Battery collision simulation material modeling method

Abstract

The invention discloses a collision simulation material modeling method for a battery. The method comprises the following steps: S1) performing a quasi-static extrusion test on the front surface, the top surface and the side surface of the battery; s2) establishing a battery finite element model and boundary conditions and load conditions of extrusion simulation in three directions; s3) simulating the front extrusion process of the battery, S4) simulating the top surface extrusion process of the battery, and adjusting the collision simulation material parameters of the battery cell in the direction, so that the displacement-extrusion force curves of simulation and test are fitted; s5) simulating the side extrusion process of the battery, and adjusting the collision simulation material parameters of the battery cell in the direction, so that the displacement-extrusion force curves of simulation and test are fitted; s6) checking whether the simulation and test displacement-extrusion force curves of the front extrusion of the battery are still fitted or not, if not, returning to S3), S7) checking whether the simulation and test displacement-extrusion force curves of the top extrusion of the battery are still fitted or not, and if not, returning to S4), and S8) obtaining battery cell collision simulation material parameters of the battery.

Description

Technical Field

[0001] This invention relates to a simulation material modeling method, specifically a collision simulation material modeling method for batteries. Background Technology

[0002] The rapid development of new energy vehicles has placed higher demands on the collision safety of power battery systems. Accurately simulating the mechanical behavior of batteries during collisions is crucial for the structural safety design and risk assessment of battery packs. Currently, mainstream power batteries mainly include long and thin blade batteries (usually with a length-to-height ratio greater than 3:1) and block-shaped square batteries (usually with a length-to-height ratio less than 3:1), both of which exhibit significant mechanical anisotropy in their structure.

[0003] However, current collision simulation material modeling techniques for these two types of batteries face common core challenges:

[0004] 1. Distortion in experimental data acquisition:

[0005] In quasi-static extrusion tests to obtain the intrinsic mechanical properties of battery materials, traditional general-purpose fixture designs have significant shortcomings due to the structural characteristics of the batteries. For blade batteries, out-of-plane buckling or warping deformation easily occurs during extrusion in the thickness direction (Y-axis) and width direction (Z-axis), resulting in the measured displacement-extrusion force curves being mixed with unrealistic bending effects and failing to accurately reflect the material's response under pure compression. For prismatic batteries, similar bending or warping deformation problems arise in side (Y-axis) and bottom (Z-axis) extrusion tests due to insufficient fixation, making the test data unable to truly represent the material's mechanical properties in those directions. Existing fixtures struggle to effectively suppress these instability modes, causing systematic errors in the test data and providing unreliable input for subsequent simulation modeling.

[0006] 2. Insufficient accuracy in simulation modeling:

[0007] At the simulation modeling level, existing methods generally fail to fully characterize the complex three-dimensional anisotropic mechanical behavior of battery materials. Most studies employ isotropic or simplified orthotropic material models, neglecting the strong coupling effect of material parameters in different directions. For example, adjusting material parameters in one direction (such as the Y-axis) may significantly interfere with simulation prediction results in other directions (such as the X-axis or Z-axis). This limitation leads to significant deviations in models calibrated based on experimental data from a single or limited number of directions when predicting complex multi-directional collision loads (such as side impacts, bottom impacts, etc.), resulting in insufficient simulation accuracy and making it difficult to meet the safety design requirements of high-reliability battery systems.

[0008] Therefore, there is an urgent need to develop a battery collision simulation material modeling method that can overcome the above-mentioned defects. This method should be able to ensure the accuracy of data from the source of the experiment and accurately characterize the anisotropy of the material and its coupling effect in the simulation, so as to establish a high-fidelity battery collision simulation model. Summary of the Invention

[0009] Based on the above background, the present invention aims to solve the following problems existing in the prior art:

[0010] Issues with the accuracy of experimental data: Due to the structural characteristics of blade batteries and prismatic batteries, existing extrusion test fixtures cannot effectively suppress unstable deformations such as bending and warping in non-extrusion directions. This results in the obtained displacement-extrusion force curves containing unrealistic mechanical responses, failing to accurately reflect the intrinsic compression behavior of battery materials in a single direction, and making the input data for simulation modeling unreliable.

[0011] Simulation model accuracy issues: Existing collision simulation models generally use isotropic or simplified anisotropic material models, failing to accurately characterize the strong mechanical anisotropy caused by the internal structure of the battery, and neglecting the coupling effects between material parameters in multiple directions. This results in significant deviations between the calibrated model's predictions under complex multi-directional loads and the actual situation, thus limiting the accuracy of battery system collision safety assessments.

[0012] To solve the above-mentioned technical problems, the present invention provides a

[0013] A method for modeling materials in battery collision simulation, comprising the following steps:

[0014] S1) Quasi-static extrusion tests were conducted on the front, top, and side surfaces of the battery to obtain the displacement-extrusion force curves of the battery in each direction.

[0015] S2) Establish the finite element model of the battery, as well as the boundary conditions and load conditions for the extrusion simulation in three directions;

[0016] S3) Simulate the front-side extrusion process of the battery, adjust the collision simulation material parameters of the cell in this direction, and fit the displacement-extrusion force curve of the simulation with that of the experiment.

[0017] S4) Simulate the extrusion process on the top surface of the battery, adjust the collision simulation material parameters in this direction of the cell, and fit the displacement-extrusion force curve of the simulation with that of the experiment;

[0018] S5) Simulate the side extrusion process of the battery and adjust the collision simulation material parameters of the cell in this direction to fit the displacement-extrusion force curve of the simulation with that of the experiment.

[0019] S6) Check if the displacement-compression force curve of the battery front compression simulation and the test still fits. If it no longer fits, return to S3).

[0020] S7) Check if the displacement-extrusion force curve of the battery top surface extrusion is still fitted to the simulation and test. If it is no longer fitted, return to S4.

[0021] S8) obtains the material parameters for the battery cell collision simulation.

[0022] Establish a three-axis coordinate system: the X-axis is perpendicular to the front of the battery, the Y-axis is perpendicular to the top of the battery, and the Z-axis is perpendicular to the side of the battery.

[0023] The extrusion test in S1) uses a special fixture to suppress deformation in the non-extrusion direction: when extruding from the front, the YZ plane on one side of the battery is fixed and a cylindrical indenter is used to extrude along the X-axis; when extruding from the top, first limiting clamps are installed on both sides of the battery; when extruding from the side, second limiting clamps are installed on both sides of the battery.

[0024] The cell collision simulation material parameters described in S3), S4), and S5) include Young's modulus E0, yield strain εy, first / second tangent modulus E1 / E2, tensile yield stress σyield, shear modulus G0, shear yield strain γy, shear tangent modulus G1, and combined stress parameter εc in three directions; S6) checks and adjusts 8 parameters related to the X-axis and combined stress parameter; S7) checks and adjusts 8 parameters related to the Y-axis; and S8) outputs 25 parameters.

[0025] S6) and S7) constitute an iterative verification mechanism, which eliminates the multi-directional parameter coupling effect through closed-loop verification.

[0026] The batteries include blade batteries and prismatic batteries.

[0027] In the finite element model, the battery cell adopts orthogonal anisotropic material to define the material constitutive relation and is modeled using hexahedral bulk elements.

[0028] Mean square error was used as an indicator of the quality of the quantitative simulation and experimental curve fitting.

[0029] The present invention also provides a collision simulation material modeling and simulation device for implementing the method of the battery, comprising:

[0030] The test substrate, and the X-axis extrusion device, the Y-axis extrusion device, the Z-axis extrusion device and the data acquisition system disposed thereon;

[0031] The X-axis, Y-axis, and Z-axis extrusion devices each include a clamp for fixing the corresponding plane of the battery and a cylindrical pressure head that can move along the corresponding axis. The Y-axis and Z-axis extrusion devices also include constraint clamps for constraining the battery.

[0032] The present invention also provides a battery collision simulation material modeling simulation system, wherein the simulation module includes: a finite element analysis module for battery collision, an iterative calibration module, and a simulation parameter output module.

[0033] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0034] 1. High reliability of test data: By using special constraint fixtures (such as concave limiting clamps and auxiliary clamps) designed for the structural characteristics of blade batteries (long and thin type) and square batteries (block type), undesirable deformations such as bending and warping are effectively suppressed in the extrusion test. This allows the obtained displacement-extrusion force curve to truly reflect the intrinsic mechanical response of the battery material in a single direction, providing a reliable data foundation for high-precision simulation modeling.

[0035] 2. High fidelity of simulation model: accurate anisotropic characterization: In the finite element model, the cell adopts an orthogonal anisotropic material model with 25 parameters, which can essentially characterize the different compression, tension and shear mechanical behaviors of battery materials in three orthogonal directions, breaking through the limitations of isotropic or simplified models.

[0036] 3. Elimination of parameter coupling effect: The original "step-by-step fitting and iterative verification" calibration strategy (i.e., first calibrate one direction, then calibrate the next direction, and then backtrack to verify the calibrated direction, and iterate in a loop) systematically solves the coupling optimization problem of mutual interference of material parameters in multiple directions. The final parameter set can simultaneously ensure a high degree of agreement between the simulation and experimental results in three directions, and the model prediction accuracy is greatly improved.

[0037] 4. Strong versatility and practicality: The method and equipment of this invention are uniformly applicable to blade batteries and prismatic batteries with anisotropic characteristics, covering multi-directional impact conditions commonly encountered in new energy vehicle collision simulations, such as frontal, side, and bottom impacts. The established accurate material model can be directly used for battery pack and system-level collision safety simulations, significantly improving the efficiency of safety design and the reliability of risk assessment, and has strong engineering practical value. Attached Figure Description

[0038] Figure 1 First embodiment, square battery model diagram;

[0039] Figure 2 Flowchart of the method of the present invention in the first embodiment;

[0040] Figure 3 The first embodiment involves the experimental setup for extruding a square battery along the X-axis;

[0041] Figure 4 The first embodiment involves the experimental setup for extruding a square battery along the Y-axis.

[0042] Figure 5 The first embodiment involves the experimental setup for extruding a square battery along the Z-axis.

[0043] Figure 6 First embodiment: Finite element model of a square battery;

[0044] Figure 7 First embodiment material constitutive model diagram (compressed);

[0045] Figure 8 First embodiment material constitutive model diagram (tension);

[0046] Figure 9 First embodiment material constitutive model diagram (shear);

[0047] Figure 10 Displacement-compression force curves from X-axis experiments and simulations in the first embodiment;

[0048] Figure 11 Displacement-compression force curves from Y-axis experiments and simulations in the first embodiment;

[0049] Figure 12 Displacement-compression force curves from experiments and simulations in the Z-axis direction of the first embodiment;

[0050] Figure 13 Material parameter diagram of collision simulation in the X-axis direction of the square battery cell in the first embodiment;

[0051] Figure 14 Material parameter diagram of collision simulation in the Y-axis direction of the square battery cell in the first embodiment;

[0052] Figure 15 Material parameter diagram of collision simulation in the Z-axis direction of the square battery cell in the first embodiment;

[0053] Figure 16 Second embodiment blade battery model diagram;

[0054] Figure 17 Flowchart of the method of the present invention in the second embodiment;

[0055] Figure 18 The second embodiment involves the experimental setup for extruding a blade battery along the X-axis.

[0056] Figure 19 The second embodiment involves the experimental setup for extruding a blade battery along the Y-axis.

[0057] Figure 20 The experimental setup for extruding the blade battery in the Z-axis direction in the second embodiment;

[0058] Figure 21 The second embodiment is a finite element model of a blade battery.

[0059] Figure 22 Second embodiment material constitutive model diagram (compressed);

[0060] Figure 23 Second embodiment material constitutive model diagram (tension);

[0061] Figure 24 Second embodiment material constitutive model diagram (shear);

[0062] Figure 25 The displacement-compression force curves from X-axis experiments and simulations in the second embodiment;

[0063] Figure 26 The displacement-compression force curves of the Y-axis direction in the second embodiment;

[0064] Figure 27 The displacement-compression force curves of the Z-axis direction in the second embodiment;

[0065] Figure 28 Material parameter diagram of blade battery cell collision simulation in the second embodiment;

[0066] Figure 29 This is a flowchart of the method of the present invention. Detailed Implementation

[0067] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0068] like Figure 29 As shown, this invention provides a method for modeling materials for battery collision simulation, including the following steps:

[0069] S1) Quasi-static extrusion tests were conducted on the front, top, and side surfaces of the battery to obtain the displacement-extrusion force curves of the battery in each direction.

[0070] S2) Establish the finite element model of the battery, as well as the boundary conditions and load conditions for the extrusion simulation in three directions;

[0071] S3) Simulate the front-side extrusion process of the battery, adjust the collision simulation material parameters of the cell in this direction, and fit the displacement-extrusion force curve of the simulation with that of the experiment.

[0072] S4) Simulate the extrusion process on the top surface of the battery, adjust the collision simulation material parameters in this direction of the cell, and fit the displacement-extrusion force curve of the simulation with that of the experiment;

[0073] S5) Simulate the side extrusion process of the battery and adjust the collision simulation material parameters of the cell in this direction to fit the displacement-extrusion force curve of the simulation with that of the experiment.

[0074] S6) Check if the displacement-compression force curve of the battery front compression simulation and the test still fits. If it no longer fits, return to S3).

[0075] S7) Check if the displacement-extrusion force curve of the battery top surface extrusion is still fitted to the simulation and test. If it is no longer fitted, return to S4.

[0076] S8) obtains the material parameters for the battery cell collision simulation.

[0077] Establish a three-axis coordinate system: the X-axis is perpendicular to the front of the battery, the Y-axis is perpendicular to the top of the battery, and the Z-axis is perpendicular to the side of the battery.

[0078] The extrusion test in S1) uses a special fixture to suppress deformation in the non-extrusion direction: when extruding from the front, the YZ plane on one side of the battery is fixed and a cylindrical indenter is used to extrude along the X-axis; when extruding from the top, first limiting clamps are installed on both sides of the battery; when extruding from the side, second limiting clamps are installed on both sides of the battery.

[0079] The cell collision simulation material parameters described in S3), S4), and S5) include Young's modulus E0, yield strain εy, first / second tangent modulus E1 / E2, tensile yield stress σyield, shear modulus G0, shear yield strain γy, shear tangent modulus G1, and combined stress parameter εc in three directions; S6) checks and adjusts 8 parameters related to the X-axis and combined stress parameter; S7) checks and adjusts 8 parameters related to the Y-axis; and S8) outputs 25 parameters.

[0080] S6) and S7) constitute an iterative verification mechanism, which eliminates the multi-directional parameter coupling effect through closed-loop verification.

[0081] The batteries include blade batteries and prismatic batteries.

[0082] In the finite element model, the battery cell adopts orthogonal anisotropic material to define the material constitutive relation and is modeled using hexahedral bulk elements.

[0083] Mean square error was used as an indicator of the quality of the quantitative simulation and experimental curve fitting.

[0084] The present invention also provides a collision simulation material modeling and simulation device for implementing the method of the battery, comprising:

[0085] The test substrate, and the X-axis extrusion device, the Y-axis extrusion device, the Z-axis extrusion device and the data acquisition system disposed thereon;

[0086] The X-axis, Y-axis, and Z-axis extrusion devices each include a clamp for fixing the corresponding plane of the battery and a cylindrical pressure head that can move along the corresponding axis. The Y-axis and Z-axis extrusion devices also include constraint clamps for constraining the battery.

[0087] The present invention also provides a battery collision simulation material modeling simulation system, wherein the simulation module includes: a finite element analysis module for battery collision, an iterative calibration module, and a simulation parameter output module.

[0088] Figure 1 A square battery model used in the first embodiment of the present invention is shown. This battery has an aspect ratio of approximately 2:1 and a relatively small thickness, exhibiting significant anisotropy. For clarity, orientation is defined as follows: Figure 1 The X, Y, and Z axes are shown. Figure 2 This invention is aimed at Figure 1 The flowchart below shows an embodiment of a collision simulation method for a square battery. Figure 1 Provide a detailed explanation of the specific implementation process for each step.

[0089] The first step is to Figure 1 The square battery shown was subjected to quasi-static extrusion tests along its three mutually orthogonal axes (X, Y, and Z) to obtain displacement-extrusion force curves in each direction. In this embodiment, the diameter of the rigid cylinder was 150 mm, and the extrusion was performed at a quasi-static speed (1 mm / s). The battery fixing method and extrusion equipment configuration used in the test are as follows: Figure 3 , Figure 4 and Figure 5 As shown. For the bottom compression test of the battery, the compression surface is the side that contacts the bottom of the battery system. If the battery is upright (terminal surface facing up), the compression surface is the bottom surface of the battery (the other side of the terminal surface); if the battery is inverted (terminal surface facing down), the compression surface is the top surface of the battery (terminal surface).

[0090] Specifically, Figure 3 A test setup for extruding the front of a square battery along the X-axis is described. In this setup, the YZ plane of one side of the square battery is fixed to a rigid test substrate. The YZ plane of the other side is subjected to extrusion along the X-axis by a rigid cylindrical indenter, wherein the central axis of the rigid cylinder is parallel to the vertical direction of the battery. During the test in this embodiment, the cylindrical indenter applies a displacement load at an extrusion speed of 1 mm / s, and displacement-extrusion force data are recorded simultaneously to obtain the displacement-extrusion force curve of the battery in the X-axis direction. The test process is observed, and extrusion is stopped if the battery experiences a short circuit, leakage, or fire, or if the extrusion force exceeds 100 kN, or if the extrusion deformation reaches 30% of the overall size of the extrusion deformation.

[0091] Figure 4This experiment demonstrates the setup for extruding the side of a square battery along the Y-axis. The battery is placed horizontally, with one XZ plane fixed to a test substrate, while the other XZ plane is subjected to extrusion along the Y-axis by a rigid cylindrical indenter. The central axis of the rigid cylinder is perpendicular to the vertical direction of the battery. To effectively limit potential bending deformation or lateral instability around the X-axis during extrusion, rigid clamps are placed on the upper and lower surfaces of the battery for constraint. The length of the upper and lower clamps is 2 / 3 of the length of the square battery. This length design ensures the stability of the sample while providing deformation space for possible X-axis deformation of the square battery during extrusion. In this embodiment, the cylindrical indenter extrudes the battery along the Y-axis at an extrusion speed of 1 mm / s, and displacement-extrusion force data is recorded simultaneously to obtain the displacement-extrusion force curve along the Y-axis.

[0092] Figure 5 This experiment demonstrates the setup for extruding the bottom surface of a square battery along the Z-axis. The battery is placed horizontally, with one XY plane rigidly fixed to a test substrate. The other XY plane is subjected to extrusion along the Z-axis by a rigid cylindrical indenter, the central axis of which is perpendicular to the horizontal direction of the battery. To ensure that the fixed end of the battery maintains stable contact with the substrate throughout the experiment, preventing warping or slippage, a slender rigid clamp is provided on the side of the battery near the fixed end for auxiliary constraint. The width of the clamp is 20-40 mm. In this embodiment, the cylindrical indenter extrudes the battery along the Z-axis at an extrusion speed of 1 mm / s, and displacement-extrusion force data is recorded simultaneously to obtain a displacement-extrusion force curve along the Z-axis.

[0093] The second step, based on Figure 1 For the actual structure of the square battery shown, a corresponding finite element model should be established. This model needs to accurately reflect the battery's geometric shape and key structural features. For example... Figure 6As shown, the simulation model includes a shell, tabs, and a cell. The shell is modeled using shell elements, while the tabs and cell are modeled using hexahedral solid elements. The outer contour of the cell mesh elements needs to conform to the actual core contour. The battery cell uses orthotropic materials to define its material constitutive relations. For the X, Y, and Z axes of the cell, compressive material parameters (Young's modulus E0, yield strain εy, first tangent modulus E1, second tangent modulus E2), tensile material parameters (Young's modulus E0, tensile yield stress σyield), and shear material parameters (shear modulus G0, shear yield strain γy, shear tangent modulus G1) are defined respectively. Additionally, a combined stress parameter εc is defined separately, acting on the compressive material constitutive model in all directions. The entire cell material parameters include eight material parameters in three directions and one common defined parameter, totaling 25 parameters. These parameters are defined with initial values ​​based on experience. The compressive, tensile, and shear material constitutive models for each direction are shown below. Figure 7-9 As shown. Subsequently, based on the specific conditions of the extrusion tests in the three directions mentioned above (including boundary constraints, indenter type, indenter loading method, and quasi-static loading rate), a completely consistent simulation environment and initial simulation parameters were set in the finite element software.

[0094] The third step involves performing a compression simulation calculation on the front of the battery, based on the finite element model established in the second step. This simulation simulates the compression process along the X-axis. In this simulation, the material model parameters related to the mechanical response in the X-axis direction are adjusted to fit the displacement-compression force curve obtained from the simulation calculation to the curve obtained from the X-axis direction experiment in the first step.

[0095] The key equations for displacement-compression force calculation in the simulation are as follows:

[0096] 1. Total strain (where δ is the displacement of the extruded cylinder, α is the relative slip in the shear direction, and x0 is the total width of the square battery):

[0097] 2. Elastic stage stress:

[0098] 3. Stress during the plastic stage:

[0099] 4. Multiaxial yield condition:

[0100]

[0101] 5. Total force calculation:

[0102] Therefore, in this embodiment, the key material parameters to be adjusted include: Young's modulus E0, yield strain εy, first tangent modulus E1, second tangent modulus E2, tensile yield stress σyield, shear modulus G0, shear yield strain γy, shear tangent modulus G1, and combined stress parameter εc. Specifically, the combined stress parameter εc is determined first. According to the displacement-compression pressure calculation equation, the initial segment of the displacement-compression pressure curve is mainly determined by Young's modulus E0 and yield strain εy, while the middle and later segments are mainly determined by the first tangent modulus E1 and the second tangent modulus E2. Therefore, these four parameters are adjusted. Finally, fine-tuning is achieved by adjusting the shear and tension-related parameters (tensile yield stress σyield, shear modulus G0, shear yield strain γy, and shear tangent modulus G1). By adjusting these parameters, the following can be achieved: Figure 10 The simulated displacement-compression pressure curve along the X-axis is shown as a fit between the simulated displacement-compression pressure curve and the experimental curve.

[0103] Whether the curve fit is satisfactory is evaluated by the following mean squared error (MSE):

[0104] In the formula, n is the number of samples. In this embodiment, the calculation is performed by sampling at a displacement interval of 0.1 mm. y^sim is the simulated value, and y^exp is the experimental value. When the MSE is less than the specified value, the fitting is considered successful.

[0105] The fourth step, based on the parameter set initially determined in the third step, is to complete the extrusion simulation calculation of the battery side, that is, to simulate the extrusion process along the Y-axis. In this simulation, the material model parameters (E0, εy, E1, E2, σyield, G0, γy, G1 in the Y-axis direction) related to the mechanical response in the Y-axis direction are adjusted as described in the third step, so that the displacement-extrusion force curve in the Y-axis direction obtained by the simulation is similar to the curve obtained by the Y-axis direction experiment in the first step. Figure 11 The fit shown.

[0106] Fifth, after completing the Y-axis parameter fitting in step four, it is necessary to check whether the X-axis parameters obtained in step three need to be corrected. This is because parameters related to the Y-axis were introduced in step four, and these parameters may have mutually coupled characteristics, potentially affecting the simulation results in the X-axis direction. Therefore, all currently determined parameters need to be substituted into the model, and the X-axis extrusion simulation needs to be performed again to check whether the simulated X-axis displacement-extrusion pressure curve still maintains a good fit with the experimental curve. If the root mean square error of the fit no longer meets the requirements, it is necessary to return to step three and readjust the relevant parameters in the X-axis direction; if it still meets the requirements, proceed to step six.

[0107] Step 6: Based on the parameter set determined in the previous steps, complete the extrusion simulation calculation of the battery bottom surface, that is, simulate the extrusion process along the Z-axis. In this simulation, the material model parameters (E0, εy, E1, E2, σyield, G0, γy, G1 in the Z-axis direction) related to the mechanical response in the Z-axis direction are adjusted as described in Step 3, so that the displacement-extrusion force curve obtained in the Z-axis direction obtained in Step 1 fits the curve obtained from the Z-axis direction experiment. In this embodiment, through parameter adjustment, the following is ultimately achieved: Figure 12 The fitting of the experimental and simulated displacement-compression force curves in the Z-axis direction is shown.

[0108] Step 7: After completing the Z-axis parameter fitting in Step 6, it is necessary to check again whether the X-axis parameters obtained in Step 3 need to be corrected. This is because Step 6 introduced parameters related to the Z-axis, which may also affect the simulation results in the X-axis direction. Substitute all the currently determined parameters into the model and re-perform the X-axis compression simulation, checking whether the simulated X-axis displacement-compression force curve still fits the experimental curve. If the mean square error of the fit no longer meets the requirements, return to Step 3; if it still meets the requirements, continue to Step 8.

[0109] Step 8: After ensuring a good fit in the X-axis direction, similarly, check whether the Y-axis parameters obtained in step 4 need correction. If the mean square error of the fit no longer meets the requirements, return to step 4 and readjust the relevant parameters in the Y-axis direction; if it still meets the requirements, continue to step 9.

[0110] Step nine: After multiple rounds of iterative adjustments and verifications, a set of material parameters for cell collision simulation was finally obtained that accurately reflects the mechanical response of the square battery in three orthogonal directions (X, Y, and Z axes). This parameter set specifically includes the following parameters for each of the three directions: Young's modulus E0, yield strain εy, first tangent modulus E1, second tangent modulus E2, tensile yield stress σyield, shear modulus G0, shear yield strain γy, shear tangent modulus G1, and combined stress parameter εc, totaling 8 types of parameters * 3 directions + 1 combined parameter = 25 parameters. The final parameter values ​​determined in this embodiment are shown in Table 1.

[0111] Table 1

[0112] Based on the final determined set of material parameters, it is possible to base on Figure 7 , Figure 8 and Figure 9 The constitutive models of the compressed, tensile, and shear materials define the data nodes and generate simulated material parameter diagrams of the battery in the X, Y, and Z axes corresponding to compression, tension, and shear loads, respectively. Figure 13The simulated material parameters of the square battery under compression, tension, and shear in the X-axis direction, obtained in this embodiment, are shown. Figure 14 The simulated material parameters of the square battery under compression, tension, and shear in the Y-axis direction are shown. Figure 15 The simulated material parameters of the square battery under compression, tension, and shear in the Z-axis direction are shown.

[0113] Figure 16 The blade battery model used in the second embodiment is shown. This battery has an aspect ratio of approximately 5:1 and a relatively small thickness, exhibiting significant anisotropy. For clarity, orientation is defined as follows: Figure 16 The X, Y, and Z axes are shown. The X-axis is perpendicular to the front of the blade battery, the Y-axis is perpendicular to the top surface of the blade battery, and the Z-axis is perpendicular to the side surface of the blade battery. Figure 17 This invention is aimed at Figure 16 The diagram shows an overall flowchart of an embodiment of a collision simulation material modeling method for blade batteries. The following will combine... Figure 17 Provide a detailed explanation of the specific implementation process for each step.

[0114] The first step involved conducting extrusion tests and collecting data on the blade battery in three directions to obtain displacement-extrusion force curves in each direction. The experimental design fully considered the structural characteristics of the blade battery and employed a specialized testing apparatus to ensure the accuracy of the tests.

[0115] Specifically, Figure 18 This is a test setup for pressing the front side of a blade battery along the X-axis. In this setup, the YZ plane of one side of the blade battery is fixed to a rigid test substrate. The YZ plane of the other side is pressed by a rigid cylindrical indenter along the X-axis, wherein the central axis of the rigid cylinder is parallel to the vertical direction of the battery. Figure 19 The experimental setup for compressing the top surface of a blade battery along the Y-axis is demonstrated. The battery is placed horizontally, with one XZ plane fixed to a test substrate, and the other XZ plane subjected to compression along the Y-axis by a rigid cylindrical indenter, the central axis of which is perpendicular to the vertical direction of the battery. Due to the large aspect ratio of the blade battery, it is prone to buckling during compression; therefore, rigid concave limiting clamps are placed on the left and right sides of the blade battery for constraint. The concave limiting clamps only fix the sides of the blade battery, while preserving the deformation space for deformation in the X-axis direction. Figure 20The experimental setup for compressing the side of a blade battery along the Z-axis is demonstrated. The battery is placed horizontally, with one XY plane rigidly fixed to the test substrate, while the other XY plane is compressed along the Z-axis by a rigid cylindrical indenter, the central axis of which is perpendicular to the horizontal direction of the battery. Due to the large aspect ratio of the blade battery, rigid concave limiting clamps are also provided on the top and bottom sides for constraint. Similarly, the concave limiting clamps only fix the side of the blade battery, while preserving deformation space for deformation in the X-axis direction.

[0116] Based on the aforementioned testing equipment, extrusion tests were conducted on the blade battery in three directions: X, Y, and Z. In the X and Z axis extrusion tests, the extrusion device was a rigid cylinder with a diameter of 150 mm; in the Y axis extrusion test, the extrusion device was a rigid cylinder with a diameter equal to half the battery height. During extrusion, the indenter perpendicularly extruded the blade battery at a speed of 1 mm / s. The displacement-extrusion force curve was synchronously recorded using a high-precision sensor during the extrusion process. The extrusion was stopped if the battery experienced a short circuit, leakage, or fire; if the extrusion force exceeded 100 kN; or if the extrusion deformation reached 30% (X and Z axis extrusion) or 15% (Y axis extrusion) of the overall extrusion deformation.

[0117] The second step is to establish a simulation model of the blade battery based on the experimental setup. In this embodiment, this includes modeling the blade battery, pressure head, substrate, limiting clamp, etc., and applying constraints and displacement velocities.

[0118] The third step involves establishing the finite element model from the second step. This model must accurately reflect the battery's geometry and key structural features. For example... Figure 21 As shown, the simulation model includes a shell, tabs, and a cell. The shell is modeled using shell elements, while the tabs and cell are modeled using hexahedral solid elements. The outer contour of the cell mesh elements needs to conform to the actual core contour. The battery cell uses orthotropic materials to define its material constitutive relations. For the X, Y, and Z axes of the cell, compressive material parameters (Young's modulus E0, yield strain εy, first tangent modulus E1, second tangent modulus E2), tensile material parameters (Young's modulus E0, tensile yield stress σyield), and shear material parameters (shear modulus G0, shear yield strain γy, shear tangent modulus G1) are defined respectively. Additionally, a combined stress parameter εc is defined separately, acting on the compressive material constitutive model in all directions. The entire cell material parameters include eight material parameters in three directions and one common defined parameter, totaling 25 parameters. These parameters are defined with initial values ​​based on experience. The compressive, tensile, and shear material constitutive models for each direction are shown below. Figure 22-24As shown. Next, a simulation of the extrusion process of the blade battery along the X-axis was conducted. During this simulation, the material model parameters related to the mechanical response along the X-axis were adjusted so that the displacement-extrusion force curve obtained from the simulation matched the curve obtained from the first step of the X-axis experiment.

[0119] The key equations for displacement-compression force calculation in the simulation are as follows:

[0120] 1. Total strain (where δ is the displacement of the extruded cylinder, α is the relative slip in the shear direction, and x0 is the total width of the blade battery):

[0121] 2. Constitutive relation of the elastic stage:

[0122] 3. Constitutive relations in the plastic stage:

[0123] 4. Multiaxial yield criterion:

[0124] 5. Shear stress constitutive relation:

[0125] 6. Macroscopic load calculation:

[0126] Therefore, in this embodiment, the adjusted material parameters include: Young's modulus E0, yield strain εy, first tangent modulus E1, second tangent modulus E2, tensile yield stress σyield, shear modulus G0, shear yield strain γy, shear tangent modulus G1, and combined stress parameter εc. Specifically, the combined stress parameter εc is determined first. According to the displacement-compression pressure calculation equation, the initial segment of the displacement-compression pressure curve is mainly determined by Young's modulus E0 and yield strain εy, while the middle and later segments are mainly determined by the first tangent modulus E1 and the second tangent modulus E2. Therefore, these four parameters are adjusted. Finally, fine-tuning is achieved by adjusting the shear and tension-related parameters (tensile yield stress σyield, shear modulus G0, shear yield strain γy, and shear tangent modulus G1). By adjusting these parameters, the desired result is achieved. Figure 25 The simulated displacement-compression pressure curve along the X-axis is shown as a fit between the simulated displacement-compression pressure curve and the experimental curve.

[0127] Mean Squared Error (MSE) is used as an indicator of the quality of fitting quantitative simulation and experimental curves.

[0128] In the formula, n is the number of samples. In this embodiment, one sample is taken for every 0.1 mm displacement. y^sim is the simulated value, and y^exp is the experimental value. When the MSE is less than the specified value, the fitting is considered successful, and the next step can be performed.

[0129] The fourth step involves simulating the extrusion process of the blade battery along the Y-axis, based on the parameter set determined in the third step. During this process, the simulation parameters along the X-axis remain unchanged, while the cell collision simulation material parameters (E0, εy, E1, E2, σyield, G0, γy, G1 in the Y-axis direction) related to the mechanical response are adjusted as described in the third step, so that the simulated displacement-extrusion force curve along the Y-axis closely matches the experimentally obtained curve. Figure 26 The fit shown.

[0130] The fifth step involves simulating the extrusion process of the blade battery along the Z-axis, based on the parameter set determined in the previous steps. During this process, the simulation parameters for the X and Y axes remain unchanged. The cell collision simulation material parameters (E0, εy, E1, E2, σyield, G0, γy, G1 in the Z-axis direction) related to the mechanical response in the Z-axis direction are adjusted as described in the third step, so that the simulated displacement-extrusion force curve in the Z-axis direction closely matches the curve obtained from experiments. Figure 27 The fit shown.

[0131] Step 6: After completing the Z-axis parameter fitting in Step 5, backtrack to verify whether the simulated and experimental X-axis displacement-compression pressure curves still fit well. This is because Steps 4 and 5 introduced parameters related to the Y and Z axes, which may affect the simulation results in the X-axis direction. Therefore, all currently determined parameters need to be substituted into the model, and the X-axis compression simulation needs to be run again to check whether the simulated X-axis displacement-compression pressure curve still maintains a good fit with the experimental curve. If the fitting effect is poor, return to Step 3; if the fitting effect meets the requirements, continue to Step 7.

[0132] Step 7: After ensuring a good fit between the displacement-pressure curve in the X-axis direction, similarly, check whether the Y-axis parameters obtained in step 4 need correction. If the fitting effect does not meet the requirements, return to step 4; if the fitting effect still meets the requirements, continue to step 8.

[0133] Step 8: After multiple rounds of iterative adjustments and verifications, a set of material parameters for cell collision simulation was finally obtained, which accurately reflects the mechanical response of the blade battery in three orthogonal directions (X, Y, and Z axes). This parameter set specifically includes the following parameters for each of the three directions: Young's modulus E0, yield strain εy, first tangent modulus E1, second tangent modulus E2, tensile yield stress σyield, shear modulus G0, shear yield strain γy, shear tangent modulus G1, and combined stress parameter εc, totaling 8 types of parameters * 3 directions + 1 combined parameter = 25 parameters. The final parameter values ​​determined in this embodiment are shown in Table 1.

[0134] Table 1

[0135] Based on the finalized parameter set, according to Figure 22-24 The constitutive models of the material under compression, tension, and shear shown are used to generate the equivalent material parameters of the battery in the X, Y, and Z axes corresponding to compression, tension, and shear loads, respectively. Figure 28 This paper presents the equivalent material parameter diagrams of the blade battery under compression, tension, and shear in the X, Y, and Z axes, which are obtained in this embodiment, providing a complete material model for blade collision simulation.

[0136] The embodiments described above are merely further illustrations of the present invention and are not intended to limit the present invention in any other way. The present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding modifications and changes based on the present invention, but all such modifications and changes should fall within the protection scope of the present invention.

Claims

1. A method of modeling a crash simulation material of a battery, the method comprising: The method comprises the steps of: S1) performing a quasi-static extrusion test on the front, top and side surfaces of the battery to obtain displacement-extrusion force curves of the battery in each direction; S2) establishing a finite element model of the battery and boundary conditions and load conditions for the extrusion simulation in three directions; S3) simulating the front surface extrusion process of the battery, adjusting the material parameters of the battery in the direction of the collision simulation, and fitting the displacement-extrusion force curves of the simulation and the test; S4) simulating the top surface extrusion process of the battery, adjusting the material parameters of the battery in the direction of the collision simulation, and fitting the displacement-extrusion force curves of the simulation and the test; S5) simulating the side surface extrusion process of the battery, adjusting the material parameters of the battery in the direction of the collision simulation, and fitting the displacement-extrusion force curves of the simulation and the test; S6) checking whether the displacement-extrusion force curves of the simulation and the test of the front surface extrusion of the battery still fit, and returning to S3) if they do not fit; S7) checking whether the displacement-extrusion force curves of the simulation and the test of the top surface extrusion of the battery still fit, and returning to S4) if they do not fit; S8) obtaining the material parameters of the battery in the direction of the collision simulation.

2. The method of claim 1, wherein, A three-axis coordinate system is established, with the X-axis being perpendicular to the front surface of the battery, the Y-axis being perpendicular to the top surface of the battery, and the Z-axis being perpendicular to the side surface of the battery.

3. The method of claim 2, wherein, The extrusion test in S1) uses a special fixture to suppress deformation in non-extrusion directions: when extruding the front surface, the YZ plane of one side of the battery is fixed, and a cylindrical indenter is used to extrude along the X-axis; when extruding the top surface, first limiting clamps are installed on both sides of the battery; when extruding the side surface, second limiting clamps are installed on both sides of the battery.

4. The method of claim 1, wherein, The cell impact simulation material parameters of S3), S4) and S5) include Young's modulus E0, yield strain ε y , first / second tangent modulus E1 / E2, tensile yield stress σ yield , shear modulus G0, shear yield strain γ y , shear tangent modulus G1 and combined stress parameter ε c ; S6) checks and adjusts 8 parameters related to X-axis and the combined stress parameter, S7) checks and adjusts 8 parameters related to Y-axis, and S8) outputs 25 parameters.

5. The method of claim 1, wherein, S6) and S7) constitute an iterative verification mechanism to eliminate the coupling effect of multi-directional parameters through closed-loop verification.

6. The method of claim 1, wherein, The battery includes a blade battery and a square battery.

7. The method of claim 1, wherein, In the finite element model, the battery cell is defined as an orthotropic material to define the material constitutive relation, and a hexahedral element is used for modeling.

8. The method of claim 1, wherein, The mean square error is used as an index to quantify the quality of the simulation and test curve fitting.

9. A battery crash simulation material modeling simulation apparatus for implementing the method of any one of claims 1-8, characterized by, It comprises: a test substrate, and X-axis, Y-axis and Z-axis direction extrusion devices and a data acquisition system arranged thereon; wherein the X-axis, Y-axis and Z-axis direction extrusion devices each comprise a fixture for fixing the corresponding plane of the battery, a cylindrical indenter movable along the corresponding axis, and the Y-axis and Z-axis direction extrusion devices further comprise a restraining clamp for restraining the battery.

10. A crash simulation material modeling simulation module for a battery for performing the method of any one of claims 1-8, characterized by, It comprises: a finite element analysis module for battery collision, an iterative calibration module and a simulation parameter output module.

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