Rapid convergence power battery bottom ball hit simulation modeling method

Abstract

The invention belongs to the technical field of new energy automobiles, and relates to a fast convergence power battery bottom ball hit simulation modeling method, which comprises the following steps: bottom ball hit position selection: selecting the center position of the lower surface of a single cell; the transverse longitudinal beam and the frame are far away as far as possible; the bottom guard plate plane position is selected as far as possible; the water-cooling plate plane position is selected as far as possible; establishing a grid model at the ball hit part of the bottom guard plate; the impact ball is in contact with the bottom protection plate; refining a part grid model on a ball hit path; establishing a filler grid and contact; boundary and load definition; and defining load step and convergence control. According to the power battery bottom ball strike simulation modeling method with rapid convergence, the power battery bottom ball strike simulation convergence can be effectively improved, the model debugging time of a simulation engineer is saved, the calculation and solving time of a simulation model is shortened, the simulation efficiency is improved, and the research and development cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of new energy vehicles, and in particular relates to a fast-converging power battery bottom ball hitting simulation modeling method. Background Art

[0002] Power batteries are an important component of new energy vehicles and are used to power the entire vehicle. Once a power battery is damaged by external impact, not only will the entire vehicle's power system be paralyzed, but there is also a high probability that fires, explosions, and other accidents will occur, seriously threatening the safety of life and property.

[0003] The bottom ball impact test of power batteries is an effective method to verify the impact resistance of batteries. However, its test risks and costs are very high. Therefore, in the early stage of battery development, finite element simulation is often used to replace part of the bottom ball impact test, so as to improve R&D efficiency and reduce test costs. However, when simulating the bottom ball impact condition, the simulation model involves a large number of nonlinear factors such as material nonlinearity, geometric nonlinearity, and contact nonlinearity. These nonlinear factors will cause the convergence of the model to become very poor, and often require simulation engineers to invest a lot of time in model convergence debugging. Moreover, the calculation and solution speed of the debugged model is also very slow, which also seriously affects the R&D efficiency.

[0004] Therefore, it is urgent to develop an effective and fast-converging power battery bottom ball impact simulation modeling method to effectively solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to provide a fast-converging power battery bottom ball impact simulation modeling method to solve the problem of effectively improving the convergence of the power battery bottom ball impact simulation.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] A fast-converging power battery bottom ball impact simulation modeling method comprises the following steps.

[0008] S1, bottom ball hitting position selection;

[0009] S2, establishment of mesh model of the ball hitting position of the bottom guard plate;

[0010] S3, the impact ball is in contact with the bottom guard plate;

[0011] S4, refinement of mesh model of components on the ball hitting path;

[0012] S5, filler mesh and contact establishment;

[0013] S6, boundary and load definition;

[0014] S7. Load step and convergence control definition.

[0015] Furthermore, in step S1, the bottom ball hitting position is selected in accordance with the following principles: the center of the lower surface of the single cell is preferentially selected and is away from the horizontal and vertical beams and the frame; the bottom guard plate plane position is selected as much as possible; and the water cooling plate plane position is selected as much as possible.

[0016] Furthermore, step S2 specifically includes the following steps:

[0017] S21, mapping the impact ball grid to the bottom guard plate plane to replace the original regional grid, forming a circular radial shell unit grid;

[0018] S22, re-dividing at least two layers of meshes on the periphery of the circular area so that their common nodes connect the original shell unit mesh of the bottom guard plate and the circular radial shell unit mesh;

[0019] S23. Use the circular area and at least two layers of mesh on the periphery as a boundary frame to select a square shell unit mesh area, and stretch the shell unit mesh of the square area up and down to form two layers of solid unit mesh. The thickness of the two layers of mesh is consistent with the actual thickness of the bottom guard plate. The solid mesh is the mesh of the bottom guard plate where the ball hits.

[0020] Furthermore, in step S3, the circular radial mesh and the spherical mesh in S2 are selected as master and slave surfaces to establish contact, using surface-to-surface contact.

[0021] Furthermore, in step S4, the water cooling plate mesh refinement area is a square area with the same center as the circular area in S2, the square area is greater than or equal to the square area in S2, and the maximum size of the refined mesh is less than 2 mm; for monomer components, only monomers are refined, and the maximum mesh size of the refined area is less than 2 mm.

[0022] Furthermore, in step S5, a filler is established between the bottom guard plate and the lower plate of the liquid cooling plate and between the upper and lower plates of the water cooling plate, and the shape is consistent with the shape of the cavity between the bottom guard plate and the water cooling plate and between the upper and lower plates of the water cooling plate; the elastic modulus of the filler can be changed, and the change criterion is: the deformation effect on the bottom guard plate and the liquid cooling plate is as small as possible; the thickness of the filler after being compressed should not be zero or negative; the filler is divided into a solid grid, and the grid in the thickness direction is at least 3 layers, except that the maximum grid size in the thickness direction is less than 2mm; the contact between the filler and the bottom guard plate and the water cooling plate is Tie connection.

[0023] Furthermore, in step S6, the loading form adopted is a mixed loading method of first using forced displacement loading and then using force loading.

[0024] Furthermore, the displacement size is 0.1 mm and the loaded force is 20 or 25 kN.

[0025] Furthermore, in step S7, the initial increment of the forced displacement load step is set to 0.01, the total step size is 0.2, and the incremental step size is 0.01.

[0026] Furthermore, the force load step is set with an initial increment of 1e-3, a total step of 1, an increment of 1e-5, and contact stability control with a coefficient of 0.01.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The fast-converging power battery bottom ball impact simulation modeling method of the present invention can effectively improve the convergence of the power battery bottom ball impact simulation, save simulation engineers' model debugging time, reduce simulation model calculation and solution time, improve simulation efficiency, and reduce research and development costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 Flowchart of the fast-converging power battery bottom ball impact simulation modeling method;

[0031] Figure 2 Bottom ball hitting position diagram;

[0032] Figure 3 Impact ball grid model diagram;

[0033] Figure 4 Schematic diagram of the grid mapping of the ball impact point on the bottom guard plate;

[0034] Figure 5 Schematic diagram of the solid mesh of the bottom guard plate;

[0035] Figure 6 Refinement of mesh model of water-cooled cricket batting position;

[0036] Figure 7 Battery pad mesh model refinement;

[0037] Figure 8 Refinement of the single cell grid model;

[0038] Fig. 9 Schematic diagram of the filling shape and grid; Fig.10 Bottom ball hit simulation model. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with embodiments:

[0040] like Figure 1 As shown, the fast-converging power battery bottom ball hitting simulation modeling method of the present invention comprises the following steps:

[0041] S1. Selection of bottom ball hitting position

[0042] The bottom ball hitting position should follow the following principles in order of priority:

[0043] 1. Select the center position of the lower surface of the single cell; 2. Keep away from the horizontal and vertical beams and frames as much as possible; 3. Select the flat position of the bottom guard plate as much as possible; 4. Select the flat position of the water cooling plate as much as possible.

[0044] S2. Establishment of mesh model of ball impact point on bottom guard plate

[0045] The impact ball mesh is mapped to the bottom guard plate plane to replace the original area mesh, forming a circular radial shell unit mesh. Then, the at least two layers of mesh outside the circular area are re-divided so that their common nodes connect the original shell unit mesh of the bottom guard plate and the circular radial shell unit mesh. Then, the circular area and at least two layers of mesh outside are used as the boundary box to select a square shell unit mesh area, and the shell unit mesh of the square area is stretched up and down to form two layers of solid unit mesh. The thickness of the two layers of mesh is consistent with the actual thickness of the bottom guard plate. This solid mesh is the mesh of the bottom guard plate where the ball hits. S3. Contact between the impact ball and the bottom guard plate is established

[0046] Select the circular radial mesh and the spherical mesh in step S2 as master and slave surfaces to establish contact, using surface-to-surface contact.

[0047] S4. Refinement of mesh model of components on the ball hitting path

[0048] The water cooling plate, rubber pad, and battery cell on the ball hitting path are meshed. The meshing area of ​​the water cooling plate is a square area with the same center as the circular area in step S2, and the square area is greater than or equal to the square area in step S2. For single-body components, only single-body components need to be meshed, and the maximum size of all meshes is less than 2mm.

[0049] S5. Filler mesh and contact establishment

[0050] Fill the bottom guard plate, the water-cooling plate, and the water channel of the water-cooling plate with a filler having an upper elastic modulus of 1, whose shape is consistent with the shape of the cavity between the bottom guard plate and the water-cooling plate and between the upper and lower plates of the water-cooling plate, and whose filling range is greater than or equal to the square area in step S2. The filler is a solid grid, which is divided into at least 3 layers in the thickness direction, and the maximum size of the grid except the thickness direction is less than 2 mm.

[0051] The contact between the filler and the bottom guard plate and the water-cooled plate is iron.

[0052] S6. Boundary and load definitions

[0053] Fully constrained fixture degrees of freedom. Constrain the impact ball except for the degrees of freedom in the impact direction, and load the degrees of freedom in the impact direction. The loading form is to first use forced displacement loading to establish stable contact, with a displacement size of 0.1mm. Then force loading is applied, the size is consistent with the test standard, generally 20 or 25kN.

[0054] S7, Load Step and Convergence Control Definition

[0055] The initial increment of the forced displacement load step is set to 0.01, the total step size is 0.2, and the minimum increment size is 0.01. The initial increment of the force load step is set to 1e-3, which can be adjusted according to the model, generally 1e-3 to 1e-5, and the increment is 1e-5, which can be adjusted according to the model, generally 1e-3 to 1e-9. Turn on contact stability control, the coefficient is 0.01, which can be adjusted according to the model, generally 0.01 to 0.05.

[0056] Example 1

[0057] S1. Selection of bottom ball hitting position

[0058] like Figure 2 As shown, the bottom ball hitting position is selected according to the following principles:

[0059] 1. Select the geometric center position of the single cell; 2. Keep it as far away from the horizontal and vertical beams and frames as possible; 3. Select the flat position of the bottom guard plate as much as possible; 4. Select the flat position of the water cooling plate as much as possible.

[0060] S2. Establishment of mesh model of ball hitting position on bottom guard plate

[0061] like Figure 3 The figure shows the mesh model of the impact ball. The mesh is mapped on the bottom guard plate to form Figure 4 The circular radial grid is shown. Delete the original grid of the bottom guard plate in the circular area, and re-divide the outer periphery of the circular area by at least 2 layers of grids, so that the original grid of the bottom guard plate and the circular mapping grid share nodes. Figure 5 As shown, Figure 4 The grid of the square area shown is stretched up and down to form a solid grid with the same thickness as the bottom guard plate.

[0062] Specifically, the mesh at the impact point of the bottom guard plate is a solid mesh, and the solid mesh shares nodes with the peripheral shell unit mesh. The solid mesh is formed by stretching the square area shell unit mesh up and down into two layers, and the thickness of the solid mesh is equal to the thickness of the bottom guard plate. The square area shell unit mesh is based on the circular radial shell unit mesh, and at least 2 layers of mesh are extended outward as the boundary box. The circular radial shell unit mesh is formed by mapping the impact ball mesh on the bottom guard plate plane, and its purpose is to make the master and slave mesh sizes of the impact ball and the bottom guard plate contact pair similar to improve the contact quality. The mapped mesh shape is a radial circle, not other shapes. During impact, the radial circular mesh has a smoother deformation trend.

[0063] S3, the contact surface between the impact ball and the bottom guard plate is established

[0064] choose Figure 3 The spherical mesh is used as the contact slave surface, and the Figure 4 The mesh of the circular area is used as the main contact surface, and contact is established. The contact type is selected as surface-to-surface contact.

[0065] S4. Refinement of mesh model of components on the ball hitting path

[0066] like Figure 6 As shown, the water cooling plate mesh is refined, and the water cooling plate mesh refinement area is a square area with the same center as the circular area in S2, the square area is greater than or equal to the square area in step S2, and the maximum size of the refined mesh is less than 2mm. Figure 7 , 8 As shown, the battery pad and single cell grids are refined, and the maximum size of the refined grid is less than 2 mm.

[0067] S5. Filler mesh and contact establishment

[0068] like Fig. 9 As shown in the figure, a filler with an elastic modulus of 1 is established between the lower plate of the water-cooled plate and the bottom guard plate, and between the upper and lower plates of the water-cooled plate. The shape is consistent with the shape of the cavity between the bottom guard plate and the water-cooled plate, and between the upper and lower plates of the water-cooled plate. The filler is divided into at least 3 layers of solid meshes, and the maximum mesh size is less than 2mm except in the thickness direction. The contact established between the filler and the water-cooled plate and the bottom guard plate is Tie contact, and the type is selected as surface-to-surface contact.

[0069] S6. Definition of ball impact boundary and load

[0070] like Fig.10 As shown, the two side fixtures (4 on each side, 4 pairs in total) are constrained to have 1 to 6 degrees of freedom, and the impact ball is constrained to have all degrees of freedom except the impact direction, and loaded in the impact direction. The loading form is to first establish stable contact with forced displacement loading, with a displacement size of 0.1mm. Then force loading is applied, with a size of 20kN.

[0071] S7, Load Step and Convergence Control Definition

[0072] The initial increment of the forced displacement load step is set to 0.01, the total step size is 0.2, and the minimum increment step is 0.01. The initial increment of the force load step is set to 1e-3, the total step size is 1, the minimum increment step is 1e-5, and the contact stability control is set with a coefficient of 0.01.

[0073] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A fast-converging power battery bottom ball impact simulation modeling method, characterized in that: The following steps are included. S1, bottom ball hitting position selection; S2, establishment of mesh model of the ball hitting position on the bottom guard plate; S3, the impact ball is in contact with the bottom guard plate; S4, refinement of mesh model of components on the ball hitting path; S5, filler mesh and contact establishment; S6, boundary and load definition; S7. Load step and convergence control definition.

2. A fast-converging power battery bottom ball hitting simulation modeling method according to claim 1, characterized in that: In step S1, the bottom ball hitting position is selected according to the following principles: the center of the lower surface of the single cell is selected first and is away from the horizontal and vertical beams and the frame; the bottom guard plate plane position is selected as much as possible; and the water cooling plate plane position is selected as much as possible.

3. A fast-converging power battery bottom ball hitting simulation modeling method according to claim 1, characterized in that: Step S2 specifically includes the following steps: S21, mapping the impact ball grid to the bottom guard plate plane to replace the original regional grid, forming a circular radial shell unit grid; S22, re-dividing at least two layers of meshes on the periphery of the circular area so that their common nodes connect the original shell unit mesh of the bottom guard plate and the circular radial shell unit mesh; S23. Use the circular area and at least two layers of mesh on the periphery as a boundary frame to select a square shell unit mesh area, and stretch the shell unit mesh of the square area up and down to form two layers of solid unit mesh. The thickness of the two layers of mesh is consistent with the actual thickness of the bottom guard plate. The solid mesh is the mesh of the bottom guard plate where the ball hits.

4. A fast-converging power battery bottom ball hitting simulation modeling method according to claim 1, characterized in that: In step S3, the circular radial mesh and the spherical mesh in S2 are selected as the master and slave surfaces to establish contact, using surface-to-surface contact.

5. A fast-converging power battery bottom ball hitting simulation modeling method according to claim 1, characterized in that: In step S4, the water cooling plate mesh refinement area is a square area with the same center as the circular area in S2, the square area is greater than or equal to the square area in S2, and the maximum size of the refined mesh is less than 2 mm; For monomer parts, only the monomer is refined, and the maximum grid size of the refined area is less than 2mm.

6. A fast-converging power battery bottom ball hitting simulation modeling method according to claim 1, characterized in that: In step S5, a filler is established between the bottom guard plate and the lower plate of the liquid cooling plate and between the upper and lower plates of the water cooling plate, and the shape is consistent with the shape of the cavity between the bottom guard plate and the water cooling plate and between the upper and lower plates of the water cooling plate; the elastic modulus of the filler can be changed, and the change criterion is: the deformation effect on the bottom guard plate and the liquid cooling plate is as small as possible; the thickness of the filler after being compressed should not be zero or negative; the filler is divided into a solid grid, and the grid in the thickness direction is at least 3 layers, except that the maximum grid size in the thickness direction is less than 2mm; the contact between the filler and the bottom guard plate and the water cooling plate is Tie connection.

7. A fast-converging power battery bottom ball hitting simulation modeling method according to claim 1, characterized in that: In step S6, the loading method adopted is a mixed loading method of first using forced displacement loading and then using force loading.

8. A fast-converging power battery bottom ball hitting simulation modeling method according to claim 7, characterized in that: The displacement size is 0.1 mm and the loaded force is 20 or 25 kN.

9. A fast-converging power battery bottom ball hitting simulation modeling method according to claim 1, characterized in that: In step S7, the initial increment of the forced displacement load step is set to 0.01, the total step size is 0.2, and the incremental step size is 0.

01.

10. A fast-converging power battery bottom ball hitting simulation modeling method according to claim 9, characterized in that: The force load step sets the initial increment to 1e-3, the total step size to 1, the increment to 1e-5, and the contact stability control with a coefficient of 0.01.

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