Air spring instability condition analysis method

Abstract

The invention relates to an air spring instability condition analysis method. The method comprises the following steps: preparing a model; pre-processing components contained in the model; submitting, analyzing and solving; and post-processing the calculation result. According to the invention, the working condition of continuous inflation and instability of the air spring at the pull-down limit position is realized, and the actual working condition of the air spring is simulated; when the mechanism of instability of the air spring at the pull-down limit position is researched, the parameters of the established model are easy to modify, and related calculation and analysis can be quickly carried out; the established model can accurately describe the force and displacement characteristics of the air spring in the process of moving to the pull-down limit position. And reference is provided for engineering design.

Description

Technical Field

[0001] This invention relates to the field of air spring instability simulation analysis technology, specifically to a method for analyzing air spring instability conditions. Background Technology

[0002] When a car equipped with air springs travels over potholes or is lifted for maintenance, the car wheels are in a downward-jumping state due to their own weight. If the sensor response is slow or the height of the air spring is misidentified, it may generate an incorrect command that causes the ASU to continuously inflate the air spring. This can cause the internal air pressure of the air spring to exceed its limit, resulting in bending and failure. This is referred to as the "instability condition" in this article.

[0003] With the rapid development of technology, society's requirements for automotive driving comfort and safety are constantly increasing. As an elastic element in automotive suspension, the reliability of air springs has a significant impact on passenger driving comfort and safety. In some extreme conditions, such as when a car drives over continuous deep potholes or is rapidly lifted, a severe imbalance may occur between the internal air pressure of the air spring and the load, leading to air spring instability.

[0004] Currently, there is limited research on air spring instability conditions across various fields, and no simulation models exist to predict their occurrence. This makes it impossible to accurately reconstruct the mechanical processes of instability or precisely describe the force-displacement characteristics of an air spring from normal motion to its pull-down limit and then to instability, hindering research on instability mechanisms and structural optimization. Due to the lack of effective simulation analysis methods, current research on air spring instability conditions largely relies on physical tests (such as passenger car quarter-suspension test bench tests). However, physical tests require repeated setup of test equipment and adjustment of test parameters, which is not only time-consuming and costly but also makes it difficult to quickly conduct comparative studies of instability under different parameters (such as materials, loads, and structural dimensions). This hinders the efficient identification of weak points in air spring instability and restricts the progress of air spring structural optimization and reliability improvement. Summary of the Invention

[0005] To address the problems existing in the prior art, the purpose of this invention is to provide a method for analyzing the instability of air springs, which can simulate the actual instability of air springs, facilitate the prediction of air spring instability, and provide guidance for the optimization of air spring structures.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for analyzing the instability of an air spring, including

[0008] Step 1, Model Preparation: Determine the modeling components used to simulate the instability test of the air spring on the passenger car 1 / 4 suspension test bench, including the rubber airbag, upper cover, piston, guide tube, lower seat, cord, and test fixture;

[0009] Step 2, component preprocessing: Model, assemble, establish contact relationships, define loads, and mesh the modeled components determined in Step 1;

[0010] Step 3, Submit for analysis and solution: Based on the model preprocessed in Step 2, configure the solution control parameters and then perform analysis and calculation;

[0011] Step 4, Post-processing of calculation results: Export and analyze the analysis and calculation results of Step 3 to realize the simulation and mechanism study of air spring instability.

[0012] Furthermore, the modeling in step 2 includes: determining the dimensions of the rubber airbag, top cover, piston, guide tube, lower seat, cord, and test fixture; establishing solid models of each component; creating solid units or shell units that fit each component; and performing chamfering and rounding on the component models.

[0013] Furthermore, the assembly in step 2 includes: defining the material properties, component type, and material orientation of each component model; importing all component models into the assembly interface; adjusting the initial position of each component through rotation and displacement operations; and completing the component assembly.

[0014] Furthermore, the establishment of contact relationships in step 2 includes:

[0015] Step 2.1: Create three analysis steps of type Dynamic-implicit, denoted as Step-1, Step-2 and Step-3 respectively. Define the incremental step type of the three analysis steps as Automatic, with an initial incremental step of 0.01 and a maximum incremental step of 10,000 steps, thereby constructing a dynamic analysis timeframe for the subsequent contact relationship to take effect.

[0016] Step 2.2: Based on the completed assembly model, and using the three analysis steps created in Step 2.1 as the time basis, establish the contact relationships between the components: denote the sealed space formed by the inner layer of the rubber airbag as Int-1, and define its type as a fluid cavity; denote the contact part between the piston and the rubber airbag as Int-2, the contact part between the guide cylinder and the rubber airbag as Int-3, and the contact part between the lower seat and the rubber airbag as Int-4. Int-2, Int-3, and Int-4 are all defined as surface-to-surface contact, and ensure that Int-1, Int-2, Int-3, and Int-4 remain active in the three analysis steps Step-1, Step-2, and Step-3, so that the contact relationships remain effective throughout the entire dynamic analysis process;

[0017] Step 2.3: For the four contact objects Int-1, Int-2, Int-3, and Int-4 defined in Step 2.2, corresponding contact attributes are created respectively: the contact attribute of Int-1 is denoted as IntProp-1, and its type is defined as fluid cavity attribute to match the air pressure transmission characteristics of the fluid cavity; the contact attributes of Int-2, Int-3, and Int-4 are uniformly denoted as IntProp-2, and its type is defined as contact attribute. IntProp-2 is set to have a penalty function type for tangential behavior and hard contact for normal behavior, thereby clarifying the mechanical response rules of surface-to-surface contact, so that the contact objects defined in Step 2.2 have complete mechanical behavior parameters and form a complete contact relationship that can be used for analysis and calculation.

[0018] Furthermore, the load definition in step 2 includes:

[0019] Using fluid cavity Int-1 as the load object, and combining the dynamic analysis steps from Step-1 to Step-3, pneumatic loads are applied in stages: in Step-1, an initial pneumatic load of 0.8 MPa is applied to Int-1 to simulate the normal inflation state of the air spring; in Step-3, a pneumatic load of 1.3 MPa is applied to Int-1 to simulate the overpressure inflation state after the air spring moves to the downward limit position, thereby matching the pneumatic pressure change process of the actual instability condition.

[0020] Using the assembled model as the main load-bearing entity, and based on the determined dynamic analysis timeframe, displacement loads are applied in accordance with the phased pneumatic load application requirements: First, the reference coordinate system for the displacement load is set to the vehicle coordinate system; second, the six degrees of freedom displacement loads of the air spring cover, guide cylinder, piston, and test fixture are all set to 0 to keep the initial installation position unchanged, and only the six degrees of freedom displacement load is applied to the lower seat of the air spring; at the same time, it is ensured that the displacement load is continuously applied in all analysis steps from Step-1 to Step-3 to achieve continuous movement of the air spring from the initial state to the pull-down limit position.

[0021] Furthermore, the mesh generation in step 2 includes:

[0022] The piston and lower seat models use 8-node C3D8R hexahedral elements; the rubber airbag model uses 8-node C3D8H hexahedral elements; the cord model uses 4-node SFM3D4-face elements; the upper cover model uses 4-node C3D10 tetrahedral elements; the guide cylinder model uses 8-node C3D8H hexahedral elements; and the test fixture model uses 8-node C3D8H hexahedral elements.

[0023] Furthermore, the material properties of each component model are as follows: the piston model and the lower seat model are made of a composite material of polyamide 66 and 30% glass fiber, with an elastic modulus Ec = 1 × 10⁻⁶. 4 Pa, Poisson's ratio μ = 0.35; the rubber airbag model uses a hyperelastic material; the cord model uses nylon material with an elastic modulus Ec = 8 × 10⁻⁶. 3 Pa, Poisson's ratio μ = 0.3; the top cover model is made of a composite material of polyamide 66 and 30% glass fiber, with an elastic modulus Ec = 1 × 10⁻⁶. 4 Pa, Poisson's ratio μ=0.35; the guide cylinder model uses aluminum profile material, elastic modulus Ec=7.25×10 4 Pa, Poisson's ratio μ = 0.35; the experimental fixture model uses 45# steel with an elastic modulus Ec = 2.1 × 10⁻⁶. 5 Pa, Poisson's ratio μ = 0.33.

[0024] Furthermore, the hyperelastic constitutive model corresponding to the rubber airbag model is Yeoh, and this hyperelastic model is established by defining the strain energy function W. The strain energy function is represented by three deformation tensor invariant functions I1, I2, and I3, and the tensors are defined by the principal tensor ratios λ1, λ2, and λ3, and their expressions are as follows:

[0025] W = W(I1,I2,I3) (1)

[0026]

[0027] Where I1, I2, and I3 are the first, second, and third tensor invariants, respectively, referring to tensor functions whose values ​​remain unchanged under coordinate transformation; λ1, λ2, and λ3 are the three principal stretch ratios, which are physical quantities describing material deformation;

[0028] The Yeoh model is a third-order polynomial model and introduces a model that is completely dependent on the first tensor invariant I1. The model expression is as follows:

[0029]

[0030] Among them, C ij D represents the material constants related to shear behavior. i J represents the material constant related to volume compressibility. el The elastic volume ratio; μ i and a i It depends on the material properties.

[0031] Furthermore, step 4 involves exporting and analyzing the calculation results, including: exporting the force data of each component under the air spring instability condition, focusing on extracting the force and displacement data of the piston's overall movement process, and comparing this data with the test data of the passenger car 1 / 4 suspension test bench to verify the accuracy of the model.

[0032] Furthermore, the simulation of the air spring instability condition in step 4 includes: through continuous analysis from Step-1 to Step-3, simulating the entire process of the air spring from the initial state to the pull-down limit position, and then to the continuous inflation and instability at the limit position. In Step-3, the air spring reaches the pull-down limit position, and the air pressure load of 1.3MPa simulates the overpressure inflation state under the actual instability condition.

[0033] In summary, the present invention has the following advantages:

[0034] High realism of operating condition simulation: By reproducing the component composition and load conditions of a passenger car 1 / 4 suspension test bench, and combining the ideal gas law and material constitutive model, the actual operating condition of air spring instability due to continuous inflation at the pull-down limit position is accurately reproduced. This solves the problem of lack of simulation of instability operating conditions in existing technologies. The model calculation results are highly consistent with the test bench test data, providing a reliable basis for the study of instability mechanism.

[0035] High flexibility in parameter adjustment: The material properties, mesh parameters, and load conditions of each component can be modified independently during the modeling process without reconstructing the overall model. This allows for rapid comparative analysis of instability conditions under different parameters, significantly improving research efficiency and reducing experimental costs.

[0036] Precise mechanical property description: The rubber airbag adopts the Yeoh hyperelastic model, which can accurately capture the stress-strain relationship under large deformation; the coordinated setting of fluid cavity and surface-to-surface contact in the contact relationship can accurately transmit the air pressure load and the friction and compression between components, ensuring that the model can accurately describe the force-displacement characteristics of the air spring from normal motion to instability, providing accurate mechanical data for structural optimization.

[0037] Significant engineering guidance value: Post-processing can directly obtain the stress distribution and instability critical conditions of each component, identify the weak points of air spring instability, and provide direct guidance for optimizing the material selection, structural design and control strategy of air springs in engineering, thereby improving the comfort and safety of automotive suspension. Attached Figure Description

[0038] Figure 1 This is a flowchart for establishing a method for analyzing the instability of an air spring;

[0039] Figure 2 Schematic diagram of air spring model and test fixture model;

[0040] Figure 3 A schematic diagram defining the local coordinate system for the air spring cord component material;

[0041] Figure 4 A schematic diagram defining the tilt angle of the material for the air spring cord component.

[0042] Figure 5 A schematic diagram defining the surface of the air spring fluid cavity and the reference point;

[0043] Figure 6 A schematic diagram showing the mesh generation of the air spring model and the test fixture model;

[0044] Figure 7 A cloud map showing the simulation results of the air spring instability condition;

[0045] Figure 8 A comparison chart of calculated force and displacement data and experimental data for the overall piston motion under air spring instability conditions; in the chart:

[0046] 3-Piston, 4-Guide cylinder, 5-Rubber airbag, 6-Lower seat, 7-Test fixture, 8-Upper cover. Detailed Implementation

[0047] The present invention will now be described in further detail.

[0048] A method for analyzing the instability of an air spring includes the following steps:

[0049] (1) Model Preparation: This step mainly involves identifying the components included in the analysis method to recreate the instability test of the air spring on a passenger car quarter suspension test bench. For example... Figure 2 As shown, the main components include rubber airbag 5, upper cover 8, piston 3, guide cylinder 4, lower seat 6, cord and test fixture 7, to ensure that the component types are consistent with the actual test components of the passenger car 1 / 4 suspension test bench, and to provide a physical basis for subsequent modeling.

[0050] (2) Preprocessing of the components contained in the model: The preprocessing steps mainly involve modeling and meshing the determined components.

[0051] (3) Submit for analysis and solution: Configure the solution control parameters, select single precision for output precision, and submit the established model for analysis and calculation.

[0052] (4) Post-processing of calculation results: Post-processing of calculation results mainly involves exporting and analyzing the calculation results.

[0053] Specifically, step (2) is as follows:

[0054] Step 1: Based on the determined dimensions of the rubber airbag 5, upper cover 8, piston 3, guide cylinder 4, lower seat 6, cord, and test fixture 7, create each component, then create solid units and shell units, and complete the processing of bevels and fillets. Define the component materials and component types, and assemble all imported components. In this interface, the initial position of the assembled components can be adjusted through rotation and displacement operations. The cord component uses shell units, and the material direction is defined as follows: Figure 3 As shown, axis n corresponds to the local curved surface direction, axis 1 corresponds to the axial direction, and axis 2 corresponds to the radial direction. Based on the cord arrangement, its tilt angle α is set, as follows: Figure 4 As shown.

[0055] Step 2: Create analysis steps Step-1, Step-2, and Step-3, all of which are of type Dynamic-implicit. In the Analysis Steps tab, define the increment step type for the three analysis steps as Automatic, with an initial increment step of 0.01 and a maximum increment step of 10,000.

[0056] Step 3: Establish the contact relationships between the components. The sealed space formed by the inner layer of the rubber airbag is named Int-1, defined as a fluid cavity, and the red node is selected as the reference point for the fluid cavity, as shown below. Figure 5 As shown. The red reference point, besides serving as an identifier for the fluid cavity, can also be used to apply loads to complete inflation or deflation. In this analytical method, the gas inside the air spring is considered an ideal gas, and the ideal gas law is expressed as follows:

[0057]

[0058] Among them, absolute pressure Defined by the following expression:

[0059]

[0060] Where p A Here, p is the ambient air pressure, R is the gauge pressure, θ is the gas constant, and θ is the ambient temperature. Z It is absolute zero.

[0061] The portion of the piston in contact with the rubber airbag is named Int-2, and its type is defined as surface-to-surface contact. The portion of the guide cylinder in contact with the rubber airbag is named Int-3, and its type is defined as surface-to-surface contact. The portion of the lower seat in contact with the rubber airbag is named Int-4, and its type is defined as surface-to-surface contact. These contacts remain active in all analysis steps. After creating the contact relationships, contact properties need to be created. The contact property of Int-1 is named IntProp-1, and its type is fluid cavity. The contact properties of Int-2, Int-3, and Int-4 are named IntProp-2, defined as contact, with tangential behavior defined as a penalty function type, a fixed friction coefficient of 0.05, and normal behavior defined as hard contact.

[0062] Step 4: Define the loads in the analysis process. Apply a pneumatic load of 0.8 MPa to the fluid cavity, as set in Step-1. To bring the air spring to its pull-down limit, the six degrees of freedom displacement loads applied to the air spring cover, guide cylinder, piston, and test fixture are all zero, i.e., they remain stationary in their initial installation positions. Only the lower air spring cover is subjected to a six-degree-of-freedom displacement load. The displacement load magnitudes corresponding to the six degrees of freedom of the lower air spring cover are U1 = -19.7 mm, U2 = -55.9 mm, U3 = -19.4 mm, UR1 = 0.235 rad, UR2 = 0, and UR3 = 0. In Step-3, the air spring has reached its pull-down limit, and a pneumatic load of 1.3 MPa is applied to the fluid cavity to simulate actual working conditions. The reference coordinate system for applying the displacement load is the vehicle coordinate system, with its origin at the vehicle's center of mass, the X-axis pointing in the direction of the vehicle's movement, the Y-axis pointing to the driver's left, and the Z-axis vertically upward.

[0063] After defining the air pressure load and displacement load, mesh generation and mesh element type definition are performed for each component. A schematic diagram of the model after mesh generation is shown below. Figure 6 As shown.

[0064] Step 5: Submit the analysis and calculation. After the calculation is completed, the force conditions of each component of the air spring under the instability condition will be obtained, such as... Figure 7 As shown. The force and displacement data of the piston's overall motion process are output and compared with experimental test data, such as... Figure 8 As shown, the established model is close to the test results of the passenger car 1 / 4 suspension test bench, and the accuracy is good.

[0065] Specifically, the established models include a rubber airbag model, an upper cover model, a piston model, a guide cylinder model, a lower seat model, a cord model, and a test fixture model. Among these, the piston model and the lower seat model are made of a composite material of polyamide 66 and 30% glass fiber, with an elastic modulus of E. c =1×10 4Pa, Poisson's ratio μ = 0.35, and the mesh element type uses 8-node C3D8R hexahedral elements, with a total of 18560 mesh elements.

[0066] Specifically, the rubber airbag model uses a hyperelastic material, and the corresponding hyperelastic constitutive model is Yeoh. This hyperelastic model is established by defining the strain energy function W. The strain energy function is represented by three deformation tensor invariant functions I1, I2, and I3, and the tensors are defined by the principal stretch ratios λ1, λ2, and λ3, as shown in the following expressions:

[0067] W = W(I1,I2,I3) (3)

[0068] I1=λ1 2 +λ2 2 +λ3 2 (4)

[0069] I2=λ1 2 λ2 2 +λ2 2 λ3 2 +λ3 2 λ1 2

[0070] I3=λ1 2 λ2 2 λ3 2

[0071] Where I1, I2, and I3 are the first, second, and third tensor invariants, respectively, referring to tensor functions whose values ​​remain unchanged under coordinate transformation; λ1, λ2, and λ3 are the three principal stretch ratios, which are physical quantities describing material deformation.

[0072] The Yeoh model is a third-order polynomial model and introduces an invariant I1 that is completely dependent on the first tensor. This model can efficiently obtain the upward curvature of the stress-strain curve, and its expression is as follows:

[0073]

[0074] Among them, C ij D represents the material constants related to shear behavior. i J represents the material constant related to volume compressibility. el The elastic volume ratio; μ i and a i Depending on the material properties, the rubber airbag model uses 8-node C3D8H hexahedral elements, with a total of 18,600 mesh elements.

[0075] Specifically, the cord model uses nylon material with a corresponding elastic modulus of E. c=8×10 3 Pa, Poisson's ratio μ = 0.3, and the mesh element type is 4-node SFM3D 4-face element, with a total of 5840 mesh elements.

[0076] Specifically, the top cover model is made of a composite material of polyamide 66 and 30% glass fiber, with an elastic modulus of E. c =1×10 4 Pa, Poisson's ratio μ = 0.35, and the mesh element type is 4-node C3D10 tetrahedral element, with a total of 18360 mesh elements.

[0077] Specifically, the guide tube model is made of aluminum profile material, with a corresponding elastic modulus of E. c =7.25×10 4 Pa, Poisson's ratio μ = 0.35, the mesh element type is 8-node C3D8H hexahedral element, and the total number of meshes is 9120.

[0078] Specifically, the experimental fixture model was made of No. 45 steel, with a corresponding elastic modulus of E. c =2.1×10 5 Pa, Poisson's ratio μ = 0.33, the mesh element type is 8-node C3D8H hexahedral element, and the total number of meshes is 14340.

[0079] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for analyzing the instability of an air spring, characterized in that: include Step 1, Model Preparation: Determine the modeling components used to simulate the instability test of the air spring on the passenger car 1 / 4 suspension test bench, including the rubber airbag, upper cover, piston, guide tube, lower seat, cord, and test fixture; Step 2, component preprocessing: Model, assemble, establish contact relationships, define loads, and mesh the modeled components determined in Step 1; Step 3, Submit for analysis and solution: Based on the model preprocessed in Step 2, configure the solution control parameters and then perform analysis and calculation; Step 4, Post-processing of calculation results: Export and analyze the analysis and calculation results of Step 3 to realize the simulation and mechanism study of air spring instability.

2. The analytical method according to claim 1, characterized in that: The modeling in step 2 includes: determining the dimensions of the rubber airbag, top cover, piston, guide tube, lower seat, cord, and test fixture; establishing solid models of each component; creating solid units or shell units that fit each component; and performing chamfering and rounding on the component models.

3. The analytical method according to claim 2, characterized in that: Step 2 assembly includes: defining the material properties, component type, and material orientation of each component model; importing all component models into the assembly interface; adjusting the initial position of each component through rotation and displacement operations; and completing the component assembly.

4. The analytical method according to claim 1, characterized in that: The establishment of contact relationships in step 2 includes: Step 2.1: Create three analysis steps of type Dynamic-implicit, denoted as Step-1, Step-2 and Step-3 respectively. Define the incremental step type of the three analysis steps as Automatic, with an initial incremental step of 0.01 and a maximum incremental step of 10,000 steps, thereby constructing a dynamic analysis timeframe for the subsequent contact relationship to take effect. Step 2.2: Based on the completed assembly model, and using the three analysis steps created in Step 2.1 as the time basis, establish the contact relationships between the components: denote the sealed space formed by the inner layer of the rubber airbag as Int-1, and define its type as a fluid cavity; denote the contact part between the piston and the rubber airbag as Int-2, the contact part between the guide cylinder and the rubber airbag as Int-3, and the contact part between the lower seat and the rubber airbag as Int-4. Int-2, Int-3, and Int-4 are all defined as surface-to-surface contact, and ensure that Int-1, Int-2, Int-3, and Int-4 remain active in the three analysis steps Step-1, Step-2, and Step-3, so that the contact relationships remain effective throughout the entire dynamic analysis process; Step 2.3: For the four contact objects Int-1, Int-2, Int-3, and Int-4 defined in Step 2.2, corresponding contact attributes are created respectively: the contact attribute of Int-1 is denoted as IntProp-1, and its type is defined as fluid cavity attribute to match the air pressure transmission characteristics of the fluid cavity; the contact attributes of Int-2, Int-3, and Int-4 are uniformly denoted as IntProp-2, and its type is defined as contact attribute. IntProp-2 is set to have a penalty function type for tangential behavior and hard contact for normal behavior, thereby clarifying the mechanical response rules of surface-to-surface contact, so that the contact objects defined in Step 2.2 have complete mechanical behavior parameters and form a complete contact relationship that can be used for analysis and calculation.

5. The analytical method according to claim 4, characterized in that: The load definition in step 2 includes: Using fluid cavity Int-1 as the load object, and combining the dynamic analysis steps from Step-1 to Step-3, pneumatic loads are applied in stages: in Step-1, an initial pneumatic load of 0.8 MPa is applied to Int-1 to simulate the normal inflation state of the air spring; in Step-3, a pneumatic load of 1.3 MPa is applied to Int-1 to simulate the overpressure inflation state after the air spring moves to the downward limit position, thereby matching the pneumatic pressure change process of the actual instability condition. Using the assembled model as the main load-bearing entity, and based on the determined dynamic analysis timeframe, displacement loads are applied in accordance with the phased pneumatic load application requirements: First, the reference coordinate system for the displacement load is set to the vehicle coordinate system; second, the six degrees of freedom displacement loads of the air spring cover, guide cylinder, piston, and test fixture are all set to 0 to keep the initial installation position unchanged, and only the six degrees of freedom displacement load is applied to the lower seat of the air spring; at the same time, it is ensured that the displacement load is continuously applied in all analysis steps from Step-1 to Step-3 to achieve continuous movement of the air spring from the initial state to the pull-down limit position.

6. The analytical method according to claim 1, characterized in that: The mesh generation in step 2 includes: The piston and lower seat models use 8-node C3D8R hexahedral elements; the rubber airbag model uses 8-node C3D8H hexahedral elements; the cord model uses 4-node SFM3D4-face elements; the upper cover model uses 4-node C3D10 tetrahedral elements; the guide cylinder model uses 8-node C3D8H hexahedral elements; and the test fixture model uses 8-node C3D8H hexahedral elements.

7. The analytical method according to claim 3, characterized in that: The material properties of each component model are as follows: the piston model and the lower seat model are made of a composite material of polyamide 66 and 30% glass fiber, with an elastic modulus Ec = 1 × 10⁻⁶. 4 Pa, Poisson's ratio μ = 0.35; the rubber airbag model uses a hyperelastic material; the cord model uses nylon material with an elastic modulus Ec = 8 × 10⁻⁶. 3 Pa, Poisson's ratio μ = 0.3; the top cover model is made of a composite material of polyamide 66 and 30% glass fiber, with an elastic modulus Ec = 1 × 10⁻⁶. 4 Pa, Poisson's ratio μ=0.35; the guide cylinder model uses aluminum profile material, elastic modulus Ec=7.25×10 4 Pa, Poisson's ratio μ=0.35; the experimental fixture model uses No. 45 steel, with an elastic modulus Ec=2.1×105Pa and a Poisson's ratio μ=0.

33.

8. The analytical method according to claim 7, characterized in that: The hyperelastic constitutive model corresponding to the rubber airbag model is Yeoh, and this hyperelastic model is established by defining the strain energy function W. The strain energy function is represented by three deformation tensor invariant functions I1, I2, and I3, and the tensors are defined by the principal tensor ratios λ1, λ2, and λ3. Their expressions are as follows: W = W(I1,I2,I3) (1) I1=λ1 2 +λ2 2 +λ3 2 (2) I2=λ1 2 λ2 2 +λ2 2 λ3 2 +λ3 2 λ1 2 I3=λ1 2 λ2 2 λ3 2 Where I1, I2, and I3 are the first, second, and third tensor invariants, respectively, referring to tensor functions whose values ​​remain unchanged under coordinate transformation; λ1, λ2, and λ3 are the three principal stretch ratios, which are physical quantities describing material deformation; The Yeoh model is a third-order polynomial model and introduces a model that is completely dependent on the first tensor invariant I1. The model expression is as follows: Among them, C ij D represents the material constants related to shear behavior. i J represents the material constant related to volume compressibility. el The elastic volume ratio; μ i and a i It depends on the material properties.

9. The analytical method according to claim 1, characterized in that: Step 4 involves exporting and analyzing the calculation results, including: exporting the force data of each component under the air spring instability condition, focusing on extracting the force and displacement data of the piston's overall movement process, and comparing this data with the test data of the passenger car 1 / 4 suspension test bench to verify the accuracy of the model.

10. The analytical method according to claim 4, characterized in that: Step 4 simulates the instability of the air spring by continuously analyzing from Step-1 to Step-3, simulating the entire process of the air spring from its initial state to the pull-down limit position and then to the limit position where it continues to inflate and become unstable. In Step-3, the air spring reaches the pull-down limit position, and the air pressure load of 1.3MPa simulates the overpressure inflation state under the actual instability condition.

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