ANSYS-based vehicle low-temperature prestress modal analysis system and method

Abstract

The invention relates to the technical field of vehicle engineering, in particular to a vehicle low-temperature prestress modal analysis system and method based on ANSYS. Finite element modeling is carried out on a vehicle, and the calculation process is planned. On the basis of ANSYS finite element analysis software, a Pre-Stress Model combination module is designed and constructed to research the overall inherent frequency of a certain type of vehicle under the working condition of low-temperature prestress, and the Pre-Stress Model combination module comprises a project A (a geometric structure module), a project B (a steady-state thermal analysis module), a project C (a static structure analysis module) and a project D (a modal analysis module); the inherent frequency of the whole vehicle under the working condition of low-temperature prestress is researched through the combined module, and researchers can be helped to avoid the resonance phenomenon or vibrate at a specific frequency during structural design.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle engineering, and in particular to a vehicle low-temperature prestressed modal analysis system and method based on ANSYS. Background Art

[0002] In our daily life, the emergence of cars has not only changed our way of traveling, but also greatly affected our living habits, social structure and economic development. The harsh natural environment makes the vehicle structure very prone to brittle fracture in a low temperature environment. This is mainly due to the change in the mechanical properties of the vehicle materials under low temperature conditions, which causes the ductility of the metal / rubber materials to be lost, and the prestress inside the material reaches the critical point. In addition, the influence of factors such as non-directional vibration causes the body structure to crack, resonate or even break under the influence of deformation and vibration, and cannot provide solid and reliable travel protection for drivers and passengers.

[0003] At present, the existing technical means require higher costs and more personnel to conduct vibration, fracture and low-temperature tests on vehicle body structures, which seriously affects the development of my country's automobile industry technology. Summary of the invention

[0004] In view of this, the present invention provides a vehicle low-temperature prestressed modal analysis system and method based on ANSYS, which can help researchers determine the natural frequency and vibration mode of the vehicle structure by simulating the total deformation and stress-strain distribution of the vehicle body structure under low-temperature environment excitation and different modal frequencies, provide a basis for vehicle design and optimization, and improve the adaptability and reliability of the vehicle in low-temperature environments.

[0005] To achieve the above-mentioned object, the present invention provides a vehicle low-temperature prestressed modal analysis system based on ANSYS, including a prestressed modal analysis combination module, three-dimensional modeling software and a model analysis tree;

[0006] The prestressed modal analysis combined module is used to study the natural frequency of a certain type of vehicle under low-temperature prestressed working conditions; the three-dimensional modeling software performs finite element modeling on a certain type of vehicle and plans the simulation calculation process; the model analysis tree is used to generate a mesh model.

[0007] Wherein, the low temperature prestressed modal analysis combined module includes a geometric structure module, a steady-state thermal analysis module, a static structure analysis module and a modal analysis module;

[0008] The geometry module is used to import the vehicle finite element model obtained by finite element modeling and generate a model file in Geometry;

[0009] The steady-state thermal analysis module is used to import the model file generated by Geometry, add the material library and set the model material parameter properties;

[0010] Modify the mesh parameters based on the mesh options in the model analysis tree operation flow chart, set the mesh size correlation to optimal, and use the default settings for the rest; among them, select the Run calculation command based on the equation solved by the steady-state thermal analysis module in the model analysis tree, and perform post-processing operations after the calculation is completed to obtain the temperature load stress of a certain type of vehicle under low-temperature environment excitation;

[0011] The static structural analysis module is used to import the temperature load stress results of a certain type of vehicle in the steady-state thermal analysis module, add remote displacement, keep the solid domain temperature at the set temperature, and solve the static structural analysis results under the influence of prestress, that is, the total deformation of a certain type of vehicle under low-temperature excitation; wherein, the temperature load stress results are imported in a model-associated manner;

[0012] The modal analysis module is used to import the static structural analysis results under the influence of cryogenic prestressing and set the modal order to study the corresponding modal total deformation of a certain type of vehicle under low-temperature environment excitation.

[0013] Among them, CREO three-dimensional modeling software is used to perform finite element modeling on a certain type of vehicle to obtain a vehicle finite element model.

[0014] The model material parameter attribute settings include: the body structure is set to structural steel, and the internal lining, gasket and tire are set to rubber-based composite materials.

[0015] Among them, the steady-state thermal analysis module solves the low-temperature solid domain, sets the temperature of the entire vehicle details to -40°C, and completes the addition of a heat load; under normal operating conditions, the solid domain will generate steady-state temperature stress under the excitation of the low-temperature environment, and the steady-state thermal analysis follows the general equations of steady-state thermodynamics analysis.

[0016] The present invention also provides a vehicle low-temperature prestress modal analysis method based on ANSYS, which is implemented based on the system of the present invention and includes the following steps:

[0017] Model a certain type of vehicle, obtain the vehicle finite element model, and plan the simulation calculation process;

[0018] Design prestressed modal analysis combined module;

[0019] Import the created vehicle finite element model into the cryogenic prestressed modal analysis combined module;

[0020] Based on the general equation of steady-state thermodynamic analysis, select the Run calculation command in the model analysis tree, and perform post-processing operations after the calculation is completed to obtain the temperature load stress of a certain type of vehicle under low-temperature environment excitation;

[0021] Among them, the prestressed modal analysis is understood as a function eigenvalue solution problem, and its related dynamic motion equations are set; the stiffness matrix is ​​a constant;

[0022] Substituting the free vibration form of a certain type of vehicle body structure into the related dynamic motion equation to obtain the characteristic equation;

[0023] Based on the characteristic equation, select the Run calculation command in the model analysis tree, and perform post-processing operations after the calculation is completed to obtain the sixth-order modal total deformation of a certain type of vehicle under low-temperature environment excitation.

[0024] Among them, the design includes a prestressed modal analysis combination module including a geometric structure module, a steady-state thermal analysis module, a static structure analysis module and a modal analysis module;

[0025] The specific process of importing the created vehicle finite element model into the prestressed modal analysis combined module is as follows:

[0026] Import the created vehicle finite element model into the geometry module and generate the model file in Geometry;

[0027] Import the generated model file into the steady-state thermal analysis module, add the material library and set the model material parameter properties. The body structure is set to structural steel, and the internal lining, gasket and tire are set to rubber-based composite materials.

[0028] Modify the mesh parameters based on the mesh options in the model analysis tree operation flow chart, set the mesh size correlation to excellent, and use the default settings for the rest, generate a mesh model, and check the mesh quality;

[0029] Use the steady-state thermal analysis module to solve the low-temperature solid domain, set the temperature of the entire vehicle details to -40°C, and complete the addition of a heat load;

[0030] The temperature load stress results of a certain type of vehicle in the steady-state thermal analysis module are imported into the static structural analysis module through model association, and remote displacement is added. The solid domain temperature is kept at -40°C, and the static structural analysis results under the influence of prestress are obtained, that is, the total deformation of a certain type of vehicle under low-temperature excitation.

[0031] The static structural analysis results under the influence of prestress are imported into the modal analysis module, and the modal order is set to 6 to study the sixth-order modal total deformation of a certain type of vehicle under low-temperature environment excitation.

[0032] Among them, the low-temperature prestressed modal numerical analysis results are evaluated based on the sixth-order modal total deformation of a certain type of vehicle under low-temperature environment excitation.

[0033] Beneficial effects:

[0034] 1. The prestressed modal analysis system of the present invention performs finite element modeling for a certain type of vehicle and plans the calculation process. Based on the ANSYS finite element analysis software, a Pre-Stress Model combination module is designed and constructed to study the natural frequency of a certain type of vehicle under low-temperature prestressed working conditions. The Pre-Stress Model combination module of the present invention includes the creation of Project A (geometric structure module), Project B (steady-state thermal analysis module), Project C (static structural analysis module) and Project D (modal analysis module); by studying the natural frequency of the vehicle as a whole under prestressed working conditions through the combination module, it can help researchers avoid resonance during structural design or make the vehicle vibrate at a specific frequency, and it can also take into account the impact of the performance changes of these materials (metals, rubbers) in low-temperature environments on the rigidity of the vehicle body, thereby more accurately evaluating the structural response of the vehicle.

[0035] 2. Applying the numerical analysis system adopted in the present invention to the structural design of vehicles is more in line with reality and has the characteristics common to all vehicles. It provides technical support for solving problems such as cracking, resonance and even fracture of the vehicle body structure caused by factors such as low temperature and non-directional vibration, and provides solid and reliable travel protection for drivers and passengers.

[0036] 3. The prestress modal analysis method under low-temperature excitation conditions of the present invention is based on ANSYS finite element analysis software, and a Pre-Stress Model combination module is designed to study the natural frequency of a certain type of vehicle under low-temperature prestress conditions. First, a certain type of vehicle model is imported into the geometric structure module in the Pre-Stress Model combination module, and the geometric model is imported into the steady-state thermal analysis module through module association and the low-temperature condition is set to obtain the steady-state prestress of the armored vehicle under low-temperature load; secondly, the obtained steady-state thermal analysis results are imported into the static structure analysis module to study the influence of the vehicle deformation and stress distribution due to its own weight distribution (the vehicle body itself, the engine, the integrated transmission box, etc.) under low-temperature environment excitation; finally, the vehicle body structure after structural mechanics numerical analysis is imported into the modal analysis module, and the sixth-order modal total deformation of the vehicle under low-temperature environment excitation is studied based on the analysis results of the static structure analysis module to better evaluate its performance under low-temperature environment.

[0037] 4. The method of the present invention can help researchers avoid resonance or vibration at a specific frequency during structural design, predict the static and dynamic responses of the vehicle under low-temperature excitation conditions, and identify the weak links and potential problems of the vehicle structure, thereby optimizing the vehicle structure and improving its performance in a low-temperature environment, providing solid and reliable travel protection for drivers and passengers. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic diagram of the Pre-Stress Model combined module used in the system of the present invention.

[0039] Figure 2 It is a schematic diagram of the vehicle finite element model of the present invention.

[0040] Figure 3 It is a flow chart of the model analysis tree operation of the present invention.

[0041] Figure 4 It is a schematic diagram of the vehicle grid effect of the present invention.

[0042] Figure 5 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0043] The present invention is described in detail below with reference to the accompanying drawings and embodiments, taking a certain type of vehicle as an example for analysis.

[0044] Applying the numerical analysis system and method adopted in the present invention to the structural design of a certain type of vehicle can be more in line with reality and have characteristics common to all vehicles. It can provide technical support for solving problems such as cracking, resonance and even fracture of the vehicle body structure caused by factors such as low temperature and non-directional vibration, guide the design work of designers, and provide solid and reliable travel protection for drivers and passengers.

[0045] The system of the present invention comprises a prestressed modal analysis combined module (Pre-Stress Model), three-dimensional modeling software and a model analysis tree.

[0046] Prestressed modal analysis module Figure 1 As shown, it is used to study the natural frequency of a certain type of vehicle under low-temperature prestressing conditions, including a geometric structure module (project A), a steady-state thermal analysis module (project B), a static structural analysis module (project C) and a modal analysis module (project D).

[0047] In this embodiment, the three-dimensional modeling software performs finite element modeling on a certain type of vehicle and plans the simulation calculation process. Preferably, the CREO three-dimensional modeling software is used to perform finite element modeling on a certain type of vehicle to obtain a finite element model of the vehicle. The finite element model of a certain type of vehicle in this embodiment is as follows: Figure 2shown.

[0048] The geometry module (project A) is used to import the vehicle finite element model obtained by finite element modeling and generate a model file in Geometry;

[0049] The steady-state thermal analysis module is used to import the model file generated by Geometry, add the material library and set the model material parameter attributes; in this embodiment, the model material parameter attribute settings include: the body structure is set to structural steel, the internal lining, gasket and tire are set to rubber-based composite materials;

[0050] Among them, the steady-state thermal analysis module solves the low-temperature solid domain (a certain type of vehicle), sets the temperature of the entire vehicle details to -40°C, and completes the addition of a heat load; under normal working conditions, the solid domain will generate steady-state temperature stress under the excitation of the low-temperature environment. The steady-state thermal analysis mainly follows the general equation of steady-state thermodynamic analysis:

[0051] [K]{I}={Q} (1)

[0052] Where [K] is the conduction matrix, including thermal, convection, and radiation coefficients; {I} is the node temperature vector; and {Q} is the node heat flux vector, including heat generation.

[0053] The model analysis tree is used to generate a grid model. Specifically, based on the model analysis tree operation flow chart (such as Figure 3 Modify the mesh parameters by using the mesh options in the grid options as shown in the figure, set the correlation of the mesh size to optimal, and use the default settings for the rest. The generated mesh model is as follows Figure 4 As shown;

[0054] Among them, in the model analysis tree, based on the equation solved by the steady-state thermal analysis module, select the Run calculation command, and perform post-processing operations after the calculation is completed to obtain the temperature load stress of a certain type of vehicle under low-temperature environment excitation.

[0055] The static structural analysis module is used to import the temperature load stress results of a certain type of vehicle in the steady-state thermal analysis module, add remote displacement, keep the temperature of the low-temperature solid domain at -40°C, and solve the static structural analysis results under the influence of low-temperature prestress, that is, the total deformation and stress distribution of the vehicle under low-temperature excitation; wherein, the temperature load stress results are imported in a model-associated manner.

[0056] The modal analysis module is used to import the static structural analysis results under the influence of prestress and set the modal order to 6 to study the sixth-order modal total deformation of a certain type of armored vehicle under low-temperature environment excitation.

[0057] Among them, prestressed modal analysis can be understood as a function eigenvalue solution problem, and its related dynamic motion equation can be set as:

[0058] [M](x")+[k](x)=(0) (2)

[0059] The free vibration form of a certain type of vehicle body structure is simple harmonic vibration, that is, the displacement is a sinusoidal function:

[0060] x=xsin(ωt) (3)

[0061] It is important to note that the stiffness matrix [k] must be a constant. This is mainly to limit the strain and stress of the body structure to be caused by the behavior of elastic materials to meet the constraints of low temperature, non-directional vibration, etc. At the same time, the applied external load cannot affect the structural stiffness;

[0062] Therefore, substituting formula (3) into formula (2) yields:

[0063] ([k]-ω 2 [M]){x}={0} (4)

[0064] In formula (4), the characteristic value of the equation is ω i 2 , its square root ω i is the required self-oscillation circular frequency, and the self-oscillation frequency is

[0065] Eigenvalue ω i The corresponding eigenvector {x i} is the natural frequency The corresponding vibration mode of

[0066] In the model analysis tree, based on the characteristic equation in formula (4), select the Run calculation command until the calculation is completed and perform post-processing operations to obtain the sixth-order modal total deformation of a certain type of vehicle under low-temperature environment excitation.

[0067] The vehicle prestressed modal analysis method of the present invention is based on ANSYS, and is a prestressed modal numerical analysis method under low temperature environment excitation based on the invention system. Figure 5 The schematic diagram of the process of the present invention is as follows:

[0068] Use CREO 3D modeling software to model a certain type of vehicle, obtain the finite element model of the vehicle, and plan the simulation calculation process.

[0069] Design a prestressed modal analysis combined module (Pre-Stress Model) including a geometric structure module (Project A), a steady-state thermal analysis module (Project B), a static structural analysis module (Project C) and a modal analysis module (Project D);

[0070] Import the created vehicle finite element model into the geometry module (Project A) and generate the model file in Geometry;

[0071] Import the generated model file into the steady-state thermal analysis module, add the material library and set the model material parameter properties, where the body structure is set to structural steel and the internal lining is set to rubber-based composite material;

[0072] Based on the mesh option in the model analysis tree operation flow chart, modify the mesh parameters, set the mesh size correlation to excellent, and use the default settings for the rest. Generate a mesh model and check the mesh quality. The mesh distortion should be less than 0.1 to meet the calculation accuracy. Among them, ANSYS finite element analysis software is used to describe the various components of the airborne vehicle in detail, and the corresponding finite element mesh is established based on information such as material properties and connection methods. Mesh division principle: For the body structure with a steel plate thickness much smaller than the length and width, two-dimensional surface units are used for finite element modeling, and the mesh unit size is set to 20mmx20mm; for complex structures such as the balance elbow mounting bracket and the transmission box mounting bracket, three-dimensional meshes are used for division, and the mesh unit size is set to 20mmx20mmx20mm.

[0073] The steady-state thermal analysis module is used to solve the low-temperature solid domain (a certain type of vehicle), and the temperature of the entire vehicle details is set to -40°C to complete the addition of a heat load. Under normal working conditions, the solid domain will generate steady-state temperature stress under the excitation of the low-temperature environment. The steady-state thermal analysis mainly follows the general equation of steady-state thermodynamic analysis:

[0074] [K]{I}={Q} (1)

[0075] Where [K] is the conduction matrix, including the thermal coefficient, convection coefficient, and radiation coefficient; {I} is the node temperature vector; {Q} is the node heat flux vector, including heat generation;

[0076] Based on the general equation of steady-state thermodynamic analysis, select the Run calculation command in the model analysis tree, and perform post-processing operations after the calculation is completed to obtain the temperature load stress of the vehicle under low-temperature environment excitation;

[0077] The temperature load stress results of the vehicle in the steady-state thermal analysis module are imported into the static structural analysis module through model association, and remote displacement is added. The temperature of the low-temperature solid domain is kept at -40°C, and the static structural analysis results under the influence of prestress are obtained, that is, the total deformation and stress distribution of the vehicle under low-temperature excitation;

[0078] Import the static structural analysis results under the influence of prestress into the modal analysis module, and set the modal order to 6 to study the sixth-order modal total deformation of the vehicle under low-temperature environment excitation;

[0079] Among them, prestressed modal analysis can be understood as a function eigenvalue solution problem, and its related dynamic motion equation can be set as:

[0080] [M](x")+[k](x)=(0) (2)

[0081] The free vibration form of the vehicle body structure is simple harmonic vibration, that is, the displacement is a sinusoidal function:

[0082] x=xsin(ωt) (3)

[0083] It is important to note that the stiffness matrix [k] must be a constant. This is mainly to limit the strain and stress of the body structure to be caused by the behavior of elastic materials, so as to meet the limiting conditions such as low temperature and non-directional vibration; at the same time, the applied external load cannot affect the stiffness performance of the structure itself, so that it is only affected by the low temperature prestress;

[0084] Therefore, substituting formula (3) into formula (2) yields:

[0085] ([k]-ω 2 [M]){x}={0} (4)

[0086] In formula (4), the characteristic value of the equation is ω i 2 , its square root ω i is the required self-oscillation circular frequency, and the self-oscillation frequency is

[0087] Eigenvalue ω i The corresponding eigenvector {x i} is the natural frequency The corresponding vibration mode of

[0088] Based on the above characteristic equation, select the Run calculation command in the model analysis tree, and perform post-processing operations after the calculation is completed to obtain the sixth-order modal total deformation of the vehicle under low-temperature environment excitation.

[0089] Furthermore, the low-temperature prestressed modal numerical analysis results can be evaluated based on the sixth-order modal total deformation of the vehicle under low-temperature environmental excitation.

[0090] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. The vehicle low temperature prestressed modal analysis system based on ANSYS is characterized by: Includes prestressed modal analysis combined module, 3D modeling software and model analysis tree; The prestressed modal analysis combined module is used to study the natural frequency of a certain type of vehicle under low-temperature prestressed working conditions; the three-dimensional modeling software performs finite element modeling on a certain type of vehicle and plans the simulation calculation process; the model analysis tree is used to generate a mesh model.

2. The system according to claim 1, characterized in that The low-temperature prestressed modal analysis combined module includes a geometric structure module, a steady-state thermal analysis module, a static structure analysis module and a modal analysis module; The geometry module is used to import the vehicle finite element model obtained by finite element modeling and generate a model file in Geometry; The steady-state thermal analysis module is used to import the model file generated by Geometry, add the material library and set the model material parameter properties; Modify the mesh parameters based on the mesh options in the model analysis tree operation flow chart, set the mesh size correlation to optimal, and use the default settings for the rest; among them, select the Runcalculation command based on the equation solved by the steady-state thermal analysis module in the model analysis tree, and perform post-processing operations after the calculation is completed to obtain the temperature load stress of a certain type of vehicle under low-temperature environment excitation; The static structural analysis module is used to import the temperature load stress results of a certain type of vehicle in the steady-state thermal analysis module, add remote displacement, keep the solid domain temperature at the set temperature, and solve the static structural analysis results under the influence of prestress, that is, the total deformation of a certain type of vehicle under low-temperature excitation; wherein, the temperature load stress results are imported in a model-associated manner; The modal analysis module is used to import the static structural analysis results under the influence of cryogenic prestressing and set the modal order to study the corresponding modal total deformation of a certain type of vehicle under low-temperature environment excitation.

3. The system according to claim 1 or 2, characterized in that: The CREO three-dimensional modeling software is used to perform finite element modeling on a certain type of vehicle to obtain a vehicle finite element model.

4. The system according to claim 2, characterized in that The model material parameter property settings include: the body structure is set to structural steel, and the internal lining, gasket and tire are set to rubber-based composite materials.

5. The system according to claim 2, characterized in that The steady-state thermal analysis module solves the low-temperature solid domain, sets the temperature of the entire vehicle details to -40°C, and completes the addition of a heat load; under normal operating conditions, the solid domain will generate steady-state temperature stress under the excitation of the low-temperature environment, and the steady-state thermal analysis follows the general equations of steady-state thermodynamics analysis.

6. The vehicle low temperature prestress modal analysis method based on ANSYS is characterized by: The system according to any one of claims 1 to 5 is implemented, comprising the following steps: Model a certain type of vehicle, obtain the vehicle finite element model, and plan the simulation calculation process; Design prestressed modal analysis combined module; Import the created vehicle finite element model into the cryogenic prestressed modal analysis combined module; Based on the general equation of steady-state thermodynamic analysis, select the Run calculation command in the model analysis tree, and perform post-processing operations after the calculation is completed to obtain the temperature load stress of a certain type of vehicle under low-temperature environment excitation; Among them, the prestressed modal analysis is understood as a function eigenvalue solution problem, and its related dynamic motion equations are set; the stiffness matrix is ​​a constant; Substituting the free vibration form of a certain type of vehicle body structure into the related dynamic motion equation to obtain the characteristic equation; Based on the characteristic equation, select the Run calculation command in the model analysis tree, and perform post-processing operations after the calculation is completed to obtain the sixth-order modal total deformation of a certain type of vehicle under low-temperature environment excitation.

7. The method according to claim 6, characterized in that Design a prestressed modal analysis combination module including a geometric structure module, a steady-state thermal analysis module, a static structural analysis module, and a modal analysis module; The specific process of importing the created vehicle finite element model into the prestressed modal analysis combined module is as follows: Import the created vehicle finite element model into the geometry module and generate the model file in Geometry; Import the generated model file into the steady-state thermal analysis module, add the material library and set the model material parameter properties. The body structure is set to structural steel, and the internal lining, gasket and tire are set to rubber-based composite materials. Modify the mesh parameters based on the mesh options in the model analysis tree operation flow chart, set the mesh size correlation to excellent, and use the default settings for the rest, generate a mesh model, and check the mesh quality; Use the steady-state thermal analysis module to solve the low-temperature solid domain, set the temperature of the entire vehicle details to -40°C, and complete the addition of a heat load; The temperature load stress results of a certain type of vehicle in the steady-state thermal analysis module are imported into the static structural analysis module through model association, and remote displacement is added. The solid domain temperature is kept at -40°C, and the static structural analysis results under the influence of prestress are obtained, that is, the total deformation of a certain type of vehicle under low-temperature excitation. The static structural analysis results under the influence of prestress are imported into the modal analysis module, and the modal order is set to 6 to study the sixth-order modal total deformation of a certain type of vehicle under low-temperature environment excitation.

8. The method according to claim 6 or 7, characterized in that According to the sixth-order modal total deformation of a certain type of vehicle under low-temperature environment excitation, the low-temperature prestressed modal numerical analysis results are evaluated.

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