Battery box structure optimization design method based on finite element method

Abstract

The invention relates to the technical field of battery design, and particularly discloses a battery box structure optimization design method based on a finite element method. The method comprises the following steps that modeling is conducted on the battery box according to design data of the battery box, finite element analysis is conducted, the anti-vibration strength of a box bottom plate is obtained, and if the anti-vibration strength of the box bottom plate does not meet the design requirement, structural optimization and / or material optimization are / is conducted on the box bottom plate, the design data are updated, and then the method returns to the initial step; if the anti-vibration strength of the box bottom plate meets the design requirement, the relation between the proportion of the weight of the box body to the total weight of the battery box and a preset value is judged, and if the anti-vibration strength is larger than or equal to the preset value, structural optimization and / or material optimization are / is conducted on the battery box, design data are updated, and then the initial step is executed. According to the method, a systematized solution is formed, so that the overall weight of the battery box is reduced to the greatest extent on the premise of ensuring the vibration safety.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery design, and particularly relates to a battery box structure optimization design method based on a finite element method. BACKGROUND

[0002] With the rapid development of electric aircraft and various types of unmanned aerial vehicles, the airborne power battery system has become one of the core components affecting the flight performance. As a key unit for energy storage and power supply, the battery box not only needs to have high energy density and high safety, but also needs to maintain structural integrity in a harsh vibration environment. At present, the box welding assembly of the airborne lithium battery box is usually designed by using a traditional steel structure or an aluminum structure, and the battery module is usually mechanically connected to the battery module beam in the box through long bolts. Although this type of structure has certain advantages in terms of vibration resistance and strength, it has a large self-weight, which seriously restricts the endurance of the aircraft. Under the increasingly complex air working conditions, the large structure weight leads to an increase in the flight resistance of the fuselage and an increase in energy consumption, thereby limiting the flight time and operating radius. Therefore, lightweight design has become a key breakthrough for improving the comprehensive performance of the airborne power supply system.

[0003] To meet the dual targets of high vibration resistance and lightweight, the traditional design usually adopts the following methods: increasing the thickness of local components, replacing the metal material with a higher strength metal material, adding a battery module beam, or adding a battery module connecting piece connected to the side wall of the box. However, these methods further increase the self-weight of the box, especially for the aviation power battery system which is extremely sensitive to weight. In the process of each take-off, maneuvering and landing of the aircraft, the vibration and impact load borne by the battery box is extremely complex. Therefore, how to effectively reduce the weight while ensuring the structural rigidity and vibration resistance has become a technical difficulty in the industry.

[0004] The current feasible lightweight path mainly includes three types: structural topology optimization, new material replacement, and production process innovation. Among them, the lightweight benefit brought by material replacement is particularly significant. Carbon fiber reinforced composite materials are widely considered to be one of the ideal materials for realizing the weight reduction of airborne equipment because of their low density, high specific stiffness, high specific strength and good fatigue performance. However, the structural design of composite materials is essentially different from that of metal structures, and the dynamic response of composite materials in a vibration environment and the stress concentration at the connection site are more complex. If not fully simulated and analyzed and systematically optimized, direct replacement with composite materials may not meet the requirements of vibration resistance and weight reduction at the same time.

[0005] However, the traditional design process usually relies on experience design and physical test verification, with long development cycle, high cost, and difficulty in rapid evaluation and iteration of multiple design schemes. In particular, for composite material battery box structure, if there is no effective numerical simulation means, it is easy to cause vibration exceeding the standard due to insufficient local stiffness, or weight redundancy due to excessive design.

[0006] In summary, the existing airborne battery box structure design has not yet formed a systematic solution to the challenges of high vibration resistance and lightweight. SUMMARY

[0007] The purpose of the present application is to provide a battery box structure optimization design method based on the finite element method, to minimize the overall weight while ensuring vibration safety.

[0008] To achieve this purpose, the present application adopts the following technical solutions:

[0009] The battery box structure optimization design method based on the finite element method, the battery box includes a box body and a battery module, the battery module is contained in the box body, the box body includes a bottom plate, the battery box structure optimization design method based on the finite element method includes the following steps:

[0010] S10: modeling the battery box according to the design data of the battery box and performing finite element analysis to obtain the vibration resistance strength of the bottom plate, if the vibration resistance strength of the bottom plate does not meet the design requirements, S20 is executed, if the vibration resistance strength of the bottom plate meets the design requirements, S30 is executed;

[0011] S20: structure optimization and / or material optimization of the bottom plate, update the design data and return to S10;

[0012] S30: determine the relationship between the proportion of the weight of the box body in the total weight of the battery box and the preset value, if greater than or equal to the preset value, structure optimization and / or material optimization of the battery box, update the design data and return to S10.

[0013] As an optional technical solution of the battery box structure optimization design method based on the finite element method, in the S10, the vibration resistance strength is characterized by 1σ stress, the 1σ stress of the bottom plate obtained by finite element analysis is defined as M, the A% tensile strength of the material used for the bottom plate is defined as N, A is greater than 0 and less than 100, if M is less than N, it is determined that the vibration resistance strength of the bottom plate meets the design requirements, if M is greater than or equal to N, it is determined that the vibration resistance strength of the bottom plate does not meet the design requirements.

[0014] As an optional technical solution of the battery box structure optimization design method based on the finite element method, A is 18 to 22.

[0015] As an optional technical solution for the battery box structure optimization design method based on the finite element method, the step of determining the relationship between the weight of the box body and the total weight of the battery box and a preset value includes the following steps: determining whether the sum of the weights of the components other than the battery module accounts for a percentage of the total weight of the battery box that is less than B, where B is 3 to 7; if not, then determining that the weight of the box body accounts for a percentage of the total weight of the battery box that is greater than or equal to the preset value.

[0016] As an optional technical solution for the battery box structure optimization design method based on the finite element method, the structural optimization of the box bottom plate in S20 includes the following steps: adjusting the thickness of the box bottom plate.

[0017] As an optional technical solution for the battery box structure optimization design method based on the finite element method, the structural optimization of the battery box in S30 includes the following steps: adjusting the thickness of the box bottom plate; and / or, optimizing the structure of the beam provided on the box bottom plate.

[0018] As an optional technical solution for the battery box structure optimization design method based on the finite element method, the beam structure includes longitudinal reinforcing beams, transverse reinforcing beams, and / or partition reinforcing beams. The longitudinal reinforcing beams are located at the edge of the box bottom plate and extend along the length direction of the battery box. The transverse reinforcing beams are located at the edge of the box bottom plate and extend along the width direction of the battery box. The partition reinforcing beams are located between two adjacent battery modules. The structural optimization of the beam structure located on the box bottom plate includes the following steps: adding or removing the longitudinal reinforcing beams on the box bottom plate; and / or adding or removing the transverse reinforcing beams on the box bottom plate; and / or adding or removing the partition reinforcing beams on the box bottom plate.

[0019] As an optional technical solution for the battery box structure optimization design method based on the finite element method, the two ends of the longitudinal reinforcing beam cross-section are respectively attached to the upper surface of the box bottom plate, and the middle part of the longitudinal reinforcing beam cross-section is spaced apart from the box bottom plate; and / or, the cross-section of the transverse reinforcing beam is I-shaped, and the bottom surface of the transverse reinforcing beam is attached to the upper surface of the box bottom plate; and / or, the cross-section of the partition reinforcing beam is L-shaped, and the horizontal plate of the partition reinforcing beam is attached to the upper surface of the box bottom plate.

[0020] As an optional technical solution for the battery box structure optimization design method based on the finite element method, the bottom plate of the box is made of aluminum alloy, and the components other than the bottom plate and the beam structure are made of carbon fiber.

[0021] As an optional technical solution of the battery box structure optimization design method based on the finite element method, the modeling of the battery box according to the design data of the battery box and the finite element analysis include the following steps: importing the three-dimensional data of the battery box into the finite element numerical simulation software, creating a boundary condition, and applying a working condition load.

[0022] The battery box applied to the battery box structure optimization design method based on the finite element method includes a box body and a battery module, the battery module is accommodated in the box body, and the box body includes a box bottom plate for bearing the battery module, and a beam structure is arranged on the box bottom plate.

[0023] The beneficial effects of the present application are:

[0024] The battery box structure optimization design method based on the finite element method ensures that the vibration resistance strength of the box bottom plate meets the design requirements through iterative optimization, and controls the proportion of the weight of the box body. The method effectively solves the balance problem between lightweight and high vibration resistance of the traditional battery box; through finite element analysis, the risk of structural failure of the box bottom plate due to insufficient vibration resistance strength in the vibration environment is avoided, and after meeting the vibration resistance requirements, the proportion of the weight of the box body in the total weight is further controlled to prevent overdesign, thereby realizing the extreme lightweight of the battery box. The above method realizes efficient design and verification of the battery box structure through iterative optimization, realizes extreme weight reduction while ensuring high vibration resistance, and is particularly suitable for weight-sensitive scenes such as airborne power batteries with strict weight indicators, prolonging the endurance mileage of the airborne power supply. In addition, by replacing part of the physical test with finite element numerical simulation, the design cycle is significantly shortened, and the cost of physical test is reduced.

[0025] The battery box is designed and manufactured by the battery box structure optimization design method based on the finite element method. Through the foregoing finite element numerical simulation optimization iteration process, the high vibration resistance requirements of the box bottom plate and the beam structure are ensured, and the extreme lightweight is realized. Its structure is the final form verified and optimized scientifically, and has reliable structural strength and minimum weight proportion. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a flowchart of the battery box structure optimization design method based on the finite element method provided by the embodiment of the present application;

[0027] Figure 2 is a structural schematic diagram of the battery box provided by the embodiment of the present application;

[0028] Figure 3 is an exploded view of the battery box provided by the embodiment of the present application;

[0029] Figure 4 is a cross-sectional view of the battery box provided by the embodiment of the present application;

[0030] Figure 5 is Figure 4 A is a partial enlarged view of the middle part of A.

[0031] In the figure:

[0032] 100, battery module; 200, bottom plate of the box; 300, beam structure; 310, longitudinal reinforcing beam; 320, transverse reinforcing beam; 330, partition reinforcing beam; 400, box shell; 500, foam pad; 600, box cover; 700, fixed edge; 800, rivet. DETAILED DESCRIPTION

[0033] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0034] In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", etc. are only for the purpose of description, and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions, and moreover, the "above", "above" and "above" of the first feature to the second feature include the first feature above and obliquely above the second feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The "below", "below" and "below" of the first feature to the second feature include the first feature below and obliquely below the second feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0035] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0036] Embodiments of the present application are described in detail below with reference to the attached drawing figures, wherein the same or like component have the same or similar designations. The embodiments described below are exemplary and are not intended to be limiting of the present application, unless otherwise explicitly indicated herein.

[0037] Figure 1 A flowchart of the battery box structure optimization design method based on the finite element method provided by the present application, Figures 2 to 5 A schematic diagram of the battery box provided by the present application, the battery box comprises a box body and a battery module 100, the battery module 100 is accommodated in the box body, the box body comprises a box bottom plate 200, the battery box structure optimization design method based on the finite element method comprises the following steps:

[0038] S10: modeling the battery box according to the design data of the battery box, and performing finite element analysis to obtain the vibration resistance strength of the box bottom plate 200, if the vibration resistance strength of the box bottom plate 200 does not meet the design requirement, performing S20, if the vibration resistance strength of the box bottom plate 200 meets the design requirement, performing S30.

[0039] S20: performing structure optimization and / or material optimization on the box bottom plate 200, returning to S10 after updating the design data.

[0040] S30: judging the relationship between the proportion of the weight of the box body in the total weight of the battery box and the preset value, if greater than or equal to the preset value, performing structure optimization and / or material optimization on the battery box, returning to S10 after updating the design data.

[0041] In S30, if the proportion of the weight of the box body in the total weight of the battery box is less than the preset value, the following steps are performed:

[0042] S40: ending the finite element analysis, determining that the structure optimization design of the battery box is completed.

[0043] The battery box structure optimization design method based on the finite element method ensures that the vibration resistance strength of the box bottom plate 200 meets the design requirements through iterative optimization, while controlling the proportion of the box weight in the total weight. The method effectively solves the balance problem between lightweight and high vibration resistance of the traditional battery box; through finite element analysis, the risk of structural failure of the box bottom plate 200 due to insufficient vibration resistance strength in the vibration environment is avoided, and after meeting the vibration resistance requirements, the proportion of the box weight in the total weight is further controlled to prevent overdesign, thereby realizing the ultimate lightweight of the battery box. The above method realizes efficient design and verification of the battery box structure through iterative optimization, while ensuring high vibration resistance and achieving ultimate weight reduction, especially suitable for weight-sensitive scenarios such as airborne power batteries with strict weight indicators, prolonging the endurance mileage of airborne power sources. In addition, by replacing part of the physical test with finite element numerical simulation, the design cycle is significantly shortened, and the cost of physical testing is reduced.

[0044] In the prior art, lithium batteries are increasingly widely used as power systems in the field of electric vertical take-off and landing aircraft. With the gradual improvement of the standard system in the aviation field, the requirements for thermal management, lightweight, and high vibration resistance of the power system are inevitably higher. Under the premise of considering thermal management and high vibration resistance, the battery box structure optimization design method based on the finite element method starts from the design of the battery box structure and proposes a lightweight design and finite element numerical simulation optimization method with great application value. On the one hand, the scheme can meet the heat dissipation requirements, and on the other hand, it can greatly reduce the self-weight of the battery box, and can also meet the high vibration resistance working condition scenario, which has great application and promotion value.

[0045] In the embodiment, the box body further includes a box cover 600, a foam pad 500, a box shell 400, a fixing edge 700, and a rivet 800. The top end of the box shell 400 is connected with the box cover 600, and the bottom end is connected with the box bottom plate 200. All battery modules 100 are placed in the space surrounded by the box shell 400, the box cover 600, and the box bottom plate 200. The box cover 600 plays a role in dust prevention and space sealing. The box shell 400 is provided with light-weight electrical components. The box bottom plate 200 supports the weight of the battery modules 100 and also plays a role in heat conduction. The foam pad 500 is arranged between the battery modules 100 and the box cover 600, which plays a role in restraining the local degrees of freedom of the battery modules 100 and buffering, avoiding the left and right shaking of the battery modules 100 during vibration, and buffering the interaction between the battery modules 100 and the box cover 600, avoiding the use of connecting pieces on the battery modules 100 connected to the side wall of the box shell 400. The fixing edge 700 is used for installing and fixing the entire battery box and belongs to a whole load-bearing structure. The box shell 400, the box bottom plate 200, and the fixing edge 700 are connected through the rivet 800. The above-mentioned box components adopt a split design, which can simplify the structure of the box, reduce the difficulty of production and manufacturing, and reduce costs under the premise of meeting the strength requirements.

[0046] The battery box is designed and manufactured by using the battery box structure optimization design method based on the finite element method. Through the foregoing finite element numerical simulation optimization iteration process, the high vibration resistance requirement of the box bottom plate 200 and the beam structure 300 is ensured, and the extreme lightweight is realized. The structure is the final form verified and optimized by science, and has reliable structure strength and minimum weight ratio.

[0047] Further, the bottom of the battery module 100 is connected with the box bottom plate 200 by structural adhesive, and the foam pad 500 is connected with the box cover 600 by structural adhesive, thereby reducing the total weight of the box and the production cost.

[0048] As a main component for resisting vibration, the box bottom plate 200 is verified for vibration resistance strength based on the battery box structure optimization design method based on the finite element method. However, in view of the requirement for improving the safety factor of the battery box structure, it is necessary to detect the vibration resistance strength of the components in the battery box except the battery module 100, so as to ensure the optimization of the overall design of the battery box.

[0049] For example, the components in the battery box except the battery module 100 need to obtain the corresponding vibration resistance strength. If the vibration resistance strength does not meet the design requirement, the component needs to be optimized in structure and / or material. If the vibration resistance strength meets the design requirement, there is no need to optimize the structure and / or material. After all the components except the battery module 100 meet the design requirement, S30 is executed. Accordingly, the optimization design of all the components except the battery module 100 is realized by the finite element numerical simulation optimization method, which ensures the vibration resistance strength of the overall battery box and realizes further weight reduction design.

[0050] In this embodiment, in S10, the vibration resistance strength is characterized by 1σ stress, the 1σ stress of the box bottom plate 200 obtained by the finite element analysis is defined as M, and the A% tensile strength of the material used for the box bottom plate 200 is defined as N, A is greater than 0 and less than 100. If M is less than N, it is determined that the vibration resistance strength of the box bottom plate 200 meets the design requirement. If M is greater than or equal to N, it is determined that the vibration resistance strength of the box bottom plate 200 does not meet the design requirement.

[0051] The above design explicitly quantitatively evaluates the anti-vibration strength of the box bottom plate 200 by comparing the percentage of 1σ stress and the tensile strength of the material, providing a quantitative failure judgment basis, ensuring that the box bottom plate 200 has sufficient safety margin under vibration load. This evaluation method based on the relationship between stress and strength ensures the structural reliability of the box bottom plate 200 in the vibration environment, prevents failure due to stress concentration, avoids overdesign or underdesign, and thus ensures lightweight under the premise of high vibration resistance. It enables designers to quickly identify weak areas and conduct targeted optimization, making the optimization process more scientific and accurate, and improving the safety and durability of the battery box under airborne vibration conditions.

[0052] Further, A is 18 to 22. Specifically, A is 20.

[0053] By limiting the A% of tensile strength within a reasonable range, the safety margin of the box bottom plate 200 is ensured while avoiding excessive weight increase due to excessive conservatism. This range is based on material mechanical properties and actual working conditions, balancing structural strength and lightweight requirements, ensuring that the battery box still meets high vibration resistance standards under the premise of lightweight, maximizing material utilization, preventing weight increase due to excessive safety factor, and avoiding vibration failure due to low factor, thereby optimizing the overall performance of the battery box.

[0054] In the present embodiment, judging the relationship between the proportion of the box body weight in the total weight of the battery box and the preset value includes the following steps: judging whether the sum of the weights of the components other than the battery module 100 accounts for less than B% of the total weight of the battery box, and if not, determining that the proportion of the box body weight in the total weight of the battery box is greater than or equal to the preset value.

[0055] By judging whether the proportion of the box body weight in the total weight of the battery box exceeds the preset value, the optimization is directly aimed at the lightweight target, ensuring the effectiveness of the lightweight design. This encourages designers to continuously optimize the box body structure, thereby directly improving the energy density and flight endurance of the battery box, extending the endurance of airborne equipment, and reducing production costs.

[0056] Further, B is 3 to 7. Specifically, B is 5.

[0057] This threshold is based on the actual weight distribution of the battery box and the lightweight target. It ensures that the box body weight is strictly controlled at a low level, avoiding the parts other than the battery module 100 from becoming a weight burden, while allowing necessary structural reinforcement, achieving an optimal balance between lightweight and structural strength, and significantly improving energy density and flight endurance.

[0058] In the present embodiment, the structural optimization of the box bottom plate 200 in S20 includes the following steps: adjusting the thickness of the box bottom plate 200.

[0059] By adjusting the thickness of the box bottom plate 200 and changing the material, the anti-vibration strength is flexibly enhanced and the weight is reduced, and the structural performance is quickly improved. These methods are simple and easy to implement, and can quickly improve the stiffness and strength of the box bottom plate 200, ensure that the anti-vibration requirements are met, and highlight the effectiveness of thickness optimization.

[0060] Exemplarily, the structural optimization of the box bottom plate 200 in S30 includes the following steps: adjusting the thickness of the box bottom plate 200, and structurally optimizing the beam structure 300 arranged on the box bottom plate 200.

[0061] The above limitations when the weight ratio is too high provide a variety of optimization options, including adjusting the thickness of the box bottom plate 200 and optimizing the beam structure 300, thereby allowing the designer to flexibly trade off between lightweight and anti-vibration. By optimizing the beam structure 300 instead of simply increasing the thickness of the box bottom plate 200 to meet the requirements, the weight increase is minimized while ensuring the stiffness of the box bottom plate 200. The above method significantly improves the design freedom, minimizes the total weight while ensuring the anti-vibration, and simplifies the production process. This avoids the weight increase caused by simply increasing the thickness, and optimizes the structural efficiency.

[0062] In another embodiment of the present embodiment, the structural optimization of the battery box in S30 includes the following steps: adjusting the thickness of the box bottom plate 200. In yet another embodiment of the present embodiment, the structural optimization of the box bottom plate 200 in S30 includes the following steps: structurally optimizing the beam structure 300 arranged on the box bottom plate 200.

[0063] Further, the beam structure 300 includes a longitudinal reinforcing beam 310, a transverse reinforcing beam 320, and / or a partition reinforcing beam 330, the longitudinal reinforcing beam 310 is arranged at the edge of the box bottom plate 200 and extends along the length direction of the battery box, the transverse reinforcing beam 320 is arranged at the edge of the box bottom plate 200 and extends along the width direction of the battery box, and the partition reinforcing beam 330 is arranged between two adjacent battery modules 100; the structural optimization of the beam structure 300 arranged on the box bottom plate 200 includes the following steps: increasing or decreasing the longitudinal reinforcing beam 310 on the box bottom plate 200; and / or, increasing or decreasing the transverse reinforcing beam 320 on the box bottom plate 200; and / or, increasing or decreasing the partition reinforcing beam 330 on the box bottom plate 200.

[0064] By selectively adding or reducing the corresponding beam structure 300, the different stress areas of the battery box are locally reinforced, realizing high vibration resistance without unnecessary weight increase, and refining the optimization strategy of the beam structure 300. The longitudinal reinforcing beam 310 and the transverse reinforcing beam 320 enhance the edge support of the box bottom plate 200; the partition reinforcing beam 330 reduces the vibration interference between the battery modules 100. These designs enhance the overall stiffness and vibration resistance of the box bottom plate 200, especially between the battery modules 100 and the edge area, ensuring the stability of the battery modules 100 in a vibrating environment. By selectively determining whether to add or reduce these reinforcing beams, the optimization process can avoid unnecessary beam structures 300, reduce the stress of the battery box bottom, minimize weight increase, reduce production costs, meet vibration standards and safety thresholds, realize targeted structural reinforcement, and ensure the accuracy and efficiency of structural optimization.

[0065] In one embodiment of the present embodiment, the two ends of the cross section of the longitudinal reinforcing beam 310 are respectively fitted with the upper plate surface of the box bottom plate 200, and the middle part of the cross section of the longitudinal reinforcing beam 310 is arranged spaced apart from the box bottom plate 200; and the cross section of the transverse reinforcing beam 320 is in the shape of a straight line, and the bottom surface of the transverse reinforcing beam 320 is fitted with the upper plate surface of the box bottom plate 200; and the cross section of the partition reinforcing beam 330 is in the shape of an L letter, and the horizontal plate of the partition reinforcing beam 330 is fitted with the upper plate surface of the box bottom plate 200.

[0066] By defining the specific shape and connection method of each reinforcing beam, the stress distribution is optimized, the carrying efficiency of the beam is improved, the structural stability and force transmission efficiency are ensured, and the unification of high strength and light weight is realized. The specific structural design of the cross section of the longitudinal reinforcing beam 310 provides high bending stiffness, the straight-line transverse reinforcing beam 320 enhances the transverse support, and the L-shaped partition reinforcing beam 330 effectively isolates the battery modules 100 and reduces vibration transmission. These beam structures 300 are welded and riveted with the box bottom plate 200 to ensure firm combination and enhance the overall structural integrity, further improving the vibration resistance performance. At the same time, the fitting design reduces stress concentration, improves the support capacity of the box bottom plate 200, prolongs the service life of the components, and ensures the structural integrity on the basis of light weight.

[0067] Specifically, the beam structure 300 is connected with the box bottom plate 200 by resistance welding, and the lap joint of the beam structure 300 is connected by argon arc welding. The above-mentioned connection method of the reinforcing beam on the box bottom plate 200 ensures the overall structural integrity, and helps to improve the heat conduction efficiency of the box bottom plate 200.

[0068] In other embodiments of the present embodiment, only two ends of the cross section of the longitudinal reinforcing beam 310 are respectively fitted with the upper plate surface of the box bottom plate 200, and the middle part of the cross section of the longitudinal reinforcing beam 310 is arranged spaced apart from the box bottom plate 200; the cross section of the transverse reinforcing beam 320 is in the shape of a straight line, and the bottom surface of the transverse reinforcing beam 320 is fitted with the upper plate surface of the box bottom plate 200; and at most two of the transverse plate of the partition reinforcing beam 330 and the upper plate surface of the box bottom plate 200 are fitted.

[0069] Further, the middle part of the box bottom plate 200 is concavely arranged downward with a receiving groove, one end of the longitudinal reinforcing beam 310 is in contact with the edge of the box bottom plate 200, and the other end is in contact with the groove bottom of the receiving groove; the transverse reinforcing beam 320 is in contact with the edge of the box bottom plate 200; and the partition reinforcing beam 330 is in contact with the groove bottom of the receiving groove.

[0070] The design of the receiving groove optimizes the layout and heat dissipation path of the battery module 100, and improves the space utilization. The longitudinal reinforcing beam 310 is in contact with the groove bottom of the receiving groove, enhancing the continuity of the overall structure; the transverse reinforcing beam 320 is in contact with the edge of the box bottom plate 200, providing peripheral support; and the partition reinforcing beam 330 is in contact with the groove bottom of the receiving groove, ensuring the fixation of the battery module 100. This arrangement not only improves the carrying capacity of the battery box, but also promotes heat management, as the receiving groove helps air convection and heat conduction, thereby improving heat dissipation efficiency, meeting the needs of airborne battery boxes for compact structure and efficient heat management.

[0071] In the present embodiment, the thicknesses of the longitudinal reinforcing beam 310, the transverse reinforcing beam 320 and the partition reinforcing beam 330 are all the same. Specifically, the thicknesses of the longitudinal reinforcing beam 310, the transverse reinforcing beam 320 and the partition reinforcing beam 330 are all 1.5 millimeters.

[0072] By unifying the thickness of the beam structure 300, the manufacturing process and material procurement of the beam structure 300 are simplified, and the production cost is reduced. The same thickness ensures the consistency of the beam structure 300 during welding and connection, reduces stress concentration points, and improves structural reliability. This standardized design ensures anti-vibration performance while avoiding weight increase caused by uneven thickness, further optimizing lightweight effect, and is suitable for mass production.

[0073] Exemplarily, the materials of the components other than the box bottom plate 200 and the beam structure 300 are the same.

[0074] By using a unified material, the overall weight is significantly reduced and the structure is simplified. The unified material also simplifies the material property assignment in the finite element model, improves the simulation accuracy, and ensures the reliability of the optimization process, so as to meet the high anti-vibration requirements while achieving the ultimate lightweight design.

[0075] In the embodiment, the box bottom plate 200 is made of aluminum alloy material, and the components other than the box bottom plate 200 and the beam structure 300 are made of carbon fiber material.

[0076] The box bottom plate 200 made of aluminum alloy material can efficiently conduct heat as a heat dissipation interface, and can rely on air convection during flight to cool the battery box during discharging, and can cool or heat the battery according to specific use conditions during charging. Thus, heat dissipation and strength are taken into account, and efficient thermal management is achieved. The carbon fiber structure greatly reduces the weight of the components other than the box bottom plate 200 and the beam structure 300, which is extremely beneficial to use scenarios with strict weight requirements. The above material combination ensures heat dissipation efficiency while reducing the overall weight of the battery box, solves the problem of poor heat dissipation of the sealed carbon fiber battery box, and improves the endurance of the airborne battery.

[0077] Specifically, the thickness of the box cover 600 and the box shell 400 is 1 mm, and the thickness of the fixed edge 700 is 3 mm.

[0078] In the embodiment, the battery box is modeled according to the design data of the battery box, and finite element analysis is performed including the following steps: importing the three-dimensional data of the battery box into the finite element numerical simulation software, dividing the grid, assigning material properties, creating boundary conditions, applying working conditions load, submitting operation, and viewing simulation analysis results. The data processed by the above steps are simulated and analyzed, and the simulation analysis results are viewed, so as to obtain the vibration resistance of the box bottom plate 200.

[0079] The above steps specify the specific process of finite element modeling. By importing three-dimensional data, setting boundary conditions and applying working condition load, the accuracy and reliability of finite element analysis are ensured, and the simulation results can effectively simulate the behavior of the battery box in the actual vibration environment. Through this method, designers can quickly verify multiple schemes, identify stress distribution and failure risk, and thus discover and solve potential problems before physical manufacturing, and guide optimization design through simulation results, thereby improving design efficiency and reducing development cost. The above steps greatly shorten the development cycle, reduce the cost of physical testing, and ensure the high vibration resistance and lightweight performance of the battery box in the complex environment of the airborne.

[0080] Further, the working condition load is performed according to the test method specified in RTCA / DO-160G.

[0081] The battery box is verified whether it meets the RTCA / DO-160G Chapter 8: Vibration G curve of the airborne equipment environmental conditions and test procedures by using the finite element numerical simulation optimization method, and the total root mean square acceleration of the curve is 2.75 Grms. Therefore, it is ensured that the finite element optimization process is consistent with the real airborne environment, and the vibration resistance performance of the battery box under the aviation standard is verified. By applying the standard, the method can simulate the vibration conditions in the actual flight, the optimization result is more reliable and practical, the test cycle is shortened, the certification cost is reduced, and thus the industrialization application of the battery box in the aviation field is accelerated.

[0082] Next, taking the battery box with the initial design of the thickness of the box bottom plate 200 being 1.5 mm and the thickness of the partitioned reinforcing beam 330 arranged on the box bottom plate 200 being 1.5 mm as an example, the battery box structure optimization design method based on the finite element method is performed. After the finite element analysis, the maximum 1σ stress of the carbon fiber material of the box cover 600, the box shell 400 and the fixed edge 700 is 95.67 MPa, which is far less than the safety threshold 680 MPa of the carbon fiber material; the 1σ stress of the box bottom plate 200 and the beam structure 300 is 78.272 MPa, which exceeds the safety threshold 52 MPa of the aluminum alloy material.

[0083] Therefore, the thickness of the box bottom plate 200 needs to be optimized and changed to 3 mm. After the finite element analysis, the maximum 1σ stress of the carbon fiber material of the box cover 600, the box shell 400 and the fixed edge 700 is 110.6 MPa, which is far less than the safety threshold 680 MPa of the carbon fiber material; the 1σ stress of the box bottom plate 200 and the beam structure 300 is 35.424 MPa, which does not exceed the safety threshold 52 MPa of the aluminum alloy material, but the total weight of the box body increases by 1 kg, so that the proportion of the weight of the box body in the total weight of the battery box is greater than the preset value.

[0084] Therefore, the battery box needs to be optimized and designed, the thickness of the box bottom plate 200 is changed to 1.5 mm, and the longitudinal reinforcing beam 310 and the transverse reinforcing beam 320 with a thickness of 1.5 mm are added to the box bottom plate 200. After the finite element analysis, the maximum 1σ stress of the carbon fiber material of the box cover 600, the box shell 400 and the fixed edge 700 is 99.16 MPa, which is far less than the safety threshold 680 MPa of the carbon fiber material; the 1σ stress of the box bottom plate 200 and the beam structure 300 is 46.186 MPa, which does not exceed the safety threshold 52 MPa of the aluminum alloy material; the total weight of the box body increases by 0.265 kg, and the proportion of the weight of the box body in the total weight of the battery box is less than the preset value. At this time, the finite element analysis is ended, and it is determined that the structure optimization design of the battery box is completed.

[0085] In other embodiments of the above examples, the box bottom plate 200 can also be optimized by changing the material of the box bottom plate 200, so as to change the 1σ stress of the box bottom plate 200 and the tensile strength of the material used by the box bottom plate 200. Specifically, the box bottom plate 200 applied as a heat dissipation interface can be made of aluminum alloy, aluminum silicon carbide, or thermally conductive plastic, etc.

[0086] Obviously, the above embodiments of the present application are merely examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. Based on the above description, other different forms of changes or variations can also be made by those of ordinary skill in the art. Here, it is not necessary and also impossible to exhaust all the embodiments. Any modification, equivalent replacement, and improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A battery case structure optimization design method based on a finite element method, the battery case comprising a case body and a battery module (100), the battery module (100) being accommodated in the case body, the case body comprising a case bottom plate (200), characterized in that, The battery box structure optimization design method based on the finite element method comprises the following steps: S10: modeling the battery box according to the design data of the battery box and performing finite element analysis to obtain the vibration resistance strength of the bottom plate (200), if the vibration resistance strength of the bottom plate (200) does not meet the design requirement, S20 is executed, if the vibration resistance strength of the bottom plate (200) meets the design requirement, S30 is executed; S20: structure optimization and / or material optimization of the bottom plate (200), and returning to S10 after updating the design data; S30: judging the relationship between the proportion of the weight of the box in the total weight of the battery box and the preset value, if greater than or equal to the preset value, structure optimization and / or material optimization of the battery box is performed, and returning to S10 after updating the design data.

2. The battery case structure optimization design method based on the finite element method according to claim 1, characterized by, In S10, the vibration resistance strength is represented by 1σ stress, the 1σ stress of the bottom plate (200) obtained by finite element analysis is defined as M, the A% tensile strength of the material used for the bottom plate (200) is defined as N, A is greater than 0 and less than 100, if M is less than N, it is determined that the vibration resistance strength of the bottom plate (200) meets the design requirement, if M is greater than or equal to N, it is determined that the vibration resistance strength of the bottom plate (200) does not meet the design requirement.

3. The finite element method-based battery case structure optimization design method according to claim 2, characterized by, A is 18 to 22.

4. The finite element method-based battery case structure optimization design method of claim 1, wherein, The judgment of the relationship between the proportion of the weight of the box in the total weight of the battery box and the preset value comprises the following steps: judging whether the sum of the weights of the components other than the battery module (100) accounts for less than B% of the total weight of the battery box, B is 3 to 7, if not, it is determined that the proportion of the weight of the box in the total weight of the battery box is greater than or equal to the preset value.

5. The finite element method-based battery case structure optimization design method according to claim 1, characterized by, The structure optimization of the bottom plate (200) in S20 comprises the following steps: adjusting the thickness of the bottom plate (200).

6. The finite element method-based battery case structure optimization design method of claim 1, wherein, The structure optimization of the battery box in S30 comprises the following steps: adjusting the thickness of the bottom plate (200); and / or, structure optimization of the beam structure (300) provided on the bottom plate (200).

7. The finite element method-based battery case structure optimization design method according to claim 6, characterized by, The beam structure (300) comprises longitudinal reinforcing beams (310), transverse reinforcing beams (320) and / or partition reinforcing beams (330), the longitudinal reinforcing beams (310) are provided on the edges of the bottom plate (200) and extend along the length direction of the battery box, the transverse reinforcing beams (320) are provided on the edges of the bottom plate (200) and extend along the width direction of the battery box, and the partition reinforcing beams (330) are provided between two adjacent battery modules (100); the structure optimization of the beam structure (300) provided on the bottom plate (200) comprises the following steps: increasing or decreasing the longitudinal reinforcing beams (310) on the bottom plate (200); and / or, increasing or decreasing the transverse reinforcing beams (320) on the bottom plate (200); and / or, increasing or decreasing the partition reinforcing beams (330) on the bottom plate (200).

8. The finite element method-based battery case structure optimization design method according to claim 7, characterized by, Two ends of the cross section of the longitudinal reinforcing beam (310) are respectively fitted with the upper plate surface of the box bottom plate (200), and the middle part of the cross section of the longitudinal reinforcing beam (310) is spaced apart from the box bottom plate (200); and / or, The cross section of the transverse reinforcing beam (320) is in the shape of a single character, and the bottom surface of the transverse reinforcing beam (320) is fitted with the upper plate surface of the box bottom plate (200); and / or, The cross section of the partition reinforcing beam (330) is in the shape of an L character, and the horizontal plate of the partition reinforcing beam (330) is fitted with the upper plate surface of the box bottom plate (200).

9. The finite element method-based battery case structure optimization design method according to claim 6, characterized by, The box bottom plate (200) is made of aluminum alloy material, and the components other than the box bottom plate (200) and the beam structure (300) are made of carbon fiber material.

10. The finite element method-based battery case structure optimization design method according to any one of claims 1 to 9, characterized by, The step of modeling the battery box according to the design data of the battery box and performing finite element analysis includes the following steps: importing the three-dimensional data of the battery box into the finite element numerical simulation software, creating boundary conditions, and applying working condition load.

11. A battery box, characterized by The battery box structure optimization design method based on the finite element method according to any one of claims 1-10, wherein the battery box structure optimization design method comprises a box body and a battery module (100), the battery module (100) is contained in the box body, the box body comprises a box bottom plate (200) for bearing the battery module (100), and the box bottom plate (200) is provided with a beam structure (300).

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