Simulation analysis method for vibration impact of fuel cell stack

Abstract

The invention discloses a fuel cell stack vibration impact simulation analysis method. The method comprises the following steps: S1, determining a vibration working condition and an impact working condition; s2, calculating the mass of an electric pile core, the mass of system accessories and the three-axis rotational inertia; s3, simplifying the three-dimensional numerical model; s4, carrying out pre-processing grid division; s5, solving setting is carried out; and S6, performing post-processing on a result. According to the fuel cell stack vibration impact simulation analysis method, through model simplification of a fuel cell stack packaging assembly and a shell and equivalence of mass point effects of a reactor core and system accessories, the calculation amount during fuel cell stack vibration impact simulation analysis can be reduced, and meanwhile, a relatively accurate numerical simulation result is obtained; and a theoretical basis and a data support are provided for structural optimization and material selection of the fuel cell stack packaging assembly. Therefore, the adverse effect of the vibration impact stack fuel cell stack is weakened, and the reliability and durability of the fuel cell stack are improved. Meanwhile, the proofing test of the numerical simulation analysis sample checking machine can be carried out at the initial stage of design, so that the research and development period is greatly shortened, and the rapid iteration of the fuel cell stack is facilitated.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cell electrical simulation analysis, and in particular, relates to a fuel cell stack vibration impact simulation analysis method. Background Art

[0002] Proton exchange membrane fuel cells convert chemical energy generated by fuel and oxidant into electrical energy through direct electrochemical reaction. It is a perfect solution to resolve energy conflicts. Hydrogen fuel cell technology uses hydrogen as fuel and oxygen in the air as oxidant. Through two and a half chemical reactions, the anode is: 2H2→4H + +4e - ; cathode: O2+4H + +4e - →2H20 converts chemical energy into electrical energy, and its overall reaction is 2H2+O2=2H20. Its only emission product is water, which has the advantages of environmental protection, high power density, low operating temperature, and fast startup. The proton exchange membrane fuel cell stack is mainly composed of a core and a packaging assembly, in which the core is stacked by hundreds of membrane electrodes and bipolar plates, and its mass accounts for 60% to 80% of the entire stack module. The packaging assembly is located outside the membrane electrode and bipolar plate, and plays the role of mechanical support, heat insulation and sealing. It is mainly composed of a packaging end plate and a shell. When the stack module and system accessories are assembled to form a hydrogen fuel cell system, connection points are set on the end plate and the shell to fix the system accessories, and the hydrogen fuel cell system is installed on the frame through the installation points on the packaging end plate and the shell to complete the assembly of the hydrogen fuel cell vehicle system power system.

[0003] The proton exchange membrane fuel cell stack is subjected to continuous vibration and impact loads during the driving of hydrogen fuel cell vehicles. Vibration and impact verification plays an important role in product development and quality control. Considering the cost of the proton exchange membrane fuel cell stack prototype, structural risks are identified in the early stage of structural design. Vibration and impact simulation analysis can be used to evaluate the vibration resistance, structural rationality and design rationality of the product, thereby improving the reliability and safety of the product. This simulation and analysis method based on computer technology obtains corresponding results and data by mathematically modeling and calculating the data model in the early stage of product design. It can optimize the design scheme, improve product quality and reduce development costs.

[0004] In the prior art, the vibration characteristics analysis of fuel cell stacks is often carried out by establishing a mechanical finite element model based on traditional calculation methods. Some of these methods only simulate the core of the fuel cell stack, without considering the coupling effect at the system level, and their simulation results cannot provide a basis for judging the structural strength from top to bottom; some consider the influence of packaging components and system accessories, but because the core is a cross-scale structure, the number of grids is huge during calculation, which requires high computing power and a long calculation cycle, which has a great impact on the product development cycle, and there are also problems with its calculation convergence and calculation accuracy.

[0005] The Chinese patent application number 201711004798.7 discloses a structural design method for improving the pressure distribution in a fuel cell stack. An equivalent stiffness-mass model is proposed, which can efficiently analyze the structural stress of the PEMFC, so that the design of structures such as bosses can be efficiently completed. The boss structure is processed on the bipolar plate to allow it to bear part of the packaging force and external dynamic load. More battery inertia forces are borne by the bipolar plate with higher strength, thereby reducing the amplitude of the cyclic stress on the components in the battery and extending its service life. Through such a bipolar plate boss structure force design, the role of protecting the membrane electrode and the seal can be well played. However, the invention only simulates the core composed of the membrane electrode and the bipolar plate, and the fuel cell stack usually needs to be integrated with the shell when it is actually installed on the vehicle, on the one hand to protect the core, and on the other hand to install system accessories on the shell. Therefore, under actual working conditions, the influence of the shell on the core is ignored, and the influence on the core under vibration conditions is only analyzed independently, and the impression of decoupling the shell and system accessories cannot fully evaluate the reliability of the stack structure.

[0006] The Chinese patent with application number 202122797768.4 discloses a method for improving the vibration and impact resistance of a fuel cell engine casing, including: establishing a finite element mechanical performance simulation model; defining the relative constraint position design parameters of the fuel cell engine casing; analyzing the response of the casing and the fuel cell stack finite element model under different test conditions; modifying the defined design parameters, and simulating until a set of model response results is obtained; combining the structure and working characteristics of the fuel cell engine casing and the fuel cell stack, determining the vibration and impact resistance performance evaluation index, and establishing the relationship between the response results and the performance; screening the design parameter range that meets the requirements, and determining the optimal design parameter combination according to the response results of the fuel cell stack. However, the invention has no special treatment for the core. The fuel cell stack is composed of hundreds of membrane electrodes, and its scale includes decimeter, millimeter and even micrometer levels. The direct modeling analysis method is used to calculate the poor quality of the grid. On the one hand, this setting requires a lot of computing power, and on the other hand, the calculation convergence takes a long time, which is not conducive to the rapid optimization design of the product, and the accuracy of the simulation results cannot be guaranteed.

[0007] It is hoped to provide an improved fuel cell stack vibration and shock simulation analysis method, particularly with respect to improving the accuracy of fuel cell stack vibration and shock simulation results and reducing the amount of calculation during fuel cell stack vibration and shock simulation analysis. Summary of the invention

[0008] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a fuel cell stack vibration impact simulation analysis method, the purpose of which is to reduce the amount of calculation in the fuel cell stack vibration impact simulation analysis and improve work efficiency.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is: a fuel cell stack vibration impact simulation analysis method, comprising the steps of:

[0010] S1. Determine vibration and impact conditions;

[0011] S2. Calculation of the fuel cell stack core mass, system auxiliary parts mass and three-axis rotational inertia;

[0012] S3, simplified processing of three-dimensional numerical model;

[0013] S4, pre-processing grid division;

[0014] S5, solution setting;

[0015] S6. Post-processing of results.

[0016] In step S1, the impact test method used is: applying a half-sine shock wave with an acceleration value of 25-30g and a pulse time of Nms to the fuel cell module. The test will be carried out in five directions of ±x, ±y and +z, and the number of impacts in each direction is M times.

[0017] In the step S1, N is 5-7, and M is 5-7.

[0018] In step S2, when the core and system auxiliary parts have regular shapes, the masses of the core and system auxiliary parts are calculated according to the formula m=ρV, where m is the mass, ρ is the material density, and V is the volume of the parts;

[0019] According to the formula I = mr 2 Calculate the three-axis rotational inertia of the core and system accessories respectively, where m is the mass of the particle and r is the vertical distance from the particle to the rotation axis.

[0020] In step S2, when the core and system accessories are irregular in shape, the mass of the core and system accessories is calculated by summing the masses of all mass elements that make up the object, according to the formula Calculate the mass of the core and system accessories respectively, where m is the mass, ρi is the material density of each mass element, and Vi is the volume of each mass element;

[0021] By summing up the moments of inertia of all the mass elements that make up the object, according to the formula Calculate the three-axis rotational inertia of the core and system accessories respectively.

[0022] In step S3, in the process of establishing the three-dimensional numerical model of the fuel cell module, multiple sub-parts are combined into an overall model through Boolean operations, and minor features in the three-dimensional numerical model are removed.

[0023] In the step S4, a solid model mesh division modeling method is used, and mesh refinement is performed on key stress-bearing components and key stress-bearing positions during division.

[0024] In step S5, it is necessary to set material properties, apply loads and contacts, establish mass points and property settings, and establish connections between mass points and constraint points.

[0025] In step S5, the elastic units in the three-dimensional numerical model are connected using a spring model.

[0026] The fuel cell stack vibration and impact simulation analysis method of the present invention can reduce the amount of calculation in the fuel cell stack vibration and impact simulation analysis by simplifying the model of the fuel cell stack packaging assembly and the shell, and the equivalent of the mass point effect of the core and system accessories, and at the same time obtain relatively accurate numerical simulation results, providing a theoretical basis and data support for the structural optimization and material selection of the fuel cell stack packaging assembly. In addition, the adverse effects of vibration and impact on the fuel cell stack are reduced, and the reliability and durability of the fuel cell stack are improved. At the same time, the numerical simulation analysis proofing machine proofing test can be carried out in the early stage of the design, which greatly shortens the research and development cycle and is conducive to the rapid iteration of the fuel cell stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a flow chart of the fuel cell stack vibration impact simulation analysis method of the present invention;

[0028] Figure 2 It is a model of the fuel system and its components;

[0029] Figure 3 It is the battery stack packaging component model;

[0030] Figure 4 It is a schematic diagram of the position of the fuel cell core;

[0031] Figure 5 It is an example of the original digital model of the battery stack packaging component;

[0032] Figure 6This is an example of a simplified model for simulation of a battery stack packaging component;

[0033] The marks in the above figures are: 1. Fuel cell stack; 2. System accessories; 3. Pipes and wiring harnesses; 11. Fuel cell stack packaging assembly shell; 12. Fuel cell stack packaging assembly end plate; 13. Fuel cell stack core; 121. Fuel cell stack packaging assembly threaded hole; 122. Fuel cell stack packaging assembly fillet; 123. Fuel cell stack packaging assembly optimized threaded hole; 124. Fuel cell stack packaging assembly optimized fillet. DETAILED DESCRIPTION

[0034] The specific implementation methods of the present invention are further explained in detail below by describing the embodiments with reference to the accompanying drawings, with the aim of helping those skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solution of the present invention and facilitating its implementation.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly connected by technicians in the technical field to which the present invention belongs. The terminology used in the specification of the present invention is for the purpose of describing specific embodiments and is not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0036] In order to solve the problem that the simulation of the fuel cell core in the prior art does not consider the coupling effect at the system level, the simulation results cannot provide a basis for judging the structural strength from top to bottom; and when considering the influence of the core and system accessories on the package, due to the cross-scale structure, the number of grids in the calculation is huge, the computing power requirements are high and the calculation cycle is long, which has a great impact on the product development cycle, and the calculation convergence and calculation accuracy are also problematic. Thus, a vibration impact simulation analysis method with accurate accuracy and feasible calculation is provided.

[0037] like Figure 1 As shown, a fuel cell stack vibration impact simulation analysis method provided by the present invention comprises the following steps:

[0038] S1. Determine vibration and impact conditions;

[0039] S2. Calculation of the fuel cell stack core mass, system auxiliary parts mass and three-axis rotational inertia;

[0040] S3, simplified processing of three-dimensional numerical model;

[0041] S4, pre-processing grid division;

[0042] S5, solution setting;

[0043] S6. Post-processing of results.

[0044] In the above step S1, the impact test method used is: applying a half-sine shock wave with an acceleration value of 25-30g to the fuel cell module, with a pulse time of Nms. The test will be carried out in five directions of ±x, ±y and +z, and the number of impacts in each direction is M times.

[0045] In the above step S1, N is 5-7, and M is 5-7.

[0046] In the above step S2, when the core and system auxiliary parts have regular shapes, the masses of the core and system auxiliary parts are calculated respectively according to the formula m=ρV, where m is the mass, ρ is the material density, and V is the volume of the parts;

[0047] According to the formula I = mr 2 Calculate the three-axis rotational inertia of the core and system accessories respectively, where m is the mass of the particle and r is the vertical distance from the particle to the rotation axis.

[0048] In the above step S2, when the core and system accessories are irregular in shape, the mass of the core and system accessories is calculated by summing the masses of all mass elements that make up the object, according to the formula Calculate the mass of the core and system accessories respectively, where m is the mass, ρi is the material density of each mass element, and Vi is the volume of each mass element;

[0049] By summing up the moments of inertia of all the mass elements that make up the object, according to the formula Calculate the three-axis rotational inertia of the core and system accessories respectively.

[0050] In the above step S3, in the process of establishing the three-dimensional numerical model of the fuel cell module, multiple sub-parts are combined into an overall model through Boolean operations, and minor features in the three-dimensional numerical model are removed.

[0051] In the above step S4, a solid model mesh division modeling method is used, and mesh refinement is performed on key force-bearing components and key force-bearing positions during division.

[0052] In the above step S5, it is necessary to set material properties, apply loads and contacts, establish mass points and property settings, and establish connections between mass points and constraint points.

[0053] In the above step S5, the elastic units in the three-dimensional numerical model are connected using a spring model.

[0054] In the present invention, by simplifying the model of the fuel cell stack packaging assembly and the shell, and the equivalence of the mass point effects of the core and system accessories, the amount of calculation during the vibration and impact simulation analysis of the fuel cell stack can be reduced, and at the same time, a more accurate numerical simulation result can be obtained, providing a theoretical basis and data support for the structural optimization and material selection of the fuel cell stack packaging assembly. In turn, the adverse effects of vibration and impact on the fuel cell stack are reduced, and the reliability and durability of the fuel cell stack are improved. At the same time, the numerical simulation analysis proofing machine proofing test can be carried out in the early stage of the design, which greatly shortens the research and development cycle and is conducive to the rapid iteration of the fuel cell stack.

[0055] Example

[0056] like Figure 1 As shown, this embodiment provides a fuel cell stack vibration impact simulation analysis method, comprising the following steps:

[0057] S1. Determine vibration and impact conditions;

[0058] S2. Calculation of the fuel cell stack core mass, system auxiliary parts mass and three-axis rotational inertia;

[0059] S3, simplified processing of three-dimensional numerical model;

[0060] S4, pre-processing grid division;

[0061] S5, solution setting;

[0062] S6. Post-processing of results.

[0063] Specifically, in the above step S1, the vibration and impact test refers to the "2024-04 Safety Requirements for Power Batteries for Electric Vehicles" and combines the characteristics of the fuel cell stack and system to formulate the test method and test parameters, where the vibration and impact are carried out in the order of z-axis, y-axis to x-axis, and the power spectra are shown in Table 1, Table 2 and Table 3 respectively.

[0064] Table 1 z-axis power spectrum

[0065] Frequency Hz <![CDATA[Power Spectral Density (PSD) g 2 / Hz]]> <![CDATA[Power Spectral Density (PSD) (m / s 2 ) 2 / Hz]]> 5 0.05 4.81 10 0.06 5.77 20 0.06 5.77 200 0.0008 0.08 RMS 1.44g 14.13m / s2

[0066] Table 2 y-axis power spectrum

[0067] Frequency Hz <![CDATA[Power Spectral Density (PSD) g 2 / Hz]]> <![CDATA[Power Spectral Density (PSD) (m / s 2 ) 2 / Hz]]> 5 0.04 3.85 20 0.04 3.85 200 0.0008 0.08 RMS 1.23g 12.07m / s2

[0068] Table 3x axis power spectrum

[0069]

[0070]

[0071] In the above step S1, the impact test method used is: applying a half-sine shock wave with an acceleration value of 25-30g to the fuel cell module, with a pulse time of Nms. The test will be carried out in five directions of ±x, ±y and +z, and the number of impacts in each direction is M times.

[0072] In this embodiment, in the above step S1, N is 6 and M is 6.

[0073] In the above step S2, when the battery core has a regular shape, the mass of the core is calculated according to the formula m=ρV, where m is the mass of the core, ρ is the density of the core material, and V is the volume of the core.

[0074] In the above step S2, when the system auxiliary component has a regular shape, the mass of the system auxiliary component is calculated according to the formula m=ρV, where m is the mass of the system auxiliary component, ρ is the material density of the system auxiliary component, and V is the volume of the system auxiliary component.

[0075] In the above step S2, when the core shape is irregular, the calculation of the core mass is processed by summing the masses of all mass elements (masses) constituting the core, according to the formula Calculate the mass of the core, where m is the mass of the core, n is the number of mass elements that make up the core, ρi is the material density of each mass element that makes up the core, and Vi is the volume of each mass element that makes up the core.

[0076] In the above step S2, when the system auxiliary component has an irregular shape, the mass of the system auxiliary component is calculated by summing the masses of all mass elements constituting the system auxiliary component, according to the formula Calculate the mass of the system accessories, where m is the mass of the system accessories, n is the number of mass elements that make up the system accessories, ρi is the material density of each mass element that makes up the system accessories, and Vi is the volume of each mass element that makes up the system accessories.

[0077] In the above step S2, when the battery core has a regular shape, according to the formula I = mr 2 Calculate the three-axis rotational inertia I of the battery core, where m is the mass of the core and r is the vertical distance from the core to the rotation axis.

[0078] In the above step S2, when the system auxiliary component has a regular shape, according to the formula I = mr 2 Calculate the three-axis rotational inertia I of the system auxiliary, where m is the mass of the system auxiliary and r is the vertical distance from the system auxiliary to the rotation axis.

[0079] In the above step S2, when the core shape is irregular, the moment of inertia can be processed by summing the moments of inertia of all mass elements (masses) constituting the core, according to the formula Calculate the three-axis moment of inertia I of the core, where n is the number of mass elements that make up the core, m is the mass of the core mass element, and r is the vertical distance from the core mass element to the rotation axis.

[0080] In the above step S2, when the system auxiliary part has an irregular shape, the moment of inertia can be processed by summing the moments of inertia of all mass elements (mass points) constituting the system auxiliary part, according to the formula Calculate the three-axis rotational inertia I of the system auxiliary, where n is the number of mass elements that make up the system auxiliary, m is the mass of the system auxiliary mass elements, and r is the vertical distance from the system auxiliary mass elements to the rotation axis.

[0081] When the shapes of the core and system accessories are complex, they can be calculated using related functions of 3D software or pre-processing geometry software.

[0082] In the above step S3, the three-dimensional numerical model is simplified, that is, the number of elements of the three-dimensional numerical model is reduced, the hierarchical structure is optimized, and the calculation complexity is reduced. The simplification method is as follows: the key force characteristics of the three-dimensional numerical model are not affected to ensure the accuracy of the simulation results; the simplified model is easy to edit and inherit, so as to facilitate the rapid optimization of the product structure.

[0083] like Figure 2 As shown, the fuel cell module includes a stack packaging assembly, a stack, system accessories, and pipes and wiring harnesses. The stack includes a core. The stack packaging assembly is mainly composed of a shell and an end plate. The core is located inside the shell, and the end plate is fixedly installed at the end of the shell. The system accessories are installed outside the shell.

[0084] The specific operation is as follows: in the above step S3, in the process of establishing the three-dimensional numerical model of the fuel cell module in the simulation software, multiple sub-part models (including the stack packaging assembly model, the stack model, the system auxiliary parts model, and the pipeline and wiring harness model) are merged through Boolean operations to form a preliminary three-dimensional overall model, and then the minor features in the preliminary three-dimensional overall model are removed, and the minor features include chamfers and fillets, and the connection relationship between bolts and threaded holes is simplified to form the final three-dimensional numerical model.

[0085] In the above step S4, the solid model meshing modeling method is used to refine the mesh for key load-bearing components and key load-bearing positions in the three-dimensional numerical model during the division, fully reflecting the main characteristics of the structure and ensuring that the mesh can accurately express the geometric shape and key parts of the structure. According to the stress distribution and the gradient of the calculated data change, the density of the mesh is adjusted to ensure the feasibility of the calculation. Key load-bearing components include bolts. Key load-bearing positions include mass loading points.

[0086] In the above step S5, in the simulation software, it is necessary to set material properties, apply loads and contacts, establish mass points and property settings, and establish connections between mass points and constraint points.

[0087] According to the actual selection of materials for various components in the fuel cell stack, such as the stack packaging assembly and the stack core, material properties are assigned. The material properties can be obtained through relevant experimental tests, and for commonly used materials, they can also be obtained by looking up relevant information.

[0088] Due to the complexity of the structure and the primary and secondary relationship of the solution objectives, the fuel cell core and system accessories can be loaded onto the shell using mass points, coupled to the model force area through remote points, and the external load can be loaded onto the remote points. The elastic unit connection in the fuel cell packaging assembly can be simplified to a spring connection, and its stiffness is specified; the pipeline and wiring harness are ignored for the moment because they are relatively light relative to the system. In the above way, the calculation model can be simplified.

[0089] In the above step S6, post-processing: obtaining the main mechanical responses of the stack packaging components such as stress response, displacement, deformation, etc., and evaluating the structural reliability.

[0090] The post-processing results can also be used as a basis for structural optimization, and iterated until the structure fully meets functional requirements.

[0091] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A fuel cell stack vibration and impact simulation analysis method, characterized in that: Includes steps: S1. Determine vibration and impact conditions; S2. Calculation of the fuel cell stack core mass, system auxiliary parts mass and three-axis rotational inertia; S3, simplified processing of three-dimensional numerical model; S4, pre-processing grid division; S5, solution setting; S6. Post-processing of results.

2. The fuel cell stack vibration impact simulation analysis method according to claim 1, characterized in that: In step S1, the impact test method used is: applying a half-sine shock wave with an acceleration value of 25-30g and a pulse time of Nms to the fuel cell module. The test will be carried out in five directions of ±x, ±y and +z, and the number of impacts in each direction is M times.

3. The fuel cell stack vibration impact simulation analysis method according to claim 2, characterized in that: In the step S1, N is 5-7, and M is 5-7.

4. The fuel cell stack vibration and impact simulation analysis method according to any one of claims 1 to 3, characterized in that: In step S2, when the core and system auxiliary parts have regular shapes, the masses of the core and system auxiliary parts are calculated according to the formula m=ρV, where m is the mass, ρ is the material density, and V is the volume of the parts; According to the formula I = mr 2 Calculate the three-axis rotational inertia of the core and system accessories respectively, where m is the mass of the particle and r is the vertical distance from the particle to the rotation axis.

5. The fuel cell stack vibration and impact simulation analysis method according to any one of claims 1 to 3, characterized in that: In step S2, when the core and system accessories are irregular in shape, the mass of the core and system accessories is calculated by summing the masses of all mass elements that make up the object, according to the formula Calculate the mass of the core and system accessories respectively, where m is the mass, ρi is the material density of each mass element, and Vi is the volume of each mass element; By summing up the moments of inertia of all the mass elements that make up the object, according to the formula Calculate the three-axis rotational inertia of the core and system accessories respectively.

6. The fuel cell stack vibration and impact simulation analysis method according to any one of claims 1 to 5, characterized in that: In step S3, in the process of establishing the three-dimensional numerical model of the fuel cell module, multiple sub-parts are combined into an overall model through Boolean operations, and minor features in the three-dimensional numerical model are removed.

7. The fuel cell stack vibration and impact simulation analysis method according to any one of claims 1 to 6, characterized in that: In the step S4, a solid model mesh division modeling method is used, and mesh refinement is performed on key stress-bearing components and key stress-bearing positions during division.

8. The fuel cell stack vibration and impact simulation analysis method according to any one of claims 1 to 6, characterized in that: In step S5, it is necessary to set material properties, apply loads and contacts, establish mass points and property settings, and establish connections between mass points and constraint points.

9. The fuel cell stack vibration impact simulation analysis method according to claim 8, characterized in that: In step S5, the elastic units in the three-dimensional numerical model are connected using a spring model.

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