Method and system for predicting fatigue life of damper valve system

Abstract

The invention provides a shock absorber valve system fatigue life prediction method and system, and the method comprises the steps: building a shock absorber valve system fatigue life parameterized model through a fluid mechanics and finite element analysis method, and inputting related parameters which affect the damping force as the characteristic variables of the model; the effectiveness of a shock absorber indicator diagram and a damping force rapid verification model is analyzed through simulation, parameters are examined in time, optimization is made, and meanwhile preloading-valve opening-valve closing stress serves as a cycle period; and the vibration damper valve system stress change is used as a single stress cycle of fatigue analysis stress to quickly and efficiently analyze the fatigue life of the vibration damper valve system combination. According to the method for predicting the fatigue life of the valve system, the fatigue life of the damper valve system combination can be rapidly and efficiently analyzed, and simulation and test error precision obtained through a large number of actual measurement benchmarks can be controlled within 10%.

Description

Technical Field

[0001] The present invention relates to the field of vehicle shock absorbers, and particularly to a method and system for predicting the fatigue life of a shock absorber valve system. Background Art

[0002] As a key component of a vehicle suspension system, a shock absorber mainly functions to provide damping force to absorb the impact energy from the ground and rapidly attenuate the vibration of the vehicle body, thereby ensuring the vehicle's handling stability, ride comfort, and safety. The damping force of a shock absorber is generated by the throttling effect of the valve system on the oil. Once the valve system fails, the shock absorber loses its function.

[0003] During the development process of a whole vehicle, the shock absorber valve system undergoes multiple rounds of matching and tuning at different stages. Moreover, there are often multiple different combinations of shock absorber valve systems for different configurations of a vehicle model to achieve an ideal driving experience. In actual engineering, the fatigue life of the valve system is mainly verified through high-speed durability bench tests of shock absorbers. This method has the following problems: 1. The test cycle is long, and it is impossible to timely determine whether the tuned valve system combination meets the durability requirements and make optimization adjustments, which affects the project progress; 2. The test has poor product coverage, and it is difficult to cover all products during the development process due to the limited resources of high-speed durability test equipment; 3. The test cost is high, and the verification cost for a single product exceeds ten thousand yuan.

[0004] In addition, in the prior art, a method for analyzing the valve plate of an electromagnetic valve-controlled damping adjustable shock absorber based on finite element has been proposed. This method conducts valve system performance tests on such an electromagnetic valve-controlled shock absorber, determines the pressure received by the annular valve plate, and performs three-dimensional modeling on the rebound valve and compression valve. Finally, the relationship between the deformation of the rebound valve plate and compression valve plate and the valve plate pressure is obtained to study the force-displacement characteristics of the shock absorber. Although this method establishes a three-dimensional finite model of the valve system, it does not check and correct the accuracy of the model, nor does it analyze the fatigue life of the valve system.

[0005] In summary, how to accurately, efficiently, and at low cost analyze the fatigue life of a shock absorber valve system is of great significance for enterprises to reduce costs, increase efficiency, and enhance competitiveness. Summary of the Invention

[0006] Aiming at the deficiencies in the prior art, the purpose of the present invention is to provide a method and system for predicting the fatigue life of a shock absorber valve system. By establishing a parametric model for the fatigue life of the shock absorber valve system through fluid mechanics and finite element analysis, and quickly verifying the effectiveness of the model by comparing the simulated damping force with the measured damping force. Applying this parametric model and the valve system fatigue analysis method, the fatigue life of the shock absorber valve system combination can be analyzed quickly and efficiently.

[0007] To achieve the above technical effects, the present invention adopts the following technical solutions:

[0008] According to the first aspect of the present invention, a method for predicting the fatigue life of a shock absorber valve system is provided, including the following steps:

[0009] Step 1: Apply fluid mechanics and finite element analysis methods to establish a parametric model for predicting the fatigue life of the shock absorber valve system, and input the parameters affecting the damping force as the characteristic variables of the model. The parameters include A - oil and gas; B - excitation signal; C - friction force signal; D - oil storage cylinder; E - flow valve; F - rebound valve; G - compression valve; H - compensation valve; I - working cylinder. By adjusting the characteristic variables input into the model, analysis models of different shock absorber valve system combinations can be obtained;

[0010] Step 2: Simulate and analyze whether the indicator diagram of the shock absorber in the parametric model for predicting the fatigue life of the shock absorber valve system is full and distortion-free; if the simulated indicator diagram is smooth and full, it indicates that the model has the function of the shock absorber and the next step can be carried out; if the indicator diagram is not full and there is distortion, it is necessary to return to find the reason and debug the parameters;

[0011] Step 3: Simulate and analyze whether the comparison error between the damping force of the shock absorber in the parametric model for predicting the fatigue life of the shock absorber valve system and the measured damping force is less than 10%; if the error is less than 10%, it proves that the model is true and effective and the next step can be carried out; otherwise, the parameters of the model need to be further optimized;

[0012] Step 4: Extract the cyclic stress characteristics of preload - valve opening - valve closing of the shock absorber valve system;

[0013] Step 5: Import a stress cycle of preload - valve opening - valve closing of the shock absorber valve system in Step 4 into FEMFAT software to analyze the fatigue life of the shock absorber valve system combination.

[0014] In this technical solution, the effectiveness of the model can be quickly verified by simulating and analyzing the indicator diagram and damping force of the shock absorber, and the parameters can be reviewed in a timely manner and optimized.

[0015] Optionally, in Step 2 and Step 3, the damping force of the shock absorber is calculated by the following formula:

[0016]

[0017] In the formula: F(t) is the damping force, is the pressure difference between the upper and lower chambers of the working cylinder, is the pressure difference between the lower chamber of the working cylinder and the oil storage chamber, is the pressure of the oil storage chamber, is the leakage pressure, is the external atmospheric pressure, is the piston cross-sectional area, is the connecting rod cross-sectional area, is the leakage area, F f is the frictional force.

[0018] Optionally, step four includes the following specific steps: First, analyze the process of the shock absorber under preload, and obtain the stress of the initial installation state of the shock absorber valve system through the forced displacement load; Second, perform uniform loading on the shock absorber valve system according to the fluid action area for open-valve analysis, and analyze the stress change law during the open-valve process of the shock absorber; Furthermore, perform uniform loading on the shock absorber according to the fluid action area for closed-valve analysis, and analyze the stress change law during the closed-valve process of the shock absorber; Finally, take the preload-open valve-closed valve stress as a cycle period, and regard the stress change of the shock absorber valve system as a single stress cycle of the fatigue analysis stress.

[0019] Optionally, the valve plate in the parametric model for predicting the fatigue life of the shock absorber valve system is divided by solid elements, the basic size of the valve plate mesh is 0.2 mm, there are at least three layers in the thickness direction, and the middle hole of the valve plate is fully constrained.

[0020] Optionally, step five further includes the following steps: Compare the fatigue life calculated by simulation in step five with the measured fatigue to optimize the parametric model for predicting the fatigue life of the shock absorber valve system.

[0021] Optionally, the optimization of the parametric model for predicting the fatigue life of the shock absorber valve system includes adjusting and optimizing the simulation grid, different valve plate loading areas, and valve plate contact forms.

[0022] According to the second aspect of the present invention, there is provided a system for predicting the fatigue life of a shock absorber valve system for implementing the above-mentioned method for predicting the fatigue life of a shock absorber valve system.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The method for predicting the fatigue life of the shock absorber valve system provided by the present invention applies fluid mechanics and finite element analysis methods to establish a parametric model for the fatigue life of the shock absorber valve system, inputs the relevant parameters affecting the damping force as the characteristic variables of the model, and can obtain the analysis models of different shock absorber valve system combinations by adjusting the characteristic variables;

[0025] 2. The method for predicting the fatigue life of the shock absorber valve system provided by the present invention quickly verifies the effectiveness of the model by simulating and analyzing the indicator diagram and damping force of the shock absorber, and timely reviews the parameters and makes optimizations.

[0026] 3. The method for predicting the fatigue life of the shock absorber valve system provided by the present invention takes the preload-open valve-closed valve stress as a cycle period, and regards the stress change of the shock absorber valve system as a single stress cycle of the fatigue analysis stress, making the analysis more in line with the actual situation.

[0027] 4. The shock absorber valve train fatigue life prediction method proposed by the present invention can quickly and efficiently analyze the fatigue life of the shock absorber valve train combination, and through a large number of actual measurements and comparisons, it can be concluded that the simulation and test error accuracy can be controlled within 10%. Description of the Drawings

[0028] By reading the detailed description of the non-restrictive embodiments with reference to the following drawings, other features, objectives, and advantages of the present invention will become more obvious:

[0029] Figure 1 It is a flowchart of a shock absorber valve train fatigue life prediction method described in the first embodiment;

[0030] Figure 2 It is a schematic diagram of a parametric model of a shock absorber valve train fatigue life prediction model described in the first embodiment;

[0031] Figure 3 It is a shock absorber indicator diagram obtained by simulation in the first embodiment;

[0032] Figure 4 It is a schematic diagram of a shock absorber valve train virtual simulation model and loading method described in the first embodiment;

[0033] Figure 5 It is a schematic diagram of the preload-opening valve-closing valve state of the shock absorber valve train described in the first embodiment. Detailed implementation manners

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Usually, the components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the present application that is claimed, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0036] As Figures 1 to 5 shown, this embodiment provides a shock absorber valve train fatigue life prediction method. By establishing a parametric model of the shock absorber valve train fatigue life through fluid mechanics and finite element analysis, and comparing the simulated damping force with the measured damping force, the effectiveness of the model can be quickly verified. Applying this parametric model and the valve train fatigue analysis method, the fatigue life of the shock absorber valve train combination can be quickly and efficiently analyzed.

[0037] Figure 1 The following is a flowchart of a method for predicting the fatigue life of a shock absorber valve system provided in this embodiment, which specifically includes the following steps:

[0038] Step 1. Establish a parametric model for predicting the fatigue life of the shock absorber valve system as shown in Figure 2 Figure.

[0039] Step 1.1 Before establishing the parametric model for predicting the fatigue life of the shock absorber valve system, determine the basic parameters involved in the model. These parameters mainly include the physical and mechanical characteristics during the operation of the shock absorber, which will be used for subsequent fluid mechanics and mechanics calculations. As shown in Figure 2 Figure, the main parameters include A - oil and gas (such as the viscosity, fluidity of the oil and the compressibility of the gas); B - excitation signal (external load or vibration signal, etc.); C - friction force signal (the influence of the friction force on the working state of the valve plate); D - oil storage cylinder; E - flow valve; F - rebound valve; G - compression valve; H - compensation valve; I - working cylinder, etc. By applying these parameters, the analysis models of different shock absorber valve system combinations can be obtained by adjusting the characteristic variables.

[0040] Step 1.2 Based on the above parameters, apply the damping force calculation formula to calculate the pressure difference when the oil flows through each valve plate, and obtain the variation law of the damping force.

[0041] The damping force of the parametric model for the fatigue life of the shock absorber valve system is an important index for evaluating the external characteristics and the effectiveness of the model. According to fluid mechanics, the main reason for the generation of the damping force is that the oil flowing through the throttle valve system during the operation of the shock absorber generates a corresponding pressure difference. Its calculation formula is:

[0042]

[0043] In the formula: F(t) is the damping force, is the pressure difference between the upper and lower chambers of the working cylinder, is the pressure difference between the lower chamber of the working cylinder and the oil storage chamber, is the pressure of the oil storage chamber, is the leakage pressure, is the external atmospheric pressure, is the piston cross-sectional area, is the connecting rod cross-sectional area, is the leakage area, F f is the friction force.

[0044] Step 1.3 Use the aforementioned parameters and the fluid mechanics calculation results to establish as shown in Figure 2The parametric model for predicting the fatigue life of the shock absorber valve system, whose parameters include A - oil and gas; B - excitation signal (establish a dynamic response model of the shock absorber under different working conditions according to the characteristics of the external excitation signal, including the amplitude, frequency, etc. of vibration); C - friction force signal; D - oil storage cylinder; E - flow valve; F - rebound valve; G - compression valve; H - compensation valve; I - working cylinder, etc., integrates each component and working principle of the shock absorber. Among them, the parametric model for predicting the fatigue life of the shock absorber valve system mainly includes:

[0045] (1) Model of valve plate and valve seat: In the valve plate model, for each valve plate, a finite element model (FEM) is used for structural analysis to determine its deformation and stress under different pressures and friction forces. As Figure 4 and Figure 5 shown, in the model, the valve plate is divided by solid elements, the basic size of the valve plate grid is 0.2 mm, there are at least three layers in the thickness direction, and the middle hole of the valve plate is fully constrained.

[0046] (2) Oil flow model: The flow and flow rate of oil are the key factors affecting the damping force, and the hydrodynamic equation is needed to simulate the flow of oil between each valve plate, considering flow resistance, turbulence effect, etc.

[0047] (3) Excitation model: Establish a dynamic response model of the shock absorber under different working conditions according to the characteristics of the external excitation signal, including the amplitude, frequency, etc. of vibration.

[0048] Step 2: Simulate and analyze whether the indicator diagram of the shock absorber in the model is full and without distortion. As Figure 3 shown, if the simulated indicator diagram is smooth and full, it means that the model has the function of the shock absorber and operates reasonably, and the next step can be carried out; if the indicator diagram is not full and there is distortion, it means that there is a problem with the model, and it is necessary to return to find the reason and debug the parameters.

[0049] Step 3: Simulate and analyze the damping force of the shock absorber and compare it with the measured damping force to see if the error is less than 10%. As shown in Table 1 below, it can be found from the comparison results of the simulation analysis results and the measured results: the errors of the simulation results of the damping characteristics of the shock absorber at multiple speed points are all less than 10%, meeting the requirements of engineering analysis. Among them, the maximum error is 1.44% and the minimum error is 0, proving that the model is true and effective.

[0050]

[0051] Table 1 Comparison table of simulation analysis results and measured results

[0052] Step 4: Extract the preload-opening valve-closing valve of the shock absorber valve system as a cyclic stress characteristic. To analyze the fatigue life of the shock absorber valve system, it is necessary to further convert the damping force into stress analysis. Considering the stress cycle characteristics that the shock absorber may experience during actual use, analyze the stress changes of the shock absorber during the preload, opening valve, and closing valve processes. By applying a forced displacement load, obtain the stress in the initial installation state, and then apply a uniform load to the valve system according to the fluid action area to analyze the stress changes during the opening valve and closing valve processes. First, analyze the process of the shock absorber under preload, and obtain the stress of the shock absorber valve system in the initial installation state (preload) through the forced displacement load; secondly, perform a uniform load on the shock absorber valve system according to the fluid action area for opening valve analysis, and analyze the stress change law during the opening valve process of the shock absorber; furthermore, perform a uniform load on the shock absorber according to the fluid action area for closing valve analysis, and analyze the stress change law during the closing valve process of the shock absorber. Finally, take the preload-opening valve-closing valve stress as a cycle period, and regard the stress change of the shock absorber valve system as a single stress cycle for fatigue analysis stress. Extract the stress data of the three stages of preload, opening valve, and closing valve, and combine them into a complete cyclic stress characteristic. These stress cycle characteristics will be used as the input for fatigue analysis. The entire force-bearing cycle of the shock absorber valve system includes three states: preload-opening valve-closing valve. Taking the preload-opening valve-closing valve stress as a cycle period and regarding the stress change of the shock absorber valve system as a single stress cycle for fatigue analysis stress makes the analysis more in line with the actual situation.

[0053] Step 5: Use FEMFAT software to calculate the fatigue life of the valve system. Import the above-mentioned preload-opening valve-closing valve stress cycle into FEMFAT software, and use the fatigue data of the material (such as the S-N curve) to predict the life, and quickly and efficiently analyze the fatigue life of the shock absorber valve system combination. At the initial stage of model establishment, the fatigue life of the simulation analysis can be compared with the measured bench fatigue, and based on the comparison results, the simulation grid, different valve plate loading areas, valve plate contact forms, etc. can be optimized. After model iteration optimization and experience accumulation, it is concluded that the final simulation and test error accuracy can be controlled within 10%.

[0054] The specific embodiments of the present invention have been described above. Through the above description, relevant staff can make various changes and modifications completely within the scope of not deviating from the technical idea of the present invention.

Claims

1. A method for predicting the fatigue life of a shock absorber valve system, characterized in that, It includes the following steps: Step 1: Apply hydrodynamic and finite element analysis methods to establish a parametric model for predicting the fatigue life of the shock absorber valve system. Input the parameters affecting the damping force as the characteristic variables of the model. The parameters include A - oil and gas; B - excitation signal; C - friction force signal; D - oil storage cylinder; E - flow valve; F - rebound valve; G - compression valve; H - compensation valve; I - working cylinder. By adjusting the characteristic variables input into the model, an analysis model for different shock absorber valve system combinations can be obtained; Step 2: Simulate and analyze whether the indicator diagram of the shock absorber in the parametric model for predicting the fatigue life of the shock absorber valve system is full and without distortion. If the simulated indicator diagram is smooth and full, it indicates that the model has the function of the shock absorber and the next step can be carried out; If the indicator diagram is not full and there is distortion, it is necessary to return to find the reason and debug the parameters; Step 3: Simulate and analyze whether the error between the damping force of the shock absorber in the parametric model for predicting the fatigue life of the shock absorber valve system and the measured damping force is less than 10%. If the error is less than 10%, it proves that the model is true and effective and the next step can be carried out. Otherwise, the parameters of the model need to be further optimized; Step 4: Extract the stress characteristics of one cycle of preload - valve opening - valve closing of the shock absorber valve system; Step 5: Import the stress cycle of preload - valve opening - valve closing of the shock absorber valve system in Step 4 into the FEMFAT software to analyze the fatigue life of the shock absorber valve system combination.

2. The method for predicting the fatigue life of a shock absorber valve system according to claim 1, wherein In Step 2 and Step 3, the damping force of the shock absorber is calculated by the following formula: Where: F(t) is the damping force, is the pressure difference between the upper and lower chambers of the working cylinder, is the pressure difference between the lower chamber of the working cylinder and the oil storage chamber, is the pressure of the oil storage chamber, is the leakage pressure, is the external atmospheric pressure, is the piston cross-sectional area, is the connecting rod cross-sectional area, is the leakage area, F f is the frictional force.

3. The fatigue life prediction method of the shock absorber valve system according to claim 1, characterized in that Step 4 includes the following specific steps: First, analyze the process of the shock absorber under preload, and obtain the stress of the initial installation state of the shock absorber valve system through forced displacement load. Secondly, conduct a uniform loading on the shock absorber valve system according to the fluid action area for valve opening analysis, and analyze the stress change law during the valve opening process of the shock absorber. Furthermore, conduct a uniform loading on the shock absorber according to the fluid action area for valve closing analysis, and analyze the stress change law during the valve closing process of the shock absorber. Finally, take the preload - valve opening - valve closing stress as a cycle period, and take the stress change of the shock absorber valve system as a single stress cycle for fatigue analysis.

4. The method for predicting the fatigue life of a shock absorber valve system according to claim 1, characterized in that In the parametric model for predicting the fatigue life of the shock absorber valve system, the valve plate is divided by solid elements. The basic size of the valve plate grid is 0.2 mm, and there are at least three layers in the thickness direction. The middle hole of the valve plate is fully constrained.

5. The method for predicting the fatigue life of the shock absorber valve system according to claim 1, characterized in that Step 5 also includes the following steps: Compare the fatigue life calculated by simulation in Step 5 with the measured fatigue to optimize the parametric model for predicting the fatigue life of the shock absorber valve system.

6. The method for predicting the fatigue life of the shock absorber valve system according to claim 5, wherein The optimization of the parametric model for predicting the fatigue life of the shock absorber valve system includes adjusting and optimizing the simulation grid, different valve plate loading areas, and valve plate contact forms.

7. A shock absorber valve system fatigue life prediction system, characterized in that It is used to implement the method for predicting the fatigue life of the shock absorber valve system according to any one of claims 1 to 6.

Images