Battery pack modeling method considering different collision forms

Abstract

The invention relates to the technical field of battery pack testing, in particular to a battery pack modeling method considering different collision forms. The method comprises the following steps: establishing a geometric model by using ANSYS modeling software, including establishing a battery pack framework, adding a battery module, and establishing and simplifying a road foreign matter geometry; importing the model into Hypermesh to perform grid division, setting different sizes according to parts and collision positions, and performing division by using hexahedron entity units; lS-prepost is introduced to set structural connection, such as welding, gluing, bolt connection and the like; importing ANSYS to establish a finite element model, and analyzing and calculating, including importing and checking, and setting solver parameters, a contact algorithm, boundary conditions and material attributes; different collision working conditions are set, and impact simulation is carried out; finite element model simulation is carried out on different working conditions, and deformation stress conditions of the battery pack under different collisions are analyzed. According to the technical scheme, the performance and the failure mechanism of the power battery in various collision forms can be accurately reflected.

Description

Technical Field

[0001] This invention relates to the field of battery pack testing technology, and more specifically to a battery pack modeling method that considers different collision types. Background Technology

[0002] In recent years, electric vehicles have become an important direction for the automotive industry due to their zero or low emissions, and their ownership has continued to rise rapidly. However, as the electric vehicle market continues to expand, incidents of new energy vehicles catching fire after collisions have occurred frequently, raising public concern and anxiety about the safety of electric vehicle batteries.

[0003] In the complex operating environment of electric vehicles, collisions are a risk factor that is difficult to completely avoid. When a collision occurs, the power battery pack, as the core energy storage component of an electric vehicle, is generally the first to bear the brunt of the external impact. This impact directly causes deformation of the battery pack casing, which further compresses the internal battery modules and cells. Because battery modules and cells are extremely sensitive to mechanical stress, the integrity of their internal structure will be severely damaged as external mechanical stress continues to act and accumulate. This damage may trigger a series of serious safety accidents, such as internal short circuits in the battery. The electrical sparks generated by the short circuit may ignite flammable materials inside the battery, leading to a fire, or even an explosion in extreme cases, posing a huge threat to the lives and property of passengers.

[0004] However, the collision scenarios encountered by electric vehicles in actual operation are extremely complex and diverse. Collision loads are transient, dynamic, and exhibit large intensity variations, which are fundamentally different from quasi-static loads. Existing research results based on quasi-static loads are insufficient to accurately reflect the complex mechanical responses and failure mechanisms of power batteries under real-world collision scenarios. Currently, existing technologies mainly focus on quasi-static load conditions, deeply exploring the battery components and the failure and short-circuit behavior of individual cells under quasi-static mechanical action, but lack in-depth exploration of the mechanical failure mechanisms of vehicle-based power batteries under different dynamic collision loads. Summary of the Invention

[0005] The purpose of this invention is to propose a battery pack modeling method that considers different collision types, which can accurately reflect the performance and failure mechanism of power batteries under various collision types.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a battery pack modeling method considering different collision modes, comprising: The geometric model was created using ANSYS's built-in Design Modeler modeling software, including creating the basic framework of the battery pack, adding battery modules, creating road debris geometry, and performing geometric simplification. The established geometric model is imported into Hypermesh software for mesh generation. Different mesh sizes are set according to different parts and collision locations, and hexahedral solid elements are used to generate the mesh. Import the model into LS-prepost to set up structural connections, including connection methods such as welding, gluing, and bolting. Import the established geometric model into ANSYS's built-in LS-Dyna to create a finite element model and perform analysis calculations, including model import and checking, setting solver parameters, setting contact algorithms, setting boundary conditions, and defining material properties; Different collision conditions were set up, including the bottom collision condition of the battery pack, the side pillar collision condition of the battery pack, and the side collision condition of the battery pack, and impact simulation was performed. Finite element model simulations were performed for different collision conditions to analyze the deformation and stress of the battery pack under different collision modes.

[0007] Beneficial effects of the basic scheme: When constructing the basic framework of the battery pack, battery modules, and key geometries such as road debris in Design Modeler, the core structural features related to collision are retained. By omitting unnecessary structures and homogenizing the battery, the model is simplified while avoiding interference from invalid details on the simulation results, ensuring that the model can realistically reflect the structural interactions during collision.

[0008] In Hypermesh, different mesh sizes are set for different components and collision locations, and hexahedral solid elements are used for meshing. This ensures the calculation accuracy of the collision area (fine mesh captures local deformation) while controlling the overall computational load, so that the mesh quality meets the requirements of high-precision simulation.

[0009] In LS-prepost, structural connection methods such as welding, gluing, and bolting are accurately defined. In LS-Dyna, contact algorithms are set appropriately to restore the mechanical transmission path between various components of the battery pack and the contact behavior during collisions, ensuring that the transmission of force and deformation conforms to the actual physical process.

[0010] By simplifying geometry (omitting non-critical structures), homogenizing the battery to simplify its internal complex structure, and setting targeted mesh sizes (using coarser meshes in non-collision areas), the number of elements and nodes in the model is significantly reduced while maintaining accuracy. This directly reduces the computational load of LS-Dyna and significantly shortens the computation time for a single simulation.

[0011] From Design Modeler modeling to Hypermesh mesh generation, and then to LS-prepost connection settings and LS-Dyna solution analysis, a standardized process has been formed, which reduces repetitive operations and trial and error costs in the modeling process and accelerates the model building and simulation iteration speed.

[0012] Typical scenarios such as bottom impact, side pole impact, and side impact were set up to simulate various collision risks that the battery pack may encounter during vehicle operation (such as bottom scraping against foreign objects, side impact by poles, etc.), providing data support for a comprehensive assessment of the battery pack's collision safety.

[0013] In-depth analysis of structural response: Through simulation analysis of battery pack deformation and stress under different working conditions, weak links can be accurately located, providing a direct basis for the structural optimization design of the battery pack.

[0014] The established finite element model is based on standardized software processes (ANSYS series, Hypermesh, LS-Dyna, etc.), which facilitates subsequent parameter adjustments and model modifications according to different battery pack models, sizes, or collision conditions, adapting to diverse research needs.

[0015] Simulation results can accurately reflect the actual deformation and stress of the battery pack after a collision, providing a reliable theoretical basis for battery pack design verification, safety performance evaluation, and collision protection scheme formulation, reducing reliance on physical experiments and lowering R&D costs.

[0016] As a feasible and preferred solution, a geometric model of the battery pack is established using the concept of homogenization. The details of the internal microstructure of the battery are ignored, and the internal structure of the battery, such as the electrode, separator, and electrolyte, is regarded as a material structure. The overall mechanical properties of the battery are simulated by adjusting the material parameters.

[0017] As a feasible and preferred approach, the battery pack geometric model is created in the ANSYS built-in Design Modeler, specifically including: Create a floor-type battery pack basic framework, establish a base plate plane, and determine the dimensions based on the actual battery pack parameters; construct the side wall structure, with thickness and height according to design requirements; add internal partition structures, taking into account the actual layout. When adding battery modules, each module is directly connected to the battery pack base plate, and a cuboid geometry is created according to the layout of 8 modules; Create road debris geometry, including cones, cylinders, and cuboids, to simulate bottom collision, side pillar collision, and side collision scenarios. The geometric model is simplified by removing small structures and non-load-bearing components, and omitting details of the BMS system and series battery wiring.

[0018] As a feasible and preferred approach, the established geometric model is imported into Hypermesh software for mesh generation, specifically including the following: The grid size for the battery pack bottom plate and impact area is 10 mm, the grid size for road debris is 40 mm, the grid size for the cover, partition and non-directly impacted areas is 30 mm, the grid size for the outer shell is 40 mm, and the grid size for the lead base plate is 20 mm.

[0019] As a feasible and preferred approach, the model is meshed using hexahedral solid elements during the meshing process, and tetrahedral elements are prohibited except for local transitional use of pentahedral elements.

[0020] As a feasible and preferred solution, the model is imported into LS-prepost for structural connection settings, including connection methods such as welding, gluing, and bolting. Specifically, this includes the following: The steel battery pack casing is fixed by bolts; the internal transverse partitions are fixed to the battery pack bottom plate and the battery pack bottom plate are fixed to the surrounding fixing plates by welding; the battery modules are fixed to the bottom plate by adhesive; the top cover, plastic partition and outer shell inside the battery module are connected by snap-fit.

[0021] As a feasible and preferred solution, different collision conditions are set up, specifically including the following: For the bottom collision scenario of the battery pack, the cone-shaped impact object is set with a cone radius R=15mm, a cone angle β=45°, an impact material weight of 15.00kg, and an impact velocity of 15m / s. For the side collision scenario of the battery pack, the road object is set as a cylinder with a radius R=30cm and a height H=70cm, and an impact velocity of 10m / s. For the side collision scenario of the battery pack, the road object is set as a cuboid with dimensions of 200×20×20cm, and an impact velocity of 10m / s.

[0022] As a feasible and preferred approach, the collision pattern can be altered by changing the geometry of the foreign object and the collision location. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the method flow of the present invention.

[0024] Figure 2 This is a front view schematic diagram of the geometric model of the battery pack of the present invention.

[0025] Figure 3 This is a three-dimensional structural diagram of the battery pack geometric model of the present invention.

[0026] Figure 4 This is a schematic diagram of the finite element model of the battery pack of the present invention.

[0027] Figure 5 This is a schematic diagram of the bottom collision simulation and energy curve of the present invention.

[0028] Figure 6 This is a schematic diagram of the side-pillar collision simulation and energy curve of the present invention.

[0029] Figure 7 This is a schematic diagram of the side-impact simulation and energy curve of the present invention. Detailed Implementation

[0030] To make the technical solution and advantages of this application clearer, the technical solution of the present invention will be further described in detail below with reference to the accompanying drawings. It is understood that the specific embodiments described herein are only some embodiments of the present invention, and are only used to explain this application, not to limit it. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered isolated; they can be combined with each other to achieve better technical effects. The same reference numerals appearing in the accompanying drawings of the following embodiments represent the same features or components, and can be applied to different embodiments.

[0031] Furthermore, unless otherwise defined, the technical or scientific terms used in this invention description shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains.

[0032] The present invention will now be described in further detail with reference to the accompanying drawings: Reference Figure 1 A battery pack modeling method that considers different collision types includes the following steps.

[0033] There are three main types of models in battery mechanics modeling: refined models, homogenized models, and RVE models. This modeling method adopts homogenization. Because this method uses the battery pack as the research object and performs finite element simulation from a macroscopic perspective, it needs to consider time costs based on different impactor geometries and collision locations; therefore, the homogenization approach is adopted for modeling and simulation. Specifically, the internal structure of the battery, including electrodes, separator, and electrolyte, is treated as a single material structure, including the following steps: Ignoring the details of the battery's internal microstructure; The overall mechanical properties of the battery are simulated by adjusting material parameters; The overall behavior of the battery is characterized using equivalent material properties; Simplify the wiring structure of series-connected batteries inside the battery module; The BMS (Battery Management System) in the battery pack is omitted.

[0034] Step S100: Establish a geometric model using ANSYS's built-in Design Modeler software. This simplifies the model and saves computation time by simplifying the wiring structure of the series-connected batteries within the battery module and the BMS system in the battery pack. This includes: Step S101: Create the basic frame of the battery pack, establish the base plate plane, and determine the dimensions according to the actual battery pack parameters; construct the side wall structure, with thickness and height as required by the design; add the internal partition structure, taking into account the actual layout. In this embodiment, the established battery pack is a "Floor" type structure with an overall mass of 443 kg, a rated voltage of 384.8 V, and a rated capacitance of 185 Ah.

[0035] Step S102: Add battery modules, each directly connected to the battery pack base plate. Refer to the battery pack geometry model. Figure 2 and Figure 3 As shown, a cuboid geometry is created according to the layout of 8 modules. The size of each module is set. In this embodiment, the size of each module is set to 815mm×300mm×90mm. The spacing and arrangement of the modules are adjusted.

[0036] Step S103: Create the road debris geometry, including symmetrical cones, cylinders, and cuboids, to simulate the bottom and side impacts of a battery pack. Adjust the geometric parameters according to the actual situation. Create the cone by rotating the section and set the cone angle parameters; create the cylinder by specifying the radius and height parameters; input the length, width, and height dimensions of the ship's cuboid.

[0037] Step S104: Geometric simplification process, removing small structures that do not affect the collision results, simplifying complex geometric features of the connection parts, and optimizing the surface transition area.

[0038] Step S200: Import the established geometric model into Hypermesh software for mesh generation. During numerical simulation, the mesh refinement directly affects computational efficiency and significantly impacts the accuracy of the final analysis; therefore, selecting an appropriate mesh size is crucial.

[0039] In this embodiment, the grid should be refined at the bottom plate of the battery pack and the collision location, with a grid size of 10mm; the size of the road debris should be 40mm; the grid size of the cover, partition, and other battery modules that do not directly bear the impact load should be set to 30mm; the grid size of the battery pack outer shell should be 40mm; and the grid size of the lead base plate should be 20mm.

[0040] The model uses hexahedral solid elements to improve computational efficiency. Pentahedral elements are allowed for transitions in special regions, but tetrahedral elements should be avoided to ensure computational accuracy. In this embodiment, the final mesh element count is 53,118; the number of nodes is 76,790.

[0041] Step S300: Import the model into LS-prepost for structural connection settings. The connection methods used in the model mainly include welding, gluing, and bolting.

[0042] Specifically, the steel battery pack housing (bottom plate and cover plate) is fixed with bolts; the internal transverse partitions are fixed to the battery pack bottom plate, and the battery pack bottom plate is fixed to the surrounding fixing plates by welding; the battery modules are fixed to the bottom plate by adhesive. The top cover, plastic partitions, and outer shell inside the battery modules are connected by snap-fit. Meanwhile, the bolt connections are added using a binding contact method. Binding constraints are created between each partition of the battery pack and the bottom plate, and binding constraints are established between the bottom plate and the cover plate at their edges; other contacts do not require separate settings.

[0043] Step S400: Import the established geometric model into ANSYS's built-in LS-Dyna to create a finite element model and perform analysis and calculations. The battery pack finite element model is referenced... Figure 4 As shown, it includes: Step S401: Model import and inspection, check mesh integrity, verify material property assignment, and confirm boundary condition settings. Step S402: Set the solver parameters, which include the time step, the number of calculation loops, and the termination time. In one embodiment, the initial time step is 0.0001s, the time step safety factor is 0.01, and the number of calculation loops is 10,000,000; the termination time is set according to the collision conditions (usually 0.01 to 0.05s).

[0044] Step S403, setting the contact algorithm, including: Master-slave definition: The impactor is the master surface, and the battery pack is the slave surface; Contact type: Automatic face-to-face contact; Coefficient of friction: 0.2; Contact stiffness: Default value.

[0045] Step S404, Set boundary conditions: Battery pack fixing method: constrain all degrees of freedom at the bottom; Initial conditions for the impacting object: Set the initial velocity.

[0046] Step S500: Based on the homogenization modeling concept, material properties are defined. The internal structures of the battery, such as electrodes, separator, and electrolyte, are treated as a single material structure, and the battery structure is simulated by adjusting material parameters. The remaining components of the battery pack, as well as the base plate and cover plate, are made of common steel. Detailed material parameters are shown in Tables 1 and 2.

[0047] Table 1 Parameters of Structural Steel Shell

[0048] Table 2 Parameters of Aluminum Alloy Steel Shell

[0049] Step S600: Set different collision conditions, including: Step S601: For the battery pack bottom collision scenario, set the cone radius of the conical impactor to R=15mm, the cone angle to β=45°, and the impact material to 15.00kg. Set the impact velocity of the conical impactor to 15m / s.

[0050] Step S602: For the battery pack side pillar collision scenario, the road object is set as a cylinder with a radius R=30cm, a height H=70cm, and an impact velocity of 10m / s.

[0051] Step S603: For the side impact scenario of the battery pack, the road object is set as a cuboid with dimensions of 200×20×20cm and an impact velocity of 10m / s. Impact simulation is then performed after setting up each scenario.

[0052] The collision pattern can be altered by changing the geometry of the foreign object and its collision location.

[0053] Step S700: Perform finite element model simulation for different collision conditions. For calculation control settings, the calculation and analysis time for impact collision problems is generally set to a small time, so this paper selects 0.0001s; the time step safety factor is set to 0.01 by default; the number of calculation loops is set to 10,000,000, and the analysis results are presented.

[0054] In bottom-impact scenarios, the damage mode is significantly influenced by the location of the impact contact point. To ensure accurate assessment of the battery pack's impact condition, impact tests should exclude separators, reinforcing strips, plastic components, and the top cover of the battery module, as these areas have relatively limited effects during impact and cannot simulate the extreme and severe bottom-impact scenarios. Therefore, in this invention, the impact point between the foreign object and the battery pack is chosen to be at the center of the lower left battery module. In side-impact scenarios, Analysis of the stress response contour map shows that the impact result at the bottom of the battery pack is referenced. Figure 5As shown, under bottom impact conditions, the deformation of the battery pack bottom plate and the battery module at the impact location at a certain impact velocity reveals that the maximum deformation of the battery pack bottom plate is generally 4-5 times that of the battery module at the impact location. This indicates that the battery pack can effectively withstand a large portion of the impact energy during bottom impact, protecting the internal battery modules. The side column impact results are shown in the figure. Figure 6 As shown. Under battery side pillar collision conditions, due to the small contact area between the side pillar and the battery pack, the side pillar intrusion collision will result in significant deformation and intrusion. The battery pack side collision results are shown in the figure. Figure 7 As shown, under side impact conditions, the battery pack deforms less due to the large contact area and full contact with the side of the battery pack. The energy curves of the three impacts show that the combined energy changes and energy is basically conserved after the battery pack is impacted.

[0055] In the embodiments of this patent, a three-dimensional finite element model of the battery pack under different collision modes was established. By simulating different types of collisions with the battery pack and observing the model response, the deformation and stress of the battery pack under different operating conditions can be analyzed, providing reference value for the design of electric vehicle battery packs and possessing high engineering value.

[0056] The above content is merely an embodiment of the present invention. Commonly known structures and characteristics of the solutions are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can improve and implement this solution based on the guidance provided in this application and their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A battery pack modeling method considering different collision types, characterized in that, include: The geometric model was created using ANSYS's built-in Design Modeler modeling software, including creating the basic framework of the battery pack, adding battery modules, creating road debris geometry, and performing geometric simplification. The established geometric model is imported into Hypermesh software for mesh generation. Different mesh sizes are set according to different parts and collision locations, and hexahedral solid elements are used to generate the mesh. Import the model into LS-prepost to set up structural connections, including connection methods such as welding, gluing, and bolting. Import the established geometric model into ANSYS's built-in LS-Dyna to create a finite element model and perform analysis calculations, including model import and checking, setting solver parameters, setting contact algorithms, setting boundary conditions, and defining material properties; Different collision conditions were set up, including the bottom collision condition of the battery pack, the side pillar collision condition of the battery pack, and the side collision condition of the battery pack, and impact simulation was performed. Finite element model simulations were performed for different collision conditions to analyze the deformation and stress of the battery pack under different collision modes.

2. The battery pack modeling method considering different collision types according to claim 1, characterized in that, The battery pack geometric model is established using the concept of homogenization. The details of the internal microstructure of the battery are ignored, and the internal structure of the battery, such as the electrode, separator, and electrolyte, is regarded as a material structure. The overall mechanical properties of the battery are simulated by adjusting the material parameters.

3. A battery pack modeling method considering different collision types according to claim 1, characterized in that, Create the battery pack geometric model in ANSYS's built-in Design Modeler, specifically including: Create a floor-type battery pack basic framework, establish a base plate plane, and determine the dimensions based on the actual battery pack parameters; construct the side wall structure, with thickness and height according to design requirements; add internal partition structures, taking into account the actual layout. When adding battery modules, each module is directly connected to the battery pack base plate, and a cuboid geometry is created according to the layout of 8 modules; Create road debris geometry, including cones, cylinders, and cuboids, to simulate bottom collision, side pillar collision, and side collision scenarios. The geometric model is simplified by removing small structures and non-load-bearing components, and omitting details of the BMS system and series battery wiring.

4. The battery pack modeling method considering different collision types according to claim 1, characterized in that, Import the completed geometric model into Hypermesh software for mesh generation, which includes the following: The grid size for the battery pack bottom plate and impact area is 10 mm, the grid size for road debris is 40 mm, the grid size for the cover, partition and non-directly impacted areas is 30 mm, the grid size for the outer shell is 40 mm, and the grid size for the lead base plate is 20 mm.

5. A battery pack modeling method considering different collision types according to claim 4, characterized in that, In the mesh generation step, the model is meshed using hexahedral solid elements. Except for the local transitional use of pentahedral elements, the use of tetrahedral elements is prohibited.

6. The battery pack modeling method considering different collision types according to claim 1, characterized in that, Import the model into LS-prepost to configure structural connections, including welding, adhesive bonding, bolting, and other connection methods. Specifically, this includes the following: The steel battery pack casing is fixed by bolts; the internal transverse partitions are fixed to the battery pack bottom plate and the battery pack bottom plate are fixed to the surrounding fixing plates by welding; the battery modules are fixed to the bottom plate by adhesive; the top cover, plastic partition and outer shell inside the battery module are connected by snap-fit.

7. A battery pack modeling method considering different collision types according to claim 1, characterized in that, Different collision conditions are set, including the following: For the bottom impact scenario of the battery pack, the cone-shaped impactor is set with a cone radius R=15mm, a cone angle β=45°, an impact material weight of 15.00kg, and an impact velocity of 15m / s. For the side impact scenario of the battery pack, the road object is set as a cylinder with a radius R=30cm and a height H=70cm, and an impact velocity of 10m / s. For the side impact scenario of the battery pack, the road object is set as a cuboid with dimensions of 200×20×20cm, and an impact velocity of 10m / s.

8. A battery pack modeling method considering different collision types according to claim 7, characterized in that, The collision pattern can be altered by changing the geometry of the foreign object and its collision location.

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