A simulation method and device for a bottom ball impact working condition of a power battery

Abstract

The application relates to the technical field of power batteries, in particular to a simulation method and device for a power battery bottom ball impact working condition. Step one, a simplified finite element model of a bottom guard plate and an impact head is established, the material of the bottom guard plate is defined, boundary load conditions are applied, and the maximum reaction force is extracted; step two, a statics analysis model is established and boundary load conditions are applied; step three, the statics is solved to calculate the finite element model, and the result is analyzed and judged. The application combines finite element dynamics and statics simulation analysis methods, greatly reduces the problem of large calculation result dispersion caused by the subjective judgment of engineers, unifies the judgment standard, reduces the test verification rounds, reduces the development cycle, improves the simulation efficiency, solves the problem of poor precision caused by the large size of the dynamics grid and the problem of lacking boundary load in statics.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power batteries, in particular to a simulation method and device for a power battery bottom ball impact working condition. BACKGROUND

[0002] As the power source of pure electric vehicles, power batteries are an important component. When the vehicle is misused or has poor passability, obstacles will inevitably impact the power battery at the bottom, and in severe cases, the power battery will be punctured, thereby causing problems such as fire and explosion. The power battery bottom ball impact test is an effective means to verify the resistance of the power battery to bottom impact. One of the test methods specifies the shape, mass, size, impact direction, and impact energy of the impact head and other related information.

[0003] This test method only provides impact energy and does not provide effective impact load information. If dynamics is used for finite element analysis, the model size is large, and the grid size cannot effectively reflect the accurate stress information of the structure. If statics finite element analysis is used, the effective direct load boundary conditions for statics analysis are lacking.

[0004] Therefore, it is urgent to provide a dynamics and statics combined simulation method for the power battery bottom ball impact working condition to solve the above problems. SUMMARY

[0005] The present application provides a simulation method and device for a power battery bottom ball impact working condition, which combines finite element dynamics and statics simulation analysis methods, greatly reduces the problem of large calculation result dispersion caused by engineer's subjective judgment, unifies the discrimination standard, reduces the test verification rounds, reduces the development cycle, improves the simulation efficiency, solves the problem of poor accuracy caused by large dynamics grid size, and solves the problem of lacking boundary load in statics.

[0006] The technical solution of the present application is described below in combination with the drawings:

[0007] In a first aspect, the embodiments of the present application provide a simulation method for a power battery bottom ball impact working condition, comprising:

[0008] Step one, establish a simplified finite element model of the bottom guard plate 1 and the impact head 2, define the material of the bottom guard plate 1, apply boundary load conditions, and extract the maximum reaction force;

[0009] Step two, establish a statics analysis model and apply boundary load conditions;

[0010] Step three, statically solve the finite element model and analyze and discriminate the results.

[0011] Further, the specific method of step one is as follows:

[0012] 11) Establish a simplified finite element model of the bottom guard plate 1 and the impact head 2; wherein the bottom guard plate 1 is established by shell elements, and the impact head 2 is simulated by a rigid surface;

[0013] 12) Set a contact relationship between the bottom guard plate 1 and the impact head 2;

[0014] 13) Define the materials of the finite element model; define the elastic modulus and Poisson's ratio of the bottom guard plate 1, and define the elastoplastic properties, i.e. the stress-strain curve, of the bottom guard plate material;

[0015] 14) Apply boundary load conditions; calculate the initial speed of the impact head according to the test requirements, and apply it to the reference point position of the simplified rigid surface according to the action direction, and constrain the simplified bottom guard plate 1 around;

[0016] 15) Extract the maximum reaction force; solve by displaying dynamics to extract the relationship curve between the reaction force of the constraint point 4 and time, so as to extract the maximum reaction force.

[0017] Further, in the step 11), the size of the simplified bottom guard plate 1 is cut according to the real fixed boundary, is determined according to the positions of the cross beam fixed point and the frame fixed point, and is simplified as a flat plate; the thickness of the simplified bottom guard plate 1 is the thickness of the real bottom guard plate, and is calculated according to the following formula:

[0018] b = K1·K2·b0

[0019] In the formula, b is the thickness of the simplified bottom guard plate; b0 is the thickness of the real bottom guard plate; K1 is an other structure thickness influence parameter, which is taken as 1.2-1.5; K2 is a structure shape influence parameter, which is taken as 1.0-1.2 according to the shape of the action area;

[0020] In the step 12), the contact relationship is set as limited slip, surface-surface contact, and the initial position adjustment is not set or the setting parameter is below 0.001;

[0021] In the step 13), the elastoplastic properties, i.e. the stress-strain curve, of the bottom guard plate material is obtained by the actual tensile test;

[0022] In the step 14), the initial speed of the impact head 2 is calculated according to the following formula:

[0023]

[0024] In the formula, E k is the test energy; m is the mass of the impact head; v is the initial speed of the impact head;

[0025] The four sides of the simplified bottom guard plate 1 are bound to the 1 free node position by RBE2 rigid unit 3, and all degrees of freedom are constrained;

[0026] In the step 15), the dynamics is calculated by display analysis, ELEMENT BY ELEMENT mode, and the total calculation time is not less than 0.1S;

[0027] The relationship curve of the constraint point ball striking direction support reaction force and time is extracted, and the maximum support reaction force F N .

[0028] Further, the specific method of the step two is as follows:

[0029] 21) A detailed finite element model of the power battery and the impact head 2 is established; wherein the finite element model is established after the impact area at the bottom of the power battery is finely divided;

[0030] 22) Assembly is performed according to the actual assembly relationship; wherein the bottom guard plate and the liquid cooling plate are set in contact;

[0031] 23) The material of the finite element model is defined; the elastic modulus and Poisson's ratio of the material of the finite element model of each component of the power battery are defined; at the same time, the elastic-plastic property of the bottom guard plate 1, the liquid cooling plate, and the cell monomer shell 6 is defined, and the compression property of the cell bottom heat conduction structure adhesive 7 is defined;

[0032] 24) Load boundary conditions are applied; all direction degrees of freedom of the power battery pack clamp fixed point are constrained, and the other degrees of freedom of the impact head reference point except the battery pack height direction are constrained; the maximum reaction force obtained by the dynamics analysis is corrected as the concentrated load of the impact head 2, and is applied to the impact head reference point according to the ball striking direction.

[0033] Further, in the step 21), the structure of the bottom guard plate 1 and the liquid cooling plate in the impact head action area is refined, the refined area is about 5 times the diameter of the impact head area, the grid size of the refined area is not greater than 2mm, and is the same as the grid size of the rigid surface of the simulated impact head;

[0034] The cell monomer adopts an aluminum shell and an internal equivalent structure for simulation, wherein the aluminum shell is simulated by using a real material and thickness, and the internal equivalent structure is simulated by using a soft material with an elastic modulus less than 100MPa;

[0035] In the step 22), the impact head 2 and the bottom guard plate 1, the bottom guard plate and the liquid cooling plate lower plate 5-2, and the liquid cooling plate lower plate 5-2 and the liquid cooling plate upper plate 5-1 are all set as limited slip, face-to-face contact, and the initial geometric adjustment is set as 0 or less than 0.001. Among them, the contact surface area of the bottom guard plate 1 and the liquid cooling plate is the total refined unit area, that is, more than 5 times the area of the impact head 2;

[0036] In the step 23), the bottom guard plate 1, the liquid cooling plate and the cell monomer shell 6 are set according to the elastic-plastic properties of the measured materials;

[0037] The cell bottom structure glue is simplified as an isotropic elastic material simulation, and the elastic modulus E and Poisson's ratio μ are measured according to the uniaxial compression test;

[0038] In the step 24), the maximum reaction force F N is corrected according to the following formula;

[0039] F′ N = K S ·F N

[0040] In the formula, F N is the maximum reaction force extracted by dynamics; K S is a correction coefficient, about 0.5-0.7; F′ N is the corrected maximum reaction force.

[0041] Further, the specific method of the step three is as follows:

[0042] 31) Statics solution calculation finite element model: Newton method is used for nonlinear statics solution, and the stress and strain of each structure are calculated;

[0043] 32) Extracting the equivalent plastic strain and deformation of the bottom guard plate 1, the liquid cooling plate and the cell monomer shell 6 structure;

[0044] 33) According to the mechanical properties of each component material, the damage risk and the invasion amount of each structure to the cell are judged, and the two are analyzed and judged.

[0045] Further, in the step 31), the statics solution opens the geometric nonlinearity; the statics output includes stress, strain, equivalent plastic strain, deformation and contact pressure;

[0046] The discrimination index of the step 33) is as follows:

[0047] Index 1: According to the size relationship between the equivalent plastic strain ε PEEQ and the material fracture elongation A0, whether the component is damaged is judged, and if the following formula is met, the component structure strength safety is determined;

[0048] ε PEEQ <K S ·A0

[0049] In the formula, ε PEEQ is the equivalent plastic strain; A0 is the fracture elongation of the material, K S is the safety factor, 1.0-1.2;

[0050] Index 2: the deformation amount of the power battery cell bottom shell in the height direction cannot exceed 5% of the overall height of the cell, and the cell intrusion amount is determined to be safe;

[0051] The cell shell is determined to be safe when it meets both index 1 and index 2.

[0052] In a second aspect, the embodiment of the present application further provides a simulation device for a power battery bottom ball impact working condition, comprising:

[0053] A first model establishing module is configured to establish a simplified finite element model of the bottom guard plate and the impact head, define the material of the bottom guard plate, apply a boundary load condition, and extract the maximum reaction force.

[0054] A second model establishing module is configured to establish a statics analysis model and apply a boundary load condition.

[0055] An analysis and discrimination module is configured to perform statics solving calculation on the finite element model and analyze and discriminate the results.

[0056] In a third aspect, the embodiment of the present application further provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to realize the simulation method for the power battery bottom ball impact working condition according to any of the embodiments of the present application.

[0057] In a fourth aspect, the embodiment of the present application further provides a computer readable storage medium having a computer program stored thereon, wherein the program is executable on a processor to realize the simulation method for the power battery bottom ball impact working condition according to any of the embodiments of the present application.

[0058] The present application has the following advantages:

[0059] 1) The present application makes full use of the advantages of short calculation period and accurate prediction of finite element analysis, and can timely check the stress, deformation, etc. of the bottom ball impact working condition after the design is completed, and perform targeted optimization design, thereby reducing the test verification rounds and reducing the development period.

[0060] 2) The present application provides a standardized and process-oriented dynamic and statics combined simulation method for the power battery bottom ball impact working condition, which greatly reduces the problem of large calculation result dispersion caused by subjective judgment of engineers from the full-dimensional standardized finite element operation process of finite element modeling, assembly, calculation, evaluation, etc., unifies the discrimination standard, and improves the simulation efficiency.

[0061] 3) The application provides a dynamic and static combined simulation method for a power battery bottom ball impact working condition, which effectively solves the problem of poor precision caused by large dynamic grid size and the problem of lack of boundary load in statics by combining finite element dynamic and static simulation analysis methods. BRIEF DESCRIPTION OF DRAWINGS

[0062] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some of the embodiments of the application, and therefore should not be considered as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0063] Figure 1 A flow chart of the simulation method for a power battery bottom ball impact working condition according to the application;

[0064] Figure 2 A schematic diagram of a simplified dynamic analysis model;

[0065] Figure 3 A schematic diagram of a detailed static analysis model;

[0066] Figure 4 A structure schematic diagram of the simulation device for a power battery bottom ball impact working condition according to the application;

[0067] Figure 5 A structure schematic diagram of an electronic device according to the application. DETAILED DESCRIPTION

[0068] The application will be further described in detail below in combination with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the application, and not to limit the application. In addition, it should be noted that, for the convenience of description, only the parts related to the application are shown in the drawings, not all the structures.

[0069] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. At the same time, in the description of the application, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0070] Embodiment one

[0071] Figure 1A flow chart of a simulation method of a power battery bottom ball impact working condition provided by the embodiment one of the present application, the embodiment can be applicable to the simulation of the power battery bottom ball impact working condition, the method can be executed by a simulation device of the power battery bottom ball impact working condition in the embodiment of the present application, the device can be realized in the form of software and / or hardware, and the method specifically includes the following steps:

[0072] The embodiment of the present application provides a simulation method of a power battery bottom ball impact working condition, which comprises the following steps:

[0073] Step one, a simplified finite element model of the bottom guard plate 1 and the impact head 2 is established, the material of the bottom guard plate 1 is defined, the boundary load condition is applied, and the maximum reaction force is extracted;

[0074] The specific method is as follows:

[0075] 11) A simplified finite element model of the bottom guard plate 1 and the impact head 2 is established for dynamic analysis; wherein the bottom guard plate 1 is established by using a shell element, and the impact head 2 is simulated by using a rigid surface;

[0076] The size of the simplified bottom guard plate 1 is cut according to the real fixed boundary, is determined according to the fixed point positions of the cross beam and the frame, and can be simplified as a flat plate; the thickness of the simplified bottom guard plate 1 adopts the thickness of the real bottom guard plate 1 and is calculated according to the following formula:

[0077] b=K1·K2·b0

[0078] In the formula, b is the thickness of the simplified bottom guard plate; b0 is the thickness of the real bottom guard plate; K1 is an other structure thickness influence parameter, and is 1.2-1.5; K2 is a structure shape influence parameter, and is 1.0-1.2 according to the shape of the action area;

[0079] 12) The contact relationship between the bottom guard plate 1 and the impact head 2 is set;

[0080] The contact relationship is set as limited sliding, surface-surface contact, and the initial position adjustment is not set or the setting parameter is below 0.001;

[0081] 13) The material of the finite element model is defined; the elastic modulus E and the Poisson's ratio μ of the bottom guard plate 1 are defined, and the elastic-plastic property of the bottom guard plate material, i.e. the stress-strain curve, is defined;

[0082] The elastic-plastic property of the bottom guard plate material, i.e. the stress-strain curve, is obtained through the tensile test;

[0083] 14) The boundary load condition is applied; the initial speed of the impact head 2 is calculated according to the test requirement, is applied to the reference point position of the simplified rigid surface according to the action direction, and the simplified bottom guard plate 1 is constrained around; the established dynamic analysis model is as shown in Figure 2as shown.

[0084] In the step 14), the initial speed of the impact head 2 is calculated according to the following formula:

[0085]

[0086] wherein E k is the test energy; m is the mass of the impact head; and v is the initial speed of the impact head.

[0087] The four sides of the simplified bottom guard plate 1 are bound to a 1-degree-of-freedom node position by using RBE2 rigid elements 3, and all degrees of freedom are constrained.

[0088] 15) Extract the maximum reaction force; solve the relationship curve between the reaction force of the constraint point 4 and time by displaying dynamics, so as to extract the maximum reaction force.

[0089] The dynamics is calculated by using the ELEMENT BY ELEMENT mode, and the total calculation time is not less than 0.1S;

[0090] The relationship curve between the support reaction force of the ball hitting direction of the constraint point 4 and time is extracted, and the maximum support reaction force F N .

[0091] Step two, establish a statics analysis model and apply boundary load conditions;

[0092] The specific method is as follows:

[0093] 21) Establish a detailed finite element model of the power battery and the impact head 2 for statics analysis, as shown in Figure 3 It should be noted that the impact area at the bottom of the power battery needs to be divided in detail. The structure of the non-impact area and the structure that does not affect the overall stiffness can be omitted.

[0094] The structure of the bottom guard plate 1 and the liquid cooling plate in the impact head area is refined, the refined area has a diameter of about 5 times the impact head area, the grid size of the refined area is not greater than 2mm, and the grid size is the same as that of the rigid surface of the simulated impact head;

[0095] The cell monomer is simulated by using an aluminum shell and an internal equivalent structure, wherein the aluminum shell is simulated by using a real material and thickness, and the internal equivalent structure is simulated by using a soft material with an elastic modulus less than 100MPa;

[0096] 22) Assemble according to the actual assembly relationship; it should be noted that although the bottom guard plate 1 and the liquid cooling plate (the bottom ball hitting area) may not be in contact in the original state, contact needs to be set to simulate the contact force transmission after the ball hitting, so as to avoid structure penetration;

[0097] The impact head 2 is arranged in limited sliding and face-to-face contact with the bottom guard plate 1, the bottom guard plate 1 is arranged in limited sliding and face-to-face contact with the liquid cooling plate lower plate 5-2, and the liquid cooling plate lower plate 5-2 is arranged in limited sliding and face-to-face contact with the liquid cooling plate upper plate 5-1, and the initial geometric adjustment is 0 or less than 0.001. Among them, the contact surface area of the bottom guard plate 1 and the liquid cooling plate is the total refined unit area, that is, more than 5 times the area of the impact head 2;

[0098] 23) Define the material of the finite element model; define the elastic modulus E and Poisson's ratio μ of the finite element model material of each part of the power battery; at the same time, define the elastic-plastic properties of the bottom guard plate 1, the liquid cooling plate, and the cell monomer shell 6, and define the compression properties of the cell bottom heat-conducting structural adhesive 7;

[0099] The bottom guard plate 1, the liquid cooling plate, and the cell monomer shell 6 are all set according to the elastic-plastic properties of the measured materials;

[0100] The cell bottom structural adhesive is simplified as an isotropic elastic material simulation, and the elastic modulus E and Poisson's ratio μ are measured according to the uniaxial compression test;

[0101] 24) Apply load boundary conditions; constrain the power battery pack clamp fixed point in all directions; constrain the reference point of the impact head 2 in other degrees of freedom except the battery pack height direction; correct the maximum reaction force obtained by dynamic analysis to the concentrated load of the impact head 2, and apply it to the impact head reference point according to the ball hitting direction.

[0102] The maximum reaction force F N obtained by dynamic analysis is corrected according to the following formula;

[0103] F′ N = K S ·F N

[0104] In the formula, F N is the maximum reaction force extracted by dynamics; K S is the correction coefficient, which is about 0.5-0.7; F′ N is the corrected maximum reaction force.

[0105] Step three, statics solving calculation of the finite element model and analysis and judgment of the results.

[0106] The specific method is as follows:

[0107] 31) Statics solving calculation of the finite element model: Newton method is used for nonlinear statics solving, and the stress and strain of each structure are calculated;

[0108] The geometric nonlinearity is turned on for statics solving; the statics output includes stress, strain, equivalent plastic strain, deformation, and contact pressure;

[0109] 32) Extract the equivalent plastic strain and deformation of the bottom protection plate 1, liquid cooling plate, and cell monomer shell 6 structure;

[0110] 33) According to the mechanical properties of each component material, the damage risk of each structure and the invasion amount to the cell are distinguished, and the two are analyzed and distinguished.

[0111] The distinguishing index is as follows:

[0112] Index 1: According to the size relationship of equivalent plastic strain ε PEEQ and material fracture elongation A0, whether the component is damaged is distinguished, and if the following formula is met, the safety of the component structure strength is determined;

[0113] ε PEEQ <K S ·A0

[0114] In the formula, ε PEEQ is the equivalent plastic strain; A0 is the fracture elongation of the material, K S is a safety factor, which is 1.0-1.2;

[0115] Index 2: The deformation amount of the power battery cell bottom shell in the height direction cannot exceed 5% of the overall height of the cell, and the safety of the cell invasion amount is determined;

[0116] The cell shell meets index 1 and index 2 at the same time and is determined to be safe.

[0117] Example two

[0118] Figure 4 A structure schematic diagram of a simulation device for a power battery bottom ball impact working condition provided by the second embodiment of the present application. This embodiment can be applicable to the simulation of the power battery bottom ball impact working condition, and the device can be realized in software and / or hardware. The device can be integrated in any device that provides the function of simulating the power battery bottom ball impact working condition, including:

[0119] A first model establishing module for establishing a simplified finite element model of the bottom protection plate and the impact head, defining the material of the bottom protection plate, applying boundary load conditions, and extracting the maximum reaction force;

[0120] A second model establishing module for establishing a statics analysis model and applying boundary load conditions;

[0121] An analysis and discrimination module for statics solving calculation of the finite element model and analysis and discrimination of the results.

[0122] The above product can execute the method provided by any embodiment of the present application, has the corresponding function module and beneficial effects of executing the method.

[0123] Example three

[0124] Figure 5 This is a schematic diagram of the structure of a computer device according to Embodiment 3 of the present invention. Figure 5 A block diagram of an exemplary computer device 12 suitable for implementing embodiments of the present invention is shown. Figure 5 The computer device 12 shown is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments of the present invention.

[0125] like Figure 5 As shown, the computer device 12 is represented in the form of a general-purpose computing device. The components of the computer device 12 may include, but are not limited to: one or more processors or processing units 16, system memory 28, and a bus 18 connecting different system components (including system memory 28 and processing unit 16).

[0126] Bus 18 represents one or more of several bus architectures, including a memory bus or memory controller, a peripheral bus, a graphics acceleration port, a processor, or a local bus using any of the various bus architectures. For example, these architectures include, but are not limited to, the Industry Standard Architecture (ISA) bus, the Micro Channel Architecture (MAC) bus, the Enhanced ISA bus, the Video Electronics Standards Association (VESA) local bus, and the Peripheral Component Interconnect (PCI) bus.

[0127] Computer device 12 typically includes a variety of computer system readable media. These media can be any available media that can be accessed by computer device 12, including volatile and non-volatile media, removable and non-removable media.

[0128] System memory 28 may include computer system readable media in the form of volatile memory, such as random access memory (RAM) 30 and / or cache memory 32. Computer device 12 may further include other removable / non-removable, volatile / non-volatile computer system storage media. By way of example only, storage system 34 may be used to read and write non-removable, non-volatile magnetic media (…). Figure 5 Not shown; usually referred to as a "hard drive"). Although Figure 5 Not shown, a disk drive for reading and writing to a removable non-volatile disk (e.g., a "floppy disk") and an optical disk drive for reading and writing to a removable non-volatile optical disk (e.g., a CD-ROM, DVD-ROM, or other optical media) may be provided. In these cases, each drive may be connected to bus 18 via one or more data media interfaces. Memory 28 may include at least one program product having a set (e.g., at least one) of program modules configured to perform the functions of the embodiments of the present invention.

[0129] Program / utility 40 having a set of program modules 42 can be stored in memory 28, for example, including an operating system, one or more application programs, other program modules, and program data, each or some combination thereof, which may

[0130] Computer device 12 can also communicate with one or more external devices 14 such as a keyboard or pointing device, a display 24, etc.; one or more devices that enable a user to interact with computer device 12; and / or one or more devices that enable computer device 12 to communicate with one or more other computing devices. Such communication can occur via input / output (I / O) interfaces 22. Still yet, computer device 12 in some embodiments can also include a display 24 that is not physically present, but rather is embedded in a mirror, such that the display surface of display 24 is visually integrated with the mirror surface when the display surface of display 24 is not in use. Additionally, computer device 12 can communicate with one or more networks (such as a local area network (LAN), a wide area network (WAN), and / or the Internet) via network adapter 20. As illustrated, network adapter 20 communicates with the other components of computer device 12 via bus 18. It should be appreciated that although not shown, other hardware and / or software modules could be used in conjunction with computer device 12. Examples, include, but are not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data archival storage systems, etc.

[0131] Processing unit 16 can execute a program stored in system memory 28 to perform various functions and data processing, such as implementing a simulation method of a bottom ball impact condition of a power battery according to embodiments of the present application.

[0132] Embodiment four

[0133] Embodiment four of the present application provides a computer readable storage medium, having stored thereon a computer program, which when executed by a processor, implements a simulation method of a bottom ball impact condition of a power battery according to all embodiments of the present application.

[0134] Any combination of one or more computer readable medium can be utilized. The computer readable medium can be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium can be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium can be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

[0135] A computer readable signal medium can include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal can take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium can be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.

[0136] Program code embodied on a computer readable medium can be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

[0137] Computer program code for carrying out operations of the present application can be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider). In an embodiment, the present application is directed to computer program products comprising machine-readable media for carrying or having machine-executable instructions or programs

[0138] Note that the above merely describes preferred embodiments of the present application and the principles of the technology applied. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and that various obvious changes, modifications and substitutions can be made to the present application without departing from the scope of the present application. Therefore, although the present application has been described in detail through the above embodiments, the present application is not limited to the above embodiments, and can include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the claims.

Claims

1. A method for simulating a bottom ball impact condition of a power battery, characterized in that, The method comprises the following steps: Step one, establishing a simplified finite element model of the bottom guard plate (1) and the impact head (2), defining the material of the bottom guard plate (1), applying boundary load conditions, and extracting the maximum reaction force; Step two, establishing a statics analysis model and applying boundary load conditions; Step three, solving the finite element model by statics and analyzing and judging the results; The specific method of step one is as follows: 11) Establish a simplified finite element model of the bottom guard plate (1) and the impact head (2); wherein the bottom guard plate (1) is established by shell elements, and the impact head (2) is simulated by a rigid surface; 12) Set the contact relationship between the bottom guard plate (1) and the impact head (2); 13) Define the material of the finite element model; define the elastic modulus and Poisson's ratio of the bottom guard plate (1), and define the elastic-plastic properties of the bottom guard plate material, i.e. the stress-strain curve; 14) Apply boundary load conditions; calculate the initial speed of the impact head (2) according to the test requirements, and apply it to the reference point position of the simplified rigid surface according to the action direction, and constrain the simplified bottom guard plate (1) around; 15) Extract the maximum reaction force; extract the relationship curve between the reaction force of the constraint point (4) and the time by solving by display dynamics, so as to extract the maximum reaction force; In step 11), the size of the simplified bottom guard plate (1) is cut according to the real fixed boundary, is determined according to the fixed point positions of the cross beams and the frame, and can be simplified as a flat plate; the thickness of the simplified bottom guard plate (1) is the thickness of the real bottom guard plate, and is calculated according to the following formula: b = K1·K2·b0 In the formula, b is the thickness of the simplified bottom guard plate; b0 is the thickness of the real bottom guard plate; K1 is an other structure thickness influence parameter, which is 1.2-1.5; K2 is a structure shape influence parameter, which is 1.0-1.2 according to the shape of the action area; In step 12), the contact relationship is set as limited slip, surface-surface contact, and the initial position adjustment is not set or the parameter is set below 0.001; In step 13), the elastic-plastic properties of the bottom guard plate material, i.e. the stress-strain curve, are obtained by actual tensile test; In step 14), the initial speed of the impact head (2) is calculated according to the following formula: where E is the test energy; m is the test impactor mass; and v is the initial impactor velocity. k where E is the test energy; m is the test impactor mass; and v is the initial impactor velocity. The four around of the simplified bottom guard plate (1) are bound to the 1 free node position by RBE2 rigid elements (3), and all degrees of freedom are constrained; In step 15), the dynamics is calculated by display analysis, ELEMENT BY ELEMENT mode, and the total calculation time is not less than 0.1S; The relationship curve between the ball hitting direction support reaction force of the constraint point (4) and time is extracted, and the maximum support reaction force F is obtained N ; The specific method of step two is as follows: 21) Establish a detailed finite element model of the power battery and the impact head; wherein the impact area of the bottom of the power battery is divided in detail to establish the finite element model; 22) Assemble according to the actual assembly relationship; wherein the bottom guard plate (1) and the liquid cooling plate are set as a contact relationship; 23) Define the material of the finite element model; define the elastic modulus and Poisson's ratio of the material of the finite element model of each component of the power battery; at the same time, define the elastic-plastic properties of the bottom guard plate (1), the liquid cooling plate and the cell monomer shell (6), and define the compression properties of the cell bottom heat conduction structure adhesive (7); 24) Apply load boundary conditions; constrain the power battery pack clamp fixture fixed point in all directions, constrain the impact head (2) reference point in all directions except the battery pack height direction; modify the maximum reaction force obtained by dynamic analysis to the concentrated load of the impact head (2), and apply it to the reference point of the impact head (2) according to the ball hitting direction; In the step 21), the bottom guard plate (1) of the impact head (2) action area and the structure of the liquid cooling plate are refined, the refined area diameter is about 5 times the diameter of the impact head area, the grid size of the refined area is not greater than 2mm, and the grid size is the same as the grid size of the rigid surface of the simulated impact head (2); The cell monomer adopts aluminum shell and internal equivalent structure for simulation, wherein the aluminum shell is simulated by using real material and thickness, and the internal equivalent structure is simulated by using soft material with elastic modulus less than 100MPa; In the step 22), the impact head (1) and the bottom guard plate (2), the bottom guard plate (2) and the liquid cooling plate lower plate (5-2), and the liquid cooling plate lower plate (5-2) and the liquid cooling plate upper plate (5-1) are all set as limited sliding, face-to-face contact, and initial geometric adjustment is set as 0 or less than 0.001; wherein the contact surface area of the bottom guard plate (1) and the liquid cooling plate is the total refined unit area, that is, more than 5 times the area of the impact head; In the step 23), the bottom guard plate (1), the liquid cooling plate, and the cell monomer shell (6) are all set according to the elastic-plastic properties of the actually measured material; The cell bottom structure glue is simplified as an isotropic elastic material simulation, and the elastic modulus E and Poisson's ratio μ are measured according to the uniaxial compression test; In said step 24) the maximum counterforce F N The correction is made according to the following formula; F' N = K S • F N In the formula, F N is the maximum reaction force extracted from dynamics; K S is a correction coefficient, and is about 0.5-0.7; F' N is the maximum reaction force after correction The specific method of the step three is as follows: 31) Statics solving calculation finite element model: using Newton method for nonlinear statics solving, calculating the stress and strain of each structure; 32) Extracting the equivalent plastic strain and deformation of the bottom guard plate (1), the liquid cooling plate, and the cell monomer shell (6) structure; 33) According to the material mechanical properties of each component, the damage risk and the invasion amount of each structure to the cell are judged, and the two are analyzed and judged in combination; In the step 31), the statics solving opens the geometric nonlinearity; the statics output includes stress, strain, equivalent plastic strain, deformation and contact pressure; The judgment index of the step 33) is as follows: Index 1: According to the equivalent plastic strain ε PEEQ And the size relationship of material fracture elongation A0 discriminates whether the component is damaged, if it meets the requirements of the following formula, the component structure strength is safe; ε PEEQ <K S ·A0 In the formula, ε PEEQ is the equivalent plastic strain; A0 is the elongation at break of the material, K S is the safety factor, taken as 1.0-1.2; Index 2: The deformation of the power battery cell bottom shell in the height direction cannot exceed 5% of the overall height of the cell, and the cell invasion amount is safe; The cell shell is judged to be safe when it meets index 1 and index 2 at the same time.

2. The method of claim 1, wherein, A simulation device for a power battery bottom ball impact working condition is realized, comprising: A first model establishing module is used to establish a simplified finite element model of the bottom guard plate and the impact head, define the material of the bottom guard plate, apply boundary load conditions, and extract the maximum reaction force; A second model establishing module is used to establish a statics analysis model and apply boundary load conditions; An analysis and judgment module is used to statically solve the finite element model and analyze and judge the results.

3. A computer device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor executes the program to realize the simulation method for the power battery bottom ball impact working condition according to claim 1.

4. A computer-readable storage medium having stored thereon a computer program, characterized in that, The program is executed by the processor to implement the simulation method of the bottom ball impact working condition of the power battery as claimed in claim 1.

Images