parameters based on the JC damage criterion, control the pressure head model to perform extrusion simulation on the sample model, and obtain a second displacement set and a second pressure value set of the pressure head model during the extrusion simulation, and a second stress value set of the sample model after the extrusion simulation is completed. The present invention relates to a method for determining a constraint condition of a test piece and a test piece corresponding to a test piece model, wherein the test piece corresponds to the test piece model, and the indenter corresponds to the indenter model; a constraint condition judgment module, which is used for the constraint condition judgment step, and performs constraint condition judgment according to the first displacement set, the first pressure value set, the first stress value set, the second displacement set, the second pressure value set, and the second stress value set; and a parameter calibration module, which is used for adjusting the preset parameters of the JC damage criterion if the constraint condition is not satisfied, and returning to the step of controlling the indenter model to perform extrusion simulation on the test piece model based on the JC damage criterion, until the constraint condition judgment step obtains a judgment that the constraint condition is satisfied, and obtains the calibration parameter value of the preset parameter.

[0022] In a third aspect, the present invention provides a computer device, comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the JC damage parameter calibration method of the first aspect or any corresponding embodiment thereof by executing the computer instructions.

[0023] In a fourth aspect, the present invention provides a computer-readable storage medium having computer instructions stored thereon, the computer instructions being used to enable a computer to execute the JC damage parameter calibration method of the first aspect or any corresponding embodiment thereof.

[0024] In a fifth aspect, the present invention provides a computer program product, comprising computer instructions for causing a computer to execute the JC damage parameter calibration method of the first aspect or any corresponding embodiment thereof.

[0025] In a sixth aspect, the present invention provides a method for testing the mechanical strength of a battery pack, determining a JC damage criterion according to a calibration parameter value determined by the JC damage parameter calibration method of the first aspect or any corresponding embodiment thereof, and simulating an extrusion condition of the battery pack based on the JC damage criterion to test the mechanical strength of the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 is a flow chart of a method for calibrating JC damage parameters according to an embodiment of the present invention;

[0028] Figure 2 is a schematic diagram of a test sample of a calibration method for JC damage parameters according to an embodiment of the present invention;

[0029] Figure 3 is a schematic diagram of characteristic positions of test samples according to a method for calibrating JC damage parameters according to an embodiment of the present invention;

[0030] Figure 4 is a schematic diagram of a sample model of a JC damage parameter calibration method according to an embodiment of the present invention;

[0031] Figure 5 is a flow chart of another JC damage parameter calibration method according to an embodiment of the present invention;

[0032] Figure 6 is a specific flow chart of another JC damage parameter calibration method according to an embodiment of the present invention;

[0033] Figure 7 is a schematic diagram of a first displacement pressure curve according to another JC damage parameter calibration method according to an embodiment of the present invention;

[0034] Figure 8 is a schematic diagram of a second displacement pressure curve of another JC damage parameter calibration method according to an embodiment of the present invention;

[0035] Fig. 9 is a schematic diagram of a parameter inversion and optimization process of another JC damage parameter calibration method according to an embodiment of the present invention;

[0036] Fig.10is a schematic diagram of a genetic algorithm optimization process of another JC damage parameter calibration method according to an embodiment of the present invention;

[0037] Fig.11 is a structural block diagram of a device for calibrating JC damage parameters according to an embodiment of the present invention;

[0038] Fig.12 It is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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 those skilled in the art without creative work are within the scope of protection of the present invention.

[0040] The embodiment of the present invention is applicable to the scenario of mechanical strength testing of battery packs based on the JC damage criterion, taking the battery pack of Al6061 metal material (a standard grade of Al-Mg-Si deformable heat-treatable aluminum alloy) as an example. The embodiment of the present invention provides a calibration method of JC damage parameters, which obtains multiple data points by combining simulation and experiment to achieve the effect of improving the fitting accuracy of JC damage parameters.

[0041] According to an embodiment of the present invention, an embodiment of a method for calibrating JC damage parameters is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0042] In this embodiment, a JC damage parameter calibration method is provided, which can be used in mobile terminals, such as computers, etc. Figure 1 FIG. 1 is a flow chart of a method for calibrating JC damage parameters according to an embodiment of the present invention. Figure 1 As shown, the process includes the following steps:

[0043] Step S101 is a step of controlling the indenter to perform an extrusion experiment on the test sample until the test sample is damaged, obtaining a first displacement set and a first pressure value set of the indenter during the extrusion process, and a first stress value set of the test sample after the extrusion is completed.

[0044] Specifically, in the embodiment of the present invention, the experimenter pre-made a non-standard test sample made of Al6061 material to conduct an actual extrusion experiment. Figure 2 As shown, the test sample size is 250mm×25mm×25mm, the thickness is 2mm, and the sample is subjected to a three-point bending test on a universal testing machine. The test sample ( Figure 2 The two ends of the aluminum square tube are completely fixed, and the cylindrical indenter is pressed vertically downward at a speed of 0.1 mm / s directly above the aluminum square tube. The load boundary is applied in the following way: Figure 3 As shown, the movement of the pressure head is stopped until a clear visible fracture occurs on the aluminum square tube, wherein L0 represents the remaining length of the aluminum square tube after removing the length of the clamp holding position.

[0045] In some optional implementations, during the extrusion experiment of the pressure head crushing the aluminum square tube, the displacement data of the pressure head and the applied pressure value are collected in real time at preset time intervals, so as to output the time-displacement-pressure data points after the extrusion experiment is completed. The embodiment of the present invention can obtain the first displacement set and the first pressure value set of the pressure head. Figure 3 The stress values ​​of the five characteristic positions ①-⑤ shown in the figure are measured, and the stress values ​​of the five characteristic positions are obtained after the extrusion experiment to obtain the first stress value set. The number of data points in the obtained first displacement set and the first pressure value set is the same, the corresponding time of each data point is consistent, and the number of data points in the first stress value set is the same as the number of characteristic positions.

[0046] Step S102, based on the JC damage criterion, setting preset parameters, controlling the indenter model to perform extrusion simulation on the sample model, and obtaining a second displacement set and a second pressure value set of the indenter model during the extrusion simulation, and a second stress value set of the sample model after the extrusion simulation, wherein the test sample corresponds to the sample model, and the indenter corresponds to the indenter model.

[0047] Specifically, in the embodiment of the present invention, Abaqus simulation software is used to establish a sample model with the same size and a corresponding indenter model according to the actual extrusion experiment, such as Figure 4 As shown, the initial position of the indenter model is close to the sample model of the aluminum square tube, so as to perform extrusion simulation under the same working conditions. In the simulated extrusion process, the value range of the preset parameters D1, D2 and D3 in the JC damage criterion is determined according to the material of the test sample, and the initial value of each parameter is randomly set within the value range. The constitutive equation of the JC damage criterion is determined according to the initial value, and then the indenter model is controlled to perform extrusion simulation on the sample model vertically downward at a uniform speed within a unit simulation time, such as 1s, and the second displacement set and the second pressure value set of the indenter model are obtained in real time during the extrusion simulation based on the JC damage criterion, and the second stress value set of the five characteristic positions in the sample model is obtained after the extrusion simulation is completed.

[0048] In some optional embodiments, in order to make the actual extrusion experiment and the extrusion simulation correspond as much as possible, the embodiment of the present invention determines the effective displacement of the punch according to the first displacement set of the punch, thereby controlling the punch model to reach the corresponding effective displacement within 1 second in the extrusion simulation, and at the same time performs data sampling according to the number of data points in the first displacement set to ensure that the number of data points in the second displacement set and the second pressure value set is the same as that in the first displacement set and the first pressure value set, so that data fitting can be performed according to the actual experimental data and the simulation experiment parameters.

[0049] In some optional implementations, in order to make the extrusion simulation periodic, the embodiment of the present invention uses Python language to implement the extrusion simulation process with script commands. In the script, the three parameters D1, D2, and D3 need to be set as variables and placed at the front of the script, named D1, D2, and D3 respectively, and the initial value is set to At the same time, these three variables will be referenced as parameter values ​​in the command for setting the material JC damage criterion parameters. The script has the function of automatic post-processing and can automatically output the second displacement set, the second pressure value set and the second stress value set.

[0050] Step S103, a step of determining a constraint condition, determines the constraint condition based on the first displacement set, the first pressure value set, the first stress value set, the second displacement set, the second pressure value set, and the second stress value set.

[0051] Specifically, in an embodiment of the present invention, a progressive constraint condition is constructed according to the displacement and pressure value of the pressure head and the stress value of the test sample, and the progressive constraint condition is used to judge whether the values ​​of D1, D2 and D3 in the JC damage criterion are reasonable. Among them, in order to improve the consistency of the extrusion simulation and the extrusion experiment, the first layer of constraint conditions is constructed according to the displacement data and the pressure value data, and the first layer of constraint conditions are judged according to the first displacement set, the first pressure value set, the second displacement set and the second pressure value set. If the first layer of constraint conditions are met, it is proved that the simulation results and the experimental results are close, then the second layer of constraint conditions are constructed according to the pressure value data of the five characteristic positions, and the second layer of constraint conditions are judged according to the first stress value set and the second stress value set. If the second layer of constraint conditions are met, it is proved that the stress values ​​of the five characteristic positions in the simulation results and the experimental results are consistent, and the optimization results of the three parameters D1, D2 and D3 are reasonable, but if the second layer of constraint conditions are not met, it is necessary to increase the optimization conditions. The embodiment of the present invention constructs the third-level constraint condition based on the pressure value data of a single characteristic position, and judges the third-level constraint condition based on the stress value corresponding to the characteristic position in the first stress value set and the second stress value set. If the third-level constraint condition is met, it proves that the optimization results of the three parameters D1, D2 and D3 are reasonable.

[0052] Step S104, if the constraint condition is not met, the preset parameters of the JC damage criterion are adjusted, and the step of controlling the indenter model to perform extrusion simulation on the sample model based on the JC damage criterion is returned until the constraint condition judgment step is judged to meet the constraint condition and the calibration parameter value of the preset parameter is obtained.

[0053] Specifically, in an embodiment of the present invention, if the first-level constraint condition or the third-level constraint condition is not met, the parameter values ​​of the three parameters D1, D2 and D3 in the JC damage criterion are adjusted, and the adjustment range cannot exceed the corresponding value range. After the parameter value is adjusted, the parameter inversion is performed again through the extrusion simulation, and the progressive constraint condition is judged again after the simulation until the second-level constraint condition is met. When the constraint conditions are met, the parameter values ​​of the three parameters D1, D2 and D3 in the constitutive equation of the JC damage criterion based on the last extrusion simulation are used as the corresponding calibration parameter values. In the subsequent battery pack mechanical strength test process, the constitutive equation of the JC loss criterion can be directly determined according to the calibration parameter value to achieve accurate mechanical strength testing.

[0054] The JC damage parameter calibration method provided in the embodiment of the present invention obtains a first displacement set, a first pressure value set and a first stress value set by performing an extrusion experiment on a test sample, performs an extrusion simulation on the sample model based on the JC damage criterion, obtains a second displacement set, a second pressure value set and a second stress value set, and performs constraint condition judgment according to each displacement set, pressure value set and stress value set. If the constraint condition is not satisfied, the preset parameters of the JC damage criterion are adjusted, and the extrusion simulation is repeated until the constraint condition is satisfied to obtain the calibration parameter value of the preset parameter. The present invention can obtain an experimental data set and a simulation data set containing sufficient data points through the combination of extrusion experiment and extrusion simulation, improve the accuracy of fitting parameters, determine the accurate Johnson-Cook damage parameters of metal materials, and thus improve the accuracy of mechanical strength testing of battery packs.

[0055] In this embodiment, a JC damage parameter calibration method is provided, which can be used in the above-mentioned mobile terminal, such as a computer, etc. Figure 5 FIG. 1 is a flow chart of a method for calibrating JC damage parameters according to an embodiment of the present invention. Figure 5 As shown, the process includes the following steps:

[0056] Step S501 is a step of controlling the indenter to perform an extrusion experiment on the test sample until the test sample is damaged, obtaining a first displacement set and a first pressure value set of the indenter during the extrusion process, and a first stress value set of the test sample after the extrusion is completed.

[0057] Specifically, the above step S501 includes:

[0058] Step S5011, obtaining a first data set obtained by measuring the pressure head at a first preset time interval during the extrusion process, wherein the first data set includes multiple groups of data points, and the data points include corresponding initial displacements, initial pressure values ​​and initial times.

[0059] Specifically, in the embodiment of the present invention, during the process of controlling the pressure head to perform an extrusion experiment on the sample model, the pressure head gradually sticks to the middle position point of the test sample from far to near, and then presses down vertically at the middle position point of the sample model, and the test sample gradually begins to deform until it breaks. In this process, the displacement and pressure values ​​of the pressure head are collected in real time according to the sampling time interval to obtain the first data set, so the first data set contains multiple groups of data points, each group of data points contains the corresponding initial displacement s i , initial pressure value F i and initial time t i .

[0060] Step S5012: taking the data point corresponding to the last pressure value of zero among the multiple initial pressure values ​​as the cutoff point, deleting the data points before and after the cutoff point in the first data set, and obtaining a second data set.

[0061] Specifically, in the embodiment of the present invention, in the actual extrusion experiment, the pressure head gradually comes into contact with the test sample from far to near, so at the initial moment, the pressure head and the test sample are not in contact, and the pressure value applied at this time is 0. Therefore, there are multiple data points with the initial pressure value of 0 in the first data set. In order to reduce the amount of invalid data, the embodiment of the present invention uses the data point corresponding to the last pressure value of zero among the multiple initial pressure values ​​as the cutoff point, deletes the data points before and after the cutoff point in the first data set, and obtains the second data set, that is, the F corresponding to the cutoff point in the first data set -1 and F -1 The previous initial pressure value and the corresponding s -1 and -1 The previous initial displacement and the corresponding t -1 and t -1 All previous initial times are deleted, and only valid data points are retained. The number of data points in the second data set obtained at this time is recorded as n, and the time, displacement and pressure values ​​corresponding to each data point are s respectively. m 、F m and t m , m=1,2,3,…,n.

[0062] Step S5013: subtract the initial displacement corresponding to the cutoff point from the initial displacement in the second data set, and subtract the initial time corresponding to the cutoff point from the initial time in the second data set to obtain a third data set.

[0063] Specifically, in the embodiment of the present invention, the remaining initial pressure values ​​in the second data set gradually increase after the pressure head and the test sample come into contact, and after the invalid data are deleted, the accumulation starts from zero. However, the displacement data and time data are accumulated from the beginning of the movement of the pressure head. Therefore, after the invalid data are deleted, the displacement and time have accumulated to a certain data. Therefore, in order to unify the displacement data and time data to accumulate from zero, the embodiment of the present invention sets all the initial displacement s in the second data set to zero. i 1 Subtract the initial displacement s corresponding to the cutoff point -1 , and all initial times t -1 Subtract the initial time t corresponding to the cutoff point -1 1 , the initial pressure value remains unchanged, and the third data set is obtained. The calculation formula is as follows:

[0064]

[0065] Step S5014, adding a group of data points containing preset data before the starting position of the third data set to obtain a fourth data set, the fourth data set including a first pressure value set, a first displacement set and a first time set.

[0066] Specifically, in the embodiment of the present invention, in order to characterize that the extrusion experiment starts from the moment when the indenter and the test sample just come into contact, a group of data points with a value of 0 is added before the starting position of the third data set, that is, t0 is added before n data points in the third data set. 1 =0,s0 1 =0 and F0 1 =0, a fourth data set is obtained, wherein the fourth data set has n+1 data points, including the first pressure value set The first displacement set And the first time collection There are n+1 data in each set.

[0067] Step S5015, obtaining a first stress value set obtained by measuring a preset characteristic position of the test sample after the extrusion is completed, and there is at least one preset characteristic position.

[0068] Specifically, in the embodiment of the present invention, Figure 3 As shown in FIG. 1 , based on the symmetry of the test sample, five characteristic positions are selected on the same side of the test sample, which is only an example and is not limited to this. The stress values ​​of the five characteristic positions after the extrusion experiment are measured by deploying strain gauges at each characteristic position to obtain a first stress value set.

[0069] Step S502, based on the JC damage criterion, setting preset parameters, controlling the indenter model to perform extrusion simulation on the sample model, and obtaining a second displacement set and a second pressure value set of the indenter model during the extrusion simulation, and a second stress value set of the sample model after the extrusion simulation, wherein the test sample corresponds to the sample model, and the indenter corresponds to the indenter model.

[0070] Specifically, the above step S502 includes:

[0071] Step S5021, construct corresponding sample model and indenter model according to the structural materials of the test sample and the indenter, and the indenter model is closely attached to the sample model.

[0072] Specifically, in an embodiment of the present invention, Abaqus simulation calculation software is used to construct a sample model consistent with the test sample, wherein the sample model is an aluminum square tube, and its material parameters include: density, elastic modulus, Poisson's ratio, yield strength, tensile strength, and elongation at break; structural parameters: the sample size is 250mm×25mm×25mm, and the thickness is 2mm.

[0073] Step S5022, determining the value range of the preset parameters of the constitutive equation in the JC damage criterion according to the structural material, and determining the initial value of the preset parameter based on the value range.

[0074] Specifically, in the embodiment of the present invention, the value ranges of D1, D2 and D3 in the constitutive equation of the JC damage criterion are determined according to the structural material, which are (-1, 0), (0, 2) and (0, 1) respectively, and the more reasonable initial parameter values ​​are determined empirically in the value ranges of D1, D2 and D3, which are set to D1, D2 and D3 respectively. 0 、D2 0 and D3 0 , the other parameters in the constitutive equation are known and accurate.

[0075] Step S5023, subtracting the initial displacement corresponding to the cutoff point from the last initial displacement in the second data set to obtain the total displacement of the indenter.

[0076] Specifically, in the embodiment of the present invention, in order to realize the extrusion simulation synchronized with the actual extrusion experiment, it is necessary to set the simulation boundary conditions. Since the extrusion experiment is a process of controlling the pressing of the ram, the embodiment of the present invention controls the pressing process of the ram model in the extrusion simulation according to the total displacement of the ram in the actual extrusion experiment. Specifically, the last initial displacement s in the second data set is set to n Subtract the initial displacement s corresponding to the cutoff point -1 , the total displacement s of the pressure head is obtained, which is equivalent to the last displacement value in the first displacement set. The calculation formula is as follows:

[0077]

[0078] Step S5024, determining the number of data points of the second data set, and dividing the unit simulation time into a second preset time interval of the number of data points.

[0079] Specifically, in an embodiment of the present invention, in order to ensure that the experimental data obtained from the actual extrusion experiment and the simulation data obtained from the extrusion simulation correspond to each other, the embodiment of the present invention determines the number of data points n in the second data set, and then divides the unit simulation time 1s into n preset time intervals Δt, that is, Δt=1 / n, and then collects data for the simulation process according to the preset time interval Δt, which can ensure that the number of data points obtained is n+1, which corresponds to the experimental data.

[0080] Step S5025, controlling the indenter model to perform extrusion simulation on the sample model according to the total displacement, and outputting data according to a second preset time interval during the extrusion simulation process, to obtain a second displacement set and a second pressure value set of the indenter model.

[0081] Specifically, in the embodiment of the present invention, the total displacement of the indenter model within the unit simulation time of 1s is s, so the indenter model is controlled to move vertically downward at a uniform speed within the unit simulation time of 1s, and stops pressing down after reaching the displacement s. At the same time, data collection and data output are performed according to Δt after the pressing starts, and the second displacement set is obtained. and a second pressure value set The total number of data points is n+1.

[0082] Step S5026, based on the JC damage criterion, a second set of stress values ​​at a preset characteristic position on the sample model is obtained after the extrusion simulation is completed.

[0083] Specifically, in the embodiment of the present invention, during the extrusion simulation, the JC damage criterion can describe the damage behavior of the sample model during the dynamic impact process, reflect the relationship between the material fracture strain and the stress triaxiality, thereby determining the stress values ​​of the five characteristic positions on the sample model, and obtaining the second stress value set after the extrusion simulation is completed. The specific process is a conventional technical means in this field and will not be described in detail here.

[0084] Step S503, the step of determining the constraint conditions, determines the constraint conditions according to the first displacement set, the first pressure value set, the first stress value set, the second displacement set, the second pressure value set and the second stress value set. Figure 1 Step S103 of the illustrated embodiment will not be described in detail here.

[0085] Step S504: If the constraint condition is not satisfied, the preset parameters of the JC damage criterion are adjusted, and the process returns to the step of controlling the indenter model to perform extrusion simulation on the sample model based on the JC damage criterion, until the constraint condition judgment step is satisfied, and the calibrated parameter values ​​of the preset parameters are obtained. Figure 1 Step S104 of the illustrated embodiment will not be described in detail here.

[0086] The JC damage parameter calibration method provided in the embodiment of the present invention obtains a first displacement set, a first pressure value set and a first stress value set by performing an extrusion experiment on a test sample, performs an extrusion simulation on the sample model based on the JC damage criterion, obtains a second displacement set, a second pressure value set and a second stress value set, and performs constraint condition judgment according to each displacement set, pressure value set and stress value set. If the constraint condition is not satisfied, the preset parameters of the JC damage criterion are adjusted, and the extrusion simulation is repeated until the constraint condition is satisfied to obtain the calibration parameter value of the preset parameter. The present invention can obtain an experimental data set and a simulation data set containing sufficient data points through the combination of extrusion experiment and extrusion simulation, improve the accuracy of fitting parameters, determine the accurate Johnson-Cook damage parameters of metal materials, and thus improve the accuracy of mechanical strength testing of battery packs.

[0087] In this embodiment, a JC damage parameter calibration method is provided, which can be used in the above-mentioned mobile terminal, such as a computer, etc. Figure 6 is a flow chart of a method for determining the failure risk of a battery pack according to an embodiment of the present invention. Figure 6 As shown, the process includes the following steps:

[0088] Step S601, control the indenter to perform an extrusion test on the test sample until the test sample is damaged, obtain the first displacement set and the first pressure value set of the indenter during the extrusion process, and the first stress value set of the test sample after the extrusion is completed. For details, please refer to Figure 5 Step S501 of the illustrated embodiment will not be described in detail here.

[0089] Step S602, based on the JC damage criterion, set preset parameters, control the indenter model to perform extrusion simulation on the sample model, and obtain the second displacement set and the second pressure value set of the indenter model during the extrusion simulation, and the second stress value set of the sample model after the extrusion simulation, wherein the test sample corresponds to the sample model, and the indenter corresponds to the indenter model. For details, please refer to Figure 5 Step S502 of the illustrated embodiment will not be described in detail here.

[0090] Step S603, a step of determining a constraint condition, determines the constraint condition based on the first displacement set, the first pressure value set, the first stress value set, the second displacement set, the second pressure value set, and the second stress value set.

[0091] Specifically, the above step S603 includes:

[0092] Step S6031, obtaining a first displacement pressure curve according to the first displacement set and the first pressure value set, and obtaining a second displacement pressure curve according to the second displacement set and the second pressure value set, and comparing the first displacement pressure curve and the second displacement pressure curve to obtain a Euclidean distance.

[0093] Specifically, in the embodiment of the present invention, the first displacement set and the first pressure value set correspond to the state change of the pressure head during the actual extrusion experiment, and the second displacement set and the second pressure value set correspond to the state change of the pressure head model during the extrusion simulation, both of which are described by displacement-pressure curves, wherein the first displacement-pressure curve is as follows: Figure 7 As shown, the second displacement pressure curve is Figure 8 As shown. Fig. 9 As shown, the similarity between the first displacement pressure curve and the second displacement pressure curve is calculated. Since the number of data points of the two curves is the same, both are n+1, and the horizontal coordinate curves are the same, both are [0, s], and the corresponding data points have the same horizontal coordinates, the Euclidean distance (Euclidean Distance) of the two curves is calculated, denoted as D, and the calculation formula is as follows:

[0094]

[0095] Step S6032, determining whether the Euclidean distance is less than a preset distance threshold, if the Euclidean distance is less than the preset distance threshold, calculating the average error of the extrusion experiment and the extrusion simulation according to the first stress value set and the second stress value set.

[0096] Specifically, in the embodiment of the present invention, the smaller the value of D is, the closer the simulation results are to the experimental results, and the more reasonable the parameter settings of D1, D2, and D3 are. Therefore, judging whether the Euclidean distance is less than the preset distance threshold is the first-level constraint condition. Fig. 9 As shown, the present invention adopts genetic algorithm to perform parameter inversion and optimization process, and automatically simulates and outputs D value by optimizing the three parameter values ​​D1, D2 and D3 in Python script through multiple iterations, so that D value reaches a smaller target value D t At this time, the values ​​of the three parameters D1, D2, and D3 are the inversion results.

[0097] In some optional implementations, after determining the parameter inversion results, the embodiment of the present invention further optimizes the parameter values ​​of the three parameters D1, D2, and D3 by comparing the stress values ​​obtained from the extrusion experiment and the extrusion simulation. The stress values ​​of the five characteristic positions are measured in the extrusion experiment and the extrusion simulation respectively to obtain the first stress value set and the second stress value set The average error between the extrusion test and extrusion simulation strain results is calculated based on the two stress value sets, denoted as AEV, and the calculation formula is as follows:

[0098]

[0099] Step S6033, determine whether the average error is less than the preset error threshold. If the average error is not less than the preset error threshold, calculate the single error of each preset feature position and determine whether the maximum single error is less than the preset error threshold.

[0100] Specifically, in the embodiment of the present invention, the average error AEV of the extrusion test and extrusion simulation strain results is judged as the second-level constraint condition, and the error threshold is set to 10%, but not limited to this. After each extrusion simulation, it is determined whether the average error of the five preset positions is less than the error threshold of 10%, so as to determine whether the optimization results of the three parameters D1, D2, and D3 are reasonable. If AEV>10%, it is considered that the optimization result is not good, and it is necessary to add optimization constraints and re-perform parameter inversion.

[0101] In some optional implementations, the embodiment of the present invention calculates the single error of each preset feature position, recorded as EV, and takes the stress error of position a with the largest single error among the five feature positions as the added third-level constraint condition to determine whether the EV is less than the preset error of 10%. The calculation formula of EV is as follows:

[0102]

[0103] Step S604, if the constraint condition is not met, the preset parameters of the JC damage criterion are adjusted, and the step of controlling the indenter model to perform extrusion simulation on the sample model based on the JC damage criterion is returned until the constraint condition judgment step is judged to meet the constraint condition and the calibration parameter value of the preset parameter is obtained.

[0104] Specifically, the above step S604 includes:

[0105] Step S6041: Binary encode the value range of the preset parameter according to the preset precision based on the genetic algorithm to obtain a binary coded value set of the preset parameter.

[0106] Specifically, in the embodiment of the present invention, the genetic algorithm optimization model is used to optimize the parameter values ​​of the three parameters D1, D2 and D3 in the JC damage accuracy, and the optimization variables are D1, D2 and D3, and the value ranges are (-1, 0), (0, 2) and (0, 1), respectively, with an accuracy of 0.01, and binary coding is used to represent all possible values ​​of the parameters in the interval. Among them, the length N of the binary code should satisfy the following formula:

[0107]

[0108] Among them, l is the interval length of the value range. After substituting the interval length 1 corresponding to the value range of D1 into the above formula, the corresponding binary code length is 7, which means that the 7-bit binary code can represent all values ​​in the range. Similarly, the binary code lengths corresponding to D2 and D3 are 8 and 7 respectively. Therefore, the length of a completed chromosome code is 7+8+7=22. This chromosome code also contains the parameter values ​​of three parameters. For example, 0000000 / 00000000 / 0000000 means D1=-0.99, D2=0.01, and D3=0.01. After determining the chromosome structure, a population of size g can be initialized: it contains g 22-bit binary code numbers, and the fitness of each individual p i =f(x i ) / ∑f(x i ), where x i The real values ​​of the three variables after decoding each 22-bit code, x i Actually it is a 1×3 row vector.

[0109] In some optional implementations, the genetic algorithm selects individuals that can participate in replication and genetic evolution according to the fitness of each individual, and the screening strategy selects a roulette strategy, and the size of the roulette wheel is divided according to p i The size of the individual is used to divide the population. When performing the copy operation on the individual, a random number within (0,1) is generated. The copied individual is determined according to the position of the generated random number in the roulette wheel. The new parent population is obtained by looping g times. After obtaining the parent population, genetic operations are performed with a crossover probability of 0.6 and a mutation probability of 0.1. The crossover operation is to crossover with adjacent individuals according to probability, and the mutation operation is to mutate each individual after the crossover according to probability, wherein the position and the number of bits of the crossover and mutation are all random. The sub-class population after one round of iteration becomes the new parent population, and then the next round of iteration is performed. The embodiment of the present invention uses the first-layer constraint condition as the condition for terminating the iteration, and the process is as follows Fig.10 As shown, the condition for terminating the iteration is set to D <D t When this condition is met, a population of f(x) that all meet the target condition will be obtained. Finally, the best value can be selected from them.

[0110] Step S6042, if the Euclidean distance is not less than the preset distance threshold, the preset parameters are adjusted based on the binary coded value set, and the process returns to the step of controlling the indenter model to perform extrusion simulation on the sample model based on the JC damage criterion.

[0111] Specifically, in the embodiment of the present invention, if the termination condition is not met, that is, the Euclidean distance D is not less than the preset distance threshold D t , then the parameter values ​​of D1, D2 and D3 are adjusted based on the binary coded value set. The specific adjustment process is determined by the internal algorithm of the genetic algorithm and will not be described in detail here. Fig. 9 As shown, repeat the iteration until D <D t .

[0112] Step S6043, if the maximum single error is not less than the preset error threshold, the preset parameters are adjusted based on the binary coded value set, and the process returns to the step of controlling the indenter model to perform extrusion simulation on the sample model based on the JC damage criterion.

[0113] Specifically, in the embodiment of the present invention, Fig. 9 As shown in the figure, if EV≤10%, the optimization results of the three parameters D1, D2, and D3 are reasonable, and the parameter calibration process ends. However, if EV>10%, the optimization result is considered to be poor, and the parameter inversion and optimization are repeated to obtain the optimization results of the three parameters, and the average error judgment is repeated until the second-level constraint condition AEV≤10% is met.

[0114] Step S6044: If the average error is less than the preset error threshold, the constraint condition is met, and the calibration parameter value of the preset parameter is determined according to the adjusted binary code value.

[0115] Specifically, in the embodiment of the present invention, Fig. 9 As shown in the figure, if AEV≤10%, it is considered that the strain values ​​of the five characteristic positions of the experimental and simulation calculation results are consistent with each other, the optimization results of the three parameters D1, D2, and D3 are reasonable, and the parameter calibration process is completed.

[0116] The JC damage parameter calibration method provided in the embodiment of the present invention obtains a first displacement set, a first pressure value set and a first stress value set by performing an extrusion experiment on a test sample, performs an extrusion simulation on the sample model based on the JC damage criterion, obtains a second displacement set, a second pressure value set and a second stress value set, and performs constraint condition judgment according to each displacement set, pressure value set and stress value set. If the constraint condition is not satisfied, the preset parameters of the JC damage criterion are adjusted, and the extrusion simulation is repeated until the constraint condition is satisfied to obtain the calibration parameter value of the preset parameter. The present invention can obtain an experimental data set and a simulation data set containing sufficient data points through the combination of extrusion experiment and extrusion simulation, improve the accuracy of fitting parameters, determine the accurate Johnson-Cook damage parameters of metal materials, and thus improve the accuracy of mechanical strength testing of battery packs.

[0117] In this embodiment, a calibration device for JC damage parameters is also provided, which is used to implement the above embodiments and preferred implementation modes, and the descriptions that have been made will not be repeated. As used below, the term "module" can be a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceivable.

[0118] This embodiment provides a JC damage parameter calibration device, such as Fig.11 As shown, including:

[0119] The first parameter acquisition module 1101 is used to control the step of controlling the punch to perform an extrusion experiment on the test sample until the test sample is damaged, and to obtain a first displacement set and a first pressure value set of the punch during the extrusion process, and a first stress value set of the test sample after the extrusion is completed.

[0120] The second parameter acquisition module 1102 is used to set preset parameters based on the JC damage criterion, control the indenter model to perform extrusion simulation on the sample model, and obtain a second displacement set and a second pressure value set of the indenter model during the extrusion simulation, and a second stress value set of the sample model after the extrusion simulation, wherein the test sample corresponds to the sample model, and the indenter corresponds to the indenter model.

[0121] The constraint condition judgment module 1103, a constraint condition judgment step, is used to judge the constraint condition according to the first displacement set, the first pressure value set, the first stress value set, the second displacement set, the second pressure value set and the second stress value set.

[0122] The parameter calibration module 1104 is used to adjust the preset parameters of the JC damage criterion if the constraint conditions are not met, and return to the step of controlling the indenter model to perform extrusion simulation on the sample model based on the JC damage criterion, until the constraint condition judgment step is judged to meet the constraint conditions, and the calibration parameter value of the preset parameter is obtained.

[0123] In some optional implementations, the first parameter acquisition module 1101 includes:

[0124] The first initial parameter acquisition unit is used to acquire a first data set obtained by measuring the pressure head at a first preset time interval during the extrusion process, wherein the first data set includes multiple groups of data points, and the data points include corresponding initial displacements, initial pressure values ​​and initial times.

[0125] The data deletion unit is used to use the data point corresponding to the last zero pressure value among the multiple initial pressure values ​​as the cutoff point, delete the data points before and after the cutoff point in the first data set, and obtain the second data set.

[0126] The data adjustment unit is used to subtract the initial displacement corresponding to the cutoff point from the initial displacement in the second data set, and to subtract the initial time corresponding to the cutoff point from the initial time in the second data set, so as to obtain a third data set.

[0127] The data adding unit is used to add a group of data points containing preset data before the starting position of the third data set to obtain a fourth data set, wherein the fourth data set includes a first pressure value set, a first displacement set and a first time set.

[0128] The second initial parameter acquisition unit is used to acquire a first stress value set obtained by measuring a preset characteristic position of the test sample after the extrusion is completed, and there is at least one preset characteristic position.

[0129] In some optional implementations, the second parameter acquisition module 1102 includes:

[0130] The model building unit is used to build corresponding sample model and indenter model according to the structural materials of the test sample and the indenter, and the indenter model is closely attached to the sample model.

[0131] The parameter setting unit is used to determine the value range of the preset parameters of the constitutive equation in the JC damage criterion according to the structural material, and determine the initial value of the preset parameter based on the value range.

[0132] The first boundary condition setting unit is used to subtract the initial displacement corresponding to the cutoff point from the last initial displacement in the second data set to obtain the total displacement of the pressure head.

[0133] The second boundary condition setting unit is used to determine the number of data points of the second data set and divide the unit simulation time into a second preset time interval of the number of data points.

[0134] The third initial parameter acquisition unit is used to control the pressure head model to perform extrusion simulation on the sample model according to the total displacement, and output data according to a second preset time interval during the extrusion simulation to obtain a second displacement set and a second pressure value set of the pressure head model.

[0135] The fourth initial parameter acquisition unit is used to obtain a second stress value set at a preset characteristic position on the sample model based on the JC damage criterion after the extrusion simulation is completed.

[0136] In some optional implementations, the constraint condition determination module 1103 includes:

[0137] The first-layer constraint condition judgment unit is used to obtain a first displacement pressure curve according to the first displacement set and the first pressure value set, and to obtain a second displacement pressure curve according to the second displacement set and the second pressure value set, and to compare the first displacement pressure curve and the second displacement pressure curve to obtain the Euclidean distance.

[0138] The second-layer constraint condition judgment unit is used to judge whether the Euclidean distance is less than a preset distance threshold. If the Euclidean distance is less than the preset distance threshold, the average error of the extrusion experiment and the extrusion simulation is calculated according to the first stress value set and the second stress value set.

[0139] The third-level constraint condition judgment unit is used to judge whether the average error is less than the preset error threshold. If the average error is not less than the preset error threshold, the single error of each preset feature position is calculated and the maximum single error is judged whether it is less than the preset error threshold.

[0140] In some optional implementations, the parameter calibration module 1104 includes:

[0141] A parameter adjustment unit, used to binary encode the value range of the preset parameter according to the preset precision based on the genetic algorithm to obtain a binary coded value set of the preset parameter;

[0142] The first parameter inversion unit is used to adjust the preset parameters based on the binary coded value set if the Euclidean distance is not less than the preset distance threshold, and return to the step of controlling the indenter model to perform extrusion simulation on the sample model based on the JC damage criterion.

[0143] The second parameter inversion unit is used to adjust the preset parameters based on the binary coded value set if the maximum single error is not less than the preset error threshold, and return to the step of controlling the indenter model to perform extrusion simulation on the sample model based on the JC damage criterion.

[0144] The calibration parameter determination unit is used to satisfy the constraint condition if the average error is less than the preset error threshold, and determine the calibration parameter value of the preset parameter according to the adjusted binary code value.

[0145] The further functional description of each of the above modules and units is the same as that of the above corresponding embodiments and will not be repeated here.

[0146] The calibration device of the JC damage parameters in this embodiment is presented in the form of a functional unit, where the unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and memory that executes one or more software or fixed programs, and / or other devices that can provide the above functions.

[0147] The embodiment of the present invention also provides a computer device having the above Fig.11 The calibration device of JC damage parameters is shown.

[0148] See also Fig.12 , Fig.12 is a schematic diagram of the structure of a computer device provided by an optional embodiment of the present invention, such as Fig.12 As shown, the computer device includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. Various components are connected to each other using different buses for communication, and can be installed on a common mainboard or installed in other ways as needed. The processor can process the instructions executed in the computer device, including instructions stored in or on the memory to display the graphical information of the GUI on an external input / output device (such as, a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Similarly, multiple computer devices can be connected, and each device provides some necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Fig.12 A processor 10 is taken as an example.

[0149] The processor 10 may be a central processing unit, a network processor or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be a dedicated integrated circuit, a programmable logic device or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic or any combination thereof.

[0150] The memory 20 stores instructions executable by at least one processor 10, so that the at least one processor 10 executes the method shown in the above embodiment.

[0151] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created according to the use of the computer device, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely arranged relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0152] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid state drive; the memory 20 may also include a combination of the above types of memory.

[0153] The computer device also includes an input device 30 and an output device 40. The processor 10, the memory 20, the input device 30 and the output device 40 may be connected via a bus or other means. Fig.12 The example of connecting through bus is taken in the following.

[0154] The input device 30 can receive input digital or character information, and generate key signal input related to the user settings and function control of the computer device, such as a touch screen, a keypad, a mouse, a track pad, a touch pad, an indicator bar, one or more mouse buttons, a trackball, a joystick, etc. The output device 40 may include a display device, an auxiliary lighting device (e.g., an LED) and a tactile feedback device (e.g., a vibration motor), etc. The above-mentioned display device includes but is not limited to a liquid crystal display, a light emitting diode, a display and a plasma display. In some optional embodiments, the display device can be a touch screen.

[0155] The embodiment of the present invention also provides a computer-readable storage medium. The method according to the embodiment of the present invention can be implemented in hardware, firmware, or can be implemented as a computer code that can be recorded in a storage medium, or can be implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and will be stored in a local storage medium through a network download, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state hard disk, etc.; further, the storage medium can also include a combination of the above types of memories. It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor, or hardware, the method shown in the above embodiment is implemented.

[0156] A part of the present invention may be applied as a computer program product, such as a computer program instruction, which, when executed by a computer, can call or provide the method and / or technical solution according to the present invention through the operation of the computer. Those skilled in the art should understand that the existence of the computer program instruction in a computer-readable medium includes, but is not limited to, a source file, an executable file, an installation package file, etc., and accordingly, the way in which the computer program instruction is executed by the computer includes, but is not limited to: the computer directly executes the instruction, or the computer compiles the instruction and then executes the corresponding compiled program, or the computer reads and executes the instruction, or the computer reads and installs the instruction and then executes the corresponding installed program. Here, the computer-readable medium may be any available computer-readable storage medium or communication medium accessible to the computer.

[0157] The embodiment of the present invention also provides a method for testing the mechanical strength of a battery pack. Figure 1 , Figure 5 or Figure 6 The calibration parameter value determined by the calibration method of the JC damage parameter shown determines the JC damage criterion, and the extrusion condition of the battery pack is simulated based on the JC damage criterion to test the mechanical strength of the battery pack.

[0158] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A method for calibrating JC damage parameters, characterized in that: The method comprises: The step of controlling the pressure head to perform an extrusion experiment on the test sample until the test sample is damaged, obtaining a first displacement set and a first pressure value set of the pressure head during the extrusion process, and a first stress value set of the test sample after the extrusion is completed; Based on the JC damage criterion, preset parameters are set to control the indenter model to perform extrusion simulation on the sample model, and a second displacement set and a second pressure value set of the indenter model during the extrusion simulation process, and a second stress value set of the sample model after the extrusion simulation is completed, wherein the test sample corresponds to the sample model, and the indenter corresponds to the indenter model; a step of determining a constraint condition, determining a constraint condition according to the first displacement set, the first pressure value set, the first stress value set, the second displacement set, the second pressure value set, and the second stress value set; If the constraint condition is not met, the preset parameters of the JC damage criterion are adjusted, and the step of controlling the indenter model to perform extrusion simulation on the sample model based on the JC damage criterion is returned until the constraint condition judgment step is judged to meet the constraint condition, and the calibration parameter value of the preset parameter is obtained.

2. The method according to claim 1, characterized in that The obtaining of the first displacement set and the first pressure value set of the pressure head during the extrusion process, and the first stress value set of the test sample after the extrusion is completed, includes: Acquire a first data set obtained by measuring the pressure head at a first preset time interval during the extrusion process, wherein the first data set includes multiple groups of data points, and the data points include corresponding initial displacements, initial pressure values, and initial times; Taking the data point corresponding to the last pressure value of zero among the multiple initial pressure values ​​as the cutoff point, deleting the data points before and after the cutoff point in the first data set, to obtain a second data set; subtracting the initial displacement corresponding to the cutoff point from the initial displacement in the second data set, and subtracting the initial time corresponding to the cutoff point from the initial time in the second data set, to obtain a third data set; Adding a group of data points containing preset data before the starting position of the third data set to obtain a fourth data set, wherein the fourth data set includes the first pressure value set, the first displacement set and the first time set; A first stress value set is obtained by measuring a preset characteristic position of the test sample after extrusion, wherein there is at least one preset characteristic position.

3. The method according to claim 2, characterized in that The step of setting preset parameters based on the JC damage criterion, controlling the indenter model to perform extrusion simulation on the sample model, and obtaining a second displacement set and a second pressure value set of the indenter model during the extrusion simulation, and a second stress value set of the sample model after the extrusion simulation is completed, includes: Constructing the corresponding sample model and the indenter model according to the structural materials of the test sample and the indenter, wherein the indenter model is closely attached to the sample model; Determining a value range of a preset parameter of a constitutive equation in the JC damage criterion according to the structural material, and determining an initial value of the preset parameter based on the value range; Subtract the initial displacement corresponding to the cutoff point from the last initial displacement in the second data set to obtain the total displacement of the indenter; Determining the number of data points of the second data set, and dividing the unit simulation time into second preset time intervals of the number of data points; Controlling the indenter model to perform extrusion simulation on the sample model according to the total displacement, and outputting data according to the second preset time interval during the extrusion simulation process to obtain a second displacement set and a second pressure value set of the indenter model; Based on the JC damage criterion, a second stress value set of the preset characteristic position on the sample model is obtained after the extrusion simulation is completed.

4. The method according to claim 2, characterized in that: The performing constraint condition judgment according to the first displacement set, the first pressure value set, the first stress value set, the second displacement set, the second pressure value set, and the second stress value set includes: obtaining a first displacement-pressure curve according to the first displacement set and the first pressure value set, obtaining a second displacement-pressure curve according to the second displacement set and the second pressure value set, and comparing the first displacement-pressure curve with the second displacement-pressure curve to obtain a Euclidean distance; Determining whether the Euclidean distance is less than a preset distance threshold, and if the Euclidean distance is less than the preset distance threshold, calculating an average error of an extrusion experiment and an extrusion simulation according to the first stress value set and the second stress value set; Determine whether the average error is less than a preset error threshold; if the average error is not less than the preset error threshold, calculate the single error of each preset feature position and determine whether the maximum single error is less than the preset error threshold.

5. The method according to claim 4, characterized in that If the constraint condition is not met, the preset parameters of the JC damage criterion are adjusted, and the step of controlling the indenter model to perform extrusion simulation on the sample model based on the JC damage criterion is returned until the constraint condition is met to obtain the calibrated parameter value of the preset parameter, including: Based on a genetic algorithm, the value range of the preset parameter is binary-encoded according to a preset precision to obtain a binary-encoded value set of the preset parameter; If the Euclidean distance is not less than the preset distance threshold, the preset parameters are adjusted based on the binary coded value set, and the process returns to the step of controlling the indenter model to perform extrusion simulation on the sample model based on the JC damage criterion; If the maximum single error is not less than the preset error threshold, the preset parameters are adjusted based on the binary coded value set, and the process returns to the step of controlling the indenter model to perform extrusion simulation on the sample model based on the JC damage criterion; If the average error is less than the preset error threshold, the constraint condition is satisfied, and the calibration parameter value of the preset parameter is determined according to the adjusted binary code value.

6. A JC damage parameter calibration device, characterized in that: The device comprises: A first parameter acquisition module, used for controlling the pressing head to perform an extrusion experiment on the test sample until the test sample is damaged, and obtaining a first displacement set and a first pressure value set of the pressing head during the extrusion process, and a first stress value set of the test sample after the extrusion is completed; A second parameter acquisition module is used to set preset parameters based on the JC damage criterion, control the indenter model to perform extrusion simulation on the sample model, and obtain a second displacement set and a second pressure value set of the indenter model during the extrusion simulation, and a second stress value set of the sample model after the extrusion simulation, wherein the test sample corresponds to the sample model, and the indenter corresponds to the indenter model; a constraint condition judgment module, used for the step of constraint condition judgment, performing constraint condition judgment according to the first displacement set, the first pressure value set, the first stress value set, the second displacement set, the second pressure value set and the second stress value set; The parameter calibration module is used to adjust the preset parameters of the JC damage criterion if the constraint condition is not met, and return to the step of controlling the indenter model to perform extrusion simulation on the sample model based on the JC damage criterion, until the constraint condition judgment step is judged to meet the constraint condition, and the calibration parameter value of the preset parameter is obtained.

7. A computer device, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the JC damage parameter calibration method according to any one of claims 1 to 5 by executing the computer instructions.

8. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the JC damage parameter calibration method according to any one of claims 1 to 5.

9. A computer program product, characterized in that The method comprises computer instructions, wherein the computer instructions are used to cause a computer to execute the JC damage parameter calibration method according to any one of claims 1 to 5.

10. A method for testing the mechanical strength of a battery pack, characterized in that: The JC damage criterion is determined according to the calibration parameter value determined by the calibration method for the JC damage parameter according to any one of claims 1 to 5, and the extrusion condition of the battery pack is simulated based on the JC damage criterion to test the mechanical strength of the battery pack.

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