Energy absorption evaluation method of sandwich structure battery pack bottom protection plate based on strain energy analysis

Abstract

The application provides a sandwich structure battery pack bottom protection plate energy absorption evaluation method and system based on strain energy analysis, relates to the power battery pack protection technical field, and comprises the following steps: preparing a laminated sandwich structure bottom protection plate; calculating the unit volume strain energy of a composite skin, a foam core material and an embedded steel plate; determining the deformation region volume based on the Hertz contact theory; obtaining the total absorption energy through superposition integration; and determining the optimal structure parameters under the energy absorption requirements and deformation constraint conditions by using gradient optimization. The application can effectively evaluate the energy absorption performance of the battery pack bottom protection plate, realize lightweight design, and improve the safety of the battery pack.

Description

Technical Field

[0001] The present invention relates to the technical field of power battery pack protection, and in particular to a method and system for evaluating energy absorption of a sandwich-structured battery pack bottom guard plate based on strain energy analysis. Background Art

[0002] With the rapid development of the new energy vehicle industry, power battery pack safety has become a key industry concern. As a crucial protective component, the power battery pack underbody shield plays a crucial role in protecting the battery from impacts caused by road debris and damage. Traditional power battery pack underbody shields are mostly made of metal or simple composite materials. However, the balance between lightweight design and protective performance makes it difficult to meet increasingly stringent safety requirements.

[0003] As a highly efficient and lightweight structure, the sandwich structure is increasingly being adopted in the design of power battery pack underbody panels due to its excellent specific stiffness, specific strength, and energy absorption properties. This structure typically consists of two layers of high-strength composite skins and a lightweight core. This effectively combines the high strength of the surface material with the lightweight properties of the core, achieving overall lightweighting while maintaining structural strength.

[0004] However, the existing sandwich structure power battery pack bottom guard plate design has the following deficiencies: the existing design lacks an effective energy absorption assessment method, making it difficult to accurately predict the energy absorption performance of the bottom guard plate under impact loads, resulting in excessive safety redundancy or insufficient protection during the design process. Traditional assessment methods often rely on a large number of experimental verifications or simplified numerical simulations, which cannot deeply analyze the strain energy distribution of materials under complex stress states and make it difficult to achieve accurate structural optimization. Existing design methods make it difficult to comprehensively consider the synergistic effects of composite skins, foam cores, and embedded metal reinforcements, and cannot fully utilize the overall performance advantages of the sandwich structure, which restricts further improvements in the lightweight and energy absorption performance of the bottom guard plate. Summary of the Invention

[0005] The embodiments of the present invention provide a method and system for evaluating the energy absorption of a sandwich-structured battery pack bottom guard plate based on strain energy analysis, which can solve the problems in the prior art.

[0006] A first aspect of an embodiment of the present invention provides a method for evaluating energy absorption of a sandwich-structured battery pack bottom guard plate based on strain energy analysis, comprising:

[0007] Prepare a sandwich structure power battery pack bottom guard plate with an upper composite material skin, a foam core material, an embedded steel plate and a lower composite material skin stacked in sequence;

[0008] Determining a stress tensor and a strain tensor of the composite material skin based on an orthotropic constitutive relationship, and calculating a strain state and a unit volume strain energy of the composite material skin according to the stress tensor and the strain tensor;

[0009] Determining the principal elongation of the foam core material according to the strain state of the composite skin, substituting the principal elongation into the hyperelastic constitutive equation, and calculating the unit volume strain energy of the foam core material based on the stiffness coefficient and exponential coefficient of the foam core material;

[0010] Determining the yield stress of the embedded steel plate based on the deformation state of the composite skin and the foam core, and obtaining the unit volume strain energy of the embedded steel plate by integrating the yield stress from zero to the plastic strain;

[0011] Calculating the contact radius of the steel ball after impact deformation based on the Hertz contact theory formula, and determining the volume of the local deformation area according to the contact radius;

[0012] The unit volume strain energies of the upper composite skin, foam core, embedded steel plate and lower composite skin are superimposed and integrated within the volume of the local deformation area to obtain the total absorbed energy. The total absorbed energy is compared with the preset impact energy. Under the conditions of meeting the energy absorption requirements and deformation constraints, the gradient optimization method is used to determine the optimal structural parameters that minimize the weight of the sandwich structure power battery pack bottom guard plate.

[0013] Determining the stress tensor and strain tensor of the composite material skin based on the orthotropic constitutive relationship, and calculating the strain state and unit volume strain energy of the composite material skin according to the stress tensor and the strain tensor includes:

[0014] Obtaining a longitudinal elastic modulus, a transverse elastic modulus, and a main Poisson's ratio of the composite material skin, and generating a sixth-order stiffness matrix based on an orthotropic constitutive relationship between the longitudinal elastic modulus and the transverse elastic modulus and a coupling term between the main Poisson's ratio and the elastic modulus;

[0015] measuring a three-dimensional displacement field of the composite skin under an external load, taking partial derivatives of the three-dimensional displacement field along the X-axis, the Y-axis, and the Z-axis to obtain normal strain, taking mixed partial derivatives along the XY plane, the YZ plane, and the XZ plane to obtain shear strain, and combining the normal strain and the shear strain into a strain tensor;

[0016] extracting interlaminar shear deformation and bending deformation values ​​of the composite skin based on the strain tensor, and determining the strain state of the composite skin;

[0017] A matrix multiplication operation is performed on the strain tensor and the sixth-order stiffness matrix to obtain a stress tensor, and the stress tensor is divided by two and multiplied with the strain tensor to obtain the unit volume strain energy of the composite skin.

[0018] The principal elongation of the foam core is determined according to the strain state of the composite skin, the principal elongation is substituted into the hyperelastic constitutive equation, and the unit volume strain energy of the foam core is calculated based on the stiffness coefficient and exponential coefficient of the foam core, including:

[0019] Obtaining the stiffness coefficient and exponential coefficient of the foam core material; determining the first principal elongation, the second principal elongation, and the third principal elongation of the foam core material according to the strain state of the composite skin; substituting the first principal elongation, the second principal elongation, and the third principal elongation into the strain energy density equation, which is:

[0020] ;

[0021] in, U foam is the unit volume strain energy of the foam core material, i is the item number, N is the total number of items, m i is the stiffness coefficient of the foam core material, α i is the exponential coefficient of the foam core material, l 1 is the first principal elongation, l 2 is the second principal elongation, l 3 is the third principal elongation.

[0022] Determining the yield stress of the embedded steel plate based on the deformation state of the composite skin and the foam core, and integrating the yield stress from zero to the plastic strain to obtain the unit volume strain energy of the embedded steel plate includes:

[0023] The yield stress and plastic strain of the embedded steel plate are determined according to the deformation state of the composite skin and the foam core material. The yield stress and plastic strain are substituted into the strain energy formula of the embedded steel plate to calculate the unit volume strain energy of the embedded steel plate. The strain energy formula of the embedded steel plate is:

[0024] ;

[0025] in, U steel is the unit volume strain energy of the embedded steel plate, s y is the yield stress of the embedded steel plate, e p is the plastic strain of the embedded steel plate, e is the strain variable.

[0026] Calculating the contact radius of the steel ball after impact deformation based on the Hertz contact theory formula, and determining the volume of the local deformation area according to the contact radius includes:

[0027] Obtain the contact radius of the steel ball impact test, and substitute the contact radius into the Hertz contact theory formula to calculate the volume of the local deformation area caused by the impact deformation of the steel ball under impact test. The Hertz contact theory formula is:

[0028] ;

[0029] in, V impact is the volume of the local deformation area, R impact is the contact radius after impact deformation, and π is the pi.

[0030] The total absorbed energy is compared with the preset impact energy. Under the conditions of meeting the energy absorption requirements and deformation constraints, the optimal structural parameters for minimizing the weight of the sandwich structure power battery pack bottom guard plate are determined using a gradient optimization method, including:

[0031] Calculating the total weight of the sandwich structure power battery pack bottom guard plate by summing the product of the density and thickness of the upper composite material skin, the product of the density and thickness of the foam core material, the product of the density and thickness of the embedded steel plate, and the product of the density and thickness of the lower composite material skin;

[0032] Comparing the total absorbed energy with a preset energy absorption threshold of the sandwich structure power battery pack bottom guard plate to obtain a first judgment result, and comparing the maximum deformation of the sandwich structure power battery pack bottom guard plate with a critical deformation of the sandwich structure power battery pack bottom guard plate to obtain a second judgment result;

[0033] determining an optimization objective function according to the first judgment result and the second judgment result, and setting the total weight as the optimization objective function when the total absorbed energy is greater than the preset energy absorption threshold and the maximum deformation is less than the critical deformation;

[0034] Based on the gradient information of the optimization objective function, the optimization parameters of the thickness of the upper composite skin, the density and thickness of the foam core material, the thickness of the embedded steel plate and the thickness of the lower composite skin are iteratively updated until the optimization objective function converges to a minimum value, thereby obtaining the optimal structural parameters of the sandwich-structured power battery pack bottom guard plate.

[0035] A second aspect of an embodiment of the present invention provides an energy absorption assessment system for a sandwich-structured battery pack bottom guard plate based on strain energy analysis, comprising:

[0036] The first unit is used to prepare a sandwich structure power battery pack bottom guard plate, which is composed of an upper composite material skin, a foam core material, an embedded steel plate and a lower composite material skin stacked in sequence;

[0037] The second unit is used to determine the stress tensor and strain tensor of the composite material skin based on the orthotropic constitutive relationship, and calculate the strain state and unit volume strain energy of the composite material skin according to the stress tensor and the strain tensor;

[0038] a third unit for determining a principal elongation of the foam core material according to the strain state of the composite skin, substituting the principal elongation into a hyperelastic constitutive equation, and calculating a unit volume strain energy of the foam core material based on a stiffness coefficient and an exponential coefficient of the foam core material;

[0039] a fourth unit for determining a yield stress of the embedded steel plate based on the deformation state of the composite skin and the foam core, and obtaining a unit volume strain energy of the embedded steel plate by integrating the yield stress from zero to the plastic strain;

[0040] The fifth unit is used to calculate the contact radius of the steel ball after impact deformation in the impact test based on the Hertz contact theory formula, and determine the volume of the local deformation area according to the contact radius;

[0041] The sixth unit is used to superimpose the unit volume strain energy of the upper composite skin, foam core, embedded steel plate and lower composite skin and integrate it within the volume of the local deformation area to obtain the total absorbed energy, compare the total absorbed energy with the preset impact energy, and use the gradient optimization method to determine the optimal structural parameters that minimize the weight of the bottom guard plate of the sandwich structure power battery pack while meeting the energy absorption requirements and deformation constraints.

[0042] According to a third aspect of the embodiments of the present invention,

[0043] An electronic device is provided, comprising:

[0044] processor;

[0045] a memory for storing processor-executable instructions;

[0046] The processor is configured to call the instructions stored in the memory to execute the aforementioned method.

[0047] According to a fourth aspect of the embodiments of the present invention,

[0048] A computer-readable storage medium is provided, on which computer program instructions are stored. When the computer program instructions are executed by a processor, the method described above is implemented.

[0049] The present invention provides a method for evaluating the energy absorption of a sandwich-structured battery pack bottom guard plate based on strain energy analysis, which has the following beneficial effects:

[0050] By establishing a precise mechanical model of the composite skin, foam core and embedded steel plate and calculating the strain energy of each layer of material separately, the energy absorption performance of the sandwich structure bottom guard plate can be comprehensively and accurately evaluated, thereby improving the accuracy of the energy absorption assessment.

[0051] By determining the volume of the deformation area based on the Hertz contact theory and integrating the unit volume strain energy of each layer of material, a total absorbed energy that is more consistent with actual working conditions can be obtained, avoiding the errors caused by traditional simplified models and making the evaluation results more reliable.

[0052] The gradient optimization method is used to determine the optimal structural parameters while meeting the energy absorption requirements and deformation constraints, achieving a lightweight design of the battery pack bottom guard plate. This reduces the overall vehicle weight while ensuring safety and improves the range of electric vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 Schematic diagram of a flow chart of a method for evaluating energy absorption of a sandwich-structured battery pack bottom guard plate based on strain energy analysis according to an embodiment of the present invention;

[0054] Figure 2 This is a schematic diagram of the calculation process of the strain energy of composite skin;

[0055] Figure 3 Schematic diagram of the structure of the sandwich structure battery pack bottom guard plate energy absorption evaluation system based on strain energy analysis. DETAILED DESCRIPTION

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0057] The following specific embodiments are used to describe the technical solution of the present invention in detail. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0058] Figure 1 FIG. 1 is a flow chart of a method for evaluating energy absorption of a sandwich structure battery pack bottom guard plate based on strain energy analysis according to an embodiment of the present invention. Figure 1 As shown, the method includes:

[0059] Prepare a sandwich structure power battery pack bottom guard plate with an upper composite material skin, a foam core material, an embedded steel plate and a lower composite material skin stacked in sequence;

[0060] Determining a stress tensor and a strain tensor of the composite material skin based on an orthotropic constitutive relationship, and calculating a strain state and a unit volume strain energy of the composite material skin according to the stress tensor and the strain tensor;

[0061] Determining the principal elongation of the foam core material according to the strain state of the composite skin, substituting the principal elongation into the hyperelastic constitutive equation, and calculating the unit volume strain energy of the foam core material based on the stiffness coefficient and exponential coefficient of the foam core material;

[0062] Determining the yield stress of the embedded steel plate based on the deformation state of the composite skin and the foam core, and obtaining the unit volume strain energy of the embedded steel plate by integrating the yield stress from zero to the plastic strain;

[0063] Calculating the contact radius of the steel ball after impact deformation based on the Hertz contact theory formula, and determining the volume of the local deformation area according to the contact radius;

[0064] The unit volume strain energies of the upper composite skin, foam core, embedded steel plate and lower composite skin are superimposed and integrated within the volume of the local deformation area to obtain the total absorbed energy. The total absorbed energy is compared with the preset impact energy. Under the conditions of meeting the energy absorption requirements and deformation constraints, the gradient optimization method is used to determine the optimal structural parameters that minimize the weight of the sandwich structure power battery pack bottom guard plate.

[0065] In an optional embodiment, determining the stress tensor and strain tensor of the composite skin based on the orthotropic constitutive relationship, and calculating the strain state and unit volume strain energy of the composite skin according to the stress tensor and the strain tensor includes:

[0066] Obtaining a longitudinal elastic modulus, a transverse elastic modulus, and a main Poisson's ratio of the composite material skin, and generating a sixth-order stiffness matrix based on an orthotropic constitutive relationship between the longitudinal elastic modulus and the transverse elastic modulus and a coupling term between the main Poisson's ratio and the elastic modulus;

[0067] measuring a three-dimensional displacement field of the composite skin under an external load, taking partial derivatives of the three-dimensional displacement field along the X-axis, the Y-axis, and the Z-axis to obtain normal strain, taking mixed partial derivatives along the XY plane, the YZ plane, and the XZ plane to obtain shear strain, and combining the normal strain and the shear strain into a strain tensor;

[0068] extracting interlaminar shear deformation and bending deformation values ​​of the composite skin based on the strain tensor, and determining the strain state of the composite skin;

[0069] A matrix multiplication operation is performed on the strain tensor and the sixth-order stiffness matrix to obtain a stress tensor, and the stress tensor is divided by two and multiplied with the strain tensor to obtain the unit volume strain energy of the composite skin.

[0070] like Figure 2 As shown, the method includes:

[0071] This embodiment provides a method for determining the stress tensor and strain tensor of a composite material skin based on an orthotropic constitutive relationship. The method is used to calculate the strain state and unit volume strain energy of the composite material skin.

[0072] In this embodiment, the calculation process of the strain state and unit volume strain energy of the composite skin is as follows. The material parameters of the composite skin are obtained, including the longitudinal elastic modulus E1, the transverse elastic modulus E2, and the main Poisson's ratio v12. For example, for a carbon fiber reinforced composite skin, its longitudinal elastic modulus E1 is 140GPa, the transverse elastic modulus E2 is 10GPa, and the main Poisson's ratio v12 is 0.3. Based on the obtained material parameters, a sixth-order stiffness matrix C is constructed according to the orthotropic constitutive relation. During the construction process, the coupling terms between the elastic moduli need to be considered. For example, the secondary Poisson's ratio v21 can be calculated by the relationship v21=v12×E2 / E1. In this example, v21=0.0214.

[0073] The sixth-order stiffness matrix C is a 6×6 matrix, where C11 = E1 / (1-v12 × v21), C22 = E2 / (1-v12 × v21), C12 = v12 × E2 / (1-v12 × v21), and C66 = G12. Other nonzero elements are determined based on the orthotropic properties of the material. Using the above parameters, we calculate C11 = 140.43 GPa, C22 = 10.03 GPa, and C12 = 3.01 GPa. If the shear modulus G12 is not directly measured, it can be estimated using the empirical formula G12 = E2 / (2 × (1 + 0.6)). In this example, G12 ≈ 3.13 GPa.

[0074] The three-dimensional displacement field of the composite skin under external load is measured using a 3D digital image correlation system or laser interferometer. These displacements are represented by u(x, y, z), v(x, y, z), and w(x, y, z), representing the displacements along the X, Y, and Z axes, respectively. For example, at a test point (10 mm, 15 mm, 0 mm), the displacements measured are u = 0.05 mm, v = 0.03 mm, and w = 0.01 mm.

[0075] The partial derivatives of the measured three-dimensional displacement field are calculated to calculate the normal strain and shear strain. The normal strain includes ε xx , ε yy and ε zz , obtained by taking partial derivatives of u with respect to x, v with respect to y, and w with respect to z. Shear strain includes γ xy , γ yz and γ xz , which is obtained by summing the mixed partial derivatives of u with respect to y and v with respect to x, v with respect to z and w with respect to y, u with respect to z and w with respect to x. At the above test point, ε is calculated by the finite difference method. xx =0.002, ε yy =0.001,ε zz =0.0005, γ xy =0.0015, γ yz =0.001, γ xz =0.0008.

[0076] The calculated normal strain and shear strain are combined into the strain tensor ε = [ε xx ,ε yy ,ε zz ,γ xy ,γ yz ,γ xz ] T Based on the strain tensor, the interlaminar shear deformation and bending deformation values ​​of the composite skin are extracted. The interlaminar shear deformation is mainly reflected in the γ xz and γ yz The bending deformation is analyzed by ε xx , ε yy and ε zz The rate of change along the thickness direction is determined. In this case, the interlaminar shear deformation γ xz =0.0008, γ yz =0.001, indicating that there is a small interlayer shear effect at this test point; by analyzing ε xx The gradient in the thickness direction is 0.0001 / mm, indicating the presence of slight bending deformation.

[0077] Based on the extracted deformation data, the strain state of the composite skin is determined. In this example, due to the xz and γ yz The value is small, and ε xx The gradient in the thickness direction is small, which indicates that the skin is mainly subjected to in-plane tensile strain at the test point, and the interlayer shear and bending deformations are relatively small.

[0078] Perform matrix multiplication of the strain tensor ε and the sixth-order stiffness matrix C to obtain the stress tensor σ=C×ε. In this example, the calculated σxx =281.1MPa,σ yy =13.1MPa,σ zz =5.0MPa, τ xy =4.7MPa, τ yz =3.1MPa, τ xz =2.5MPa.

[0079] Finally, the unit volume strain energy U of the composite skin is calculated. The unit volume strain energy is equal to the stress tensor divided by two and then multiplied by the strain tensor, that is, U=0.5×σ T ×ε. In this example, the calculated strain energy per unit volume is U=0.318J / mm 3 .

[0080] Using this method, the stress and strain tensors of the composite skin were successfully determined based on the orthotropic constitutive relation, and the strain state and strain energy per unit volume were calculated. These data are important for assessing the structural response and damage risk of composite skins under external loads, and can provide strong support for design optimization and safety assessment of composite skins.

[0081] In an optional embodiment, the principal elongation of the foam core is determined according to the strain state of the composite skin, the principal elongation is substituted into the hyperelastic constitutive equation, and the unit volume strain energy of the foam core is calculated based on the stiffness coefficient and exponential coefficient of the foam core, including:

[0082] Obtaining the stiffness coefficient and exponential coefficient of the foam core material; determining the first principal elongation, the second principal elongation, and the third principal elongation of the foam core material according to the strain state of the composite skin; substituting the first principal elongation, the second principal elongation, and the third principal elongation into the strain energy density equation, which is:

[0083] ;

[0084] in, U foam is the unit volume strain energy of the foam core material, i is the item number, N is the total number of items, m i is the stiffness coefficient of the foam core material, α i is the exponential coefficient of the foam core material, l 1 is the first principal elongation, l 2 is the second principal elongation, l 3is the third principal elongation.

[0085] In this embodiment, the stiffness coefficient and exponential coefficient of the foam core material need to be obtained first. These coefficients can usually be obtained by performing material testing on the foam core material. For example, the stress-strain relationship under different deformation states can be obtained by performing uniaxial tension, biaxial tension, or volume compression tests on the foam core material. The stiffness coefficient μ can then be obtained by data fitting. i and exponential coefficient α i In a specific example, for a polyurethane foam core material, three Ogden model parameters can be obtained: μ1=0.0326 MPa, α1=3.25; μ2=0.0033 MPa, α2=5.32; μ3=-0.0054 MPa, α3=-2.17.

[0086] Next, the first, second, and third principal elongations λ1, λ2, and λ3 of the foam core are determined based on the strain state of the composite skin. In practical applications, the presence of a bonding interface between the composite skin and the foam core ensures that the surface deformation of the foam core is consistent with that of the skin. Therefore, the principal elongations of the foam core can be determined by measuring or calculating the principal strains of the composite skin and then considering the deformation coordination between the foam core and the skin.

[0087] For example, in one embodiment, when the strain of the composite skin in the x-axis direction is ε x =0.05, the strain in the y-axis direction is ε y =0.03, and assuming that the foam core material is incompressible, the principal elongation of the foam core can be calculated as: λ1=1+ε x =1.05,λ2=1+ε y =1.03,λ3=1 / [(1+ε x )×(1+ε y )]=1 / (1.05×1.03)≈0.924.

[0088] After determining the principal elongations of the foam core, these principal elongations are substituted into the strain energy density equation to calculate the unit volume strain energy of the foam core. The strain energy density equation is expressed as U foam The calculation formula includes the stiffness coefficient μ of the foam core material i , exponential coefficient α i and three principal elongations λ1, λ2, and λ3.

[0089] The specific calculation process is as follows: For each item i, calculate α of λ1 i α of power, λ2 i α of the power and λ3 iThen add the three and subtract 3, then multiply by 2μ i / α i Finally, add up the results of all items to get the unit volume strain energy U of the foam core material foam .

[0090] Taking the parameters and principal elongation of the polyurethane foam core material as an example, when calculating the first term, substitute λ1=1.05, λ2=1.03, and λ3=0.924 to obtain (1.05 3.25 +1.03 3.25 +0.924 3.25 -3)×2×0.0326 / 3.25≈0.00192MPa. The second and third terms are calculated using the same method, yielding 0.00061 MPa and -0.00088 MPa, respectively. Adding the three results yields the unit volume strain energy U of the foam core. foam =0.00165 MPa.

[0091] This unit volume strain energy can be used to subsequently analyze the deformation energy, stress distribution, and structural stability of the composite structure. By adjusting the material parameters of the foam core or the design of the composite structure, the mechanical properties of the structure can be optimized, improving its load-bearing capacity and service life.

[0092] In engineering applications, this method can be used for the design and analysis of composite structures in fields such as aerospace, wind energy, and automotive. For example, when designing wings or blades with composite sandwich structures, this method can be used to predict the deformation response and strain energy distribution of the structure under different loading conditions, thereby optimizing the structural design and improving its mechanical properties and reliability.

[0093] It is worth noting that the accuracy of this method depends on the suitability of the hyperelastic constitutive model used and the accuracy of the stiffness coefficient and exponent coefficient. In practical applications, material testing of specific foam core materials is necessary to obtain more accurate material parameters. Furthermore, different hyperelastic constitutive models can be selected based on actual needs, such as the Neo-Hookean model, the Mooney-Rivlin model, or the higher-order Ogden model, to more accurately describe the mechanical behavior of the foam core material.

[0094] Furthermore, when the foam core is subjected to large deformations, plastic deformation or damage may occur, requiring a more complex material model to describe its nonlinear mechanical behavior. In this case, damage parameters or plasticity parameters can be introduced on top of the hyperelastic model to more accurately predict the mechanical response of the foam core under large deformation conditions.

[0095] In an optional embodiment, determining the yield stress of the embedded steel plate based on the deformation state of the composite skin and the foam core, and integrating the yield stress from zero to the plastic strain to obtain the unit volume strain energy of the embedded steel plate includes:

[0096] The yield stress and plastic strain of the embedded steel plate are determined according to the deformation state of the composite skin and the foam core material. The yield stress and plastic strain are substituted into the strain energy formula of the embedded steel plate to calculate the unit volume strain energy of the embedded steel plate. The strain energy formula of the embedded steel plate is:

[0097] ;

[0098] in, U steel is the unit volume strain energy of the embedded steel plate, s y is the yield stress of the embedded steel plate, e p is the plastic strain of the embedded steel plate, e is the strain variable.

[0099] In this embodiment, we will describe in detail how to determine the yield stress of the embedded steel plate based on the deformation state of the composite skin and foam core, and how to integrate the yield stress from zero to the plastic strain to obtain the unit volume strain energy of the embedded steel plate.

[0100] The deformation state of composite skins and foam cores can be determined through experimental measurements or finite element analysis. For example, a typical sandwich structure consists of two carbon fiber composite skins, a polyurethane foam core in between, and a 2 mm thick steel plate embedded within. During bending load testing, displacement sensors are used to measure the deformation of the structure under varying loads, while strain gauges are used to measure the strain in the composite skins and foam core.

[0101] When the maximum strain of the composite skin is measured to be 0.0125 and the maximum strain of the foam core is 0.0350, the actual strain of the embedded steel plate can be calculated based on the principles of material mechanics and deformation coordination conditions. Taking into account the interfacial bonding and force transfer characteristics, the strain of the embedded steel plate can be approximated to 0.0200.

[0102] According to the material characteristic curve of the embedded steel plate, when the strain reaches 0.0200, it can be determined that the steel plate has entered the plastic deformation stage. For a commonly used Q235 steel plate, its initial yield stress is usually 235 MPa. However, during actual stress, due to the work hardening effect, the yield stress will increase with the increase of plastic deformation.

[0103] The strain hardening law must be considered to determine the yield stress of the embedded steel plate. For Q235 steel, a bilinear hardening model can be used to describe its stress-strain relationship. When the strain is 0.0200, the yield stress at this time is approximately 275 MPa by looking up the table or interpolating the value. The plastic strain here can be calculated as the total strain minus the elastic strain, that is, 0.0200 minus 235 MPa divided by the elastic modulus of the steel plate (approximately 210 GPa), to obtain the plastic strain ε p About 0.0189.

[0104] After determining the yield stress and plastic strain of the embedded steel plate, the next step is to calculate the strain energy per unit volume. According to the principles of material mechanics, the strain energy per unit volume can be understood as the area under the stress-strain curve. For elastic-plastic materials, this energy consists of two components: elastic strain energy and plastic strain energy.

[0105] During the calculation process, the elastic strain energy is first calculated, which is the square of the initial yield stress divided by twice the elastic modulus, which is 235 MPa squared divided by 420 GPa, which is approximately 0.1314 MJ / m3. The plastic strain energy is then calculated by integrating the yield stress from the initial yield point to the final plastic strain point.

[0106] For simplified calculations, it is assumed that the stress-strain relationship of the steel in the plastic stage is linear hardening, and the hardening modulus is 1 / 50 of the elastic modulus, that is, 4.2 GPa. Then, during the plastic deformation process, the stress increases from 235 MPa to 275 MPa, and the corresponding plastic strain increases from 0 to 0.0189.

[0107] The plastic strain energy of this process can be approximated as the average yield stress multiplied by the plastic strain, that is, (235 + 275) / 2 multiplied by 0.0189, which is approximately 4.8195 MJ per cubic meter. Therefore, the total unit volume strain energy of the steel plate is the sum of the elastic strain energy and the plastic strain energy, which is approximately 4.9509 MJ per cubic meter.

[0108] To verify the accuracy of the calculations in practice, static compression tests were conducted to measure the force-displacement curve of the entire sandwich structure. The strain energy of the embedded steel plate was then inferred using the principle of conservation of energy. In a set of comparative tests, the experimentally measured strain energy per unit volume of the embedded steel plate was 5.0 megajoules per cubic meter, which differed from the theoretically calculated value by approximately 1%, validating the effectiveness of the calculation method.

[0109] This calculation method can also be extended to apply to embedded steel plates of varying thickness and deformation states. For example, when the thickness of the embedded steel plate increases to 3 mm, the strain of the plate decreases to 0.0180 under the same external load, and the calculated strain energy per unit volume is approximately 3.8 MJ / m³.

[0110] This method, based on the deformation state of the composite skin and foam core, determines the yield stress of the embedded steel plate and calculates the strain energy per unit volume. This method provides an important reference for optimizing the design of sandwich structures. By adjusting the thickness, material, or position of the embedded steel plate, the deformation characteristics and energy absorption capacity of the structure can be effectively controlled to meet the needs of different application scenarios.

[0111] In an optional embodiment, the contact radius of the steel ball after impact deformation in the impact test is calculated based on the Hertz contact theory formula, and the volume of the local deformation area is determined according to the contact radius, which includes:

[0112] Obtain the contact radius of the steel ball impact test, and substitute the contact radius into the Hertz contact theory formula to calculate the volume of the local deformation area caused by the impact deformation of the steel ball under impact test. The Hertz contact theory formula is:

[0113] ;

[0114] in, V impact is the volume of the local deformation area, R impact is the contact radius after impact deformation, and π is the pi.

[0115] The technical solution of the present invention first requires obtaining contact radius data from a steel ball impact test. In practice, the contact area between the steel ball and the impacted object after impact can be measured using high-precision measuring equipment. For example, an optical microscope, 3D profilometer, or other precision measuring instrument can be used to observe and measure the indentation formed after impact, obtain the diameter of the contact area, and then calculate the contact radius. To ensure data accuracy, multiple measurements can be taken at different angles and averaged.

[0116] After obtaining the contact radius, substitute it into the Hertz contact theory formula to calculate the volume of the local deformation area. According to Hertz contact theory, when two elastic bodies come into contact, deformation occurs near the contact area. For impact deformation, the volume of the local deformation area can be calculated by multiplying the cube of the contact radius by pi. Specifically, the volume of the local deformation area is equal to the cube of the contact radius multiplied by pi.

[0117] The following example illustrates this calculation process using specific data: Assuming the contact radius after the steel ball impact is measured to be 2 mm, and pi is 3.14159, then using the above formula, multiplying the contact radius of 2 mm to the power of 8 cubic millimeters by pi 3.14159 yields the volume of the local deformation area, approximately 25.13272 cubic millimeters.

[0118] To improve calculation accuracy, multiple impact tests can be performed and their statistical patterns analyzed. For example, 10 impact tests can be conducted under the same conditions, the contact radius can be measured for each test, the volume of the corresponding local deformation area can be calculated, and the data distribution can be analyzed to obtain more reliable results.

[0119] In practice, factors affecting contact radius measurement accuracy include measurement equipment accuracy, ambient temperature, and surface condition. To minimize errors, the following measures can be taken: use calibrated, high-precision measuring equipment; perform measurements in a constant temperature environment; ensure that both the steel ball and the impacted surface are clean and free of impurities; and employ standardized measurement procedures and methods.

[0120] The advantage of the method is that it can calculate the volume of complex local deformation areas through simple contact radius measurement, avoiding the difficulty of directly measuring the deformation volume. This is of great significance for analyzing the deformation behavior of materials under impact loads and evaluating their impact resistance.

[0121] In engineering applications, this method can be used to analyze the deformation characteristics of different materials under impact loads. For example, for a bearing steel ball with an HRC60 hardness, at an impact velocity of 5 m / s, the measured contact radius is 1.5 mm, and the calculated local deformation volume is approximately 10.60286 cubic millimeters. However, when the impact velocity is increased to 10 m / s, the measured contact radius is 2.3 mm, and the calculated local deformation volume is approximately 38.79233 cubic millimeters. By comparing the calculation results under different conditions, the influence of impact velocity on deformation volume can be analyzed.

[0122] This method can also be applied to quality control. Standardized impact testing and contact radius measurements can be used to assess material uniformity and consistency. For example, if the calculated deformation volumes after impact testing for steel samples from the same batch differ significantly, this indicates inhomogeneity in material properties, necessitating further inspection and analysis.

[0123] Furthermore, this method can be used for material development and optimization. By conducting impact tests on materials with different compositions and heat treatment processes, measuring the contact radius and calculating the deformation volume, the impact of material formulation or process improvements on impact resistance can be evaluated, providing a basis for material development.

[0124] To verify the accuracy of this method, cross-validation can be performed through finite element analysis or other experimental methods. For example, finite element software can be used to simulate the impact process under the same conditions, calculate the volume of the deformed area, and compare it with the result calculated based on the contact radius. In one verification case, for an impact with a contact radius of 2.5 mm, the deformation volume calculated based on the contact radius was 49.08984 cubic millimeters, while the finite element analysis result was 48.75 cubic millimeters. The relative error was less than 1%, indicating the high accuracy of this method.

[0125] In summary, this paper provides a method for calculating the volume of the local deformation zone by measuring the contact radius during a steel ball impact test, based on the Hertz contact theory formula. This method is simple to operate and offers accurate calculations, making it widely applicable in fields such as material performance evaluation, quality control, and material development.

[0126] In an optional embodiment, the total absorbed energy is compared with a preset impact energy, and a gradient optimization method is used to determine the optimal structural parameters for minimizing the weight of the sandwich structure power battery pack bottom guard plate while satisfying energy absorption requirements and deformation constraints, including:

[0127] Calculating the total weight of the sandwich structure power battery pack bottom guard plate by summing the product of the density and thickness of the upper composite material skin, the product of the density and thickness of the foam core material, the product of the density and thickness of the embedded steel plate, and the product of the density and thickness of the lower composite material skin;

[0128] Comparing the total absorbed energy with a preset energy absorption threshold of the sandwich structure power battery pack bottom guard plate to obtain a first judgment result, and comparing the maximum deformation of the sandwich structure power battery pack bottom guard plate with a critical deformation of the sandwich structure power battery pack bottom guard plate to obtain a second judgment result;

[0129] determining an optimization objective function according to the first judgment result and the second judgment result, and setting the total weight as the optimization objective function when the total absorbed energy is greater than the preset energy absorption threshold and the maximum deformation is less than the critical deformation;

[0130] Based on the gradient information of the optimization objective function, the optimization parameters of the thickness of the upper composite skin, the density and thickness of the foam core material, the thickness of the embedded steel plate and the thickness of the lower composite skin are iteratively updated until the optimization objective function converges to a minimum value, thereby obtaining the optimal structural parameters of the sandwich-structured power battery pack bottom guard plate.

[0131] In this example, a gradient optimization method was used to determine the optimal structural parameters for a sandwich-structured power battery pack underbody panel, minimizing its weight while meeting energy absorption requirements and deformation constraints. The sandwich-structured power battery pack underbody panel comprises a four-layer structure: an upper composite skin, a foam core, an embedded steel plate, and a lower composite skin.

[0132] In order to determine the optimal structural parameters to minimize the weight of the sandwich structure power battery pack bottom guard plate, it is necessary to calculate the total weight of the sandwich structure power battery pack bottom guard plate. The total weight is calculated by adding the product of the density and thickness of the upper composite skin, the density and thickness of the foam core, the density and thickness of the embedded steel plate, and the density and thickness of the lower composite skin. For example, assuming the density of the upper composite skin is 1500 kg / m 3 , thickness is 2 mm; density of foam core is 100 kg / m 3 , thickness is 20 mm; density of embedded steel plate is 7850 kg / m 3 , thickness is 1 mm; the density of the lower composite skin is 1500 kg / m 3 , with a thickness of 2 mm, the total weight per unit area of ​​the sandwich structure power battery pack bottom guard plate is 1500×0.002+100×0.02+7850×0.001+1500×0.002=14.85 kg / m 2 .

[0133] Before structural optimization, the total absorbed energy and maximum deformation of the sandwich-structured power battery pack under impact loads must be calculated using methods such as finite element analysis. The total absorbed energy refers to the sum of the energy absorbed by each layer of the underbody under impact, while the maximum deformation refers to the maximum displacement of the underbody under impact. For example, under specific impact conditions, finite element analysis shows that the total absorbed energy of the sandwich-structured power battery pack underbody is 5000 J, and the maximum deformation is 15 mm.

[0134] During the optimization process, constraints on the total absorbed energy and maximum deformation are required. The calculated total absorbed energy is compared with the preset energy absorption threshold to obtain the first judgment result. The calculated maximum deformation is compared with the critical deformation to obtain the second judgment result. Assuming the preset energy absorption threshold is 4500 J and the critical deformation is 20 mm, the first judgment result indicates that the total absorbed energy exceeds the preset energy absorption threshold, while the second judgment result indicates that the maximum deformation is less than the critical deformation.

[0135] The optimization objective function is determined based on the first and second judgment results. When the total absorbed energy is greater than the preset energy absorption threshold and the maximum deformation is less than the critical deformation, the total weight is set as the optimization objective function. In the above example, since the total absorbed energy of 5000 J is greater than the preset energy absorption threshold of 4500 J and the maximum deformation of 15 mm is less than the critical deformation of 20 mm, the total weight of 14.85 kg / m 2 Set as the optimization objective function.

[0136] The structural parameters are iteratively updated based on the gradient of the optimization objective function. The optimized parameters include the thickness of the upper composite skin, the density and thickness of the foam core, the thickness of the embedded steel plate, and the thickness of the lower composite skin. During each iteration, the gradient of the objective function relative to each optimized parameter is used to adjust the parameter values ​​appropriately, aligning the objective function toward its minimum value.

[0137] An example of the optimization iteration process: In the first iteration, the thickness of the upper composite skin was adjusted to 1.8 mm and the density of the foam core was adjusted to 95 kg / m 3 The thickness of the foam core is adjusted to 19 mm, the thickness of the embedded steel plate is adjusted to 0.9 mm, and the thickness of the lower composite skin is adjusted to 1.8 mm. The new total weight is calculated to be 13.31 kg / m 2 Through finite element analysis, it was calculated that the total absorbed energy of the new structure was 4800 J and the maximum deformation was 16 mm, which still met the constraints.

[0138] In the second iteration, the parameters were further adjusted, the thickness of the upper composite skin was adjusted to 1.7 mm, and the density of the foam core was adjusted to 90 kg / m 3 The thickness of the foam core is adjusted to 18 mm, the thickness of the embedded steel plate is adjusted to 0.85 mm, and the thickness of the lower composite skin is adjusted to 1.7 mm. The new total weight is calculated to be 12.30 kg / m 2 Through finite element analysis, it was calculated that the total absorbed energy of the new structure was 4650 J and the maximum deformation was 17.5 mm, which still met the constraints.

[0139] In the third iteration, the parameters were adjusted further. The thickness of the upper composite skin was adjusted to 1.65 mm, and the density of the foam core was adjusted to 88 kg / m 3 The thickness of the foam core is adjusted to 17.5 mm, the thickness of the embedded steel plate is adjusted to 0.82 mm, and the thickness of the lower composite skin is adjusted to 1.65 mm. The new total weight is calculated to be 11.84 kg / m 2 Through finite element analysis, it was calculated that the total absorbed energy of the new structure was 4520 J and the maximum deformation was 19.5 mm, which still met the constraints.

[0140] The iterative process continues until the optimization objective function converges to a minimum, meaning the total weight no longer decreases significantly or the preset convergence accuracy is reached. The resulting parameter combination is the optimal structural parameters for the sandwich-structured power battery pack underbody. In this example, after multiple iterations, the optimal structural parameters were determined to be: an upper composite skin thickness of 1.65 mm and a foam core density of 88 kg / m 3 The foam core is 17.5 mm thick, the embedded steel plate is 0.82 mm thick, and the lower composite skin is 1.65 mm thick, corresponding to a total weight of 11.84 kg / m 2 , the total absorbed energy is 4520J and the maximum deformation is 19.5 mm.

[0141] This method uses a gradient optimization algorithm to find the optimal structural parameters, effectively reducing the weight of the sandwich-structured power battery pack bottom guard plate, while ensuring it has sufficient energy absorption and deformation control capabilities, thereby improving the safety and energy utilization efficiency of electric vehicles.

[0142] Figure 3 The structure diagram of the sandwich structure battery pack bottom guard plate energy absorption assessment system based on strain energy analysis is shown in FIG. The sandwich structure battery pack bottom guard plate energy absorption assessment system based on strain energy analysis according to an embodiment of the present invention includes:

[0143] The first unit is used to prepare a sandwich structure power battery pack bottom guard plate, which is composed of an upper composite material skin, a foam core material, an embedded steel plate and a lower composite material skin stacked in sequence;

[0144] The second unit is used to determine the stress tensor and strain tensor of the composite material skin based on the orthotropic constitutive relationship, and calculate the strain state and unit volume strain energy of the composite material skin according to the stress tensor and the strain tensor;

[0145] a third unit for determining a principal elongation of the foam core material according to the strain state of the composite skin, substituting the principal elongation into a hyperelastic constitutive equation, and calculating a unit volume strain energy of the foam core material based on a stiffness coefficient and an exponential coefficient of the foam core material;

[0146] a fourth unit for determining a yield stress of the embedded steel plate based on the deformation state of the composite skin and the foam core, and obtaining a unit volume strain energy of the embedded steel plate by integrating the yield stress from zero to the plastic strain;

[0147] The fifth unit is used to calculate the contact radius of the steel ball after impact deformation in the impact test based on the Hertz contact theory formula, and determine the volume of the local deformation area according to the contact radius;

[0148] The sixth unit is used to superimpose the unit volume strain energy of the upper composite skin, foam core, embedded steel plate and lower composite skin and integrate it within the volume of the local deformation area to obtain the total absorbed energy, compare the total absorbed energy with the preset impact energy, and use the gradient optimization method to determine the optimal structural parameters that minimize the weight of the bottom guard plate of the sandwich structure power battery pack while meeting the energy absorption requirements and deformation constraints.

[0149] According to a third aspect of an embodiment of the present invention, an electronic device is provided, including:

[0150] processor;

[0151] a memory for storing processor-executable instructions;

[0152] The processor is configured to call the instructions stored in the memory to execute the aforementioned method.

[0153] According to a fourth aspect of an embodiment of the present invention, a computer-readable storage medium is provided, on which computer program instructions are stored. When the computer program instructions are executed by a processor, the method described above is implemented.

[0154] The present invention may be a method, an apparatus, a system and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for executing various aspects of the present invention.

[0155] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for evaluating the energy absorption of a sandwich structure battery pack bottom guard plate based on strain energy analysis, characterized in that: include: Prepare a sandwich structure power battery pack bottom guard plate with an upper composite material skin, a foam core material, an embedded steel plate and a lower composite material skin stacked in sequence; Determining a stress tensor and a strain tensor of the composite material skin based on an orthotropic constitutive relationship, and calculating a strain state and a unit volume strain energy of the composite material skin according to the stress tensor and the strain tensor; Determining the principal elongation of the foam core material according to the strain state of the composite skin, substituting the principal elongation into the hyperelastic constitutive equation, and calculating the unit volume strain energy of the foam core material based on the stiffness coefficient and exponential coefficient of the foam core material; Determining the yield stress of the embedded steel plate based on the deformation state of the composite skin and the foam core, and obtaining the unit volume strain energy of the embedded steel plate by integrating the yield stress from zero to the plastic strain; Calculating the contact radius of the steel ball after impact deformation based on the Hertz contact theory formula, and determining the volume of the local deformation area according to the contact radius; The unit volume strain energies of the upper composite skin, foam core, embedded steel plate and lower composite skin are superimposed and integrated within the volume of the local deformation area to obtain the total absorbed energy. The total absorbed energy is compared with the preset impact energy. Under the conditions of meeting the energy absorption requirements and deformation constraints, the gradient optimization method is used to determine the optimal structural parameters that minimize the weight of the sandwich structure power battery pack bottom guard plate.

2. The method according to claim 1, characterized in that Determining the stress tensor and strain tensor of the composite material skin based on the orthotropic constitutive relationship, and calculating the strain state and unit volume strain energy of the composite material skin according to the stress tensor and the strain tensor includes: Obtaining a longitudinal elastic modulus, a transverse elastic modulus, and a main Poisson's ratio of the composite material skin, and generating a sixth-order stiffness matrix based on an orthotropic constitutive relationship between the longitudinal elastic modulus and the transverse elastic modulus and a coupling term between the main Poisson's ratio and the elastic modulus; measuring a three-dimensional displacement field of the composite skin under an external load, taking partial derivatives of the three-dimensional displacement field along the X-axis, the Y-axis, and the Z-axis to obtain normal strain, taking mixed partial derivatives along the XY plane, the YZ plane, and the XZ plane to obtain shear strain, and combining the normal strain and the shear strain into a strain tensor; extracting interlaminar shear deformation and bending deformation values ​​of the composite skin based on the strain tensor, and determining the strain state of the composite skin; A matrix multiplication operation is performed on the strain tensor and the sixth-order stiffness matrix to obtain a stress tensor, and the stress tensor is divided by two and multiplied with the strain tensor to obtain the unit volume strain energy of the composite skin.

3. The method according to claim 1, characterized in that The principal elongation of the foam core is determined according to the strain state of the composite skin, the principal elongation is substituted into the hyperelastic constitutive equation, and the unit volume strain energy of the foam core is calculated based on the stiffness coefficient and exponential coefficient of the foam core, including: Obtaining the stiffness coefficient and exponential coefficient of the foam core material; determining the first principal elongation, the second principal elongation, and the third principal elongation of the foam core material according to the strain state of the composite skin; substituting the first principal elongation, the second principal elongation, and the third principal elongation into the strain energy density equation, which is: ； in, U foam is the unit volume strain energy of the foam core material, i is the item number, N is the total number of items, μ i is the stiffness coefficient of the foam core material, α i is the exponential coefficient of the foam core material, λ 1 is the first principal elongation, λ 2 is the second principal elongation, λ 3 is the third principal elongation.

4. The method according to claim 1, wherein Determining the yield stress of the embedded steel plate based on the deformation state of the composite skin and the foam core, and integrating the yield stress from zero to the plastic strain to obtain the unit volume strain energy of the embedded steel plate includes: The yield stress and plastic strain of the embedded steel plate are determined according to the deformation state of the composite skin and the foam core material. The yield stress and plastic strain are substituted into the strain energy formula of the embedded steel plate to calculate the unit volume strain energy of the embedded steel plate. The strain energy formula of the embedded steel plate is: ； in, U steel is the unit volume strain energy of the embedded steel plate, σ y is the yield stress of the embedded steel plate, ε p is the plastic strain of the embedded steel plate, ε is the strain variable.

5. The method according to claim 1, wherein Calculating the contact radius of the steel ball after impact deformation based on the Hertz contact theory formula, and determining the volume of the local deformation area according to the contact radius includes: Obtain the contact radius of the steel ball impact test, and substitute the contact radius into the Hertz contact theory formula to calculate the volume of the local deformation area caused by the impact deformation of the steel ball under impact test. The Hertz contact theory formula is: ； in, V impact is the volume of the local deformation area, R impact is the contact radius after impact deformation, and π is the pi.

6. The method according to claim 1, characterized in that The total absorbed energy is compared with the preset impact energy. Under the conditions of meeting the energy absorption requirements and deformation constraints, the optimal structural parameters for minimizing the weight of the sandwich structure power battery pack bottom guard plate are determined using a gradient optimization method, including: Calculating the total weight of the sandwich structure power battery pack bottom guard plate by summing the product of the density and thickness of the upper composite material skin, the product of the density and thickness of the foam core material, the product of the density and thickness of the embedded steel plate, and the product of the density and thickness of the lower composite material skin; Comparing the total absorbed energy with a preset energy absorption threshold of the sandwich structure power battery pack bottom guard plate to obtain a first judgment result, and comparing the maximum deformation of the sandwich structure power battery pack bottom guard plate with a critical deformation of the sandwich structure power battery pack bottom guard plate to obtain a second judgment result; determining an optimization objective function according to the first judgment result and the second judgment result, and setting the total weight as the optimization objective function when the total absorbed energy is greater than the preset energy absorption threshold and the maximum deformation is less than the critical deformation; Based on the gradient information of the optimization objective function, the optimization parameters of the thickness of the upper composite skin, the density and thickness of the foam core material, the thickness of the embedded steel plate and the thickness of the lower composite skin are iteratively updated until the optimization objective function converges to a minimum value, thereby obtaining the optimal structural parameters of the sandwich-structured power battery pack bottom guard plate.

7. The sandwich structure battery pack bottom guard plate energy absorption assessment system based on strain energy analysis is characterized by: Used to implement the method according to any one of claims 1 to 6.

8. An electronic device, characterized in that: include: processor; a memory for storing processor-executable instructions; The processor is configured to call the instructions stored in the memory to execute the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having computer program instructions stored thereon, characterized in that: When the computer program instructions are executed by a processor, the method according to any one of claims 1 to 6 is implemented.

Images