A structural design optimization method for flexible lithium batteries of bionic vehicles based on co-simulation

Abstract

The present application discloses a method for optimizing the structure of a flexible lithium battery for a bionic vehicle based on joint simulation, specifically relating to the field of underwater energy systems. The method comprises: setting fixed structural parameters of the flexible lithium battery, and the optimization range and iteration interval of the structural parameters to be optimized; wherein, the shape of the flexible lithium battery is a waveform; establishing a multi-layer block mesh model of the flexible lithium battery, and projection auxiliary surfaces of components of each layer; projecting the meshes of the multi-layer block mesh model onto the projection auxiliary surfaces to obtain a flexible lithium battery; establishing a fin model and a skin model; setting fluid-solid coupling simulation parameters so that the flexible lithium battery is simulated under the fluid-solid coupling simulation parameters, and outputting the maximum equivalent stress of the flexible lithium battery; and taking the flexible lithium battery with the minimum maximum equivalent stress as the optimal flexible lithium battery structural component. Based on the above method, optimization time can be saved and manual intervention can be reduced.

Description

Technical Field

[0001] The present application relates to the field of underwater energy systems, and in particular to a method for optimizing the structure design of flexible lithium batteries for bionic vehicles based on joint simulation. Background Art

[0002] The new unmanned autonomous underwater bionic vehicle features strong maneuverability, high propulsion efficiency, and strong biocompatibility. It is widely applicable to marine environmental and biological testing and has become a key high-end underwater equipment subject to research and development. However, its complex internal structure presents problems such as low heterogeneous space utilization and low overall energy density. Compared to the technical difficulties of applying traditional batteries to bionic devices, such as large space occupation and limited energy gain, flexible energy storage technology provides a new approach to improving the heterogeneous space utilization and overall energy density of bionic vehicles. The application of flexible lithium batteries, under the premise that the bionic vehicle space allows and slightly affects the bionic motion posture of the vehicle, can effectively increase the overall energy carrying capacity, increase the overall energy density of the prototype, and extend the continuous operation time of the bionic vehicle.

[0003] Traditional submersibles have a relatively simple energy system, primarily based on conventional lithium-ion battery packs within the battery compartment. Due to significant space constraints, further increases in power are difficult. In addition to conventional lithium-ion battery packs located within the abdomen of the bionic submersible, flexible lithium-ion battery packs are added within the flapping wing compartment to improve the overall performance of the submersible. However, conventional flexible lithium-ion batteries are prone to structural deformation under repeated bending, resulting in performance defects and inability to operate normally. Furthermore, existing flexible lithium-ion battery simulation methods require modifying the three-dimensional model, importing the three-dimensional model to draw the mesh, then importing the mesh model for calculations, and then optimizing based on the calculation results. This process is repeated, requiring significant time and cumbersome operations to adjust the three-dimensional model and divide the mesh, leading to a long cycle of structural optimization. Summary of the Invention

[0004] The main purpose of this application is to provide a structural design optimization method for flexible lithium batteries of bionic vehicles based on joint simulation, aiming to solve the problem that conventional flexible lithium batteries are prone to structural deformation under repeated bending.

[0005] To achieve the above-mentioned purpose, the present application provides a method for designing and optimizing the structure of a flexible lithium battery for a bionic vehicle based on joint simulation, comprising: setting fixed structural parameters of the flexible lithium battery, and an optimization range and iteration interval of the structural parameters to be optimized; wherein, the shape of the flexible lithium battery is a waveform; according to the starting values ​​of the optimization range of the fixed structural parameters and the structural parameters to be optimized, a multi-layer block grid model of the flexible lithium battery and projection auxiliary surfaces of components of each layer are established; the grids in the length direction and the width direction of the multi-layer block grid model are projected onto the projection auxiliary surfaces respectively to obtain a flexible lithium battery; according to the flexible lithium battery, a corresponding fin model and a skin model are established, so that the flexible lithium battery is located on the surface of the fin model, and the flexible lithium battery and the fin model are located inside the skin model; setting fluid-solid coupling simulation parameters, wherein the fluid-solid coupling simulation parameters include fluid-solid coupling simulation Lagrangian structural parameters, applied loads and fluid parameters; the load is applied in a manner that a load is applied to the front section of the fin model so that the angular velocity of the fin model is ; Simulate the flexible lithium battery, fin model and skin model under the fluid-solid coupling simulation parameters, and output the maximum equivalent stress of the flexible lithium battery; sort the maximum equivalent stress values ​​of all flexible lithium batteries, and select the flexible lithium battery with the smallest maximum equivalent stress value as the optimal flexible lithium battery structural component.

[0006] Optionally, both the fixed structural parameters and the structural parameters to be optimized include a combination of one or more of waveform chord length, height, curvature radius, thickness of each battery layer, total battery length, battery width or position of the wavy section.

[0007] Optionally, after projecting the grids in the length and width directions of the multi-layer block grid model onto the projection auxiliary surface respectively, the method also includes assigning material numbers to the components of each layer of the flexible lithium battery, and dividing all components into sheet groups according to the motion state of the flexible lithium battery to obtain multiple sheet groups; setting the fluid-solid coupling simulation Lagrangian structure parameters, including setting material parameters for each material number; and setting the contact method between each sheet group and the fin model.

[0008] Optionally, the fluid parameters include density, viscosity coefficient and flow rate at standard temperature and standard atmospheric pressure.

[0009] Optionally, a fin ray model is established, including: setting the structural parameters of the fin ray, the structural parameters of the fin ray include the variable stiffness groove width, the variable stiffness starting position and the fin ray length; establishing a single-plane grid model of the fin ray, removing the notch according to the variable stiffness starting position and the variable stiffness groove width; setting material numbers for each component of the fin ray; dividing the node group according to the movement mode of the fin ray to obtain the fin ray model.

[0010] Optionally, setting the Lagrangian structure parameters for the fluid-solid coupling simulation further includes setting material parameters for the material number of each fin; and setting the motion mode of the node group.

[0011] Optionally, the flexible lithium battery assembly model is obtained through TrueGrid, and the input mode of TrueGrid is command stream.

[0012] Compared with the prior art, the present invention has the following advantages:

[0013] The present invention provides a method for optimizing the structure of a flexible lithium battery for a bionic vehicle based on joint simulation, which sets the structural parameters to be optimized and fixed parameters, and provides the optimization range and iteration interval of the parameters to be optimized. The structural parameters are automatically iteratively optimized and the model is automatically imported to automatically obtain the fluid-solid coupling simulation results of a waveform flexible lithium battery structure with different parameters, and the optimal structure is automatically compared, which can save optimization time and reduce manual intervention. The flexible lithium battery with a waveform structure can effectively disperse external stress and reduce material fatigue. The optimized flexible lithium battery can stably supply energy for a longer period of time under high-frequency bending conditions, providing more reliable protection for the maneuverability of the bionic submersible under long-term high-frequency bending conditions of flapping wings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a flow chart of a method for designing and optimizing a flexible lithium battery structure for a bionic vehicle based on joint simulation;

[0015] Figure 2 This is a flexible lithium battery structure diagram obtained by a flexible lithium battery structure design optimization method for a bionic vehicle based on joint simulation in this application;

[0016] Figure 3 This is a waveform structure diagram of a flexible lithium battery obtained by a method for designing and optimizing a flexible lithium battery for a bionic vehicle based on joint simulation in this application;

[0017] Figure 4 This is a structural diagram of the fin obtained by a method for designing and optimizing the structure of a flexible lithium battery for a bionic vehicle based on joint simulation;

[0018] Figure 5 This is a structural diagram of the skin obtained by a method for designing and optimizing the structure of a flexible lithium battery for a bionic vehicle based on joint simulation;

[0019] Figure 6 This is a schematic diagram of the contact between the components in a design optimization method for a flexible lithium battery structure of a bionic vehicle based on joint simulation;

[0020] Figure 7This is a load application diagram for a design optimization method of a flexible lithium battery structure for a bionic vehicle based on joint simulation in this application;

[0021] Figure 8 This is a fluid boundary setting diagram in a joint simulation-based design optimization method for a flexible lithium battery structure of a bionic vehicle;

[0022] Figure 9 This is a simulation process diagram of Example 1 of the present application;

[0023] Figure 10 The flexible lithium battery structure diagram and time course curve obtained in Example 1 of the present application;

[0024] Figure 11 This is a physical picture of the flexible lithium battery obtained in Example 1 of the present application;

[0025] Figure 12 The flexible lithium battery structure diagram and time course curve of Example 2 of the present application;

[0026] Figure 13 The flexible lithium battery structure diagram and time course curve of the comparative example of this application;

[0027] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0028] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0029] The first embodiment of the present invention provides a method for optimizing the structure of a flexible lithium battery for a bionic vehicle based on joint simulation. Figure 1 As shown, the specific steps include:

[0030] It is worth noting that in this embodiment, the flexible lithium battery models with different parameters are established using TrueGrid software. TrueGrid's input method is a command stream. That is, by inputting the command stream into TrueGrid, flexible lithium batteries with different parameters can be obtained. The specific command stream is shown in step S1-5.

[0031] Step S1, setting fixed structural parameters of the flexible lithium battery, and the optimization range and iteration interval of the structural parameters to be optimized; wherein the shape of the flexible lithium battery is a waveform, specifically as follows Figure 2As shown, the waveform is composed of two identical arcs, d is the chord length of the wave, h is the wave height, and r is the radius of the waveform.

[0032] It can be understood that fixed structural parameters are fixed structural parameters, and the structural parameters to be optimized are adjustable structural parameters. By changing the structural parameters to be optimized in sequence within the optimization range according to the iterative interval, flexible lithium battery models with different structural parameters can be obtained. Specifically, the fixed structural parameters and the structural parameters to be optimized include a combination of one or more of the following: waveform chord length, height, curvature radius, thickness of each battery layer, total battery length, battery width, or position of the wavy segment.

[0033] Step S2, establishing a multi-layer block mesh model of the flexible lithium battery and projection auxiliary surfaces of components of each layer according to the fixed structural parameters and the starting values ​​of the optimization range of the structural parameters to be optimized;

[0034] In this embodiment, the parametric modeling method can greatly improve the optimization efficiency, which is mainly reflected in the fact that the purpose of quickly adjusting the model can be achieved by simply changing individual parameters in the command stream. Compared with the cumbersome operation of adjusting the model using other modeling software, the use of parametric modeling plus automatic import to obtain a mesh model greatly reduces the time required to adjust the model during the structural optimization process. For example, if you need to adjust the battery length, you only need to change the value of l, the width to the value of a, and the thickness to the value of b. To adjust the waveform, you only need to modify any two of the wave height h, waveform radius r, and chord length h. In addition, by establishing an auxiliary line stretched as an auxiliary surface, the projection auxiliary surface of the surface can be quickly generated, and it can be directly and quickly adjusted by modifying the parameters in the command stream.

[0035] Step S3, project the grids in the length direction and width direction of the multi-layer block grid model onto the projection auxiliary surface respectively to obtain a flexible lithium battery, see Figure 2 , Figure 3 (a) is a parameterized model of a flexible lithium battery. Figure 3 Middle (b) is a schematic diagram of the battery layered structure. The flexible lithium battery includes from top to bottom an aluminum-plastic film, a negative electrode sheet (copper foil and graphite), a separator, a positive electrode sheet (ternary lithium), and an aluminum-plastic film.

[0036] In this embodiment, after projecting onto the projection auxiliary surface, the structure of the flexible lithium battery is obtained. Based on the structure, the material parameters of each component and the contact method between the flexible lithium battery and the fins need to be set during simulation. Therefore, material numbering and sheet group division are also required during modeling. Specifically, the following steps are performed: assigning material numbers to each layer of the flexible lithium battery components; dividing all components into sheet groups according to the motion state of the flexible lithium battery to obtain multiple sheet groups. The sheet groups are used to set the contact method between the flexible lithium battery and the fins. For example, the flat parts at both ends of the battery and the wavy section in the middle are defined as sheet group 1 and sheet group 2, respectively.

[0037] Step S4, establishing a fin model and a skin model;

[0038] The specific command flow is as follows: Step S41, setting the structural parameters of the fin ray; wherein the structural parameters of the fin ray include the variable stiffness slot width, the variable stiffness starting position and the fin ray length;

[0039] Step S42: Establish a single-plane mesh model of the fin, remove the notch according to the variable stiffness starting position and variable stiffness slot width, see Figure 4 , Figure 4 (a) is a three-dimensional image of a single-plane mesh model of a fin. Figure 4 (b) is a plan view of the single-plane mesh model of the fin.

[0040] Specifically, a single-plane mesh model of the fin is established by nesting a for loop within the block command to simplify the actual structure and improve simulation speed. A for loop is then used to remove the number of grooves u times, and the vd command is nested to set the notches to be removed as boxes. After the loop is completed, the de command is used to remove the notches to qualitatively achieve the change in stiffness of the fin from one side to the root, ensuring the bionic motion of the flapping wing from the fixed end to the tail. The specific code is as follows:

[0041] c fin plate fin ray

[0042] block 1 [nint(%zdz %k3)+1] [nint(%qbl %k3)+1]

[0043] for y 0 [%u-1] 1

[0044] [nint((%xst+%dn1 (1-%fac^(-%y)) / (1-%fac^(-1))+%j %y) %k3)+1]

[0045] [nint((%xst+%dn1 (1-%fac^(-%y)) / (1-%fac^(-1))+%j %y+%j) %k3)+1]

[0046] [nint((%xst+%dn1 (1-%fac^(-%y)) / (1-%fac^(-1))+%j %y+0.5 %dn1 / (%fac^%y)+0.5 %j) %k3)+1]

[0047] [nint((%xst+%dn1 (1-%fac^(-%y)) / (1-%fac^(-1))+%j %y+%j+0.5 %dn1 / (%fac^%y)+0.5 %j) %k3)+1]

[0048] endfor;

[0049] [nint(%ql %k3)+1];

[0050] 1 [nothing(40 %k3)+1];

[0051] -1;

[0052] 0 %zdz %qbl

[0053] for y 0 [%u−1] 1

[0054] [%xst+%dn1 (1-%fac^(-%y)) / (1-%fac^(-1))+%j %y]

[0055] [%xst+%dn1 (1-%fac^(-%y)) / (1-%fac^(-1))+%j %y+%j]

[0056] [%xst+%dn1 (1-%fac^(-%y)) / (1-%fac^(-1))+%j %y+0.5 %dn1 / (%fac^%y)+0.5 %j]

[0057] [%xst+%dn1 (1-%fac^(-%y)) / (1-%fac^(-1))+%j %y+%j+0.5 %dn1 / (%fac^%y)+0.5 %j]

[0058] endfor;

[0059] %ql; 10 50; 0;

[0062] nseti -2;;;or 1;

[0063] nseti 1 3;;;or 2;

[0064] mti 1 3;;;6;

[0065] mti 3 [4+4 %u];;;6;

[0066] for x 0 [%u-1] 1

[0067] vd [%x+1] box %x3 0 0 [%x3+%j][35+%x %dy] 0;

[0068] mtv 3 1 1 [4+4 %u] 2 1 [%x+1]2 99;

[0069] vd[%x+1+%u]box[%x3+0.5 %dn2+0.5 %j]50 0 [%x3+0.5 %dn2+1.5 %j] [25-%x %dy] 0;

[0070] mtv 3 1 1 [4+4 %u] 2 1 [%x+1+%u]2 99;

[0071] para x3 [%x3+%dn2+%j]

[0072] dn2 [%dn2 / %fac];

[0073] endfor;

[0074] de ;;;6;

[0075] endpart;

[0076] Step S43, setting material numbers for each component of the fin;

[0077] Step S44 : dividing the fin ray components into node groups according to the movement mode of the fin ray to obtain a fin ray model.

[0078] Exemplarily, each component of the fin is regarded as a node, the rotation axis node is regarded as node group 1, and the other nodes are regarded as node group 2.

[0079] Create a skin model according to the method of steps S41-44. Figure 5 .

[0080] Specifically, an auxiliary line in the shape of a runway is established. The auxiliary line is composed of two arcs with different radii and their common tangents, and the auxiliary line is stretched into an auxiliary surface. A single-face mesh model is established, projected onto the upper auxiliary surface, and material numbers are set for each component of the skin to obtain a skin model.

[0081] Step S5, setting fluid-solid coupling simulation parameters, wherein the fluid-solid coupling simulation parameters include structural parameters, applied loads, and fluid parameters;

[0082] Specifically, for flexible lithium batteries, the setting method of the Lagrangian structure parameters of the fluid-solid coupling simulation is to set the material parameters for each material number of the flexible lithium battery; set the contact mode of each plate group, specifically, plate group 1 is used to set the contact mode between the flexible lithium battery and the fin to fixed contact, and set plate group 2 is used to set the contact mode between the flexible lithium battery and the fin to free contact; the setting of plate group 1 and plate group 2 is essentially to simulate the interface behavior of the flexible lithium battery and the fin through the contact mechanics model. Fixed contact is used for rigid coupling scenarios, and free contact is used for flexible connections that allow relative motion.

[0083] For example, the contact between the fins and the skin and the flexible lithium battery is achieved as follows Figure 6 As shown, Figure 6 In (a), SPC boundaries are applied to all nodes of the fin and skin model to restrict their displacement and rotation in the width direction. The flexible lithium battery is fixed on the fin by Figure 6 In the implementation of the fixed contact shown in (b), all nodes on the lower surface of the flexible lithium battery electrode sheet end and tail end are selected and fixed to the fin surface; in order to simulate the active and passive deformation process of the battery as the fin moves, the wave segment cannot be fixed to the fin surface, and it is necessary to set Figure 6 Free contact shown in (c); set the fins and skin as Figure 6 The self-contact shown in (d) solves the mesh penetration problem caused by the deformation of the fins and skin during the simulation process; the fins move periodically, and the fins interact with the battery and skin structure to deform. This process requires the definition of Figure 6 The free contact between the several Lagrangian components shown in (e) above will not conform to the objective laws if this contact is not defined, and the fins will pass through the skin during movement.

[0084] For the fins, the Lagrangian structural parameters of the fluid-structure coupling simulation are set by setting the material parameters for each fin material number and setting the motion mode of the node group. Correspondingly, the load is applied to the front of the fin, so that the fin moves around the rotation axis with an angular velocity of , that is, node group 2 moves periodically around node group 1. The movement mode is shown in Figure 7 , specifically Figure 7 As shown in (a), the load is applied to the entire fin, that is, the node group 2 indicated by the blue triangle, and the fin performs periodic rotation around the node group 1 indicated by the red triangle, that is, the rotation axis. Figure 7 As shown in (b), the maximum phase angle of the periodic motion of the fin is 100°, and the motion period is 1s.

[0085] Furthermore, the fluid parameters include density, viscosity coefficient and flow rate at standard temperature and standard atmospheric pressure. For details, see Figure 8 The blue represents the skin, the green represents the inflow surface, and pressure boundary conditions are set on the remaining surfaces. Using incompressible fluids, the system automatically generates a volume mesh. Simply establish a fluid interface to automatically generate a fluid mesh within the area enclosed by the interface. Using implicit analysis combined with incompressible fluid simulation significantly reduces fluid mesh modeling time while improving simulation stability and computational efficiency.

[0086] Step S6, performing simulation operation on the flexible lithium battery model under fluid-structure coupling simulation parameters, and outputting the maximum equivalent stress value of the flexible lithium battery model;

[0087] It is worth noting that step S6 first performs a simulation trial run. If it works properly, proceed to step S6; if it does not work properly, return to step S5 to adjust the fluid-structure coupling simulation parameters until it works properly. In this embodiment, the maximum equivalent stress is calculated using an implicit method, employing implicit analysis + incompressible fluid simulation. The implicit method can perform iterative calculations throughout the entire time step, thus having high computational accuracy and stability, and can effectively handle nonlinear problems.

[0088] Step S7, re-establishing the multi-layer block mesh model of the flexible lithium battery in sequence according to the optimization range and iteration interval until the maximum equivalent stress of all flexible lithium battery models is output;

[0089] Specifically, taking the starting value of the optimization range as the structural parameter to be optimized of the initial model, the first flexible lithium battery can be obtained according to step S2-3, and then the first flexible lithium battery assembly model can be obtained according to step S4, and each flexible lithium battery assembly model is simulated according to step S5-6; after each simulation of a structure is run and the result is automatically output, the structural parameter to be optimized automatically increases by one iteration interval, and then the next structural simulation is run, that is, each time step S2 is returned, the structural parameter to be optimized automatically increases by one iteration interval. Although the structural parameters of the fins and skins are unchanged, they need to be combined with flexible lithium batteries of each parameter. Therefore, the number of fin and skin models required is corresponding to the number of flexible lithium batteries. For each flexible lithium battery established, a fin and skin model needs to be established.

[0090] Step S8, sorting the maximum equivalent stress values ​​of all flexible lithium battery models, and taking the flexible lithium battery model with the minimum maximum equivalent stress value as the optimal flexible lithium battery structure.

[0091] Specifically, the simulations of all flexible lithium battery models are compared, and the optimal parameters are output, i.e., the parameters of the flexible lithium battery model with the smallest maximum equivalent stress. In this embodiment, the grid model is adjusted directly through the command stream, the structural parameters are automatically iteratively optimized, the parameters are automatically modified using a script, and the model is automatically imported. After the simulation is adjusted, the fluid-structure coupling simulation results of the wavy flexible lithium battery structure with different parameters can be automatically obtained, and the optimal structure can be automatically compared. Compared with other methods that require complex model adjustment steps, long costs, and time-consuming and labor-intensive manual comparison, this method saves a lot of optimization time and reduces manual intervention.

[0092] As you can understand, the maximum stress value is at the weakest point in the structure, where the battery is most likely to fail due to excessive stress. Minimizing the stress at this point maximizes the safety margin, preventing yielding, fracture, and local damage to key components (diaphragms, active materials), thereby improving the battery's durability while meeting other necessary constraints (such as space, weight, cost, heat dissipation, and electrical performance). Therefore, this example uses the flexible lithium battery model with the lowest maximum equivalent stress value as the optimal flexible lithium battery structure.

[0093] Example 1

[0094] S1. Set the wave height of the flexible lithium battery to 0.66 mm, the waveform radius to 1.3 mm–3 mm, and the iteration interval to 0.2 or 0.3 mm. The wave starting position wst is 10 mm, and the battery length l, thickness b, and width a are 80 mm, 2 mm, and 16 mm, respectively.

[0095] Fin ray parameters: m is the fin ray stiffness interval progressive coefficient 0.1, j is the fin ray stiffness groove width 2, dy is the stiffness depth progressive amount 1 (i.e., the previous groove is 1mm deeper than the next groove), the number of stiffness grooves on one side of u is 10, xst is the starting position of stiffness change 55mm, len is the total length of the stiffness change section 210mm, ql is the total length of the fin ray 280mm, and qbl is the fin ray length 30mm.

[0096] Skin parameters: large circle inner radius r_max_in 4.5mm, large circle outer radius r_max_out 6.5mm, small circle inner radius r_min_in 3mm, small circle outer radius r_min_out 5mm, maximum distance between the two inner circles d_rr_in 284mm, skin width d_w 60mm;

[0097] S2. Automatically import TrueGrid to obtain the models of the flexible lithium battery, fins, and skin;

[0098] S3. Simulation parameter settings:

[0099] Load related: x0 axis initial x coordinate 0.0115, rx0 maximum phase angle 50°, Tr0 rotation period 1s,

[0100] Time step: NT calculation termination cycle number 2s, dt0 implicit calculation initial time step 0.01s, minimum time step 1e-4s, maximum time step 0.01s,

[0101] Shell element thickness and contact: fin thickness 0.002m, skin thickness 0.002m, contact stiffness 0.3,

[0102] ICFD: mgsf grid generation ratio 1.2, nelth boundary grid layer number 4, blth boundary layer thickness 0.01m, blfe boundary layer grid asymptotic ratio 0.8, minh adaptive grid minimum size 0.030m, maxh adaptive grid maximum size 0.032m, nit grid division iteration interval 15, v water velocity 1.0m / s, h water depth 1m, tp0 boundary initialization time 0.1s;

[0103] S4. Simulate the flexible lithium battery model under the fluid-structure coupling simulation parameters of S3. The simulation of a single structure takes about 36 minutes. See the process for details. Figure 9 ,The fins drive the flexible lithium battery fixed on them to swing and interact with the skin;

[0104] S5. After each structure simulation is run and the results are automatically output, the radius automatically increases, and then the next structure simulation is run;

[0105] S6. Compare the maximum equivalent stress of the flexible lithium battery under different parameters in the results, and compare the improvement in stress resistance of the non-optimized battery, see Table 1;

[0106] Table 1 Simulation operation data

[0107]

[0108] S7. Output the structural stress distribution with the minimum and maximum equivalent stress values ​​and the maximum unit time history curve, such as Figure 10 As shown; the flexible lithium battery with the smallest maximum equivalent stress is regarded as the optimal flexible lithium battery, the actual object is shown Figure 11 .

[0109] Example 2

[0110] S1. Set the waveform radius to a fixed value of 1.5 mm, the wave height range to 0.22 mm to 1.10 mm, and increase the wave height by 0.22 mm for each simulation (ie, the iteration interval is 0.22 mm); the remaining parameters are the same as in Example 1;

[0111] S2. Automatically import TrueGrid to obtain the models of the flexible lithium battery, fins, and skin;

[0112] S3. The specific simulation parameters are the same as those in Example 1;

[0113] S4. Simulate the flexible lithium battery model under the fluid-solid coupling simulation parameters of S3;

[0114] S5. After each structural simulation is run and the results are automatically output, the radius automatically increases and the process returns to S2 to run the next structural simulation.

[0115] S6. Compare the maximum equivalent stress of the flexible lithium battery under different parameters in the results, and compare the improvement in stress resistance of the non-optimized battery, see Table 2;

[0116] Table 2 Simulation operation data

[0117]

[0118] S7. Output the structural stress distribution with the minimum and maximum equivalent stress values ​​and the maximum unit time history curve, such as Figure 12 shown.

[0119] By comparing the results of Examples 1-2, it was found that the maximum equivalent stress of the flexible lithium battery wavy structure with a wave height of 1.1 mm and a wave radius of 1.5 mm was the smallest.

[0120] Comparative example (without wave-shaped structure design optimization)

[0121] S1. Set the wave height and wave radius to 0.

[0122] S2. According to the above simulation process, the maximum value of equivalent stress, stress distribution at the time of occurrence and the equivalent stress time history curve of the unit with the maximum value of equivalent stress are output. Figure 13 ;

[0123] from Figure 10 and 13 It can be concluded that the maximum equivalent stress of the flexible lithium batteries of Examples 1 and 2 is reduced by at least 20% compared with the unoptimized flexible lithium battery in the control example. This shows that the wavy structure enables the flexible lithium battery to exhibit better anti-bending performance.

[0124] The above are only preferred embodiments of the present application and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for designing and optimizing the structure of flexible lithium batteries for bionic vehicles based on joint simulation, characterized in that: include: Setting fixed structural parameters of a flexible lithium battery, and an optimization range and iteration interval of the structural parameters to be optimized; wherein the shape of the flexible lithium battery is a waveform; Establishing a multi-layer block mesh model of the flexible lithium battery and projection auxiliary surfaces of components of each layer according to the fixed structural parameters and the starting values ​​of the optimization range of the structural parameters to be optimized; Projecting the grids in the length direction and the width direction of the multi-layer block grid model onto the projection auxiliary surface respectively to obtain a flexible lithium battery; According to the flexible lithium battery, a corresponding fin model and a skin model are established, so that the flexible lithium battery is located on the surface of the fin model, and the flexible lithium battery and the fin model are located inside the skin model; Set the fluid-solid coupling simulation parameters, wherein the fluid-solid coupling simulation parameters include the fluid-solid coupling simulation Lagrangian structure parameters, applied load and fluid parameters; the load is applied in the way that the load is applied to the front section of the fin model so that the angular velocity of the fin model is ; The flexible lithium battery, fin model, and skin model are simulated and run under fluid-solid coupling simulation parameters to output the maximum equivalent stress of the flexible lithium battery; The maximum equivalent stress values ​​of all the flexible lithium batteries are sorted, and the flexible lithium battery with the smallest maximum equivalent stress value is selected as the optimal flexible lithium battery structural component.

2. The method for designing and optimizing the structure of a flexible lithium battery for a bionic vehicle based on joint simulation according to claim 1, characterized in that: The fixed structural parameters and the structural parameters to be optimized both include a combination of one or more of waveform chord length, height, curvature radius, thickness of each battery layer, total battery length, battery width or wave section position.

3. The method for designing and optimizing the structure of a flexible lithium battery for a bionic vehicle based on joint simulation according to claim 1, characterized in that: After projecting the grids in the length direction and the width direction of the multi-layer block grid model onto the projection auxiliary surface respectively, the method further includes: Assigning material numbers to components of each layer of the flexible lithium battery, and dividing all components into sheet groups according to the motion state of the flexible lithium battery to obtain multiple sheet groups; The Lagrangian structural parameters for fluid-solid coupling simulation are set as follows: Set material parameters for each material number; Set the contact method between each sheet group and the fin model.

4. The method for designing and optimizing the structure of a flexible lithium battery for a bionic vehicle based on joint simulation according to claim 1, characterized in that: The fluid parameters include density, viscosity coefficient and flow rate at standard temperature and standard atmospheric pressure.

5. The method for designing and optimizing the structure of a flexible lithium battery for a bionic vehicle based on joint simulation according to claim 1, characterized in that: Build a fin ray model, including: Setting the structural parameters of the fin ray, wherein the structural parameters of the fin ray include variable stiffness slot width, variable stiffness starting position and fin ray length; Establishing a single-plane mesh model of the fin, and removing the notch according to the variable stiffness starting position and the variable stiffness slot width; Set material numbers for each component of the fin; The node groups are divided according to the movement mode of the fin ray to obtain the fin ray model.

6. The method for designing and optimizing the structure of a flexible lithium battery for a bionic vehicle based on joint simulation according to claim 5, wherein the setting of the Lagrangian structural parameters for fluid-structure coupling simulation further comprises: Set material parameters for each fin material number; Set the movement mode of the node group.

7. According to the joint simulation-based flexible lithium battery structure design optimization method for bionic aircraft in claim 1, the flexible lithium battery component model is obtained through TrueGrid, and the input mode of TrueGrid is command stream.

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