CN116595823A - Method, device, equipment and medium for detecting mechanical property of power battery - Google Patents
Method, device, equipment and medium for detecting mechanical property of power battery Download PDFInfo
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Abstract
The invention relates to the technical field of battery manufacturing, and discloses a method, a device, equipment and a medium for detecting mechanical properties of a power battery, wherein the method comprises the following steps: constructing an assembly model of the battery pack for finite element analysis, dividing parts of the assembly model into a battery assembly and an anti-vibration assembly, and installing the anti-vibration assembly outside the battery assembly; acquiring attribute parameters of the assembly model, wherein the attribute parameters comprise material parameters and section attribute parameters; defining a reduction parameter for superunit reduction, and calculating a dynamic stiffness matrix reduced to an external interface of the battery assembly through the reduction parameter and the attribute parameter, wherein the dynamic stiffness matrix is used as a superunit for representing the battery assembly; introducing the dynamic stiffness matrix into an anti-vibration component, and solving the mechanical property result of the assembly model; and replacing the anti-vibration component in the assembly model, and returning to the step of introducing the dynamic stiffness matrix into the anti-vibration component to solve the mechanical performance result of the assembly model. The invention improves the mechanical property detection efficiency of the power battery.
Description
Technical Field
The invention relates to the field of battery manufacturing, in particular to a method, a device, equipment and a medium for detecting mechanical properties of a power battery.
Background
With the rapid development of new energy vehicles, the safety of the vehicles is put at the beginning, and the safety of power batteries in the vehicles is important. In general, when a new energy vehicle runs, vibration is continuously generated, resonance occurs if the generated vibration reaches the natural frequency of the power battery, and risks such as cracking, firing, explosion and the like of the power battery may occur, so that it is necessary to know designed mechanical performance parameters such as vibration frequency, stress parameters, strain parameters and the like of the power battery before the power battery is produced. If the mechanical properties of the power cell are too poor, it may be necessary to readjust it. The related technology adopts a finite element analysis method to analyze the mechanical property of the structure, and is not exceptional in the field of batteries, but the finite element analysis method has large calculation amount, and the battery structure is often required to be repeatedly adjusted in practical application, so that the algorithm has excessively long running time and low design efficiency.
The superunit algorithm is a method capable of improving finite element analysis efficiency, which converts a scattered part structure into a whole to generate a superunit to represent some mechanical parameters, the whole model does not need to be solved during each analysis, the generated superunit can be directly used, various industries develop superunit algorithms of the superunit algorithm, the algorithms for calculating the superunit in different fields are generally different, for example, patent document CN113127970A provides a whole vehicle NVH calculation method based on a frequency function superunit, and the analysis efficiency of noise, vibration and vibration roughness is improved by converting a TB model of the whole vehicle into the frequency function superunit, but the algorithm is not directly applicable to a power battery, and a detection method capable of improving the mechanical performance detection efficiency of the power battery is to be developed.
Disclosure of Invention
In view of the above, the invention provides a method, a device, equipment and a medium for detecting the mechanical property of a power battery, so as to solve the problem of low detection efficiency of the mechanical property of the power battery.
In a first aspect, the present invention provides a method for detecting mechanical properties of a power battery, where the method includes: constructing an assembly model of the battery pack for finite element analysis, dividing parts of the assembly model into a battery assembly and an anti-vibration assembly, and installing the anti-vibration assembly outside the battery assembly; acquiring attribute parameters of the assembly model, wherein the attribute parameters comprise material parameters and section attribute parameters; defining a reduction parameter for superunit reduction, and calculating a dynamic stiffness matrix reduced to an external interface of the battery assembly through the reduction parameter and the attribute parameter, wherein the dynamic stiffness matrix is used as a superunit for representing the battery assembly; introducing the dynamic stiffness matrix into an anti-vibration component, and solving the mechanical property result of the assembly model; and replacing the anti-vibration component in the assembly model, and returning to the step of introducing the dynamic stiffness matrix into the anti-vibration component to solve the mechanical performance result of the assembly model.
Defining a finite element assembly model of the power battery, determining an exchangeable anti-vibration component and an irreplaceable battery component, determining attribute parameters and reduction parameters of the model, reducing the battery component based on a dynamic matrix algorithm, and calculating a dynamic stiffness matrix reduced to an external interface of the battery component so as to represent a superunit of the external interface stiffness of the battery component; then introducing the dynamic stiffness matrix into an anti-vibration component, and integrally solving the mechanical performance results such as the natural frequency, stress, strain and the like of the assembly model; aiming at the problem of high structural adjustment difficulty of the battery module in an actual application scene, the embodiment can output a plurality of structural design schemes only by developing vibration-resistant components with various shapes and different materials as replaceable parts, and can detect mechanical properties of various battery structural design schemes in a short time by replacing the vibration-resistant components and repeatedly calculating mechanical property results by utilizing the reduced dynamic stiffness matrix, thereby remarkably improving the mechanical property detection efficiency of the power battery and reducing the model design workload of structural design engineers. Meanwhile, the super unit reduced to the external interface of the battery assembly is calculated based on a dynamic stiffness matrix algorithm, so that a new thought is provided for the mechanical property detection work of the power battery.
In an alternative embodiment, constructing an assembly model of a battery pack includes: constructing a battery tray, a liquid cooling plate, a plurality of battery modules and a bottom guard plate, wherein the liquid cooling plate is arranged above the battery modules, the bottom guard plate is arranged below the battery modules, the battery modules are uniformly arranged between the liquid cooling plate and the bottom guard plate, and the battery tray is arranged below the battery assembly; wherein, liquid cooling board, battery module and end backplate constitute battery pack, and the battery tray constitutes anti vibration subassembly.
Aiming at the structural design of the battery pack, the embodiment provides a battery pack structure comprising a battery tray, a liquid cooling plate, a plurality of battery modules and a bottom guard plate, wherein the structure formed by the liquid cooling plate, the battery modules and the bottom guard plate is used as a battery assembly, and the battery tray is used as an anti-vibration assembly. Aiming at the problem of high structural adjustment difficulty of the battery module in the actual application scene, the embodiment can only take the battery trays with different shapes and materials as the replaceable parts by developing the battery trays, so that the design schemes of the various trays and the superunit composition of the reduced battery module can be respectively and integrally analyzed in a short time, the structural design scheme with the best mechanical property performance is adopted, the mechanical property detection efficiency is improved, and meanwhile, the model design workload of structural design engineers is reduced.
In an alternative embodiment, defining a reduction parameter for superunit reduction, and calculating a dynamic stiffness matrix reduced to an external interface of the battery assembly by the reduction parameter and the attribute parameter, comprising: defining a vibration frequency solving range, a frequency sweep solving range and a reduction method parameter of a dynamic stiffness matrix, wherein the vibration frequency solving range and the frequency sweep solving range are used for determining the connecting force of a connecting point, and the connecting point is a connecting point between a battery assembly and an anti-vibration assembly; defining boundary constraint conditions according to the connection points to obtain the degree of freedom of the connection points; defining control parameters for executing a reduction method in a solving process; generating a motion equation representing the relation among the degree of freedom of the connection point, the connection force of the connection point and the dynamic stiffness matrix through the control parameters; and calling a vibration frequency solving range, a sweep frequency solving range, a reduction method parameter, the degree of freedom of the connecting point and an attribute parameter through the control parameter, and solving a dynamic matrix of the motion equation to obtain a dynamic stiffness matrix.
The method comprises the steps of generating a dynamic matrix at each loading frequency, and then dynamically synthesizing, so that first, defining a reduction parameter for generating a superunit reduction model, wherein the reduction parameter comprises a vibration frequency solving range, a sweep frequency solving range, a reduction method parameter and a degree of freedom of a connecting point, the vibration frequency solving range and the sweep frequency solving range are used for taking values of the loading frequency, so that the connecting force of the connecting point between a battery assembly and an anti-vibration assembly is determined, the degree of freedom of the connecting point is determined by the actual connection installation relation between the battery assembly and the anti-vibration assembly, and then, defining a control parameter for calling the parameter and executing program operation; after preparation work of parameter definition is completed, a reduction method is executed, a motion equation is generated to represent the relation among the degree of freedom of the connection point, the connection force of the connection point and the dynamic stiffness matrix, so that the stiffness matrix of various complex part structures in the battery assembly is reduced to the degree of freedom of the connection point of the battery assembly, then the dynamic matrix is solved based on the defined parameters substituted into the motion equation, the dynamic stiffness matrix capable of representing superunits of the battery assembly is obtained, a new thought is provided for simplifying the battery pack, and the efficiency of mechanical property detection of the battery pack is improved.
In an alternative embodiment, generating an equation of motion representing a relationship between the degrees of freedom of the connection points, the connection forces of the connection points, and the dynamic stiffness matrix by controlling the parameters includes:
creating a kinetic equation for a superunit as
Wherein K is ii (s) dynamic stiffness submatrices, K, representing complex numbers of degrees of freedom within superunits io (s) and K oi (s) dynamic stiffness submatrices representing complex numbers of degrees of freedom of coupling between the interior of the superunit and the connection points, K oo (s) dynamic stiffness submatrices representing complex numbers of degrees of freedom of connection points, u i Represents the degree of freedom in the superunit, u o Representing the degree of freedom of the connection point, f o (s) represents a connection force of the connection points, s represents a superunit;
decomposing the above formula to obtain
K ii (s)u i (s)+K io (s)u o (s)＝0
K oi (s)u i (s)+K oo (s)u o (s)＝f o (s)
The two formulas are combined and converted to obtain
(K oo (s)-K oi (s)K ii (s) -1 K io (s))u o (s)＝f o (s)
Reducing the generation of equations of motion to
In the middle ofRepresenting a dynamic stiffness matrix reduced to the external interface of the battery assembly,/->
In the embodiment, after a corresponding motion equation is created by combining the connection characteristics of the battery assembly and the anti-vibration assembly, the motion equation is simplified and reduced through equation transformation, and a dynamic stiffness matrix only related to the external interface of the battery assembly is generatedFinally, solving the matrix can map the battery assembly into superunits capable of representing mechanical parameters, thereby providing a new idea for simplifying the battery and rapidly detecting the mechanical properties of the battery.
In an alternative embodiment, a dynamic stiffness matrix is introduced into the anti-vibration assembly and the assembly mold is solvedMechanical property results of the type comprising: generating a superunit model based on the dynamic stiffness matrix; assembling the superunit model and the anti-vibration component into an integral model through a connecting point; under the boundary condition of the connection point, reestablishing a new mass matrix and a new stiffness matrix of the whole model according to the dynamic stiffness matrix and the mass matrix of the superunit model, wherein the mass matrix of the superunit model is determined by attribute parameters; by the formulaAnd calculating the vibration frequency of the integral model, wherein f represents the vibration frequency of the integral model, belongs to the mechanical property result of the assembly model, K represents a new stiffness matrix, and M represents a new mass matrix.
According to the embodiment, firstly, a superunit model capable of visualizing the battery assembly is generated based on a dynamic stiffness matrix, then the superunit model and the anti-vibration assembly are assembled according to the connection relation of connection points to form an integral model, one half of the integral model is the superunit model, and the other half of the integral model is the finite element model. The rigidity and the mass of the finite element model can be calculated, under the boundary condition of a preset connection point, according to the assembly relation of the two models in space, the new mass matrix and the new stiffness matrix of the whole model can be recalculated according to the dynamic stiffness matrix of the superunit model and the mass matrix of the superunit model, and finally, the new mass matrix and the new stiffness matrix of the whole model are calculated through formulas And the vibration frequency of the integral model is calculated, so that the integral natural frequency of the battery pack can be obtained, and compared with a finite element analysis method, the analysis efficiency can be remarkably improved.
In an alternative embodiment, the method for solving the mechanical property result of the assembly model further includes:
calculating the deformation of the integral model according to the external force by the following method
{δ} e ＝[K] -1 {F}
In { delta } e The displacement matrix is a displacement matrix of the connection point, represents the deformation of the whole model, F is external force, and K is a new stiffness matrix;
solving the strain of the integral model according to the displacement matrix of the connecting points by
{ε}＝[B]{δ} e
Wherein B is a geometric matrix, { epsilon } represents strain and belongs to the mechanical property result of the assembly model;
calculating stress of the whole model by
{σ s }＝[E]{ε}
In sigma s And the stress is represented, the mechanical property result belongs to an assembly model, and E is the elastic modulus of the battery pack.
In this embodiment, by combining the vibration frequency of the integral model determined in the above embodiment, the strain and stress of the model can be further deduced through external force excitation, so that more mechanical performance parameters are applicable, and the application range of the mechanical performance detection method of the power battery provided by the embodiment of the invention is enlarged.
In an alternative embodiment, the vibration frequency solving range is 0 Hz-300 Hz, the sweep frequency solving range is 0 Hz-200 Hz, the freedom degree of the connecting points comprises 6 space directions, and each connecting point in the battery assembly is connected by adopting a linear display unit.
In this embodiment, considering that one application scenario of this embodiment is a vehicle battery pack, in order to ensure the safety and reliability of the structural design in the vehicle scenario, when creating the superunit through the dynamic matrix algorithm, it is necessary to calculate the random vibration stress within 200Hz so as to make the created superunit more accurate, so that the mode characteristic of the concerned frequency range needs to be set 1.5-2.0 times and the function of each connection point within 200Hz needs to be output, so that this embodiment is optimal in setting the vibration frequency solving range 0 Hz-300 Hz and the sweep frequency solving range 0 Hz-200 Hz. For battery tray, liquid cooling board, a plurality of battery module and the actual structure of backplate at the bottom, the battery pack that backplate, liquid cooling board and a plurality of battery module constitute is detachable connection with battery tray generally, and this embodiment defines 6 space degrees of freedom for the tie point that every generates, and the 6 directions of displacement can be produced to every tie point of characterization have improved the flexibility of establishing superunit. In addition, in the embodiment, each connection point in the battery assembly is connected by using a linear display unit, and because the superunit generated by the battery assembly is a parameter model, the calculated vibration frequency cannot be directly displayed, so that in order to facilitate checking and analyzing a calculation result, the embodiment adopts the linear display unit to establish a contour for the superunit.
In a second aspect, the present invention provides a device for detecting mechanical properties of a power battery, the device comprising: the finite element model construction module is used for constructing an assembly model of the battery pack for finite element analysis, dividing parts of the assembly model into a battery assembly and an anti-vibration assembly, and the anti-vibration assembly is arranged outside the battery assembly; the parameter acquisition module is used for acquiring attribute parameters of the assembly model, wherein the attribute parameters comprise material parameters and section attribute parameters; the superunit calculation module is used for defining a reduction parameter for superunit reduction, and calculating a dynamic stiffness matrix reduced to the external interface of the battery assembly through the reduction parameter and the attribute parameter, wherein the dynamic stiffness matrix is used as a superunit for representing the battery assembly; the performance detection module is used for introducing the dynamic stiffness matrix into the anti-vibration component and solving the mechanical performance result of the assembly model; the iteration detection module is used for replacing the anti-vibration component in the assembly model and returning to the step of introducing the dynamic stiffness matrix into the anti-vibration component to solve the mechanical property result of the assembly model.
In a third aspect, the present invention provides a computer device comprising: the processor executes the computer instructions, thereby executing the method for detecting the mechanical performance of the power battery according to the first aspect or any one of the corresponding embodiments.
In a fourth aspect, the present invention provides a computer readable storage medium, on which computer instructions are stored, the computer instructions being configured to cause a computer to perform a method for detecting mechanical properties of a power battery according to the first aspect or any one of the embodiments corresponding to the first aspect.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic flow chart of a method for detecting mechanical properties of a power battery according to an embodiment of the invention;
fig. 2 is a schematic structural view of a three-dimensional model of a battery pack according to an embodiment of the present invention;
fig. 3 is a schematic structural view of a three-dimensional model of a battery pack according to an embodiment of the present invention;
FIG. 4 is a schematic structural view of a three-dimensional model of an anti-vibration assembly according to an embodiment of the present invention;
FIG. 5 is a schematic structural view of a finite element discrete model of a battery assembly according to an embodiment of the present invention;
Fig. 6 is a schematic structural view of a superunit model of a battery assembly according to an embodiment of the present invention;
FIG. 7 is a graph comparing the results of outputting first-order modal vibration frequencies of a method for detecting mechanical properties of a power battery according to an embodiment of the present invention with those of a conventional method;
FIG. 8 is a block diagram of a power cell mechanical property detection device according to an embodiment of the present invention;
fig. 9 is a schematic diagram of a hardware structure of a computer device according to an embodiment of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The embodiment of the invention provides a method for detecting the mechanical property of a power battery, which is used for establishing a superunit of a battery pack through a dynamic stiffness matrix so as to achieve the effect of quickly detecting the mechanical property of the battery pack.
According to an embodiment of the present invention, there is provided an embodiment of a method for detecting mechanical properties of a power battery, it should be noted that the steps illustrated in the flowchart of the drawings may be performed in a computer system such as a set of computer executable instructions, and that although a logic sequence is illustrated in the flowchart, in some cases, the steps illustrated or described may be performed in a different order than that illustrated herein.
In this embodiment, a method for detecting mechanical properties of a power battery is provided, as shown in fig. 1, and the process includes the following steps:
step S101, constructing an assembly model of the battery pack for finite element analysis, and dividing parts of the assembly model into a battery assembly and an anti-vibration assembly, the anti-vibration assembly being mounted outside the battery assembly.
Specifically, the first step is to build a three-dimensional model of the battery pack according to the characteristics of the battery pack and the assembly form of the battery pack, then grid-divide the three-dimensional model to generate an assembly simulation assembly model for finite element analysis, and the process can be implemented by corresponding software (including but not limited to Hypermesh software and ANSA software), and the implementation process is the prior art and is not repeated here. The model is then divided into two parts, a battery assembly as an irreplaceable part and an anti-vibration assembly as a replaceable part, the anti-vibration assembly being other parts mounted outside the battery assembly, in preparation for mechanical inspection of the subsequent battery pack. In the subsequent steps, aiming at the problem of great structural adjustment difficulty of the battery module in the practical application scene, the embodiment creates a superunit for the battery module, fixes the battery module, can output a plurality of structural design schemes only by developing vibration-resistant modules with various shapes and materials as replaceable parts, and can detect mechanical properties of various battery structural design schemes in a short time by replacing the vibration-resistant modules and repeatedly calculating mechanical property results by utilizing the reduced dynamic stiffness matrix.
In some optional embodiments, the step S101 includes:
step a1, constructing a battery tray, a liquid cooling plate, a plurality of battery modules and a bottom guard plate, wherein the liquid cooling plate is arranged above the battery modules, the bottom guard plate is arranged below the battery modules, the battery modules are uniformly arranged between the liquid cooling plate and the bottom guard plate, and the battery tray is arranged below the battery assembly;
and a2, dividing the structure formed by the liquid cooling plate, the battery module and the bottom guard plate into battery components, and dividing the battery tray into vibration-resistant components.
Specifically, as shown in fig. 2, according to the assembly form of the battery pack, the assembly model established in this embodiment at least includes a battery tray, a liquid cooling plate, a plurality of battery modules and a bottom protection plate (taking 4 battery modules as an example, the battery modules are located between the liquid cooling plate and the bottom protection plate, which is not shown in fig. 2). Aiming at the problem of great difficulty in adjusting the structure of the battery module in the practical application scene, as shown in fig. 3 and 4, the embodiment regards the structure formed by the liquid cooling plate, the battery module and the bottom guard plate as a whole, divides the structure into battery assemblies, and divides the battery tray into anti-vibration assemblies. In the subsequent steps, the embodiment can only use a plurality of different battery trays as replaceable parts (including but not limited to different materials and thicknesses of the battery trays or different shapes, lengths, widths and angles of the lifting lugs of the lower box body) through development, so that the plurality of tray design schemes and the reduced superunit components of the battery assembly can be respectively and integrally analyzed in a short time, the structural design scheme with the best mechanical property performance can be adopted, the mechanical property detection efficiency is improved, and meanwhile, the model design workload of a structural design engineer is reduced.
Step S102, acquiring attribute parameters of the assembly model, wherein the attribute parameters comprise material parameters and section attribute parameters.
Specifically, as the results of rigidity, quality and the like are required to be calculated in the superunit creation and finite element analysis processes, the attribute parameters of the assembly model are required to be used, and the step is necessary to prepare for the subsequent analysis step by acquiring the attribute parameters of the structural design model. The attribute parameters at least comprise material parameters and section attribute parameters, the specific materials of the assembly model are determined according to actual conditions, for example, the material parameters of the module base plate are set to be copper, aluminum or alloy mixed by a plurality of metals in proportion, the material parameters also comprise elastic modulus, poisson ratio, density, yield strength, tensile strength and the like, and the section attribute parameters are used for representing that the model is a beam, a shell or a solid and the like.
Step S103, defining a reduction parameter for the super unit reduction, and calculating a dynamic stiffness matrix reduced to the external interface of the battery component through the reduction parameter and the attribute parameter, wherein the dynamic stiffness matrix is used as the super unit for representing the battery component.
Specifically, the dynamic stiffness matrix algorithm is an emerging algorithm, and is currently used for vibration analysis in some complex structures, the essential idea is to generate a dynamic matrix at each loading frequency and then dynamically synthesize the dynamic matrix, and based on this, the embodiment provides a superunit generation algorithm combining a superunit idea and a dynamic stiffness method. Firstly, defining reduction parameters such as a loading frequency range, battery assembly external interface constraint and the like, then generating a rigidity matrix expression representing the battery assembly external interface according to the battery assembly external interface constraint, and finally carrying out dynamic rigidity matrix solving on the rigidity matrix expression by utilizing the defined parameters such as the loading frequency range, attribute parameters and the like based on a dynamic rigidity matrix algorithm, so that a complex battery assembly is reduced to the battery assembly external interface, a dynamic rigidity matrix regarded as a battery assembly superunit is obtained, and a new thought is provided for the mechanical property detection work of a power battery by carrying out subsequent mechanical property detection through the dynamic rigidity matrix.
In some alternative embodiments, the step S103 includes:
step b1, defining a vibration frequency solving range, a frequency sweep solving range and a reduction method parameter of a dynamic stiffness matrix, wherein the vibration frequency solving range and the frequency sweep solving range are used for determining the connection force of a connection point, and the connection point is a connection point between a battery assembly and an anti-vibration assembly;
step b2, defining boundary constraint conditions according to the connection points to obtain the degrees of freedom of the connection points;
step b3, defining control parameters for executing the reduction method in the solving process;
step b4, generating a motion equation representing the relation among the degree of freedom of the connection point, the connection force of the connection point and the dynamic stiffness matrix through control parameters;
and b5, calling a vibration frequency solving range, a sweep frequency solving range, a reduction method parameter, the degree of freedom of the connection point and an attribute parameter through control parameters, and solving a dynamic matrix of a motion equation to obtain a dynamic stiffness matrix.
Specifically, the present embodiment first defines a reduction parameter for reducing a dynamic matrix algorithm for generating superunits. The method specifically comprises a vibration frequency solving range, a sweep frequency solving range, a reduction method parameter and a boundary constraint condition. The vibration frequency solving range and the sweep frequency solving range are used for extracting different loading frequencies during dynamic matrix calculation, and considering that the embodiment is mainly aimed at the application scene of the vehicle power battery, in order to ensure the safety and the reliability of structural design in the vehicle scene, the embodiment adapts to the application scene of the vehicle power battery by calculating random vibration stress within 200Hz, so that the created superunit has higher accuracy, and the embodiment adopts the vibration frequency solving range of 1.5-2.0 times to be more suitable for analysis in a certain safety redundancy range, such as 0 Hz-300 Hz; in addition, according to the upper limit frequency required by random vibration analysis in the national standard of the battery pack, the function of each connecting point within 200Hz needs to be output, so that the frequency sweep solving range is set to be 0 Hz-200 Hz; the reduction method parameters specifically comprise a superunit keyword CDS (CDS represents a dynamic matrix superunit reduction method), a structural feature mode calculation method, transfer function output, a starting node number for structural feature mode matrix output and the like; the boundary constraint condition mainly includes the constraint creation of the connection points of the battery assembly and the anti-vibration assembly, specifically includes the positions of each connection point (usually, the connection point is a bolt connection, each bolt connection position may also be another connection mode, such as a clamping connection, but not limited to this, for example) and the movable degree of freedom direction of each connection point, as shown in fig. 5, which is a perspective view of a finite element model of the battery assembly, and in this embodiment, 6 space degrees of freedom are defined for each generated connection point, and the directions of representing the displacement of each connection point may be 6 directions, such as translational movement in three coordinate axis directions and rotational movement in three directions in a xyz rectangular coordinate system in space, or translational movement in three coordinate axis directions and translational movement in an oblique direction between two adjacent axes in the xyz rectangular coordinate system, so that the flexibility of creating superunit is improved by the numerical definition of 6 degrees of freedom. In addition, in this embodiment, each connection point in the battery assembly is connected by using a linear display unit, and since the superunit generated by the battery assembly is a parameter reduction matrix, the vibration frequency calculated in the subsequent mechanical analysis stage cannot be directly displayed, so in order to facilitate viewing and analysis of the calculation result, in this embodiment, a contour is established for the superunit by using a linear display unit (for example, a PLOTEL unit in Hypermesh, ANSA). Then, defining control parameters for executing the reduction method in the solving process, and defining the work to be executed in each step and what parameters to be called in each step in the program executing process through the control parameters, for example, defining the parameters to be called in one step as attribute parameters, wherein the control parameters specifically comprise AUTOMSET, AUTOSPC, CHECKEL and the like. AUTOMSET is a parameter used to convert the relative degrees of freedom of a rigid element in a model to independent degrees of freedom, AUTOSPC is a parameter used to automatically constrain stiffness singularities and near singularities with single point constraints, and CHECKEL is a parameter used to check the quality of a discrete element.
Then, the embodiment of the invention combines the connection point and the connection point degree of freedom defined in the steps, creates a superunit dynamics equation of the battery assembly, and converts the dynamics equation into a motion equation about the relation among the degree of freedom of the connection point, the connection force of the connection point and the dynamic stiffness matrix, wherein the dynamic stiffness matrix in the motion equation is to be solved and is a stiffness matrix expression representing the external interface of the battery assembly. And finally, calling a vibration frequency solving range and a sweep frequency solving range, adopting different loading frequencies to execute a reduction method, substituting the degree of freedom and attribute parameters of the required connection points in the calculation process, solving a dynamic matrix of a motion equation, namely generating a dynamic matrix under each loading frequency, and then dynamically synthesizing to obtain the dynamic stiffness matrix of the battery assembly. In the embodiment of the invention, the dynamic stiffness matrix contains all information in the calculated vibration frequency range, and the vibration-resistant component is matched with the superunit model corresponding to the dynamic stiffness matrix, so that the solving time can be accelerated.
In some alternative embodiments, step b4 above comprises:
creating a kinetic equation for a superunit as
Wherein K is ii (s) dynamic stiffness submatrices, K, representing complex numbers of degrees of freedom within superunits io (s) and K oi (s) dynamic stiffness submatrices representing complex numbers of degrees of freedom of coupling between the interior of the superunit and the connection points, K oo (s) dynamic stiffness submatrices representing complex numbers of degrees of freedom of connection points, u i Represents the degree of freedom in the superunit, u o Representing the degree of freedom of the connection point, f o (s) represents a connection force of the connection points, s represents a superunit;
decomposing the above formula (1) to obtain
K ii (s)u i (s)+K io (s)u o (s)＝0 (2)
K oi (s)u i (s)+K oo (s)u o (s)＝f o (s) (3)
Then, solving the equation (2) and the equation (3) simultaneously includes:
solving the formula (2) to obtain
u i (s)＝-K ii (s) -1 K io (s)u o (s) (4)
Then substituting the expression (4) into the expression (3), and further converting the expression form to obtain the following expression (5)
(K oo (s)-K oi (s)K ii (s) -1 K io (s))u o (s)＝f o (s) (5)
Finally, taking the rigidity component in the formula as a whole, and reducing the generated motion equation into
In the middle ofRepresenting a dynamic stiffness matrix reduced to the external interface of the battery assembly,/->
Specifically, the improved dynamic equation of the embodiment has the key point that the internal degree of freedom of the battery assembly is linked with the interface degree of freedom, so that a dynamic stiffness matrix expression at the interface of the battery assembly is solved and used for subsequent frequency and stress calculation. Through the above wayK in (B) oo (s)、K ii (s) and K io/oi (s) an expression form of the dynamic stiffness matrix can be determined, wherein K oo (s) obtaining through the boundary constraint condition defined in the step b 2; k (K) ii (s) can be found from the stiffness (elastic modulus) of the material itself in the model, the connections between the anti-vibration components (connections between nodes in discrete models after discretization, etc.); k (K) io/oi (s) may be defined by an adhesive or bolting connection between the interior and the interface. After the expression is determined, step b5 may influence the interface force f by calculating the interface connection point and the internal point at each frequency point (the frequency point is determined by the vibration frequency solving range and the sweep frequency solving range o (s) values), and finally calculating a final dynamic stiffness matrix by scaling singular value decomposition of the transfer function after rotational degrees of freedom.
Step S104, introducing the dynamic stiffness matrix into the anti-vibration component, and solving the mechanical property result of the assembly model.
Specifically, besides representing the rigidity attribute of the superunit, the embodiment of the invention introduces the connection relation parameter into the matrix through the actual connection relation between the superunit and the battery tray, so as to assemble the dynamic rigidity matrix and the rigidity matrix of the anti-vibration component and generate a new rigidity matrix. And further, the new rigidity matrix is utilized to carry out mechanical property analysis, and the mechanical property result of the assembly model is output. The specific process of mechanical property analysis by using the new stiffness matrix can be executed by using an analysis module in Hypermesh or ANSA software, and the module is in the prior art, which is not described in detail in this embodiment. When the calculation result has no obvious formal error, the calculation result is output, so that the engineering personnel is prompted to identify the problem frequency according to vibration calculation, and an optimal engineering solution is obtained. When the calculation result has obvious errors or loopholes, the calculation requirement is not met, so that the reduction parameters of the reduction model are corrected and checked, and the calculation is recalculated.
In some optional embodiments, the step S104 includes:
and c1, generating a superunit model based on the dynamic stiffness matrix.
And c2, assembling the superunit model and the vibration-resistant assembly into a whole model through connecting points.
Step c3, under the boundary condition of the connecting point, reestablishing a new mass matrix and a new stiffness matrix of the whole model according to the dynamic stiffness matrix and the mass matrix of the superunit model, wherein the mass matrix of the superunit model is determined by attribute parameters;
step c4, by the formulaAnd calculating the vibration frequency of the integral model, wherein f represents the vibration frequency of the integral model, belongs to the mechanical property result of the assembly model, K represents a new stiffness matrix, and M represents a new mass matrix.
Step c5, calculating the deformation of the integral model according to the external force by the following method
{δ} e ＝[K] -1 {F}
In { delta } e The displacement matrix is a displacement matrix of the connection point, represents the deformation of the whole model, F is external force, and K is a new stiffness matrix;
step c6, solving the strain of the integral model according to the displacement matrix of the connecting points through the following steps
{ε}＝[B]{δ} e
Wherein B is a geometric matrix, { epsilon } represents strain and belongs to the mechanical property result of the assembly model;
step c7, calculating the stress of the integral model by the following formula
{σ s }＝[E]{ε}
In sigma s And the stress is represented, the mechanical property result belongs to an assembly model, and E is the elastic modulus of the battery pack.
Specifically, the dynamic stiffness matrix is a parameter matrix, and cannot be visualized directly, and when the calculation of the dynamic stiffness matrix is finished, the analysis and solution parameters (including control parameters, superunit result output format, generally H3D format, including matrix and three-dimensional model) defined according to the parameter definition process output the superunit model corresponding to the dynamic stiffness matrix, as shown in fig. 6. And then assembling the superunit model and the finite element model of the battery tray, and assembling the superunit model and the finite element model of the battery tray based on each connection point according to the boundary constraint set by the steps to obtain an integral model, wherein the module_cds.h3d file is connected with the replaceable vibration-resistant component through keywords of ASSIGN, H3DDMIG, module and 'module_cds.h3d'. When the integral model is obtained, the dynamic stiffness matrix can be introduced into the finite element analysis and calculation process of the anti-vibration component according to the connection relation of the connection points, so that the new stiffness matrix of the integral model is calculated, and meanwhile, the mass matrix of the superunit and the mass matrix of the anti-vibration component are fused (the mass matrix can be directly determined by attribute parameters) to generate a new mass matrix, so that the new mass matrix and the new stiffness matrix of the integral model are obtained. And substituting the new mass matrix and the new stiffness matrix into the formulas of the steps c4 to c7, calculating the corresponding first-order modal vibration frequency (natural frequency), strain and stress of the integral model, and finally visually rendering the output first-order modal vibration frequency, strain and stress to observe the mechanical properties of the battery pack. In this embodiment, the interface force is an acceleration excitation force, and the external force can be obtained from the product of the mass and the acceleration, and the deformation can be further obtained. As shown in fig. 7, a contour diagram of a section mode vibration frequency of the whole battery pack assembly is calculated based on the created superunit model, and compared with the result of the traditional finite element method, fig. 7 shows that the first-order overall mode is 48.45Hz obtained by adopting the traditional method, the first-order overall mode is 48.54Hz obtained by adopting the dynamic matrix superunit method, and the difference is 0.17%, less than 5%, so that the requirements are met; meanwhile, through statistics, the calculation time of the superunit method is reduced from 7 hours, 30 minutes and 51 seconds to 3 minutes and 37 seconds, and the effect is very obvious.
It should be noted that some operating parameters are also set before performing the modal calculations and/or random vibration calculations in steps c4 to c 7. For the integral mode calculation of the battery pack, specifically, calculation output parameters (generally including vibration modes, vibration frequencies, strain energy and the like), working condition reference parameters (used for setting and calculating the boundaries and working conditions of the mode vibration frequencies, vibration modes and the like of the whole battery pack, generally including reference boundary condition keywords, namely the boundaries of the mounting points of the battery pack and a vehicle body bolt, the mode vibration frequency calculation keywords and the like), integral mode characteristic value keywords and integral mode calculation dynamic change part model reference parameters of the battery pack (such as a discrete model of a tray structure dynamically changed into various structures in the embodiment); for the calculation of the random vibration of the battery pack, the method specifically comprises superunit model results referencing the fixed part model, keywords used for calculating random vibration, result output keywords used for calculating random vibration (such as various stress results), parameters of calculation working conditions of random vibration of the battery pack (generally comprising whole battery pack binding boundary, whole modal vibration frequency, whole damping, excitation load, sweep frequency range and the like), parameters of calculation boundary of random vibration of the battery pack (generally comprising whole battery pack binding boundary, whole modal vibration frequency, whole damping, excitation load, sweep frequency range and the like), parameters of reference of dynamic change part model of random vibration calculation of the battery pack (such as tray structure discrete models of different structures in the embodiment).
Step S105, replacing the anti-vibration component in the assembly model, and returning to the step of introducing the dynamic stiffness matrix into the anti-vibration component to solve the mechanical property result of the assembly model.
Specifically, when the detection of one set of scheme is finished, the superunit model is kept unchanged, only the anti-vibration component in the assembly model is replaced, and the step S104 is repeatedly executed, so that the mechanical property detection of multiple sets of design schemes can be realized in a short time, and the optimal anti-vibration design structure is found out.
Defining a finite element assembly model of the power battery, determining an exchangeable anti-vibration component and an irreplaceable battery component, determining attribute parameters and reduction parameters of the model, reducing the battery component based on a dynamic matrix algorithm, and calculating a dynamic stiffness matrix reduced to an external interface of the battery component so as to represent a superunit of the external interface stiffness of the battery component; then introducing the dynamic stiffness matrix into an anti-vibration component, and integrally solving the mechanical performance results such as the natural frequency, stress, strain and the like of the assembly model; aiming at the problem of high structural adjustment difficulty of the battery module in an actual application scene, the embodiment can output a plurality of structural design schemes only by developing vibration-resistant components with various shapes and different materials as replaceable parts, and can detect mechanical properties of various battery structural design schemes in a short time by replacing the vibration-resistant components and repeatedly calculating mechanical property results by utilizing the reduced dynamic stiffness matrix, thereby remarkably improving the mechanical property detection efficiency of the power battery and reducing the model design workload of structural design engineers. Meanwhile, the dynamic stiffness matrix algorithm-based superunit which is reduced to the external interface of the battery assembly is calculated, so that a new thought is provided for the mechanical property detection work of the power battery.
The embodiment also provides a device for detecting the mechanical property of the power battery, which is used for realizing the embodiment and the preferred implementation manner, and is not described again. As used below, the term "module" may be a combination of software and/or hardware that implements a predetermined function. While the means described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware, is also possible and contemplated.
The device for detecting mechanical properties of a power battery provided in this embodiment, as shown in fig. 8, includes:
the finite element model construction module 801 is configured to construct an assembly model of the battery pack for finite element analysis, and divide parts of the assembly model into a battery assembly and an anti-vibration assembly, and the anti-vibration assembly is mounted outside the battery assembly. For details, refer to the related description of step S101 in the above method embodiment, and no further description is given here.
The parameter obtaining module 802 is configured to obtain attribute parameters of the assembly model, where the attribute parameters include material parameters and section attribute parameters. For details, refer to the related description of step S102 in the above method embodiment, and no further description is given here.
The superunit calculating module 803 is configured to define a reduction parameter for superunit reduction, and calculate a dynamic stiffness matrix reduced to the external interface of the battery assembly by the reduction parameter and the attribute parameter, where the dynamic stiffness matrix is used as a superunit representing the battery assembly. For details, see the description of step S103 in the above method embodiment, and the details are not repeated here.
The performance detection module 804 is configured to introduce the dynamic stiffness matrix into the anti-vibration component, and solve the mechanical performance result of the assembly model. For details, refer to the related description of step S104 in the above method embodiment, and no further description is given here.
The iteration detecting module 805 is configured to replace an anti-vibration component in the assembly model, and return to the step of introducing the dynamic stiffness matrix into the anti-vibration component to solve the mechanical performance result of the assembly model. For details, see the description of step S105 in the above method embodiment, and the details are not repeated here.
In this embodiment, a device for detecting mechanical properties of a power battery is presented as a functional unit, where the unit refers to an ASIC circuit, a processor and a memory that execute one or more software or firmware programs, and/or other devices that may provide the above functions.
Further functional descriptions of the above respective modules and units are the same as those of the above corresponding embodiments, and are not repeated here.
The embodiment of the invention also provides computer equipment, which is provided with the detection device for the mechanical properties of the power battery shown in the figure 8.
Referring to fig. 9, fig. 9 is a schematic structural diagram of a computer device according to an alternative embodiment of the present invention, as shown in fig. 9, the computer device includes: one or more processors 10, memory 20, and interfaces for connecting the various components, including high-speed interfaces and low-speed interfaces. The various components are communicatively coupled to each other using different buses and may be mounted on a common motherboard or in other manners as desired. The processor may process instructions executing within the computer device, including instructions stored in or on memory to display graphical information of the GUI on an external input/output device, such as a display device coupled to the interface. In some alternative embodiments, multiple processors and/or multiple buses may be used, if desired, along with multiple memories and multiple memories. Also, multiple computer devices may be connected, each providing a portion of the necessary operations (e.g., as a server array, a set of blade servers, or a multiprocessor system). One processor 10 is illustrated in fig. 9.
The processor 10 may be a central processor, a network processor, or a combination thereof. The processor 10 may further include a hardware chip, among others. The hardware chip may be an application specific integrated circuit, a programmable logic device, or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general-purpose array logic, or any combination thereof.
Wherein the memory 20 stores instructions executable by the at least one processor 10 to cause the at least one processor 10 to perform a method for implementing the embodiments described above.
The memory 20 may include a storage program area that may store an operating system, at least one application program required for functions, and a storage data area; the storage data area may store data created from the use of the computer device of the presentation of a sort of applet landing page, and the like. In addition, the memory 20 may include high-speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, flash memory device, or other non-transitory solid-state storage device. In some alternative embodiments, memory 20 may optionally include memory located remotely from processor 10, which may be connected to the computer device via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
Memory 20 may include volatile memory, such as random access memory; the memory may also include non-volatile memory, such as flash memory, hard disk, or solid state disk; the memory 20 may also comprise a combination of the above types of memories.
The computer device also includes a communication interface 30 for the computer device to communicate with other devices or communication networks.
The embodiments of the present invention also provide a computer readable storage medium, and the method according to the embodiments of the present invention described above may be implemented in hardware, firmware, or as a computer code which may be recorded on a storage medium, or as original stored in a remote storage medium or a non-transitory machine readable storage medium downloaded through a network and to be stored in a local storage medium, so that the method described herein may be stored on such software process on a storage medium using a general purpose computer, a special purpose processor, or programmable or special purpose hardware. The storage medium can be a magnetic disk, an optical disk, a read-only memory, a random access memory, a flash memory, a hard disk, a solid state disk or the like; further, the storage medium may also comprise a combination of memories of the kind described above. It will be appreciated that a computer, processor, microprocessor controller or programmable hardware includes a storage element that can store or receive software or computer code that, when accessed and executed by the computer, processor or hardware, implements the methods illustrated by the above embodiments.
Although embodiments of the present invention have been described in connection with the accompanying drawings, various modifications and variations may be made by those skilled in the art without departing from the spirit and scope of the invention, and such modifications and variations fall within the scope of the invention as defined by the appended claims.
Claims (10)
1. A method for detecting mechanical properties of a power battery, the method comprising:
constructing an assembly model of a battery pack for finite element analysis, and dividing parts of the assembly model into a battery assembly and an anti-vibration assembly, wherein the anti-vibration assembly is arranged outside the battery assembly;
acquiring attribute parameters of the assembly model, wherein the attribute parameters comprise material parameters and section attribute parameters;
defining a reduction parameter for superunit reduction, and calculating a dynamic stiffness matrix reduced to an external interface of the battery assembly through the reduction parameter and the attribute parameter, wherein the dynamic stiffness matrix is used as a superunit for representing the battery assembly;
introducing the dynamic stiffness matrix into the anti-vibration component, and solving the mechanical property result of the assembly model;
and replacing the anti-vibration component in the assembly model, and returning to the step of introducing the dynamic stiffness matrix into the anti-vibration component to solve the mechanical property result of the assembly model.
2. The method of claim 1, wherein constructing an assembly model of a battery pack for finite element analysis and dividing components of the assembly model into a battery assembly and an anti-vibration assembly comprises:
constructing a battery tray, a liquid cooling plate, a plurality of battery modules and a bottom guard plate as the assembly model, wherein the liquid cooling plate is arranged above the battery modules, the bottom guard plate is arranged below the battery modules, the battery modules are uniformly arranged between the liquid cooling plate and the bottom guard plate, and the battery tray is arranged below the battery module;
dividing the structure formed by the liquid cooling plate, the battery module and the bottom guard plate into battery components and dividing the battery tray into vibration-resistant components.
3. The method according to claim 1 or 2, wherein defining the curtailment parameters for superunit curtailment and calculating the dynamic stiffness matrix curtailed to the battery assembly external interface from the curtailment parameters and the attribute parameters, comprises:
defining a vibration frequency solving range, a frequency sweep solving range and a reduction method parameter of a dynamic stiffness matrix, wherein the vibration frequency solving range and the frequency sweep solving range are used for determining the connecting force of a connecting point, and the connecting point is a connecting point between the battery assembly and the anti-vibration assembly;
Defining boundary constraint conditions according to the connection points to obtain the degree of freedom of the connection points;
defining control parameters for executing a reduction method in a solving process;
generating a motion equation representing the relation among the degree of freedom of the connection point, the connection force of the connection point and the dynamic stiffness matrix through the control parameters;
and calling the vibration frequency solving range, the sweep frequency solving range, the reduction method parameters, the freedom degree of the connecting point and the attribute parameters through the control parameters so as to solve the dynamic matrix of the motion equation and obtain the dynamic stiffness matrix.
4. A method according to claim 3, wherein said generating, by means of said control parameters, an equation of motion representing the relation between the degrees of freedom of the connection points, the connection forces of the connection points and the dynamic stiffness matrix, comprises:
creating a kinetic equation for a superunit as
Wherein K is ii (s) dynamic stiffness submatrices, K, representing complex numbers of degrees of freedom within superunits iO (s) and K oi (s) dynamic stiffness submatrices representing complex numbers of degrees of freedom of coupling between the interior of the superunit and the connection points, K oO (s) dynamic stiffness submatrices representing complex numbers of degrees of freedom of connection points, u i Represents the degree of freedom in the superunit, u o Representing the degree of freedom of the connection point, f o (s) represents a connection force of the connection points, s represents a superunit;
decomposing the above formula to obtain
K ii (s)u i (s)+K io (s)u o (s)＝0
K oi (s)u i (s)+K oo (s)u o (s)＝f o (s)
The two formulas are combined and converted to obtain
(K oo (s)-K oi (s)K ii (s) -1 K io (s))u o (s)＝f o (s)
Reducing the generation of equations of motion to
In the middle ofRepresenting a dynamic stiffness matrix reduced to the external interface of the battery assembly,/->
5. The method of claim 3, wherein the introducing the dynamic stiffness matrix into the anti-vibration assembly, solving for mechanical property results of the assembly model, comprises:
generating a superunit model based on the dynamic stiffness matrix;
assembling the superunit model and the anti-vibration component into an integral model through a connecting point;
under the boundary condition of the connecting point, reestablishing a new mass matrix and a new stiffness matrix of the whole model according to the dynamic stiffness matrix and a mass matrix of a superunit model, wherein the mass matrix of the superunit model is determined by the attribute parameters;
through typeAnd calculating the vibration frequency of the integral model, wherein f represents the vibration frequency of the integral model, belongs to the mechanical property result of the assembly model, K represents the new stiffness matrix, and M represents the new mass matrix.
6. The method of claim 5, wherein said solving for mechanical property results of said assembly model further comprises:
Calculating the deformation of the integral model according to the external force by the following method
{δ} e ＝[K] -1 {F}
In { delta } e The displacement matrix is a displacement matrix of the connection point, the deformation of the whole model is represented, F is external force, and K is the new stiffness matrix;
solving the strain of the integral model according to the displacement matrix of the connecting points by
{ε}＝[B]{δ} e
Wherein B is a geometric matrix, { epsilon } represents strain and belongs to the mechanical property result of the assembly model;
calculating stress of the whole model by
{σ s }＝[E]{ε}
In sigma s And the stress is represented, the mechanical property result belongs to the assembly model, and E is the elastic modulus of the battery pack.
7. A method according to claim 3, wherein the vibration frequency solving range is 0 Hz-300 Hz, the sweep frequency solving range is 0 Hz-200 Hz, the degrees of freedom of the connection points comprise 6 spatial directions, and each connection point in the battery assembly is connected by a linear display unit.
8. A device for detecting mechanical properties of a power battery, the device comprising:
the finite element model construction module is used for constructing an assembly model of the battery pack for finite element analysis and dividing parts of the assembly model into a battery assembly and an anti-vibration assembly, and the anti-vibration assembly is arranged outside the battery assembly;
The parameter acquisition module is used for acquiring attribute parameters of the assembly model, wherein the attribute parameters comprise material parameters and section attribute parameters;
the superunit calculation module is used for defining a reduction parameter for superunit reduction, and calculating a dynamic stiffness matrix reduced to the external interface of the battery assembly through the reduction parameter and the attribute parameter, wherein the dynamic stiffness matrix is used as a superunit for representing the battery assembly;
the performance detection module is used for introducing the dynamic stiffness matrix into the anti-vibration component and solving the mechanical performance result of the assembly model;
and the iteration detection module is used for replacing the anti-vibration component in the assembly model and returning to the step of introducing the dynamic stiffness matrix into the anti-vibration component to solve the mechanical property result of the assembly model.
9. A computer device, comprising:
a memory and a processor in communication with each other, the memory having stored therein computer instructions which, upon execution, cause the processor to perform the method of any of claims 1 to 7.
10. A computer readable storage medium having stored thereon computer instructions for causing a computer to perform the method of any one of claims 1 to 7.
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